Use of FRP Composites in Bridges
FRP (Fiber Reinforced Composites) have been successfully used in the construction and repair of transportation bridges in the U.S. for several years. These projects have proven that the materials and work methods are can be successfully used.
FRP rebar can replace steel rebar and provide equal physical strength while eliminating the corrosion problems of having steel embedded in concrete.
Prefabricated bridge decks made of FRP in a factory can be quickly and easily installed in the field to save time and money during the bridge construction project. The large panels are shipped in and laid down, ready to use very quickly. Concrete cure and inspection times are reduced.
Concrete crack repairs can be made to bridges and concrete structures by wrapping them with composite materials to seal these cracks and hold the concrete together, protecting it from further damage.
This technology has been in development for many years, and proper materials, construction techniques, and design guidelines have been established to allow for many successful projects to be completed.
Economics play a considerable role, and this cost comparison constantly changes with the prices of materials on both sides. Composites have the advantage of typically requiring fewer road closures and construction time in the field.
Infusion-Test Panel and Fuselage
Ran across an interesting Youtube video demonstrating an epoxy resin infusion process on some test panels and fuselage. It is interesting how everybody has their own terminology and technique for resin infusion. There is definitely more than one way to get the job done.
They use an interesting layup, including lots of the Soric material. I have used this before, and it is a good material to infuse with. Made by a company called Lantor, it is a non-woven polyester material that acts as a core material. It appears that the folks in the video are using the SF grade Soric, which comes in several thicknesses.
An advantage of using Soric as a core is that it flows resin very well for infusion. It is easy to cut and handles well.
Disadvantages also abound. One of them is the possibility of print-thru on the surface of the laminate. Another is the negative effect on the structural properties of the laminate. This non-woven material does not have much crush resistance such as a balsa or foam material. A serious issue that I have found is the higher risk of delamination. Like any core, this material works by separating the two skin layers to create a sort of “I beam” effect. The problem is that this material is not inherently strong within itself. Though it does become saturated with resin during a proper infusion, it is not nearly as strong as glass or carbon fiber reinforcement.
As the video demonstrates, a proper resin infusion can look easy. With proper materials, practice, and knowledge it can be.
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