Geopolymers with High Ash Percentages: A Stability Study

Wood ash (WA) is the fine residue left behind after wood combustion. Currently, only a fraction of wood ash undergoes recycling, with the majority being disposed of in landfills. Enhancing wood ash recycling can mitigate environmental harm, reduce transportation expenses, and minimize waste disposal. This study aims to investigate the stability of a geopolymer incorporating 30% wood ash as a filler material. The ashes, sourced from beech wood, are sieved and mixed with a metakaolin-based geopolymer matrix. The samples, cured at room temperature (25 °C) for 24 h, are evaluated through integrity tests, mass loss evaluation, FT-IR, and SEM analyses. The results of the integrity test and mass loss evaluation confirmed the stability of the geopolymers in water, with a mass loss of less than 1% after 56 days. The FT-IR peak analysis confirmed the occurrence of geo-polymerization and the incorporation of the ashes into the geopolymer paste. Finally, the SEM results showed the uniform surface of the samples and the good distribution of the ashes within the geopolymer network.