A Simple Test Procedure for Evaluating Low Temperature Crack Resistance of Asphalt Concrete

The current means of evaluating the low temperature cracking resistance of hot mix asphalt (HMA) relies on extensive test methods that require assumptions about material behaviors and the use of complicated loading equipment. The purpose of this study was to develop and validate a simple test method to directly measure the cracking resistance of HMA under field-like conditions. A ring shape asphalt concrete cracking device (ACCD) was developed. The ACCD utilizes the low thermal expansion coefficient of Invar steel to induce tensile stresses in a HMA sample as temperature is lowered. The results of the tests of the notched ring shaped specimens compacted around an ACCD Invar ring showed good repeatability with less than 1.0°C (1.8°F) standard deviation in cracking temperature. A laboratory validation indicated that ACCD results of five mixes correlate well with thermal stress restrained specimen test (TSRST) results with the coefficient of determination , r² = 0.86. To prepare a sample and complete TSRST measurement, it takes minimum 2-3 days. For ACCD, two samples can be easily prepared and tested in a single day with a small test set-up. The capacity of ACCD can be increased easily with minimal cost to accommodate a larger number of samples. Among factors affecting the low temperature performance of HMA, the coefficient of thermal expansion (CTE) of aggregate has been overlooked for years. A composite model of HMA is proposed to describe the low temperature cracking phenomenon. Due to the orthotropic and composite nature of asphalt pavement contraction during cooling, the effects of aggregate CTE is amplified up to 18 times for a typical HMA. Of 14 Ohio aggregates studied, the maximum and the minimum CTEs are 11.4 and 4.0 x 10 to the -6 power/°C, respectively. During cooling, the contraction of Ohio aggregate with high CTE can double the thermal strain of asphalt binders in the asphalt mix and may cause asphalt pavement thermal cracking at warmer temperature.

  • Record URL:
  • Corporate Authors:

    Ohio University, Athens

    Ohio Research Institute for Transportation and the Environment
    141 Stocker Engineering and Technology Center
    Athens, OH  United States  45701-2979

    Ohio Department of Transportation

    Office of Research and Development, 1980 West Broad Street
    Columbus, OH  United States  43223

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Kim, Sang-Soo
    • Sargand, Shad M
    • Wargo, Andrew
  • Publication Date: 2009-11

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 122p

Subject/Index Terms

Filing Info

  • Accession Number: 01150233
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/OH-2009/5
  • Contract Numbers: 134260
  • Files: TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Feb 2 2010 11:16AM