Abstract
This study addresses the environmental concerns associated with the disposal of red mud (RM) and Waste Foundry Sand (WFS). It explores the use of these industrial by-products, along with silica fume, fly ash, and Desur clay, to produce geopolymer clay bricks as a sustainable alternative to traditional clay bricks. Initially, 5M geopolymeric clay bricks were produced by partially substituting natural clay with RM, fly ash, WFS, sodium silicate, and caustic. The highest compressive strength achieved was 3.27 N.mm- ² with a 5M caustic concentration. To further optimize the raw materials and enhance the strength, WFS was partially replaced with different percentages of silica fume. Grey Relational Analysis (GRA) was used to identify the most effective mix, transforming multiple objectives into a single optimal solution. Nine mix designs were developed following the Taguchi L9 orthogonal array. The optimum mix demonstrated a compressive strength of 5.02 N.mm- ², comprising 13.75% red mud, 10% silica fume, 12.85% WFS, 33.43% Desur clay, and 30% fly ash. Water absorption remained within allowable limits across all samples. Variance analysis indicated that silica fume (47.45%) was the most influential factor, followed by red mud (30.36%), while WFS contributed the least (21.17%). Microstructural and mineralogical analyses using SEM, FTIR, and XRD confirmed the formation of geopolymeric gels and stable phases. Heavy metal assessments via ICP verified that the bricks are environmentally safe for utilization.