1. SUSTAINABLE CONCRETE TECHNOLOGY – CHALLENGE AND OPPORTUNITY
Dr. Tony C. Liu Dr. Jenn-Chuan Chern
Visiting Research Fellow Distinguished Professor
National Taiwan University, Taiwan, ROC

2. Presentation Outline Challenges facing concrete industry
Sustainable Concrete Technologies
Improved cement manufacturing technology
Use of supplementary cementing materials
Recycle and reuse of concrete
Enhancement of service life
Research and use of emerging technologies
Conclusions

3. Low Material Cost
Low Construction Cost
Low Maintenance Cost
Good Durability

5. Concrete Production in Taiwan (2007)
65 million m3
150 million Tons
1% of total world concrete production
0.3% of world population
6.5 tons/person

6. Challenges Facing Concrete Industry (1/2)
Population will continue to increase
6.7 billion in 2008
10 billion in 2050
Most of the populations are in Asian region
Infrastructure needs will grow
Provide needs of the increasing population
Aging and deteriorating infrastructure
Repair and rehabilitation needs are increasing

7. Challenges Facing Concrete Industry (2/2)
Natural resources and non-renewal energy are becoming scarce
3 billion tons of limestone
13 billion tons of aggregates
64 billion GJ of energy (fossil fuel and electricity)
Urgent need to reduce “greenhouse” gas emission to combat global warming
7% of the total world CO2 emissions from cement production
11% of the greenhouse gas emissions from life cycle of concrete and concrete structures

8. How Can We, the Concrete Industry, Meet the Challenges?
We need to adopt sustainable concrete technologies to meet the infrastructure needs, to save energy, to reduce CO2 emissions, and to protect environment

9. Sustainable Concrete Technologies
Reduce environmental impacts of cement production
Greater use of supplementary cementing materials
Recycle and reuse of concrete
Enhancement of service life of concrete structures
Research and use of emerging technologies

10. Reduce Environmental Impacts of Cement Production

11. Asia’s Increasing Share of Consumption of Cement
From Prof. Ouchi

12. Consumption of Cement in Asian Regions
From Prof. Ouchi

13. Use of Cement, Slag, and Fly Ash in Taiwan (2007)
13.5 million tons
GGBF Slag
5 million tons
Usage Rate: 100%
Fly Ash
4 million tons
Usage Rate: 70%

14. Environmental Effects of Cement Production
Emission of CO2
Each ton of cement contributes one ton of CO2
High energy use (fossil fuel and electricity)
4GJ of energy per ton of finished cement
Use of natural raw materials
Each ton of cement requires 1.5 tons of limestone
How can we reduce the environmental impacts of
cement production?

15. Reduce Environmental Impacts of Cement Production
Placing wet production facilities with modern dry-processing plants
Greater use of alternative fuels (petroleum coke, used tires, rubber, paper waste, waste oil, etc)
Greater use of recycled mineral by-products as raw materials in the cement kiln.
Decreasing electricity consumption during milling of cement by modernization of machinery.

16. Greater Use of Supplementary Cementing Materials (SCM)

17. SCM – The most Sustainable Construction Materials
SCM: Fly Ash, GGBF Slag, Silica Fume
Recovers industrial byproduct
Avoids disposal
Reduces portland cement
Decreased use of energy
Decreased greenhouse
gas emission
Decreased use of
virgin materials
Improves durability

18. Fly Ash in Concrete
About 600 million tons annually world-wide (10-15% used in concrete)
Better workability
Reduce temperature rise
Improve durability
High-performance, high-volume fly ash concrete

19. High-Performance, High-Volume Fly Ash Concrete
Fly ash replacement >50%
Low water content <130 kg/m3
Cement content <200 kg/m3
W/CM = 0.30 or less
Use HRWRA
Excellent long-term mechanical and durability properties

20. Ground-Granulated Blast-Furnace Slag
World production of slag – 100 million tons
Granulated form – 25 million tons
Utilization rate as a cementitious materials has increased in recent years and this trend is expected to continue
Blended slag cement (50% slag content)

21. Use of GGBF Slag in Taiwan
5 million tons of GGBF slag were used in concrete mixtures in 2007
High Volume slag concrete (55% to 45% of slag replacement rate) was commonly used in Taiwan for applications where high or moderate sulfate resistance is required

22. High Volume Slag Concrete
High volume GGBF slag in superplasticized concrete
Excellent mechanical properties
Good resistance to carbonation
Good sulfate resistance
Good resistance to penetration of organic liquids
Good freezing and thawing resistance (without air entrainment)
Good salt scaling resistance

23. Silica Fume Condenses from furnace gases
20,000 x
By-product of silicon metal or ferrosilicon alloy production
Smooth, spherical, glassy particles
0.1 to 0.15 micron, about 1/100
the size of cement particles
Worldwide production - 2 million tons

24. Applications of SF Concrete
Property-enhancing applications
Ultra High Strength Requirements
High Abrasion Resistance
Early-Age Strength Improvement
Corrosion Protection
Repair applications
1600 m3 of silica fume concrete was placed in 1983

25. Major Barriers Against the Use of Large Quantities of SCM
Prescriptive-type of specifications and codes
Limit on the use of SCM
Minimum cement content
Strength requirement at early age (28 days rather than 56 days or longer)
Education and Technology Transfer
Need to develop performance-based specifications and codes that will accelerate the rate of utilization of SCM

26. Recycle and Reuse of Concrete

27. Construction & Demolition (C&D) Waste
1 billion tons of C&D waste (broken concrete, bricks, and stone) are generated annually worldwide
10 million tons of C&D waste generated annually in Taiwan

28. Use of Construction & Demolition (C&D) Waste
Used mainly for road base and sub-base materials
Also used as partial replacement of coarse aggregate for structural concrete
Increased attention in European countries, Japan, U.S., and Taiwan

29. Recycling Other Materials in Concrete
Foundry sand
Cupola slag from metal-casting industries
Glass
Wood ash from pulp mills
Sawmills
De-inking solids from paper-recycling companies

30. Future Outlooks for Recycling
Local natural aggregate sources are scarce
Suitable landfill sites are becoming scarce
Improvements in demolition, processing, and handling technologies will improve the quality and decrease the cost of recycled concrete aggregates
Availability of design and construction specifications for recycled concrete

31. Enhancement of Service Life

32. Existing Infrastructure Conditions
Significant parts of the world infrastructure are aging and deteriorating
Overall grades of infrastructure report cards
USA (ASCE) D
UK (ICE) D+
Australian (EA) C+
S. Africa (SAICE) D+

33. Causes of Premature Deterioration of Concrete Structures
Electro-chemical
Corrosion of embedded metals
Physical
Freezing and thawing
Erosion
Shrinkage
Thermal stresses
Chemical
Acid attack
Sulfate attack
ASR
Poor-quality concrete will deteriorate prematurely and will require costly repairs and waste of natural resources and energy

34. Durable Concrete Structures
Large savings in natural resources and energy can result if the concrete structures are much more durable
Extending service life of the existing infrastructure instead of removal and rebuild requires less natural resources and energy
Use life-cycle cost approach by seeking better and durable concrete structures rather than lower initial cost

35. Research and Use of Emerging Technologies
Emerging technologies that have the potential to significantly contribute to sustainable concrete industry
Repair and Rehabilitation technology
Ultra-high strength concrete
Nanotechnology

36. Repair and Rehabilitation Technology
Evaluation Tools and Modeling Technologies
New and improved NDT
High tech long-term health monitoring systems
Performance-based durability design
New Repair Materials and Systems
Durability of repair systems
Smart materials and systems
Field Process Technologies
Improved Management Systems for Existing Infrastructure

37. Ultra-high Strength Concrete
Unique combination of properties
Superior strengths
Good ductility
Good durability
Lighter and durability structures
Requiring less raw materials
Requiring less energy
Generating fewer CO2 emissions

38. Nanotechnology in Concrete
Nano-catalysts to reduce clinkering temperature in cement production
Silicon dioxide nano-particles (nanosilica) for ultra-high strength concrete
Incorporation of carbon nano-tubes into cement matrix would result in stronger, ductile, more energy absorbing concrete
Eco-binders (MgO, geopolymers, etc) modified by nano-particles with substantially reduced volume of portland cement

39. Government’s Sustainable Development Policy for Infrastructure
Taiwan Public Construction Commission prepared and the Executive Yuan approved a white paper and action plan on “Sustainable Public Infrastructure - Energy Saving and Carbon Reduction” in November 2008
The SD policy for infrastructure is being implemented in Taiwan

40. Conclusions
We, the concrete industry, need to adopt the following sustainable concrete technology to meet the infrastructure needs and protect the environment
Use more supplementary cementing materials
Recycle and reuse of concrete
Use life-cycle cost approach to seek better and durable concrete structures
Research and use of emerging technologies (e.g., repair and rehabilitation technology to extend service life of infrastructure)

41. Thank You!