Study on the Performance Improvement of Straw Fiber Modified Asphalt by Vegetable Oil

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.