15 March 2001
8.3. Patching PFS. If correctly performed, a PFS patch should be virtually indistinguishable
from the remainder of the surface. The following steps shall be conducted for patching PFS.
8.3.1. Remove defective PFS. Sawing shall not be performed to patch a PFS. It is
recommended that a milling machine be used to remove any defective PFS. The full depth and
extent of PFS damage shall be milled.
8.3.2. Clean and tack repair area. Remove the defective material and, if necessary, repair the
underlying pavement. The repair area should be thoroughly cleaned before placing the tack coat.
A light tack coat should be applied to the bottom but not the edges.
8.3.3. Place patch material. The repair material should conform as closely as possible to the
existing PFS. After material placement, it should be rolled by using the same method as the
original construction. A cold-mix asphalt can be used for a temporary repair.
8.4. Raveling Control.
A procedure that will help control raveling
of the porous friction surface,
until replacement, is a very light spray application of asphalt emulsion. If this procedure is
performed, care should be taken not to hinder drainage of the PFS.
8.5. Patching Using Standard Hot-Asphalt Plant Mix. If a standard hot-asphalt plant mix is
used to repair a PFS, the following steps shall be taken.
8.5.1. Mark the repair area. The boundaries of the repair shall be determined and marked for
saw cutting. The patch must be diamond shaped with a point of the diamond at the high
elevation (Figure 8.2.). This will allow water to flow around the patch area.
8.5.2. Remove defective PFS. The area should be sawed to the thickness of the porous friction
surface. Defective material should be removed and care taken not to destroy the edges of the