Supplementary Cementing Materials

Supplementary Cementing Materials

Fly ash and ground slag reduce the heat build up in concrete because their heat of hydration is lower than Portland cement. Ground granulated blast furnace slag, fly ash and natural pozzolans slow the setting time in concrete. Concrete with Portland cement and supplementary cementing materials can take longer to cure and gain strength than concrete with Portland cement alone. Supplementary cementing materials improve concrete finish ability. Silica fume is good at increasing concrete pump ability. Silica fume may color concrete blue or dark grey, and fly ash may give it a tan color. Ground granulated blast furnace slag and fly ash help increase the strength of concrete and reduce permeability. Silica fume also reduces permeability. Slag, fly ash and silica fume improve concrete resistance to sulphate corrosion. Fly ash and silica fume provide corrosion protection to steel embedded in concrete.