Gradation and Characterisation of Geopolymer Concrete at Ambient Temperature

Abstract

For decades, ordinary cement has reigned supreme as the binding agent in concrete production. However, its manufacturing process has emerged as a major contributor in CO2 emissions. Developing countries face a significant hurdle in managing industrial waste. In recognition of these challenges, researchers have devoted the past several decades to exploring innovative and sustainable alternative materials. Environmental concerns and a desire for improved performance are driving interest in geopolymer concrete as a viable alternative to traditional concrete. Researchers have extensively explored the use of diversely sourced materials, such as fly ash (FA), ground granulated blast-furnace slag (GGBS), metakaolin, rice husk ash, silica fume, etc., in developing geopolymer composites. Despite high potential, the geopolymer concrete faces several hurdles before widespread adoption, such as inconsistent source materials, heat curing limitations, lack of optimized mix design and durability data. This research addresses the difficulties faced in producing geopolymer composites. This study investigated geopolymer mortars (GPM) and geopolymer concretes (GPC) by examining how various control factors affect their durability, microstructure and mechanical properties in the fresh and mature stages. Source material include, binders in form of FA and GGBS, natural fine and coarse aggregate and alkali activator in form of silicate and hydroxide of sodium (NS,NH). Sulphuric acid (H2SO4), magnesium sulphate (MgSO4) and sodium chloride (NaCl) solution were used to recreate harsh chemical environment to gauge resistance offered. Sorptivity, Rapid-chloride penetration testing and carbonation tests were performed to analyse the durability behaviour of GPC. Following these tests, the specimens were subjected to microstructural analysis using different tools such as scanning electron microscopy (SEM), energy-dispersive x-ray (EDS), X-ray diffraction (XRD) and fourier transform infra-red spectroscopy (FTIR). In the GPM and GPC mix, the GGBS