Influence of Aggressive Environment in Macro and Microstructural Properties of Bottom Ash Geopolymer Concrete

Abstract

India generates 759.02 million metric tons of coal ash annually. Part of that quantity is successfully utilized, and the remaining portion of the ash is discarded into a landfill. There also is a need to address pollution. Cement industries are responsible for 7% of global warming. Cement has been replaced entirely by thermal power plant waste, and bottom ash is used as a binder to overcome those issues. A few researchers have carried out strength characterization, but an extensive study needs to be carried out under different environmental exposures. Therefore, the present study investigated macro and micro properties of bottom ash geopolymer concrete (BAGPC) subjected to aggressive ecological exposure conditions such as acid, salt, and sulfate attack. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) of eight molarities were used as activators for the bottom ash geopolymer concrete (BAGPC) binder. Further bonding between steel and conventional concrete BAGPC mixes was investigated. The durability of conventional concrete (CC) was taken as the control mix to compare the durability of the optimized mix (B4) of bottom ash geopolymer. The test samples were cured for 28 days under ambient temperature and tested for the effect of MgSO4, NaCl, and HCl. The strength loss and weight loss of the BAGPC B4 mix after 7, 28, 56, 90, and 180 days under aggressive conditions showed better performance than CC. It has been observed that geopolymer concrete has good bonding in nature, and the bond strength results indicate excellent bonding between steel and concrete. Microstructure studies revealed that the BAGPC B4 mix had a strong microstructure and not as much of a porous structure. It is concluded that BAGPC has potential value in the construction industry based on all aspects of the experiment.