Minnesota Department of Transportation

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NCAT Partnership

HMA Performance Test

Orange barrels on a highway

HMA Performance Test

The Minnesota Road Research Project (MnROAD) and National Center for Asphalt Technology (NCAT) formed a partnership for the first time to execute asphalt mixture performance testing experiments with a nationwide implementation impact.

The MnROAD Cracking Group (CG) experiment will focus on low-temperature cracking. However, depending on the type of sections constructed at MnROAD there will be a potential for other types of cracking such as fatigue and top-down. Construction of the experimental sections will take place summer 2016.

Objectives

The objective of the CG experiment is to validate laboratory cracking tests by establishing correlations between the test results and measured cracking performance in real pavements (test sections) within a very short timeframe.

Agencies

The CG experiment is a 3-year pooled-fund project sponsored by five states including Illinois, Michigan, Minnesota, New York, and Wisconsin.

Scope

This experiment will construct and traffic a series of new test sections at MnROAD with differing asphalt mixtures that have a range of expected cracking susceptibilities. Research efforts and construction will control other factors that affect cracking, such as layer thickness and underlying layer stiffness to the highest degree possible. A suite of laboratory cracking tests conducted on the mixes will identify which test results best correlate with field cracking. Reviews of recent research suggest the following tests for low-temperature and reflective cracking sections in the cracking study, with the actual methods determined by consensus among agencies that participate:

  • Disk-Shaped Compact tension (DCT) test for low and intermediate temperatures;
  • Semi-Circular Bend test (SCB), MN, IL, and LTRC variations; and
  • Indirect Tensile strength test;
  • Bending beam fatigue; and
  • Overlay tests (TX and NCAT).

Analysis of laboratory cracking tests will also consider their variability, utility and practicality of implementation for both mix design approval and quality control testing. A crucial component of the study is regular performance monitoring of the pavement test sections for ride quality, distresses, strength, and response.

Current Status

The project is currently in the design phase. Anticipated timeframe for key activities is summarized below:

Project schedule to be announced

Construction Updates