A multitude of factors must be considered when considering the design of a Chip Seal system. With the understanding that all materials must meet project specifications, use the best local aggregates with the most compatible binders while considering climate, traffic type and count. Once the binder and aggregate are selected there are procedures to determine the rates of application for each.

Material compatibility, as well as aggregate and binder application rates are determined primarily by two commonly used mix design methods. The most common methods are the McLeod method and the Modified Kearby method.

The binder is applied by an asphalt distributor which has the capability of applying the design rate at the desired width. The binder application is followed by a mechanical aggregate spreader that is also capable of applying a design rate at the desired width. Then rolling is performed with pneumatic rollers to set the cover aggregate into the binder. There are also application machines that are capable of performing multiple processes in a single unit to include asphalt binder, aggregate, and even rolling of the aggregate. Finally, if there is any loose aggregate, it is removed by a rotary broom.

There are many Chip Seal combinations available to address the surface demands for any given project. Chip Seal is normally one application but can be applied in double or even triple applications if needed. Multiple applications commonly use different sizes of aggregates, typically decreasing in gradation size as each layer is applied, to help “lock” the applications together. Additionally, Chip Seal is commonly used as the first layer in the application of a Cape Seal project, utilizing either Slurry Seal or Micro Surfacing as the surface course.

Chip Seal is a cost-effective approach to restoring skid resistance and sealing the existing road surface from moisture damage and oxidation. It can be applied using local maintenance personnel with minimal equipment requirements. A finished Chip Seal is very pleasing in appearance and traffic markings show up very well.