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Surface defects are related to problems in the surface layer. The most common types of surface distress are: 1. Raveling 2. Bleeding 3. Polishing 4. Delimitation Ø Raveling: Raveling is the loss of material from the pavement surface. It is a result of insufficient adhesion between the asphalt cement and the aggregate. Initially, fine aggregate breaks loose and leave small, rough patches in the surface of the pavement. As the disintegration continues,   larger   aggregate   breaks   loose,   leaving   rougher   surfaces.   Raveling   can   be accelerated by traffic and freezing weather. Some raveling in chip seals is due to improper construction technique. This can also lead to bleeding. Repair the problem with a wearing course or an overlay. Ø Bleeding: Bleeding is defined as the presence of excess asphalt on the road surface which creates patches ...

The progressive   breaking   up   of the   pavement   into   small, loose   pieces   is   called disintegration. If the is integration is not repaired in its early stages, complete reconstruction of the pavement may be needed. The two most common types of disintegration are: 1. Potholes 2. Patches Potholes: Potholes are bowl-shaped holes similar to depressions. They are a progressive failure. First, small fragments of the top layer are dislodged. Over time, the distress will progress downward into the lower layers of the pavement. Potholes are often located in areas of poor drainage, as seen in Figure. Potholes are formed when the pavement disintegrates under traffic loading, due to inadequate strength in one or more layers of the pavement, usually accompanied by the presence of water. Most potholes would not occur if the root cause was repaired before development of the pothole. Repair by excavating an...

Pavement deformation is the result of weakness in one or more layers of the pavement that has experienced movement after construction. The deformation may be accompanied by cracking. Surface distortions can be a traffic hazard. The basic types of surface deformation are: 1. Rutting 2. Corrugations 3. Shoving 4. Depressions 5. Swell Ø Rutting Rutting is the displacement of pavement material that creates channels in the wheel path. Very severe rutting will actually hold water in the rut. Rutting is usually a failure in one or more layers in the pavement. The width of the rut is a sign of which layer has failed. A very narrow rut is usually a surface failure, while a wide one is indicative of a sub grade failure. Inadequate compaction can lead to rutting. Figure shows an example of rutting due to sub grade Failure. Minor surface rutting can be filled with micro paving or paver-placed surface treatments. Deeper ruts ma...

Ø Fatigue cracking (Alligator cracking): Fatigue cracking is commonly called alligator cracking. This is a series of interconnected cracks creating small, irregular shaped pieces of pavement. It is caused by failure of the surface layer or base due to repeated traffic loading (fatigue). Eventually the cracks lead to disintegration of the surface, as shown in Figure. The final result is potholes. Alligator cracking is usually associated with base or drainage problems. Small areas may be fixed with a patch or area repair. Larger areas require reclamation or reconstruction. Drainage must be carefully examined in all cases. Longitudinal cracking: Longitudinal cracks are long cracks that run parallel to the center line of the roadway. These may be caused by frost heaving or joint failures or they may be load induced. Understanding the cause is critical to selecting the proper repair. Multiple parallel cracks may eventually form from the initial crack. This pheno...