Effect of elevated temperature curing on properties of alkali-activated slag concrete

This investigation is focused on the effect of curing temperature on microstructure, shrinkage, and compressive strength of alkali-activated slag (AAS) concrete. Concrete prepared using sodium silicate and sodium hydroxide as the activator had greater early and flexural strength than ordinary Portland cement concrete of the same water/binder ratio, but it also had high autogenous and drying shrinkage. Heat treatment was found to be very effective in reducing drying shrinkage of AAS concrete and promoting high early strength. However, strength of AAS concrete at later ages was reduced. Microstructural study revealed an inhomogeneity in distribution of hydration product in AAS concrete that can be a cause of strength reduction. Pretreatment at room temperature before elevated temperature curing further improved early strength and considerably decreased shrinkage in AAS concrete. (C) 1999 Elsevier Science Ltd. All rights reserved.