Durability of GFRP Reinforcing Bars Embedded in Moist Concrete

TLDR

The study characterizes the durability of GFRP reinforcing bars in concrete by examining mechanical, microstructural, and physical changes under simulated concrete conditions. GFRP bars were embedded in concrete and exposed to tap water at 23, 40, and 50 °C, with tensile strength measured before and after exposure and analyzed via Arrhenius theory, while FTIR, DSC, and SEM characterized aging effects. Durability of mortar‑wrapped GFRP bars was less impacted by accelerated aging than bars exposed to simulated pore‑water, confirming that laboratory alkaline‑solution studies overestimate durability concerns for concrete service life.

Abstract

This paper presents mechanical, microstructural, and physical characterization of glass fiber-reinforced polymer (GFRP) bars exposed to concrete environment. GFRP bars were embedded in concrete and exposed to tap water at 23, 40, and 50°C to accelerate the effect of the concrete environment. The measured tensile strengths of the bars before and after exposure were considered as a measure of the durability performance of the specimens and were used for long-term properties prediction based on the Arrhenius theory. In addition, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy were used to characterize the aging effect on the GFRP reinforcing bars. The results showed that the durability of mortar-wrapped GFRP bars and exposed to tap water was less affected by accelerated aging than the bars exposed to simulated pore-water solution. These results confirmed that the concerns about the durability of GFRP bars in concrete, based on simulated laboratory studies in alkaline solutions, do not properly correspond to the actual service life in concrete environments.