Module 3-4

Cold Milling Cold Milling

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

Introduction Revolutionized HMA removal,

leveling and overlay preparation

Considerable changes over the last 20 years

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

Cold Milling Equipment

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

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

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

Design Considerations Resulting surface profile

Skid resistance

Pavement removal and surface profiling

Maintain bridge clearance and curb reveal

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

Construction Considerations How will grade be controlled?

Ski, string line, laser, other

Will ride quality be measured on the milled surface? Profilograph, profiler, none

Poor Milled Surface

Special Multiple Tooth Attachments

Special Multiple Wrap Drum

Review What are typical characteristics of

milling equipment?

Where is cold milling best applied?

What construction and design issues should you be aware of?

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.