Canadian use of ground granulated blast-furnace slag as a supplementary cementing material for enhanced performance of concrete

The performance of concrete, in terms of its placeability, physical properties, and its durability, can be enhanced by the use of slag-blended cements or separately added ground granulated blast-furnace slag. It also has advantages for architectural purposes due to the whiteness it imparts to concrete. Properly proportioned and cured slag concretes will control deleterious alkali-silica reactions, impart sulphate resistance, greatly reduce chloride ingress, and reduce heat of hydration. Setting times and early age strengths can be controlled through appropriate proportioning, while later age properties are typically enhanced. CSA and ASTM standards cover both slag-blended cements (CSA A362; ASTM C595; ASTM C1157) and slag as a supplementary cementing material (CSA A23.5; ASTM C989). Since Lafarge introduced the first large-scale slag grinding plant near Hamilton in 1976, slag has become the predominant supplementary cementing material in Ontario. Recently, its availability in the U.S. has expanded dramatically.