Modelling of compressive stress-strain relationships of GPCC with fly ash blended with GGBFS

In total, 48 cylinders were tested to measure the uniaxial compressive stress-strain relationships of geopolymer concrete composite (GPCC) with fly ash blended with ground granulated blast-furnace slag (GGBFS). Four replica specimens were fabricated for each of the 12 combinations of three parameters: ratio of GGBFS to binder (0.2, 0.3 and 0.4), concentration of sodium hydroxide (8 and 12 M) and curing temperature (60 and 80 degrees C). The developed model incorporating functionalised parameters was able to closely predict the compressive stress-strain relationships of GPCC as observed in experiments, which were distinguished from those of Portland cement concrete by nearly proportional relationships between stresses and strains with the reduced modulus of elasticity (Ec) in the pre-peak region and the increased brittleness in the post-peak region. The predicted values of Ec by the developed equation were shown to be about 34 and 43% times less than those of Portland cement concrete on average, predicted by ACI building code and Eurocode 2, respectively.