Dynamic testing of hot mix asphalt for moisture susceptibility assessment

Moisture sensitivity testing of asphalt mixtures is critical for ensuring performance expectations are met. Moisture susceptibility is most commonly tested using the modified Lottman test. The shift towards mechanistic design calls for the utilization of a more fundamental test to evaluate moisture damage. This paper studies the possibility of using the flow number test with different ways of analysis to study its applicability for moisture susceptibility evaluation. Sixteen field procured mixtures were subjected to four different modes of moisture conditioning: (1) unconditioned without water submersion testing, (2) moisture saturation with water submersion testing, (3) moisture saturation with freeze/thaw conditioning without water submersion testing, and (4) moisture saturation with freeze/thaw conditioning and with water submersion testing. These samples were subjected to flow number testing. The Ohio State Model for rutting analysis was used to analyze the results. The results were then compared to the results from the modified Lottman test. Using the flow number test setup and analyzing the results using the Ohio State Model showed good potential in predicting moisture susceptibility. The data showed good consistency but a comparison to field performance is needed to identify whether the results are correlated to field performance or not.