Performance Evaluation of Asphalt Mixtures Modified with Rubber Powder and a Crosslinking Agent at Medium and Low Temperatures

چکیده مقاله

In recent years, the use of rubber powder in modifying bitumen and asphalt mixtures has yielded economic benefits, reduced environmental pollution, and enhanced the performance of flexible pavements. At the same time, the most significant disadvantage of modifying bitumen with rubber powder is the low storage stability of rubber powder-modified bitumen. This study investigates the laboratory results of modifying bitumen and asphalt mixtures with rubber powder at different percentages and in the presence of a crosslinking agent. High-temperature storage stability, indirect tensile tests, and semicircular bending tests were conducted at medium and low temperatures. The results show that the bitumen modified with rubber powder has low stability, and this phenomenon is further intensified by an increase in the percentage of rubber powder. It was also shown that by adding a small percentage of sulfur to the bitumen modified with rubber powder, the storage stability of the prepared bitumen could be significantly improved. According to the tests conducted, the modification of bitumen with rubber powder leads to an increase in indirect tensile strength and the critical strain energy release rate at intermediate temperatures. It also improves the cracking properties of the asphalt mixture at low temperatures, thereby increasing fracture energy. The improvement of asphalt mixture properties increased with the rising percentage of rubber powder; however, it resulted in a weakening of the storage stability of the modified bitumen. The addition of a crosslinking agent resulted in higher cracking resistance in asphalt mixtures containing bitumen modified with rubber powder, based on the results of fracture mechanics tests.