In this study, the influence of two chemical additives, (i.e., poly(vinyl alcohol), PVA and 1,2,3,4 Butane Tetra Carboxylic Acid, BTCA on the engineering properties of an expansive clay soil is investigated. The effect of polymers on the unconfined compression strength of soil samples prepared at maximum dry unit weight (i.e., 16.2 kN/m³ and 17% water content) and a lower dry unit weight (i.e. 10.8 kN/m³ and 48% water content) was evaluated. PVA and BTCA added at dosages of 0.1% to 1.5% and 0.1% to 0.5% respectively to both compacted soil samples and cured for 1 and 14 days. The results of unconfined compression tests on clay soil samples stabilized with different PVA and BTCA contents cured for 1 and 14 days indicated that such hydrophilic polymers improve the compression strength of both dense and soft clay soils significantly and their strength even increases with curing time. However, the efficiency of the additives is highly dependent on the unit weight of the soil. Furthermore, the durability of stabilized samples was also examined using soaking tests and results revealed that these polymers improve the durability of clay soils once they are soaked under water.