Mechanical Properties Optimization of Soil—Cement Kiln Dust Mixture Using Extreme Vertex Design

As a result of environmental issues, the use waste residue has gained much attention in the field of soil re-engineering, this is because of the feasibility of using waste derivatives in soil amelioration protocols. This necessitated the current study to deal with the utilization of an industrial residue termed as cement kiln dust (CKD) in enhancing the mechanical performance of black expansive clayey material. The amelioration protocols were as a result of the poor engineering performance of black cotton soil thereby becoming a road cancer material. The extreme vertex design (EVD) is a flexible approach and was adopted for the mixture experimental design and modelling of the mechanical properties of problematic black cotton soil—cement kiln dust blend. The statistical analyses and or approaches engaged in course of this study were carried out using Minitab 18 and Design Expert statistical software. In the current study, the responses considered include California bearing ratio (soaked and unsoaked) and unconfined compressive strength test. The corresponding experimental responses were then achieved in the laboratory and used for analysis and model development. Statistical diagnostics and influence tests carried out on the developed model showed a good correlation with the actual results. However, using the EVD design of experiment approach, the peak performance of soil-CKD was achieved at the mixture combination of 0.45, 0.443 and 0.107% for soil, CKD and water, respectively. The strength outcomes indicate that cement kiln dust could be useful in ameliorating expansive soil for sub-base material of low trafficked roads and as well reduce cost of cement kiln dust residue disposal.