scope:

This guide is intended to aid in the proper selection and use of PC overlays for structures in the transportation industry, focusing primarily on bridge and parking garage decks. Materials discussed are epoxies, polyesters, methacrylates, and polyurethanes, for application on either concrete or steel surfaces.

In general, these overlays are used for the protection of the underlying substrate and are designed to be flexible, waterproof, etc. Although similar polymeric materials are used in PCs for patching and repairs, overlays are formulated with greater resiliency and stress-relieving characteristics. Such characteristics are necessary to withstand breakdown from repeated freeze-thaw cycles.

These are, therefore, a distinctly different class of materials and should be treated as such.

In addition to describing the characteristics of PC overlays, this guide includes chapters on surface preparation, application, evaluation, maintenance, and safety. The information should allow the reader to select materials for a given application, and may serve as the basis for the preparation of overlay specifications.