Long-Term Performance of GFRP Tubes Filled with Concrete and Subjected to Salt Solution

Abstract

This paper presents mechanical, microstructural, and physical characterization of aged glass fiber-reinforced polymer (GFRP) tubes used in the concrete-filled fiber-reinforced polymer (FRP) tube (CFFT) system for bridge columns and marine pile applications, or used hollow as tubular poles or in pipelines. The main objective of the study is to evaluate the durability and predict the long-term behavior of the filament-wound GFRP tubes. CFFTs were exposed to salt solution at 23, 40, and 50°C for 365 days to accelerate the environmental effect. Given the significance of confinement in a CFFT system, the measured hoop tensile strength of the tube before and after exposure was considered the primary indicator of durability performance of the specimens. In addition, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the aging effect on GFRP tubes. Test results showed that the GFRP tubes investigated in this study, and exposed to a rather aggressive environment, performed well. The reduction in hoop tensile strength at the end of exposure ranged from 11 to 21%, depending on temperature. Using the Arrhenius theory, the predicted reduction in strength after 100 years at a mean annual temperature of 6°C, representing some northern regions, was estimated at approximately 32%.