Effect of Polystyrene Polymer Modifier and Glass Powder Filler on the Mechanical Characteristics of Hot Mix Asphalt

The main objective, of this research, was studied the mechanical performance of hot mix asphalt that used powder of glass as mineral filler and improved with polystyrene polymer as a modifier and found the best percentages of combine polystyrene and glass powder that give optimal mechanical properties of asphalt mixture. This purpose was achieved by testing asphalt mixture samples with Marshall tests system and found the Marshall stability, bulk specific gravity and air voids. The work plan of this study, included prepare a specimens of hot mix asphalt according to Marshall procedure of asphalt mix design and ASTM standard method (D 1559). The specimens prepared by one gradation of aggregate (with maximum size 12.5 mm according to SCRB specification) mixed with one type of asphalt ( 40 - 50 penetration grade), five different percentages of asphalt cement content (4.5, 4.75, 5.0, 5.25, 5.5) % (by total weight of mix), three different percentages of waste glass powder (5, 7, 9) % (by total weight of aggregate) and five different percentages of polystyrene polymer (0, 1, 2, 3, 4, 5) % (by total weight of asphalt cement) each specimen was compacted by Marshall compactor to 75 blow in each face. The laboratory tests that performed, in this study, on the prepared were 1. Marshal Method, 2. Standard test of Bulk specific gravity.3. Standard Test Method for calculating the Percent of Air Voids. From the results of testing samples in laboratory the following conclusions could be made The using of polystyrene as a modifier lead to increasing the stability and bulk specific gravity of asphalt mixture and lead to decrease the air voids within the mixture. Increasing of glass powder filler from 5 % to 7 % lead to increase the stability and specific gravity slightly, while the increasing of glass powder filler from 7 % to 9 % lead to decrease the stability and specific gravity. Increasing of glass powder leads to decreasing the air voids within the asphalt mixture. Preferable percentage of asphalt content, polystyrene content and glass powder filler, that gave best performance of asphalt mixture, were (5 %, 4 %, 7 %) respectively.