Rheological properties of asphalt mortar with silane coupling agent modified oil sludge pyrolysis residue

The treatment of oil sludge pyrolysis residue is a difficult problem and results in low resource utilization rate. This paper investigated the performance of oil sludge pyrolysis residue modified by silane coupling agent used to replace mineral powder in asphalt mortar. Different dosages of silane coupling agent and filler-asphalt ratios were considered, and the modification effects and mechanisms of silane coupling agent on the rheological properties of asphalt mortar with oil sludge pyrolysis residue were analyzed. Firstly, the physical and chemical properties of oil sludge pyrolysis residue were explored by electron microscopy scanning and infrared spectroscopy. Then, the rheological properties of asphalt mortar were examined by three major indexes (asphalt mortar, rheological properties of asphalt mortar, and water boiling test) to investigate the effect of different dosages of silane coupling agent on the rheological properties of asphalt mortar of oil sludge pyrolysis residue. Finally, the microscopic interfacial properties and modification mechanism of oil sludge pyrolysis residue asphalt mortar modified by silane coupling agent were analyzed by electron microscopy and infrared spectroscopy tests. The results demonstrated that, the oil sludge pyrolysis residue presented a well-developed pore structure and can form strong adsorption with asphalt; After the modification by silane coupling agent, the high-temperature performance and adhesion performance of the oil sludge pyrolysis residue asphalt mortar were significantly improved, and the low-temperature performance was significantly optimized. The asphalt mortar modified by 1.5% silane coupling agent shows the best performance. Compared with mineral powder asphalt mortar, the creep properties of the modified asphalt mortar at −6℃, −12℃ and −18℃ is reduced by 9.6%, 7.5% and 2.5%, the rutting resistance factor at 64℃, 70℃, 76℃ and 82℃ isimproved by −8.4%, 2.9%, 3.8%, and 8.0%, and the mass-loss rate after boiling is reduced by 27.3%. The silane coupling agent makes the filler surface become rough, and have an activation effect to increase its porosity, improve the adsorption properties of oil sludge pyrolysis residue on the light components in asphalt. Therefore, a strong physical and chemical adsorption forms between the filler and asphalt, and thus improve the pavement performance of the modified asphalt mortar.