Crocodile cracking

Crocodile cracking is a type of crack that occurs on the surface of an asphalt paved road as a result of repetitive distress or flexing under stress. This type of cracking resembles the skin of a crocodile or alligator. As a result, it’s also interchangeably referred to as alligator cracking. There are different levels of severity depending on the extent of damage. The simplest or earliest stage of the cracking are longitudinal cracks which may or may not interconnected resembling a hairline fracture. The next stage is more severe where the surface cracks into a network of pieces which are interconnected known as spalling of the surface. This stage can be defined as an intermediate stage of severity. The final and more advanced stage resembles the skin and texture of a crocodile which means more pronounced cracks which are chunks of asphalt which can lead to hazards. By this stage, the fixing of the cracks at a surface level is often not possible and demands road closure to avoid accidents. Crocodile cracking is often localised and if the subgrade is severely impacted may have repetitive regions of breakdown. Crocodile cracking is a type of fatigue cracking that refers to a general type of cracking which is caused by iterative traffic loads, over a period of time. Repetitive surface stress on the asphalt pavement in sections where the tensile strain and stress are high under vehicular loads leads to deformation. This repetitive flexion or bend leads to interconnected cracks, which spread and propogate further at right angles as more time passes. There are three contributory factors that lead to crocodile cracking: namely freeze-thaw cycles, water intrusion into the subgrade, or lastly, subgrade compromise due to water softening from leakage leading to deformation. Crocodille cracking can also be bifurcated based on whether it’s under the path of a wheel, or wheel path, or non-wheeled path. If cracks appear along a wheel path, along the length of the road, or pavement, it’s largely attributed to fatigue under loads. However, if it’s not under a wheel path, yet parallel to the centre of the pavement, we can assume these type of cracks are due to the subgrade being impacted by moisture content, leading to cracks in the surface. These point more to the quality of the construction than surface level cracks caused by pressure.