Effect of Water–Cement Ratio and Laterite Particle Size on the Strength, Workability of Laterite–Cement Blocks

This study investigates the influence of the nominal water–cement (W/C) ratio and laterite particle-size characteristics on the workability, compaction behaviour, and compressive strength of laterite–cement mixtures produced from soils obtained from Agu Awka and Umueri in Anambra State, Nigeria. The experimental programme employed a 1:6 cement-to-laterite proportion and W/C ratios of 0.30, 0.40, 0.50, and 0.55. Laboratory investigations included particle-size distribution, compaction characteristics, Atterberg limits, slump, compressive strength at 7, 14, 21, and 28 days, and water absorption. The results showed that the Agu Awka soil attained a substantially higher maximum dry unit weight of 18.63 kN/m³ compared with 13.42 kN/m³ for the Umueri soil, while the corresponding optimum moisture contents were approximately 12.8% and 13.8%, respectively. The Agu Awka soil also exhibited lower plasticity, with a liquid limit (LL) of 25.0% and plasticity index (PI) of 7.73%, compared with an LL of 42.0% and PI of 16.3% for the Umueri soil. Slump increased consistently with increasing W/C ratio, rising from approximately 2.4–2.5 mm at W/C = 0.30 to about 20.1–20.3 mm at W/C = 0.55. In contrast, the mean 28-day compressive strength decreased from 3.43 MPa at W/C = 0.30 to 1.37 MPa at W/C = 0.55. Water absorption also decreased as the W/C ratio increased.The findings demonstrate that the source and particle-size characteristics of laterite can significantly influence the compaction behaviour and moisture requirements of laterite–cement mixtures. The study further concludes that, where adequate compaction is achieved, lower W/C ratios can contribute to higher compressive strength in laterite–cement blocks.