Portland Blast-Furnace Slag Cement

a cement produced by grinding portland cement clinker together with pellets of blast-furnace slag (30–60 percent of the total weight) and a small amount of gypsum. It differs from ordinary portland cement by a slower increase in strength in the initial hardening period and an increased water resistance. It is used mainly for man ufacturing precast reinforced-concrete structures and items prepared with steam curing as well as for laying concrete in hydraulic engineering installations.