Fiber is used to reinforce concrete in two ways – as chopped fiber filler and as composite rebar.
FRP (Fiber Reinforced Polymer) Rebar
Reinforced Concrete is a very common building material for the construction of facilities and structures. As complement to concrete's very limited tensile strength, steel rebar has been an effective and cost-efficient reinforcement. However, insufficient concrete cover, poor design or workmanship, and presence of large amounts of aggressive agents including environmental factors all can lead to cracking of the concrete and corrosion of the steel rebar. For instance, in the USA, almost 40% of bridges are structurally deficient or functionally obsolete, and the percentage is increasing, according to the Federal Highway Administration (Griffiths 2000). For many years, there have been many studies on this corrosion issue, and the interest in FRP has arisen recently as prospective substitute for steel. Careful consideration on potential of FRP rebar to fill the cost and performance needs may suggest appropriate solutions.
Fiberglass reinforced plastic (FRP) composite rebars are produced by combining the pultrusion process and an inline winding and coating process for the outside sand surface. The FRP composite rebar is made from high strength fiberglass and basalt fiber along with an extremely durable vinyl ester or epoxy resin. The glass fibers impart strength to the rod while the resin imparts excellent corrosion resistance properties in harsh chemical and alkaline environments.
FRP rebar significantly improves the longevity of civil engineering structures where corrosion is a major factor.
Features and Benefits:
Corrosion-resistance: Will not rust, and are impervious to the action of salt ions, chemicals, and the alkalinity inherent in concrete.
Lightweight: Weigh approximately one-quarter the weight of an equivalent size steel bar, offering significant savings in both placement and use.
Electromagnetic neutrality: Contain no metal, and will not interfere with the operation of sensitive electronic devices such as medical MRI units or electronic testing devices.
Thermal insulator: Highly efficient in resisting heat transfer, such as from building exteriors to interiors.
Excellent Fatigue Resistance: Performs very well in cyclic loading situations.
High tensile strength: Better than the one of steel rebar.
High bond strength: Better than steel-to-concrete bonding.
FRP composite rebar has cost effective application as a concrete reinforcing bar in the following markets when analyzed on a life-cycle cost basis:
- Road construction;
- Bridge construction;
- Railway station;
- Civil building;
- Undergroud engineering;
- Sewage treatment plant;
- Chemical plant;
- Electrolytic bath;
- Manhole cover;
- Reinforced concrete exposed to deicing salts;
- Retaining walls and foundations;
- Swimming pools;
- Applications subjected to other corrosion environment.
Density - 1.95 g/cm3
Thermal conductivity - 0.3 Kcal/m.h.deg
Tensile Strength : 1200 Mpa
Compression Strength : 420 Mpa
Bending Strength : 800 Mpa
Density : 2600/2800 kg/m3
Mass fraction of the polymer binder - 20/24%