Thermal and environmental effects on fiber-reinforced polymer reinforcing bars and reinforced concrete elements

Abstract

Corrosion of steel reinforcement in bridge decks results in high repair costs, unwanted traffic disruption, and unsafe structures. To help alleviate this problem, non-metallic fiber-reinforced polymer (FRP) bars are being studied as an alternate type of reinforcement in bridge decks. In order to determine the suitability of the use of FRP bars, a number of tests have been performed on FRP bars to evaluate their long-term performance. These tests include uniaxial tension tests under a variety of environmental conditions and thermal expansion of the bars embedded in concrete. In an effort to characterize the FRP bars and to gain insight into their long-term performance, batteries of tests have been carried out. Samples from three different manufacturers were exposed under different environmental conditions and tested in uniaxial tension. For one of the bar types, the strength increased, while the other two bar types lost strength. In all cases, the modulus of the bars increased with exposure time. In addition, FRP reinforced concrete specimens were evaluated for thermal expansion. The results indicate that thermal cracking of the concrete by FRP bar expansion is not a significant problem.