Recycling glass fiber reinforced polymer (GFRP) composite materials has been proven to be challenging due to their high mechanical performance and high resistance to harsh chemical and thermal conditions. This work discusses the efforts made in the past to mechanically process GFRP waste materials by cutting them into large-sized (cm scale) pieces, as opposed to pulverization, for use in concrete mixtures. These pieces can be classified into two main categories—coarse aggregate and discrete reinforcement, here referred to as “needles.” The results from all the studies show that using GFRP coarse aggregate leads to significant reductions in the compressive strength and tensile strength of concrete. However, GFRP needles lead to sizable increases in the energy absorption capacity of concrete. In addition, if the glass fibers are longitudinally aligned within the needles, these elements can substantially increase the tensile strength of concrete. Processing GFRP waste into needles requires less energy and time than that for producing GFRP coarse aggregate. Also, compared to pulverized GFRP waste, which consists of broken and separate particles of glass and resin that at best can be used as low-quality fillers, GFRP needles are high strength composite elements
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Shear behavior of reinforced concrete beams with GFRP needles as coarse aggregate partial replacement: Full-scale experiments
Fiber reinforced polymer (FRP) waste is becoming an environmental concern due to the widespread use and non-biodegradable nature of FRP composites. Cutting FRP waste into discrete reinforce-ments (referred to as “needles” hereafter) as coarse aggregate in concrete has been suggested as a possible solution to FRP waste recycling. It has previously been observed in small specimens that FRP needles increase the tensile strength and energy absorption capacity of concrete. This paper presents an experimental investiga-tion into the effect of GFRP needles as coarse aggregate partial replacement in concrete on shear behavior of full-scale reinforced concrete (RC) beams. A total of 10 RC beams without steel stirrups in the critical zone were tested under four-point bending. The volume replacement ratio of the coarse aggregate and the surface type of GFRP needles were chosen as the test parameters. GFRP needles, with either smooth or helically wrapped surfaces, were added to the concrete mix to replace 5% or 10% of coarse aggregate by volume, respectively. All test beams failed in shear in a brittle manner with the ductility being slightly enhanced by the partial replace-ment of coarse aggregate using GFRP needles. An enhancement of 8%-10% in the load carrying capacity was observed in beams with helically wrapped needles, while beams with smooth needles showed a reduction in the load carrying capacity.
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- Award ID(s):
- 1949818
- NSF-PAR ID:
- 10148556
- Date Published:
- Journal Name:
- Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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