Effect of tensile modulus of GFRP on shrinkage and temperature reinforcement requirements in liquid containing structures

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Fiber reinforced polymers (FRP) are composite materials made of fibers embedded in a polymeric resin. They were introduced as an alternative replacement for steel reinforcement. Electromagnetic interface and steel corrosion could be prevented by FRP reinforcement due to their nonmagnetic and non-corrosive nature. There has been a widespread use of fiber reinforced polymers (FRPs) as reinforcing composite bars for concrete structures over the past decade. Other than being corrosion resistant, there are many advantages of using such reinforcing bars especially glass FRPs (GFRPs) over the conventional reinforcement due to enhanced properties, cost-effectiveness, among many others. For structures exposed to aggressive environmental situations including liquid containing structures (CLCS) and marine structures, the alkalinity of concrete is reduced by its exposure to salts, moisture, temperature and chlorides leading to steel corrosion. The process of corrosion will lead to concrete deterioration and lack of serviceability. In order to prevent corrosion and deterioration, engineers started using epoxy-coated bars and GFRPs later on. Using GFRP as a replacement for steel reinforcement for CLCS is a fairly new topic. Both Canadian and American standards for design of FRP reinforced structures (CSA S806-12 and ACI 440.1R-06) briefly mention on the minimum reinforcement for controlling temperature and shrinkage reinforcement. A comprehensive study is proposed here to address this issue. This study is aimed to investigate the parameters that influence the temperature and shrinkage reinforcement and in particular the effect of different types of GFRPs in terms of tensile modulus. It is also proposed to provide guidelines for structures reinforced with GFRP bars to limit the crack width to an acceptable level.