The final disposal of scrap tires is an extremely serious environmental problem nowadays. Generally, every tire ever manufactured is discarded, posing a potential threat to public health and the environment. The reuse of scrap tires has become a challenge all over the world, since this material takes nearly 600 years to decompose completely. On the other hand, the construction and maintenance of road pavements should be long lasting due to their major impact on the economy of a nation. The main reasons for the weak performance of roads include the increase in the overall traffic, poor material quality and/or climatic effects. Therefore, the need for better performance of pavements has constrained pavement engineers to develop the modified asphalts. The modified asphalt mainly improves permanent deformation (rutting), fatigue, low-temperature cracking, friction resistance, and adherence of pavements. Researchers have shown that ground tire rubber can be added to asphalt compositions. Mainly, the use of this material partially reduces the need for new raw materials while improves the performance and life cycle of asphalt pavements. Rubber modified asphalt-concrete is an environmentally correct solution. The obvious benefit of adding rubber to bitumen is that the rubber imparts elasticity to the binder, which helps increscent in fatigue life of flexible pavements, as well as reduces reflective cracking. This elasticity can also improve pavement flexibility and resistance to low-temperature cracking. It has been reported that rubber also improves the aging resistance, the tensile strength, ductility, toughness, resiliency, tenacity, and thus, the durability of rubber-modified asphalt mixtures. This dissertation investigates the effects of structural and blending conditions of rubber particles on bitumen behavior by using four types of tests i.e. Pull-out, FTIR, DSR and PG. The pull-out test was designed to investigate the interfacial shear stress between asphalt (neat and/or modified) and aggregate. According to the experimental design, the effects of rubber particle content, blending temperature, mixing time and types of aggregate (limestone and/or steel slag) were investigated on the pull-out force. The optimized conditions of preparation of rubber-modified asphalt-concrete were obtained. Therefore, with the optimum condition of preparation, further tests were being conducted. The FTIR test was designed to investigate the interaction between binder and rubber. After that to investigate the performance of asphalt rubber concrete, the dynamic shear rheometer (DSR) test was conducted. Consequently, performance grade (PG) of asphalt rubber was carried out to evaluate the high temperature performance of asphalt. Studies and experiments indicate that use of ground rubber to modify binder is desirable from stand point of technical In addition, it is desirable from an environmental point of view and economic standpoint. Key Words rubber asphalt, crumb rubber, reclaimed rubber, Pull-out test, FTIR, Dynamic shear rheometer test, Performance grade.
