Surface modified ground rubber tire by grafting acrylic acid for paving applications

Surface modification of ground rubber tire (GRT) was performed by bulk polymerization of acrylic acid (AA) without using any initiator. Two different sizes of GRT were used for this project: 40 mesh (often used in Asphalt Industry), and 300 mesh which is used in other industries. The concentration of the monomer (acrylic acid), reaction temperature and the reaction time (1 and 3 h) are important factors on the grafting degree – especially because our goal was not to use any initiator during the reaction (there are well known procedures for grafting of polymers by using different type of initiators). Our effort was towards simplifying the grafting process and to make it much faster and less expensive (more acceptable by the industry). The microstructural and morphological changes of the GRT particles were characterized by Attenuated Total Reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), viscosity test of the modified asphalt binder [PG 64-22 asphalt binder with virgin GRT particles (40 and 300 mesh), and PG 64-asphalt binder with AA treated GRT particles of the same size]. Dynamic shear rheometer (DSR) test of the modified asphalt binder was also performed. Thermal gravimetric analysis (TGA) was investigated on untreated and AA treated 300 mesh GRT particles. Results showed that with the addition of surface modified GRT particles increased the viscosity and failure temperature values of asphalt binder regardless of binder source and grade.