Alligator Cracking in Flexible & Rigid Pavement : With Causes & Repair

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Alligator cracking is the type of cracking that is associated with load and structural distresses.

These cracks are extensively found at intersections where the vehicles are stopped for a relatively long period because these cracks start to form when the sub-grade and base compress due to the excessive imposed wheel load.



  i. Alligator Cracking in Flexible Pavement  


Causes of Alligator Cracking in Flexible Pavement

1. Weakness in base, surface or sub-grade

2. Thinning of a surface course or base course

3. Poor Drainage

4. Excessive vehicular loads

5. Vehicle stopped for a relatively long period


Repair of Alligator Cracking in Flexible Pavement

a. Determine the main source of the problem and the best way for repairing it.

b. If a problem is seen on the surface course then application of crack filler is done.

b. If failure is due to weakening of base or sub-base course; then cut the affected pavement area into rectangular or square shapes. Then patch it like a pothole.



  ii. Alligator Cracking in Rigid Pavement  


Causes of Alligator Cracking in Rigid Pavement

a. Weakening of base

b. Poor drainage

c. Poor quality material mix or use.


Repair of Alligator Cracking in Rigid Pavement

1. Full Depth Patching:

It is a widely used method for treating alligator cracks in rigid pavements and restoring the structural stability and rideability of the pavements.

It includes the following series of steps:

a. Defining repair boundaries:

The boundary of the area to be repaired must be first defined by surveying the region.

b. Sawing old concrete:

Using full-depth saw cuts, the damaged area is first isolated from the remaining area. Full-depth saw cuts facilitate the separation of damaged concrete from the adjacent concrete with minimal damage.

c. Removing old concrete:

The removal of concrete can be carried out either by lift out or by the breakup. Lifting sawed concrete is faster, requires less labor, and also doesn’t cause any significant damage to the adjacent layers.

In some cases, lifting concrete can be risky and in such a situation the deteriorated concrete is broken into smaller fragments and removed by backhoe or hand tools.

d. Preparing the patch area:

After the removal of old concrete, the area to be patched is prepared. If the area contains water, it must be pumped out and cleaned properly.

e. Placing and Finishing new concrete:

Placing of the new concrete is usually done by ready-mix trucks or other mobile batch vehicles. Concrete must be evenly distributed and spread. Using the finishing tools, the placed concrete is finished.


Read Also: 6 Types of Pavement Failure


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