ABSTRACT
The function of subsurface drainage is to control and/or drain subsurface water or moisture away from the pavement system especially the subgrade and subbase. Water may come through the joints or cracks of the pavement surface courses and from a high water table. Stripping can be described as a loss of bond between the asphalt binder and the aggregate surface. Once the asphalt binder film peels off the aggregate surface, the asphalt mix loses cohesion and starts to disintegrate usually causing potholes. Stripping in a four-lane highway facility occurs first in the slow traffic lane because it carries more and heavier traffic compared to the passing lane. A section of the East-West Pennsylvania Turnpike between Philadelphia and Pittsburgh was rehabilitated in 1977. This section received 100 mm asphalt overlay on the mainline and its 3 m wide median was also paved for the first time with a 75 mm asphalt binder and wearing course.
