In the field of highway construction, the application of styrene–butadiene rubber (SBR)-modified asphalt has gained popularity across different levels of road surfaces. A crucial aspect in ensuring the efficacy of this modification lies in the compatibility between SBR and the matrix asphalt. To address this, the current study utilizes molecular dynamics simulation as a technique. By establishing a model for the SBR-modified asphalt mixture, the research quantifies the compatibility level between the SBR modifier and the asphalt. The aim is to uncover the underlying mechanisms of compatibility between the SBR modifier and the base asphalt, ultimately contributing to the improvement of the storage stability of SBR-modified asphalt, which holds significant importance. The investigation began with the creation of models for both the base asphalt and the SBR modifier. A model for the SBR-modified asphalt blending system was then formulated based on these initial models. After undergoing geometry optimization and annealing procedures, the model attained its lowest energy state, providing a reliable basis for examining the performance of SBR-modified asphalt. The study proceeded to calculate solubility parameters and interaction energies of the system to evaluate the compatibility between the SBR modifier and the base asphalt at various temperatures. The analysis of these parameters shed light on the compatibility mechanism between the two components. Notably, it was found that at a temperature of 160 ℃, the compatibility was significantly enhanced. The findings were further corroborated through scanning electron microscope and rheological tests. The outcomes of this research offer theoretical guidance for the application of SBR-modified asphalt.

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.

As a plasticizer, vegetable oil can improve the compatibility between straw fibers and an asphalt matrix and promote the uniform dispersion of fibers, thereby improving the viscoelastic properties of the composite material. This paper selected three vegetable oils: tall oil, rapeseed oil, and palm wax. Through dynamic shear rheology tests, low-temperature bending beam rheology tests, contact angle tests, and infrared spectroscopy tests, the vegetable-oil-reinforced straw fiber modification was analyzed from different points of view. The research results show that palm wax significantly improves the high-temperature rheological properties of straw-fiber-modified asphalt but has a negative impact on low-temperature properties. Tall oil can most significantly improve the low-temperature rheological properties of straw-fiber-modified asphalt. Rapeseed oil has the most obvious effect in improving the adhesion and water damage resistance of straw-fiber-modified asphalt. In addition, the research shows that all three vegetable oils exist in the modified asphalt in adsorbed form, and no new compounds are generated. These research results provide theoretical guidance value for the application of straw-fiber-modified asphalt pavement in different environments.