Soft clay is often a problem in the implementation of highway construction because clay has great development potential and low carrying capacity. This research was conducted by stabilizing soft clay soil with a mixture of well graded soil. Soft clay samples were taken from Punggur and well graded soils were taken from Kampung Tua Belian. The study used a mixture of 20%, 30%, 40%, and 50% well graded soil stabilization materials and an immersion period of 4 days. This research covers the

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... l and mechanical properties of clay in terms of optimum moisture content, laboratory CBR, and free compression test (UCT). The data obtained from research activities were analyzed descriptively in the form of tables and graphs of relationships. The results showed that the soft clay from Punggur had a specific gravity of 2,497 with the addition of well graded soil composition up to 50%, the liquid limit decreased to 67.75%, the plastic limit decreased to 37.69%, and the plasticity index decreased to 30.07%. . The addition of well graded soil composition up to 50% changed the Unified system, the soil type changed from the OH group to SC-SM, while according to the AASHTO system, the soil type did not change. The value of laboratory CBR and free compression test (UCT) increased along with the increase in the composition of the well graded soil.