Ground Granulated Blast Furnace Slag (GGBS) and Rice Husk Ash (RHA) Uses in the Production of Geopolymer Concrete

Abstract

Research for complete OPC free concrete is still evolving and there is a need for developing alternative binding agents which are environmentally friendly. One such alternative is identified to be geopolymer which often consists of fly ash, sodium silicate, and sodium or potassium hydroxide (NaOH or KOH). Since, many coal based power plants in US have been retiring due to thrust towards cleaner energy production and this may lead to scarcity of flyash in future. Hence the objective of this study is to incorporate other Pozzolanic materials in geopolymer concrete. In line with objective two Pozzolanic materials granulated blast furnace slag (GGBS) and rice husk ash (RHA) were used to replace flyash in geopolymer concrete. Tests are performed on compressive strength of geopolymer concrete by varying percentages of RHA and GGBS. Results indicated that complete replacement of flyash in geololymer concrete with RHA and GGBS is not feasible. As geopolymerization needs specific amount alumina, RHA and GGBS have minimal amount which is adversely affecting the strength. Nevertheless GGBS up to 50% can be used as replacement of flyash to attain compressive strength around 2000 psi and 5-10% of RHA can be used to achieve similar strength. In addition micro-characterization of geopolymers was performed using scanning electron microscope and X-ray diffraction. These techniques helped in understanding the characteristics of binder formation around the sand particles which is affecting the strength.