Effects of fiber reinforced polymer (FRP) wrap on reducing chloride penetration in concrete

The objective of this study was to investigate the effects of FRP wrap on reducing chloride penetration in concrete. It has been established that FRP wrap used to retrofit concrete structures offer a high resistance to chemical solutions. The ACI 318-11 Code allows for a reduction of clear cover depth if an equivalent clear cover depth can be establish. The FRP material used herein consisted of Tyfo SCH-41 and Tyfo SEH-51A composites fabricated from carbon and glass fibers, respectively. The wrapped FRP concrete specimens and control specimens without FRP wrap were tested according to ASTM C 1543 and ASTM C 1152 specifications. A sodium chloride solution was used to expose the surface of the concrete and FRP composite materials for a period of six weeks. At the end of chemical exposure, small powder samples were collected from various depths in order to determine the level of chloride in each specimen. Results obtained indicate that both FRP composite materials resulted in significant reduction of chloride in the concrete. The decrease in chloride content was maximum near the surface and reduced with depth. Equivalent clear cover depths for the FRP samples were determined that would result in similar chloride ingress and possible steel corrosion. The cover reductions can range between 16% - 26% for beams and 44% - 50% for slabs, based on the FRP type. The reduced equivalent clear covers can lead to increased load capacity of the concrete members. Likewise, the FRP application may be used to satisfy existing unacceptable clear cover values in older structures compliant to current Code provisions.