Moisture sensitivity of asphalt mixtures under different load frequencies and temperatures

Effects of different parameters including aggregate type, asphalt mix design and construction, traffic and environmental conditions on moisture sensitivity of asphalt mixtures have been investigated by a large number of researchers. But, only a few researchers have reported combined effects of these parameters. The aim of the current study is to evaluate moisture sensitivity of asphalt mixtures under various environmental and traffic conditions and to assess their combined effect on permanent deformation. Dynamic creep test was carried out on the saturated and dry samples of asphalt mixtures made with dense graded aggregate to compare their permanent deformation behaviors in the presence and absence of moisture. The results of examining different temperature and loading combinations indicated that, at 40 °C with decreased frequency, the rate of increase in permanent deformation was more in saturated compared with the dry samples. Moreover, at this temperature, moisture had more detrimental effect compared with the temperature of 5 °C. Also, at 5 °C, the effect of moisture damage on the samples increased with the increase in frequency. According to the test results, the ratio of creep modulus to resilient modulus can be an appropriate indicator for evaluating moisture susceptibility at high temperatures.