This Information Paper provides an introduction for engineers and specifiers to the industrial by-product silica fume and its use as a supplement to CEM I Portland cement, to produce and place high performance durable concretes. Silica fume can give significant benefits to concrete including reduced construction times, improved pumpability, enhanced early strength development and excellent durability, particularly resistance to abrasion, impact and chemical attack. The improvements in properties of the fresh and hardened concrete and the high levels of strength and durability that can be achieved are described, and illustrated by recent case studies.

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Pages: 12

Contents
• What is silica fume?
• Uses and benefits of SF in concrete
• - Track record of SF in concrete
• - Standards and specifications
• Practical considerations
• - Approaches to mix design
• - Batching and mixing
• - Placing and pumpability
• - Curing
• - Hardened concrete properties
• - Compressive and tensile strength
• - Performance and durability data for concrete
• - Abrasion and impact resistance
• - Chemical resistance
• - Resistance to freeze/thaw
• - Suppression of alkali-silica reaction
• - Permeability and protection of reinforcement
• - Chloride ingress
• - High strength/performance concretes
• - Marine concretes
• Environmental aspects associated with use of SF in concrete
• - Embodied environmental impact and carbon footprint
• Economics
• Key features of SF in concrete
• Conclusions
• References
• Further reading and sources of information
• Case studies: Suspended slab. Slab for railway ballast transfer. Concrete base placed underwater. Hardstanding for military use. Coastal defence scheme. Hardstanding for milk tankers. Waste transfer station.