Rheological Properties and Performance Evaluation of Different Types of Composite-Modified Asphalt in Cold Regions

In low-temperature environments, asphalt materials harden easily and become brittle, and the repeated action of traffic load further aggravates the cracking of and damage to the asphalt mixture. In order to explore high-performance asphalt pavement materials that are more suitable for cold climates, this paper selected four modifiers, namely SBS, rubber powder, SBR and TPS. With SBS as the main agent, combined with other modifiers, three types of base asphalts with grades of 70#, 90# and 110# were compositely modified to prepare 12 different combinations of composite-modified asphalt samples. The optimal dosage of the modifier was determined by the basic performance test of asphalt, and the compatibility, interaction energy and mechanical properties of the modifier and base asphalt at different temperatures were analyzed by molecular dynamics simulation. Subsequently, the high- and low-temperature rheological properties of various modified asphalts were systematically evaluated using a dynamic shear rheology test (DSR) and a bending beam rheology test (BBR), and the rheological properties and road performance indicators of each composite-modified asphalt were comprehensively compared so as to select the road materials most suitable for cold areas. The research results show that different grades of base asphalt and modifiers show good compatibility in the range of 160–175 °C. Among them, rubber powder and TPS modifier significantly improve the high-temperature mechanical properties of SBS-modified asphalt, while rubber powder and SBR modifier significantly improve its low-temperature mechanical properties. The DSR and BBR test results further show that SBS/rubber powder composite-modified asphalt exhibits excellent rheological properties under both high- and low-temperature conditions, and is the preferred solution for road materials in cold regions.