Deeper Hot-In-Place Recycled Asphalt Saves Money and Time

Item #: 20240045

CONTACTS

Implementing Organization: Region Three
Champion: Jason Simmons
Implementation Lead: Clayton Weaver
Development Team:

UDOT: Clayton Weaver, Jason Simmons, Jared Dastrup, Mike Blotter, Craig Hebbert

Dustrol Inc.: Doug Gordon

Burdick Materials: Tony Hickman

Sunrise Engineering (Drone imagery)

Article Written By: Craig Hebbert
Innovation Council Liaison: Craig Hebbert
Innovation Team Coordinator: Winston Inoway

STATUS

Implementation Date: June 1, 2022
Adoption Status: Fully Implemented
Adoptability Note: This is a useful tool that might be used in place of typical mill and fill projects.

APPLIES TO

Topic: Construction Practices
Organization(s): Central Admin / Senior Leaders, Central Construction, Central Maintenance / Facilities Management, Central Materials, Region 1, Region 2, Region 3, Region 4
Job Role(s): Construction Engineer, Materials Engineer, Transportation Technician
Tags: Highway transportation, infrastructure preservation, labor productivity, materials, expenses, expenditures, value of time, adoption, civil engineering, materials science, mechanical engineering, construction, inspection, maintenance, project management, testing > samples, sampling, pavement, environmental quality, pollution, air, noise, user benefits, value capture

PROBLEM

The previous hot-in-place recycle asphalt process using scarifying trucks was limited to addressing surface problems up to a maximum depth of 1.5”. On multiple routes, there were deep, environmental top-down cracks that could not be remedied with this process. These repairs required major rehabilitation or reconstruction that is expensive and has greater impacts (more time consuming).

CHANGE

UDOT has implemented a new deeper hot-in-place recycling process that has been used in other states in the south and midwest.

In this new process, the first two trucks in the train use heaters to heat the existing surface. The next truck mills off 1” of asphalt and places it in a windrow. Additional alternating heating and milling trucks are then used to remove an additional 0.5” at a time, until the desired depth is reached. The final truck adds and mixes a rejuvenating agent into the milled asphalt. A conventional paver is then used to pick up the windrow and place the recycled asphalt. It is then rolled and compacted as a typically hot mix asphalt.

RESULT

This new process enables UDOT to address and resolve deeper cracks without major rehabilitation or reconstruction, saving money and significantly reducing construction time.

The previous hot-in-place process used scarification (up to 1.5” deep) rather than milling (up to 3” deep) and had several other disadvantages. There were concerns the scarification process broke the existing aggregate, burned off oil/overheated the existing asphalt, and the depth of the hot-in-place process could not be verified during inspection. The new milling process addresses all of these problems in addition to allowing us to address deeper cracks and pothole issues.