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67 A P P E N D I X B Industry Survey Questionnaire The Transportation Research Board is preparing a synthesis on the Impact of Asphalt Materials Lift Thickness on Pavement Quality. Your cooperation in completing this survey, which is part of the information gathering on this topic, will be greatly appreciated. There are ten main questions in the survey, most of which only require clicking on the appropriate response(s). Some answers will lead to follow-up questions for clarification or additional information. We estimate the survey will take 15 minutes or less to complete. Click on >> to move forward and << to move backwards through the survey. In this survey, NMAS means nominal maximum aggregate size (one sieve size larger than the first sieve to retain more than 10%) as defined in AASHTO M 323. Fine mixes are those whose gradation passes above the primary control sieve, according to AASHTO M 323. Unless otherwise specified in the question, please base your answers on the state where you most commonly work. Please complete this questionnaire by March 16, 2018. If you prefer, you may respond to these questions using the PDF attached to the email invitation; this can be returned to Rebecca McDaniel, the consultant for this project, by email at email@example.com. If you have any questions about the survey, you may contact Dr. McDaniel by email or by phone at 765/463-2317 ext 226. Thank you! BACKGROUND INFORMATION Please provide your contact information so that we know who has completed the survey. Name Position/Title Company or organization Address City State Email Address Phone Number May we contact you for more information, if needed? o Yes o No o Contact this person instead Synthesis 49-05 Impact of Asphalt Lift Thickness â Industry Survey
68 Impact of Asphalt Thickness on Pavement Quality 1. In which states do you routinely work? o Alabama o Kentucky o North Dakota o Alaska o Louisiana o Ohio o Arizona o Maine o Oklahoma o Arkansas o Maryland o Oregon o California o Massachusetts o Pennsylvania o Colorado o Michigan o Rhode Island o Connecticut o Minnesota o South Carolina o Delaware o Mississippi o South Dakota o District of Columbia o Missouri o Tennessee o Florida o Montana o Texas o Georgia o Nebraska o Utah o Hawaii o Nevada o Vermont o Idaho o New Hampshire o Virginia o Illinois o New Jersey o Washington o Indiana o New Mexico o West Virginia o Iowa o New York o Wisconsin o Kansas o North Carolina o Wyoming In which state do you most commonly work? o Alabama o Kentucky o North Dakota o Alaska o Louisiana o Ohio o Arizona o Maine o Oklahoma o Arkansas o Maryland o Oregon o California o Massachusetts o Pennsylvania o Colorado o Michigan o Rhode Island o Connecticut o Minnesota o South Carolina o Delaware o Mississippi o South Dakota o District of Columbia o Missouri o Tennessee o Florida o Montana o Texas o Georgia o Nebraska o Utah o Hawaii o Nevada o Vermont o Idaho o New Hampshire o Virginia o Illinois o New Jersey o Washington o Indiana o New Mexico o West Virginia o Iowa o New York o Wisconsin o Kansas o North Carolina o Wyoming 2. Are you aware of any established policies or guidelines regarding appropriate asphalt lift thicknesses relative to the nominal maximum aggregate size (nmas) of the mixture in any of the states in which you work? o Yes o No o Unsure If yes, how are these policies or guidelines enacted? (Please click all that apply.) o Pavement Design Manual o Design Memo o Specifications o Other (Please specify)
Industry Survey Questionnaire 69 3. How do you typically measure pavement density for quality control? (please click all that apply.) o Nuclear density gauge o Non-nuclear density gauge o Cores o Other o Not applicable/State measures 4. Have you observed more difficulty in obtaining required field densities since implementing the Superpave mix design system in the states where you work? o Yes, initially but less so now o Yes, continuing to be difficult o Yes, with certain mixes or applications o No o Unsure o Have not implemented Superpave If you selected Yes, initially but less so now: If the situation has improved, what changed? (Please click all that apply.) o State adjusted lift thicknesses o Density requirements have been revised o Finer mixes (gradation above primary control sieve, PCS) are now more common than coarse (below PCS) o Mix design parameters (gyration level, minimum binder content, etc.) have been revised o Smaller NMAS mixtures are used in certain lifts (ex., 9.5 mm instead of 12.5 mm) o Other (please specify) If you selected Yes, continuing to be difficult, or Yes, with certain mixes or applications: Have you observed any increased difficulty obtaining adequate density in mixtures with these components or in these applications in any of the states where you work? (Please click all that apply.) o Reclaimed asphalt pavements (RAP) o Recycled asphalt shingles (RAS) o Polymer-modified binders o Ground tire rubber (GTR) o Certain binder grades (please specify grades) o Highly angular aggregates o Certain aggregate types (please specify o Certain aggregate types (please specify) o Thin lifts o At low base or mix temperatures o When compacting asphalt over concrete o Other (please specify) 5. Do any of the agencies you work for allow the use of warm mix asphalt technologies at conventional temperatures as a compaction aid? o Yes o No o Permissive spec or not monitored If Yes or Permissive spec/not monitored: If you are allowed to use WMA as a compaction aid, how often do you use it in those states where it is allowed? o Always o Frequently o Sometimes o Never
70 Impact of Asphalt Thickness on Pavement Quality 6. Have you observed any asphalt pavement performance problems that are perceived to be related in whole or in part to inadequate compaction during construction? (please click all that apply.) o Post-construction densification (rutting) o Increased cracking o Increased permeability o Decreased durability o Shortened pavement service life o Need for increased maintenance o Other (please specify) 7. Have you encountered situations during project planning or construction where you have requested exceptions or waivers to the lift thickness requirements? o Yes o No If yes, in what situations would you consider requesting changes to the specified lift thicknesses? (Please click all that apply.) o Anticipated compaction issues o Smoothness requirements o Maintenance of traffic issues o Late season paving o Other (please specify) If yes, on past projects where you have requested exceptions, are you aware of any construction or performance issues that developed that may have been related in whole or in part to the lift thickness? o Yes, please specify o No 8. Have you had to change your mix designs, compaction or other processes to cope with compaction difficulties? o Yes o No If yes, what changes have you chosen to make and how successful would you judge them to be? Largely successful Marginally successful Not very successful Fining up the mix design Using less angular aggregates Other changes to the mix design Using warm mix as a compaction aid Increasing compactive effort (more rollers, more passes) Changing roller patterns, speed, distance from paver Changing types of rollers Use of intelligent compaction Use of thermal imaging Other (please specify)
Industry Survey Questionnaire 71 9. Do you see a need for additional research into any of the following? (please click all that apply.) o Field validation of recommended ratios of lift thickness to NMAS o Means of improving mix compactibility o Means of achieving adequate mat density o Improved test methods or technologies to ensure adequate compaction o Effects of mixture properties on compactibility o Other (please specify) 10. If you have any additional thoughts or information on your organizationâs experience with the effects of asphalt lift thickness on pavement performance, please describe briefly here or indicate if you are willing to be contacted for further information. This completes the survey. Thank you for your time and information. Survey results will be summarized and shared with all respondents.