The Effect of Additives in Hot Asphalt Mixtures

Abstract

The increase in road traffic during the last two decades in combination with an insufficient degree of maintenance due to shortage in funds have caused an accelerated and continuous deterioration of the road network in Iraq. To alleviate this process, several types of measures may be effective, e.g., securing funds for maintenance, improved roadway design, use of better quality of materials and the use of more effective construction methods. In this research, waste plastic bags as one sort of polymers and polypropylene fiber are used to investigate the potential prospects to enhance asphalt mixture properties. The objectives also include determining which one of the two additives is better than the other to be used and its proportion. The two additives were introduced to the mixture in state of small pieces (2-4 mm). Marshall mix design was used, first to determine the optimum bitumen binder content and then further to test the modified mixture properties. In total, (51) samples were prepared (15 samples were used to determine the optimum binder content and the remaining samples were used to investigate the effect of modifying the asphalt mixtures). The optimum asphalt content was (5 %). Six proportions of each additive type and stated by weight of the optimum binder content were selected to be tested (2, 4, 6, 8, 10, and 12%). The tests include the determination of bulk density, stability and flow.