Strength characteristics of kaolin clay mixed with RHA, sand and lime

Abstract

Kaolin clays are inadequate for supporting overlying pavement and foundation structures due to their low bearing capacity and volumetric variations. Soil stabilization is the possible solution for resolving these issues and increasing the soil's bearing capacity. The viability of using an agricultural waste product like rice husk ash along with sand and lime as effective medium expansive kaolin clay stabilizers was investigated through experimental assessment. The unconfined compressive strength and split tensile strength of samples at optimum moisture content were evaluated using 28 different combinations of RHA (10%, 20%, and 30% of the weight of untreated clay), lime (6%, 9%, and 12% of the weight of untreated clay), and sand (10%, 15%, 20%, and 25% of the weight of untreated clay) over three distinct phases of curing (0, 7, and 28 days). The MDD increases with the addition of sand, while the OMC decreases. With increasing curing periods, UCS values increased. The samples for the UCS test and the STS test were prepared and cured in a humidity chamber at three different lime contents (6%, 9%, and 12% by weight). The initial UCS of pure kaolin clay was 155.68 kPa, which improved to 1311.23 kPa after 9% lime treatment with 28 days of curing. The STS of untreated clay was 14.2 kPa, which improved to 36.94 kPa after 9% lime treatment with 28 days of curing. According to the findings, a mixture of clay, RHA, lime, and sand can be employed as lightweight fill material in embankments and retaining walls. It also provides a safe option for managing rice husk ash as an excellent subgrade element for pavement construction.