Scheffe’s approach for single additive optimization in selected soils amelioration studies for cleaner environment and sustainable subgrade materials

Abstract

Soil materials with poor engineering performance such as those rich in clay are prevalent across the globe. The clayey nature of these soils is of one the factors responsible for the low and excess volumetric changes in the soil which constitutes the foundation failures of most civil engineering infrastructures. For that reason, this present-day study demonstrates practically on optimizing additive for the purpose of ameliorating black expansive clay soil (ECS) and lateritic soil (LS) materials, respectively. Thus, a total of twelve (12) different mix combinations of water, soil and cement kiln dust (CKD) for both (ECS and LS) based on Scheffe’s strategy were taken into consideration for the experimental protocols. Interestingly, the experimental response included California bearing ratio and unconfined compressive strength. Based on the Scheffe design of experiment, the most favourable outcome was recorded at 1.0:0.9:0.3 for soil, CKD and water, respectively. Based on the upshots, statistical indicators such as t-test and ANOVA were deployed in testing the formulated models' adequacy. In addition, qualitative test such as scanning electron micrographs and fibermetric analysis of the virgin soil materials were at variance with soil materials altered with additive. Furthermore, these variations are indicator towards the build-ups of cementitious compounds and this confirms clearly the feasibility of reusing CKD combined with Scheffe optimisation approach in soil re-engineering studies.