23-02-2011, 10:32 AM
presented by:
Abdulrahman Albedah.
Ali Al-theeb
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Supplementary Cementitious Materials
Types of SCMs
• Natural (ASTM C 618 Class N)
• Produced from natural mineral deposits (e.g., volcanic ash)
• May require heat treatment (e.g., metakaolin)
• Processed / Manufactured
• Silica fume (ASTM C 1240)
• Slag (ASTM C 989)
• Fly Ash (ASTM C 215)
Benefits of SCMs
• Industrial by-products (waste utilization)
• Typically cheaper than cement (except for silica fume and metakaolin)
• Environmentally conscious
• No CO2 emission during processing
• Less landfill waste
Influence of SCMs
Concrete Fresh State
• Heat of Hydration
• Water demand
• Workability
• Bleeding
• Setting time
Concrete Hardened State
• Mechanical properties
• Durability
Hydraulic vs. Pozzolanic Reaction (1)
• Latent Hydraulic Reactions:
Chemical reaction with water that leads to setting and hardening of the material.
• Pozzolanic Reactions:
Chemical reaction with calcium hydroxide (lime) and water that leads to the formation of cementitious products.
SCM Chemical Composition
Basic Cement Hydration
SCM Reactions
Fly Ash
• The most widely used SCM.
• Inorganic by-product of powdered coal after burning in power plants.
• Approximately ½ the cost of cement
• 10 % to 30 % limit on cement replacement.