The application of geopolymers has recently been given significant attention to address climate change and the growing scarcity of construction materials in the 21st century. Researchers have utilized industrial waste or supplementary cementitious materials containing high levels of silica and alumina as precursors along with different alkaline activators. Furthermore, the technical challenges associated with waste brick management or recycling include both land use changes and financial implications. The existence of amorphous aluminosilicates in waste clay bricks, which can be used as geopolymer binders, has drawn attention recently. This paper reviews the recent advancements of the integration of clay brick wastes in geopolymer applications, individually as well as its use with other alternative materials. Prior studies suggest that waste clay bricks can effectively serve as the primary source material in geopolymer applications. This review covers various aspects, including the assessment of fresh, mechanical, microstructure, and durability-related properties. It specifically focused on enhancing these properties of waste clay bricks through mechanical and thermal treatments, through varying curing conditions, utilizing different types of alkaline activators, and considering their properties and corresponding ratios in the development of geopolymer products using waste brick powder. Furthermore, this paper portrays a critical review of the sustainability implications of the utilization of clay brick waste in geopolymer applications. Conclusively, this review provided the lessons learnt, research gaps, and the future direction for investigation into the feasibility of geopolymers derived from waste clay brick powder.

The global focus on geopolymer binder production has increased due to the adoption of waste materials and industrial byproducts. Given the gradual decline of the availability of fly ash and ground granular blast furnace slag (GGBFS) resulting from the decarbonization process in electricity and steel productions, waste clay brick powder (WCBP), could be a viable substitute of these pozzolanic by-products. This research is dedicated to thoroughly investigate the techno-eco-efficiency performance of WCBP when utilized as a geopolymer precursor. The favorable mechanical characteristics exhibited by fly ash-GGBFS-WCBP-based geopolymer binder emphasize the importance of assessing its sustainability alongside its technical viability. The study employed life cycle analysis (LCA), following ISO 14040-44 standards, and using the Simapro software, to evaluate the environmental implications of the use of WCBP-based geopolymer mixtures. Human toxicity emerged as the primary impact. Moreover, the analysis of life cycle costs highlighted key financial factors, with around 65-70% attributed to alkaline activators of the total cost. The production of alkaline activators was identified as a critical point for both environmental impact and economic considerations due to energy consumption. While WCBP-rich samples exhibit a 1.7-0.7% higher environmental impact compared to the control mix (CM), their high mechanical strength and cost-effectiveness make them technologically and economically efficient geopolymer mixes. In conclusion, the portfolio analysis for techno-eco-efficiency affirms that mixes containing 40%, 30%, and 20% WCBP are more efficient than those using 10% and 0% WCBP, respectively.

This paper evaluates the feasibility of using WCBP as a partial alternative for fly ash in geopolymer mortars with GGBFS, under ambient and heat curing conditions. The physical, mechanical, and mineralogical properties of geopolymer mortar with 10 to 40% WCBP were investigated. Microstructural properties of WCBP and geopolymer mortars were investigated using XRF, XRD, TIMA, SEM and EDS. Reductions of the flow of fresh mortar were observed with the increase of WCBP. The highest 28 days compressive strengths were obtained in the mortars containing 40% WCBP, both at ambient and heat curing conditions. Microstructural analysis highlighted compact structure and reduced porosity, attributed to WCBP's role in enhancing fly ash-GGBFS mortar and fostering geopolymer gel formation.

The high carbon emissions and environmental impact associated with ordinary Portland cement have driven the search for sustainable alternative binders. In this context, waste clay brick powder, generated in large quantities from construction and demolition waste, offers a promising aluminosilicate source for geopolymer production. This study investigates the long-term durability performance of geopolymer mortars incorporating waste clay brick powder in terms of resistance to aggressive sulphate exposure, highlighting the potential of waste clay brick powder geopolymer as a potential sustainable building material. Mortars with 0-60% waste clay brick powder content were immersed in 5% Na₂SO₄ solution for up to 180 days to assess the chemical resistance, dimensional stability, and mechanical performance. Microstructural and phase analyses using X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy revealed a cohesive matrix with limited microcracking and minimal sulphur ingress, indicating strong chemical and structural stability. Moderate waste clay brick powder incorporation enhanced matrix durability, with compressive strength peaking at approximately 69 MPa after 180 days, compared to 63 MPa for the control with a decline in strength at higher waste clay brick powder contents. After 180 days of sulphate exposure, compressive strength reduction ranged from 10 to 19% across all mixes. Mixture W40 showed the lowest expansion of 0.0516%, compared to 0.0632% in the control and 0.0757% in W60. The mass gain was 1.91% for mix W40 compared to 2.8% for the control, indicating reduced susceptibility to sulphate ingress. These results indicate the potential of waste clay brick powder as a sustainable binder for durable building materials, contributing to enhanced performance in aggressive environments.