Durability of fibre reinforced polymers used in concrete structures

Use of Fibre Reinforced Polymers in new and existing structures is increasing at a rapid pace. The effectiveness of structural upgrade in the short-term tests has been demonstrated repeatedly in the laboratory tests and field applications. However, the long-term durability of the FRP and FRP-reinforced concrete has not been investigated to a point that a designer can suggest the application of FRP with the same confidence as the traditional materials. In this paper, selected results from an extensive test program are presented in which the durability of FRP materials and FRP-reinforced concrete was investigated. The environmental parameters to which the specimens were subjected included freeze-thaw cycling (50, 100, 200, and 300 cycles), UV radiation (1200, 2400, and 4800 hours), temperature variation (28, 56, 112, and 336 cycles), NaOH solutions with pH 10 and pH 12 concentrations (7, 14, 28, and 84 days), and moisture (7, 14, 28, and 84 days). Specimens comprised FRP coupons and FRP-FRP single lap bond specimens. The tests carried out on the specimens examined the influence of various environmental conditions on their mechanical proper-ties such as stress-strain characteristics and bond between FRP and FRP. Results to-date indicate that the exposure to most of the environmental conditions has minimal effects on the properties tested during this experimental program. Freeze-thaw cycles and moisture exposure seemed to be the two environmental conditions with noticeable effects on the bond properties of single lap bonded specimens.