Effect of Na2O content, SiO2/Na2O molar ratio, and curing conditions on the compressive strength of FA-based geopolymer

In the work, compressive strength in FA (Fly Ash)-based geopolymer is evaluated considering four test variables covering Na2O content, SiO2/Na2O molar ratios, curing temperature/period, and pre-curing temperature/period. The results reveal that higher compressive strength can be obtained with higher Na2O content, higher curing temperatures, and longer pre-curing periods at the relatively low temperature (23 °C). On the other hand, an extension of curing period at high temperatures leads to strength reduction due to increasing macro-pores over 50 nm. Through the various tests, strength grade contours considering SiO2/Na2O molar ratios, Na2O content, and curing temperatures are obtained, which can be utilized for an effective mix design for FA-based geopolymer.