Effects of Freeze–Thaw Cycles on Performance and Microstructure of Cold Recycled Mixtures with Asphalt Emulsion

Abstract

Although it is widely recognized that freeze–thaw cycles have a great influence on the properties of asphalt pavement, a quantitative understanding of how freeze–thaw cycles affect cold recycled mixtures with asphalt emulsion (CRME) is so far still lacking. The main objective of the paper was to investigate the performance and microstructure of CRME under freeze–thaw cycles with different water saturation conditions. For this, air voids, high-temperature stability, low-temperature cracking resistance, and moisture susceptibility of CRME were analyzed based on laboratory tests. The micro-morphology and chemical composition of cement asphalt emulsified compound mortar were observed by scanning electron microscopy (SEM). Results showed air voids of CRME increase as freeze–thaw cycles increase; the high-temperature stability, low-temperature cracking resistance, and moisture susceptibility of CRME decrease as freeze–thaw cycles increase; the asphalt strips from the surface of hydration products, and the composite structure mainly consists of hydration products as freeze–thaw cycles increase; the microstructure of CRME is destroyed. The freeze–thaw cycles have a negative effect on the CRME performance and microstructure.