Study on the Performance of Asphalt Mixture Modified by Coal Gangue Surface

Abstract

This study evaluates the feasibility of employing waste coal gangue as a coarse aggregate in asphalt mixtures. Surface treatment of coal gangue aggregate with a methyl sodium silicate solution was implemented and the most effective modification scheme was established. Laboratory experiments examined how different gangue dosages and surface modifications influenced the road performance of coal gangue–asphalt mixtures. The findings reveal that although coal gangue performs worse than natural aggregate on certain metrics, it remains suitable for use in asphalt mixtures within the limits prescribed by relevant standards. The sodium methyl silicate treatment applied for 6 h produced the most favorable modification effect, markedly reducing water absorption while increasing density and improving the crushing value of coal gangue. Asphalt mixtures containing up to 30% coal gangue satisfied specification performance requirements, and permissible gangue content can be raised following surface modification. SEM observations indicated that surface pores and cracks in the coal gangue asphalt mixture were diminished after treatment, and micro-scale damage under high-temperature immersion and freeze–thaw cycling was alleviated.