Effect of Moisture Damage on Material Properties and Fatigue Resistance of Asphalt Mixtures

Abstract

Dynamic mechanical analysis (DMA) has been used successfully to evaluate complex characteristics of fatigue damage and fracture of asphalt binders and mastics by measuring fundamental viscoelastic properties and damage characteristics. DMA was used to define the effect of moisture on fatigue damage and to concentrate on the fatigue damage susceptibility of the sand and asphalt mixture mastic fraction. Dynamic frequency sweep and time sweep tests were performed on cylindrical sand-asphalt samples in a dry state and after being subjected to moisture saturation. Test results clearly indicate that moisture reduces viscoelastic stiffness, fatigue resistance, and eventually fatigue life of sand-asphalt. The mechanistic role of moisture in fatigue was analyzed and quantified by using nonlinear viscoelastic theory based on pseudovariable concepts and a continuum damage fatigue model. The effect of material surface energies, which is strongly related to fracture and damage, is further discussed by using DMA fatigue test results and varying surface energy characteristics of individual mixture constituents. The DMA experimental procedure and analysis is an efficient way to identify the influence of moisture and to compare sand-asphalt mixtures in terms of moisture susceptibility.