Abstract: To extend the application of acidic aggregates in hydraulic asphalt concrete, this study uses organic anti-stripping agents (OA and OB) and inorganic anti-stripping agents (cement and hydrated lime) to increase the adhesion between acidic aggregates and asphalt. We conduct a laboratory experiment to evaluate the influence patterns of anti-stripping agents on the performance of asphalt and mixtures, through a series of tests including Fourier transform infrared spectroscopy (FTIR), conventional asphalt properties, rolling thin film oven aging (RTFOT), contact angle measurement, and water stability test. The results indicate abundant phosphate esters and aromatic components in the OA anti-stripping agent are key agents responsible for enhancing adhesion and thermal stability, respectively, as revealed by the infrared spectroscopy. Compared with OB, OA-modified asphalt is superior in anti-aging properties. At a dosage of 0.4%, the softening point after aging increases by only 0.5 °C for OA-modified asphalt, while by 3.4 °C for OB-modified. Surface energy tests demonstrate that increasing OA content improves the cohesive work, dry adhesive work, and water damage resistance index (R-value) of asphalt. For asphalt concrete, adding OA alone will reduce the splitting strength and stiffness modulus, and 100% cement replacement of mineral powder will restore the splitting strength to the baseline level while maintaining the stiffness modulus at 90% of the reference. In summary, the strategy of combining 0.4% OA organic anti-stripping agent with 100% cement filler significantly improves adhesion and water stability between asphalt and acidic aggregate, while maintaining good mechanical properties. The findings imply a feasible technical pathway for cost-effective utilization of the acidic aggregates in hydraulic engineering.

Key words: asphalt concrete, anti-stripping agent, acidic aggregate, adhesion, water stability