Comparative analysis of aggregate gradation variation in porous asphalt mixtures under different compaction methods ¹

Abstract The insufficient skeletal stability of porous asphalt mixtures (PAM) stems critically from the poorly understood dynamic evolution of aggregate gradation during compaction. The differential impacts of distinct compaction methods remain inadequately characterized. This study systematically investigates the effects of Marshall Compaction (MC) and Superpave Gyratory Compaction (SGC) on gradation variation in PAM-13 and PAM-16, incorporating key parameters such as asphalt addition states and compaction energy levels. Specimens were prepared under both with asphalt and without asphalt conditions, subjected to multi-level compaction energy, and subsequently analyzed through sieve analysis. Key findings reveal that MC induces more pronounced coarse aggregate breakage (up to −15.06 %) and fine aggregate generation (up to 101.64 %); SGC better preserves fine aggregate integrity; asphalt provides protective effects predominantly for fine aggregates; and increasing compaction energy continuously exacerbates fine aggregate fragmentation. The findings elucidate the gradation variation patterns induced by different compaction methods, thereby providing a critical theoretical foundation for optimizing the design and construction control of PAM.