An increased potential for moisture damage and rutting has been the two main problems with warm mixed asphalt (WMA) implementation. The use of high reclaimed asphalt pavement (RAP) contents (25% or more) in WMA may alleviate these problems. At present, susceptibility to the moisture damage and rutting are usually tested for independently; however, these distress mechanisms can be linked for in-service pavements. An enhanced loaded wheel tracking test performed on dry and wet specimens, the PURWheel, is investigated in this paper to evaluate the interaction of traffic and moisture. The PURWheel is also compared with conventional rutting and moisture damage tests. PURWheel results are used to evaluate the performance of 25% and 50% RAP-WMA. Rutting and moisture susceptibility of the high RAP-WMA was comparable with current practice low RAP content hot mixed asphalt.

The results from accelerated pavement testing on warm-mix asphalt (WMA) mixtures designed for airfield pavements are presented. Three WMA mixtures and one hot-mix asphalt (HMA) mixture produced in an asphalt plant were evaluated under simulated heavy aircraft traffic. The evaluation was conducted at extreme traffic conditions, including heavy aircraft loading, high tire pressure, and high pavement temperature. Pavement structural response and rutting were evaluated to assess the susceptibility to permanent deformation of WMA mixtures compared with that of HMA produced with the same aggregate blend. Test results indicated that WMA was a viable product for surface mixtures on airfield pavements.

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This paper presents the results of tests of warm-mix asphalt (WMA) mixtures designed for airfield pavements. The study was conducted in two phases. The first phase included laboratory tests on 11 WMA technologies. The tests in Phase 2 were performed on three WMA mixtures and one hot-mix asphalt (HMA) mixture produced in an asphalt plant. The evaluation included performance tests to assess WMA susceptibility to permanent deformation and moisture damage compared with that of HMA produced with the same aggregate blend. Test results indicated that WMA potentially was a viable product for surface mixtures on airfield pavements. Although WMA exhibited poorer performance than HMA in moisture damage tests on laboratory-produced specimens, the plant-produced mix indicated little difference compared with HMA. Rutting potential for WMA was somewhat greater than for HMA for mixtures produced both in the laboratory and in an asphalt plant according to asphalt pavement analyzer and Hamburg wheel tracking tests. Differences in performance of WMA mixtures were not attributed to a specific WMA technology category. Variations in performance test results between laboratory-produced specimens and plant-produced specimens were noted and indicated a need to require performance testing as part of a comprehensive quality assurance plan.

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Durability of dense-graded asphalt (DGA) is a key issue with regards to long term pavement performance. There is a need for a practical and implementable test to estimate these parameters. Previous research has suggested that the Cantabro abrasion loss test has potential for this application. Both the development of the Cantabro method and its conventional application to open-graded friction course (OGFC) mixtures are reviewed. A four component research approach was undertaken to evaluate suitability of the Cantabro test for DGA mixtures that included testing of 438 specimens from 69 different mixtures. First, sensitivity of the test was assessed using a large range of typical Mississippi DGA mixtures. Second, variability of the test was measured by evaluating data sets with thirty replicates. Third, the effects of oven conditioning protocols were measured. Fourth, the effects of varying reclaimed asphalt pavement (RAP) contents were measured for warm-mix asphalt (WMA). The overall recommendation from the research was that the Cantabro test be given serious consideration for use as a durability measurement tool for DGA mixtures.

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The overall purpose of this paper is to identify the most reliable bulk mixture specific gravity (Gmb) measurement method for dense graded asphalt concrete that can be used for a wide range of air voids and specimen types. A secondary purpose is to identify ranges of conditions where less established Gmb measurement methods are suitable. A comprehensive literature review was performed to identify promising density test methods for further study. Findings from studies comparing AASHTO T166 (saturated surface dry method) and AASHTO T331 (Corelok method) were used to provide a succinct summary of the relative behaviors of the two methods at mix design, performance testing, and field construction air void levels. Density measurement was performed using four methods (AASHTO T166, T269, T331, and TP82) on dense graded mixture specimens. In total, approximately 2500 data points were used herein, with approximately 30 % of this total coming from literature review and 70 % coming from the authors of this paper. Review of literature along with the evidence presented in this paper indicates that T331 is the most reasonably accurate and versatile Gmb measurement method for a wide range of air voids all the way from mix design through performance testing to construction acceptance testing. T331 has also been recommended (or at least evaluated favorably) by several previous researchers over the last ten years. Based on the evidence presented in this paper, the provisional TP82 test method in its current form does not provide acceptable Gmb measurements relative to T166 or T331 over a wide range of air voids. The magnitude of the discrepancy begins to increase dramatically as air voids increase.