Impacts of different activators on the strength properties of SCM-Ⅰ furnace slag based cementing materials

With the cementing materials based on furnace slag used as main raw material, this study analyzed the effects of different kinds of activators on SCM-Ⅰ cementing materialsbased on furnace slag. The analysis of SEM and XRD, and perspectives of microscopic and hydration products were added to the study. The results show that alkali-activators like Ca(OH)₂, NaOH have certain activation effect. The addition of Ca(OH)₂ has increased the 28 d compressive strength of cementing materials by 34.77 %. Na₂SiO₃ has inhibitory effect on the strength when the mixing amount is 0.75 % and the strength has depressed by 45.15 %. The compressive strength increases 7.90 % when 0.50 % of Na₂SO4 is added, which shows that the activation effect is insignificant. When 1.00 % of the mixing amount of chloride activators such as NaCl and CaCl₂ is added, the compressive strength increasesby 68.08 % and 5.62 % respectively. CaCl₂ promotes the hydration reaction and a lot of ettringite is formed. The addition of Na₂SiO₃ inhibits the formation of C-S-H gels, which declines the strength of the cementing materials