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From page 23... ... 23 This chapter summarizes the responses received to the survey questionnaire sent to voting state DOT members of the AASHTO COMP. The members of this committee include representatives from the 50 states, the District of Columbia (DC) Read the entire page →
From page 24... ... 24 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Responded 50 No Response 2 Figure 7. State DOTs' and the District of Columbia's participation in the survey (plus Ontario, not shown on map; 50 respondents) Read the entire page →
From page 25... ... Survey Results: State of the Practice 25 situations: first, those designed for interstate and primary highways with very high traffic and second, for those mixtures that have at least 40% of total aggregate composed of quartzite, granite, or siliceous aggregate or that have at least 25% of aggregate coarser than #4 sieve (4.75 mm) Read the entire page →
From page 26... ... 26 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements 100-mm-diameter specimens for both field cores as well as for laboratory-prepared specimens, and reduces the conditioning time (shortens the procedure) for loose mixtures. Read the entire page →
From page 27... ... Survey Results: State of the Practice 27 used in mix design evaluations, a maximum rut depth of ≈0.5″, rather than a minimum SIP, was often used as an indicator of moisture susceptibility. As shown in Figure 11, a nearly equal number of state DOTs either followed the standardized moisture-susceptibility test method, or used a state-modified version of a standardized test. Read the entire page →
From page 28... ... 28 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Figure 12 shows the responses to the question about percentage of mixes that failed testing criteria during the mix design approval stage (Q2d) Read the entire page →
From page 29... ... Survey Results: State of the Practice 29 (creep-related) and the second (stripping-related) Read the entire page →
From page 30... ... 30 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Table 4 shows the responses received regarding the required test procedures to assess moisture susceptibility of mixtures during the acceptance stage (Q3a) Read the entire page →
From page 31... ... Survey Results: State of the Practice 31 To explore the possibility that some states use modified parameters of a standardized test method for acceptance purposes, Q3c asked the respondents to list these modifications, if their state DOT has adopted modified parameters/procedures. These modifications are tabulated in Appendix B Read the entire page →
From page 32... ... 32 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements their agency Project Special Provisions, while Texas DOT did not respond to this question. e remaining ve state DOTs that require HWTT for acceptance but do not have a minimum SIP requirement for acceptance are California, Idaho, Louisiana, Massachusetts, and Washington. Read the entire page →
From page 33... ... Survey Results: State of the Practice 33 Yes, for all mixtures 18 (36%) Yes, for certain mixtures or materials (aggregate) Read the entire page →
From page 34... ... 34 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements accomplished by means of a conventional screw conveyer. Colorado DOT allows all four additions mentioned in the survey, that is, addition to moist aggregate, addition to aggregate in the pugmill, injection into the drum, and introduction in the form of a HL slurry. Read the entire page →
From page 35... ... Survey Results: State of the Practice 35 Among the respondents, the use of anti-stripping additives based on rock types alone was never the sole option for any state DOT, nor was it based on trac volume alone. A few DOTs require its use in specic layers, such as: permeable asphalt treated bases (Delaware DOT) Read the entire page →
From page 36... ... 36 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Test, respectively. A complete list of other mitigation measures employed by various state DOTs is presented in Appendix B Read the entire page →
From page 37... ... Survey Results: State of the Practice 37 versus unconditioned samples are being considered by four and three DOTs, respectively (Figure 25) Read the entire page →
From page 38... ... 38 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements DOTs that (a) have conducted or sponsored research (past or on-going) Read the entire page →
From page 39... ... Survey Results: State of the Practice 39 eld performance related to moisture damage, and (c) construction or quality assurance procedures to prevent moisture damage. Read the entire page →
From page 40... ... 40 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements • Other additive agents and mitigation procedures mentioned by the respondents in connection with addressing the issue of moisture susceptibility of HMA mixtures included the use of silicone and polymer-based additives, mix marination, and allowing the contractor, in some cases, to select their own method to reduce moisture susceptibility. • In addition to the test methods mentioned, some DOTs also adopted other measures to mitigate moisture damage. Read the entire page →

From page 23...

... 23 This chapter summarizes the responses received to the survey questionnaire sent to voting state DOT members of the AASHTO COMP. The members of this committee include representatives from the 50 states, the District of Columbia (DC)