The researchers aimed to strengthen soft clay soil by using sand columns, comparing those with and without expansion. Sand columns can boost soil support and are cost-effective by using local sand. Tests showed expanded sand columns didn't expand as expected, but they got denser by 85.498% and 82.05% compared to normal sand columns at 73.863%. The expanded sand columns could hold 12% to 14% more weight. The cost for normal sand columns was Rp 2,381,480.98 while expanded ones were Rp 2,404,016.15. Expansion increased soft clay soil strength despite the added cost.