Production of Sustainable Paver Blocks from Metakaolin and Clayey Lateritic Sand

Abstract

Sustainable alternatives to significantly reduced CO₂ emissions and resource depletion associated with conventional concrete is in high demand in concrete production. In this backdrop, this study presents a production of sustainable paver blocks from metakaolin and clayey lateritic sand. The mechanical performance and statistical variability of this concrete paver blocks is achieved by partially replacing natural river sand with clayey lateritic sand and ordinary Portland cement (OPC) with metakaolin (MK), respectively. Six (6) concrete mix designs experimental specimens were cast and evaluated. These comprised a control mix (100% OPC and natural sand) and five modified mixes with 10%, 15%, 20%, and 25% laterite substitution for sand, each combined with 10% metakaolin replacement of cement. Concrete testing was undertaken at 7, 28, and 56 days, followed by statistical analysis of performance. The study revealed the 15% Laterite-Metakaolin composite (SLMK) replacement level as the optimum formulation for paver blocks, demonstrating the best balance of mechanical performance and consistency. The Control Mix achieved the highest overall strengths of 35.41 N/mm2 in compressive strength and 2.53 N/mm2 in split tensile strength at 56 days. Among the modified mixes, the 15% SLMK mix consistently had the highest strengths, with a 56-day compressive strength of 17.73 N/mm2 and a split tensile strength of 1.77 N/mm2. The study also revealed that strength development declined at lower replacement levels. Statistical analysis revealed that the 15% SLMK mix had the highest mean strength among modified mixes with the lowest Coefficient of Variation, indicating superior reliability and consistency. These findings demonstrate the potential of using 15% SLMK to produce structurally acceptable paver blocks while meeting sustainability goals.