Development of a sustainable geopolymeric grout via mechanochemical activation with recycled brick powder

This research aims to address the limitations of conventional geopolymerization techniques in developing an environmentally friendly mechanochemically activated geopolymeric (MG) grout. The study primarily focuses on assessing the feasibility of using recycled waste brick powder (WBP) as a substitute for traditional industrial waste materials, such as ground granulated blast furnace slag (GGBS). A comparative analysis with the conventionally activated geopolymer (CG) grout was conducted to establish benchmarks for evaluating activation mechanisms. Key performance indicators, including mini-slump flow, setting time, unconfined compressive strength, density, and stress–strain behavior, were evaluated. Microstructural properties were analyzed using X-ray diffraction and scanning electron microscopy. Experimental results revealed that incorporating WBP as a partial replacement for GGBS significantly influenced both fresh and mechanical properties of the geopolymer grout. Substituting 15–45% of GGBS with WBP increased the slump flow of MG from 8.5 to 10 cm, reduced the final setting time from 235 to 90 min, and enhanced the compressive strength from 4.3 to 14 for 90 days, highlighting the potential of WBP as an effective supplementary material in sustainable grout formulations. The mechanochemical activation process further improved the performance, reducing the mini-slump flow by 10–27% and the final setting time by 9–25% and increasing the compressive strength by 7–30% compared to conventional activation methods. Microstructural analysis indicated that the pure WBP-based geopolymer grout exhibited a loose and fragmented morphology. However, the substitution of 15–45% GGBS for WBP resulted in more compact and homogeneous microstructures, with the MG grout showing greater density and compaction than CG. These findings demonstrate the efficacy of MGs incorporating WBP as a sustainable and high-performance alternative for grouting applications.