Assessment of Eco-Friendly Lightweight Interlocking Concrete Paving Units Incorporating Sawdust Waste and Laterite

Abstract This study assessed the performance of eco-friendly lightweight interlocking concrete paving units incorporating sawdust waste as a partial fine aggregate replacement and lateritic soil as a partial cement replacement. Four mixes were prepared at combined replacement levels of 0, 5, 10 and 15 percent and cured for 7, 14 and 28 days. Compressive strength, flexural strength, bulk density and water absorption were tested against EN 1338:2003 and EN 206 limits. Two-way ANOVA, Tukey's HSD, regression, response surface methodology and a desirability function were applied. Twenty-eight-day compressive strength ranged from 24.8 MPa (control) to 16.4 MPa (15 percent), all meeting the 15.0 MPa minimum. Strength and density decreased with replacement while water absorption increased; the 15 percent mix exceeded the absorption limit. Optimisation identified 7.8–8.2 percent as the best compromise level. Moderate sawdust-laterite replacement produces structurally adequate, lighter paving units suited to sustainable pavement production in Nigeria.