A new, lightweight reinforcement material is poised to transform the civil engineering and construction industries by offering a superior alternative to traditional steel rebar. Researchers at the University of Maine’s Advanced Structures and Composites Center (ASCC) are pioneering the development of fiber-reinforced thermoplastic polymer (FRTP) rebar, a composite material designed to overcome steel’s critical limitations, including its susceptibility to corrosion, weight, and high life-cycle costs. This material enhances the structural integrity and longevity of concrete infrastructure while significantly lowering both maintenance costs and environmental impact.
The material, at just 25% the weight of steel rebar, reduces transportation costs and a project’s overall carbon footprint. Additionally, the ability for FRTP Rebar to be bent on-site gives engineers and contractors a new level of flexibility currently available from current composite rebar options, while its recyclability and low-impact processing offer a more sustainable alternative to traditional construction materials.
The research, recently published in the Journal of Composites Science titled “Continuously Formed Fiber-Reinforced Thermoplastic Composite Rebar for Concrete Reinforcement,” by UMaine and ASCC researchers Jacob Clark, William Davids, Roberto Lopez-Anido, Andrew Schanck and Cody Sheltra, addresses the flexibility and durability challenges of rebar used in concrete structures. While steel rebar is strong and ductile, it is prone to corrosion, heavy, costly to transport, and has a large carbon footprint. Though commercially available fiber-reinforced rebar made with thermoset polymers addresses some of these challenges, it cannot be bent on-site like steel rebar, which is a significant limitation. Fiber-reinforced thermoplastic polymer (FRTP) rebar, however, possesses the advantages of thermoset FRP rebar and can be field-bent, greatly increasing construction flexibility. Further, in contrast with thermoset FRP rebar, FRTP rebar offers greater potential for recyclability, can be made from recycled resins, and does not produce harmful emissions during processing.
Constructed and researched using the ASCC’s novel pultrusion device, the Continuous Forming Machine (CFM) is used to fabricate FRTP rebar from commercially available thermoplastic tape. Developed at UMaine, the CFM can manufacture complex thermoplastic FRP parts for a variety of applications which benefit from its high corrosion resistance and lightweight, including transportation, construction, and infrastructure. Through a patented pultrusion process, the CFM can create 12ft/min of #4 (1/2 inch) FRTP rebar.
The Continuous Forming Machine.
Working closely with State Departments of Transportation the ASCC is continuing development and manufacturing of novel, corrosion-resistant, rapidly deployable infrastructure components designed with composite materials to assess and enhance the longevity of existing transit infrastructure. The ASCC is also testing rapidly deployable bridges, girders, breakwaters, and culvert diffusers in the field to showcase their real-world performance and prepare them for wider use in critical transportation networks.
ReForm Composites, an ASCC spinoff company, is working to bring FRTP rebar to the commercial market. Scaling production beyond research would enable widespread adoption in bridges, highways, and other reinforced concrete applications, addressing the industry’s need for corrosion-resistant, adaptable solutions.
This work aligns with the Advanced Research Projects Agency – Infrastructure (ARPA-I) mission to accelerate transportation projects that improve the safety, durability, and longevity of the nation’s infrastructure. Developing FRTP rebar using the CFM addresses critical infrastructure challenges in the transportation sector, where reinforced concrete is the core material used in bridges, highways, and other transit systems. FRTP rebar could significantly extend the service life of transportation structures, reduce lifecycle maintenance costs, and address longevity challenges against environmental degradation.
