Study on road performance of asphalt mixture based on surface modification of coal gangue

In order to solve the problem of coal gangue environmental pollution and the shortage of aggregate resources in road engineering, this paper studies the feasibility of using waste coal gangue as coarse aggregate of asphalt mixture. Through the physical and mechanical properties test, the difference between coal gangue and natural aggregate was compared and analyzed. The surface modification and strengthening treatment of coal gangue aggregate was carried out by using methyl sodium silicate solution, and the best modification scheme was determined. The influence of different content and surface modification on the road performance of coal gangue asphalt mixture was studied by laboratory test. With the help of scanning electron microscope test, the change characteristics of the microstructure of coal gangue asphalt mixture before and after surface modification were explored. The results show that although the indexes of coal gangue are inferior to those of natural aggregate, it can be used to prepare asphalt mixture within the scope of specification requirements. The modification effect of sodium methyl silicate solution with modification time of 6 h is the best, which can significantly improve the water absorption, density and crushing value of coal gangue. When the content of coal gangue is controlled within 30 %, the performance of asphalt mixture meets the requirements of the specification, and the amount of coal gangue in asphalt mixture can be increased after surface modification. After surface modification, the surface pores and cracks of coal gangue asphalt mixture are reduced, and the surface micro-damage under high temperature immersion and freeze-thaw cycle conditions is improved. • A coal gangue asphalt mixture with both solid waste pollution and stone shortage was developed. • The modification effect of 8 % + 6h sodium methyl silicate solution on the porosity of coal gangue is the best. • Surface modified coal gangue asphalt mixture can improve the water damage resistance of asphalt pavement.