Optimization of Tack Coat for HMA Placement (2012)

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A-1 A p p e n d i x A Worldwide Survey Questionnaire

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

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

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

A-5 ____ c. Fatigue cracking of the pavement structure. ____ d. Top-down cracking. ____ e. Rutting of the pavement surface. ____ f. Other distress: _________________________ 23. What laboratory or field test methods do you used to determine the interface bond strength between layers? ____ a. Laboratory, please specify. _____________________________ ____ 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? ____ a. Yes. Please specify. ____________________________ ____ b. No. 25. Are you aware of any recently completed or on-going research projects in your agency that related to the per- formance of tack coat materials? ____ a. Yes. Please specify. _____________________________ ____ b. No. 26. Please provide any additional comments. ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ 27. I would like to be contacted by a member of the research team. ____ a. Yes. ____ b. No.