The Use of Rice Husk Ash in Enhancing the Material Properties of Fly Ash-Based Self Compacted Geopolymer Concrete

Concrete is a material that is needed for building construction or others is increasing. Construction increased as cement use increased. The continued use of cement will cause environmental damage, cement is the 8th largest source of carbon gas emissions in the world. One of the revolutionary developments using environmentally friendly materials as a substitute for cement is geopolymer concrete. Alternative materials rich in silica and alumina for the manufacture of geopolymer concrete, namely adding rice husk ash (RHA), fly ash, silica fume, glass powder, as substitute for cement. A cement substitute can use RHA as partial substitute for geopolymer concrete based on fly ash, which is rich in silica and alumina. For the binder, an activator is needed, the activator itself usually uses NaOH and Na2SiO3. The purpose of this study was to determine the effect of rice husk ash as a partial substitution of fly ash on split tensile strength and porosity of geopolymer concrete and determine the optimum percentage of use of RHA to produce tensile strength and porosity in geopolymer concrete with material calculations using EFNARC 2005. Geopolymer concrete which binders using 14M NaOH and Na2SiO3, and binders namely Fly ash and rice husk ash, with variations for RHA 0%, 5%, 10%, 15%. Sample in the form of cylinder with diameter of 150 mm and height of 300 mm for tensile strength and cylinder with diameter of 2 inches and height of 5 mm for porosity. The specimens were treated for 28 days with room temperature curing. From the data obtained, it can be concluded that there is an effect of RHA to increase tensile strength and reduce porosity in geopolymer concrete with an optimum variation of 10%, with an optimum tensile strength of 1.061 MPa, and minimum porosity of 13.13%.