Steel rebars have long been used to reinforce concrete in construction projects. However, an alternative reinforcement option is gaining popularity for its many benefits, such as glass fiber-reinforced polymer (GFRP) rebar.
What is GFRP rebar?
GFRP rebar is a composite material of glass fibres embedded in a polymer matrix. The glass fibres provide stiffness to the rebar, while the polymer matrix binds the fibres together and protects them from damage. GFRP rebar is manufactured through pultrusion, where the glass fibres are pulled through a resin bath and through a heated die to cure the polymer.
Benefits of GFRP rebar over steel
Several key advantages make GFRP rebar a superior alternative to traditional steel rebar:
- Corrosion resistance: Rebar made of steel is susceptible to corrosion in harsh environments such as coastal regions or regions with de-icing salts. As steel corrodes, it expands and causes the surrounding concrete to crack and deteriorate. In contrast, GFRP rebar is highly resistant to corrosion. It does not rust or degrade even when exposed to moisture, chemicals, or extreme temperatures. This corrosion resistance translates to longer service life and reduced maintenance costs for concrete structures reinforced with GFRP.
- High strength-to-weight ratio: GFRP rebar has a much higher strength-to-weight ratio than steel. It is about one-fourth the weight of steel rebar but has a tensile strength equal to or greater than steel. This lightweight property makes GFRP easier and faster to transport and install. It also reduces the overall dead load on a structure.
- Low thermal and electrical conductivity: Unlike steel, GFRP neither conducts heat nor electricity. This is advantageous in applications where thermal or electrical conductivity could be problematic, such as in facilities housing sensitive electronic equipment or structures exposed to lightning strikes. The low conductivity of GFRP also eliminates the risk of galvanic corrosion that occur when dissimilar metals are in contact.
- Electromagnetic transparency: GFRP rebar is transparent to electromagnetic signals, making it ideal for use in structures that house MRI machines, radar equipment, or broadcast antennas. Steel rebar can interfere with these signals.
- Durability in extreme environments: GFRP maintains its structural properties even when subjected to extreme temperatures, humidity, and chemical exposure. It does not become brittle in cold temperatures like steel can.
Applications of GFRP rebar
The unique properties of GFRP make it well-suited for a variety of construction applications:
- Bridge decks and other transportation infrastructure exposed to de-icing salts
- Marine structures like piers, seawalls, and offshore platforms
- Parking garages and other structures exposed to high humidity and moisture
- Facilities housing sensitive electronic equipment
- Architectural concrete like decorative facades and sculptures
- Temporary concrete structures that will be removed or demolished
Despite its many benefits, GFRP rebar has yet to be as widely used as steel rebar. One reason is its higher initial cost. However, the lifecycle cost of structures reinforced with GFRP is often lower due to reduced maintenance and repair needs. As more architects, engineers, and contractors become aware of the superior performance of GFRP, its use is expected to grow.
