This study investigates the optimization of Ordinary Portland Cement (OPC)–Rice Husk Ash (RHA) stabilized lateritic soil for the production of sustainable structural earth blocks. The research was designed to evaluate the pozzolanic activity of RHA, examine the consolidation and compressive strength characteristics of the stabilized soil blends, identify optimal mix ratios, and provide recommendations for practical applications in sustainable construction. Laboratory experiments, supported by statistical and computational modelling using the NonLinearModelFit function in the Wolfram Language, were conducted on thirty-five (35) mixture formulations based on Scheffé’s optimization algorithm. Chemical analysis revealed that RHA contained 70.48% SiO₂, confirming its status as a highly reactive pozzolan suitable for cementitious applications. The inclusion of RHA and OPC significantly improved the consolidation properties of the lateritic soil, as reflected by reduced coefficients of compressibility and enhanced stiffness. The compressive strength tests indicated that moderate RHA replacement (approximately 15%) combined with 30% OPC yielded optimal performance, achieving strengths in the range of 3.7–4.6 MPa suitable for structural block applications. The derived nonlinear mixture models achieved high predictive accuracy (R² = 97.8–99.4%), validating their reliability for mix proportion optimization. The study concludes that the synergistic use of OPC and RHA effectively enhances the engineering properties of lateritic soil while promoting sustainable, low-carbon construction. Consequently, the optimized cement–RHA–laterite blend is recommended as an eco-efficient material for the production of durable and affordable structural earth blocks in tropical environments.

This study successfully optimized the strength and durability properties of Abuja laterite stabilized with Ordinary Portland Cement and Rice Husk Ash for structural earth block production. Mineralogical analysis confirmed the high pozzolanic potential of RHA due to its silica content. The natural laterite exhibited low plasticity and favorable characteristics for stabilization. The incorporation of OPC and RHA significantly improved consolidation behaviour by reducing compressibility and enhancing stiffness. Compressive strength results demonstrated that moderate RHA replacement combined with adequate OPC content produced stabilized blocks with strengths suitable for structural applications. Computational optimization using Scheffé’s fourth-degree polynomial model yielded highly reliable predictive equations, with R² values exceeding 97%. Overall, the study confirms that properly proportioned OPC–RHA blends can enhance both mechanical performance and sustainability of lateritic earth blocks.

Akinmusuru, J. O. (2011). Stabilization of lateritic soils with cement and agricultural wastes. Construction and Building Materials, 25(2), 521–525. Alhassan, A. A. (2008). Potentials of rice husk ash for soil stabilization. Assumption University Journal of Technology, 12(4), 266–273. Das, B. M., & Sobhan, K. (2014). Principles of geotechnical engineering (8th ed.). Cengage Learning. Mehta, P. K., & Monteiro, P. J. M. (2014). Concrete: Microstructure, properties, and materials (4th ed.). McGraw-Hill. Montgomery, D. C. (2013). Design and analysis of experiments (8th ed.). John Wiley & Sons. Myers, R. H., Montgomery, D. C., & Anderson-Cook, C. M. (2009). Response surface methodology: Process and product optimization using designed experiments (3rd ed.). John Wiley & Sons. Osinubi, K. J. (1998). Influence of compactive efforts on cement-treated lateritic soils. Journal of Materials in Civil Engineering, 10(2), 65–72. Osinubi, K. J., & Eberemu, A. O. (2010). Stabilization of lateritic soil with rice husk ash. Journal of Materials in Civil Engineering, 22(5), 452–460. Scheffé, H. (1958). Experiments with mixtures. Journal of the Royal Statistical Society: Series B (Methodological), 20(2), 344–360. Scheffé, H. (1963). The simplex-centroid design for experiments with mixtures. Journal of the Royal Statistical Society: Series B (Methodological), 25(2), 235–263. Terzaghi, K. (1943). Theoretical soil mechanics. John Wiley & Sons.

© 2025 International Journal of Engineering and Techniques (IJET).

Digital Object Identifier (DOI)

IJET assigns a unique DOI to every accepted article via Zenodo for persistent linking and citation. Your article’s DOI: https://doi.org/{{doi}}

Open DOI About Zenodo DOI

Close