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"Green Concrete“ Using the Properties of Concrete in Green Building Construction QGBC Villa- 28 June 2010- Doha, Qatar

Courtesy of: Mobil-Baustoffe GmbH

©Nadja Ortner-Ortner Consulting 2010


Current green building certification systems Green Globes

California Green Building Code

BREEAM U.K.

BREEAM Europe & International

DGNB

LEED

Source: PriceWaterhouseCooper

CASBEE (Japan) LEED, BREEAM Gulf

Green Star


Heating & Cooling

Lighting

• Efficiently using energy, water land and materials • Protecting occupant health and improving employee productivity • Reducing waste and pollution

Building Orientation

Transportation

Indoor Environmental Quality

Land use

Material Selection

Building Concrete Materials


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS

Development Density & Community Connectivity → Concrete is a preferred building material due to its energy efficient capabilities Daylight & Views → Concrete allows building large floors with none or few columns and shallow floor plates


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS  Brownfield Redevelopment→ for stabilization of contaminated soils Brownfield Redevelopment

Social Benefits

Economical Benefits • • • •

Jobs Income Taxes Business Opportunities

Source: City of Ottawa

• • •

Quality of Life Employment Area and Neighbourhood Renewal Housing Choices

Environmental Benefits • • •

Mitigration/elimination of health & safety risks Restoration of environmental quality Reduction of urban sprawl


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS  Construction Waste Management→ recycling construction waste (grey water and waste concrete)  Recycled Content in Building Materials → fly ash and slag cement (pre-consumer recycled); recycled concrete aggregate (post-consumer recycled)

REDUCE


Extraction of Raw Materials

Processing of Raw Materials

Deconstruction Material Reuse

Design for Construction

Occupancy Maintenance

Construction


LIFE CYCLE COST

ENVIRONMENTAL IMPACT

LIFE CYCLE ANALYSIS


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS  Usage of Regional Materials→ (500 miles radius) Concrete is always a ‘regional’ material as usually produced within 40km from site

40km


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS

 Protection or Restoration of Habitat→ used to build underground concrete parking garages and utilities  Maximization of Open Space→ concrete can be used to avoid retention ponds and to construct underground garages


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS  Water Efficient Landscaping- Innovative Wastewater Technologies- Water Use Reuse Reduction→ pervious concrete; concrete cisterns for rain water collection and process/grey water management systems

Source: Piedmont Triad Council of Governments.


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS

 Storm-Water- Quantity Reduction and Quality Control→ pervious concrete to minimize the disruption of natural hydrologic features (also support for vegetated roofs)

Source: Piedmont Triad Council of Governments.


SUSTAINABLE PROPERTIES OF CONCRETE IN BUILDINGS  Heat Island Effect- Roof/Non-Roof→ concrete used to minimize thermal differences on open spaces (shade or surface)

Source: Interlock Industries (Alberta) Ltd.


Materials Efficiency  can reduce “embodied” energy  can contribute to energy & water savings  Conversion of waste into reusable recycled materials  reduces use of natural resources  decreases pollution related to mining & manufacturing  Improved life-cycle costs  reduced costs for energy & water  durable materials last longer


Sustainable Properties of Concrete

• fully recyclable • good insulating properties (> steel; < wood)

• good energy storing properties thermal mass

large


Average CO2 embodied in Traditional Concrete Material

kg per m3 of concrete

% per m3 of concrete

kg of CO2 emitted per ton produced

kg of CO2 emitted per m3 of concrete

320

13.34

860

275.2

1,100

45.72

2.8

3.08

Fine aggregate

800

33.33

3.4

2.72

Admixture

2.5

0.12

150

0.38

Water

180

7.49

1.8

0.32

TOTAL

2,402.5

100

NA

281.7

Cement Coarse aggregate

Note: numbers excludes transportation- the average CO2 emission per m3 is 310 kg


CO2 Emissions in Concrete Life-cycle

Carbon Dioxide Emissions System Boundary

Admixtures Production

Diesel Fuel

LPG Fuel

Fine Aggregates Production

Cement Production

Unexploited Resources Fly Ash Processing

GGBFS Processing

Coarse Aggregates Production

Transport of Raw Materials to Concrete Batching Plants

Electricity

Explosives

Concrete Production

Transport of Concrete to Constructi on Site

Placement (Pumping) of Concrete on Site

One Cubic Meter of Concrete in Structure


Major environmental threat when batching concrete

High amount of GHG emissions released

CACO3â&#x2020;&#x2019; CAO+CO2


High amount of GHG emissions released

CACO3â&#x2020;&#x2019; CAO+CO2


CEMENT  world cement industry accounts for 5% of global anthropogenic CO2 emissions

 cement content of a standard concrete mix design represents : • ca. 85% of embodied energy • up to 96% of GHG emissions


CEMENT SUBSTITUTES

GGBS

produced from blast furnaces used to make iron (replacement level: up to 80%)

Fly Ash

by-product of coal-combustion from coal-burning power plants (replacement level: up to 60%)

Slag Cement

Blast- Furnace Cement (slag added to cement before mixing)

(CM3 - A or B)


CEMENT SUBSTITUTES Average Reduction of CO2 Emissions for Standard Mixes :

OPC + GGBS

OPC + Fly Ash

22%

CO2→ 52kg/ton

15%

CO2→ 4kg/ton


Proposed Cement Replacement Levels Concrete Application Concrete Paving Exterior Flatwork not exposed to deicer salts Exterior Flatwork exposed to deicer salts with w/cm â&#x2030;¤ 0.45 Interior Flatwork Basement floors Footings Walls & Columns Tilt-up panels Pre-stressed Concrete Pre-cast Concrete Concrete blocks Concrete pavers High Strength ASR mitigation Sulfate resistance Type II equivalance Type V equivalance Lower permeability Mass concrete

Cement 25 - 50% 25 - 50% 25 - 50% 25 - 50% 25 - 50% 30 - 65% 25 - 50% 25 - 50% 20 - 50% 20 - 50% 20 - 50% 20 - 50% 25 - 50% 25 - 70% 25 - 50% 50 - 65% 25 - 65% 50 - 80%


Reuse and Recycling of Waste Materials Up to 35kg/m3 of recycled solids can be used in mix

Cement content may need to be increased


Waste Concrete Recycling Methods  crushing concrete into recycled aggregates  washing out the waste concrete before the hardening begins- eco-friendly version, if wash-out water is recycled and reused  recycled concrete→ use in non structural elements such as backfills, blinding slabs, core filling, embankments and road construction


GREY WATER Grey (wash-out) water from cleaning of the equipment

Usually discharged into ponds where solids can settle out

Inefficient procedure and environmental hazard


GREY WATER Inefficient procedure and environmental hazard

 Grey water contains: • Cement • Other fines (GGBS, Fly Ash, sand < 0.1 mm)


GREY WATER SOLUTION Grey (wash-out) water from cleaning of the equipment

Usually discharged into where solids can settle out Installation ofponds Close-loop Systems

Inefficient procedure and environmental hazard Reduces Overall Grey Water


Environmental Training  Controlling air emissions and dust

 Storage and spill prevention of hazardous liquids  Management of process water  Management of solid waste


Concrete without Cooling  short time workability due to a faster setting process  extreme high concrete temperatures caused by heat of hydration at the setting process  uncontrollable cracking  high costs for intensive curing  extension of construction periods due to a production stop caused by high temperatures

Courtesy of: Mobil-Baustoffe


Threats due to High Fresh Concrete Temperature  Problems with mixing, correct placing and curing

 Thermal / differential thermal cracking of concrete  Decreased 28-days and later strengths

 Delayed Ettringite Formation (DEF) in concrete when exceeding a temperature of about 65°C during hydration, which can cause cracking even years after installation


Threats due to High Fresh Concrete Temperature

ď&#x201A;§ Delayed Ettringite Formation (DEF) in concrete when exceeding a temperature of about 65°C during hydration, which can cause cracking even years after installation


Cooling of Fresh Concrete Effect

Investment

Running Costs

Operation

North Orientation of Storage

low

low

low

-

Shading

low

low

low

Easy

Spraying with Water

low

low

low

Easy

Short Process Time for Extraction

high

low

low

-

low

medium

low

Easy

Crushed Ice Instead of Mixing Water

medium

high

medium

Difficult

Cooling Cement by LN in Storage Silo

high

low

high

Easy

high

high

high

Easy

medium

low

very high

Difficult

high

high

low

Medium

PASSIVE MEASURES FOR AGGREGATES

ACTIVE MEASURES Chilled Mixing Water

Cooling Cement by LN in Heat Exchanger Cooling Concrete by LN in Mixer Trucks

Cooling Aggregates in Water Bath


Flake-Ice Cooling

ď&#x201A;§ At high temperatures further activities are needed; such as shading the aggregates or the production of concrete during the cooler night time period ď&#x201A;§ Lower production capacity due to a limited ice production and a long mixing process.

Courtesy of: Mobil-Baustoffe


SAMPLE MIX Cement 360kg w/c ratio < 0.38 humidity in sand 8% =60l maximum water content= 137l

concrete temperature without cooling= 45°C cooling 1°C = 7.5kg of ice


SAMPLE MIX  Maximum possible addition of water:

77 litres  Fresh concrete temperature after adding flake ice:

34°C

=


Coarse Aggregate Cooling  More time to place and finish concrete works on site  Significant energy savings  Reduced dust emissions  Reduced admixture usage  Cement savings (low w/c ratio)  Achieving concrete temperatures as low as 25 Degree Celsius.  Reduces the risk of rejected concrete due to temperatures out of specification

 Transportation over distances possible Courtesy of: Mobil-Baustoffe

longer


Aggregate & Cement Cooling

 Cement cooled down by 10 °C results in a reduction of the overall concrete temperature of 1 °C  Methods: • Air • Nitrogen or carbon dioxide

Courtesy of: Mobil-Baustoffe


TEMPERATURE DEVELOPMENT- COOLING METHODS 90

80

70

Temperature in Degree Celsius

60

50 Without cooling

Flake-ice cooling

40

Aggregates cooling Aggregates & cement cooling

30

20

10

0 Fresh Concrete Temperature Site Concrete Temperature

Cooling Method


Cooling Method Comparison: 1500 m3 of Concrete in 24h (as per mix and air temperatures from previous sample)

Conventional flake- Energy saving flakeice cooling ice cooling

Coarse aggregate cooling system

805 kW/h per unit

665 kW/h per unit

350kW/h per unit

2012 kW/h

1662 kW/h

350 kW/h

1kW = 0,32 l Diesel 1 Ě&#x160;C= 7.5kg of ice/m3

15456 l/day

12768 l/day

2688 l/day

10,3 l per m3

8,5 l per m3

1,8 l per m3


office@ortner-consulting.com www.ortner-consulting.com


Tue use of Concrete in Green Building Construction