Chemo-mechanical deterioration and erosion mechanisms of asphalt materials exposed to complex mine roadway water: combined effects of acidity, alkalinity and salinity

Asphalt mixture is widely used in highway pavements, and has recently found gradual application in underground coal mine roadways. However, coal mine roadways contain various complex water types that affect asphalt pavement performance to varying degrees. This study investigated the erosion effects and mechanisms of four representative mine roadway waters on asphalt and asphalt mixtures. DSR, MSCR, BBR, and BBS evaluated the rheological and bonding properties of asphalt, and Marshall tests analyzed mixture mechanical degradation. FTIR and SEM were employed to characterize microstructural changes and reveal erosion mechanisms. Results show that the acidity, alkalinity, and salinity of mine roadway water collectively influence the rheological properties of asphalt. Roadway water weakened asphalt–aggregate bonding and altered interfacial failure modes: acidic/high-salinity water mainly reduced asphalt cohesion, whereas alkaline water caused more severe adhesion damage. With prolonged immersion, the Marshall stability and water stability of asphalt mixtures gradually decreased, and acidic roadway water caused the most evident mixture-level deterioration. FTIR and SEM confirmed mine water accelerated asphalt aging via oxidation, dissolution and crystallization damage, inducing chemical structural changes and surface degradation. This study provides theoretical and practical support for the safe, durable application of asphalt pavements in underground coal mine.