The effect of hot steam curing on the compressive strength and flexural strength of geopolymer concrete

Abstract

This research was conducted to determine the effect of hot steam curing on the compressive and flexural strength of geopolymer concrete with variations of NaOH molarity. The specimens used in this study are cylinders with a size of 150 mm  300 mm for the compressive strength test and beams with dimensions 150 mm 150 mm  600 mm for the flexural compressive strength test. The specimens were cured at 80℃, 90℃, and 100℃ for 2 and 3 hours. Curing at room temperature was carried out after the hot steam curing process finished. The compressive and flexural strength tests were carried out when the specimens reached 28 days old. The result of the study showed that the 14 M mixture had greater compressive strength and flexural strength than 10 M. By increasing the temperature every 10℃ and the duration of the hot steam curing for 1 hour, the compressive strength increased by an average of 5.97% and 3.07% and the flexural tensile strength by an average of 19.73% and 7.34%, respectively. Besides that, it can be proposed a multiple regression equation for compressive strength, namely f’c = 21,728 + 0,147x1 + 1,040x2 + 0,162x3 and multiple regression equation for tensile strength are fr = -2,270 + 0,061x1 + 0,318x2 + 0,029x3. Where f’c is compressive strength, and fr is flexural tensile strength, while x1, x2, and x3 are temperature, curing time, and molarity of NaOH.