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Alligator Cracking in Asphalt Pavement: Causes and Control

Alligator Cracking in Flexible Pavement

Alligator Cracking in Flexible Pavement

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Alligator cracking is an interlaced cracking pattern observed on the asphalt pavement surface due to repeated traffic loading. Alligator cracks cause deterioration of asphalt pavement and resemble the scales on an alligator’s back.

Figure-1: Alligator Cracking in Flexible Pavement

This article explains the leading causes and the ways to prevent alligator cracking on asphalt pavements.

Causes of Alligator Cracking

When the asphalt pavement is subjected to repeated traffic loads, longitudinal cracks are formed along the wheel paths. After repeated loading, these longitudinal cracks connect to form multi-shaped sharp-angled pieces with a pattern similar to the alligator skin. This distress is caused due to:

  1. Loss of load-carrying capacity of the pavement’s base, sub-base, or subgrade support due to improper drainage or spring thaw issues.
  2. Increase in load on pavement greater than anticipated design load.
  3. Improper structural design of the pavement, i.e., pavement designed is too thin to take the design loads.
  4. Poor construction of pavement, i.e., inadequate compaction and subgrade preparation
  5. Improper drainage design for pavement
Figure-2: Drainage Provided for Asphalt Pavement

How to Control Alligator Cracking in Asphalt Pavement?

The main reason behind the occurrence of alligator cracking is excessive loads. However, some measures can help reduce the load on asphalt pavement and hence the chances of occurrence of alligator cracking. These include:

  1. Restricting the movement of heavy load vehicles like trucks or semis on the pavement.
  2. Designing the concrete pavement as per the expected loads. For example, the preparation needed for an asphalt pavement surface to support passenger cars is different from what is required for holding heavy loads like cargo trailers.
  3. Improving the drainage of the pavement so that water can flow out of the sub-base.
  4. Employing an asphalt repair specialist for redesigning the sub-base to increase the support for the pavement. Strengthening the asphalt base is a long-term repair and control option for alligator cracking issues in the pavement.
  5. If minor cracks are observed, they can be sealed to limit their propagation. A crack filler or seal must be used to fill the cracks.

FAQs

How are alligator cracks formed on asphalt pavement?


When the asphalt pavement is subjected to repeated traffic loads, longitudinal cracks are formed along the wheel paths. After repeated loading, these longitudinal cracks connect to form many-shaped sharp-angled pieces, with a pattern similar to alligator skin.

What are the main causes of alligator cracks on asphalt pavement?

The main causes of alligator cracks on asphalt pavement are excessive traffic loads and improper drainage of the pavement structure.

How to control alligator cracking in pavements?

An asphalt repair specialist must be employed to redesign the sub-base to increase the support for the pavement. Strengthening the asphalt base is a long-term repair and control option for alligator cracking issues in the pavement.

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