Chemical, morphological, and rheological properties of biopolymer-modified asphalt containing waste polystyrene and pine resin

In recent years, much attention has been paid to improving the performance of asphalt binders, such as the use of polymers. Numerous investigations have shown that polymer modified asphalt exhibits a good resistance to rutting and reduced thermal cracking. However, incompatibility between asphalt and polymer occurs when a polymer is applied in high proportion. Using pine resin obtained from pine trees is expected as one approach to overcome this incompatibility. This study investigates the properties of biopolymer-modified asphalt consisting of conventional asphalt (60/70 penetration grade asphalt), waste polystyrene, and pine resin. Waste polystyrene at percentages of 4%, 6%, and 8% was blended with conventional asphalt, whereas 3% pine resin was applied to all mixtures. A series of tests was conducted, including penetration, softening point, flash point, ductility, specific gravity, mass loss, FTIR, SEM, EDX, and DSR. The results of the tests indicated that the pine resin predominantly contained aromatic oil, which is a good solvent to disperse waste polystyrene uniformly, thus increasing the compatibility of the mixture. The utilization of 6% and 8% waste polystyrene and pine resin improves the performance grade of the conventional asphalt binder, which is equal to PG 64 to PG 70.