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5 Web-Survey Results A follow-up web-survey of state DOTs and contractors to the one conducted in NCHRP Project 9-49 was performed in this project to identify WMA pavements with mix design and/or quality assurance (QA) data included in the flow chart for minimizing moisture susceptibility. The list of agency rep- resentatives and contact information was compiled from the information used in NCHRP Project 9-49 with updates from the current AASHTO Subcommittee on Materials roster and input from the NCHRP Panel. The survey covered topics including: (1) availability of moisture susceptibility laboratory data (mix design and QA) for specific WMA pavements, (2) moisture susceptibility crite- ria in mix design and QA, (3) field performance for available WMA pavements, (4) WMA technology and materials (includ- ing any anti-stripping additives) used in available pavements, and (5) willingness to participate further in this project. The detailed survey questions are documented in Appendix A. The web-survey was launched in October 2014 with an invitation e-mail containing a brief description of the objectives of the project and the purpose of the survey. The invitation was sent to DOT representatives from 50 states. In total, 41 responses were received (i.e., an 82 percent response rate), and the results are summarized by question in Figures 2 through 9. According to the survey results, WMA was used routinely in the majority of the states that provided a response (i.e., 88%), and the most common WMA technologies were Evotherm and foaming. With regard to the use of anti-stripping agents, 40% of the states that provided a response indicated that they did not require their use, while 60% indicated they did require the use of anti-stripping agents for various reasons such as aggregate type, on foamed mixtures, on all mixtures, or based on laboratory test results. The majority of the DOTs (i.e., 90%) reported having a standard or specification including moisture susceptibil- ity testing as part of the mix design and construction QA procedures, 12% indicated that the standard or specifica- tion was different for mix design and construction QA, and only 10% stated they did not have a standard or speci- fication for moisture susceptibility testing. The predominant standard used for moisture susceptibility testing was AASHTO T 283 or a modified version of it with 50% of the respon- dents indicating these two choices; only 8% indicated the use of AASHTO T 324 HWTT as the standard or specifica- tion for moisture susceptibility. Accordingly, the moisture susceptibility test that was prescribed with more frequency was TSR with 58% of the responses. HWTT was the second most used with 21% of the responses, and the rest were other tests such as the immersion-compression test or the boil test. With regard to WMA pavement performance, more than 90% of the states that provided a response indicated that no moisture-related distress had been observed to date on any of their WMA pavements with a range of pavement age from 3 to 8 years (5- and 6-year old pavements were pre- dominant). Of the states that noted moisture susceptibility issues, the possible cause of failure (especially for early fail- ures) was indicated to be the type of aggregate (i.e., gravel, sandstone, and granite), although the states clarified that these types of failures were not limited to WMA pavements but also occurred in HMA. The majority of the survey respondents indicated having moisture susceptibility data available either from mix design, construction, or production data. A few offered technical reports and papers on trial/research WMA sections. In addi- tion, about 55% of the states that provided a response indi- cated having upcoming projects and their willingness to share information about mix design, construction, materials and/or field performance monitoring. C H A P T E R 3
6Figure 2. Question 2: To what extent does your organization utilize WMA? WMA Technologies Other 11%Aspha-Min® 3% Terex® 6% Sasobit® 7% Advera® WMA 9% Aquablack 6% Rediset 7% Cecabase® RT 4% SonneWarmix 4% AquaFoam 3% Accu-Shear 4% Ultrafoam GX 6% Evotherm 16% Foaming 14% (a) Evotherm Types Other 13% Unknown 10% M1 17% DAT 20% 3G 40% (b) Rediset Types Unknown 6% RT 6% LQ 53%WMX 35% (c) Figure 3. Question 3: What types of WMA technologies does your organization use? Figure 4. Question 4: Does your organization require the use of anti-stripping agents with WMA?
(a) (b) Figure 5. Question 5: Does your organization have a standard or specification that includes moisture susceptibility laboratory testing as part of the mix design procedure or construction QA? Figure 6. Question 6: What moisture susceptibility test(s) is (are) included in the standard/specification? Figure 8. Question 8: Does your organization have laboratory test results (IDT, TSR, MR, or HWTT) or other information relevant to the moisture susceptibility guidelines proposed in NCHRP Project 9-49 that can be made available to the researchers conducting this study? Figure 9. Question 9: Does your organization have upcoming WMA projects and is willing to participate in NCHRP Project 9-49B by sharing information about mix design, construction, materials, and/or field performance monitoring? Figure 7. Question 7: Have any the WMA pavements in your state experienced premature or extensive moisture-related distress? (b)(a)
