1. Module 3-4 Cold Milling

2. Learning Objectives  Describe the cold milling process  Describe the characteristics of typical milling equipment  Describe typical applications of cold milling and where it is best applied  Describe design and construction issues

3. Introduction  Revolutionized HMA removal, leveling and overlay preparation  Considerable changes over the last 20 years

4. Definitions  Cold milling - removal of pavement surface using drum-mounted carbide steel cutting bits  Diamond grinding  Restore ride  Improve friction  Not to remove material  Grooving – resist hydroplaning

5. Cold Milling Equipment

6. Purpose and Application  Primary use on HMA  Overlay  Recycling  Reconstruction  Emerging use on PCC  Full lane to partial lane width  Partial depth to full depth removal

7. How does your State use cold milling?  Removal of rutting  Restoration of curb line  Restoration of cross slope  Restoration of surface friction  Mass removal of HMA  Roughened surface for improved bond between layers

8. Limitations and Effectiveness  Surface texture produced by milling is a function of:  Carbide bit spacing and condition  Depth of cut  Rotational speed of head  Speed of travel

9. Design Considerations  Resulting surface profile  Skid resistance  Pavement removal and surface profiling  Maintain bridge clearance and curb reveal

10. Construction Considerations  Pavement to be resurfaced  Standard head with normal carbide bits  Standard line and grade requirements  Pavement surface to be turned over to traffic  Special heads with more carbide bits  Smoothness and grade requirements in line with HMA wearing course

11. Construction Considerations  How will grade be controlled?  Ski, string line, laser, other  Will ride quality be measured on the milled surface?  Profilograph, profiler, none

12. Poor Milled Surface

13. Special Multiple Tooth Attachments

14. Special Multiple Wrap Drum

15. Review  What are typical characteristics of milling equipment?  Where is cold milling best applied?  What construction and design issues should you be aware of?

16. Key References  Collura, J., T. El-Korchi, K. Black, M. Chase, and L. Jin. 1997. Guidelines for Ride Quality Acceptance of Pavements, Final Report. New England Transportation Consortium, Worcester Polytechnic Institute, Worcester, MA.