Why Crack Type Matters
Treating the wrong crack the wrong way wastes money. More importantly, sealing over a base-failure crack does not fix it — it hides the problem while water continues to destroy the structure underneath.
The 6 Main Crack Types
1. Hairline Cracks
What they look like: Very thin, surface-only cracks in a generally uniform pattern. Often appear in older asphalt.
Cause: Surface oxidation and drying out of the asphalt binder over time.
What to do: Sealcoating fills hairline cracks effectively.
2. Longitudinal Cracks
What they look like: Long cracks running parallel to the direction of paving.
Cause: Poor joint construction during paving, edge settlement, or thermal expansion and contraction.
What to do: Hot-pour crack fill. If the crack is wide (over half an inch), saw-cut and rout before filling for better adhesion.
3. Transverse Cracks
What they look like: Cracks running perpendicular to the pavement direction.
Cause: Temperature cycling — asphalt contracts in cold weather and the weakest points crack first.
What to do: Hot-pour crack fill.
4. Edge Cracks
What they look like: Cracks near the edge of the pavement, sometimes with crumbling.
Cause: Lack of lateral support at the pavement edge, water infiltration from the side, or vehicles driving on the edge.
What to do: Fill the cracks, address drainage, and consider edge repair if crumbling is significant.
5. Alligator Cracking
What they look like: Interconnected cracks forming a pattern resembling alligator skin or chicken wire.
Cause: This is a base failure indicator. The structural section has lost its load-bearing capacity — usually from water infiltration compromising the sub-base.
What to do: Crack filling and sealcoating will not fix this. The failed section needs to be removed and rebuilt from the base up.
6. Pothole Formation
What they look like: Bowls or holes in the surface.
Cause: Advanced alligator cracking that has progressed to surface failure under traffic.
What to do: Infrared repair or cut-and-patch.
Quick Reference
| Crack Type | Severity | Fix |
|---|---|---|
| Hairline | Low | Sealcoating |
| Longitudinal | Low-Medium | Hot-pour crack fill |
| Transverse | Low-Medium | Hot-pour crack fill |
| Edge | Medium | Fill plus drainage work |
| Alligator | High | Base repair required |
| Pothole | High | Cut-and-patch or infrared |
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