Define "fatigue cracking" in asphalt pavements.

Fatigue cracking in asphalt pavements is defined as the cracking that occurs due to repeated loading over time, primarily from the weight of traffic. As vehicles travel over the surface, the asphalt undergoes stress and strain with each pass. This repetitive action weakens the pavement material, leading to the development of cracks. Over time, the cumulative effect of these loads causes the asphalt to become fatigued and crack, similar to how metal might fatigue after being bent repeatedly.

This type of cracking is typically seen in areas of the pavement that experience heavy traffic loads and can manifest as a series of interconnected cracks resembling a map, often referred to as "alligator cracking." Understanding this process is crucial for pavement management, as it can have significant implications for maintenance and repair strategies.

Other causes of cracking, such as moisture infiltration or thermal expansion, are related to different phenomena affecting asphalt but do not specifically address the failure mechanism associated with repeated mechanical stress.