Strength development and acid resistance of geopolymer based on waste clay brick powder and phosphorous slag

This study aims to investigate the strength development and durability of geopolymer mortars based on waste clay brick powder (WCBP) and phosphorus slag exposed to acid attack. WCBP was partially replaced with slag (8, 16, and 24 wt%) and resulting blends were activated by an aqueous solution of NaOH and sodium silicate with different SiO 2 /Na 2 O ratios (M S ) and Na 2 O concentrations. The optimized geopolymer mortar specimens were also immersed in sulfuric and hydrochloric acid solutions of pH = 1 for 6 months to assess changes in their physical and structural properties. The results were compared with those of Portland cement and high alumina cement mortars as control specimens. The key durability parameters measured were the evaluation of mass change, compressive strength loss, and deteriorated depth. Complementary studies were also carried out using X‐ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy in line with energy dispersive X‐ray techniques to quantify the compositional and microstructural changes. The results demonstrate a potential of value‐added reuse application for WCBP by adding a suitable amount of slag. The findings also showed that geopolymer mortars were less susceptible to acid attack than the control mortars; however, superior enhancement in durability properties was not achieved.