Today, high-performance requirements for asphalt pavements demand enhanced properties for bitumen to withstand the environmental condition and traffic demand.On the other hand, the rapid growth in population and economy results in a continuously increased material consumption, and subsequently waste generation. Among various waste materials, rubber and plastic, including high-density polyethylene (HDPE), constitute some part of the non-biodegradable solid wastes worldwide. Because of the great difficulties in managing the non-biodegradable wastes and the required volume of bitumen, the idea of using plastic and rubber as bitumen modifier in new asphalt mixtures appears to be an effective and meaningful utilization of these materials. As binder plays an important role in the final performance of the asphalt mixture, an understanding of modified binder properties is essential in designing an asphalt mixture. To this point, since compatibility of asphalt mixture with polymer is the most important factor in the blend of polymers and asphalt, the properties of the waste polymers were evaluated in this ongoing research by means of advanced thermal analysis and scanning electron microscope (SEM). This chapter presents the results of this experimental study to evaluate the properties of polymers as potential modifier for virgin bitumen in asphalt mixture.A large number of procedures have described different fractions in bitumen. Based on the most common procedure, bitumen is divided into four generic groups of saturates, aromatics, resins, and asphaltenes, namely SARAs. The molecular weight of these fractions increases in the order S < A < R < A [1].The structure of bitumen is mostly regarded as a colloidal system. In this system, the asphaltene particles are dispersed into the oily dispersion medium called the maltenes, which is composed of saturates, aromatics, and resins. As illustrated in Figure 1, a shell of resins has covered the asphaltene particles. The temperature and equilibrium between the covering part and dissolved part of resins affect the shell thickness [2][3][4].
Modified Asphalt 110Evaluation of Structural and Thermal Properties of Rubber and HDPE for Utilization as Binder Modifier http://dx.doi.org/10.5772/intechopen.75535 113