Resistance to Moisture-Induced Damage of Asphalt Mixtures and Aggregate-Binder Interfaces

Abstract

The aggregate-asphalt binder adhesiveness is considerably affected by moisture. This property may accelerate distresses in asphalt pavement surface courses when aggregate-binder compatibility is not adequate. Numerous tests have been developed to measure this property, such as the Moisture-Induced Damage test (AASHTO T283) and the Asphalt Bond Strength test (AASTHO TP 91). The former measures the indirect tensile strength of dry and moisture-conditioned asphalt mixtures. The latter measures the tension stress needed to remove a pullout stub with asphalt binder from a solid substrate. Although these are distinct tests, both may be used as a means to analyze how moisture affects a certain combination of mineral aggregate and asphalt binder. The objective of this work is to correlate the results of these two tests and to analyze if the tested combinations of materials follow the same trend under both circumstances. Chemical compositions of the tested aggregates are also investigated. Results from Moisture-Induced Damage tests show that the use of an antistripping agent may reduce the impact of moisture-damage on tensile strength and that the aggregate with a higher content of calcium oxide performed better. The 12 h moisture conditioning in the Asphalt Bond Strength test had a strong correlation with the dry mixes, which was not noticed for the mixtures conditioned for 3 and 6 h. Asphalt mixture’s moisture sensitivity results correlated well to the loss of adhesion in the aggregate-binder interface.