| The moisture damage is one of the main failure modes affecting on the flexible pavement performance. The stripping action of water helping to reduce the bonding strength between the asphalt binder and the aggregate particles. The moisture damage resistance depends on many factors: asphalt binder, aggregate type, and mineral filler. This study has been made to evaluate the effect of SBS on the moisture sensitivity. The asphalt mixtures are divided into two types: the unmodified, and the modified. The SBS content was (0.5, 1.0, 1.5, 2.0, 2.5, 3.0.3.5, 4.0) % by the weight of asphalt. The performance tests include: Marshall Test, Indirect Tensile Strength Ratio test, and the Index of Retained Strength test. The tests results show that the asphalt mixtures modified by SBS have shown a developed in the Marshall properties, and increasing the moisture damage resistance. However, the using of (3% SBS) by the weight of asphalt has the best effect on the Marshall properties, and on the moisture damage resistance, which increase the pavement performance against the environmental effects |