9.3.4 Protective-coating selection considerations—A coating or insulation system can be applied to the installed FRP system to protect it from exposure to certain environmental conditions (Bisby et al. 2005a; Williams et al. 2006). The thickness and type of coating should be selected based on the requirements of the composite repair; resistance to environmental effects such as moisture, salt water, temperature extremes, fire, impact, and UV exposure; resistance to sitespecific effects; and resistance to vandalism. Coatings are relied on to retard the degradation of the mechanical properties Table 9.1—Environmental reduction factor for various FRP systems and exposure conditions of the FRP systems. The coatings should be periodically inspected and maintained to ensure the effectiveness of the coatings.
External coatings or thickened coats of resin over fibers can protect them from damage due to impact or abrasion. In high-impact or traffic areas, additional levels of protection may be necessary. Portland-cement plaster and polymer coatings are commonly used for protection where minor impact or abrasion is anticipated.