1. SUSTAINABLE SOLUTIONS IN CONCRETE INDUSTRY
GSAS Sponsored Seminar / Workshop
MEETING TODAY’S DEMANDS BY ADOPTING THE LOW CARBON CONCRETE REVOLUTION
Christopher Stanley, Technical Director, Unibeton
Qatar National Convention Centre, Doha – Qatar
24th May 2014

2. What is Sustainability?
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

3. Sustainability Development

4. Sustainability Development

5. Sustainability Development

6. What is Low Carbon concrete?
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.

7. Where does the Carbon Dioxide come from in 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

8. Low Carbon Green concrete
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

9. CO2 and production energy

10. CO2 Emissions from industry

11. 3.5kg of cement produces enough CO2 to fill this balloon

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

13. Calculation of CO2 for a Typical 40MPa Concrete

14. If some of the cement in the mix was replaced with GGBFS
GGBFS (say 70%) = 294 kg x = 32 kg of CO2/m3
126 kg of cement x = kg CO2/m3
= 32 kg CO2/m kg CO2/m3 = kg CO2/m3
REPRESENTING A REDUCTION OF kg CO2/m3

15. A 25% replacement of Portland Cement with PFA
25% PFA = 105 kg x 0.06 = 6.3 kg of CO2/m3
+ 315 kg of cement x = kg CO2/m3
Total of kg, or a saving of kg of CO2 replacing 25% of the cement with PFA

16. Low Carbon Green concrete
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 tonnes/year/capita
2 UAE tonnes/year/capita
3 Kuwait tonnes/year/capita
8 Saudi Arabia 1.4 tonnes/year/capita
40 Oman below 0.6 tonnes/year/capita

17. LOW CARBON GREEN CONCRETE OPTIONS
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

18. Optimized Concrete Means Value Engineering
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

19. Mix optimization; A New Approach

20. Mix optimization

21. 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.

22. Particle packing – voids content (1)

23. Particle packing – voids content (2)

24. Aggregates – natural angle of repose

25. Slump test - 20mm aggregate

26. Slump test – Dune sand

27. Aggregate proportions affect the properties of concrete
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.

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

29. Typical spread of an optimized mix – note the aggregate distribution & that it does not bleed

33. Life Cycle Analysis

34. Heat of hydration
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.

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

36. Low Carbon Optimized Green concrete gives value engineering
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

37. Embodied GHG - Estidama

38. Concrete Mix Design

41. VERY GREEN CONCRETE
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.

42. No-cement 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.

43. Our solution
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.

44. No Cement Concrete The technical advantages
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

45. VERY GREEN CONCRETE

48. Green Pre-stressed Concrete 64MPa at 28days

49. Green Pre-stressed Concrete Advantages
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

50. 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.

51. Green Pre-stressed Concrete

55. Green Pre-stressed Concrete

56. Green Pre-stressed Concrete

57. Green Pre-stressed Concrete

59. THAT IS EQUIVALENT IN TERMS OF REDUCED CO2 TO:
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

60. Doing more with less
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
Sustainability and durability are compatible. We can use the enhanced properties of concrete to avoid over-design

61. Environmental advantages
Reduced energy consumption
Reduced CO2 emissions
Diversion of industrial by-products from landfilling
Lower water consumption
Reduced steel use

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

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

64. 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.

65. Advantages of using No Cement 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

69. Concrete Spring!