Implementation of Laboratory Testing to Predict Low Temperature Cracking Performance of Asphalt Pavements

In cold climate regions, thermal cracking of asphalt pavements is a major pavement distress. Cold climates cause a thermal contraction within the pavement. When combined with the brittle behaviour of asphalt at low temperatures, the thermally induced stresses are relieved by transverse cracks forming in the pavement. This cracking facilitates poor ride quality and premature failure of the pavement. There is currently no asphalt mixture performance test required by majority of Department of Transportations (DOTs) in the United States to address the issue of thermal cracking. Previous research has indicated that fracture energy of asphalt mixtures is a reliable predictor of transverse cracking performance. This mechanistic property of asphalt mixtures can be found using the disk-shaped compact tension (DCT) test. On basis of previous research, a low-temperature cracking performance specification that uses DCT fracture energy has been developed. During 2013 construction season, five construction projects were chosen to implement provisional specifications that use fracture energy as a required mix parameter. The projects encompassed different construction techniques, material compositions and climatic zones. The implementation procedure as well as the results from testing is presented in this paper. The results indicate a shift in the DCT fracture energy values between laboratory produced specimens that were provided as part of mix design acceptance and those manufactured using plant produced mix. Other findings include reaffirmation of common knowledge that use of higher binder contents and/or improved low temperature binder grades provide mixtures with improved fracture energies.