Using infrared (IR) imaging and ground-penetrating radar (GPR) for uniformity measurements on new hot-mix asphalt (HMA) layers
Technologies to Enhance Quality Control on Asphalt Pavements (R06C)
The uniformity of HMA materials is critical to the durability and performance of an asphalt product. Segregation and inadequate and non-uniform density continues to be a major construction-related problem around the nation, with a significant adverse impact on pavement service life. Commonly used QC testing procedures only provide limited information on the overall uniformity of the HMA product. The ability to provide information that is real-time, non-destructive, and covers the full pavement width for both thermal uniformity and densification will greatly aid in improving the quality of HMA.
SHRP2 examined two nondestructive techniques for measuring uniformity and potential defect areas in asphalt pavements during construction. Both technologies (infrared and radar) offer real-time testing of potentially 100 percent of the pavement area, providing much more inspection coverage than existing QC methods. These new technologies improve the state of the practice for obtaining quality control data in hot- or warm-mix construction.
The infrared technology focuses on the thermal uniformity equipment, which enables inspectors and paving crews to measure the real-time mat temperature and make adjustments. The GPR technology provides greater area information on pavement densification of thin lifts after rolling, allowing for quicker turnaround and potentially avoiding costly and time-sensitive nuclear testing.
Products include recommendations for equipment and testing protocols for using infrared and GPR for testing the entire surface area during new HMA construction, and IR guide specifications.
Real-time temperature QC allows for prompt adjustments by the paving crew, thereby minimizing segregation problems that can occur when the temperature is too low. Using GPR technology reduces the reliance on single-point density gauges and instead provides greater pavement coverage. In addition to savings resulting from these innovations, near-term benefits include
- More uniformly constructed hot- and warm-mix asphalt layers
- Better in-place field density
- Improved communication among paving crews, their supervisors, and transportation agency personnel
- Improved ride
- Reduced discrepancies between contractor and agency test data
In the long term, implementation of these commercially available products could result in longer-lived pavements, enabling agencies to stretch their funding further and decrease user costs.
In the Field
|Alabama||Implementation Assistance Program – The Alabama Department of Transportation is using the IR technology to potentially improve the quality of the contractor's laydown operations for all types of paving projects from new construction to routine resurfacing projects. Development of specifications for the use of IR technologies through contract initiatives is also being explored.||Lead Adopter (infrared)||
Lyndi Davis Blackburn
|Alaska||Implementation Assistance Program – The Alaska Department of Transportation and Public Facilities is planning to use IR to gain 100 percent test coverage of highway projects so that failure areas are detected and corrected early. Success will be defined as asphalt pavements that function well for 20 years.||Lead Adopter (infrared)||
Richard S. Giessel
|Illinois||Implementation Assistance Program – The Illinois Department of Transportation (IDOT) is expanding its use of IR technology in an effort to attract and educate contractors on how to optimize their practices on IDOT’s new performance specifications, thereby maximizing their compensation. The IR equipment will also allow for the establishment of a meaningful way to verify the viability of using certain equipment on paving operations.||Lead Adopter (infrared)||
|Maine||Implementation Assistance Program – The Maine Department of Transportation is using GPR to perform density testing on very thin asphalt overlays. The increased coverage afforded by GPR will allow the evaluation of compact uniformity, as well as identify areas that need additional testing to determine acceptance.||Proof of Concept (ground penetrating radar)||
|Maine||Implementation Assistance Program– The Maine Department of Transportation has dealt with pavement issues resulting in the removal and replacement of large quantities of asphalt. The use of IR technology will provide a tool for contractors to improve the consistency of their practices as well as provide a level of unbiased measure of mat quality.||Lead Adopter (infrared)||
|Missouri||Implementation Assistance Program – The Missouri Department of Transportation is investigating the use of non-destructive methods of testing to evaluate asphalt for a more uniform product. The technology will be utilized with Superpave projects with the goal of familiarizing the agency and contractors with the technology and encourage routine use.||Lead Adopter (infrared)||
|Nebraska||Implementation Assistance Program – The Nebraska Department of Roads is using GPR technology to support their longitudinal density specifications and increased use of thin overlay strategies for pavement preservation.||Proof of Concept (ground penetrating radar)||
Robert C. Rea
|New Jersey||Implementation Assistance Program – The New Jersey Department of Transportation is using IR technology first on smaller projects to produce a better product that achieves a longer service life. Use of the technology is expected to reduce issues associated with the construction aspect of paving projects.||Lead Adopter (infrared)||
|North Carolina||Implementation Assistance Program – The North Carolina Department of Transportation will use IR technologies to gain valuable information on the temperatures during placement of asphalt mixtures to reduce degradation and raveling of the mat and future maintenance issues. The resulting information will allow for the location and repair of problem areas in the mat prior to placing traffic on the new surface.||Lead Adopter (infrared)||
|Virginia||Implementation Assistance Program – The Virginia Department of Transportation is considering these technologies as an integral part of a modified acceptance plan for asphalt as well as developing familiarity with more Virginia contractors.||Lead Adopter (infrared)||
|Virginia||Implementation Assistance Program – Federal Lands Highway will deploy IR technologies on a major Design-Build construction project for a portion of Route 1. Work will include milling and overlay work and substantial new construction with various asphalt pavement mix designs and thicknesses. Success will primarily be measured as a function of pavement density and the contractor achieving the density requirements.||Lead Adopter (infrared)||
|West Virginia||Implementation Assistance Program – The West Virginia Department of Transportation (WVDOT) is quantifying how activities upstream from the paver’s screed affect the thermal segregation of the mat. WVDOT will define success as production of pavements that have better performance than what is currently being experienced, along with the adoption of this technology by contractors.||Lead Adopter (infrared)||