Study of the Effect of Mixing Temperature of LDPE-Modified AC-WC on Mixture Voids Using SEM and XRF Analysis

The demand for high-quality and sufficient quantities of road construction materials must be fulfilled to ensure optimal performance. Asphalt is one of the primary materials in road construction. The use of plastic waste as an additive in AC-WC mixtures is a promising alternative expected to enhance structural and functional performance, particularly with appropriate mixing temperatures. This study aims to evaluate the effect of adding Low-Density Polyethylene (LDPE) plastic on the void content of AC-WC asphalt mixtures, as well as their microstructural and chemical characteristics, using Scanning Electron Microscopy (SEM) and X-Ray Fluorescence (XRF) analyses. The wet mixing method was used with LDPE content variations of 0%, 0.25%, 0.5%, 0.75%, and 1%. The test results showed that LDPE addition increased the values of Void in Mixture (VIM), Void in Mineral Aggregate (VMA), and Void Filled Bitumen (VFB) compared to conventional mixtures. The highest values were obtained at 0.75% LDPE for VIM (4.77%) and VMA (16.50%), and at 0.25% LDPE for VFB (74.40%). SEM analysis revealed that LDPE content between 0.25% and 0.5% produced a more homogeneous mixture structure, while higher LDPE levels led to agglomeration that reduced void-filling effectiveness. Meanwhile, XRF results indicated that the main chemical components SiO2, Al2O3, CaO, and Fe2O3 remained relatively stable, confirming that LDPE is inert and does not introduce new heavy metal contaminants, making it environmentally safe. This study concludes that the addition of LDPE, within optimal limits, can enhance the structural performance of AC-WC mixtures and serves as a sustainable solution for utilizing plastic waste in road infrastructure development.