Effect of Chemical Activators on the Compressive Strength of Cement-Slag Mortar

Abstract

The reaction of ground granulated blast furnace slag (GGBFS) with water is slower compared to the hydration of ordinary Portland cement. This led researchers to concentrate on increasing the hydration rate of the GGBFS. Previous studies were done by (SCA) showed that GGBFS can be used with activators or a certain amount of Portland cement. Also, they found that alkali hydroxides and GGBFS can be reacted alone without any calcium hydroxide obtained from Portland cement hydration to obtain a strong cement paste in applications. This experimental study conducted by the TS EN 196-1 standard, with the ratio (79:21)% slag to cement and 0%, 1%, 2%, 3% and 4% levels of activators (CaCO3, Ca (OH) 2, Na2SO4, K2SO4 and CaSO4.2H2O); results indicates that with above ratio slag can be used with activator of (Na2SO4, K2SO4 and CaSO4.2H2O), greater compressive strength of 5-6 MPa was obtained at 2 and 7-day curing ages when K2SO4 was used as an activator at the dosages of 3% and 4%, while the activator (CaSO4.2H2O) can improve all ages, and there was not a clear difference among control mixture without activator and slag-mortars activated by CaCO3 and Ca (OH).