Effect of Sawdust Ash on the Compressive Strength and Sorptivity of Laterised Concrete

This paper investigated the effect of sawdust ash (SDA) on the compressive strength and sorptivity of laterised concrete. Compressive strength up to 28 days and sorptivity at 28, 90 and 180 days were obtained at the laterite contents of 20 and 40% as partial replacement for sand and SDA contents of 10, 20, 30 and 40% as partial replacement for Portland cement (PC). Fifteen concrete mixes were investigated at the water/cement ratios of 0.30, 0.50 and 0.70 and assessed at equal 28-day strengths of 20-40 N/mm2. At equal water/cement ratios, while compressive strength reduced by 0.76-0.79% for a percentage replacement of sand with laterite and by 1.26-1.63% for a percentage replacement of PC with SDA, sorptivity increased by 0.82-0.90% for a percentage replacement of sand with laterite and by 0.52-1.16% for a percentage replacement of PC with SDA. However, at equal strengths, laterised and SDA-laterised concretes, at up to 40% laterite and SDA contents, have higher resistance to sorption than the conventional PC concrete. Keywords: absorption, compressive strength, laterised concrete, permeation resistance, sawdust ash