The effect of heat-curing on transport properties of low-calcium fly ash-based geopolymer concrete

The aim of this study is to evaluate the transport properties of class F fly ash-based geopolymer concrete cured at various conditions. Twelve different heat curing regimes including three temperatures of 60, 75 and 90 °C and four curing durations of 8, 12, 18 and 24 h, as well as ambient curing, were imposed to the specimens. The material properties such as compressive strength, elastic modulus, ultrasonic pulse velocity, absorption, volume of permeable voids, pore size distribution and resistivity were evaluated against the reference Portland cement (OPC) concrete. Experiments showed that proper curing conditions such as curing at 75 °C for 18-24 h yield a geopolymer concrete with low volume of permeable voids and low sorptivity coefficient. The reduced volume of permeable voids and less continuous capillaries, attained by applying the proper curing regime, leads to an increased electrical resistivity and compressive strength of the low-calcium fly ash-based GPCs.