Evolution of FRP reinforcement
In the 1960s corrosion problems began to surface with steel reinforced concrete in highway bridges and structures.
Road salts in colder climates or marine salt in coastal areas accelerated corrosion of the reinforcing steel.
Corrosion products would expand and cause the concrete to fracture. The first solution was a galvanized coating applied to the reinforcing bars.
This solution soon lost favor for a variety of reasons, but mainly because of an electrolytic reaction between the steel and the zinc-based coating leading to a loss of corrosion protection.
(ACI 440R, 1996) In the late 1960’s severalcompanies developed an electrostatic-spray fusion-bonded (powdered resin) coating for steel oil and gas pipelines.
In the early 1970s the Federal Highway Administration funded research to evaluate over 50 types of coatings for steel reinforcing bars.
This led to the current use of epoxy-coated steel reinforcing bars.
Research on use of resins in concrete started in the late 1960s with a program at the Bureau of Reclamation on polymer-impregnated concrete.
Unfortunately, steel reinforcement could not be used with polymer concrete because of incompatible thermal properties.
This fact led Marshall- Vega (later renamed Vega Technologies and currently reformed under the name Marshall-Vega Corporation) to manufacture a glass FRP reinforcing bar.
The experiment worked and the resultant composite reinforcing bar became a reinforcement-of-choice for polymer concrete.
In spite of earlier research on the use of FRP reinforcement in concrete, commercial application of this product in conventional concrete was not recognized until the late 1970s.
At that time, research started in earnest to determine if composites were a significant improvement over epoxy-coated steel.
During the early 1980s, another pultrusion company, International Grating, Inc., recognized the product potential and entered the FRP reinforcing bar industry.