U.S. SEALCOAT
Alligatoring -Repairs.cfm

Alligatoring (a.k.a. Spider Cracks)


Cracks that form very closely together and in high prevalence are more serious than the cracks repairable with sealant and fill. These cracks are usually caused by inadequate strength or compaction of base and/or subgrade. Also, poor drainage can lead to early development of Alligatoring pavement.

Stage One.
These cracks begin with branched, discontinuous thin cracks that interconnect slightly to form a typical alligator pattern. In many cases, the initial Alligatoring forms around a single, center crack with many intermittent smaller cracks running at angle from it. The cracks are usually no more than ¼" wide.

Stage Two.
The cracks become more prevalent and wider, sometimes wider than ¼". The cracking has become completely interconnected but the pavement pieces, which are usually less than 12" at the longest dimension, stay mostly in place. These pieces are tightly held together and individual pieces rarely become displaced.

Stage Three.
The cracks are most prevalent and wide, as well as being highly interconnected. Although the pieces are still small - usually less than 12" at the longest dimension - they are very loose and can easily become displaced with traffic. As progressively larger and deeper pieces become displaced, potholes develop in the pavement surface that can reach as deep as the subgrade (depending on base condition).

Remedy
As the Alligatoring inherently means many interconnected cracks in the pavement as well as the underlying base, subgrade and/or drainage problems, Cutting and Patching is the most effective repair remedy. This involves:
  1. Cutting the area square beyond the damaged area - to ensure underlying problems that have not yet surfaced are also corrected - with a jack hammer.
  2. The broken asphalt is then excavated and the base is compact as necessary to prepare for new asphalt.
  3. At least 1.5" of asphalt binder and 1.5" of asphalt topcoat are installed and compacted.
  4. Edges are emulsified and sanded for proper bonding.
NOTE: Jack hammering is predominantly used because of the toothed effect on the pavement, where the newly installed asphalt fits with old asphalt in the most effective way. Saw cutting is also available upon request.