The students are making beam plates with two types of E-glass reinforced thermoplastics – one based on Arkema’s EliumTM acrylic resins and one based on polyethylene terephthalate glycol (PETg) prepreg tapes supplied by PolyOne. After the plates are made, they are completely encased in concrete.
For the Elium-based plates, the students used vacuum-assisted resin transfer molding (VARTM) to create the base of the plate, as well as thermoplastic studs to transfer stress between the composite and the concrete. They then used a unique friction welding technique to bond the studs to the plate.
For the PETg prepreg tape-based plates, the students used Dieffenbacher’s signature Fiberforge RELAY®2000 machine, which uses an automated tape laying (ATL) system to produce tape lay-ups from continuous FRP composites that correspond closely to the final part. The students then transported the semi-finished part to an infrared oven where the material gets softened and later goes into a stamp forming press. This process allowed the students to generate both flat and corrugated plates. According to the researchers, a corrugated structure can increase the flexural stiffness and strength of the plate, which allows it to withstand dead loads before the concrete has cured.
Lopez-Anido says the process of determining the best way to make each plate was not easy and would not have been possible without ACMA’s UMaine liaison Madeline Wehrle, who played a key role in connecting the university to ACMA members with expertise to help the students make the best use of the thermoplastics.
“I don’t think we could have done this by ourselves,” says Lopez-Anido. “This is not just a project where you order materials, they arrive and then you make the product. You need to really work with the material suppliers, and you need come up with a process that really takes advantage of the material.”
The students have completed initial testing of the material properties and have sorted them into a database that will later be used for structural analysis. The next phase, Lopez-Anido says, will be to conduct shear tests of hybrid components.
“We’re basically building concrete blocks with thermoplastic composite panels that are attached with shear studs,” he says. “We’re looking at strength, and we’re looking at ductility of those shear studs.” After that, the plan is to test full beams made with the materials. Eventually, says Lopez-Anido, the unique combination of materials and processes could be used to make bridge decks, retaining walls and columns.