• Mark Turnquest, CIPM

Glass Fiber Rebar/Steel Use

What Is Glass Fiber Reinforced Polymer Rebar?

Glass Fiber Reinforced Polymer is a type of synthetic reinforcement that has been challenging the market dominance of steel rebar since the 1990s. It’s composed of continuous glass fibers, which are encased in a polymeric resin.

Due to its composition, fiberglass rebar offers construction several advantages. Below, we’ll discuss 3 of the most consequential advantages of GFRP — resistance to corrosion, low weight, and high strength.

1. Full Corrosion Resistance

One major advantage of GFRP reinforcement is its resistance to corrosion. Since GFRP does not contain any iron, it’s inherently corrosion-proof — there’s no possibility of a chemical reaction occurring that would degrade the rebar.

2. Lower Weight

Construction crews will celebrate this one. Whereas steel rebar has a unit weight of 487 pounds per cubic foot; meanwhile, its GFRP counterpart weighs in at only 131 pounds per cubic foot.

3. Greater Strength

If you think that lower unit weight has any impact on GFRP’s strength, think again. GFRP boasts higher tensile and compressive strengths and greater fatigue strength than steel rebar.

4.Tensile Strength

GFRP has a tensile strength of 1275-10,000 MPa — which is more than steel’s 450 MPa.

What’s more, GFRP doesn’t lose any of the tensile strength in extreme temperatures, whereas steel rebar can become brittle in severe cold.

5.Compressive Strength

GFRP has a slight edge in compressive strength over steel, boasting roughly 550MPa over steel rebar’s 400MPs. This statistic is less significant compared to tensile strength, which is the primary purpose of concrete reinforcement, but still worth mentioning.

Fiberglass rebar has proven to outperform steel in its resistance to cyclic loading (aka fatigue strength). A cyclic load is a load that gets applied and removed over and over again; this type of load can cause rebar to fail, possibly leading to a complete failure of the structural element in which the rebar is present.

An earthquake is a great example of a cyclic load, and a notable cause for concern, since rebar provides the ductility concrete buildings need to withstand seismic forces without collapsing.