The effects of freeze-thaw cycles and deicer salt on the durability of recycled asphalt mixtures
University of New Brunswick
In places with severe seasonal variations, such as the province of New Brunswick, asphalt mixtures are subjected to cyclic freezing and thawing during the cold months. Moreover, different types of deicers are frequently used to mitigate the effects of snow, ice, and freezing rain on the pavements to increase the safety of roadways. In partnership with New Brunswick Department of Transportation and Infrastructure (NBDTI), seven different mix designs of plant-produced asphalt mixtures, including recycled and conventional hot mix asphalt, were collected from different projects across the province. These samples were subjected to different conditions simulating extreme weather in New Brunswick before conducting multiple tests including indirect tensile strength, semicircular bending, and abrasion resistance. It was found that freeze-thaw cycles (FTCs) resulted in a high reduction in the tensile strength of the asphalt mixtures; however, there was not any significant difference between tensile strength of conventional and recycled mixtures. Saturation of the samples in deicer salt brine prior to testing did not result in a significant effect on the tensile strength. Semicircular bending (SCB) tests found that the cracking potential of the samples almost doubled after exposing them to a single freezethaw cycle. Finally, abrasion resistance tests showed that conventional asphalt mixtures were more susceptible to abrasion compared to the recycled mixtures.