Effect of freeze-thaw cycle on performance of unsaturated emulsified asphalt cold recycled mixture

According to the actual of emulsified asphalt cold recycled mixture pavement in seasonal frozen area，the freeze-thaw cycle test is designed to explore the performance decay law of the unsaturated emulsified asphalt cold recycled mixture under freeze-thaw cycles. Through the emulsified asphalt cold recycled mixture with different number of unsaturated freeze-thaw cycle，emulsified asphalt cold recycled mixture of ultrasonic wave velocity，void fraction，freeze-thaw splitting strength，low temperature splitting strength and high temperature shear strength were determined，emulsified asphalt cold recycled mixture macro performance changes are analyzed. The micro morphology of the mixture under different times of unsaturated freeze-thawing cycle is observed by Scanning Electron Microscope （SEM）. The results showed that after 20 cycles of unsaturated freeze-thaw，the void ratio of the emulsified asphalt cold-recycled mixture increased by 1.06%，the ultrasonic wave speed decreased and the splitting strength decreased by 26.3%. Both high temperature performance and low temperature performance are greatly damaged. The cement hydration products at the interface between emulsified asphalt and cement mortar in the mixture structure are damaged from the outside to the inside by freeze-thaw cycles，the asphalt mortar peels off， the adhesion between asphalt and aggregate decreases， and the space structure between aggregates is gradually damaged， which eventually leads to the performance damage of unsaturated emulsified asphalt cold recycled mixture. © 2022 Editorial Board of Jilin University. All rights reserved.