Durability of advanced composites in a marine environment

The high cost of infrastructure repair due to corrosion of steel has led to a worldwide interest in the feasibility of using alternative fiber reinforced polymer (FRP) material. FRPs have long been used by the aerospace industry where it enjoys an excellent reputation for corrosion resistance. Whether such a reputation is justified for civil engineering applications remains to be fully established. Over the past decade, the University of South Florida has conducted a number of long-term studies to assess the likely performance of FRP material used for prestressing piles driven in a marine environment. In the investigations, aramid, carbon and fiberglass – all identified as suitable for prestressing applications – were tested. The studies attempted to obtain answers to the following questions: Are FRP materials durable in concrete? Do they become more brittle with age and exposure? Does the bond between concrete and FRP deteriorate with exposure? Does the polymer matrix deteriorate in concrete? Most importantly, how do these changes collectively impact the strength and serviceability of FRP pretensioned elements? This paper describes the basis, scope and methodology adopted in the investigations and summarises some of the principal findings.