Influence of surface treated fly ash with coupling agent on asphalt mixture moisture damage

Moisture damage is of great negative impacts on asphalt pavement. It exacerbates the service performance (e.g., rutting, cracking) for asphalt mixture under traffic load. This paper describes the influence of surface treated fly ash with silane coupling agent on asphalt mixture moisture damage. The filler combined with coupling agent and fly ash was named compound fly ash modifier (CFAM). Primarily the properties of CFAM were characterized by Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy. As filler, its effects on moisture sensitivity of asphalt mixture were evaluated by modified Lottman test, indirect tensile stiffness modulus test, static creep and indirect tensile fatigue test. It is shown that the asphalt mixture with CFAM has excellent moisture sensitivity in terms of higher indirect tensile strength and tensile strength ratio during frost–thaw process. In addition, after specific moisture damage treatments, CFAM modified asphalt mixtures show better stiffness modulus, resistance to permanent deformation and fatigue life. It is concluded that CFAM can improve the moisture sensitivity of asphalt mixture effectively.