SUMMARY REPORT ON LOW TEMPERATURE AND THERMAL FATIGUE CRACKING

Under a long term research program to develop test methods which are suitable to accurately and reliably characterize the engineering properties of asphalt-aggregate mixtures, an exhaustive literature review and an analysis of responses to a survey questionnaire was conducted to identify test methods that are currently used to predict low temperature and thermal fatigue cracking in asphalt concrete pavements. Eight test systems/methods were identified. These methods were evaluated in terms of the following criteria: 1) Simulation of field conditions; 2) Application of test results to mechanistic models; 3) Suitability for aging and moisture conditioning; 4) Potential to accommodate large stone mixes; 5) Ease of conduct; 6) Cost of equipment. Based on the evaluation of the test systems/methods presented, it would appear that four test systems/methods warrant further consideration in a laboratory test program, as follows: 1) Direct Tension-Constant Rate of Extension test; 2) Thermal Stress Restrained Specimen test; 3) C*-Line Integral test; 4) Coefficient of Thermal Expansion and Contraction test. A test program is identified which should be conducted to provide a preliminary evaluation of the availability of selected test systems/methods (1) for standardization, and (2) to provide input parameters to mechanistic models for low temperature and thermal fatigue cracking.