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What is Alligatoring?


By Michael Coletta, PCM Asphalt Division Manager | August 28, 2013

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What’s the story behind those ugly cracks in your parking lot? Does the asphalt have areas where the pavement is rutted or severely broken? Does it sort of look like the back of an alligator? If so, your parking lot suffers from “alligatoring.”

Alligatoring is a condition easily recognized by a series of cracks grouped together in one area. This type of cracking is indicative of subgrade problems. The closer these cracks are together, the shallower the failure. Inversely, the further these cracks are apart, the deeper the failure.

How did this happen?

From day 1, asphalt begins to break down from the sun, rain, and load (traffic). The primary cause of failure is the permeation of water into the asphalt base. When water enters the base of the pavement, the base material is displaced and settles leading to further cracking and a depression in the surface. As water gathers in the depressed area, the asphalt deteriorates and becomes unstable. At this point, removal and replacement of the old asphalt is often the only solution. Over time all asphalt degrades naturally due to oxidation (and the breakdown of the surface. As water penetrates the asphalt it begins to speed up the failure process. Many times if the original asphalt is not constructed to meet the load placed on it (heavy trucks, etc.) it may fail quicker as well.

Want to learn more about the fundamentals of asphalt and asphalt repair? Download our Asphalt Paving 101 presentation.