Appendix B Amplifying Questions

As part of our information gathering to better understand WMA processes and additives, the team desires to visit highway agencies and active construction projects, talk to contractors and suppliers of these projects, and review older existing projects for field performance.

1. What processes, materials, and construction practices are being used in the production and placement of warm-mix asphalt (WMA)? Expanded areas of interest include the following:
   • WMA additives and processes
   • Types of mixes using WMA (e.g., dense-graded, SMA, open-graded)
   • Use with polymer modifiers
   • Use with recycled or reclaimed asphalt pavement (RAP)
2. How do these processes, materials, and production practices differ from standard mix designs and production? Expanded areas of interest include the following:
   • Specifications
   • Differences in selection of aggregates, bitumen grade, or gradations
   • Laboratory testing
   • Moisture damage susceptibility
   • Workability
   • Asphalt plant setup and special equipment required
   • Production and placement temperatures
   • Tack coat and bond between layers
   • Placement and compaction
3. What are the performance characteristics of WMA in terms of rutting, fatigue cracking, thermal cracking, moisture damage, etc.? Expanded areas of interest include the following:
   • Comparisons with conventional hot-mix asphalt
   • Performance monitoring of in-place sections
   • Accelerated laboratory testing or test roads to evaluate performance
   • Failures or less-than-expected performance
   • Changes in products, practice, or specifications resulting from experience to date
4. What class of roadway or pavement, traffic volumes, and truck volumes are best suited for WMA use? Expanded areas of interest include the following:
   • Factors or criteria used to select particular projects
   • Use over concrete pavements
   • Experience with high-traffic-volume roads or airfields
   • Experience with low-volume roads
5. What are the benefits and future plans for using WMA? Expanded areas of interest include the following:
   • Studies documenting reduced emissions
   • Fuel savings
   • Studies documenting reduced worker exposure to fume
   • Cold-weather construction
   • Long hauls
   • Increased percentages of recycled asphalt pavement
   • Cost, cost-benefit analyses, or life-cycle cost analyses