Experimental Study of Using Rice Husk Ash and Borax on The Compressive Strength of Geopolymer Concrete

The development of infrastructure in Indonesia is currently very increasing, The use of concrete is widely used to build dams, buildings, roads, bridges and others. Concrete is used because it has advantages over other materials, apart from having compressive strength, concrete is also a relatively inexpensive material. However, the increasing amount of cement used in the manufacture of concrete will cause an increase in global warming. Thus, geopolymer concrete was introduced as an alternative to reduce cement consumption in concrete work. The purpose of this study was to determine the effect of using rice husk ash and borax as an alternative material on the compressive strength of concrete and to determine the effect of using rice husk ash and borax as an alternative material to slow the setting time of geopolymer concrete. The variations in the use of rice husk ash 0%, 10%, 15%, and 20% with the use of 3% borax. From the results of the study, the use of rice husk ash and borax in the geopolymer concrete mixture had an effect on the compressive strength of concrete in this study, with the addition of rice husk ash there was a decrease in compressive strength when compared to normal geopolymer concrete or without a mixture of rice husk ash and borax. The use of 15% rice husk ash and 3% borax achieved the highest compressive strength values when compared to the use of rice husk ash as much as 10% and 20%. Furthermore, the more the use of rice husk ash with the use of 3% borax, the longer the setting time in geopolymer concrete.