MOISTURE SENSITIVITY EVALUATION OF BINDER-AGGREGATE MIXTURES

Abstract

This study assessed the moisture sensitivity of several binder-aggregate mixtures. This assessment included an evaluation of the effect of hydrated lime on the moisture sensitivity of asphalt-concrete mixtures, the effect of variations from the optimum binder content on the moisture sensitivity of asphalt-concrete mixtures, the moisture sensitivity of asphalt-rubber mixtures, and the potential use of controlled-strain fatigue beam testing to evaluate the moisture sensitivity of asphalt-concrete mixtures. Four aggregates, three asphalt contents, and two hydrated lime contents were used for the asphalt-concrete mixtures. The asphalt-rubber mixtures included asphalt-rubber gap-graded and dense-graded hot mix. Tests performed included AASHTO T283 and the controlled-strain fatigue beam test (Strategic Highway Research Program A-003A). It was found that hydrated lime in a slurry form could be effective in reducing moisture sensitivity of asphalt-concrete mixtures. The degree of its effectiveness was found to depend on asphalt content, lime contnet, and aggregate source. Also, it was found that a reduction in the binder content by 0.5% from the optimum could adversely affect the resistance to moisture damage. AASHTO T283 results showed that the asphalt-rubber mixtures may be more sensitive to moisture than conventional dense-graded asphalt-concrete mixtures. The fatigue beam test results indicated that the test had a potential use in moisture-sensitivity evaluation. The potential parameters were the flexural stiffness ratio and the fatigue life ratio.