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  • Writer's pictureNed Patton

Composites in Infrastructure 3 - Putting the Building Blocks Together

Bridges, pipes in desalination and chemical process plants, covers for huge water storage tanks, even ferry docks that are made to last 100 years or more. Composites are making their appearance in infrastructure projects all over the world. The light weight, longevity, and low cost of composites, both for the raw materials and installation costs have gotten to the point where the replacement of steel and concrete with what is called FRP – fiberglass reinforced plastic – has become almost commonplace.

While the use of composites in infrastructure projects is still in its infancy, there are a couple of laws passed by Congress recently that are going to help in the future. As of the end of 2021, only about 1% of infrastructure projects used composites, according to Composites World (

In August of 2020, Congress passed the “Composites Standards Act” which funded NIST and NSF to develop a clearinghouse for standards for composites to be used in infrastructure projects. This includes durability testing for proposed material systems along with education and training. This training is intended to retrain workers who are used to working in steel to understand how to put together things like the composite truss bridge shown to the right here.

The clearinghouse for information is the first tangible step to the development of standards for composites use in infrastructure development to replace traditional materials like steel and concrete. There are of course well established standards for both steel rebar and concrete that have been used for nearly 100 years, but no established standards for composites.

I included pictures of fiberglass rebar again this week because of the importance of this one single, simple application of composites to infrastructure. It is arguably the most prevalent example of the use of composites in infrastructure – primarily because of the unmatched strength, life expectance, and zero maintenance afforded by the use of fiberglass instead of steel.

The main point that I wanted to get across in the pictures in this post is that composite materials are starting to be used in ways that even as little as 10 years ago would have been unheard of. The bridge in the pic to the left is a classic example of this. Composites have enabled the construction of the underpinnings of that bridge to be installed using a readily available crane. If that were made using concrete and steel, the labor itself to build the forms, lay in and tie the steel, and pour the concrete would have taken months. Instead, using a pre-made composite structure allowed this bridge frame to be installed in a day. And, using a composite material bridge deck like what was installed in the truss bridge pic above made this job affordable and very easy to build.

The marine ferry terminal shown in the top pic is another example of composites being used in the place of traditional materials. The terminal is for the St. Johns River Ferry in Jacksonville, FL. Traditional materials for these sorts of marine structures are steel and concrete pilings and guide walls. Apparently the wind is pretty aggressive at this ferry landing, as are the currents, so the Ferry Guide Wall takes quite a beating and needed to be replaced every few years. The original steel and concrete pilings and guide wall took quite a beating from hard landings as well as corrosion in the marine environment. So, a company by the name of Coastline Composites built FRP pilings and reinforced HDPE (High Density PolyEthylene) guide walls (the yellow and black stuff) and reinforced parts of the pilings and guide walls with FRP rebar to make a Ferry Guide Wall that would last. The inherent flexibility and toughness of these materials made all the difference.



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