Setting time and 7-day strength of geopolymer mortar with various binders

Concrete is considered one of the most vital materials used in construction all over the world which ordinary portland cement (OPC) is used as the binder to produce it. The harmful effect of OPC production on environment is well known. Therefore, geopolymer concrete is considered an important alternative material in construction field due to its acceptable mechanical and durability properties as well as being environmentally friendly product. The main objective of this study is to investigate setting time and 7-day properties of geopolymer mortar considering several parameters as curing temperature, sodium hydroxide solution molarity, alkaline solution to binder ratio and binder type. The evaluated properties in this study were setting time, 7- day compressive strength, 7- day flexural strength and microstructure of mortar specimens. Results indicated that binder type has a significant effect on the mentioned properties. Mixes contained 50% fly ash, 35% ground granulated slag (GGBS) and 15% silica fume yield the best properties. Also increasing curing temperature, sodium hydroxide solution molarity and decreasing alkaline solution to binder ratio improved mechanical properties of geopolymer mortar with various binders.