Evaluation of moisture damage within asphalt concrete mixes

Pavements are a major part of the infrastructure in the United States. Moisture damage of these pavements is a significant problem. To predict and prevent this kind of moisture damage a great deal of research has been performed on this issue in past. This study validates an analytical approach based on surface energy aimed at assessing moisture damage. Two types of bitumen and three aggregates are evaluated in the study. The two types of bitumen represent very different chemical extremes and the three aggregates (a limestone, siliceous gravel, and granite) represent a considerable range in mineralogy. Moisture damage was monitered as a change in dynamic modulus with load cycles. The analysis demonstrates the need to consider mixture compliance as well as bond energy in order to predict moisture damage. Mixtures with the two types of bitumen and each aggregate with and without hydrated lime were evaluated. The hydrated lime substantially improved the resistance of the mixture to moisture damage.