Evaluating the Unconfined Compressive Strength Retention of Corn Starch Stabilized Lateritic Soils

Abstract

This study evaluates the effectiveness of corn starch as a sustainable stabilizer for lateritic soils, focusing on unconfined compressive strength (UCS) retention under wet–dry cycles. A (3,2) Scheffé simplex lattice design was employed to vary lateritic soil, corn starch, and water-to-solids (w/s) ratio across 12 mixes (6 trial, 6 control). Samples were cured for 28 days, then subjected to 12 wet–dry cycles to assess UCS retention. UCS retention ranged from 69.68% to 90.12% for trial mixes and 69.68% to 91.24% for control mixes, indicating strong durability. The best-performing mixes exceeded 90%, confirming corn starch’s potential for long-term stabilization. The Scheffé regression model developed had an R² of 0.998 and an F-value of 1.056 (< F-critical of 5.05), confirming predictive reliability and statistical adequacy. Model coefficients showed corn starch had the greatest influence (β₂ = 87.50), followed by lateritic soil (β₁ = 83.33) and water-to-solids ratio (β₃ = 69.68). Positive interactions between lateritic soil and corn starch (18.82) and between lateritic soil and water-to-solids ratio (43.98) improved retention, while a slight negative effect between corn starch and water-to-solids ratio (−0.72) indicated that excess water could reduce binding. Overall, corn starch significantly improves UCS retention, offering a durable, eco-friendly solution for lateritic soil stabilization.