Identifying Pavement Distresses Assists in Selecting the Correct Maintenance Options
Throughout the service life of a pavement, new distresses will continually be formed by traffic overloading and the natural enemies of asphalt (sun, air, temperature, and water). Therefore, all pavements require periodic maintenance to extend their useful life and maximize the investment. This guideline provides general information about why and how pavements deteriorate. Understanding the basics of pavement distresses is beneficial for creating a proper pavement maintenance plan, which can save money and protect your investment.
General cracking can occur as a single crack or as a series of cracks in seemingly random locations. These cracks can occur for a number of reasons, including: cold temperatures, settlement of the aggregate base or subgrade material, frost heave, or reflection of previously overlaid cracks. Cracked pavement allows water to flow through the asphalt to the aggregate base and subgrade deteriorating the asphalt and weakening the subgrade.
Maintenance Option: Crack sealing will prevent water from reaching the aggregate base.
Block cracking is the interconnection of several cracks that develop as the pavement ages. Block cracking is identified by the signature square-like pattern formed on the pavement from the cracks.
Maintenance Option: Crack sealing and/or sealcoating the pavement can help protect the pavement, but a mill and overlay is a good rehabilitation option before the pavement deteriorates further.
Fatigue cracking is a series of interconnected cracks typically described as resembling alligator skin. It is a structural distress, caused by overloading thin pavements or a weak aggregate base or subgrade. This distress can occur in small localized areas or can be widespread.
Maintenance Option: Full-depth patching is recommended in areas with localized fatigue
cracking, however, reconstruction is required if the fatigue cracking is a widespread problem.
Deformations and Depressions
Deformations and depressions are vertical movements of the asphalt pavement caused by overloading or settlement of a weak subgrade. These depressions provide areas for water to pool, which causes the pavement to deteriorate more quickly, leading to the development of potholes.
Maintenance Option: Mill patching can be used to repair these deformations and depressions in parking lots.
Raveling is the progressive loss of asphalt material from the pavement surface. This typically occurs slowly over a large area, or it can occur quickly in smaller areas forming potholes. Raveling can be identified when exposed rocks can be seen on the pavement surface.
Maintenance Option: Rejuvenating sealcoats, emulsion sealcoats, or chipseals can be applied to the pavement surface to protect it from further oxidation and raveling.
Potholes are the localized loss of pavement material typically caused by structural failures, poor drainage, or severe raveling. Potholes are a safety hazard and should be filled quickly.
Maintenance Option: Full-depth patching is recommended for all potholes, but fill-in patching can be used for a quick, temporary fix.