A cape seal is a process that includes placing a chip seal on the existing surface and then after a few days placing a slurry seal or micro surfacing layer on top of the chip seal.
To place the chip seal, an asphalt distributor provides application of the binder to the pavement surface. A chip spreader immediately applies a uniform, predetermined rate of aggregate onto the binder. These two operations are at the heart of constructing a surface that is one stone thick and has enough asphalt to retain the aggregate, but not an excess amount of binder that causes the surface to bleed. Depending on the binder, aggregate, and actual type of chip seal being constructed, various rollers will be used to orient the aggregate to achieve appropriate embedment. Pneumatic rollers are typically found on all chip seal projects. The rollers are followed by the brooms that remove excess aggregate from the finished surface.
Slurry seal consists of a carefully designed mixture of asphalt emulsion (which may be polymer-modified), mineral aggregate, water and additives; proportioned, mixed and uniformly spread over a properly prepared surface at a single stone thickness. Slurry seal is applied as a homogenous mat which adheres firmly to the prepared surface and has a skid-resistant texture throughout its service life. Slurry seal is a quick-traffic system that allows traffic to return shortly (from one to four hours) after placement.
Micro surfacing consists of a carefully designed mixture of polymer-modified asphalt, mineral aggregate, water and additives, proportioned, mixed and uniformly spread over a properly prepared surface which is typically greater than one stone thick. Micro surfacing is applied as a homogenous mat which adheres firmly to the prepared surface and has a skid-resistant texture throughout its service life. Micro surfacing is a quick-traffic system that allows traffic to return shortly (typically less than one hour) after placement.
Equipment variations can include the following:
Material variations for chip seals can come from either different types or sized aggregates and from the different binders utilized in the chip seal process.
The most prevalent variation of slurry seal/micro surfacing is aggregate size:
Design variations make it possible to address additional pavement distresses such as rutting; as well as to address different traffic conditions from residential streets to Interstate highways. Notify the laboratory performing the mix design so they can create the optimal Job Mix Formula for the project.
SCRUB CAPE SEAL (SCRUB SEAL + MICRO SURFACING): Utilizing a scrub seal broom behind the asphalt distributor during the chip seal phase of a cape seal project helps to force more of the chip seal emulsion into the existing cracks further delaying reflective cracking.
Note: Some agencies also opt for a Cape Seal in lieu of a stand-alone Chip Seal in more heavily populated areas to provide a smoother texture finish wearing surface than the Chip Seal alone can provide.