The Effect of Natural Retarder On Fly Ash Based Geopolymer Concrete

Environmental issues resulted from cement production have brought world’s concern into a novel concrete technology that is more environmentally friendly. The introduction of geopolymer as an alternative binder to cement is a grand inspiration to many researchers to develop a new technology in concrete industry. The current limitation of geopolymer concrete that can only be applied in precast concrete industry has initiated this research to be conducted with cast in situ requirements. Commercial admixture that is usually applied in previous geopolymer concrete researches was replaced with glucose as natural retarder to delay the setting time of fresh geopolymer concrete. The curing methods, namely hot gunny, ambient, and external exposure curing were proposed to adjust with the condition of cast in situ environment. Compressive strength results show that the inclusion of glucose as natural retarder could improve the concrete performance, while external exposure curing provided the most optimum condition to the geopolymer concrete strength.