Long-term performance characteristics and interface microstructure of field cold recycled asphalt mixtures

This paper aims at investigating the long-term performance and interface microstructure of Cold Recycled Asphalt mixtures bound by emulsion (CRME) cored from field road serviced for 8 years, and the CRME prepared and cured in laboratory for 27 months are evaluated as reference. Firstly, air void and its distribution, indirect tensile strength and dynamic creep test is conducted to evaluate the performance of CRME. Then, microstructure of asphalt-cement mortar and fracture interface of CRME is observed and discussed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). The results indicate that indirect tensile strengths and creep deformation of field CRME can still meet the performance requirements after 8 years in service. Furthermore, lower air void, more C-S-H gel and less Ca(OH)(2) of hydrated products in cement-asphalt mortar is observed in interface of field CRME. In addition, the interface between cement-asphalt mortar and aggregates may be enhanced by traffic loading from microstructure analysis and performance test. The research may help to get better understanding on the long-term performance of field CRME. (C) 2020 Elsevier Ltd. All rights reserved.