Pavement Maintenance - Cornell Local Roads Program - Cornell ...

7 - Patching
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Patching is the single most common pavement maintenance technique. As the repair area gets
larger, some agencies refer to it as a box-out or an area repair. The goals and concerns for an area
repair are the same as for patching. The difference is scale and economics.
Reasons for Patching
Patching fixes localized distress and may improve safety by reducing roughness. It is used to
repair structurally deteriorated pavement. Patching can also reduce the rate of deterioration of
nearby pavement and fix distressed areas prior to pavement overlays. There are three general
types of patching: semi-permanent, spray, and demand.
Semi-permanent patching is done in the summer to fix potholes, repair poor patches, and replace
demand patches placed earlier in the year. It is also performed with utility cuts and culvert
installations. These types of patches should have nearly the same strength as the surrounding
area. Drainage repairs are generally performed at the same time. The base is replaced if
necessary. If drainage and base repairs are not made, the original problem may reappear.
Spray patching is done with specialized equipment. It can either be planned or demand driven. A
spray patch vehicle can be used in almost any weather, but summer spray patching is generally
more successful.
Demand patching is an unplanned repair to fix potholes. It is performed in the winter or spring,
in all kinds of weather. It is usually done with patch material taken out by dump truck. The
choice of material greatly influences the success of the patch.
Semi-permanent Patching
Semi-permanent patching is essentially a small-scale hot-mix asphalt paving operation. Some of
the same concerns about patching (weather, materials and construction) also apply to semipermanent
patching. For more details on asphalt paving, see the Cornell Local Roads Program
manual entitled Asphalt Paving Principles (see Appendix B).
A recent Pennsylvania study found semi-permanent patching to be three times more cost
effective than other patching techniques, when full life cycle costs were considered. The initial
capital cost is high, but the overall success rate may justify it. The study found that the lesspermanent
patches usually had to be repeated multiple times, which made them more costly in
the long run.
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