SUSTAINABLE SOLUTIONS IN CONCRETE INDUSTRY GSAS Sponsored Seminar / Workshop

SUSTAINABLE SOLUTIONS IN CONCRETE INDUSTRYGSAS Sponsored Seminar / Workshop

MEETING TODAY’S DEMANDS BY ADOPTING THE LOW CARBON CONCRETE REVOLUTIONChristopher Stanley, Technical Director, Unibeton

Qatar National Convention Centre, Doha – Qatar 24th May 2014

Sustainable Solutions in Concrete Industry 2

• Producing great structures that last

• Using least possible energy both during construction and remaining service life. Embedded CO2 and operational CO2 need to be considered

• Eliminating future maintenance costs. 120 year design life can now be extended to 400 years.

• Leaving a better world to our children

• Better durability: against chlorides, sulphates, ASR, acid attack

• Better colour – high light reflectance

What is Sustainability?


Sustainability Development






• Low Carbon Concrete is a GREEN concrete. That does not mean concrete that has not yet hardened, or is coloured with green pigment, but in the context of this presentation green concrete is taken to mean environmentally friendly concrete.

• This means concrete that uses less energy in its production & produces less carbon dioxide than normal traditional concrete.

What is Low Carbon concrete?


• The main ingredient in cement is Limestone (Calcium Carbonate CaCO3 )

• During manufacture the ingredients are heated to about

1200oC

• During this process the Carbon Dioxide is driven off :

CaCO3 = CaO + CO2

• 1kg of cement releases 700gms -1kg of Carbon Dioxide into the atmosphere during its manufacture

Where does the Carbon Dioxide come from inconcrete?


• Most of CO2 in concrete is from the cement manufacturing process (1 kg of cement produces about 1 kg of CO2 or 5 m3 of CO2)

• Low Carbon Green concrete makes more effective use of cement giving a reduced carbon footprint and therefore protects the environment.

• Low carbon green concrete = effective use of cement means better not lower quality

Low Carbon Green concrete


CO2 and production energy


CO2 Emissions from industry


3.5kg of cement produces enough CO2 to fill this balloon


A typical 40N concrete mix generates 100 balloons of CO2 per cubic metre of concrete


Calculation of CO2 for a Typical 40MPa Concrete


GGBFS (say 70%) = 294 kg x 0.109 = 32 kg of CO2/m3

126 kg of cement x 0.797 = 100.42 kg CO2/m3

= 32 kg CO2/m3 + 100.42 kg CO2/m3 = 132.42 kg CO2/m3

REPRESENTING A REDUCTION OF 201.58 kg CO2/m3

If some of the cement in the mix was replaced with GGBFS


25% PFA = 105 kg x 0.06 = 6.3 kg of CO2/m3

+ 315 kg of cement x 0.797 = 251.06 kg CO2/m3

Total of 257.66 kg, or a saving of 76.35 kg of CO2 replacing 25% of the cement with PFA

A 25% replacement of Portland Cement with PFA


• Cement production accounts for 6% of all CO2 emission which is claimed to be one of the factors influencing global warming.

• In 2013 Qatar was the highest cement consumer per capita in the world.

• 1 Qatar 3.9 tonnes/year/capita

2 UAE 2.6 tonnes/year/capita

3 Kuwait 2.2 tonnes/year/capita

8 Saudi Arabia 1.4 tonnes/year/capita

40 Oman below 0.6 tonnes/year/capita

Low Carbon Green concrete


• Highly optimized mix design• Self-compacting concrete• Ground granulated blastfurnace slag• Pulverised fly ash. (Pfa)• Portland limestone cement• Rice husk ash cement• Rice husk cement• Cement free concrete• Concrete wood• Low cost construction

LOW CARBON GREEN CONCRETE OPTIONS


Better Performance• Enhanced cohesion workability, finishability and

consistency• Reduced shrinkage / creep. Lower compressive

strength SD• Durability - Increased service life of concrete

Greater Value• Minimizes amount of steel needed• Higher MOE can allow reduced section thickness

weight• Optimizes use of available materials

Greener• LEED Contributes to Certification points• Reduced carbon footprint• Affordable “green” alternative

Optimized Concrete Means Value Engineering


Mix optimization; A New Approach


Mix optimization


The basis for optimization is that the small particles can fill the space between the large ones to minimize the void content which creates maximum stability.

MIX OPTIMIZATION


Particle packing – voids content (1)


Particle packing – voids content (2)


Aggregates – natural angle of repose


Slump test - 20mm aggregate


Slump test – Dune sand


• The slump of the concrete and its flow are a function of the angle of repose, shape & the quantity of the predominant size of the aggregate in the mix.

• Use of more fine aggregate, because of the smaller angle of repose, gives higher slump & flow.

• But the optimum proportions of coarse & fine aggregate are critical to the properties of both fresh & hardened concrete.

Aggregate proportions affect the properties of concrete


“Particle-Packing Optimization” to meet requirements of plastic and hardened properties”


Typical spread of an optimized mix – note theaggregate distribution & that it does not bleed





Life Cycle Analysis


• The heat of hydration of optimized modified concrete is significantly lower than traditional concrete

• This results in a lower temperature rise in large concrete pours which is a distinct advantage.

• The peak temperature rise can be reduced by up to about 14oC.

Heat of hydration


A typical 40N optmized mix produces only 27 balloons of CO2 per cubic metre of concrete


Better performance• Enhanced workability,finishability & consistency

• Reduced creep & shrinkage

• Increased service life

Greater value• Minimises amount of reinforcement

• Higher Modulus of Elasticity – reduced thickness

• Ease of compaction – less labour

Greener• Contribution towards LEED Certification points

• Upto two ESTIDAMA points in UAE

• Reduced Carbon Footprint

• Affordable Green construction

Low Carbon Optimized Green concrete gives value engineering


Embodied GHG - Estidama


Concrete Mix Design




• Unibeton is now developing a technology to make very green concrete, sometimes even without Portland Cement, using a special process. This concrete will produce only about 7 balloons of CO2 per cubic metre. The concrete sets and hardens like Ordinary Portland Cement. It has a one day strength of about 22MPa and 28day strengths of 60 – 75 Mpa can be achieved.

VERY GREEN CONCRETE


• By 2050 global use of cement likely to be 5,000Mt (steel will be 8,000Mt).

• No-cement concrete could be 1/3rd so 1,666Mt or 4,700Mm3 of cement-free concrete.

• Highly likely that PFA and other byproduct pozzolans will increasingly make “greener” concrete and reduce embedded CO.

No-cement concrete


• Use a cement replacement (binder) based on the activation of ground granulated blast furnace slag (GGBS) and pulverised fuel ash (PFA) byproducts.

• Both are widely available and relatively inexpensive.

• GGBS and PFA must be activated to produce a binder. There are recently invented new types of activators.

• Resulting binder used in much the same way as Portland Cement without the carbon legacy.

Our solution


• Sets chemically with very low heat of hydration

• Vast areas poured without joints- increased productivity

• No early-age thermal cracking – take out reinforcement

• 30 MPa in 7 days, >50 MPa at 90 days, and >70MPa at 365 days

• Greater dimensional stability – low shrinkage and creep

• Resistant to chloride, sulphates and acids

• Maintenance-free. Much extended service life

• Complies with performance based standards such as ASTM C1157 Low Heat Concrete category

No Cement ConcreteThe technical advantages


VERY GREEN CONCRETE




Green Pre-stressed Concrete 64MPa at 28days


• Cost similar to most concrete used in GCC containing Slag or PFA

• Green alternative only 7% of carbon footprint of traditional OPC concrete

• Significant Carbon Credits due to reduction of CO2 emissions

• Track record of use in pre-tensioned pre-stressed concrete in USA

Green Pre-stressed Concrete Advantages


• Green cement free concrete can currently be produced in strengths ranging from 20MPa to over 75MPa

• Current pre-stressed production normally calls for a concrete strength of 24MPa at the time the tendons are released and with a final strength of in excess of 35MPa.

• The early strength gain can be adjusted to suit the production process but is normally in the region of 24hr-48hr before tendon release.

Green Pre-stressed Concrete Advantages


Green Pre-stressed Concrete












THREE MILLION TONNES OF GGBFS WILL PRODUCE 7.8 MILLION TONNES OF GREEN LOW-CARBON CONCRETE.

THAT IS EQUIVALENT IN TERMS OF REDUCED CO2 TO:• TAKING 800,000 CARS OFF THE ROAD

• 85,000 SPACE SHUTTLE LAUNCHES

• SAVING 2.5 MILLION TONNES OF CO2 BY NOT USING PORTLAND CEMENT

• SAVING CO2 NEEDED TO SUPPLY 3.8 MILLION HOUSES WITH HOT WATER


• Take out crack control reinforcement (saving up to 30% steel)

• Reduce binder content using performancebased specifications to achieve C40, C50, C60 … concretes

• Reduce concrete cover by 10mm by Q C measures on site. Use Eurocode 2:1992:1-1; 2004 Clause 4.4.1.3

• Sustainability and durability are compatible. We can use the enhanced properties of concrete to avoid over-design

Doing more with less


• Reduced energy consumption

• Reduced CO2 emissions

• Diversion of industrial by-products from landfilling• Lower water consumption• Reduced steel use

Environmental advantages


Recently finished 10,000 sq ft (1,000 sqm) warehouse – Cambridge, Laid in one day with no joints.


This large scale field trial was conducted for Crossrail in East London. It marked the first occasion that No Cement Concrete concrete was pumped.

Large Scale Field Trials


• FOR EVERY m3 OF NO CEMENT CONCRETE, 281 KG OF EMBEDDED CO2 ARE REDUCED

• THE EMPIRE STATE BUILDING WAS CONSTRUCTED FROM 47,400 m3 OF CONRETE. IF IT HAD BEEN CONSTRUCTED FROM NO CEMENT CONCRETE = A SAVING OF 13,319 TONNES OF CO2

• IT TAKES 1.87 TONNES OF CO2 TO FLY ONE PASSENGER FROM LONDON TO QATAR OR 7000 RETURN FLIGHTS FROM LONDON TO QATAR WOULD BE THE SAVINGS IN CO2 BY BUILDING THE EMPIRE STATE BUILDING IN CEMENT FREE CONCRETE RATHER THAN TRADITIONAL CONCRETE.


Substantially reduced CO2 emissions and energy use in the construction sector

Utilisation of by-products which would be otherwise land filled (certain geographical locations, India, China etc;)

Improved durability because:• Much decreased capillary porosity (prevents ingress of

aggressive chemicals, including chlorides, acids and sulphates, into concrete)

• Much denser cement-aggregate interface (reduces permeability)

• Much better bond to steel reinforcement

Advantages of using No Cement Concrete





Concrete Spring!




THANK YOU

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SUSTAINABLE SOLUTIONS IN CONCRETE INDUSTRY GSAS Sponsored Seminar / Workshop