What is a Cape Seal and how is it compared to other Surface Treatments?

A Cape Seal is a chip seal covered with a slurry or micro-surface. The benefits from using a cape seal include a very smooth surface with an increased durability by sealing the subbase. Often the use of a chip seal is not popular with the public because of the rougher ride and loose stones. With the addition of the top treatment, a slurry seal or micro-surfacing, the road ends up with a smooth surface that binds any loose aggregate, reducing stone loss.

Image of Rumble Strip from FHWA Website
Cape seal demonstration at the 2012 Highway School

Cape Seals have been used to not only protect the pavement by sealing it, but it can also be used for heavy traffic areas and to address minor cracking. As with any surface treatment large cracks and potholes must be addressed prior to its application. Minor cracks, including low severity alligator cracks, can be addressed with the use of a polymer modified or an asphalt rubber modified chip seal

According to the National Park Service, cape seals can extend the life of a pavement 6 to 8 years; polymer modified Cape Seals may extend pavement life up to 10 years in ideal situations. The use of a Cape Seal is typically used on rural and urban highways and residential neighborhoods and should be considered when a slurry or micro-surfacing will not adequately address the distresses found on a roadway. The application of the initial chip seal represents approximately 50% - 60% of the costs of the application with the Slurry seal or micro-surfacing representing the remaining costs.

Resources

Asphalt Seal-Coat Treatments, USDA Forest Services, Technology and Development Program, 7700-Transportation Systems, April 1999.

National Center for Pavement Preservation

Preservation Treatment gallery

FHWA Preservation Brochures

VSS (Valley Slurry Seal Co.) website, December 2009

Liquid Asphalt Distributors Association of New York (LADA)

CLRP Tech Assistance logo

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.