SUSTAINABLE CONCRETE TECHNOLOGY –CHALLENGE AND OPPORTUNITY

Dr. Tony C. Liu Dr. Jenn-Chuan Chern Visiting Research Fellow Distinguished Professor

National Taiwan University, Taiwan, ROC

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

Low Material CostLow Construction CostLow Maintenance CostGood Durability

Worldwide Concrete Production

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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

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

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

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

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

Reduce Environmental Impacts of Cement Production

Asia’s Increasing Share of Consumption of Cement

From Prof. Ouchi

Consumption of Cement in Asian Regions

From Prof. Ouchi

Use of Cement, Slag, and Fly Ash in Taiwan (2007)

• Cement – 13.5 million tons

• GGBF Slag – 5 million tons– Usage Rate: 100%

• Fly Ash– 4 million tons– Usage Rate: 70%

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?

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.

Greater Use of Supplementary Cementing Materials (SCM)

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

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

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

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)

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

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

Silica Fume

• 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

20,000 x

Condenses fromfurnace gases

Applications of SF Concrete

• Property-enhancing applications– Ultra High Strength

Requirements– High Abrasion

Resistance– Early-Age Strength

Improvement– Corrosion Protection

• Repair applications1600 m3 of silica fume concrete was placed in 1983

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

Recycle and Reuse of Concrete

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

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

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

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

Enhancement of Service Life

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+

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

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

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

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

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

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

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

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)

Thank You!