Stiffening rates of blended-cement pastes in hot climates

The influence of microsilica, ground granulated blast-furnace slag (ggbs) and a set-retarding superplasticiser on the setting of pastes at different curing temperatures was studied. The replacement level of ordinary Portland cement (OPC) by microsilica was 10%. Replacement levels of OPC by ggbs were 30, 50 and 70%. In addition to this, three different sources of ggbs from three countries were tested. Ambient temperatures of 25, 35 and 50°C were simulated. The results show that at 25°C, microsilica retarded setting only slightly whereas the ggbs and the set-retarding superplasticiser resulted in significant retardation. At the other two curing temperatures, the retardation effects of the ggbs and the superplasticiser diminished.