The Impact of Cement and Rice Husk Ash on the Unconfined Compressive Strength of Expansive Clay Soil

The soil in Kedungdandang Hamlet, Muncar, has previously been identified as expansive clay that is highly sensitive to changes in moisture content and exhibits significant shrink–swell behavior, which leads to a reduction in bearing capacity and structural damage such as cracking in floors and walls, therefore, soil improvement through stabilization is required. This study aims to determine the effect of adding cement and rice husk ash (RHA) on the mechanical properties of expansive clay soil by using 3% cement and 6%, 8%, and 10% rice husk ash based on the weight of the soil. The results of the unconfined compressive strength (UCT) test indicate that the natural soil has a qu value of 28.62 kN/m², which increases to 55.08 kN/m² with the addition of 3% cement and 6% RHA, to 62.66 kN/m² with 3% cement and 8% RHA, and reaches the highest value of 86.98 kN/m² for the mixture containing 3% cement and 10% RHA. This increase in qu value indicates that the stabilization process improves the mechanical properties of the soil through a pozzolanic reaction, resulting in a more stable soil structure and a higher bearing capacity.