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A-1 A-1 Appendix A Worldwide Survey Questionnaire

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A-2 Worldwide Survey Questionnaire National Cooperative Highway Research Program Project 9-40 "Optimization of Tack Coat for HMA Placement" Questionnaire Tack Coat Materials 3. What type(s) of tack coat material is (are) typically applied to each of the following existing pavement 1. Which types and grades of asphalt binder materials are surfaces? commonly used for tack coat on your agency's asphalt paving projects? Tack Coat Dilution Application Residual Material Rate Rate Application Rate Emulsified asphalt Cutback asphalt Pavement Type Asphalt Type/ % Residual Type % Residual Type % Residual (ratio) (gal/yd2) (gal/yd2) cements Grade Asphalt Asphalt Asphalt Between new HMA layers On top of an existing HMA surface On top of a milled HMA surface On top of 2. How much (approximate percentage) of each of the a surface various materials listed in Question 1 was used in the treatment, seal coat, or past few years? chip seal Asphalt cements Emulsified asphalt Cutback asphalt On top of an Type/Grade % Type/Grade % Type/Grade % asphalt treated base course On top of an existing PCC surface On top of a milled or diamond- ground PCC surface

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A-3 Tack Coat Application Method 9. What is the maximum time that the tack coat can be exposed to traffic before it is covered by HMA mix? 4. If the emulsion material is allowed to be diluted, where Min _____ Hrs _____ Days _____ does the dilution process take place? a. At the asphalt supplier's terminal. ____ Yes ____ No b. At the contractor's storage tank. ___ Yes ____ No 10. How is the asphalt tack coat material commonly applied c. After the undiluted tack coat material is in the dis- on a mainline paving area? (Check all that apply.) ____ a. Asphalt distributor/Hand wand. Please specify tributor tank. ____ Yes ____ No % of use d. Other location. Please specify. _________________ ____ b. Asphalt distributor/Spray bar. Please specify e. None of the above % of use If dilution is not allowed, go to Question 7 ____ c. Spray bar attached to the paver. Please specify % of use ____ d. Others. Please specify. ___________________ 5. How is the dilution rate of an asphalt emulsion verified? (Check all that apply.) ____ a. Certification by the asphalt supplier. 11. Are the haul trucks permitted to drive over the asphalt ____ b. Certification by the contractor. emulsion tack coat material before it ____ c. Sample taken and tested from the contractor's a. Breaks? (Emulsion color changes from brown to storage tank. black). ____ Yes ____ No ____ d. Sample taken and tested from the distributor. b. Sets? (All water has evaporated from the pavement ____ e. Visual observation of the actual dilution of the surface). ____ Yes ____ No asphalt emulsion. ____ f. Use of ASTM D2995: Estimating Application 12. When is the paver permitted to place HMA over the Rate of Bituminous Distributors. applied tack coat? ____ g. None of above. ____ a. Immediately after it breaks (emulsion color ____ h. Others. Please specify. ___________________ changes from brown to black). ____ b. Immediately after it sets (all water has evapo- rated from the pavement surface). 6. How often is the diluted rate verified? ____a.Daily. 13. Rank the following factors that affect the break and set ____b.Monthly. time for an asphalt emulsion tack coat material. (1most ____ c. Project by project. important, 7least important) ____ d. Not checked. ____ a. Application rate. ____ e. Others. Please specify. ___________________ ____ b. Dilution rate. ____ c. Ambient temperature. ____ d. Pavement surface temperature. 7. Is traffic allowed on the tack coat materials prior to plac- ____ e. Wind velocity. ing the HMA mix? ____f. Humidity. ____a.No. ____ g. Others. Please specify. ___________________ ____ b. Yes. Please specify the minimum time re- quired prior to trafficking (Min, Hrs, Days). 14. What methods are used to prevent/minimize pickup of _____ Min _____ Hrs _____ Days the tack coat materials by the tires of the haul trucks? (Mark all that apply.) ____ a. The tack coat is required to be completely set 8. If the answer to Question 7 is "yes," is the minimum time before the haul trucks travel over the material. required prior to trafficking affected by the type of the exist- ____ b. The pavement surface is sanded after the tack ing pavement surfaces (i.e., "Between new HMA layers," coat material is applied. "On top of a milled HMA surface," "On top of an existing ____ c. The haul trucks travel over the emulsion tack PCC surface," etc.)? coat material before it breaks. ____a.No. ____ d. Pick up is a continuing problem. ____ b. Yes. Please specify. ______________________ ____ e. Others. Please specify. ___________________

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A-4 15. What percentage of the existing pavement surface area is ____ d. Proper angle of nozzles. typically covered with residual tack coat material? ____ e. Proper height of the spray bar and lap between ____ a. 100 percent. spray from adjacent nozzles. ____ b. 90 to 100 percent. ____ f. Not checked. ____ c. 70 to 90 percent. ____ d. 50 to 70 percent. 20. Does the tack coat residual application rate change due to ____ e. Less than 50 percent. any of the issues listed below? Yes ____ No _____ 16. Indicate which, if any, of the following are specified If "yes," it is due to requirements for application of tack coat material? ____ a. Time of year. ____ a. Amount of spray overlap between nozzles on Indicate how much the rate change is the distributor spray bar _____________ ____ single lap ____ double lap ____ triple ____ b. Type of roadway--interstate, primary, lap secondary roadway. _____ b. Angle of the nozzles to the axis of the spray bar Indicate how much the rate change is ____ (Min, degree) ____ (Max, degree) _______________ _____ c. Height of the spray bar above the pavement ____ c. Condition of roadway, i.e., aging, raveling, surface cracking, etc. ____ (Min, inches) ____ (Max, inches) Indicate how much the rate change is ____d.None ______________ ____ d.Ambient temperature. 17. What environmental restrictions are placed on the appli- Indicate how much the rate change is cation of the tack coat material? (Mark all that apply.) ______________ ____ a. Minimum ambient temperature __ C. ____ e. Daytime versus nighttime paving. ____ b. Maximum ambient temperature __ C. Indicate how much the rate change is ____ c. Minimum pavement surface temperature __ C. ______________ ____ d. Maximum pavement surface temperature __ C. ____ f. Traffic use before overlay. ____ e. Impending rainfall. Indicate how much the rate change is ____ f. Wet pavement surface. ______________ ____ g. Damp pavement surface. ____ g. Thickness of subsequent overlay. ____ h. Time of year (paving season). _____________ ____ i. Other. Please specify. ____________________ 21. If the tack coat application is not uniform, what steps are 18. How are the application rate and the residual tack coat taken to correct the problem? rate checked? ____ a. Remove the tack coat? If so, please specify ____ a. Use of ASTM D2995: Estimating Application how. __________ Rate of Bituminous Distributors. ____ b. Reapply the tack coat ____ b. Difference in weight of the asphalt distributor i. At the same application rate. over a set width and length. ii. At a lesser application rate. ____ c. Difference in the amount of material in the ____ c. Take a price deduction from the contractor. asphalt distributor tank ("sticking the tank") ____ d. Ask the contractor not to do it again. over a set width and length. ____ e. Required improved application on next pass. ____ d. Not checked. ____ f. Do nothing. ____ e. Other. Please specify. ____________________ Characterization of Tack Coat Application 19. What are the specified requirements for the uniformity of the applied tack coat material? (Check all that apply.) 22. In your experience, what type of pavement failure is ____ a. Total pavement surface must be covered with related to improper application or type of the tack coat tack coat material. material? (Check all that apply.) ____ b. Percentage of pavement surface covered with ____ a. Slippage of the surface course layer on top of tack coat material. the underlying layer. ____ c. No blocked or partially blocked nozzles on the ____ b. Delamination of the surface course layer from asphalt distributor. the underlying layer.

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A-5 ____ c. Fatigue cracking of the pavement structure. 25. Are you aware of any recently completed or on-going ____ d. Top-down cracking. research projects in your agency that related to the per- ____ e. Rutting of the pavement surface. formance of tack coat materials? ____ f. Other distress: _________________________ ____ a. Yes. Please specify. _____________________________ 23. What laboratory or field test methods do you used to ____b.No. determine the interface bond strength between layers? ____ a. Laboratory, please specify. 26. Please provide any additional comments. _____________________________ ____________________________________________ ____ b. Field, please specify. ____________________ ____________________________________________ ____________ ____________________________________________ ____c.None. ____________________________________________ ____________________________________________ 24. Beyond specification and bond strength requirements, ____________________________________________ are there any other field or laboratory tests used to evalu- ate the quality of tack coat materials? 27. I would like to be contacted by a member of the research ____ a. Yes. Please specify. team. ____________________________ ____a.Yes. ____b.No. ____b.No.