USE OF LATERITE AS PARTIAL SAND REPLACEMENT IN SANDCRETE BLOCKS: STRENGTH AND PERMEABILITY STUDY

This study examined the effect of replacing part of sand with laterite in sandcrete block production and how the permeability of fine aggregates influences block strength. First, the fine aggregates (river sand and two laterite samples) were tested to determine their physicochemical properties (moisture content, specific gravity and permeability). The sandcrete blocks were then produced using a 1:6 mix ratio with laterite replacement levels of 0%, 25%, 50% and 75%, and cured for 7, 14 and 28 days. Density and compressive strength were determined, and correlation analysis was performed between aggregate permeability and 28-day block strength. The results showed that the laterites had higher moisture content and lower permeability than the river sand. The control sample (100% sand) had the highest strength, whereas the 25% laterite mixes achieved compressive strength values above the minimum requirement for non-load-bearing sandcrete blocks. The 50% and 75% mixtures did not meet the standard. Block density and compressive strength reduced as laterite content increased. A strong positive correlation was observed between the permeability and 28-day strength of the block samples, and aggregates with higher permeability produced stronger blocks. The optimal replacement level is 25% laterite. Higher laterite contents weaken the block structure and are unsuitable for major construction.