Chip seals are designed to protect pavement. They are used to increase skid resistance and macrotexture of the road surface. Chip Seals are one of the oldest and most cost-effective methods of pavement restoration. In many countries it is used for high volume roads. Here in the U.S. we primarily use it for pavement preservation and rehabilitation.
A chip seal involves the application of a binder in the form of an emulsion or hot spray. Sometimes this binder can also be a cutback with an aggregate as close to single size as possible. Several factors are critical to proper Chip Seal usage including: oil application rate, stone cleanliness & embedment, aggregate shape & grade, the amount of binder and weather conditions during application.
The existing pavement must be structurally sound because chip seal is not designed to significantly increase structural capacity. Moderate to severe cracks or any other distresses should be sealed or repaired first. The surface should also be cleaned prior to treatment. A treatment with chip seal is ideal for pavements with loss of surface texture. It is also useful in preventive maintenance on aging pavements that are still in good condition with minimal surface distress.
Chip sealing is a three stage process:
1) After the surface has been prepared by patching and crack filling (if required), a spray of binder is applied.
2) Next a layer of aggregate is applied using a chip spreader.
3) The final operation is several passes from a multi wheeled pneumatic roller.
The road is usually opened to traffic after sweeping or may be opened to slow moving traffic almost immediately. The result is a road that is better to drive on, while protecting and extending pavement life. Chip Sealing is a thin layer of coating. It is more economical and will provide better value than hot mix overlays for the same purpose.