Activation of Slag as Partial Replacement of Cement Mortar: Effects of Superfine GGBS, Temperature, and Admixture

Abstract

With perspective to the precast industry, this paper is a study of superfine (SF) ground granulated blast-furnace slag (GGBS) as replacement (0%, 30%, 50%, and 70%) of rapid-hardening cement (CEM 1 42.5R) under two types of activation, namely discrete temperature activation (20°C–35°C for 16 h) and two accelerating admixtures. The thermal activation is found to provide the larger improvements in early-age strength as against use of the admixtures; however, the combined effect achieves measurably better performance at early age. Also, the novel admixture, designed to activate SFGGBS, is found to deliver definitive strength enhancement at both (low and moderate) temperature conditions during early ages. Further, the 28-day strength of mortars remains unaffected and is marginally improved under the combined effect of SFGGBS, the novel admixture, and temperature activation.