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ADHEBIT Anti-stripping Agents

A new generation of adhesion promoters that combines superior coating and exceptional workability with immediate commercial saving


An asphalt road paving consists of a mixture of "stone aggregates" with a specific granulometric curve and a bitumen binder.

+ 95%

5%

The production takes place in specific plants, mixing the ingredients at a temperature that can ensure a suitable viscosity for obtaining a homogeneous asphalt. It is than transported to the work site and laid using an asphalt paver and compaction rollers, maintaining the asphalt mix at a suitable temperature for laying.


The choice of aggregates depends on the technical requirements of the final asphalt layer. Chemically they can be “acidic”, in which case they have the surface characteristic to attract negative charges or “alkaline”, in which case they will attract positive charges. The “acid” aggregates are characterized by a high content of silica, while the “basic” ones contain carbonates.

basic

acid

Limestone

Basalt Diorite Sandstone Granite

Quarzite 0%

50% Silice Content

100%

Bitumen is a mixture of hydrocarbon residues from the distillation of crude oil. It is a complex mix of chemical substances, characterized by the presence of molecules with low polarity. The adhesive properties of the bitumen are strictly connected to the presence of acid groups, for this reason, a bitumen with high acidity has better adhesion properties than a neutral bitumen. www.activasrls.com 3


The life of an asphalt pavement depends basically on the adhesion between the bitumen and the aggregates, and it is the result of the ability of the bitumen to resist to static and dynamic stresses caused by traffic and by the action of the atmospheric agents such as air, light and water.

The adhesion between bitumen and aggregates represents the critical point of the entire construction of a road paving process. Bitumen has a low polarity and a minimum chemical affinity with the aggregates, as a consequence, the bitumen cohesion is superior to the bitumen/aggregate adhesion. With the presence of high -stress and the action of water, the bitumen film covering the aggregates can detach, compromising the bitumen/aggregate bond and the structural decay of the road paving begins.


The adhesion between bitumen and aggregates can be interpreted by evaluating the wetting, that is the process that brings the bitumen and the stones surface into contact. Air Bitumen

Ɵ = Contact angle

Stone surface

This system is explained by the contact angle, defined as the angle formed by the tangent of the bitumen-air interface, and the tangent of the solid surface, in correspondence to the three phases contact line.

Bitumen

Bitumen

Stone surface

Stone surface

Ɵ = 180° Wetting: Null

90°< Ɵ <180° Wetting: Low

Bitumen

Stone surface

0°< Ɵ <90° Wetting: High

Stone surface

Ɵ = 0° Wetting: Perfect www.activasrls.com 4


ADHEBIT The affinity between bitumen and aggregates can be improved by the addition of a small amount of ADHEBIT additive. This additive consists of a chemical substance called “surfactant” that has the role of lowering the surface tension of the bitumen, facilitating the wetting of the stone aggregates surfaces, promoting the adhesion between bitumen and aggregates.

Hydrophilic head groups “polar”

Hydrophobic tails group “non polar”

The chemical substance consisted in ADHEBIT is an organic compound with a particular chemical structure, characterized by very long molecules consisting in a “polar” group and a “non polar” group.

ADHEBIT, added in small quantities to the bitumen, has the tendency of disposing itself with the “polar” head group of the molecule in contact with the air and the “non polar” tails anchored into the bitumen.

Bitumen


When bitumen comes into contact with the aggregates surface, the ADHEBIT molecules are absorbed, aligning themselves into a “monolayer” film; with the “hydrophilic” head groups absorbed by the aggregates’ surface, and the “hydrophobic” tails of the molecules anchored into the bitumen.

Bitumen

Aggregate

The presence of ADHEBIT modifies the surface tension between bitumen and aggregate reducing the contact angle. A smaller contact angle helps the adhesion of the bitumen to the stone surface, enables the wetting of the fine parts and above all, facilitates the bitumen to enter into the microscopic crevasses on the aggregate surface. ADHEBIT also helps prevent the bitumen stripping from the aggregates’ surface.

Bitumen Bitumen

ADHEBIT Angle = 90° ÷ 150°

Angle = 0° ÷ 90°

Wetting Adhesion

Wetting Adhesion

: POOR : POOR

: HIGH : EXCELLENT

HIGH WETTING During the mixing phase of asphalt, bitumen is able to fully cover the aggregates, even in presence of water and moisture. This action is called «active adhesion». EXCELLENT ADHESION The bitumen film has a perfect bond to the aggregates and it has a longterm resistance. This action called “passive adhesion”, represents the ability of bitumen to remain attached to the surface of the aggregates for the entire road service life (stripping resistance). www.activasrls.com 6


ACTIVA offers two types of â&#x20AC;&#x153;adhesion promoterâ&#x20AC;? additives both characterized by high quality and high performance:

ADHEBIT HA-573 It is an anionic surfactant based on phosphoric esters, with very high performance that guarantees a perfectly stable bond between bitumen and aggregates under any condition of application (moisture, low temperatures, acid aggregates, basic aggregates, etc.)

ADHEBIT LA-188 It is an anionic surfactant based on phosphate esters with unique features, because it is not classified as hazardous for human health and for the environment. ADHEBIT LA-188 gives the asphalt: great workability, ease of compaction and an exceptional adherence.


Production Benefits The use of ADHEBIT guarantees the coverage of the aggregates difficult to be coated and ensures a perfectly stable bond between bitumen and aggregates (acids and/or basics). The use of ADHEBIT:  Promotes bitumen/aggregate adhesion.  Increases the “stripping” resistance, in other words it prevents the detachment of the bitumen film.  Improves the aging resistance, slowing down the oxidation process of the bitumen. ADHEBIT is added directly into the mixer during the production of an asphalt mix, using an automatic dosing system. Alternatively, it can be added directly in the storage tank of the bitumen while it is being loaded; this operation must be conducted so that the additive is added at the same time as the bitumen, making sure that at the end of the transfer of bitumen, the right quantity of additive has been added to the storage tank. The first solution is much more advantageous, since it avoids the modification of the whole bitumen stored in the tank, and gives higher flexibility as it allows to vary the dosage depending on the working conditions. The dosage rates depend on the nature of the aggregates and the bitumen type used. Usually they vary from 0,1% to 0,3% of the bitumen weight; this means that for 1.000 kg of bitumen there are required between 1 and 3 kg of ADHEBIT.

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The adhesion between bitumen and aggregates can be evaluated by laboratory testing. The European and International Standards are based on the analysis of the bitumen/aggregates compatibility and on the indirect loss of tensile strength of the asphalt after immersion in water.

The norm EN 12697-11 is applied to determine the affinity between bitumen and stones. In particular, Part A, known as "Rolling Bottle Test", states that the aggregates must first be coated with hot bitumen and then put in glass bottles filled with distillated water at room temperature. The bottles spin for 24 hours at a certain velocity and after six and twenty-four hours the samples are analyzed, by a visual assessment giving a percentage of aggregate coverage.

DETERMINATION OF THE AFFINITY BETWEEN AGGREGATE AND BITUMEN EN 12697-11 PART A â&#x20AC;&#x201C; ROLLING BOTTLE METHOD 100 90

Coverage [%]

80 70 60 50 40 30

20 10 0 0

6 Tal Quale

12 0,1% AdheBit LA-188

18

Tempo [ore]

24

0,2% AdheBit LA-188

The graphic shows the percentage of aggregate coverage (granite 8/11 mm), respectively: with 50/70 bitumen without additive; with 50/70 bitumen modified with ADHEBIT LA-188 0,1% and 0,2% on bitumen weight.


With the laboratory test EN 12697-11 Part C (ASTM D3625), known as "Boiling Test", the aggregates are first coated with hot bitumen and then immersed in boiling water for ten minutes. Later on, the aggregates are evaluated, by a visual assessment giving a percentage of aggregate coverage. DETERMINATION OF THE AFFINITY BETWEEN AGGREGATE AND BITUMEN EN 12697-11 PART C – BOILING WATER STRIPPING METHOD* 100 90

Coverage [%]

80 70 60 50

40 30 20 10 0 10 min Tal Quale

20 min 0,2% AdheBit HA-573

30 min 0,3% AdheBit HA-573

The graphic shows the percentage of aggregate coverage respectively : with 50/70 without additive; with 50/70 bitumen modified with ADHEBIT HA-573 0,2% and 0,3% on bitumen weight. Both standards, the European norm (EN 12697-11) and the American norm (ASTM D3625) predict an immersion time, in boiling water, of 10 minutes; In ACTIVA’s laboratory, in order to make the test much more severe, we’ve increased the immersion time to 20 and 30 minutes. www.activasrls.com 10


The water sensitivity of bitumen mixtures is expressed as the “Indirect Tensil Strenght Ratio” (ITSR) calculated as the ratio of the “indirect tensile strength” (ITS) of wet specimens that have previously been immersed in a water bath at 40°C for 68 -72 hours, and the “Indirect tensile strength” of dry specimens of the same mix.

ITSR = 100 x

ITS wet ITS dry

“Indirect Tensile Strenght” (ITS) is the maximum tensile force that a specimen can withstand (EN 12697-23), while for "dry specimens" it is meant, specimens kept at laboratory humidity and temperature.

DETERMINATION OF THE WATER SENSITIVITY EN 12697-12 100 90 80

ITSR [%]

70 60 50 40 30 20 10 0

50/70 Bitumen

50/70 Bitumen + 0,3% AdheBit HA-573

50/70 Bitumen + 0,3% AdheBit LA-188


Benefits at a glance  Promotes Bitumen/Aggregates adhesion  Ensures a perfectly stable bond between Bitumen and Aggregates.  Extremely small dose (0,1% - 0,3% on binder weight).

 Improves asphalt water resistance.  Improves the asphalt workability during paving and compaction phases.

 Improves the asphalt workability in extreme weather conditions.  Reduces the production costs, allowing a reduction of the content of bitumen in the asphalt mix.  Excellent coating (wetting): bitumen, during the mixing phase and manufacture, perfectly covers the aggregates. This action is called "Active adhesion". The bitumen, even in the presence of water and moisture, smoothly covers the aggregates.  High stripping resistance: the bitumen film that covers the inert is perfectly fixed and enduring in time. This action defined as "passive adherence", represents the ability of the bitumen to remain attached to the surface of the aggregates for the entire useful life of the pavement.

 Antioxidant: the presence of special chemical compounds, slows down the natural process of oxidation of the bitumen. The antioxidant action decreases phenomena related to fragility and rapid aging pavement resulting in a longer conglomerates life. www.activasrls.com 12


www.activasrls.com

All product information is based on our current knowledge and experience and does not involve the assumption of guarantee and/or liability on the final result of work. In relation with the real work conditions, which may affect the functionality of our products, our indications do not exempt the customer from the responsibility checking the suitability of the products for the use and the purposes requested through preventive tests. In no event does Activa Srls assume responsibility for damages or losses of any kind or nature arising from the use of this information. By virtue of the continuous development of Activa products, the information contained in this catalog are subject to change without notice. Rev. 08-2018

ACTIVA S.r.l.s. Zona Industriale - Settore 3 87064 Corigliano-Rossano (CS) Italia Phone +39 0983 851070 E-mail info@activasrls.com

AdheBit (eng)  

A new generation of adhesion promoters that combines superior coating and exceptional workability with immediate commercial saving

AdheBit (eng)  

A new generation of adhesion promoters that combines superior coating and exceptional workability with immediate commercial saving

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