Effect of polyether shrinkage reducing admixture on the drying shrinkage properties of alkali-activated slag

Abstract

The effects of a shrinkage-reducing admixture (SRA) on the hydration, mechanical properties, drying shrinkage, weight loss, and microstructure of alkali-activated slag (AAS) were investigated in this paper. The results show that adding SRA in a certain range (≤2%) can make the exothermic peak move forward and increase the exothermic heat of hydration. The mechanical properties of AAS deteriorated as the SRA content increases. The addition of SRA had no effect on the type of hydration products, but the amount of hydration production decreased as the SRA content increases. The volume of the pore of AAS slurry containing SRA also decreased, while the pore size became larger, which was strongly related to drying shrinkage. Our results support the contention that the mechanism by which SRA reduces drying shrinkage is mainly related to the decrease of surface tension, the generation of fewer pores, and the coarsening of the pore structure.