Evaluation on moisture sensitivity of asphalt mixture induced by dynamic pore water pressure

Abstract

Moisture damage induced by dynamic pore water pressure commonly occurs in asphalt pavement with a service environment of frequent contact with liquid water. Dynamic water environment exhibits a different mechanism of moisture damage comparing with traditional static water immersion and freeze-thaw. The influencing factors of dynamic water environment mainly include the magnitude of pore water pressure, water temperature, and conditioning duration. This paper presents a study on evaluating and quantifying these factors’ degree of influence on moisture sensitivity of asphalt mixture using the orthogonal test and the gray correlation analysis method. A new method for moisture sensitivity evaluation was thus proposed based on dynamic water environment conditioning and uniaxial penetration strength test. Finally, the influence of materials’ properties on moisture sensitivity were further investigated. The results indicated that the ranking of factors impacting the indicator of fracture work density was water temperature, followed by pore water pressure and conditioning duration. A representative parameter combination of 60℃, 0.345 MPa, and 4000 cycles was thus recommended. It was found that dynamic water environment was harsher than static water immersion and almost equal to and even harsher than freeze-thaw. The indicator of fracture work density ratio, which took deformation feature of asphalt mixture into account, could well assess moisture sensitivity. Retained mechanical performance of water-conditioned asphalt mixture decreased with the increase of air void content. SBS modified asphalt binder significantly improved the resistance to moisture damage for asphalt mixture.