Trends in Use of Millings in Pavement Maintenance

While millings materials from old pavement surface
can be an important component of cost effective maintenance
operation, their use in maintenance projects are not uniform and well
documented. This study documents the different maintenance
practices followed by four transportation districts of New Mexico
Department of Transportation (NMDOT) in an attempt to find
whether millings are being used in maintenance projects by those
districts. Based on existing literature, a questionnaire was developed
related to six common maintenance practices. NMDOT district
personal were interviewed face to face to discuss and get answers to
that questionnaire. It revealed that NMDOT districts mainly use chip
seal and patching. Other maintenance procedures such as sand seal,
scrub seal, slurry seal, and thin overlay have limited use. Two out of
four participating districts do not have any documents on chip
sealing; rather they employ the experiences of the chip seal crew. All
districts use polymer modified high float emulsion (HFE100P) for
chip seal with an application rate ranging from 0.4 to 0.56 gallons per
square yard. Chip application rate varies from 15 to 40 lb/ square
yard. State wide, the thickness of chip seal varies from 3/8'' to 1'' and
life varies from 3 to 10 years. NMDOT districts mainly use three type
of patching: pothole, dig-out and blade patch. Pothole patches are
used for small potholes and during emergency, dig-out patches are
used for all type of potholes sometimes after pothole patching, and
blade patch is used when a significant portion of the pavement is
damaged. Pothole patches last as low as three days whereas, blade
patch lasts as long as 3 years. It was observed that all participating
districts use millings in maintenance projects.

• Rafiqul Tarefder
• Mohiuddin Ahmad
• Mohammad Hossain

• Chip seal
• sand seal
• scrub seal
• slurry seal
• overlay
• patching
• millings.

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[2] MDT (2009). Maintenance Manual. Montana, USA.
[3] State of California Department of Transportation (2008). Maintenance
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[4] NCHRP (2005). Chip Seal Best Practices. Synthesis 342. Washington
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[6] WSDOT (2003). Asphalt Seal Coats. Washington, USA
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[11] IowaDOT (2014). Developmental Specifications for Hot Mix Asphalt
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[13] Web-3: http://www.azdot.gov/docs/default-source/materialslibrary/
item404h.pdf, consulted 19th June 2014.