GFRP Rebar Glossary

Plain-English definitions of the key terms used across our GFRP rebar product, application, and technical pages.

FRP (Fiber Reinforced Polymer)

FRP, or Fiber Reinforced Polymer, is a composite material made by embedding fibers — glass, carbon, basalt, or aramid — in a polymer resin matrix. FRP composites are used across construction to reinforce concrete, strengthen existing structures, and replace metal components in corrosive or electrically sensitive environments. GFRP, CFRP, and BFRP rebar (defined below) are all types of FRP reinforcement.

GFRP (Glass Fiber Reinforced Polymer)

Glass Fiber Reinforced Polymer (GFRP) rebar is an FRP composite reinforced with glass fibers and bound in a polymer resin. It is the most common and cost-effective FRP rebar type for concrete reinforcement, valued for its corrosion resistance, light weight, high tensile strength, and non-conductive properties. Ramani Composites manufactures GFRP rebar for bridges, marine structures, industrial floors, and other infrastructure projects.

CFRP (Carbon Fiber Reinforced Polymer)

Carbon Fiber Reinforced Polymer (CFRP) is an FRP composite reinforced with carbon fibers instead of glass. CFRP offers very high tensile strength and stiffness (a higher elastic modulus than GFRP), but at a significantly higher cost. It is more commonly used for structural strengthening and repair (e.g. externally bonded strips) than as primary concrete rebar.

BFRP (Basalt Fiber Reinforced Polymer)

Basalt Fiber Reinforced Polymer (BFRP) is an FRP composite reinforced with fibers made from melted volcanic basalt rock. BFRP offers good chemical and high-temperature resistance and sits between GFRP and CFRP in terms of mechanical properties and cost, though it is less widely available than GFRP for standard concrete reinforcement.

Rebar (Reinforcing Bar)

Rebar is a bar embedded in concrete to provide the tensile strength that plain concrete lacks on its own. Traditional rebar is made of carbon steel, but steel corrodes when exposed to moisture, chlorides, or chemicals, eventually cracking the surrounding concrete. GFRP rebar is a corrosion-resistant, non-metallic alternative designed to serve the same structural role.

Tensile Strength

Tensile strength is the maximum stress a material can withstand while being stretched or pulled before it fails or breaks. It is one of the primary properties used to compare reinforcement materials: GFRP rebar generally offers higher tensile strength than conventional steel rebar of the same diameter, though the two materials behave differently under load (see Elastic Modulus below).

Elastic Modulus

The elastic modulus (or modulus of elasticity) measures how much a material deforms elastically — and returns to its original shape — under stress, in other words its stiffness. GFRP rebar has a lower elastic modulus than steel, meaning it flexes more under the same load. This property must be accounted for in structural design, particularly for deflection and crack-width control, and is addressed in design codes such as ACI 440.1R.

Alkali Resistance

Alkali resistance describes a material's ability to withstand the naturally high-alkaline (high-pH) environment inside cured concrete without degrading. This is an important long-term durability factor for FRP rebar, since the resin and glass fiber system must resist alkali attack over the structure's design life. Reputable GFRP rebar is manufactured with resin systems and fiber sizing specifically formulated for alkali resistance in concrete.