Optimization of the Compressive Strength Properties of Laterite Saw- Dust Ash Sandcrete Bricks for Road Paving Applications

Abstract: The production of Ordinary Portland Cement (OPC) is a significant source of global CO2 emissions, driving the need for sustainable alternatives in construction materials. This study investigates the optimization of sandcrete bricks incorporating laterite soil and sawdust ash (SDA) as partial replacements for cement and fine aggregate, specifically for road paving applications. A comprehensive experimental program was executed using a Scheffé's mixture design with five components water, cement, SDA, fine aggregate, and laterite generating 35 distinct mixtures. The compressive strength of these mixtures was determined at 28 days, and the data were utilized to develop a highly accurate third-degree polynomial regression model (R² = 0.9954). The results demonstrate that optimal mixtures with moderate SDA (5-10%) and laterite (5-15%) content can achieve compressive strengths exceeding 51 MPa, comparable to conventional sandcrete. However, higher replacement levels induced a strength reduction of up to 28%, attributed to cement dilution and the deleterious effects of elevated alkali content in SDA. Computational optimization identified seven optimal mix proportions with predicted compressive strengths ranging from 32 MPa to 37 MPa, suitable for structural paving elements like kerbs and interlocking blocks. This research conclusively establishes that laterite and SDA are viable supplementary cementitious materials, but their successful application hinges on precise proportioning to leverage their pozzolanic benefits while mitigating their adverse effects, thereby offering a pathway for more eco-friendly construction in the roadway sector. Keywords: Sustainable Construction; Sawdust Ash; Laterite; Scheffé's Optimization; Sandcrete Bricks; Compressive Strength; Road Paving.