Scheffe’s Optimization of the Compressive and Flexural Strengths of a Self-Compacting Laterite Concrete

Abstract

This research investigates the use of laterite as a partial replacement for fine aggregate in self-compacting concrete (SCC) with the aim of enhancing sustainability, reducing material cost, and promoting the utilization of locally available materials. A total of 56 concrete mix proportions were developed using Scheffé’s simplex lattice design method N(6,3) to systematically assess the effects of varying laterite contents on compressive strength, flexural strength, and workability. Hydroplast 260GR, a high-range water-reducing admixture, was incorporated at dosages of up to 2.0% by weight of cement to achieve adequate flowability while minimizing water demand. The compressive strength of the SCC mixes ranged from 12.90 MPa to 22.70 MPa, while flexural strength values varied between 2.42 MPa and 3.22 MPa. Results revealed a general reduction in strength with increasing laterite content, particularly at higher replacement levels. However, several optimized mixes satisfied the minimum strength requirements for structural concrete. Slump flow values ranged between 550 mm and 590 mm, meeting EFNARC specifications for SCC. Regression models developed for compressive and flexural strengths demonstrated strong predictive capability, with coefficients of determination (R²) exceeding 97%. Analysis of variance (ANOVA) confirmed the statistical significance of the models. Optimization results indicated that an SCC mix containing approximately 4.95% laterite by volume of fine aggregate achieved a compressive strength of 21.67 MPa and a flexural strength of 3.13 MPa, with a corresponding 3.5% reduction in production cost. The findings confirm that laterite can be effectively utilized in SCC for sustainable construction applications.