Moisture susceptibility evaluation of Hot Mix Asphalt: combined effect of traffic and moisture

To date, most of the studies to evaluate moisture susceptibility of hot mix asphalt have been carried out by quantifying the degradation of the mix properties due to conditioning that simulates the action of moisture in the field. There is a need for research on the identification of moisture susceptible mixes which show the material loss in the wheel-path under the combined action of traffic and moisture. The objective of this study was to simulate and analyze the moisture induced material loss, and also to identify a mix with the potential of moisture induced material loss that has shown damage in the field but not under regular testing in the laboratory. The Moisture Induced Stress Tester (MIST), Ultrasonic Pulse Velocity (UPV), Dynamic Modulus in Indirect tensile mode, Indirect Tensile Strength (ITS), and Model Mobile Load Simulator (MMLS3) tests were utilized in the study. The effluent from the MIST was checked for the gradation of dislodged aggregates and the Dissolved Organic Carbon content. The results from the effluent analysis showed the loss of material and aggregate breakage from a moisture susceptible mix. A similar type of losses from the mix was also evident from MMLS3 loading under wet-hot conditions. The results of the mix mechanical properties showed that the use of MIST in combination with UPV or ITS is ab le to identify moisture susceptible mixes, in particular for mixes with the potential of aggregate breakage.