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Ground granulated blastfurnace slag

Ground granulated blastfurnace slag (GGBS) is the slag from iron producing blastfurnaces that is rapidly quenched in water and then ground into a powder. Chemically it is similar to, but less reactive than, Portland cement (PC).

When mixed with water it will hydrate in a similar way to Portland cement. It is always used in combination with Portland cement, typically in the range 35% to 70% GGBS, depending on the application.

The blends can be supplied as pre-blended factory produced cements, or can be formed in the mixer by adding Portland cement and GGBS each from its own silo.

Concretes containing GGBS/PC blends are slower reacting than pure PC concretes, but may have improved durability.

Acknowledgement: The Concrete Society

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