Durability of Glass and Basalt Fibre Reinforced Polymer rods in low carbon concrete

Fiber-Reinforced Polymer (FRP) bars have emerged as a promising alternative to conventional steel reinforcement in the construction industry due to their superior durability performance. FRP bars exhibit non-corrosive properties, effectively addressing the primary issue of steel corrosion-induced degradation in concrete structures. Steel corrosion can lead to prohibitive repair costs in civil infrastructure and brittle catastrophic failures (e.g., the collapse of Morandi bridge). Despite the corrosion-free nature of FRP rods, their matrix/resin component plasticises when exposed to humid conditions (e.g., at a concrete crack location) and degrades due to chemical attack. This is more critical for matrix dominated properties of concrete structures reinforced with FRP bars such as the bond, shear and transverse compressive strength of FRPs. This project focuses on a comprehensive examination of the long-term performance of Glass Fiber Reinforced Polymer (GFRP) and Basalt Fiber Reinforced Polymer (BFRP) bars under various environmental conditions by simulating aggressive environmental conditions, including elevated temperatures, saline, and alkaline exposures, to evaluate the performance of GFRP and BFRP bars.

The project aims to create a test protocol that correlates FRP durability performance under accelerated ageing conditions and short-term exposures with actual on-site conditions. Key variables of interest are resin dominated properties in of FRPs and effect of stress conditions. This test protocol will shed light on the reliability of commonly applied accelerated ageing tests adopted in lab conditions. The test protocol is adopted for both resin samples and FRP bars to obtain an in-depth understanding of how the individual constituents, fiber, matrix perform but also the FRP system performs accounting also for fiber-matrix interfaces. The potential incorporation of FRP bars under applied stresses adds a crucial dimension by examining their degradation properties when subjected to load-bearing conditions while exposed to aggressive environments, closely mimicking real-world applications.

FRP bars will be examined after being exposed to normal and accelerated conditions to be tested to measure their interlaminar and transverse shear strength. Non-exposed and pre-exposed FRP bars will be cast in concrete beams and blocks to measure the effect of exposure degradation on the bond and flexural performance of FRP bars in concrete structures. Resin samples will be cast, exposed, and tested separately to see the effect of direct exposure to pure resin samples after being tested in tension and shear. The type of exposure that will be used to understand the acceleration effect of the used protocol will be by comparing the degradation effect of directly exposed FRP samples in an alkaline mixture that replicates the pH and chemistry of concrete but at elevated temperatures to increase the diffusion to the composite material.

The outcomes of this project offer wide-ranging benefits to the construction industry and sustainability endeavors:

a. Enhanced Infrastructure Durability: The development of FRP bars with improved long-term performance can extend the lifespan of concrete structures, resulting in reduced maintenance costs and enhanced sustainability.

b. Advancing Net-Zero Construction: The utilization of low carbon concrete reinforced with FRP bars aligns seamlessly with the UK's net-zero emissions targets, making this research directly relevant to sustainability goals.

c. Industry-Wide Adoption: The newly established acceleration protocol can be readily adopted across the construction industry to assess the durability of FRP bars, ensuring the reliability and safety of construction projects.

This project delves into the promising realm of Fiber-Reinforced Polymer (FRP) bars as a durable alternative to traditional steel reinforcement in construction while working towards more sustainable and durable approaches.