Not all rigid pavement built on the good subgrade. Expansive soils are one of the types of problematic soil. Expansive soils are a type of soil that has swelling and shrinkage potential caused by soil’s water content, decrease in soil bearing capacity, and swelling pressure. Slab reinforcement with a single pile is one to improve the pavement by spreading the load to the subgrade. The aim of this study is to analyse slab and slab with single pile deformation behaviour due to loading and subgrade swelling and analyze modulus of subgrade reaction. On the road pavement system, soil bearing capacity definite as modulus of subgrade reaction. Slab reinforcement with a pile will change the behaviour of slab with a single pile on loading and subgrade swelling and analyse the modulus of the subgrade reaction value. This research is a laboratory modeling that focused to determine the value of modulus of subgrade reaction (kv) with a slab using 10 cm and 20 cm length cylindrical pile with a diameter of 4 cm. This study has identified and analysis results vertical displacement for specimen one in the amount of 1,135×10-4 m on fine conditions with the value of kv 4,405×104 kN/m3, specimen two in the amount of 5,700×10-4 m on fine conditions with the value of kv 3,860×104 kN/m3, and specimen three in the amount of 5,100×10-4 m on fine conditions with the value of kv 3,529E+04 kN/m3 show that single pile reinforcement can reduce slab vertical displacement. In summary, these results show that the swelling decrease in the amount of 11,88 cm on soil and 12,11 cm on slab compared to a slab without single pile reinforcement. The piles were able to reduce vertical displacement in the amount of 40,48% on fine conditions and 53,15% on bad conditions.