Glass Fiber Reinforced Polymer (GFRP) in Infrastructure Applications – from a layman’s perspective

Is this the first time you are reading about GFRP?

Well, Fiber Reinforced Polymer (hereafter called FRP) is not something invented recently. A little digging in the history book shows that the roots were conceived in the late 1930s in the USA and there were many experimental and demonstrative projects conducted in the USA and Europe thereafter. It was the Japanese people who introduced design guidelines for GFRP in 1996 which served as a good foundation for many upcoming versions of codes and guidelines.  Although it has been used extensively now in applications such as storage tanks, wind turbine blades, boats, pipes, aircraft fuselage etc but the commercial use of GFRP products for permanent usage in infrastructure projects is still “novice in the field” at least in developing economies like India. The applications mentioned above will see FRPs in various shapes and product forms but for Infrastructure applications, we will mainly discuss about solid round profiles like rebars, bolts, anchors etc

The Composition

The FRP products are essentially made of Fibers impregnated with polymeric Resins. It’s the fiber which determines the strength of the product and Resin binds these fiber elements together, enabling the load transfer from one fiber element to another with the additional duty of protecting it. There exists various forms of FRPs based on which type of fiber is used like Carbon, Aramid, Basalt etc but we will limit our discussions to the Glass Fiber which is used extensively in infrastructure projects.

On the other hand, choosing the right type of resin is of extreme importance as this will have a direct impact on the mechanical and long term properties of the GFRP system and application under consideration. The basic option available with resins could be thermoplastic (which could be reshaped using temp cycles) or thermosetting (which generally does not change the shape when heated unless decomposed at high temps). Again, our area of interest is thermosetting resins only and the examples of which are Epoxy, Polyesters and Vinyl Ester (Most Preferred).

The most common and popular method of manufacturing FRP is the Pultrusion process in which fiber filaments are pulled from the roving to undergo resin bath & then cured in a heated die with necessary surface preparation (sand coating or surface deformations etc)

Key Reasons why GFRP is arguably best replacement of Steel in Infrastructure Projects

The infrastructure industry has long relied on steel as a fundamental material, known for its strength and versatility. However, as projects increasingly demand materials that offer both high performance and sustainability, Glass Fiber Reinforced Polymer (GFRP) is emerging as a compelling alternative.

1. Corrosion Resistance

One of the major limitations of steel is its susceptibility to corrosion, particularly in harsh environments such as coastal areas, underground, or chemical plants. Steel structures exposed to water, salt, and chemicals require regular maintenance to prevent rust, which leads to increased operational costs over time.

GFRP, on the other hand, is inherently corrosion-resistant. Being a non-metallic composite material, it does not rust or degrade in aggressive environments, reducing maintenance requirements significantly. This property makes GFRP particularly useful in marine applications, chemical plants, water treatment facilities, and underground structures where corrosion is a persistent challenge.

2. High Strength-to-Weight Ratio

Steel’s high density, while a benefit in terms of strength, is also a drawback when weight is a concern. The weight of steel can impose limitations on design, increase transportation costs, and complicate installation processes.

GFRP, however, offers a superior strength-to-weight ratio. It is as strong as steel but significantly lighter, making it easier to transport, handle, and install. This property is crucial in applications like bridge decks, tunnels, and high-rise buildings, where reducing weight can also reduce structural loads, leading to overall cost savings in construction and engineering design.

3. Electrical and Thermal Insulation

Steel, being a good conductor of electricity and heat, requires insulation in certain applications to prevent accidents or inefficiencies. In contrast, GFRP is a natural insulator. Its electrical non-conductivity makes it ideal for use in power plants, electrical substations, and other environments where electrical safety is paramount. Additionally, GFRP has low thermal conductivity, offering thermal insulation benefits, which are valuable in energy-efficient building designs and in industries where temperature control is critical.

4. Durability and Longevity

The inherent corrosion resistance and chemical inertness of GFRP contribute to its long service life, even in the most demanding environments. While steel structures need frequent maintenance and corrosion protection treatments, GFRP structures typically last longer without major intervention. This longevity makes GFRP a more cost-effective solution over the lifecycle of the structure.

6. Sustainability

Sustainability has become a priority for the infrastructure industry, with increasing focus on reducing carbon footprints. Steel production is energy-intensive, contributing significantly to carbon emissions. GFRP, however, offers a more environmentally friendly alternative. It requires less energy (~40%) & emits less carbon (~60%) during manufacturing and transportation, thanks to its lightweight properties. Additionally, GFRP’s longer service life reduces the need for frequent repairs and replacements, contributing to sustainable construction practices.

Another very interesting concept promoting sustainability is the SEA-SAND SEAWATER CONCRETE (SSC) which has a direct impact in the reduction of CO2 from the concrete itself. SSC is essentially a combination of GFRP Rebars – Sea sand and Seawater – Recycled Concrete Aggregates. Dextra is a member of “ACI Committee 243 – Seawater Concrete” which is preparing a Guide to the Use of Seawater-Mixed Concrete.

Code & Design Guidelines

1. International

1. ACI 440.11.22 (Building Code Requirements for Structural Concrete Reinforced with GFRP Bars and Commentary)
2. Eurocode 2 (Annexure R for FRP rebars)
3. CSA S 806 (2021)

2. India

1. IS 18255:2023 (Methods of Test)
2. IS 18256:2023 (Technical Specifications)
3. IRC:137-2022 (Guidelines)

Indicative list of GFRP Applications in Infrastructure Projects

1. Tunnels –

1. Permanent Rock bolts for NATM Tunnels
2. Rebar + MS Fiber in TBM reinforcement, Soft eye in TBM Tunnel

2. Roads & Bridges –

1. Rebar for deck of the bridge
2. Soil nail for Slope stabilization applications
3. Rebars replacing permanent steel works like trenches, anti-crash barriers etc

3. Urban Rail –

1. Anchors for UG works

4. Marine Ports –

1. Rebars for Repair Work, Sea Walls, Flat work applications

5. Miscellaneous projects such as Warehouses, Cold Storages, Industrial Slabs, Flood Channel etc

Dextra India
215 Atrium 2, Tower 2, Ground Floor, Unit no. 001, Andheri – Kurla Road, Hanuman Nagar, Andheri East 400059, Mumbai, India.
Phone: +91 22 2838 6294 ext 217 / +91 96199 06565
Email: bjog@dextragroup.com
Website: https://www.dextragroup.com/