Evaluation of strength and durability of fly ash-lime-quarry dust bricks

This investigation explores the optimization of fly ash utilization in brick production by integrating lime, gypsum, and quarry dust in varying proportions to develop Fly Ash-Lime-Gypsum-Quarry Dust Bricks (FLGQB) with dimensions of 230 mm × 110 mm × 90 mm. While prior studies have examined fly ash-based bricks, they often overlook the nuanced interplay of quarry dust content and curing duration on mechanical properties, particularly beyond the conventional 28-day period. This study addresses this gap by systematically evaluating compressive strength, split tensile strength, water absorption, density, and initial rate of absorption across 13 mix proportions, with a focus on extended curing up to 56 days. The Mix 9 (M9) composition—35% fly ash, 10% lime, 25% gypsum, and 30% quarry dust—emerged as optimal, exhibiting a 56th-day compressive strength of 12 MPa, surpassing many traditional and alternative bricks. Unique to this work, regression-based prediction models were developed to correlate mix proportions and curing age with strength parameters, achieving over 92% accuracy when validated against experimental and existing data. These models offer a practical tool for predicting long-term performance, addressing a limitation in earlier research that often relied on empirical observations alone. By demonstrating the critical role of quarry dust as a filler and its influence on void reduction, this study advances the understanding of compositional control in sustainable brick design, providing a robust alternative to conventional clay bricks.