Modification of Asphalt using Castor Oil Based Polyurethane

Asphalt is the most used binder for road paving due to its adhesive and water proofing properties. Since bitumen (asphalt) has low softening point and thermal stability, making it prove to permanent deformation and fatigue. In order to maximize it resistance to permanent deformation and to reduce the fatigue, bitumen used to be modified with various additive. Normally additive used for the modification are styrene butadiene styrene (SBS) co-polymer, reactive ethylene terpolymer, ethylene vinyl acetate rubber etc. by using polyurethane (PU), can have added advantage of easy handling and more durability etc. Pre-added polyol to bitumen make it more flowable and liquid to make it ease of handling. In the present work, different reaction parameters such as the effect of reaction time, effect of catalyst and effect of OH to NCO ration was optimized. PU modified asphalt shows hardness value i. e.21-32mm and softening point i. e.53oC-63oC. Unmodified asphalt have the 89mm hardness value and 43oC softening temperature.