THE EFFECT OF LIMESTONE POWDER ADDITION ON STRENGTH OF SLAG BLENDED CEMENT

reduce CO2 emission as well. The fine limestone powder may accelerate the early hydration of cement clinkers by providing extra nucleation sites; Furthermore, inert limestone filler can further influence the later compressive strength due to two different effects, the dilution effect (strength reduction) and the filler effect (better packing of the powder; strength increase). In this study, the content of blast-furnace slag in a slag blended cement (cement:slag=0.3:0.7, by mass) is reduced from 70% to 60% by the replacement of 10% limestone powder, aiming to make a ternary blended cement to further reduce CO2 emission. The compressive strength of mortar (cement:slag:limestone:water:sand = 0.3:0.6:0.1:0.5:3, by mass) tested according to European Standard EN 196-1:2005 shows that the addition of limestone filler increases the compressive strength of ternary blended cement from 1 up to 180 days. Investigation indicates that the positive effect of limestone addition on compressive strength is caused by the increased hydration of Portland cement on the one hand, and the hindered transformation of ettringite to monosulphate in the presence of limestone on the other. The result may give us more information to produce even greener cementitious materials using limestone filler.