Enhancing rheological properties and self-healing performance of asphalt mastic using coal gasification slag

This study examines the possibility of employing coal gasification slag as filler to improve rheological behavior and self-healing efficiency of asphalt mastic. Coarse slag (CS) and fine slag (FS), two slag variants, were evaluated as alternatives to limestone filler (LF) at replacement ratios of 10 %, 20 %, 30 %, 40 %, and 50 % with particle size smaller than 0.075 mm. A comprehensive analysis was conducted using various methods: X-ray diffraction (XRD) to characterize mineral compositions, dynamic shear rheometer (DSR) to analyze the high-temperature performance, bending beam rheometer (BBR) to assess low-temperature behavior, and vector network analyzer system (VNA) to examine electromagnetic parameters. Furthermore, the initial temperature of self-healing and its healing capability were assessed. The outcomes revealed that both CS and FS effectively enhanced the capability to resist high-temperature permanent deformation of asphalt mastic while having a minor negative impact on low-temperature behavior. CS and FS substantially affected the flow behavior of asphalt and increased the initial healing temperature. Moreover, coal gasification slag significantly improved the crack-healing ability of the asphalt mastic, although excessive FS content could reduce these advantages. Optimal self-healing properties were achieved with asphalt mastic containing 50 % CS or 40 % FS. Electromagnetic testing revealed that CS and FS exhibited higher electromagnetic impedance compared to LF, enabling more efficient conversion of microwave radiation energy into thermal energy. Cost analysis results demonstrated significant financial benefits from the implementation of this utilization process. In general, this study highlights a promising approach to improving asphalt mastic performance while providing an innovative and sustainable method for recycling coal gasification slag, contributing to efficient waste utilization.