(4) Surface defects :

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  of  asphalt  cement.  Excessive  asphalt  cement  reduces  the  skid-resistance  of  a
pavement, and it can become very slippery when wet, creating a safety hazard. This is caused
by an excessively high asphalt cement content in the mix, using an asphalt cement with too
low a viscosity (too flow able), too heavy a prime or tack coat, or an improperly applied seal
coat. Bleeding occurs more often in hot weather when the asphalt cement is less viscous
(more flow able) and the traffic forces the asphalt to the surface. Figure 13 shows an example
of bleeding during hot weather.

Ø Polishing:

Polishing is the wearing of aggregate on the pavement surface due to traffic. It can
result in a dangerous low friction surface. A thin wearing course will repair the surface.