Durability of GFRP reinforcing bars in seawater concrete

Abstract

This paper presents an experimental study that investigated the durability performance of unstressed glass fiber-reinforced polymer (GFRP) bars embedded in concrete mixed with seawater (seawater concrete). GFRP bars were extracted from concrete elements made with two different seawater concrete mix designs and exposed to different environmental conditions for 1, 6, 12, and 24 months. The concrete samples’ exposure environments consisted of typical field conditions of a subtropical region and seawater at 60 °C as an accelerated aging method. The mechanical test results of GFRP bars are reported in residual capacities of tensile strength, longitudinal elastic modulus, transverse shear strength, and apparent horizontal shear strength. Furthermore, the physical evaluations are in terms of glass transition temperature (Tg) and microstructural integrity through scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) analysis. Among all tested properties, tensile strength was the most affected by environmental conditioning. Based on an exponential degradation model, the long-term prediction of the tensile strength capacity was on average 92% under typical field exposure and 72% under the more aggressive conditioning (seawater at 60 °C).