China Vacation

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

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Low Material Cost Low Construction Cost Low
Maintenance Cost Good Durability
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(No Transcript)
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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

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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

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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

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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

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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

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Reduce Environmental Impacts of Cement Production
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Asias Increasing Share of Consumption of Cement
From Prof. Ouchi
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Consumption of Cement in Asian Regions
From Prof. Ouchi
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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

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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?

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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.

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Greater Use of Supplementary Cementing Materials
(SCM)
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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

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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

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High-Performance, High-Volume Fly Ash Concrete

• Fly ash replacement gt50
• Low water content lt130 kg/m3
• Cement content lt200 kg/m3
• W/CM 0.30 or less
• Use HRWRA
• Excellent long-term mechanical and durability
  properties

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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)

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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

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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

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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

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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
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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
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Recycle and Reuse of Concrete
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Construction Demolition (CD) Waste

• 1 billion tons of CD waste (broken concrete,
  bricks, and stone) are generated annually
  worldwide
• 10 million tons of CD waste generated annually
  in Taiwan

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Use of Construction Demolition (CD) 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

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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

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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

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Enhancement of Service Life
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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

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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
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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
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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

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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

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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

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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

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Governments 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

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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)

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Thank You!