Durability of Alkali-Activated Fly Ash/Slag Concrete

This study investigated the durability of alkali-activated binders based on blends of fly ash (FA) and ground granulated blast furnace slag (GGBFS). Five fly ash-to-slag ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 by mass were selected to produce alkali-activated fly ash/slag (AAFS) concrete. Sodium oxide (Na2O) concentrations of 6% and 8% of binder weight and activator modulus ratios (mass ratio of SiO2 to Na2O) of 0.8, 1.0, and 1.23 were used as alkaline activators. Test results show that the total charge passed of AAFS concrete is between 2500 and 4000 coulombs, higher than the comparable OPC concrete. However, AAFS concrete exposed to sulfate attack performed better than OPC concrete. Based on the results, 100% slag-based AAFS concrete with Na2O concentration of 8% and activator modulus ratio of 1.23 has the superior performances.