Effective function of activated bagasse ash for high early strength geopolymer

Abstract

High early-strength concrete and geopolymer offer advantages of faster construction and require less curing time than traditional concrete. Bagasse ash (BA), an inert pozzolan with low reactivity in alkaline media, was activated with 10M NaOH to enhance its porosity and surface area. It was then incorporated into an 80:20 wt% mixture of metakaolin (MK) and BA to improve the early-strength properties of geopolymers. This study investigates the effects of varying amounts of activated bagasse ash (ABA) on the physical and mechanical properties of a binary MK-BA-based geopolymer. The pozzolan-to-alkali ratio was maintained at 1:1, with a difference of 10M NaOH-to-Na₂SiO₃. The results indicated that the compressive strength of formulation with 50 wt% ABA increased by approximately 33% compared with formulation without ABA. XRD analysis showed a sodium aluminum silicate peak at 3 days, which decreased after 28 days, confirmed by SEM/EDS. The transformation of sodium aluminosilicate gel into a dense geopolymer matrix was observed, with IR spectra demonstrating the presence of Si–O-(Si/Al) bonds contributing to high compressive strength formulations. Overall, the ABA led to the early formation of the geopolymer 3D network with high compressive strength values.