Deicing salts are often used to dissolve ice and snow when Reinforced Concrete (RC) bridge decks are exposed to a freezing environment that any structural element experience. On the other hand, it is impossible to effectively eliminate the cracking in concrete, which will cause corrosion problem of steel reinforcement in concrete because the cracks allow the chlorides from deicing chemicals to infiltrate the concrete and break down the protective alkalinity layer around the reinforcing bars and allow oxygen and moisture to initiate the corrosion process. Use of Fiber Reinforced Polymer (FRP) materials improves this problem due to their higher resistance to corrode. However, a number of researchers report that there are some losses of tensile strength when Glass Fiber Reinforced Polymer (GFRP) bars are embedded in concrete. Others state that there is not any sign to indicate the corrosion of GFRP bars when physical and chemical composition of GFRP bars at the microscopic level are analyzed. Therefore, in this paper, tensile test, optical microscopic image analysis, and Scanning Electron Microscope (SEM) analysis of GFRP bars were conducted to investigate whether GFRP bars are deteriorative. The results illustrated that tensile strength of GFRP bars was lower than the value reported by manufacturer. There were limit results to illustrate degradation of GFRP bars after long-term field exposure to concrete by analyzing the microstructure of GFRP samples. Therefore, more microstructural analysis will be required.