Road Surface Technology 2025

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Q4 2025 ISSUE 11

TECHNOLOGY A N A LY S I N G

T H E

L AT E S T

T E C H N O L O G Y,

P R O D U C T S

&

S E R V I C E S

BASF’S ASPHALT MODIFICATION WITH BUTONAL MB 5126 p4

p22 Benninghoven MULTI JET burner in Norway

p46 Dynapac’s Seismic Asphalt compaction system

p49 FAE’s RPL/EX-45 road planer in Finland

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11 Q4 2025 ISSUE

Y G O L O N H C E T G A N A LY S I N

T H E

L AT E S T

T E C H N O L

O G Y,

P R O D U C T

S

&

S E R V I C E S

ustainability, the circular economy and carbon footprints continue to dominate the pages of Road Surface Technology Review. From binder modification and asphalt compaction to asphalt removal and surface inspections, the goal is to take the guess-work out of creating the perfect road surface.

To this end, compaction is becoming more and more an exact PHALTAsphalt system from Dynapac. It ASSeismic ’S the SFby science, as BA noted H ION WITasphalt-compaction AT IC IF OD M automatically detects the optimum frequency and p4 26 51 B M L NA TO it accordingly. The sophisticated incorporation of BUadjusts continuously temperature sensors and frequency adjustment of the vibrating rollers to get a long-lasting surface will pay dividends in the far-off future for many road agencies and local authorities.

Sophistication is also the key word when it comes to describing Xenomatix’s 6D road-scanning system and FAE’s RPL/EX- 45 road planer. The complex but compact RPL/EX45 planer can p49 get into hardp46 planer in Finland FAE’s RPL/EX-45 road p22 compaction system ac’s Seismic Asphalt Dynap to-reach places nghov foren asphalt removal.

Meanwhile, Xenomatix’s scanning ay Norw in r MULTI JET burne Benni system will give insights into how new sensors and artificial intelligence tools generate even more valuable data for pavement management. It should never be forgotten that the perfect road surface will likely begin

S

CONTENTS 4

ASPHALT MODIFICATION

BASF’S Butonal MB 5126 additive

12 MAINTENANCE PLANNING

ARRB and the financial perspective

16 WARM-MIX ASPHALT WMA and net-zero projects

26 ASPHALT PRODUCTION

John Read and capacity production

29 WORKFLOW MODELLING

at the asphalt-mixing plant – which could run on hydrogen, according to Benninghoven. At the plant is where bitumen quality and additives can be adjusted to suit a road’s physical environment. Products from BASF, Fibenol, Iterchimica and Sripath are highlighted.

Creating the perfect asphalt mix is one thing. Delivering it to site in still perfect condition is something else. Consider the push-off technology from Fliegl. It also is important where that journey to the site begins, according to a report from Nynas.

Finally, we share a sobering report from John Read - a respected voice in the asphalt industry. He envisages a decline in production capacity for bitumen at the same time as global demand rises. To what degree do problems lie ahead?

We, here at Route One Publishing, hope you find this year’s Road Surface Technology Review informative and useful. Please tell your colleagues about the publication and the upcoming digital version – as well as back issues – of the RST Review. ■

David Arminas, EDITOR darminas@ropl.com

37 INTERVIEW

Nynas reports

34 CASE STUDY

Banking on a SmoothRide

22 ASPHALT PLANT

David Arminas

DESIGNERS:

Simon Ward, Andy Taylder Sarah Biswell

DATA & MARKETING MANAGER:

Italy:

OFFICE MANAGER:

MANAGING DIRECTOR:

Andrew Barriball CEO:

Roger Adshead

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Fulvio Bonfiglietti Tel: +39 339 1010833 Email: fulvio.bonfiglietti@gmail.com Asia / Australasia:

Roger Adshead Tel: +44 7768 178163 Email: radshead@ropl.com

56 ROAD SCANNING Sensors and 6D inspections

Dynapac’s Seismic Asphalt system

ADVERTISEMENT SALES: Sales Director

PRODUCTION MANAGER:

Kelly Thompson

Fliegl’s push-off technology

46 COMPACTION

WEB MANAGER:

Alan Cansick

54 MATERIAL DELIVERY

Sripath’s carbon reduction

SUB-EDITOR:

Nick Bond

Precision in the age of ADAS

43 POLYMERIC ADDITIVES

Graeme McQueen Tel: +44 7833 445592 Email: gmcqueen@ropl.com

EKH Services

50 ROAD MARKINGS

Lignin as a partial substitute

Benninghoven’s hydrogen burner

EDITOR:

FAE technology in Finland

40 ASPHALT COMPONENTS

Trimble’s 3D approach

32 MATERIAL SOURCING

49 ASPHALT REMOVAL

Topcon Positioning Systems

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ADDRESS:

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GLOBAL OUTLOOK. ROAD SURFACE TECHNOLOGY (PRINT)

Route One Publishing Limited, Second floor, West Hill House, West Hill, Dartford, Kent DA1 2EU, UK Tel: +44 1322 612055 Fax: +44 1322 788063 Email: [initialsurname]@ropl.com (eg: radshead@ropl.com)

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ROAD SURFACE TECHNOLOGY 2025

03

FLEXIBLE ASPHALT

ASPHALT MODIFICATION WITH BUTONAL MB 5126 The Butonal MB 5126 additive from BASF allows the polymer content to be

flexibly adjusted depending on the traffic load - for example, for heavily used intersections or bus lanes - without the need for different special bitumens.

Daniel Gogolin, Mario Šandor and Thomas Falvo explain. he demands placed on modern road surfaces are constantly increasing. In addition to high load-bearing capacity and durability, environmental aspects and energy efficiency are increasingly coming into focus.

Against this backdrop, Butonal MB 5126 additive - a water-based (aqueous) polymer dispersion that allows the asphalt mix to be modified directly in the mixing plant - was used for the first time in Germany. It was part of a pilot project in Dortmund where the aim was to improve performance of the asphalt while reducing processing temperatures.

Butonal MB 5126 creates a foam structure

T

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ROAD SURFACE TECHNOLOGY 2025

when mixed into the asphalt mixer. It leads to the formation of a polymer network in the binder, and thus to a polymer-modified asphalt. The technology allows the polymer content to be flexibly adjusted depending on the traffic load - for example, for heavily used intersections or bus lanes - without the need for different special bitumens.

PILOT PROJECT ON BORNSTREET Bornstreet, a main road in Dortmund, was selected via a data-based infrastructure management system. The decision was based on condition data (ZTV-ZEB), substance analyses (pavement scanner, georadar)

and operational experience. The measure comprised the renewal of the entire bound superstructure due to severe substance loss.

Three variants of stone mastic asphalt (SMA 8 S) with temperature-reduced asphalt (TA) were tendered and installed for the asphalt-surface course: - Variant 1 (reference): SMA 8 S with PmB 25/55-55 A, at a temperature of ~180°C. - Variant 2: SMA 8 S with 6% Butonal MB 5126 (3% polymer), at a temperature of ~145°C. - Variant 3: SMA 8 S with 9% Butonal MB 5126 (4.5% polymer), at a temperature of ~145°C.

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FLEXIBLE ASPHALT

SMA 8 S 25/55-55 A (Reference)

SMA 8 S 50/70 + 9 % Butonal 5126 (4,5 % Polymer)

SMA 8 S 50/70 + 6 % Butonal 5126 (3 % Polymer)

Photo 1: Implemented variants of the asphalt-surface layer

Photo 2: Recording of compaction performance using radiometric measurements by PTM

Photo 3: Sampling of asphalt mix for control tests and performance investigations by PTM

Photo 4: Core sampling for control tests by PTM (here: variant I)

The modification was carried out lane by lane: the high-traffic bus lanes were given variant 3, the other lanes variant 2. A smaller area was equipped with the reference variant.

PAVING AND COMPACTION Paving took place on April 30, 2024, at air temperatures of 19°C (variant 3) and 23°C (variant 2). The mix temperatures were between 152°C and 158 °C, the paving temperatures between 146°C and 152°C. Despite the lower temperatures, the material proved to be very compactable.

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ROAD SURFACE TECHNOLOGY 2025

Radiometric measurements showed - Variant 3: degree of compaction 100.7%, void content 1.6% by volume - Variant 2: degree of compaction 100.3%, void content 1.9% by volume - Reference: degree of compaction 99.5%, void content 3.2% by volume CONTROL TESTS On May 8, 2024, drill cores were taken and tested in accordance with ZTV Asphalt-StB 07/13. The results confirmed the measurements taken during construction:

- Variant 3: degree of compaction 100.4%, void content 2% by volume, layer bond 24.5kN - Variant 2: degree of compaction 101%, void content 1.6% by volume, layer bond 24.9kN - Reference: degree of compaction 99.2%, void content 3.9% by volume, composite layer 10.5kN PERFORMANCE TESTS - Stiffness behaviour The stiffness was determined using multistage tests at different temperatures and a test www.globalhighways.com

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FLEXIBLE ASPHALT

Stiffness moduli for test frequency f = Hz [MPa]

Average stiffness moduli for test frequency f = 10Hz

frequency of 10Hz. Results showed higher stiffness at medium temperatures (0-20°C) with Butonal MB 5126 and lower stiffness at low temperatures (< 0°C) compared to the reference.

- Cooling properties (TSRST) The cooling tests resulted in fractional temperatures < -20°C for all variants. Variant 2: -3.3°C, variant 3: -2.8°C. Breaking stresses were between 4.1MPa and 4.5MPa. - Tensile threshold tests (UCTST) The elongation at break was significantly higher in the modified variants: reference: 6.7 ‰, variant 2: 12.4 ‰, variant 3: 13.9 ‰.

The failure load cycles were comparable, and the fatigue resistance of all variants was considered sufficient.

THE FUTURE The tests show that temperature-reduced asphalt mixes with Butonal MB 5126 meet the requirements for paving and compaction. But they also perform better than conventional mixes in terms of deformation resistance, low-temperature behaviour, fatigue and stiffness behaviour. The technology offers a sustainable and adaptable solution for municipal road construction and enables a flexible response to different load scenarios.

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ROAD SURFACE TECHNOLOGY 2025

20.000 15.000 10.000 5.000

20 oC

10 oC

0 oC

-10 oC

SMA 8 S - PmB 25/55-55 A

7.548

11.114

16.918

21.316

SMA 8 S - 50/70 + 6,0 M.-% Butonal 5126

8.234

13.337

16.857

21.001

SMA 8 S - 50/70 + 9,0 M.-% Butonal 5126

9.924

15.154

18.225

19.612

Figure 1: Average stiffness moduli as a function of test temperature at f = 10Hz

Deformation behavior under heat in a uniaxial pressure threshold test Stress cycle

Expansion rate

11.000

80,0

10.000

70,0 8.622

8.000 7.000

10.000

68,4

9.000

7.797 51,8

7.130

50,0

34,6

40,0

6.000 5.000 4.000

24,2

3.000 2.000 1.000 0

60,0

30,0 20,0

2.487

17,1 1.595

15,4

10,0 0,0

SMA 8 S PmB 25/55-55 A T=60oC SMA 8 S PmB 25/55-55 A T=50oC

Expansion rate [e* in %0X10-4/n]

- Deformation behaviour under heat Uniaxial compression-set tests at 50°C and 60°C showed significant improvement in deformation resistance with Butonal MB 5126. Variant 3 was the only one to meet the requirement of 10,000 load cycles.

25.000

Test temperature

Stress cycle [n]

- Trace formation The rutting was tested up to 100,000 rollovers. Variant 3 showed the lowest rut depth (3.9mm), while the reference showed the highest rut depth (4.7mm). A slight improvement in deformation properties was observed with Butonal 5126.

30.000

SMA 8 S SMA 8 S 50/70+6,0 M.-% 50/70+9,0 M.-% Butonal 5126 Butonal 5126 T=60oC T=60oC SMA 8 S SMA 8 S 50/70+6,0 M.-% 50/70+9,0 M.-% Butonal 5126 Butonal 5126 T=50oC T=50oC

Figure 2: Test results on the deformation behaviour under heat of all tested variants

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FLEXIBLE ASPHALT

7,000 6,000 4,496

BASF https://products.basf.com/global/en/ cp/n-butanol

5,000 4,000 3,000 2,000

Cryogenic fracture temperature [oC]

The results of the pilot project in Dortmund underline the potential of Butonal MB 5126 for a broader application in road construction - both in a municipal and supra-regional context. The possibility of direct modification in the mixing plant, the reduction in processing temperatures and the improved performance make the additive a promising component of future asphalt strategies. ■

4,281

4,147

1,000 0,000

0,0 -4,0 -8,0

Cryogenic tensile strength [MPa]

Cold properties in cooling test TSRST

-12,0 -16,0 -20,0 -24,0

-25.4 -28.7

-28.2

SMA 8 S 50/70 + 6.0 M.-% Butonal 5126

SMA 8 S 50/70 + 9.0 M.-% Butonal 5126

-28,0 -32,0 -36,0 SMA 8 S - Reference PmB 25/55-55 A

Figure 3: Test results on cold behaviour - cooling tests

Daniel Gogolin has been managing director of the engineering group PTM Dortmund since 2014. PTM specialises in testing and researching various materials, particularly asphalt, bitumen and additives, for public and private clients. He is also head of PTM’s asphalt-testing laboratory. In 2006 he completed his civil engineering studies at Ruhr University Bochum and stayed on as a research assistant in the field of transportation infrastructure until 2011.

Gogolin is a board member of the Federal Association of Independent Institutes for Structural Engineering Testing and a lecturer in road-construction technology at Ruhr West University of Applied Sciences.

Mario Šandor joined BASF in 1998 and is now head of business management for asphalt performance for EMEA. He holds a doctorate from the Technical University of Munich and then continued with postdoctoral work at Lehigh University in the US. Šandor supports various associations through his memberships, including the European Asphalt Association (EAPA), the German Asphalt Association (DAV) and is a board member of Eurobitume.

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ROAD SURFACE TECHNOLOGY 2025

Test parameters

Variant 1

Variant 2

Variant 3

Reference

SMA 8 S

SMA 8 S

SMA 8 S PmB 25/55-55 A

50/70 6% Butonal MB 5126

50/70 9% Butonal MB 5126

Breaking strain

‰

6.7

12.4

13.9

Fracture load cycle number

-

257543

248856

272595

Table 1: Arithmetically averaged test results for uniaxial tensile stress-strain tests according to TP Asphalt-StB, Part 46B

Thomas Falvo studied economics at the University of Cologne. After serving as managing director of the family roadconstruction company, he moved to the asphalt-additive manufacturer Star Asphalt in 1999, where he also served as managing director until 2014. During this period, he strengthened the company’s cooperation with Calabria University, publishing several papers, mainly related to bitumen rheology. After 10 more years at Ingevity as business development manager for EMEA, he joined BASF in 2024 as senior technical marketing manager for asphalt performance for EMEA. www.globalhighways.com

produzionepropria.com illustrazione benedetta fasson 2024

COLOURED ASPHALTS, CYCLE PATHS

-18° REDUCTION OF THE TEMPERATURE OF THE PAVEMENT BY UP TO 18°C

INCREASED VISIBILITY AND ROAD SAFETY

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road surface september 2025.indd 3

24/09/25 18:00

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ROAD INSPECTIONS

FULL-SPECTRUM ROADCONDITION EVALUATION

Credible road-condition data is increasingly critical for addressing road safety. To this end, full-spectrum measurement supports decision-making in relation to the International Road Assessment Program (iRAP). Simon Tetley, of ARRB Systems South Africa, explains. aving a complete dataset, incorporating both surface and structural data (collected simultaneously), enables road asset managers to better understand the true condition of their network. The ultimate goal is to ensure that the data collected is verified and validated.

Credible road-condition data is increasingly critical for addressing road safety. The International Road Assessment Programme (iRAP), endorsed by the United Nations, has a certification process for equipment to record road features that impact road safety. The data is used to undertake a network-level assessment and determine ‘Star Ratings’ based on the existing attributes of a road.

This paper will show how comprehensive, full-spectrum measurement supports decision-making in relation to the iRAP. Comprehensive road-condition measurements can also rationalise data management - crucial for optimising roadmaintenance budgets and reducing traffic fatalities.

H

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ROAD SURFACE TECHNOLOGY 2025

IDENTIFICATION Roads are generally designed and built based on strength characteristics or bearing capacity. Yet, they are managed generally according to their functional condition because strength has historically been difficult and expensive to routinely measure.

Until now, overall pavement condition has been largely determined using the International Roughness Index. This IRI assumes that if a road has a smooth riding quality, the pavement is performing as intended. However, experience shows that the opposite can also be true.

Road agencies around the world are routinely collecting pavement-stiffness properties, at traffic speed, along with associated synchronised and simultaneously collected surface-condition and functional data. Combining pavement structural and surface data, enables the correct identification and cause of pavementdistress mechanisms.

The capability of continuous highaccuracy and high-resolution data enables infrastructure managers to pinpoint areas

where pavement structure is suspect and potentially subject to failure.

Agencies have started to report projects where their comprehensive data helps to avoid large overspending. But what can be obtained from using comprehensive measurements where structural- and functional-condition data are combined? The following examples show how these combined and simultaneous measurements can be used.

For the purposes of this discussion, cases will be categorised as follows: • Case 1) A section of pavement appears deficient from the surface AND is also determined to be structurally deficient; • Case 2) A section of pavement appears acceptable from the surface BUT is determined to be structurally deficient; • Case 3) A section of pavement appears deficient from the surface BUT is determined to be structurally adequate; • Case 4) A section of pavement appears acceptable from the surface AND an agency is able to confirm it is also structurally adequate. www.globalhighways.com

ROAD INSPECTIONS

CASE 1 The common belief is that structural distresses will manifest themselves, eventually, in surface deterioration. While this may typically be true, it is not always the case and, therefore, structural assessments should be conducted to confirm the presence of structural deterioration before rehabilitation treatments are planned. It is common for some agencies to delay treatments on roads when such extensive work is required. However, the need for confirmation is an essential part of appropriate treatment selection.

Being able to locate pavement sections in the road network where both pavement surface and structural capacity are challenged allows the agencies to undertake far better informed decisions when prioritising financial resources for maintenance.

On roads where the surface is heavily deteriorated and the structural capacity is low:

CASE 2 Continuous structural-capacity assessment can reveal isolated or discrete sections of a road network that appear acceptable from the surface. Yet, for a number of reasons, these sections cannot provide the same structural support as adjacent sections of road pavement.

On road sections where the functional conditions are acceptable but the structural condition is not, isolated recurring maintenance issues will create frustration for years to come. As well, larger areas of structurally deficient pavement will ultimately lead to changes in treatment forecasts. This can prove very costly and ultimately lead to pavement surfaces that do not provide acceptable levels of service for road users.

As an example, improperly constructed pavements can experience early structural

problems that may not be as obvious from the surface (see figure 1).

If agencies detect structural issues early: a.) They can conduct spot repairs in advance of surfacing treatments. This can improve treatment performance and identify optimal asphalt- or concreteoverlay thicknesses; b.) They can alter treatment forecasts and strategies to mitigate more extensive areas of structural concern that are not visible from the surface.

For some pavement types, such as composite, it is helpful to be aware of underlying conditions to properly identify and plan treatment needs.

© Marc Bruxelle | Dreamstime.com

a.) The surface will continue to decline and could ultimately cause an acceleration of the deterioration of the structural capacity (allowing water infiltration) and complete the structural failure. b.) If the agency plans an extensive treatment based on surface deterioration alone, the investment of the resurfacing could result in unnecessary expenditure because a lack of structural capacity will cause rapid deterioration of a newly laid surface. c.) If the agency delays treatment as a result of perceived deterioration, the cost for repair and maintenance will increase significantly - a cost that might not have been foreseen.

FIGURE 1: Structural issues - if detected early - can indicate future problems

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ROAD SURFACE TECHNOLOGY 2025

13

© Janks ,| Dreamstime.com

ROAD INSPECTIONS

CASE 3 Observations have also been made of sections of pavement that exhibit extensive surface deterioration, leading one to believe extensive structural repairs are required.

Without the corresponding structural assessment: a.) An agency may elect to delay treatment because of the perceived deterioration.

The surface may continue to decline and could ultimately cause structural deterioration by allowing water infiltration. This will likely lead to accelerated deterioration, regardless of whether or not structural issues existed; b.) If the agency plans an extensive treatment based on the surface deterioration, unnecessary expenditure could result.

CASE 4 When the surface is heavily deteriorated and further assessment reveals no structural deterioration: a.) An agency can remove and replace the problem surface layer and avoid more extensive unnecessary costly repair due to delayed intervention; b.) An agency can use saved financial resources to investigate true cause(s) of surface anomalies.

b.) If the agency plans treatment based on performance prediction, this could result in unnecessary expenditure.

When structural assessments can be readily conducted: a.) An agency can more confidently project performance expectations and more accurately plan for future needs; b.) An agency can use saved resources to address projects of greater need.

Regardless of which scenario applies, analysis of continuous data provides a more detailed assessment within a project. Rather than assigning some ‘average’ condition for treatment selection and design, discrete sections can be identified with greater confidence and accuracy. In this way, areas of greater need will get treated.

These project-level decisions can now be made with network-level data. Such work can be performed in advance of larger rehabilitation projects to produce a more ‘homogeneous’ structure for more cost-

effective designs. Potentially, isolated repairs of this nature may even be performed on their own to ‘buy some time’ before additional work is needed.

Without implementing correctly designed remedial interventions and providing a robust and safe road infrastructure, the annual number of road deaths worldwide is projected to increase to some 2.4 million by 2030, the majority of these deaths occuring in low- and middle-income countries¹. Almost half of those killed will be vulnerable road users - motorcyclists, bicyclists, pedestrians. The International Road Assessment Programme (iRAP) was created specifically to create safer roads². iRAP assessments are carried out across the globe in numerous countries that are all aligned with the iRAP vision of “a world free of high-risk roads”.

A key point in the iRAP is accurate and detailed data for the road network. The fastest way of collecting such data is using iRAP-accredited equipment. These include network-survey vehicles for gathering comprehensive measurements.

FIGURE 2: Images as viewed on the Hawkeye Toolkit

When sections of pavement appear to have limited surface deterioration, it is beneficial to confirm that these sections truly require no work for the foreseeable future.

Without the corresponding structural assessment: a.) An agency might programme work based solely on the pavement’s age or unsupported performance expectations. But this will likely lead to misappropriation of funds, regardless of whether structural issues existed or not;

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ROAD SURFACE TECHNOLOGY 2025

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ROAD INSPECTIONS

Road inspection and supporting data

Road survey

ViDA - online software

Star Rating Scores (SRS)

Star Ratings

Countermeasure generation

Road coding

Supporting data

Detailed condition report

Estimate of deaths and serious injuries prevented

Implementation

Safer Roads Investment Plans

Detailed planning

Star Rating designs

Post-construction Star Ratings

Economic assessment

FIGURE 3: All of the above processes can be undertaken only once comprehensive data is received using specialised equipment such as the iPAVe.

RAP ASSESSMENTS The iRAP assessment method is qualitative in nature so to produce safety ratings and investment plans, accurate and detailed data of the road network is required. Road surveys are the fundamental part of the iRAP process and are undertaken to collect digital images of the road using multi-view high-resolution cameras as well as capturing geo-referencing data that allows for precise co-ordinates and centreline distances to be assigned to each image.

The fastest way of collecting such images is with iRAP-accredited equipment. The pavement-assessment vehicle iPAVe is not only iRAP accredited, but, given its fullspectrum data-collection capability, is an enhanced road-condition data-collection device.

After completing a road survey, the collected images are assessed by trained and accredited analysts to record road attributes at 100m intervals. The system adopted to undertake the coding assessment is the Hawkeye Toolkit (see figure 2).

Images can be viewed at various intervals such as 5m, 10m and 20m, while providing road-attribute data, including grade, co-ordinates and lane widths. The Hawkeye Toolkit ensures that results are accurate and consistent for every individual 100m-assessment segment. www.globalhighways.com

Once the coding is completed, the data undergoes quality assurance. Then the processed data is uploaded onto ViDA³, which is iRAP’s free-to-air online platform.

ViDA is a portal that generates Star Ratings and Safer Roads Investment Plans based upon the road attributes that have been coded.

The Safer Roads Investment Plan is used to plan maintenance and safety-improvement activities for the road network. It also helps understand the cost of countermeasures.

ViDA allows for Star Ratings before and after implementation of countermeasures. This gives the analyst a good indication of which countermeasures are more beneficial for a given road environment.

The journey from road survey to development of a Safer Roads Investment Plan is summarised in figure 3.

OPTIMISING COST One of the major concerns when performing pavement-condition surveys is the cost compared to the value added. Using survey vehicles for road-data collection has been the norm for some time, although many countries still rely on manual or ‘windscreen’ pavement-condition surveying.

Either way, functional and structural properties have typically been collected separately.

Introducing comprehensive condition surveys, where all pavement-condition parameters are collected in an integrated, simultaneous manner, naturally raises the financial question. A study by this author, presented at the 18th IRF World Meeting and Exhibition in Dubai in 2021, showed that there is a cost saving when using a falling weight deflectometer and network service vehicle in combination³. Using automated condition surveys not only provides better and more reliable data, but also provides a noticeable cost saving for the agencies³. ■ Simon Tetley is chief technical officer for pavement engineering at ARRB Systems, a global provider of road asset and pavement management solutions. He is based in Cape Town, South Africa. www.arrbsystems.com simon.tetley@arrbsystems.com References: ¹International Road Assessment Program, IRAP https://irap.org. ²The iRAP online software: http://vida.irap. org/en-gb/home. ³Tetley, S. A study into the benefit and cost effectiveness of using state-of-the art technology for road network level condition assessment; 18th IRF World Meeting & Exhibition, November 7 -10, 2021.

ROAD SURFACE TECHNOLOGY 2025

15

WMA ADDITIVES

THE NET-ZERO CASE FOR WMA ADDITIVES

Warm mix asphalt (WMA) chemical additives can be a multi-functional solution for ‘net zero’ asphalt pavement. Shahin Eskandarsefat and Loretta Venturini, from Iterchimica, consider how and when they can be used.

hen introduced for the first time, warm mix asphalt (WMA) chemical additives were used mainly for reducing asphalt material paving temperatures without compromising original performance properties. The additives were used first in Europe in the mid-1990s and then introduced into the US around 2002. In comparison to organic additives, such as waxes and fatty amides, as well as plant-production foaming techniques and foaming additives (hydrophilic minerals), WMA chemical additives change neither binder nor final asphalt original performance and properties.

But this is not the only reason for the evergrowing use of chemical additives in asphalt production, as shown in NAPA’s Asphalt Pavement Industry Survey in 2021¹. The advantages of using chemical WMA additives can be divided into two technical groups: those associated with reduced temperature;

W

those typically linked to the workability of the mixture, which can be achieved even if the production temperature is not reduced.

CHEMICAL ORIGINS The chemical composition of warm mix asphalt/workability aid additives can vary significantly, depending on their intended function and mechanism of action. To date, a range of chemical bases has been introduced for use in asphalt production. These include amine-based, phosphoric acid-based, vegetable (bio-based) and silane-based additives.

Each of these chemical types offers distinct advantages but also potential drawbacks. This depends upon factors such as mix design, application temperature, environmental conditions and performance requirements.

For example, amine-based additives can enhance workability at lower temperatures, work as an excellent adhesion promoter and

often improve moisture resistance.

Phosphoric acid-based additives act as viscosity modifiers, promoting better mixing and compaction while maintaining high temperature.

Vegetable-based or bio-derived additives are derived from natural oils or fatty acids and are considered more environmentally friendly. They can act as lubricants to reduce viscosity. However, they may have limitations in extreme temperatures or with certain aggregates. The superiority of these additives is that they can be used also as rejuvenating agents.

Meanwhile, silane-based additives, although originally introduced as adhesion promoters, have shown promising results functioning as a WMA/workability aid additive - even for hot mix asphalt applications.

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ROAD SURFACE TECHNOLOGY 2025

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WMA ADDITIVES

The selection of a specific additive depends on multiple factors, including environmental regulations, performance targets, bituminousmixture transport distance and economic considerations. As research continues, hybrid formulations and novel chemistries are also being explored to enhance the effectiveness and sustainability of these multi-functional additives.

SUPERIORITIES The technical, environmental and economic benefits of WMA chemical additives compared to other techniques for reducing the temperature are many and specific. These are...

- Ease of dosage and handling: Perhaps the first superiority of WMA chemical additives over other techniques is the ease of handling and transportation of the materials. Considering the small dosages to be used, even for large-scale projects the overall quantity is far less than for other types of WMA additives;

ABOVE: WMA/workability aid additives for HMA production at 170°C in Sardinia BELOW: WMA/workability aid additives with different chemical nature

- No plant modification needed: Unlike water-based foaming systems, chemical additives are simple to implement.

Using chemical additives does not require any additional equipment; - No specific expertise needed: In addition to foam asphalt plant equipment, the literature has shown that the quality of foamed asphalt highly depends on the technicians’ expertise; - Eliminating the presence of moisture: Different WMA additives lead to different moisture-susceptibility resistance. Only chemical additives can guarantee an adequate moisture susceptibility. Organic waxes and zeolite tend to reduce this property of WMA mixtures². Both plant production and foaming additives could induce moisture into the paving materials and consequent earlystage distress. Hence, it is advisable to use antistripping agents, especially when foaming additives are used. As shown in research³, only chemical additives can guarantee an adequate moisture susceptibility; -Affordability: The dosage of chemical WMA additives in the whole job mix formula (JMF) of any mix is significantly lower compared to organic additives and foaming additives. This low quantity makes these types of additives more affordable for asphalt producers;

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ROAD SURFACE TECHNOLOGY 2025

Test binder

Test method

Bitumen grade 50/70

Bitumen grade 50/70 but with 0.4% amine-based additive

Penetration depth in deci-millimetres

Standard Penetration Test EN 1426

64.5dmm

64.9dmm

Softening point temperature

Ring and Ball Softening Point EN 1427

48.8 °C

48.2 °C

-Unchanged job mix formula: Considering the mechanism of action of certain WMA chemical additives, which function as surfactants and are used in small dosages, these additives do not significantly alter the rheological properties of the binder.

As a result, no modifications are necessary to the existing job mix formulas currently used by asphalt producers. In fact, research has shown that these chemical additives do not remain in the asphalt mixture after compaction is completed4.

In the above table, the insignificant impact is shown of chemical WMA/workability aid additives on the rheological properties of a binder. There is very little depth penetration, as well as temperature change5.

TEMPERATURE-INDEPENDENT ADVANTAGES Since the introduction of WMA chemical additives to the asphalt pavement industry, they have demonstrated a range of benefits beyond simply lowering compaction www.globalhighways.com

WMA ADDITIVES

temperatures. As a result, these additives are now also used in hot mix asphalt (HMA) production for various technical reasons. In such applications, it is more accurate to refer to at least some of them as WMA/workability aid multifunctional additives. Both research and practice have shown additives’ technical advantages. These are: - Enhanced density: The use of chemical additives improves the compatibility of the mixtures and increases the final density of the pavement materials.

According to the literature, even a 1% increase in pavement density can result in a 10% improvement in durability. This can be achieved for both WMA and HMA mixtures⁶; - Rejuvenating for recycled mixtures: Some types of WMA or workability aid chemical additives are formulated for providing a rejuvenating effect in recycled asphalt mixtures - not only in lowering production temperatures and improving workability, but in providing a rejuvenating effect in recycled asphalt mixtures. Certain WMA additives, particularly those of biobased origin, contribute to more sustainable and cost-effective asphalt pavements by allowing for higher reclaimed asphalt content without compromising performance. In such cases, the optimal dosage must be carefully determined to ensure the technical properties are achieved. This dosage may be higher than what is typically used when the additive is applied solely for reducing production temperatures;

ABOVE: Bitumen coverage of problematic aggregates: with amine-based WMA chemical additive on the left and without the additive on the right BELOW: Bitumen coverage of problematic aggregates: with vegetal-based WMA chemical additive on the left and without the additive on the right

- Ensuring the long-distance transport of HMA: The use of WMA or workability aid chemical additives in the production of HMA allows for significantly longer transport distances compared to conventional practices. This is possible due to the enhanced workability of the mixture at lower in situ temperatures, an effect directly attributable to the extended haul duration. For a project on the Italian island of Sardinia, the mixture incorporated 30% reclaimed asphalt without any further recycling agent. The chemical additive was intended not only to enhance the density but also to rejuvenate the recycled material; -Better bitumen/aggregate adhesion: Since WMA chemical additives are mainly of a surfactant nature, their incorporation facilitates better coating of the aggregate particles due to improved adhesion. www.globalhighways.com

ROAD SURFACE TECHNOLOGY 2025

19

WMA ADDITIVES

ADHESION PROMOTER As mentioned, the new developments on WMA/workability aid additives define a variety of functions besides the main task of improving workability and compaction. A study aiming at investigating the potential of improving bitumen/aggregate adhesion - affinity - properties was carried out using two WMA chemical additives. The additives supplied by Iterchimica were ITERLOW

T, an amine-based additive, and ITERLOW ECO, a vegetal oil-base additive.

The dosage of additive was selected based on the TDS (technical data sheet) for producing WMA mixtures. This dosage, which was 0.4% on the weight of bitumen, was higher than the typical dosage for adhesion promoters. Bitumen 50/70, the most common binder for asphalt production in Europe, was used for the base binder.

BITUMEN PENETRATION TESTS Bitumen penetration is a highly critical measure of the hardness and consistency of bituminous material. Bitumen penetration determines the behaviour of a bitumen sample under various temperatures and loads. Correct bitumen selection and testing ensures durability, longevity and performance in diverse environments.

Bitumen penetration test techniques are:

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1 - Standard Penetration Test (SPT) Needle penetrates bitumen for five seconds at 25°C with 100g weight; depth measured in deci-millimetres (dmm) 2 - Ring and Ball Softening Point This tests the softening temperature of bitumen when a steel ball drops through a heated disk of bitumen 3 - Float Test Measures bitumen consistency by time of flotation in water bath 4 - Cone Penetration Test (CPT) Uses a cone instead of a needle for highly viscous bitumen 5 - RTFO Test (Rolling Thin Film Oven) Simulates ageing on mixing and laying by heating bitumen in thin films Penetration grade of bitumen directly influences its applications in road works.

Softer grades with higher penetration values, such as 100/150 or 160/220, are used typically in colder climates where flexibility is required to resist cracking. These grades are used usually as base courses or where low-traffic volumes are present.

Medium penetration grades of 60/70 or 70/100 are more universal and applied for standard road works in non-extreme climates. Meanwhile, due to their superior resistance to deformation, the harder grades with lower penetration values of 30/40 or 40/50 are used in high-temperature regions or for heavy-load conditions, such as highways and airport runways.

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ROAD SURFACE TECHNOLOGY 2025

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WMA ADDITIVES

The test was carried out applying the Rolling Bottle Test (24 hour of rotation), according to the European standard testing methods EN 12697-11 (see box, Bitumenaggregate affinity test).

Using the standard testing method, it was observed that the sample without any additive showed a complete loss of bitumen coverage. In contrast, the sample with the amine-based WMA additive retained over 65% bitumen coverage.

While the vegetal-based additive was less effective than the amine-based one, it still resulted in a significant improvement, achieving 55% bitumen coverage compared to the untreated reference sample.

Overall, the results showed that both types of WMA chemical additives significantly improved adhesion properties and bitumen coverage, demonstrating their effectiveness also as an adhesion promoter. ■ Shahin Eskandarsefat, Ph.D., is a senior researcher at Iterchimica, an Italian global producer of high-tech additives and sustainable technologies for asphalt pavements.

Eskandarsefat specialises in technical documentation, research collaboration and academic activities, including student supervision. Loretta Venturini, Ph.D., is scientific development director at Iterchimica.

She has more than 20 years’ experience in road and airport pavements. https://iterchimica.it/en

BITUMEN-AGGREGATE AFFINITY TEST Adhesion, or affinity, between bitumen and aggregate is paramount because a weak bond results in pavement failure - often premature stripping. Testing to determine adhesion is made on loose and compacted samples. The most common test - because it is simple, fast and inexpensive - is the Rolling Bottle Method, as standardised in EN 12697-11 (part a).

Bitumen-coated aggregates are placed in a bottle which is filled with de-ionised water and then placed in a rolling machine which mechanically stirs the material around in the water. After normally six and 24 hours of this action, two independent operators visually estimate the residual degree of bitumen coverage of the particles.

However, many factors may affect the results, not least because determination of the degree of bitumen coverage is subjective to the observer. The main factors influencing determination are with the operators’ skills, the light conditions and the colour of the aggregates. Dark or grey aggregates, such as basalt or blast furnace slag, may be mistaken for bitumen.

Reference https://www.sciencedirect.com/science/article/pii/S1996681416301043 References [1] Brett A. Williams, J., et al., 2021. NAPA’s Asphalt Pavement Industry Survey on Recycled Materials and Warm Mix Asphalt Usage. National Asphalt Pavement Association.

[2] European Asphalt Pavement Association (EAPA). Technical Aspects of the use of Warm Mix Asphalt. EAPA Technical Review (2022) 45 pages. https://eapa.org/download/17970/?tms tv=1709204907 [3] Frigio F, Canestrari F. Characterisation of warm recycled porous asphalt mixtures prepared with different WMA additives. Eur. J. Environ. Civ. En. (2016) 22 (1), 82e98. https://doi.org/10.1080 /19648189.2016.1179680

[4] Bueche, N., Probst, S., Eskandarsefat, S., (2024). Warm mix asphalt containing reclaimed asphalt pavement: A case study in Switzerland.

Infrastructures. https://doi.org/10.3390/ infrastructures9050079 [5] Bundesanstalt für Straßen- und Verkehrswesen, Projektmappe 140576-4. Available online at: https://www.bast.de/DE/Strassenbau/ Fachthemen/s3-asphalt-erprobung.html [6] FHWA Demonstration Project for Enhanced Durability of Asphalt Pavements through Increased In-place Pavement Density, Phase 3. FHWA-HIF-20-003, Federal Highway Administration.

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ROAD SURFACE TECHNOLOGY 2025

21

COLOURFUL HYDROGEN

HYDROGEN: THE COLOURFUL FUEL

Veidekke Industri*, a major Scandinavian contractor, has been running a Benninghoven MULTI JET burner at its asphalt plant in Ålesund, Norway. CO2 emissions have reportedly

been lowered by 40%, thanks to burning hydrogen, which comes in many colours. or the first time, the use of 100% green hydrogen has been evaluated in the field where Veidekke Industri is using it for asphalt production.

The hydrogen-burning technology comes from Benninghoven, part of the Wirtgen Group which offers a broad spectrum of technologies that drive sustainability in the asphalt industry. Foremost among these technologies is the world’s first asphaltplant burner that can be fuelled using 100% green hydrogen.

Benninghoven has developed a coordinated end-to-end solution for material drying where users can use up to 100% green hydrogen in the production process. The hydrogen-fuelled drying

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ROAD SURFACE TECHNOLOGY 2025

system consists of a MULTI JET burner, a burner-control system and a feed system with a pressure-control section that reduces the hydrogen pressure to the required value for burner operation. Other plant components are adapted as needed to operate with hydrogen. This end-to-end solution connects directly to the hydrogen source, flexibly incorporating various sources such as trailers, supply networks or decentralised electrolysers.

A safety plan is essential when using hydrogen. This was prepared by the ABOVE: The H2-burner retrofit for Veidekke: the first Benninghoven burner in Kristiansund goes on-line (image courtesy Wirtgen/Benninghoven)

specialists from Benninghoven in close collaboration with the Norwegian company. In addition to the reduction of CO₂ emissions, it is also crucial to monitor NOx emissions. The Benninghoven system includes exhaustgas recirculation, which keeps NOx emissions low.

With the hydrogen-burner system, Benninghoven provides a practical solution that offers not only technical but also economic advantages. The ability to switch flexibly between energy sources allows operators to react to market conditions and changing carbon-tax rates.

The resulting reductions of operating costs play an important role in assuring the operator’s future economic viability. www.globalhighways.com

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COLOURFUL HYDROGEN

2024 CLIMATE AWARD “In the past, we assessed where we could reduce CO₂ emissions in our processes as quickly as possible,” explains Eddie Heggard Engebretsen, senior project manager at Veidekke. “For asphalt paving itself, we came to the conclusion that we’d currently be able to achieve reductions of only 3%. But things look very different when it comes to asphalt production. Here, our use of hydrogen already enables us to reduce our CO₂ emissions by as much as 40%.”

Since 2023, Veidekke has been evaluating the technology at its site in Kristiansund, a small port municipality on the western coast of Norway. Several thousand tonnes of asphalt have been produced. Meanwhile, a second plant in Ålesund, around 150km south along the coast, has been running since 2024. The aim has been to validate the process and verify whether a reliable result could be achieved under changed process conditions. This step was crucial, says Engebretsen, for achieving production maturity.

Also in 2024, Veidekke was honoured with the 2024 Climate Award for its work on hydrogen-produced asphalt in Norway.

The award was from the Confederation of Norwegian Enterprises, an employers’ organisation in Norway with more than 30,000 members. Veidekke is already planning to begin production at its next hydrogen-fuelled plant in 2025.

“We consider Benninghoven to be an extremely competent partner for our mission.

Since the commissioning of the MULTI JET burner, we’ve already produced several thousand tons of asphalt using only hydrogen as a zero-emission energy source,” says Heggard Engebretsen.

The use of green hydrogen enables an enormous reduction of carbon emissions in asphalt production. According to latest estimates, around 45% of the carbon emissions in the road-construction-process chain are generated by asphalt-mixing plants, whereby 41% are generated solely by the burner. In view of this, the use of a hydrogen burner is the most effective tool available for the minimisation of carbon emissions.

“Here in the far north, there’s a lot of green energy being generated by hydroelectric power plants (see box). Overall, we must unfortunately say that despite the enormous potential, availability is currently still lagging behind demand,” says Heggard Engebretsen.

“In my view, it can only be a question of time before this is understood and will be appropriately promoted and subsidised.”

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ROAD SURFACE TECHNOLOGY 2025

The ability to switch flexibly between energy sources allows operators to react to market conditions and changing carbon-tax rates (image courtesy Wirtgen/Benninghoven)

“Since the commissioning of the MULTI JET burner, we’ve already produced several thousand tons of asphalt using only hydrogen as a zeroemission energy source” The burner technologies can be installed or retrofitted in new-build and existing asphaltmixing plants from Benninghoven and other manufacturers. The MULTI JET burner can use up to four different fuels at the same time, regardless of their physical state – whether solid, liquid or gaseous. Other features are mixed combustion and fuel-switching on the fly – all without having to shut down the plant or disrupt the production process.

Plant operators, therefore, enjoy a high level of flexibility in the choice of the most economically priced and readily available energy sources. The ability to simply convert plants to the latest burner technologies at any time is an important factor for achieving cost-efficient and sustainable asphalt production, not to mention securing the long-term viability of production sites.

UPBEAT ABOUT HYDROGEN Hydrogen is the energy of the future, Benninghoven said in a written response to questions from RST Review. In the energyintensive thermal drying and heating process of virgin and recycled materials in asphalt production, green hydrogen enables a CO₂-

free operation. Veidekke has taken a lead in this field by showing it understands its responsibility to future generations.

Benninghoven says that its new burner generation is a series-production product that can operate on 100% hydrogen without compromise. Thanks to the new burnercontrol system, customers can use up to four fuels simultaneously and respond quickly to fluctuations in the energy market.

Meanwhile, the new burner-control system means mixed-fuel operation and seamless fuel-switching are possible at any time without shutting down the plant.

As with any technology - especially relatively new technology - safe use is paramount. Benninghoven notes that Veidekke’s safety plan, for example, specifies who is authorised to connect the H₂ trailers to the pressure-regulation system, what training this person must have and what personal protective equipment (PPE) must be worn.

In addition, the plan covers many sitespecific aspects. Which routes do the trucks use to deliver hydrogen on-site? How should personnel respond in the event of a leak?

However, because it is relatively new technology, have there been concerns within the industry about increased risks to personnel operating in a hydrogen-burning environment?

“Quite the opposite, in fact,” says Benninghoven. “We do not see any correlation between safety regulations or plans and potential hesitation on the customer side. We actively support our project partners in developing these concepts and are happy to provide our expertise in an advisory role.” www.globalhighways.com

COLOURFUL HYDROGEN

Safety concepts are standard at asphaltmixing plants, especially when it comes to fuels. Even for conventional fuels like heating oil or liquefied gas, such concepts must be developed, maintained and implemented.

Benninghoven notes that in terms of water protection, for example, the regulatory requirements for an asphalt-mixing plant operating on heating oil are significantly higher than those for hydrogen.

With the technology now proven, the real issue for Benninghoven and other manufacturers of asphalt plants, as well as users of the technology, is a consistent and reliable supply of hydrogen. Benninghoven acknowledges that “availability does present a challenge but it’s not insurmountable”. There is a noticeable increase in the number of suppliers entering the hydrogen market. “As a result, availability is continuously expanding.”

Also on the increase is interest from

potential customers right across Europe where Benninghoven says it has “defined projects and inquiries related to the hydrogen burner”. ■ Benninghoven www.wirtgen-group.com/en-us/company/ benninghoven Veidekke Industri www.veidekke.se/tjanster/veidekke-industri *Veidekke is one of Scandinavia’s largest contractors, undertaking building and civil engineering assignments including maintaining roads and production of asphalt and aggregates.

Annual turnover is around US$3.65 billion.

Veidekke is listed on the Oslo Stock Exchange and has posted a profit every year since its inception in 1936. Half of its 8,000 employees own shares in the company.

KNOW YOUR HYDROGEN COLOURS Hydrogen is the most plentiful element in the universe and offers huge potential as a clean fuel because, when used as a fuel for machinery, the CO2 emissions are simply zero for the most part. However, producing hydrogen is energy-intensive and industrial-scale operations will require major investments in sustainable energy to become cost-efficient.

Hydrogen is often referred to by various colours to indicate origin. Green hydrogen, sometimes referred to as GH2, is hydrogen produced by the electrolysis of water using renewable electricity. Sources include wind, solar, hydro, tidal, geothermal. It may also be produced using electricity from lowemission sources such as biomass. As a result, production of green hydrogen causes significantly lower greenhouse gas emissions than production of grey hydrogen, which is derived from fossil fuels without carbon capture.

Red, pink and purple hydrogen use electricity from a nuclear power plant for the process of electrolysis of water to create the hydrogen. Greenhouse gas emissions here, too, are minimal.

However, grey, black and brown hydrogen all use electricity from a power plant in their electrolysis of water. The greenhouse gas footprint is from medium to high. But, if most of the carbon dioxide emission is captured, the resulting hydrogen can be referred to as blue hydrogen.

Heidecke’s Ålesund asphalt-mixing plant with a Benninghoven MULTI JET burner has been in production since October 2023 (image courtesy Wirtgen/Benninghoven)

www.globalhighways.com

ROAD SURFACE TECHNOLOGY 2025

25

BITUMEN DEMAND

© Bogdanhoda | Dreamstime.com

THE BITUMEN BLUES For at least the next decade, bitumen-production capacity will be shrinking but bitumen demand will be rising, explains John Read. He examines what could make the situation worse but also what the industry can do to close this looming gap. learly there is a need to reduce the world’s dependence on fossil fuels to meet the aspirations of the Paris Accord, signed in 2015 by 195 countries. The goal is to limit global warming to well below 2ºC, preferably to 1.5ºC, compared to pre-industrial levels.

Where does this leave the supply and demand for bitumen, especially in a world of shrinking bitumen-production capacity?

By 2035 - depending on the predictive models used - the demand for bitumen will be between 140 million tonnes (Mt) and 160Mt. Demand is currently growing at a compound annual growth rate (CAGR) of around 3%.

At the same time, the refining capacity for bitumen is reducing. Today, available supply is around 110Mt with 26 of 100 refineries in Europe closing since 2019. Over the same time period, around 10 US refineries closed, with the combination reducing available bitumen supply by about 10Mt. Looking ahead, the International Energy Agency estimates that a further 10Mt of bitumen capacity may disappear.

This means that by 2035 the gap between supply and demand could be as wide as 50Mt. This is without factoring in any geopolitical issues which either stop crude from flowing, change the routes it takes or make it unaffordable.

These geo-political issues could be sanctions against countries such as Russia, Iran and Venezuela which produce heavy crude, a high bitumen yield. It might be trade agreements such as the Chinese buying up all the good Maya and Isthmus bitumen crudes from Mexico or disruptions to key trade routes that have pinch points such as the Suez and Panama canals, as well as the

C

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ROAD SURFACE TECHNOLOGY 2025

Strait of Malacca. Possibly more tariffs could be imposed such as those by the US upon countries including Canada; America’s largest trading partner is now looking to move its heavy oil to Europe rather than by pipeline into the US. When you add in environmental pressures to all this, there is a fundamental need to reduce demand for bitumen and to find an alternative that will be sustainable, environmentally friendly and circular.

In terms of reducing demand there are three principle ways to do this: - Change the mixture type/design - Add more Recycled Asphalt Pavement (RAP) - Make longer-life pavements In terms of changing the mixture type and demand, we would need to go to coarser, larger stone mixtures. But these carry their own issues in terms of compactability, segregation, stone crushing and waste generation, ride smoothness, noise generation and more. Even if all these things were overcome, the reduction in binder demand would be only about 10%, or in today’s terms maybe 8Mt globally.

Adding more RAP is always cited as a solution, or at least part of the solution.

However, there are a number of issues when increasing RAP content. One is the availability of RAP. Looking at the figures globally, we are using just about the same amount of RAP that we are producing, meaning RAP stockpiles are not changing year-on-year. So, there really is not an awful lot more RAP, on average, globally. That is, unless we make more, which sort of defeats the object of the exercise. In addition, developing nations are

still building their road networks and as such are not generating RAP, meaning all their road construction needs to be done with 100% virgin material.

Another issue is the quality of RAP. Currently, we use on average 15-20% RAP in our mixtures. We can consider all the binder in the RAP to be useable as there is sufficient “performance reservoir” in the 80-85% virgin binder that is added to overcome any deficiencies in the RAP. However, if you push beyond 20% RAP, then the oxygen uptake in the asphaltenes in the aged binder in the RAP becomes critical. When oxygen uptake is beyond 5%, then RAP can really be considered as black rock with no useable bitumen. In this case, it can still be used, but 100% virgin binder addition is required to obtain the desired performance.

There is also the issue of using recycling/ rejuvenating agents. This may be helpful in the future but they need to be true rejuvenators that rebalance viscosity, as current recycling agents do. However, and much more importantly, they must rebalance the chemistry of the binder. Today most, if not all, are really recycling agents that only rebalance viscosity. This will simply create a negative legacy with which future generations must deal.

Making longer-life pavements is without doubt the best transition solution while we are developing the binders of the future.

We already know how to do this. Balanced mixture design enables use of local resources - sand, aggregates, filler, crushed rock fines and RAP - rather than hauling raw materials long distances and incurring transportation costs and CO2. Intelligent compaction ensures optimum asphalt-mixture volumetrics according to the balanced mixture design. www.globalhighways.com

BITUMEN DEMAND

Bitumen emulsifiers market size, by type, 2021-2034 (USD Billion)

Meanwhile, bases that never need replacing keep tensile, compressive and shear stresses/ strains below critical levels through SMART monitoring solutions. These solutions can be: - Satellite imaging and AI - Full traffic-speed monitoring with automatic failure-mechanism data analysis - Image analysis on cracking - Laser rut-depth measurement - Falling-weight and heavy-weight deflectometer structural analysis - Ground-penetrating radar to assess condition of sub layers - Higher quality testing of all components to allow for their optimum usage - Surfaces that last longer than the average of around 12 years - Modified asphalt surfaces to increase performance: l Fibre, such as aramid, reinforcement to increase life l Renewable polymers with much lower carbon footprint such as graphene from recycled plastic l Renewable waxes with much lower carbon footprint such as from recycled plastic to both improve performance and reduce construction temperatures (lower CO2) If we do all of the above, we might be able to reduce the shortfall by 20Mt. This leaves another 30Mt just to stand still during the transition and 130Mt to find to completely replace fossil-based binders.

When looking at the scale of the replacement that is required there is only one bio-material (low or even negative CO2) that does not compete with the food chain. This is lignin.

Lignin is the part of the plant that is generally wasted when we either make food or bio-refine to produce sugars and, from that, ethanol for fuels. There have been many trials of bio-based partial substitutes for bitumen. These include using kraft lignin - sometimes called tall oil, liquid rosin or tallol – which is produced from kraft pulping/sulphate pulping of wood. Other trials have used rapeseed oil, refined used cooking oils, cashew nutshell oil and certain eco-certified palm oils. When you add all of these together at their maximum amounts you would get less than 5Mt. We are then faced with needing a much more voluminous, environmentally friendly and sustainable alternative.

The problem is that lignin is not a binder.

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ROAD SURFACE TECHNOLOGY 2025

115.6

122

129.1

136.7

2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 Cationic emulsified bitumen Non-ionic emulsified bitumen

Anionic emulsified bitumen Modified emulsified bitumen

Source: www.gminsights.com

Bitumen market size, by product type, 2021-2032 (USD Billion)

51.7

53.9

56.1

2021

2022

2023

2024

2025

Paving grade bitumen Polymer modified bitumen (PMB) Emulsion bitumen

2026

2027

2028

2029

Oxidized bitumen Bitumen additives Other (e.g., cutback bitumen)

When processed it is typically a dry powder.

There have been many attempts to use the lignin in a dry process by just adding it to the asphalt. When you get up to about 20% lignin content into the asphalt, the lignin behaves simply like a functional filler at best. At worst, it acts as just a filler with no incremental properties but demands more bitumen to deliver the required performance from the asphalt.

Therefore, we need a way to turn the powdered lignin into a liquid binder through some form of post processing that does not offset the CO2 benefits of a bio-binder. Nor should it exceed the cost of conventional fossil-based bitumen. This is where R&D needs to be focused over the coming few years. If we can achieve this then we will have seen the ‘third coming’ of a flexible binder for road construction that is circular and in this case both environmentally friendly and sustainable.

Encouragingly, we as an industry, have many of the tools to make the necessary changes. But my question is this: are we ready and willing to do what is necessary to deliver what is required? ■ https://bitucore.com

2030

2031

2032

Source: www.gminsights.com

John Read has worked in the bitumen and sulphur industry for nearly 40 years. He retired from Shell at the end of 2024 as the global head of technology and general manager for Shell Specialities (Bitumen and Sulphur).

He recently set up an industrial bitumen manufacturing business, BituCore, based in Texas, as well as a consultancy, Bentley Bitumen. He has delivered more than 150 public presentations and published more than 100 papers, articles and technical brochures, including the Shell Bitumen Handbook (5th and 6th editions). He has been vice president of Eurobitume, served as Shell’s primary director on the Asphalt Institute (US) for 20 years and sat on the Council of the Institute of Asphalt Technology (UK).

The views and ideas expressed are solely those of the author. www.globalhighways.com

INTELLIGENT PAVING

PAVING: THE 3D MODELLING WORKFLOW

Integrated digital workflows are defining the new baseline for road-surface technology, explains Kevin Garcia, general manager of civil specialty solutions at Trimble. he paving industry is in the midst of transformation, moving beyond incremental gains in efficiency to full-scale precision driven by integrated digital workflows.

Leveraging technology to maximise output and quality has become paramount as global pressure mounts to maintain existing road networks in the face of budget constraints.

This transformation centres on how civilconstruction solutions connect the entire project lifecycle - from the earliest days of bidding through final-project verification - to deliver verifiable, millimetre-level paving accuracy.

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Connected workflows eliminate typical bottlenecks such as the spreadsheet-driven process that connects estimating to field operations. Instead, construction software creates a direct data flow from bid to blueprint and on to field execution and project completion. The data bridges the gap between design, pre-construction and field execution. This establishes a single source of truth that provides field crews with up-to-

date design information and site conditions in real time. Project teams can verify volumes and confirm surfaces to meet tolerance specifications.

This digital-verification loop transitions quality control from a reactive, postconstruction testing approach to a proactive methodology where crews adjust operations based on quantifiable data.

ACCURACY AND SURFACE SYMMETRY Central to the field execution phase is implementation of 3D machine control which has fundamentally reshaped conventional paving and grading.

Trimble Roadworks’ paving-control platform automatically guides the milling drum to cut the ideal depth and slope, with quality assurance confirmed by a grade-checker leveraging Trimble Siteworks software (image © Trimble)

www.globalhighways.com

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The Trimble SPS930 universal total station provides high-accuracy positioning information for the mill, which is guided by Trimble Roadworks paving-control platform (image © Trimble)

Solutions designed for civil specialty construction enable contractors to achieve surfaces that meet or exceed stringent requirements, such as those guided by the IRI (International Roughness Index).

Key components for achieving this precision include: • Universal total stations (UTS): Systems using a UTS can achieve high-precision measurements, accurate to around +/3mm horizontally and +/-1mm vertically.

The instrument acts as a survey tool and machine-control guide.

• 3D modelling guidance: Motor graders and milling machines with 3D guidance know exactly where they are and what they are cutting. This technology drives execution, analyses the amount of material to lay and provides seamless guidance for the operator.

• Eliminating obstacles: A practical benefit is the elimination of traditional survey stakes and string lines, making the jobsite safer.

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RABINE PAVING Rabine Paving is a full-service pavement maintenance, design, construction and construction-management firm. It specialises in large, commercial and industrial parkinglot and utility-restoration projects. Rabine adopted a paving-control platform for its mills and cold planers.

“When it comes to pavement restoration, surface smoothness, drainage and ADA adaptations are the primary challenge,” says Kyle Miller, director of operations at Rabine.

“We have great operators who are able to adjust to these complexities and deliver optimal results, but we’re always looking to give them every advantage.”

A visual display of the 3D design shows the operator a comparison of the actual drum position and slope against the ideal grade. The system then automatically guides the milling drum to cut the defined depth and slope without the need for manual adjustments or string lines. A parking lot with complex slopes and a roundabout proved the system’s ability because the software automatically and quickly adjusted to the required radius. Automation allows

the operator to focus on critical decisions.

One operator noted the 3D mill technology allowed him to complete the job with increased speed and accuracy.

The 3D milling workflow is straightforward: data collected from the site (edges, curves, basins) is used to create 3D milling plans. This allows for in-field decisions and the ability to verify that it has slopes that are ADA-compliant (Americans with Disabilities Act) ahead of production.

This investment ensures smooth profiles with minimal waste - even in the most complicated lots.

JORGE CHÁVEZ AIRPORT A new 270,000m² modern passenger terminal at the Jorge Chávez International Airport in Lima, Peru, required placing 70,000m³ of concrete and asphalt for the airside airplane-parking areas around the terminal. “One of the main concerns was synchronising design data and information flow between the field and office,” says Carlos Ruiz Miranda, chief surveyor with SACYR, a construction company based in Spain. www.globalhighways.com

INTELLIGENT PAVING

Implementing a cloud-based common data environment (CDE), Ruiz created a centralised collaboration platform. Design data moved automatically from development of a building information model (BIM) through remote data-transfer software to machine-guidance files on graders and pavers. Real-time field data flowed back through jobsite productivity-tracking software, creating predictive capabilities that optimised resource allocation. The team used machine control for base and subbase layers, paving 1cm accuracy, well below the 1.8cm requirements. This integrated workflow achieved zero non-conformities from the client.

BUCK BROTHERS Buck Brothers, based in Toledo in the US state of Ohio, struggled with manual methods for fine grading stone base, calling it “guessand-check”. However, they implemented a workflow using a UTS and 3D modelling software. On a 100,000-square-foot parkinglot reconstruction, the crew regraded the area to a precision of 1/16. The finished surface, working directly from as-built conditions, ensures drainage and transitions are exactly right.

In just two months, the company was able to fine grade more than 300,000 square feet of stone base, cutting preparation time in half. Knowing everything paved is at the right thickness and will drain correctly means greater materials efficiency.

Precision achieved through connected workflows delivers multiple downstream benefits. For example, using a 3D modelling workflow ensures contractors are not “over on asphalt”. The precision maximises material yield and prevents overuse. Leading contractors track a 10-20% material-waste reduction. The system can be used for subgrade or finished grade to guarantee yield and help manage costs.

Another benefit is through proactive risk prevention. 3D machine guidance keeps surveyors and crews away from active equipment and live traffic. Thanks to digital ticketing platforms, field personnel no longer approach trucks to collect paper tickets, thus reducing close-quarter interactions in high-risk areas. Furthermore, eliminating traditional string lines removes a significant tripping risk.

Precision placement means getting the work right, first time. For ongoing quality control, infrared camera technology on pavers monitors mat temperature to ensure material is within the correct temperature www.globalhighways.com

ABOVE: Using a 3D modelling workflow ensures contractors are not “over on asphalt” (image © Buck Brothers)

window for compaction. These advances boost efficiency. They also offset the skilled labour shortage by automating repetitive tasks and allowing operators to focus on critical, judgement-based decisions. Contractors also note the use of 3D technology as an important element in workforce development, helping bring new or less experienced operators up to speed more quickly and thus attracting new talent who wish to work with the latest technology.

COMPETITIVE ASSET For Rabine, the commitment to 3D milling solutions represents not only a road to efficiency, but an important element in the contractor’s workforce development. Miller stated that technology allows the company to be more competitive because of increased production.

Beyond the immediate execution phase, 3D milling provides detailed, as-built conditions data. This data provides lasting value, especially considering that the company earns much of its work from repeat customers. If Rabine has milled a particular site in the past, they already have a surface file that they can reference. This practice of using completed survey models and as-built data to inform more accurate future estimates is a core

ABOVE: Buck Brothers implemented a workflow using a UTS and 3D modelling software for a major parking-lot reconstruction, doing away with ‘guess-and-check’ for the fine grading stone base (image © Buck Brothers)

benefit of digital transformation.

Miller also sees investment in pavingcontrol technology as a key step toward Rabine expanding its services, particularly into new construction. The value of the solution extends beyond the mill, with Miller envisioning its use for subgrade or finished grade as a way to guarantee yield and improve quality. ■ Trimble www.trimble.com/en

Kevin Garcia is general manager of civil specialty solutions at Trimble where he leads innovation for road-construction applications.

He has extensive experience in machine control, digital workflows and construction automation.

Garcia works directly with contractors and departments of transport to implement safety and efficiency improvements on paving projects across the globe.

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BITUMEN

Every tonne of bitumen delivered involves energy-intensive shipping and trucking (image courtesy Nynas)

n independent study has shown significant and immediate sustainability gains can be made by sourcing bitumen from suppliers with geographically closer depots and refineries.

The road sector is under increasing pressure to deliver infrastructure that meets high-performance standards and aligns with climate targets. While the industry continues to explore long-term shifts such as electrification of equipment, recycling of asphalt and alternative binders, immediate gains are available through smarter logistics.

The study, carried out by Future Earth Analytics and commissioned by Nynas, compared the environmental impact of transporting bitumen from Nynas’ refineries with market alternatives in Scandinavia, Finland and the UK. Using one tonne of bitumen delivered to a city centre as the baseline, the analysis combined GIS (geographic information system) modelling with maritime and roadtransport data. Routes were mapped with ArcGIS Pro*, while energy and emissions factors came from the ecoinvent 3.9.1 database. Both shipping and trucking stages were included, with vessel-size differences accounted for. The study calculated and compared energy demand (CED) and greenhouse gas (GHG) emissions (GWP100) for Nynas versus competitors.

The results show that the logistics of bitumen distribution can significantly reduce energy use and GHG emissions. The analysis compares Nynas’ distribution system with those of major competitors in Scandinavia, Finland, and the UK. It provides quantitative

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SAVING WHEN PAVING

Sourcing and delivery of bitumen can be overlooked when it comes to focusing on sustainable road construction. It matters from where and how the material is procured, says Marika Rangstedt and Carl Hultin of Nynas.

evidence of how logistics choices can directly affect the sustainability and quality of road projects.

“This study makes clear that where bitumen comes from and how it reaches a road surface really matters,” says Marika Rangstedt, sustainability manager at Nynas.

“For an industry tasked with balancing performance, cost and environmental responsibility, this insight provides a practical path toward more sustainable paving.”

Every tonne of bitumen delivered involves energy-intensive shipping and trucking steps. Even modest differences in supply routes can translate into major variations in environmental performance.

“Used in huge quantities on roads, bitumen is best sourced locally, limiting the cost and environmental impact of transport.

This study confirms that our regional production and distribution model results in measurable energy and emissions savings compared to market alternatives,” notes Carl Hultin, marketing manager for bitumen at Nynas.

By comparing Nynas’ depot network with the nearest competitor depots, the study isolated the logistics-driven differences in transport energy and GHG emissions. The findings showed reduced transport-related energy use by between 50 and 940 megajoules per tonne at deliveries to large cities. Savings were up to 1.2 gigajoules per tonne in smaller municipalities.

Regarding emissions savings, deliveries saved up to 91kg CO2eq per tonne compared with competitors.

As well, it showed energy savings for deliveries to 74% of cities in Scandinavia, Finland and the UK. GHG savings were recorded for nearly 80% of locations.

When it comes to shipments by sea - and despite using smaller vessels - Nynas still has an energy advantage to 90% of towns and cities, thanks to the shorter distances between refinery and depots.

In practice, these figures scale up rapidly. “Transport is sometimes overlooked when evaluating the sustainability performance of materials. www.globalhighways.com

BITUMEN

Efficient logistics translate directly into lower emissions and energy use - benefits that road authorities and contractors can factor into their own sustainability strategies,” says Rangstedt.

The analysis shows that procurement decisions can have significant downstream effects. While asphalt-mix design, recycling and innovative binders are all important, upstream-sourcing choices can add another lever for emissions reduction without compromising quality or performance.

For road agencies and contractors, the study provides actionable insights surrounding: • Environmental impact - logistics-related energy consumption and emissions may not always be fully accounted for, but can represent a significant share of the overall environmental impact of the material.

• Regional supply advantages - sourcing from suppliers with geographically closer depots and refineries can provide verifiable sustainability gains.

Marika Rangstedt has more than 25 years of experience in specialty oil products and their applications. At Nynas she has held various positions within R&D, product development and technical marketing and for the past 10 years has focussed on sustainability. She holds an MSc in chemical engineering from the Royal Institute of Technology in Stockholm.

• Alignment with climate targets with European Union and national commitments to cut transport and construction emissions, procurement processes that integrate logistics-based impact assessments can demonstrate compliance and leadership. ■

Carl Hultin has a decade of experience in the bitumen industry and is now marketing manager for bitumen at Nynas. With a strong background in both technical and commercial roles, he focuses on endorsing solutions that enhance infrastructure performance while supporting the transition to a more sustainable future. He holds a BSc in chemical engineering.

Nynas https://www.nynas.com *Built by Esri, ArcGIS integrates and connects data through the context of geography. It provides capabilities for creating, managing, analysing, mapping and sharing all types of data.

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ROAD SURFACE TECHNOLOGY 2025

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INTELLIGENT PAVING

A SMOOTHRIDE ON CHARLESTON’S I-526 In the US state of South Carolina, the SmoothRide paving solution from Topcon Positioning Systems converted the sceptics working on the I-526 loop around Charleston. anks Construction is no stranger to paving excellence. Work by the Charleston, South Carolina, company is regularly on the South Carolina Asphalt Paving Association’s list of award-winning projects. Banks is, in fact, one of the region’s most in-demand asphalt-paving specialists.

One major interstate-resurfacing project, in 2023, was of particular importance for the company, more for the sense of accomplishment than for the accolades.

Banks - never a business to shy away from adopting the latest technology - used a paving solution touted as ‘intelligent’. Some key team members were sceptical at the outset. Regardless, the company put the solution to the test on one of Charleston’s highest profile thoroughfares. By project’s end, the sceptics were true believers in the new paving approach.

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The project was 32-lane/miles of resurfacing that included seven bridges along an eight-mile section of the heavily travelled I-526 loop around Charleston.

Even before securing the bid for the job, a serious concern was noted, according to Banks’s survey manager Trey Cox, an accredited PLS - Professional Land Surveyor.

“We had completed a similar job for the department of transportation a while back and, because of the way we had to do it, it proved a disappointment for everyone,” he said. “That was a two-stage milling operation which called for the surface to

be milled, then surveyed to get the design needed for correction, then milled again to match that correction. The problem in this part of the country is that, once you mill a surface - even when you micro-mill it - between the moisture and the cold temperatures we can get, the milled surface tends to crumble. That increases the risk of motorist claims, which we always want to avoid. We knew we couldn’t tackle the I-526 job using the same techniques.”

Banks turned to a revolutionary solution from Topcon Positioning Systems called SmoothRide, which the company had seen at CONEXPO-CON/AGG, the triennial construction trade show in Las Vegas*.

The project was 32-lane/miles of resurfacing that included seven bridges along an eight-mile section of the heavily travelled I-526 loop around Charleston (image © Banks Construction /Topcon Positioning Systems)

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www.globalhighways.com

INTELLIGENT PAVING

Because it would enhance the entire workflow of their asphalt operation, from highway-speed road scanning to variabledepth milling to 3D paving and more, Banks’s management felt it was the solution it needed.

A TRUE CONVERT Cox was initially sceptical about SmoothRide, specifically about its ability to provide a profitable result on the project. But Banks’s management felt it was the right move to make. With its blessing, Cox and his team set to proving it out.

“We had Justin Thompson, one of Topcon’s intelligent paving specialists, come to our office where we talked a bit about the system, used the Topcon RD-M1 to scan a portion of I-26 and set a time for a demonstration,” said Cox. “We had 25 trucks lined up, two mills and a full paving crew. Even though we did a very basic scanning session and job setup, it worked to perfection. At that point, I was all in for the 526 job.”

Banks went back to the DoT with a bid, now substantially lower because of the savings they knew they could reap by streamlining the workflow.

“Because the full milling operation can be done at the same time as paving, the cost savings are substantial,” said Cox. “You’ve reduced milling time, minimised the need for traffic-control trucks, etc. And less www.globalhighways.com

time on the interstate reduces our safety exposures. So, we had DoT engineers come down, showed them the technology, and laid out what we planned for the project. One point of contention was that some of the specs called for actual true elevations rather than relative ones. However, with a simple update to SmoothRide’s software, we pulled that info directly from either a control file or the Geoide file. They walked away happy, knowing they were saving money, and we would get the job done quickly.”

While Cox values every facet of the SmoothRide process, he finds particular appeal in the scanning aspect. This is where Banks has found most benefits. “SmoothRide provides what the paving industry has been wanting for years, the ability to see what we are going to get into before getting into it,” he said.

“A company like ours can get a milling job or a slope-correction project and survey it, giving us a pretty good idea of what’s needed.

But we can never really know exactly what will happen until we get out there. This technology changes all that. We could go in and, once we set up our parameters - max mill of four inches, minimum mill of one inch - we could go through the design and see areas where we were either going to be deep or ‘daylighting’, then modify those areas to fix them.”

ABOVE: SmoothRide enhanced the entire workflow of their asphalt operation, from highway-speed road scanning to variable-depth milling to 3D paving and more (image © Banks Construction/Topcon Positioning Systems)

SmoothRide has already proven itself to be an outstanding milling and paving solution that, to date, has hardly scratched the surface of what can be done. “With the RD-M1 scanner, which is the initial step in the SmoothRide process, we see a real benefit in scanning roads for as-built information,” he said.

“We regularly bid on jobs that were surveyed and designed five or six years previously. In that time, that road’s already been overlaid maybe a couple times but needs to be resurveyed because the design says, ‘match existing’. Using the RD-M1 to do that, not only eliminates the cost of lane closures but keeps a survey crew off the road.

The safety factor it provides was almost as important in our decision-making process as streamlining the workflow.”

RETURN ON INVESTMENT The savings realised through the elimination of one complete milling run on an eight-mile, four-lane project can be substantial. This was proven on the I-526 resurfacing. “First and ROAD SURFACE TECHNOLOGY 2025

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foremost, we cut 20 shifts out of the job by not having to mill ahead of time,” he said.

“That’s a significant saving in per-night costs.

Being able to gather as-built data while out there, rather than at the end of the project, was also huge. And there’s simply not a way to put a number on the safety and liability.

I don’t believe we had a single claim on this job, which is almost unheard of for an Interstate project. Given all that, our owners believe SmoothRide was well worth the investment.”

Though it’s sometimes overlooked, a reduction in environmental impact by streamlining a project’s workflow can be quite compelling. According to Cox, those savings were literally across the board on the I-526 project. “Each one of the 20 tri-axle trucks working for us probably burns 25 gallons of diesel fuel per night and that was with a shorter discharge run,” he said.

“That’s easily 10,000 gallons of fuel that wasn’t used and which didn’t create emissions. And a Wirtgen 220 mill uses its fair share of diesel as well, adding to that consumption total. When you can cut days or

shifts off of a job, the impacts in so many areas can be just staggering.”

As cited in Banks’s South Carolina Asphalt Paving Association award, by the time the I-526 resurfacing project was completed in October 2023, 42,826 tons of asphalt had been placed over the eight-mile section of the project. SmoothRide benefits read like a laundry list, according to the award notes, saying that the Banks team used new technology for all the work to be performed in one operation. This resulted in significant savings for the DoT. In addition, the scope-change significantly reduced project time and eliminated any exposure to a milled surface, both of which minimised the overall impact on the travelling public. The final results were an average rideability improvement of around 30%.

“What the award doesn’t show is that we had to meet some very stringent cross-slope correction specifications,” said Cox. “I’m extremely proud of the work our team did on the I-526 job and am glad that they were able to share in this award. We, as a company, are also very grateful for the support we get

from Randall Brown at Georgia Surveyors Exchange, our Topcon dealer. And we can’t say enough about Topcon and the solutions they continue to provide. Performing a job in 300 days, when it was bid for 360 days, significantly enhances the safety of our employees and that of the travelling public.

That’s another reason we’ve partnered with Topcon for some 16 years now.”

As to who were the real winners of the award, Cox is adamant. “I’d have to say it’s the Charleston-area residents who regularly travel the I-526 daily. They’ve got something they’ve missed for some time - a truly, truly smooth ride.” ■ *The next CONEXPO-CON/AGG will take place in Las Vegas in the US state of Nevada, from March 3-7, 2026: www.conexpoconagg.com Topcon Positioning Systems www.topconpositioning.com Banks Construction www.banksconstruction.com

Thompson: from a DoT perspective, there can be a “wow factor” when they see Topcon Positioning System’s Resurfacing software in action (image © Banks Construction/Topcon Positioning Systems)

“When you can cut days or shifts off of a job, the impacts in so many areas can be just staggering”

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www.globalhighways.com

INTELLIGENT PAVING

TRUST AND PARTNERSHIP

Matt Kohler and Justin Thompson, from Topcon Positioning Systems, explain how SmoothRide can lay the foundations for a long-term, contractor-client partnership. he award-winning I-526 work

by Banks Construction in South Carolina showcases how SmoothRide technology is a gamechanger for road-maintenance projects.

For both contractor and client, the benefits are time-savings on site which translate directly into financial savings, as well as material savings, which also translate into financial savings. Apart from these concrete, measurable benefits, there is another overriding benefit, again for both client and contractor. SmoothRide lays the foundation for a lasting and trusted partnership; a winwin situation, says Matt Kohler, vice president of strategic initiatives for North America, Latin America and Oceania. But how did SmoothRide, the idea, come about?

“When paving, you’ve got cross-slope correction, matt or material thickness and then you have rideability,” he says.

“Traditional paving is 2D, whether contractors use a string line or a sonic tracker, they can give you one or two of those.

They can’t give you all three with any real solid results. How can we correct this? By using a downward-facing LiDAR scanner and implementing a software called Resurfacing - that’s really the secret sauce to this whole thing. Then we put our 3D machine control to use, using our GNSS control, along with incorporating our sonic trackers into a product.

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www.globalhighways.com

“So, we are actually reading the ground in real time for vertical elevation while the GPS is giving you positioning and then it is comparing it to whatever design you have done for the resurfacing model. That’s how you’re getting your true corrective action and we’re able to achieve very real variable depth paving or milling.”

Many road contractors’ bread and butter is in maintenance, and not in the construction of a road, notes Justin Thompson, an intelligent-paving specialist at Topcon Positioning Systems. SmoothRide is targeted for maintenance projects, which account for 95% of what a DoT typically contracts out every year. Mill-and-fill overlay projects make up the bulk of this. It’s not geared towards elevation, it’s geared towards crossslope, ride specifications and road thickness.

“It doesn’t really change the operator’s day-to-day value,” says Thompson. “So, we still use the same sensors that they use every day for paving and milling that we use on 2D systems. We use it on our 3D systems.

So, their operational values of what they do stay the same, but we just use the GNSS for location and those same sensors for the grades.”

Some competitors are coming along right now, but Topcon remains in the forefront of this technology. It’s one thing to build a perfect road but it’s another thing to make that road perfect again. The contractor

Thompson acknowledges that real benefits from SmoothRide are to be found on larger resurfacing work (image © Topcon Positioning Systems)

may not be working with a perfect base anymore. There are a lot of variables, explains Thompson.

For the I-526 work, Banks scanned the existing road and realised that the details and plan given to them by the DoT were not accurate. The road was supposed to be at a 2% crown but their RD-M1 scanner showed it was actually super-elevated, one side to the other. This completely changed the design of the project work. Thompson said Banks, to be certain, came to him to double-check the results. “We were right on the money,” says Thompson. “So they went back to the state DoT with the scanner’s results and said there was no way to correct this job per your plan specification.”

To avoid completely pulling the project and having to undertake a whole resurvey and redesign of the road, which would probably have taken another year, they allowed Banks to redesign the project themselves, using their data capture. Another time and money saver, notes Thompson. Banks was, of course, paid for time and material but the savings to the DoT were, he believes, in the order of a million dollars or more. “I heard this directly from the owners at Banks. They couldn’t be more happy with it, as was the state of South Carolina.”

The important point here is that both contractor and DoT were seen to be working in extremely close partnership. Both organisations owned the project. “Instead of arguing and fighting it out, they both came to an understanding that this is the best solution. We’ve seen this time and again with SmoothRide, where the contractor wants to deliver the most high-value, high-quality ROAD SURFACE TECHNOLOGY 2025

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product that they can to their DoT. And the DoT needs the problem solved but must work within financial constraints,” says Thompson.

“It’s a consultative relationship.”

It leads to what might be called a virtuous circle, where the DoT sees the results of working with SmoothRide. “Once we get that first project accomplished, typically what happens is the DoT acknowledges that SmoothRide is a very, very viable solution and they actually encourage their contractors within their area to start using it more on different projects.”

Also, from a DoT perspective, says Thompson, there can be a “wow factor” when they see Topcon Positioning System’s Resurfacing software. “This is because DoTs are so software-design heavy, they typically use Bentley products for that, which are very, very good solutions. But then they see the Topcon Resurfacing module and how easy it is to use. We’re simply entering the specification data into a database inside of our software and it spits out exactly what that road’s going to look like per the DoT’s specification, on top of that scan data. It’s a quick process of entering cross-slope values, IRI values, the debt values that you want. It really does blow their mind.”

Even so, Thompson acknowledges that the real benefits from SmoothRide are to be found on larger resurfacing work. “We’re really all about correcting long longitudinal wavelengths. So, you’re probably looking at a minimum half-mile contract. Of course, you can use it on 500 feet if you want. But you’re not going to get the value for which you bought the system.”

ABOVE: SmoothRide reads the ground in real time for vertical elevation while the GPS gives positioning (image © Topcon Positioning Systems)

The benefits will come tumbling in on projects that cover, say, several miles or major airport-runway revamps. This is because SmoothRide is a “volume cruncher”, says Kohler. “The more miles you can correct using it, the more money you can save. It really is a force multiplier where savings rise exponentially.”

Overall, SmoothRide offers both contractor and client – and road user – the certainty and comfort of as near a perfect road surface as you can get, says Thompson. There is no guesswork anymore. “With SmoothRide, we capture the existing data and we apply those corrective actions on top of that virtually, in a model, so we know.”

Certainty and comfort, thanks to no guesswork, is what cements that long-lasting partnership between contractor and DoT. “Absolutely,” says Kohler. ■

Matt Kohler is a graduate of Fort Lewis College, a public liberal arts college in Durango, Colorado. He has been in the positioning industry since 1993 and joined Topcon in 2011 where he has held several management positions. These include managing distribution as a regional sales manager, serving as a senior strategic-partner manager working with regional, national and global accounts, and overseeing Topcon’s Construction Business Unit for Western North America. Kohler is currently vice president of strategic initiatives for the Americas and Oceania regions within Topcon Positioning Systems, based in Livermore in the US state of California. He leads several business-development teams, focusing on growth strategies across key areas, including intelligent paving, compact-machine control, strategicpartner development and governmental engagements.

Justin Thompson has 15 years of extensive construction experience, having worked as a land surveyor, field engineer, survey manager, foreman and superintendent. His projects have included concrete bridges, water-treatment plants, and mainline road construction where he developed skills in building digital terrain models and using machine control. Prior to joining Topcon Positioning Systems, he was an inspection engineer for the North Carolina Department of Transportation. He is now an intelligent-paving specialist serving as a regional sales manager for Topcon asphalt-paving technologies. He oversees the southeastern region of the US and all of Canada, assisting Topcon dealers with the education, training and sales of asphalt-paving technology.

LEFT: SmoothRide is targeted for maintenance projects, which account for 95% of what a DoT typically contracts yearly, and focuses on crossslope, ride specifications and road thickness (image © Topcon Positioning Systems)

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www.globalhighways.com

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THE PROMISE OF LIGNIN CONTINUES

Research continues on lignin as a partial substitute for asphalt binder. Kait Kaarel Puss and Karli Kontson review where the industry is at and where it is going.

or several decades lignin, as a partial replacement for asphalt binder, has been the focus of many studies, including one of the first commissioned by the Federal Highway Administration (FHWA)in the United States in 19801. The FHWA study concluded that lignin is a promising raw material for the partial replacement of asphalt binder. With replacement rates of up to 30%, it is possible to ensure that the asphalt mixtures meet required specifications.

At that time, the study was initiated due to the limited availability of binder and its steadily rising market price which was forcing the sector to consider alternatives. Depending on the region, availability and especially price can still be an issue today. But in recent years, a driving force for considering lignin as a partial replacement for binder has been the road-construction sector’s concern about the environmental impact.

Given that, during the past 10 to 15 years, interest in lignin as one potential binder substitute has grown exponentially2. The main driving factor is the global sector’s pursuit to reduce the environmental footprint of construction products by increasing the share of carbon-sequestering, bio-based raw materials in end products and reducing the share of fossil-based bitumen.

F

Asphalt mixtures generally consist of about 5% bitumen and about 95% aggregates.

Nevertheless, the environmental footprint of asphalt mixtures is relatively high, typically ranging from about 50-60kg CO2eq/tonne at the asphalt plant gate. A report3 by the US National Asphalt Pavement Association has shown that, among raw materials, bitumen is one of the components with the highest footprint, accounting for more than 90% of the raw-material footprint (LCA A1 module).

Moreover, bitumen accounts for more than half of the cradle-to-gate (LCA A1–A3 modules) emissions. Similar conclusions have been reached in Europe when calculations consider Eurobitume’s updated environmental footprint values for bitumen4 5.

Wood residue

LIGNOVA LIGNIN Fibenol, an Estonian cleantech company, is at the forefront of implementing innovative and patented biorefining technology to process residual and low-quality wood into high-value, low-carbon biomaterials. These serve as sustainable alternatives to fossilbased chemicals. One of its flagship products is Lignova lignin, a sustainable product for infrastructure and construction materials and other applications. It exhibits enhanced asphalt performance and significant CO2 reduction for low-carbon and net-zero road solutions.

Lignova hydrolysis lignin has a low CO² footprint certified with an Environmental Product Declaration (EPD). Road trials with Lignova containing asphalt mixtures have been completed in nine countries, in Europe and Japan.

1

Terrel et al. (1980) “Evaluation of Wood Lignin as a Substitute or Extender of Asphalt” (FHWA Report FHWA/RD-80/125)

2

Gaudenzi et al. (2023) “The use of lignin for sustainable asphalt pavements: A Literature review”

3

Shacat et al. (2022) “GHG emissions inventory for asphalt mix production in the United States. Current Industry practices and opportunities to reduce futuure emissions”

4

Eurobitume (2021) “The Eurobitume life-cycle inventory for bitumen. Version 3.1”

5

Eurobitume (2025) “The bitumen Life Cycle Assesment (LCA 4.0)”

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ASPHALT BINDER

Studies on lignin-containing asphalt are also being conducted in the Nordic and Baltic countries, where climatic conditions are challenging. At Tallinn University of Technology in Estonia, research has been ongoing since 2021 on the effect of adding lignin to asphalt binder and on the properties of the final product, such as an asphalt mixture. The aim of the studies is to determine the optimal limit to which asphalt binder can be replaced with lignin while still ensuring that asphalt mixtures comply with local requirements. The research has focused on lignin produced in Estonia by Fibenol and marketed under the brand name Lignova.

In Europe, the penetration-based, asphaltbinder classification system is still used.

However, the tests presented in this article were performed using rheological methods, employing Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) equipment which are widely adopted in North America and globally in academia.

The effect of lignin addition on bitumen properties is illustrated in Figures 1 and 2.

Figure 1 describes the relationship between lignin content and the bitumen PG hightemperature limiting grade. The tests were performed on unaged test samples. The results indicate the temperature at which the ratio of binder complex modulus and phase angle (G*/sinδ) is equal to 1kPa. Figure 2 describes the relationship between lignin content and the bitumen PG low-temperature limiting grade. The tests

Lignin being used by Estonian Transport Administration and the contractor Tariston

were performed after short-term (RTFOT) and long-term (PAV 20h) ageing of the samples. The results in Figure 2 indicate the temperature at which binder stiffness (S) is equal to 300MPa. Testing was conducted after one hour of conditioning.

The findings indicate that at moderate lignin contents, the stiffness of bitumen is not significantly affected at either high or low pavement temperatures. While these results are encouraging, the overarching objective remains to ensure that the final product the asphalt mixture - meets the required performance specifications.

PG high-temperature limiting grade, oC 64

61.4 58.5

Figures 3 and 4 illustrate the effect of Lignova lignin content on a continuously graded wearing course asphalt mixture (AC 16 surf) and on a gap-graded SMA 12 type asphalt mixture. The requirements for the air-void content of wearing course asphalt mixtures in the Nordic and Baltic countries are relatively strict.

Typically, the maximum allowable air-void content of the installed pavement should be below 5%. In Estonia, continuously graded asphalt concrete (AC) mixtures are compacted using a Marshall impact compactor as per EN 12697-30 (2 × 50 blows). SMA-type mixtures

PG low-temperature limiting grade, oC -22

59.7

61.4 59.7

58.5

58 -28 52 -30

-30.6 -34

46 Pen grade 160/220

160/220 15% Lignova

160/220 30% Lignova

Figure 1: The impact of Lignova lignin to the binder PG (performance grading) high-temperature limiting grade at different lignin contents (by weight) 6

-29.2

Pen grade 160/220

160/220 15% Lignova

160/220 30% Lignova

Figure 2: The impact of Lignova lignin to binder PG low-temperature limiting grade at different lignin contents (by weight)

Izaks et al. (2025) “Performance evaluation of stone mastic asphalt (SMA) containing reclaimed asphalt (RA) and biopolymer lignin”

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ROAD SURFACE TECHNOLOGY 2025

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ASPHALT BINDER

AC 16 surf Air-voids content, %

SMA 12 Air-voids content, %

6%

6% 4.1%

4.3%

4%

4% 2.3%

2%

2%

0%

0% Reference 70/100 B=5.2%

70/100 20% Lignova B=4.2%

160/220 30% Lignova B=3.6%

Figure 3: The impact of Lignova lignin to continuously graded AC 16 surf asphalt mix air-voids content; B indicates the amount of added virgin binder

are compacted using a gyratory compactor as per EN 12697-31 (120 gyrations).

In addition to the results indicated above, research carried out at the Riga University of Technology in Latvia has recently led to a published peer-reviewed journal article which focused on evaluating the impact of the amount and type of lignin to SMA asphalt properties6. The results indicated that in SMA-type asphalt mixtures, up to 30% of asphalt binder could be substituted with hydrolysis lignin without negative impacts on mixture properties.

Previous and current research suggest that binder can be partially successfully substituted with lignin up to a certain limit, thereby reducing the share of fossilbased binder in asphalt mixtures. However, attention must be paid to the fact that at higher lignin contents, issues may arise with mixture air voids. This indicates that lignincontaining mixtures require prior validation under laboratory conditions before field implementation.

CONCLUSIONS The influence of lignin on the properties of binder is relatively small. However, the substitution of asphalt binder with lignin has a more pronounced effect on the properties of asphalt mixtures, particularly at higher lignin contents. In asphalt-mixture design, achieving the required air-void content is one of the primary performance criteria.

At Lignova lignin contents of 15-20%, the properties of the asphalt mixture can generally be expected to remain unchanged.

At higher lignin contents (above 15-20%), there is a risk that the mixture will not meet

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ROAD SURFACE TECHNOLOGY 2025

160/220 30% Lignova B=4.3%

Reference 70/100 B=6.2%

Figure 4: The impact of Lignova lignin to gap graded SMA 11 asphalt mix air-voids content; B indicates the amount of added virgin binder

the required air-void content. This indicates that for a given mix design, the effect of lignin must first be evaluated under laboratory conditions.

Higher replacement levels are achievable in SMA-type mixtures. Lignin has a smaller impact on the properties of SMA mixtures compared to continuously graded asphalt mixtures. Results indicate that up to 30% replacement could be considered feasible.

There’s general correlation that higher lignin replacements are available in asphalt mixtures where the initial binder content is also higher.

The evaluations that have been implemented on the specific road trials and projects so far confirm that Lignova lignincontaining asphalt mixtures are technically viable.

CHALLENGES Lignin is susceptible to thermal degradation at temperatures above 180°C and combustion.

Thus, WMA/LTA technologies (warm mix asphalt/lower temperature asphalt) should be considered if production temperatures exceed this threshold. This is especially important if RAP (recycled asphalt paving) is used and virgin aggregates are heated to more than 200°C. Wet mixing and dry mixing? The lignin special gravity is higher compared to asphalt binder. Wet mixing prior to asphalt-mix production could be problematic due to lignin-binder phase separation during longterm storage.

In its unmodified form, lignin is not capable of fully replacing asphalt binder.

Future research, therefore, could focus on how to increase lignin-binder compatibility.

In addition, current asphalt-plant feeders are not always designed to allow for the low bulkdensity of lignin-type additives.

Future cooperation between asphalt-plant producers and asphalt producers is needed to simplify the transition to lignin asphalt mixtures. Nonetheless, industry-driven innovation and close collaboration with stakeholders is already paving the way for a more resilient road infrastructure. ■ Fibenol https://fibenol.com Kait Kaarel Puss is Lignova application development manager with Fibenol and holds a doctorate from the University of Tartu where he studied the characteristics of the lignin obtained from wood. Karli Kontson is project manager for the road engineering and geodesy research group in the department of civil engineering at Tallinn University of Technology. For five years he was chief specialist within the road development and investments department at the Estonian Road Administration.

Fibenol is a 100% private equity-based company based in Estonia. It focuses on creating sustainable biomaterials that, apart from patented Lignova, include wood sugars and specialty celluloses. Fibenol is a spin-off of Graanul Invest Group that operates in bioenergy and renewable energy production.

Graanul Invest is a private company that has more than 17 years of experience in wood processing. It is one of the biggest pellet producers in Europe and one of the biggest independent renewable-energy producers in the Baltic Sea region. www.globalhighways.com

POLYMERIC ADDITIVE

An asphalt mix based upon a PGXpand PMB

CARBON REDUCTION WITH PGXPAND Sripath’s polymeric additive can help reduce the carbon footprint associated with the production of polymer modified bitumen (PMB).

Deepak Madan and Jill McConaghie explain. he call for net-zero emissions is reverberating globally in response to an increasing desire for a circular economy.

According to the United Nations, 107 countries, accounting for 82% of greenhouse gas (GHG) emissions, have adopted net-zero goals¹. However, it appears that efforts to reduce GHG emissions are failing to meet reduction targets set for 2050.

As a result, industries and jurisdictions around the globe are embracing innovative processes and technologies to help meet their sustainability goals. Notably, the asphalt-paving industry is taking steps to meet new GHG emissions standards and to reduce its overall energy consumption.

For example, the UK has adopted a robust set of net-zero goals to reduce carbon emissions during production and paving of asphalt mixes and is evaluating various additives and technologies to reduce GHG emissions². It is well recognised that the majority of energy attributed to asphalt-mix production comes from heating aggregates to the desired production and paving temperatures³.

As a producer of asphalt additives, Sripath Technologies provides a range of

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sustainable products that help contractors adopt and implement new technologies.

These can help reduce carbon emissions by eliminating excess material use, lowering energy consumption and reducing GHG emissions from ‘cradle to gate’. The term refers to a lifecycle-assessment approach that evaluates the environmental impact of a product from its initial extraction of raw materials (‘cradle’) up to the point where it leaves the manufacturing facility (‘gate’). This assessment includes the energy and resources consumed during production which is crucial for understanding a product’s overall sustainability before it reaches the consumer.

PMB AND SUSTAINABILITY Polymer modified bitumen binders are routinely used in road-construction projects due to their enhanced roadway performance.

Incorporating polymers into the binder can significantly improve resistance to rutting, cracking and ageing, thus helping to extend pavement life and reducing the need for maintenance. This durability makes PMB especially valuable in regions facing extreme weather or high traffic volumes.

While these benefits clearly bolster cost savings, PMB use can also help contractors pursue their sustainability goals. The longer

service life of PMB-based roadways can mean fewer repairs and resurfacing cycles.

This can directly reduce energy use, rawmaterial consumption and greenhouse gas emissions over the lifespan of the road. Additionally, PMB-based mixes are also compatible with reclaimed asphalt pavement (RAP), helping reduce the carbon footprint. Furthermore, most polymers used for PMB production are considered to be environmentally stable and inert once blended into bitumen. They typically do not leach harmful substances under normal road conditions.

However, PMBs formulated with styrenebutadiene-styrene (SBS) do pose certain environmental challenges. The production of SBS - a synthetic polymer derived from petroleum - involves energy-intensive processes, resulting in a relatively high value of global warming potential (GWP). Also, SBS-based PMBs typically require highenergy shear mixing, longer mixing times and higher mixing temperatures during production. All this results in higher energy consumption and an increased carbon footprint.

Innovative additives, such as Sripath’s PGXpand, are designed to deliver the desired performance characteristics of a PMB ROAD SURFACE TECHNOLOGY 2025

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POLYMERIC ADDITIVE

PGXpand®

Key features in PMB l Low shear mixing process l Short mixing times l High storage stability l Very compatible with elastomers and crumb rubber

binder while mitigating the negative impact on sustainability exhibited by traditional polymers.

BITUMEN-FRIENDLY ADDITIVE Sripath’s PGXpand was formulated to optimise PMB production while delivering the desired performance, cost reductions and sustainability results. As seen in figure 1, PGXpand boosts the high-temperature performance, paving grade and softening point of PMB mixes without impacting low-temperature properties. The result is outstanding rutting resistance and excellent fatigue properties for longer lasting road surfaces.

PGXpand-based PMBs are used for a range of paving applications including hot mix, hybrid PMBs, hot-spray seal, high-stiffness asphalt mixes and repair and maintenance jobs. As seen in the PGXpand Environmental Product Declaration⁴ (EPD), PGXpand has a global warming potential (GWP) of 2.95kgCO₂eq per kg of PGXpand. As a comparison, the GWP value for commercially available SBS polymers is reportedly around 4.5kgCO₂eq per kg of polymer.

As seen in figure 2, compared to traditional elastomeric and plastomeric polymers, PGXpand has been designed to easily blend into bitumen using low shear mixing equipment, shorter mixing times and lower mixing temperatures. This results in less energy consumed to create a PGXpandbased PMB. In addition, asphalt mixes based on a PGXpand PMB can be paved at lower temperatures.

PGXpand is a highly dosage-efficient additive when compared to traditional polymers. Also, when using PGXpand, there is no need for a crosslinking additive or a warm-mix additive. The reduction or elimination of raw material helps further reduce the carbon footprint.

PGXPAND AND GLOBAL WARMING As part of this study, a comprehensive model was developed to study the impact of varying PGXpand content versus SBS polymer content on the global warming potential. Table 1 lists the key parameters and

Environmental product declaration A bitumen-friendly polymericadditive for paving & roofing applications

Helps reduce PMB cost l Lower energy consumed to create PMB l Lower temperature / energy to pave l Highly dosage efficient compared to SBS

Global warming potential GWP = 2.947

Figure 1: PGXpand: a bitumen-friendly polymeric additive

Traditional

PGXpand®

bitumen-friendly polymeric additive

plastomeric polymers

Fatigue: Good Rutting: Acceptable Elastic recovery: Good

Fatigue: Good Rutting: Excellent Elastic recovery: Poor

Fatigue: Poor Rutting: Good Elastic recovery: Poor

Mixer: High shear Mixing time: Long

Mixer: Low shear Mixing time: Short

Mixer: Medium Mixing time: Medium

Mix temperature: High Paving temperature: High

Mix temperature: Low Paving temperature: Low

Mix temperature: High Paving temperature: High

Crosslink additive: Needed Warm mix additive: Needed

Crosslink additive: Not needed Warm mix additive: Not needed

Crosslink additive: Not needed Warm mix additive: Needed

Figure 2: PGXpand differs from traditional elastomeric and plastomeric polymers

assumptions adopted for this study.

Because PGXpand is a highly dosageefficient additive, typically only 3% of PGXpand is needed to deliver the same performance as a PMB with 6% SBS. Similarly, only 2% of PGXpand is needed to deliver the performance of a PMB with 4% SBS. In figure 3, GWP values are reported as kgCO₂eq per tonne of PMB. A PMB with 3% PGXpand had a significantly lower GWP value - only 93kgCO₂eq per tonne - compared to a GWP value of 41kgCO₂eq per tonne for a PMB with 6% SBS. Furthermore, a PMB with 2% PGXpand has a GWP value of 64kgCO₂eq per tonne.

Figure 4 depicts the percentage reduction in GWP for various PMBs compared to the control PMB produced with 6% SBS. Increasing PGXpand content while lowering SBS results in higher values of percentage

Content

GWP, kgCO2eq Mixer type per kg polymer

Mix time

Crosslinker

SBS

0-6%

4.5

High kw

Long

Yes

Hybrid

Both

Based on %

High kw

Long

Yes

PGXpand

0-3%

2.95

Low kw

Short

No

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ROAD SURFACE TECHNOLOGY 2025

Traditional

elastomeric polymers

Polymer

Table 1: Key parameters and assumptions

Excellent performance Boosts high temperature performance, paving grade, and softening point l No impact on low temperature properties l Outstanding rutting resistance l Excellent fatigue properties l Low viscosity mixes l Improves workability, easier to compact l Excellent weathering performance l

reduction in GWP. PMB “A”, with 4.5% SBS and 1.25% PGXpand, shows a percentage GWP reduction of 19%. Meanwhile, PMB “B”, with 3.5% SBS + 1.25% PGXpand, shows a percentage GWP reduction of 30%.

Thus, replacing SBS with PGXpand can reduce the overall carbon emissions while delivering comparable mix-level performance.

PMB “C” with 3% PGXpand shows a percentage GWP reduction of 77%. PMB “D” with 2% PGXpand shows a percentage GWP reduction of 85%. This suggests that while PGXpand-based PMBs can deliver performance comparable to the control PMB, they are a much more sustainable alternative to SBS when considering lifecycle emissions.

As part of this study, the percentage reduction in GWP was also evaluated for PMBs produced using a crosslinking additive. Figure 5 illustrates that even when a crosslinking additive is used during the production of the PMB, replacing SBS with PGXpand improves the carbon savings.

Compared to the control, with 4% SBS, both the PMB with PGXpand addition showed a higher value of percentage GWP reduction. The data suggests that reducing www.globalhighways.com

POLYMERIC ADDITIVE

500 400

Global warming potential (GWP), kg CO2 eq/ton 419

300

% Reduction in global warming potential (GWP) 100% 80%

375

60%

329

200

20%

93

0 SBS Polymer PGXpand

64 PGXpand

5.0%

4.0%

-

-

-

-

-

3.0%

2.0%

% Reduction in global warming potential (GWP)

18%

10%

SBS PGXpand

PMB “C”

PMB “D”

6.0%

4.5%

3.5%

-

-

-

1.25%

1.25%

3.0%

2.0%

Figure 4. Impact of PGXpand on percent reduction of the global warming potential

80 PG grade

25%

PMB “B”

PGXpand

89

60

20%

PMB “A”

100

40% 30%

Control SBS

6.0%

40

30%

19%

0%

0%

Figure 3. Impact of varying SBS polymer and PGXpand content on GWP

0%

85%

40%

100

SBS

77%

54

True PG low grade True PG high grade 70

67

68

54

20 0

0%

-20

Crosslinking additive used for PMBs with SBS polymer

-40

-35

-35

-34

-33

-35

-34

-34

-34

Binder

Control

PMB

PMB

Control

PMB

PMB

PMB

PMB

-

1.5%

2.5%

-

1.5%

2.5%

1.5%

2.5%

4.0%

3.0%

3.5%

PGXpand

-

1.25%

1.25%

Ageing

No ageing

12-hr Oven ageing @ 135 C o

Figure 5. Impact of PGXpand on percent reduction of the GWP potential of crosslinked PMBs

Figure 6: Ageing performance of PGXpand in a polymer modified bitumen

SBS while increasing PGXpand, even in the presence of a crosslinking additive, can lead to a reduction in carbon emissions while delivering the desired mix-level properties.

PGXpand offers a more energy-efficient approach to producing PMB, helping producers lower energy consumption and production costs. The additive is engineered to reduce greenhouse gas emissions throughout its lifecycle including production, transportation and during use in the intended application. PGXpand also enables paving and compaction at reduced temperatures, leading to additional savings in fuel and operational costs.

Figure 6 shows that PGXpand-based PMBs maintain the true PG low grade even after various ageing regimens, demonstrating these PMBs have good resistance to ageing and can deliver longterm surface durability.

temperature of 130oC compared to 160oC for a control mix. The PGXpand-based PMB was easy to produce, had superior mix properties and workability and delivered excellent rutting resistance.

Sripath has a strong track record of committing to sustainability. The company has embraced transparency by making all its Environmental Product Declarations easily accessible online⁴. The EPDs are issued by the Environmental Footprint Institute, Madrid, Spain.

With a GWP of 2.95kg of CO₂eq per kg of PGXpand, the bitumen-friendly polymeric additive exhibits lower greenhouse gas emissions than traditional polymers used in PMB production. ■

CONCLUSION As an example of a real-world case (see main image of article), a road surface was paved using a PMB binder dosed with 1.5% PGXpand. A 30mm wear layer was paved on a one-kilometre four-lane section of the heavily used highway. Paving was done at a www.globalhighways.com

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Sripath https://sripath.com Sripath Technologies is a global company that develops, manufactures and markets bitumen and asphalt additives, all with an emphasis on sustainability. Deepak Madan, chief operating officer of Sripath, received his PhD from Rensselaer Polytechnic Institute in the US city of Troy in New York state.

1-wk ageing @ 90oC

Jill McConaghie, business development specialist at Sripath, received her BA in English literature from Richard Stockton College in the US state of New Jersey.

The authors wish to acknowledge the sustainability modelling work and report

by Paloma Garcia-Poggio and Luis Vega of Geovitia, based in Ellesmere Port, England.

References: 1) “For a livable climate: Net-zero commitments must be backed by credible action.” United Nations. https://www.un.org/en/climatechange/ net-zero-coalition. Accessed July 23, 2025.

2) “Net-zero highways: our zero-carbon roadmap for concrete, steel and asphalt.” National Highways. https://nationalhighways.co.uk/ media/2prpkf4e/net-zero-roadmap-forconcrete-steel-and-asphalt.pdf. Accessed July 23, 2025.

3) “A Review of Sustainability in Hot Asphalt Production: Greenhouse Gas Emissions and Energy Consumption.” Applied Sciences 2024, 14 (22). https://www.mdpi.com/20763417/14/22/10246. Accessed July 23, 2025.

4) “Focus on Sustainability.” Sripath Technologies.” https://sripath.com/sustainability/. Accessed July 23, 2025.

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ASPHALT COMPACTION

Two infrared (IR) temperature sensors (front and rear) mounted on the roller measures the surface temperature of the asphalt in the direction of travel

SEISMIC ASPHALT: RESONANCE-BASED COMPACTION The Seismic Asphalt system from Dynapac automatically detects the optimum asphalt-compaction frequency and continuously adjusts it accordingly.

This means increased machine efficiency, lower cost of ownership from fuel savings and less wear and tear on the roller. Andreas Persson explains. he Seismic system of compaction was originally developed by Dynapac for soil compaction and has been in use since 2019.

Its performance for soil compaction is well documented. The system uses the principle of resonance and offers several technical advantages. These include lower energy and fuel consumption, reduction of double jumping, lower noise levels and decreased mechanical wear.

Last year, Dynapac launched its first asphalt roller equipped with the Seismic system, Seismic Asphalt. While the underlying principle remains the same, Seismic Asphalt has been carefully adapted to meet the distinct challenges of asphalt compaction.

T

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TEMPERATURE EFFECTS Although asphalt mixtures typically consist of 90-95% mineral aggregates, there is one key aspect that differs from soil: the binder in asphalt exhibits strong thermo-plastic characteristics. This affects the material’s stiffness during compaction, particularly as the mix cools. This is precisely what distinguishes Seismic Asphalt from Dynapac’s Seismic Soil system - the asphalt system must continuously account for thermal variations to maintain optimal performance.

When asphalt is freshly laid and hot, it is relatively easy to compact. As it cools, the binder stiffens rapidly, making the material more resistant to compaction. Figure 1 illustrates that, as the temperature drops, the compaction effort (amplitude) must increase

to maintain effective densification.

Traditional solutions to this problem involve mechanically adjusting the drum amplitude using complex internal mechanisms. While technically feasible, these systems are sensitive, costly and energyintensive. Dynapac’s approach with Seismic offers an alternative. By modifying the vibration frequency to match the resonance characteristics of the drum-material system, amplitude can be increased naturally, without mechanical intervention.

THE PRINCIPLE OF SEISMIC Seismic is based on the resonance phenomenon, where a vibrating system reaches its maximum amplitude when operating at its natural frequency. For www.globalhighways.com

ASPHALT COMPACTION

End of compaction

Amplitude

Compaction effort

Favourable compaction temperature Start of compaction

Resonance frequency 40

60

80

100 120 140 160 180 200

o

C

Frequency

Mix temperature in oC Figure 1: Compaction effort as a function of the mix temperature: to achieve the desired density, a cooler mix requires a higher compaction effort (higher amplitude) compared to a warmer mix

Figure 2: General resonance curve: the vibration amplitude is amplified when the compaction frequency correlates to the resonance frequency (natural frequency) of the drum-material system

End of compaction

Amplitude

Amplitude

Favourable compaction temperature Start of compaction

Resonance frequency

Frequency Figure 3: Resonance curve from an asphalt application

every combination of drum mass and material stiffness, a resonance curve can be established (see Figure 2). It is important to note that the amplitude values typically quoted in technical specifications refer to the nominal amplitude - measured when the drum is suspended in air. Once the drum contacts the ground, the actual amplitude is influenced by the dynamic interaction between drum and material.

Figure 3 shows a typical resonance curve for asphalt. While the amplitude peak is less pronounced than in soil, it is still significant.

Operating below the resonance frequency results in a sharp drop in amplitude and compaction performance. Operating above the resonance frequency yields a more gradual decline in amplitude. This behaviour www.globalhighways.com

Frequency (Hz) Figure 4: Combined temperature and stiffness/resonance curve for an asphalt application: how close the machine shall operate with respect to the resonance frequency is based on the mix temperature, giving exactly the right “amplitude boost” required to maintain an efficient compaction process even at lower mix temperatures

is key to understanding how Seismic can be used to optimise compaction.

FREQUENCY ADJUSTMENT In soil applications, it has been demonstrated that adjusting the vibration frequency to approach the resonance frequency increases the actual drum amplitude - without requiring mechanical changes. This is a technically elegant solution that avoids the complexity and energy demands of mechanical amplitude adjustment systems.

In asphalt applications, the need for increased amplitude as the mix cools can be addressed by adjusting the vibration frequency to move closer to the resonance peak. Figure 4 combines temperature and stiffness data to show how the system

determines the optimal operating frequency.

When the mix is hot, the roller operates above the resonance frequency, avoiding unnecessary amplitude boosts. As the mix cools, the system lowers the vibration frequency, increasing amplitude naturally to maintain compaction efficiency.

SYSTEM ARCHITECTURE The Seismic Asphalt system integrates several components to achieve this adaptive behaviour. Two infrared (IR) temperature sensors (front and rear) mounted on the roller measure the surface temperature of the asphalt in the direction of travel.

Simultaneously, a compaction meter calculates the resonance frequency of the drum-asphalt system.

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ASPHALT COMPACTION

LEFT: In asphalt applications, the need for increased amplitude as the mix cools can be addressed by adjusting the vibration frequency to move closer to the resonance peak

adapts dynamically to changing material conditions. This enables effective compaction even as the mix cools, without the need for complex mechanical systems.

For engineers and practitioners in the field, Seismic offers a compelling example of how fundamental physical principles such as resonance - can be applied to solve practical problems in road construction.

The system’s ability to maintain performance while reducing energy consumption and mechanical complexity makes it a noteworthy development in compaction technology. ■ https://dynapac.com/en/seismic

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ROAD SURFACE TECHNOLOGY 2025

front drum. This results in asymmetric compaction behaviour, as the rear drum operates without active adjustment. In contrast, the Seismic system applies frequency-based control to both front and rear drums, maintaining maximum compaction performance of the machine.

CONCLUSION The Seismic Asphalt system represents a technically sound approach to the challenges of asphalt compaction. By integrating realtime temperature sensing with resonancebased frequency adjustment, the system

Andreas Persson is the inventor of Dynapac’s patented Seismic system and has 18 years of experience in the compaction industry. He is lead engineer in application and vehicle dynamics at Dynapac where he focuses on applying physical principles to improve machine performance and efficiency.

SMA 16-48mm: Low amplitude 104.0 Degree of compaction (%)

This data is processed by a logic unit that determines the optimal vibration frequency to achieve the required amplitude boost.

The system performs these calculations and adjustments five times per second, allowing it to respond rapidly to changing conditions such as temperature and material stiffness.

To validate the performance of the Seismic Asphalt system, Dynapac conducted a series of in-house and field trials. These included various asphalt-mix types, such as Stone Mastic Asphalt (SMA), Asphalt Concrete (AC) and Asphalt Base, with different aggregate fractions and layer thicknesses.

More than 360 core samples were extracted and analysed for air-void content to assess compaction quality.

Figure 5 presents results showing the degree of compaction as a function of the number of passes. Each curve represents a different frequency setting, but the same machine (a CC4000 VI) was used throughout. Notably, the Seismic system operated at a significantly lower mean frequency than the fixed-frequency settings, yet achieved equal compaction performance.

This indicates a higher energy efficiency because the system uses resonance to increase amplitude without increasing power consumption.

Long-term field trials, together with contractors, have shown a reduction in fuel consumption of approximately 15% when using a machine equipped with the Seismic system, compared to a non-Seismic machine.

Conventional systems for amplitude adjustment typically rely on mechanical solutions, often implemented only on the

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Seismic Asphalt (Mean freq. 53Hz)

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Upper and lower limit Number of passes

Figure 5: Degree of compaction as a function of the number of passes for a CC4000 VI with different frequency settings operated at High Amplitude (HA)

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MILLING INNOVATION

A FINNISH FINISH FOR FAE

In the heart of Finland, the contractor ESV Urakointi is transforming the way it handles asphalt removal by using advanced FAE technology. An FAE RPL/EX-45 road planer is mounted on a Huddig 1370 backhoe loader. n the heart of Finland, the contractor ESV Urakointi is transforming the way it handles asphalt removal by using advanced FAE technology. An FAE RPL/EX45 road planer is mounted on a Huddig 1370 backhoe loader.

The RPL/EX is for excavators from 8-14 tonnes and is capable of milling to a depth of 13.5cm. It is normally used to prepare roads for resurfacing before laying a new layer of asphalt or cement, or to simplify excavation operations, explained Marko Turunen, who has first-hand experience working on the combination of FAE and Huddig technologies. The RPL/EX road planer’s cut is clean and precise and the residual milled material can be reused as filler before the new asphalt layer is paved.

“We first started using the FAE RPL/EX45 in spring 2024,” recalled Turunen. “Since then, this machine has become an essential part of our work and has always proven its versatility and efficiency, starting with simplicity of setup. The machine comes with clear instructions showing where to connect the oil pressure lines as well as the return and drain lines.”

The only modification required was upgrading hydraulic lines to the correct length. To ensure a perfect connection of the hydraulic lines Turunen’s team sought advice from the Huddig dealer, which promptly answered all questions from ESV Urakointi.

From the operator’s perspective, the FAE RPL/EX-45 stands out for its exceptional functionality. Turunen described the experience as “revolutionary”, saying that he “can’t think of a better way to remove asphalt than using this FAE”.

From a site-safety perspective, no accidents related to its use have been reported.

“Occasionally, some small debris may be expelled which stops after travelling about one or two metres. This doesn’t compromise safety on the construction site at all,” said Turunen. In fact, in addition to performance, the machine is designed with safety in mind, partly due to its frequent use in

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The FAE RPL/EX-45 road planer exemplifies innovation that simplifies work (image courtesy FAE)

urban settings, near houses, sidewalks and footpaths.

“After several months of use, the machine has not yet required specific maintenance, other than greasing every now and then,” he said. “The picks, which are 42 round bit picks over a 60cm-diameter rotor, have not yet worn out and are still working very efficiently.”

ESV Urakointi rented the FAE RPL/EX-45 model from earthworks and infrastructure contractor Varpaisjärven Maansiirto, which purchased it from the dealer FAE Tapio Pirttinen. Tapio Pirttinen was founded in western Finland in 1977 and specialises in the sale of agricultural and road-maintenance equipment. It is a small family-run business, now in its second generation and headed by Jukka Pirttinen. “We gradually moved from manufacturing to importing in 2001 and now imports account for 95% of our business. We have been working with FAE for many years and are very satisfied with the collaboration,” said Pirttinen.

The story of Marko Turunen and ESV Urakointi illustrates how modern technology can revolutionise the way work is done in road construction and maintenance. The FAE RPL/EX-45 road planer exemplifies innovation that simplifies work, increases efficiency and improves the operator experience. ■ FAE www.fae-group.com ROAD SURFACE TECHNOLOGY 2025

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ASIMOB and Renault Group have collaborated in Spain’s DIVEC project to analyse the effectiveness of road markings - especially for lane delineation in the fast-approaching future of autonomous driving, explain the authors from ASIMOB*. n 2019, the European Union (EU) approved the New Safety Regulation 2019/2144. This establishes new general vehiclesafety requirements, including the protection of occupants and vulnerable road users. The regulation requires automotive manufacturers to implement advanced driver-assistance systems (ADAS) such as lane-keeping assistance systems (LKAS).

However, the increase in ‘run-offroad’ accidents, resulting in fatalities in recent years¹, appears to cast doubt on the effectiveness of lane-keeping systems in vehicles.

Meanwhile, the effectiveness of ADAS depends on two factors: the quality of the system in the vehicle and the proper design and maintenance of the road. While automotive manufacturers make great efforts to optimise their systems, the heterogeneity of roadways presents a major challenge for ADAS. In Spain, the DIVEC project - an acronym from the Spanish words for Smart Electric and Connected Vehicle Design - has addressed this issue by using ASIMOB’s Autonomous Road Inspector and the lanekeeping system of Renault’s Megane E-tech 100% electric vehicle.

Analysis of the visual quality of the road markings, especially lane-marking lines, is key to understanding the difficulties faced by human drivers and ADAS when attempting to follow lanes. The European strategy for the adoption of autonomous vehicles, based on the Vision Zero objective and the regulation prior to implementation, establishes road authorities as the ultimate guarantors of infrastructure suitability². Authorities must continuously evaluate roadway conditions.

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EUROPEAN STANDARD EN 1436 The European Standard for Road Markings, EN 1436³, updated in 2018 and published

by BSI as BS EN 1436:2018, specifies the performance that white and yellow road markings should provide for road users.

To indicate the visibility of a road marking under daytime conditions, the luminance coefficient in diffuse illumination (Qd, measured in mcd*m2*lux-1) is used.

Depending on the class of the road marking, luminance must reach certain values. The required minimum value of Qd also depends on the type of pavement (bituminous or concrete) on which the lines are painted because the daytime visibility of road signage depends on the contrast ratio between the road signage and the surrounding pavement.

The retroreflected luminance coefficient RL is used for measurement of retroreflection under vehicle-headlight illumination - the conditions under which a driver perceives road markings when driving at night on an interurban road without public lighting.

This standard leaves the selection of the quality level open to the criteria established by each country. Several classes are used in different countries, with their choice varying, depending on the road level.

SHAPES AND DESIGNS In DIVEC, the Spanish Road Standard 8.2IC for Road Markings4 was used to analyse the limitations of the current standards.

The standard defines different white road markings (that are generally used), yellow markings (that note stopping and parking areas) and blue markings (that define parking areas).

© Nikita Zabellevich | Dreamstime.com

MARKINGS IN THE AGE OF ADAS

In the case of lane lines, the standard defines the length and width of the lines and the separation between lines in the case of broken lines. This depends on the speed assigned to the road, with a distinction between ordinary overtaking zones, reversible lane zones, entry and exit zones on highways, bifurcation warning, separation of special lanes, continuous line warning or danger.

Similarly, continuous lines are defined by their width, distinguishing between those defined for entry and exit distinction, edge of the roadway and the contour of an impassable island.

Finally, combinations of continuous and broken lines that are possible are also defined.

Beyond the definition of individual lines and the combinations of types of lines, some areas such as highway entrances and exits are explained visually to clearly show the necessary combination of lines.

Even so, some parameters remain undefined in these schemes. For example, the distance between the start point of the deceleration lane and the point where the broken line of this lane begins to be painted is not defined. This makes its application very diverse.

NEW REQUIREMENTS The incorporation of ADAS - particularly the implementation of the LKAS for lane-line tracking - exposed the limitations of the regulatory framework for road markings. The standard is restricted to ideal scenarios and focuses on measuring the retroreflectivity of the line, when there is one. Unfortunately, reality is much more complex.

The foundational and widely recognised www.globalhighways.com

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publication in this field is a 2013 report

by EuroRAP (European Road Assessment Programme) and EuroNCAP (European New Car Assessment Programme). It is titled Roads that Cars Can Read⁵ and was updated in 2018. During consultation, vehicle manufacturers identified and prioritised factors according to their impact with roadmarking quality being identified as one of the most important. The impact factors were divided as follows: High-impact factors: • Condition of the road surface, e.g., wet or icy • Worn road markings • Multiple and confusing road markings • Old or no-longer valid road markings, not completely removed Medium-impact factors: • Road slope • Curvature, boundaries between several lanes Low-impact factors: • Lane width, e.g., too narrow or too wide • Visibility, e.g., fog Although these are the results featured in the Roads that Cars Can Read report, the quality standard for road markings is determined by the European Road Federation and aligns with specific levels set by the European Standard EN 1436. As with other similar European standards, different performance levels can be chosen in this regulation.

Aside from these consultative processes, several field tests have been conducted on the effects of road-marking characteristics on machine-vision systems. In general, field tests of machine-vision systems indicate that the most important factor for recognising road markings in daylight is the luminancecontrast ratio between the marking and the pavement. Meanwhile, at night it is retroreflection. Therefore, it can be concluded that the same variables influence machinevision systems as they do human vision.

In the US, research is underway as part of the NCHRP programme of the Transportation Research Board, such as project 20-102, which covers a series of initiatives on connected and autonomous vehicles. Task 6 is dedicated to Road Markings for Machine Vision and aims to gather information on the performance characteristics of road markings that affect the ability of machine-vision systems to recognise them. www.globalhighways.com

Suitability of lane lines for LKAS

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Some preliminary conclusions about the effects of road markings on machine vision are: • Edge lines and lane markings perform equally well • Public lighting has minimal impact on night performance • Detecting markings during the day is more difficult than at night, especially on wet days, due to glare from reflection • Speed (up to about 104km/h) has minimal impact • For dry daytime conditions, a level above 100mcd∙m2∙lux-1 seems appropriate • Tests continue in wet conditions and compare line widths of 100mm and 150mm AUTOMOTIVE INDUSTRY CONSIDERATIONS According to several recent surveys⁶, automobile manufacturers prefer highly visible and unequivocal road markings on both sides of the lane. They considered visibility important not only under good conditions, but also in shaded areas when the sun was at a low angle and during rainfall.

Regarding edge lines, some clear cases of limitations have been detected in road designs conceived for human driving: the arrangement of gaps without longitudinal road markings at highway entrances and exits and at lane additions or reductions. These gaps without road markings force drivers of vehicles with current semi-automated systems to “take over” the driving function.

This clearly limits automated driving, even in highway or expressway environments where there should be no such problems. It

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is worth noting that this issue has also been observed and studied on Spanish roads in a study conducted at the Polytechnic University of Valencia (Alfredo García, 2017).

The third and, to date, last update of the EuroRAP report Roads that Cars Can Read, published in 2018, subtitled Addressing the Transition to Automated Vehicles, goes beyond prescribing certain levels of retroreflection for road markings. The report stresses that there will be higher accident risk in cases where road maintenance and upkeep are inadequate; when road markings are almost erased and cannot be detected by a vehicle’s technology.

SMART ROADS In 2022, a study promoted by PIARC classified smart roads⁷. It explains how each road administration should establish which priorities and thresholds must be considered for each Smart Road Level. One of the two proposed indicators is the Level of Service for Automated Driving (LOSAD): the readiness of a road segment from the perspective of physical infrastructure to support automated driving. To assess the readiness, an analysis of multiple factors must be carried out unfeasible if done manually or visually.

DIGITAL INSPECTIONS ASIMOB’s Autonomous Road Inspector⁸ comprises three parts: • Onboard system of two small and removable devices to capture images and data of the road and its environment.

Being lightweight, the system can be carried even on bicycles. Installation takes 10 minutes and data collection is done while driving at normal speed.

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• Cloud software includes computervision models, post-processing algorithms and data analysis.

ASIMOB’s AI models are designed to meet the needs of road-asset inspection.

• Web application for results visualisation and downloading reports and video/image evidence. Clients receive up-to-date information for situational awareness and decisionmaking. Integrating result data into external platforms (ArcGIS, QGIS, etc.) is straightforward.

The solution can be used in urban and interurban settings. However, not all public administrations face the same problems and sometimes assign responsibilities for different road elements under various contracts. Therefore, the ASIMOB service is offered in a modular way: • Vertical traffic-sign control • Monitoring temporary signage in construction zones • Early detection of pavement damage • Monitoring road markings • Evaluation of homogeneous visibility during night (lighting) • Control of vertical signs for safety and tax purposes • Collection of road geometrical data All inspection services comply with GDPR requirements, privacy regulations and AI Act requirements. The solution is applied for both asset management and road-safety inspections.

Vertical signage Road markings

• Heat map of road network showing visibility level of lane markings • Map displaying location of horizontal traffic signs • Direct access to video from the latest inspection of each stretch of road • Files to download the information, including data such as the sign code, location (UTM coordinates, kilometre point, road name, direction), cropped image of the sign, video, as well as quality parameters of the marking • Virtual aerial view of the road THE DIVEC PROJECT The DIVEC project is under Spain’s Strategic Project for Economic Recovery and Transformation for the Electric and Connected Vehicle. It is managed by the Ministry of Transport and Sustainable Mobility to address the challenge of lane-keeping assistance systems and is a collaboration between Renault Group and ASIMOB. The analysis compares the results obtained by the ASIMOB Autonomous Road Inspector with those obtained by the lane-guidance system used in Renault’s new Megane E-tech 100% electric vehicles.

Within the project framework, all the variables recorded by the vehicle for lane identification were identified.

Smart roads Work zones

Assets management Road safety evaluation

Autonomous road inspector Measuring on picture

The Autonomous Road Inspector enables visual data collection of road markings as well as the detection of line visibility in different conditions (day, night, rain). For each inspection, the results provided by the solution are:

Protection barriers Pavement status

Forensic analysis of accidents Autonomous vehicles adoption check

Events from FCD Autonomous Road Inspector scope

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These variables are limited not only to the location of the right- and left-lane delimitation lines but also include other elements that can provide information about the end of the lane or the end of the platform. The aim is to keep the vehicle on the platform when the lane-delimitation line is not detected. Some examples of these elements are curbs, end of shoulder and drainage channels.

When driving with the LKAS, the vehicle continuously collects the information and controls the steering wheel to make the necessary adjustments and follow the lane. In the evaluation process of the lane-guidance system carried out within the DIVEC project, the data generated by the vehicles has been extracted in order to be compared with the quality-analysis results of road markings obtained using the Autonomous Road Inspector.

The Road Inspector was installed in the same vehicle that also recorded the laneline data. In this way, the vehicle data and the data obtained by the Inspector could be compared. The results made it possible to detect situations that hinder lane detection by the vehicle’s LKAS. The different detected cases, classified according to the factor causing the incidents, are divided into four categories: • Lane detections with visualised lane line, no incident • Lane detections with incident: no visualised lane line, due to the presence of other reference elements • Undetected lanes with visualised lane line • Undetected lanes without visualised lane line The detections carried out by the Autonomous Road Inspector showed different levels of lane-line visibility. In the map image, the following can be observed: • (green): lanes where both left and right lines are correctly visualised • (yellow): lanes where at least one of the two lines is slightly degraded, though still detectable • (orange): lanes where at least one of the lines is almost imperceptible in some section • (red): line not perceptible at all The map shows multiple sections of the route where the lines are degraded or very degraded: www.globalhighways.com

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The authors are Ibon Arechalde, Estibaliz Barañano and Amaia Aretxalde.

Arechalde trained as a telecommunications engineer and music composer in the 1990s.

At ASIMOB, he is focused on the digital transformation of roads, helping public administrations with their maintenance and evaluation of road safety through artificial intelligence, computer vision, data analytics and sensors.

Road sections coloured according to results

These sections coincided with places where the vehicle lost the lane reference or relied on the detection of other elements to consider the lane reference. The analysis of the data obtained by the Autonomous Road Inspector allows for identifying the causes of loss-of-lane reference, which may be due to various reasons: • Lane lines degraded by wear • Dirty lane lines • Lane lines with low contrast • Lane lines interrupted by maintenance work (milling, incorrect painting) • Lane lines not painted, but reference from another line • Lane lines not painted, without reference from another line The information obtained by both systems ensures the correlation of the results in more than 92% of cases. The causes of the lane-reference loss cannot be determined by the vehicle but can be detected by the Autonomous Road Inspector. The same tests were repeated at night and in daytime conditions with rain to assess the differences between one set of conditions and the other. During the day, the results can be correlated with values of the luminance coefficient in diffuse illumination. During the night, the results can be correlated with values of the retroreflected luminance coefficient. The results in conditions with rain are equal to, or worse than, the results without rain, in all cases.

CONCLUSIONS The tests carried out within the DIVEC project show a strong correlation between vehicle disengagements and the low-quality www.globalhighways.com

lane markings as measured by the ASIMOB Autonomous Road Inspector.

The causes of the loss-of-lane reference cannot be determined by the vehicle itself.

Nonetheless, they can be detected by the Road Inspector. Various causes can be identified, primarily summarised as either the absence of painted lines or the degradation of existing markings.

The efforts made by automotive manufacturers in developing safer ADAS systems for users should be complemented by the commitment of road authorities to ensure the proper painting of road markings, especially lane lines, which are important for not only ADAS, but for drivers with older vehicles.

Road-marking standards - at European and national levels - have not been updated according to the requirements of ADAS. A review, therefore, should address the need for continuity and visibility characteristics of lane markings under both daytime and nighttime conditions, as well as during rainfall. ■ ASIMOB https://asimob.es/en/asimob DIVEC https://www.sigmacognition.ai/researchprojects/divec *ASIMOB is a technology startup based in Bilbao, Spain, established by entrepreneurs with extensive experience in international technology companies. Their work focuses on improving the safety of current road users and autonomous vehicles of the future, The company’s solutions are aimed at road authorities, maintenance companies and infrastructure data managers.

Barañano holds a MSc in telecommunication engineering and started her career in the telecom sector. After four years she became an entrepreneur with a technology consultancy. In 2004 she joined a multinational engineering company specialising in traffic management and payment systems. She joined ASIMOB in 2019 as general manager, helping define both the commercial and technical aspects of the company.

Aretxalde, a chemical engineer since 2006, worked for 10 years in technical-commercial departments in the renewable-energy sector.

After three years as an entrepreneur, she began her career in the software development sector as a developer and project manager. In 2024, she joined ASIMOB as customer success manager, focusing on identifying and defining new features for the Autonomous Road Inspector.

References 1. Las principales cifras de la siniestralidad vial en España 2023, 2023, DGT 2. Why do road traffic accidents happen?, 2014, Elvik H., Danish Road Traffic Accident Investigation Board 3. European Standard EN 1436-2018, Road marking materials - Road marking performance for road users and test methods, 2018, CENELEC 4. Spanish Road Standard 8.2-IC for Road Markings, 1987, Ministry of Transports of Spain 5. Roads that Cars Can Read, 2018, EuroRAP (European Road Assessment Programme) and EuroNCAP (European New Car Assessment Programme) 6. Características de la infraestructura que pueden favorecer la conducción asistida y automatizada, 2020, Leal Bermejo J.M., CEDEX 7. Smart Road Classification. A PIARC special project, 2021, PIARC 8. Autonomous Road Inspection as first step for Smart Roads, 2024, Arechalde I., Lopez Arantzamendi B., ASIMOB, IRF World Congress, Istanbul

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PUSH-OFF TECHNOLOGY DELIVERS RESULTS The Fliegl push-off technology is ideal where the use of dump trucks is too risky or impossible. It can unload safely, and in a controlled manner, all kinds of bulk materials, including asphalt mixtures.

n the paving sector globally, one of the main issues is sustainability, such as environmental protection and the lowering of CO₂ emissions. This extends down the entire value chain of the paving process, from creating the asphalt mixture at the plant to screeding it right after delivery on a road’s base layer.

But while maintaining a sustainable paving process is important, so too is maintaining the quality of the asphalt.

To enable this, the Asphaltprofi Thermo process from Fliegl offers push-off vehicles that combine perfect insulation with maximum quality and process reliability for asphalt-road construction. The insulating material used for the vehicle body is FlieglIsotherm, a lightweight material applied to the outsides of the body so that it is fully enclosed. This composition allows the Asphaltprofi Thermo to achieve outstanding insulation values. The body, floor, front and rear of the vehicle’s container are fully insulated.

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Meanwhile, the Fliegl push-off technology is ideal where the use of dump trucks is too risky or physically impossible. It can unload safely, and in a controlled manner, not just asphalt but all kinds of bulk material including stone and sand.

It is one thing to deliver asphalt onsite at the right temperature. It is another thing to move it from the vehicle to the paver itself.

The main difference between a thermally insulated tipping body and a push-off vehicle lies in the way the mix is transferred to the paver. There are slight temperature differences in the loaded building material during transport. A cold layer is created on the surface which is placed in the paver first during the tipping process This results in large temperature differences in the asphalt.

With push-off technology, however, the material is pushed into the paver bit by bit.

This means that the material has almost the same temperature composition over the entire duration of the unloading process. It is, therefore, equally tempered. In addition,

The push-off trailer can also be unloaded in buildings with low ceilings, as well as under bridges that have little clearance for a raised tipper truck (image © SREMPUT DOO Ruma, Serbia)

this “bit by bit-dosing” ensures a continuous homogeneity of the mix.

It is also possible to reduce the temperature in the asphalt-building process provided the asphalt is spread using push-off technology without asphalt quality suffering as a result.

Unlike with the tipper method, the differently tempered asphalt layers do not slide into the paver separately, but homogeneously and at a uniformly high temperature during the entire unloading process.

Temperature fluctuations behind the paving screed are effectively minimised which means that the asphalt is easy to compact and can be installed evenly. As a result, a much better paving quality, and thus a longer durability of the asphalt surfaces, is achieved. With the Asphaltprofi Thermo, the asphalt is delivered in an evenly hot and homogenous manner so that it can be laid in optimum consistency.

NIKOLA TESLA AIRPORT A case in point was when a Fliegl Thermo push-off trailer set-up helped optimise asphalt paving at Nikola Tesla Airport in the Serbian capital of Belgrade. The runway was modernised over a distance of almost 7km to further increase the safety and performance of the airport. Precision and efficiency were key for laying down 270,000 tonnes of asphalt on a runway using the ASW Thermo system.

The biggest challenge in large-scale asphalting projects is maintaining a constant temperature of the mix. This is www.globalhighways.com

LOGISTICS-MATERIAL HANDLING

where the Fliegl ASW Thermo comes in, with its thermal insulation that ensures the asphalt remains at the optimum processing temperature throughout the entire transport and paving process. Temperature fluctuations, which can lead to reduced adhesion and cracking, are minimised. As a result, the paving quality is significantly improved and the asphalt pavement lasts longer.

As noted, another highlight of the Fliegl ASW Thermo system is the push-off technology. In contrast to conventional tipper vehicles, it enables controlled and even material discharge. This reduces material losses, prevents compaction problems and ensures precise dosing of the asphalt. In addition, the push-off trailer can also be unloaded in buildings with low ceilings, as well as under bridges that have little clearance for a raised tipper truck.

To recap, the focus is not only on efficiency, but also on safety. There is no risk of the Fliegl ASW Thermo tipping over - an important safety aspect on uneven construction sites. At the same time, the reduced maintenance requirements contribute to a high level of operational- and cost-effectiveness.

Overall, the reduced CO2 emissions due to a decreased loss of mix and optimised transport enable a more sustainable construction method. ■ Fliegl Baukom www.fliegl.com Fliegl Bau - und Kommunaltechnik is part of the global Fliegl Group, based in Mühldorf am Inn, Germany. The company develops and manufactures products for the building industry and municipal companies. These include dump trucks, transport systems, water barrels, mixers and mixing plants.

ABOVE: With push-off technology, the material is pushed into the paver bit by bit, ensuring almost the same temperature composition over the entire duration of the unloading process BELOW: A Fliegl Thermo push-off trailer set-up helped optimise asphalt paving at Nikola Tesla Airport in Belgrade (image © SREMPUT DOO Ruma, Serbia)

“There is no risk of the Fliegl ASW Thermo tipping over - an important safety aspect on uneven construction sites”

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6D ROAD SCANNING Figure 1

ENTER THE SIXTH DIMENSION When it comes to pavement inspections, the future is likely to be 6D road scanning, explains XenomatiX chief executive Filip Geuens. his article considers a novel and effective approach to pavement inspection, referred to as 6D road scanning. It will give insights into how new sensors and AI-tools generate more valuable data for pavement management.

A fundamental problem for road inspection and road maintenance is the offset in time between cost on the one hand and return and responsibility on the other hand.

It is well-known that preventive maintenance extends the lifetime of a road, leading to a clear return-on-investment. Filling cracks and repairing defects avoids water infiltration that would affect the road’s foundation, leading to accelerated ageing.

The right repair at the right time easily shifts the need for expensive total road reconstruction from 30 years to 50 years, assuming preventive maintenance is started early enough. Meanwhile, large savings come 20 to 40 years later, well beyond the duration of political mandates. This is one of the reasons why roads under control of private firms with a long-term contract are so much better than public roads.

Since road-maintenance budgets are typically low compared to road-construction budgets, it is critical to know precisely when, where and how to intervene with repairs. A common mistake is to wait until an entire street needs repair. A recent case showed that the cost to a municipality for having its 250km roads fully inspected was lower

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than repaving 58m² of road surface. To know when to initiate repairs requires periodic inspections: once or twice per year, depending on traffic load and climate. Importantly, instead of looking for potholes, inspections should be done to find and fix defects before they turn into potholes. While potholes deteriorate quickly, it is often that the defect which created the pothole has been around for a long time. It is better to do less frequent but more thorough road inspections to find the defects that will turn into potholes.

COMFORT CHARACTERISTICS Road users typically worry only about the smoothness of a surface, while road owners should worry about the homogeneity of the surface. Smoothness determines the driving experience on a road. Potholes, waviness, subsidence and rutting, to name some common defects, make driving very unpleasant. We call these defects ‘comfort characteristics’. When these defects become noticeable, the road has already degraded seriously.

MAINTENANCE CHARACTERISTICS Road owners should worry about early-stage defects such as cracks, delamination and local subsidence. We call these ‘maintenance characteristics’. Proactive pavement management requires looking for defects that allow water infiltration or that indicate underground problems. Road users don’t ‘feel’

these defects when driving. Yet, if left alone, weather and traffic load will turn these early defects into more serious problems that affect smoothness.

Road authorities that base their pavement management on complaints from road users are fundamentally too late. They start looking at the problems when it is too late for preventive maintenance and the corresponding financial benefit.

SAFETY CHARACTERISTICS Apart from maintenance and comfort characteristics, there is a third characteristic, that of safety, specifically around road markings. There is an increasing importance of advanced driver-assistance systems ADAS - which often rely on good-quality road markings. Modern pavement inspection should include these road markings.

Meanwhile, for two-wheel mobility users, low-friction road marking is an area of concern because of a loss of traction for the wheels of a scooter or bicycle.

The three categories of defects require different types of measurement instruments.

Most inspection tools are suitable for only a small subset of road defects. That is why multi-functional vehicles have been created but this makes road inspection expensive and complex.

Over the past century, inspection tools for comfort characteristics have evolved as follows: bars, balanced wheel (later this www.worldhighways.com www.globalhighways.com

6D ROAD SCANNING

again, images are only two dimensional and suffer from distortion. Consequently, 2D images are not suitable for measuring and quantifying dimensions, such as length, depth and width of cracks.

The third method is the use of line lasers to find local defects. This approach is commonly used but can be very expensive and is only one part of a multi-functional vehicle.

Figure 2

Figure 3

became ‘vibration sensors’), point laser, line lasers and area lasers.

Bars across the road had to be placed manually. The distance from the bottom of the bar to the lowest point on the pavement had to be measured with a ruler; a very slow, random and inaccurate process.

The balanced wheel-measurement method involved the upward and downward movement of a wheel, typically mounted on a trailer pulled behind a vehicle. It gave a good measurement of the road’s evenness, but the mechanics were complex and it required a fixed driving speed.

The point laser (laser-distance sensor) method measured how a car body moves up and down relative to the road surface.

However, this gave a road profile for only one longitudinal section of the road. Hence, the steps to mounting multiple point lasers on a bar, returning multiple longitudinal profiles.

Since more point lasers added cost and complexity to the measurement process, the natural step was to switch to a line laser - the equivalent of an infinite number of point lasers next to each other. This gives good results in a transversal direction.

Unfortunately, combining consecutive line measurements into a complete road model proved very difficult because of the motion of the vehicle.

The logical next step was to spread the laser light over an entire surface, covering the road in transversal and longitudinal directions. www.globalhighways.com

Such area scanners collect a lot of data and represent the entire road shape in 3D very precisely.

Meanwhile, cameras have been employed for road measurements. However, there is not enough contrast in 2D road images to quantify the shape (geometry) of the road surface, even when applying techniques such as stereo-vision or structure for motion. A premium car brand even had to withdraw a stereo camera-based road-measurement system for suspension control after two years. Cameras can see road markings and cracks but are not suitable for noting comfort characteristics.

For maintenance characteristics, there are three common practices. By far the most common is visual inspection by a human but if they are walking for an inspection, then safety becomes an issue.

Another problem is that giving numerical values for quantifying the size and severity of the defects is not precise and may vary from inspector to inspector. If there are no repeatable numerical results, it is impossible to monitor the degradation over time and to decide on the right moment for preventive maintenance.

To overcome this problem, cameras have been used. But a common error has been to use inexpensive dash cams or to reuse images that were recorded for different purposes and, as such, do not cover the road sufficiently (mobile mapping data for example). Here

THE CONCEPT OF 6D The idea behind 6D road scanning is to address the aforementioned shortcomings, especially to eliminate human error. The proposed solution is the combination of a solid-state Lidar system and a high-resolution camera (see Figure 1). Lidar is an acronym for ‘light detection and ranging’ or ‘laser imaging, detection and ranging’. It is a method for determining ranges by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver.

Lidar provides 4D - a 3D point cloud plus the reflectivity of the road material. A point cloud is a discrete set of data points in space that may represent a 3D shape or object.

Meanwhile, a camera provides 2D images.

Fusing these two data sets in a perfect overlay creates rich 6D data for pavement analysis, hence the name 6D road scanning.

The word ‘scanning’ refers to the fact that the entire road surface is digitised when driving around with this sensor set (see Figure 2). As such, the results are independent from how the driving is done - speed, location on the road and motion of the car body. The scanning does not refer to the Lidar.

The proposed Lidar does not even have a scanning mechanism. It is actually a solidstate Lidar with no moving parts, meaning it can withstand mechanical and thermal effects from the car and the environment. Important also is the accuracy of the Lidar system. Most Lidars have centimetre accuracy. Clearly that is not sufficient because road inspections need to identify defects of around 0.5cm. The proposed solid-state Lidar has a measurement accuracy of 0.45mm.

Both the Lidar and the camera are pointed to the road surface and cover an area of about 4m x 4m behind the vehicle (see Figure 3, a standard passenger vehicle and an electric bike). The fused data delivers a detailed 6D road model. From this model, all relevant road characteristics can be derived.

Comfort characteristics basically require only 3D Lidar data. For quantification of rutting, a transversal section is taken and ROAD SURFACE TECHNOLOGY 2025

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a virtual straight bar is used to find the deepest point. Length and location of the bar are just parameters. So, rut depth and width for any road section or any length of bar can be computed.

The 3D model is used also for sizing potholes. The 3D computer model of the pothole can be used to calculate the surface, volume, average depth and maximum depth. The values are quantified with millimetre accuracy.

The pictures of the high-resolution camera come into play for crack detection.

By fusing the pictures with the Lidar point cloud, a 3D road model with the image resolution is created. Next, artificial intelligence does pattern recognition on this model to find cracks and also to classify and measure the cracks. Measuring means determining the width and length of the cracks. This allows calculation of the severity and density of the cracking in a numerically correct way.

Intensity, the 4D image returned by the Lidar, reveals road markings, as they reflect the laser light much more strongly than asphalt or concrete. Lane-wide intensity maps allow determination of the shape, location and quality of road markings.

Friction also can be quantified based on optical data. A high-resolution optical measurement of the road material reveals

how open or closed the surface is. A too smooth surface - at micro level - prevents the rubber tyres from having good grip on the road surface. Such measurements can be taken while driving, enabling continuous friction measurements.

6D road scanning generates georeferenced images of cracks, potholes and other surface defects directly after pavement collection. Each anomaly is automatically tagged with GPS coordinates, severityFigure 3 classification, IRI index and more. The pavement defect is stored digitally within a GIS system - geographic information system - or similar environment (see Figure 4).

This enables engineers to transition from manual survey logs to automated imagebacked condition records. This reduces subjectivity in inspections, improves repeatability and supports data-driven prioritisation of maintenance activities.

The approach, used by local authorities and surveyors, has consistently demonstrated strong return on investment by lowering field inspection costs and increasing efficiency in maintenance planning.

CONCLUSION Road authorities should systematically shift some budget from large road- (re) construction projects to preventive road maintenance. By doing so, a road’s life

expectancy goes up, the need for total road reconstructions will be reduced and a larger road network can be managed within the same budget.

Road inspection requires the precise quantification of road-defect types which, in turn, require multi-dimensional data. Camera-based or 2D inspection is insufficient; 3D data is required to detect and quantify road unevenness. Also, friction and road markings can be assessed based on laser measurements.

Finally, 6D road scanning combines Lidar, camera and artificial intelligence to measure and analyse all relevant road characteristics in a highly automated way, leading to productive and affordable road inspection. ■ XenomatiX https://xenomatix.com Filip Geuens is an engineer and chief executive of XenomatiX, based in Leuven, Belgium.

Under his leadership, XenomatiX developed multi-beam true solid-state Lidar systems that deliver high-precision 3D vision without moving parts. These enable safer autonomous driving, smarter road infrastructure management and more efficient digital mapping. He frequently speaks at international conferences, sharing insights on sensor technology and road digitisation.

Figure 4

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