7 Types of Asphalt Cracking and their Causes
Asphalt cracking can be caused by a variety of factors including weather, drainage, materials, and traffic. Correct identification and timely maintenance are crucial in preventing further deterioration.
Below is a comprehensive view of the 7 types of asphalt cracking and a discussion about why these cracks occur.
1. Edge cracking
Edge cracks are longitudinal cracks located near the edges of the pavement and can be caused by factors such as settling of underlying material, soil drying, and lack of lateral support. Clearing nearby trees and shrubs and improving drainage can help prevent these cracks from occurring or worsening.
2. Slippage cracking
Slippage cracks appear crescent-shaped and can be caused by factors such as non-adhesive materials between layers, poor bonding between the surface and underlying material, and low-strength or deficient asphalt mix. These factors can lead to the development of slippage cracks in asphalt pavements.
3. Reflection cracking
Reflection cracks occur when an overlay of asphalt pavement is placed over an existing cracked or jointed pavement structure. The movement or shifting of the underlying pavement can then cause the cracks or joints to reflect to the surface, resulting in reflection cracks.
4. Transverse cracking
Transverse cracks run approximately perpendicular to the centerline of the pavement and can be caused by low temperature thermal cracking or a hard asphalt grade that is not suitable for the climate. These cracks are often due to asphalt shrinkage and are not directly related to traffic loads, but heavy traffic can worsen the condition.
5. Fatigue/Alligator cracking
Fatigue cracks, also known as crocodile or alligator cracking, get their name from their resemblance to the skin of alligators. These cracks are load-related and can be caused by a weak base, subgrade, or surface, as well as poor drainage.
6. Block cracking
Block cracking appear as large rectangles or squares on the pavement surface. Block cracks in pavement can occur due to lack of moisture or extreme temperature cycles which cause the asphalt binder to contract or expand insufficiently. Traffic load is usually not a factor in this case.
7. Longitudinal cracking
Longitudinal cracks in pavement run parallel to the centerline and can be caused by factors such as shrinkage of the asphalt, poor joint construction, or improper paver operation.
We recommend that pavement testing is to be conducted prior to carrying out repairs. Cracking can be detected by the ARAN (laser and visual testing) or ROVER (visual testing only). To learn more about these specialised equipment, please visit https://www.pavement.com.au/automated-crack-detection-system