Effects of silane coupling agent modified coal waste powder on performance of asphalt mortar and asphalt mixture

In view of the disadvantage that coal waste powder(CWP) can reduce the crack resistance of asphalt mortar at low temperature, silane coupling agent KH-550 was used to modify coal waste powder. The surface characteristics and modification mechanism of silane coupling agent modified coal waste powder were characterized by using Scanning Electronic Microscopy (SEM). Five kinds of silane coupling agent modified coal waste powder asphalt mortar with content 0%, 0.5%, 1.0%, 1.5%, 2.0% and limestone(LS) powder asphalt mortar were prepared under different filler-asphalt ratios, respectively. The effects and mechanism of silane coupling agent modified coal waste powder on the pavement performance of asphalt mortar and asphalt mixture was studied by the dynamic shear rheological test(DSR), low temperature bending beam rheological test (BBR), Brookfield viscosity test, adhesion test, Fourier Transform Infrared Spectroscopy (FTIR), rutting test, bending test at low temperature, immersion Marshall test and freeze-thaw split test. The results showed that the optimal proportion of KH-550 is 1.5% of CWP mass and CWP modified by silane coupling agent can greatly enhance high temperature performance, low temperature performance and adhesion of the asphalt mortar. Furthermore, CWP modified by silane coupling agent can significantly improve rutting resistance, low temperature crack resistance and water damage resistance of asphalt mixture.