What defines "fatigue cracking" in asphalt pavements?

Fatigue cracking in asphalt pavements is primarily defined as cracking that occurs as a result of repeated loading cycles, which places stress on the pavement surface. Over time, this repeated stress leads to the development of cracks, often starting at the surface and propagating downwards. The phenomenon is closely associated with the material's ability to withstand deformation under repeated traffic loads—essentially, it reflects the weakening of the pavement structure due to fatigue over time.

The understanding of fatigue cracking is essential for pavement management and maintenance, as it indicates the area is experiencing distress primarily due to the continued passage of vehicles. Engineers need to monitor these types of cracks to anticipate necessary repairs and maintain the structural integrity of the pavement.

Other types of cracking mentioned, such as those caused by temperature changes, heavy traffic loads, or aging of asphalt binder, address different mechanisms of failure, but they do not encapsulate the specific scenario of fatigue cracking, which is uniquely tied to the effects of repetitive stresses on the pavement structure.