Transport properties of fly ash-slag-based geopolymer concrete with 2M sodium hydroxide combined with variations in slag percentage, Al/Bi ratio, and SS/SH ratio

Abstract

The aim of this research is to determine the effect of sodium hydroxide molarity 2M combined with variations in slag percentage, ratio of alkali activator to binder (Al/Bi), and ratio of sodium silicate to sodium hydroxide (SS/SH) on the transport properties of fly ash-slag-based GPC cured at ambient temperature. The result is increase in slag percentage and SS/SH ratio lead to a decrease in porosity, water absorption rate and chloride permeability. The alkali activator to binder (Al/Bi) ratio of 0.45 produces the lowest porosity, water absorption rate, and chloride permeability. The porosity, sorptivity, and chloride penetration depths of all GPC are lower than those of OPC. The recommended mix compositions for GPC that exhibit lower transport properties than OPC are GPC4 (slag 40%, SS/SH ratio 1.5, Al/Bi ratio 0.45); GPC5 (slag 50%, SS/SH ratio 1.5, Al/Bi ratio 0.45); and GPC7 (slag 30%, SS/SH ratio 2.0, Al/Bi ratio 0.45).