Performance and Verification of High-Modulus Asphalt Modified by Styrene-Butadiene-Styrene Block Copolymer (SBS) and Rock Asphalt

High asphalt grade and poor high-temperature performance are the primary reasons for the permanent rutting deformation of asphalt pavement. However, the low grade of asphalt and the poor low-temperature performance and fatigue life of the mixture can easily lead to the low-temperature cracking of asphalt pavement. With the rapid increase in road traffic, volume, and traffic load, the performance requirements of road asphalt materials are becoming higher and higher. High-modulus asphalt has excellent temperature stability and good fatigue resistance. However, high-modulus asphalt is expensive, so its use can greatly increase the pavement cost, restricting its wide application in road engineering. It is necessary to find an economical way to produce modified asphalt to meet the current road requirements. The aim of this study is to investigate the effects of styrene-butadiene-styrene block copolymer (SBS) and rock asphalt on the road performance of modified high-modulus asphalt, in which the replacement level of SBS and rock asphalt below 8 wt.% are compared. Apart from the conventional performance measurements, such as softening point, penetration, ductility and viscosity, thermal storage stability and rheological properties are also measured. The test results show that the composite modification of SBS and North American rock asphalt can effectively improve the high-temperature resistance and reduce the temperature sensitivity of 50# matrix asphalt, but it has no obvious improvement on its low-temperature performance. The preferred ternary blending system containing 4~6 wt.% SBS and 6~8 wt.% rock asphalt was obtained by performance analysis. It was verified that the performances of high-modulus asphalt mixture with the ternary blending asphalt above all meet the requirements of high-modulus asphalt mixture performance index.