Use of Taguchi method to evaluate the unconfined compressive strength of quicklime stabilized silty clayey subgrade

Abstract

For practical deployment of lime-stabilized subgrade in the engineering field, laboratory and field-based pavement design studies highlight the significance of simpler preparation and maintenance techniques. In this article, sets of samples were prepared using Taguchi L9 orthogonal array to quantify and assess the dry density, lime, and water content's effect on the unconfined compressive strength (UCS). Scanning electron microscope analysis and X-ray diffraction test were further conducted on prepared samples. The average UCS was estimated by multivariate regression analysis using the stepwise approach. Test results suggested that the lime content significantly influenced the average UCS, followed by the water content and dry density. In addition, whether the dry density is positively or negatively related to the average UCS depends on the level of the water content and lime content. A statistical regression model considering the interaction terms is proposed to predict the average UCS during the design of pavement foundations and evaluate the UCS. The stabilized soils’ variations in lime content, water content, and dry density nearly showed similar x-ray diffraction peaks. However, a marked change in the microstructure of the tested samples confirmed the results of the UCS test. The proper understanding and characterization of the effect of dry density, lime, and water content on soil strength and stiffness are vital for an enhanced design of pavement foundations. The dry density, lime, and water content should be carefully controlled during construction to realize design objectives.