Evaluation of modified asphalt mixtures with APP and IPP polymers by fatigue distress criteria

Abstract

In the present, a lot of distress is shown on the highway; this has been happened due to the increase in the numbers and loads of vehicles, and poor strength of asphalt pavement. The main objective of this research is to study the effect of adding atactic polypropylene (APP) and isotactic polypropylene (IPP) polymers as an additive to the asphalt mixture on the life of the highway. The polymers had been added to the asphalt mixture at (2%, 4%, and 6% by the weight of asphalt content with performance grade PG 64-16 at (5.2 ± 0.5%) by weight of asphalt mixture. The SUPPERPAVE design had been used to prepare 100 cylinder and 288 beam samples to test indirect tensile strength, punching shear strength, and four-point bending beams with temperatures (10, 25, and 40 °C) and two micro-strains (400, and 750 μs). The study observed that 2% of APP and IPP of the modified mixture gave the best result for all tests and also found that the fatigue life has a positive relationship with the increase in asphalt content and temperature, while it has a negative relationship with the increase in micro-strain. The study achieved that the use of APP polymer has the best effect on the asphalt mixture. Finally, it has concluded that all modified asphalt tests have got better results than the reference mixture. Consequently, the improved asphalt with both polymers gave an increase in the service life of the highway by increasing the resistance of the asphalt mixture to stresses.