Evaluating Moisture Susceptibility of Asphalt Mixes


Book Description

This research project utilized laboratory evaluations to study effects of freeze-thaw cycling on the tensile strength of eight Hot Mix Asphalt mixtures and to determine if the Georgia Loaded Wheel Tester could be utilized to measure moisture susceptibility of Hot Mix Asphalt mixtures. The evaluation involved eight Hot Mix Asphalt mixtures from combinations of two aggregate types and four asphalt-additive-aging possibilities. Laboratory testing was accomplished in the first phase with the production of 2.5 by 4 inch cores that were freeze-thaw cycled and tested for their indirect tensile strength following Wyoming modified AASHTO T283. The second phase was accomplished using 3 by 6 inch cores that were conditioned and tested for rutting using the Georgia Loaded Wheel Tester. Finally, a statistical analysis was performed to determine if performance of the various mixtures was significantly different in groups of asphalt types and to determine if the Georgia Loaded Wheel Tester was a viable measurement tool for moisture susceptibility.










Moisture Damage in Asphalt Concrete


Book Description

This synthesis will be of interest to pavement designers, construction engineers, maintenance engineers, and others interested in avoiding or limiting moisture damage in asphalt concrete. Information is provided on physical and chemical explanations for moisture damage in asphalt concrete, along with a discussion of current practices and test methods for determining or reducing the susceptibility of various asphalt concrete components and mixtures to such damage. Moisture damage in asphalt concrete is a nationwide problem which often necessitates premature replacement of highway pavement surfaces. This report of the Transportation Research Board describes the underlying physical and chemical phenomena responsible for such damage. Current test methods used to determine the susceptibility of asphalt concretes, or their constituents, to moisture damage are described and evaluated. Additionally, current practices for minimizing the potential for moisture damage are examined.










Evaluation of the Moisture Susceptibility of WMA Technologies


Book Description

"TRB's National Cooperative Highway Research Program (NCHRP) Report 763: Evaluation of the Moisture Susceptibility of WMA Technologies presents proposed guidelines for identifying potential moisture susceptibility in warm mix asphalt (WMA). The report also suggests potential revisions to the Appendix to AASHTO R 35, "Special Mixture Design Considerations and Methods for WMA" as a means to implement the guidelines."--publisher's description







Evaluation of Moisture Susceptibility of Asphalt Mixtures Using Dynamic Modulus


Book Description

A pothole is one of the distresses in asphalt pavement caused by the presence of water in the asphalt pavement and the presence of traffic passing over the affected area. Recently, lots of potholes were observed due to heavy rain in Korea. Thus, the indirect tensile strength ratio (TSR) is commonly used based on the AASHTO T 283 procedure to evaluate the moisture susceptibility of an asphalt mixture; however, TSR cannot be used as a representative index for the mechanical behavior of the moisture-conditioned asphalt mixture. In this study, the dynamic modulus |E*| laboratory test is applied as a replacement test for the TSR in order to assess the moisture susceptibility of four different asphalt mixtures. The dynamic modulus test is used to determine the % of retained stiffness, a term that was referred to as the dynamic modulus ratio (DMR). The results of both TSR and DMR conducted on the same mixtures are compared and statistically analyzed. The logistic regression model was used to evaluate the correlation between TSR and DMR. The correlation between TSR and DMR at 20°C is significant. However, there was no relation between TSR and DMR at other temperature ranges (5°C, 40°C, 54.4°C) because there was different viscoelastic behavior at different temperature.




Suitability of Dynamic and Relaxation Tests for the Evaluation of Moisture Susceptibility of Asphalt Mixtures


Book Description

The presence of waIn ter in asphalt pavements deteriorates their condition and causes distresses that result in high maintenance costs to state and federal agencies. The objective of this research was to execute dynamic and relaxation tests and evaluate their effectiveness in assessing moisture susceptibility of asphalt mixture specimens with different air void structures determined using X-ray computed tomography (CT) and conditioned using the modified Lottman procedure. The dynamic test consisted of the application of a sinusoidal cyclic compressive load on the specimen while maintaining the strain within a specified range. The relaxation test, performed in both direct tension and compression, consisted of the application of a constant static strain. A statistical analysis was used to study the effectiveness of the tests in evaluating the moisture susceptibility of the asphalt mixtures. The results showed that none of the tests (dynamic or relaxation) were consistent in differentiating between the moisture conditioned and unconditioned specimens or between the responses of the different mixtures within each condition. In addition, the results of the dynamic and relaxation tests were compared after applying different methods to convert frequency-domain data to time-domain data.