Properties of one-part CaO–Na2CO3 activated ground granulated blast furnace slag

Abstract

In this study, the fresh and hardened performance and durability of one-part ground granulated blast furnace slags (GGBFS) activated by solid CaO and Na2CO3 were discussed, and their hydration process and microstructure development were analyzed accordingly. Results showed that when the water-to-binder ratio was 0.32, the alkali-activated slag (AAS) paste exhibited lower flowability, higher yield stress and plastic viscosity. As the content of CaO and Na2CO3 increased, the yield stress, plastic viscosity, and compressive strength of AAS after hardening all increased. For the durability of the hardened sample, AAS with high content of activator have higher shrinkage strain and chloride ion flux. The microscopic analysis results indicated that AAS containing CaO and Na2CO3 exhibited more intense hydration heat release and rapid microstructure development in the early stage, thereby promoting the improvement of strength. The use of CaO and Na2CO3 to activate GGBFS has enormous application potential in solid waste utilization and carbon emission reduction, which can reasonably replace traditional Portland cement (PC) as a new generation of sustainable cementitious materials.