Analysis of Thermal Fatigue Distress of Asphalt Concrete Pavements

Thermal cracking of asphalt concrete pavements is responsible for millions of dollars in annual maintenance and rehabilitation costs in the United States and Canada. Thermal cracking typically is associated with low temperatures in northern climates and at high elevations. Another form of thermal cracking, known as thermal fatigue cracking, has been proposed by several researchers as a potential mode of distress in regions with relatively moderate climates. The objectives were to evaluate the possibility of the occurrence of the thermal fatigue cracking mode of distress and to identify a suitable laboratory test procedure to facilitate a mechanistic analysis of this mode of distress. The most promising test procedures evaluated included the direct tensile creep test and the thermal stress restrained specimen test. The results suggest that thermal fatigue distress in asphalt concrete mixtures is not a viable mode of distress in the absence of environmental aging. From the data presented and results documented by others, it is evident that distress often attributed to thermal fatigue cracking is more likely the result of low-temperature cracking of environmentally aged mixtures or subgrade-related distress. It is concluded that fatigue distress due to thermal loading of semirestrained pavements does not occur.