Investigation of water phases on freeze–thaw damage on asphalt mixture by using information entropy

Water causes freeze and thaw (F–T) damage on asphalt pavement, and the extent of such damage varies with the water phase. This study describes the F–T damage evolution of asphalt mixtures in different water environments by introducing image information entropy, a method that can clearly describe the damage stage. Three F–T test procedures under different water conditions are designed. X-ray CT is used to obtain the internal images of mixtures under various F–T cycles. The information entropy during liquid water F–T procedure shows a three-stage variation, but vapour water procedure shows one-stage variation, indicating that the promoting effect of liquid water on F–T damage is significant. The amount of liquid water in the void affects the evolution rate of F–T damage. Moreover, the F–T damage is more sensitive to full water immersion conditions and the damage of OGFC is more severe in any water conditions compared with AC and SMA.