Sugarcane press mud modification of expansive soil stabilized at optimum lime content: Strength, mineralogy and microstructural investigation

This study attempted to investigate the potential of sugarcane press mud (PM) as a secondary additive in conjunction with lime for the stabilization of an expansive soil. The physico-mechanical properties of an expansive soil, such as plasticity, shrink-swell behavior, unconfined compressive strength (UCS), mineralogical and microstructural characteristics were investigated. The expansive soil was stabilized at its optimum lime content (7%) for producing maximum strength, and was modified with four different quantities of PM in small dosages (0.25%–2%). Cylindrical soil samples, 38 mm in diameter and 76 mm in height, were cast and cured for varying periods to evaluate the strength of the amended soil. The spent samples after strength tests were further used for determination of other properties. The test results revealed that PM modification led to a substantial improvement in 7-d strength and noticeable increase in 28-d strength of the lime-stabilized soil (LSS). The addition of PM does not cause any detrimental changes to the shrink–swell properties as well as plasticity nature of the stabilized soil, despite being a material of organic origin. Mineralogical investigation revealed that the formation of calcium silicate hydrate (CSH) minerals, similar to that of pure lime stabilization with only the type of mineral varying due to the modification of PM addition, does not significantly alter the microstructure of the LSS except for superficial changes being noticed.