The Effect of Waste Low-Density Polyethylene/Plasticizer Diisononyl Phthalate on the Performance of Asphalt Binder

As an aspect of green road construction, the use of waste plastic agricultural film in asphalt pavement not only mitigates environmental pollution but also enhances the mechanical properties of asphalt. However, it has been plagued by problems such as poor low-temperature crack resistance and poor compatibility. To address this problem, this study used waste low-density polyethylene (LDPE), sourced from waste film, and the plasticizer diisononyl phthalate (DINP) to enhance the properties of asphalt. Based on orthogonal tests, rheological property tests, conventional property tests, storage stability tests, fluorescence microscopy (FM), and Fourier transform infrared (FTIR) tests, waste LDPE/plasticizer DINP-modified asphalt samples were evaluated. Orthogonal tests indicated that a modified asphalt optimum preparation process of 30 min and 4500 rpm at 180 °C was beneficial. Conventional and rheological property tests revealed that 4% waste LDPE modified with 2.5% plasticizer DINP represents the optimal combination to effectively enhance the low-temperature rheological properties of asphalt while exerting minimal impact on its high-temperature characteristics. Storage stability and FM analysis indicated that waste LDPE is evenly dispersed in the modified asphalt binder when 3% plasticizer DINP is added. FTIR analysis revealed no change in the absorption peaks after waste LDPE and plasticizer DINP were added to asphalt, indicating that no chemical reactions occurred. Overall, waste LDPE/plasticizer DINP-modified asphalt exhibits excellent rheological properties and storage stability, which are conducive to green road construction and resource utilization.