Water bleeding (left two photos) occurs when water seeps out of joints or cracks or through an excessively porous HMA layer. Pumping (right-most photo) occurs when water and fine material is ejected from underlying layers through cracks in the HMA layer or out the sides of the HMA layer under moving loads.
Water bleeding through a pavement surface on a rural mountain highway. The subgrade around the pavement is still wet from a recent rain indicating that the water has come up through a porous pavement.
Decreased skid resistance, an indication of high pavement porosity (water bleeding), decreased structural support (pumping)
- Porous pavement as a result of inadequate compaction during construction or poor mix design
- High water table
- Poor drainage
Water bleeding or pumping should be investigated to determine the root cause. If the problem is a high water table or poor drainage, subgrade drainage should be improved. If the problem is a porous mix (in the case of water bleeding) a fog seal or slurry seal may be applied to limit water infiltration.