Combined Effect of Moisture and Temperature on Concrete Cover Surrounding GFRP Bars

In the last decade, fiber reinforced polymer (FRP) has become the best solution to the problem of corrosion in reinforced concrete structures. However, more detailed investigation of the thermal behavior of FRP bars embedded in wet concrete is required to avoid splitting failure of concrete cover of reinforced concrete structures immersed in water under temperature. This paper presents an experimental study to investigate the combined effect of moisture and temperature on the behavior of FRP bar and concrete cover using concrete cylinder specimens reinforced with glass FRP (GFRP) bars immersed in water and subjected to temperatures varying from -30 to +80 degrees C. The experimental results show that immersion in water at high temperature can damage the bond between GFRP bar and concrete. The temperatures required to produce splitting failure of concrete cover for concrete cover thickness to FRP bar diameter ratio (c/d(b)) less than or equal to 1.5 immersed in water are between 50 and 60 degrees C, similar to those for specimens not immersed in water. Also, moisture has no significant influence on the thermal behavior of concrete cover surrounding GFRP bar for temperatures up to 60 degrees C. A comparison between the predicted and experimental transverse thermal strains is presented. The results show good agreement for temperatures up to 60 degrees C.