Effects of activator properties and GGBFS/FA ratio on the structural build-up and rheology of AAC

Abstract

The effects of ground granulated blast furnace slag/fly ash (GGBFS/FA) ratio, mass ratio of SiO2 to Na2O (M s ) of activator solution and sodium silicate dosage on structural build-up, flow properties and setting characteristics of alkali-activated cement (AAC) mixtures were investigated. The solid-like behavior becomes more dominant with increasing GGBFS/FA ratio. M, value had significant effect on the structural build-up. Significantly higher initial storage modulus with a low increasing rate was observed for the M, values lower than 0.8. However, for higher M, values, a sudden increase in storage modulus was observed after negligible initial structuration. An increase in sodium silicate dosage caused a considerable delay in the abrupt increase in the structural formation. It was observed that flow curves of AAC fit the Herschel-Bulkley model with shear-thickening behavior. ICP-OES tests revealed the lower release of aluminum and calcium into the pore solution of GGBFS/FA mixtures with low M, values.