Effect of recycled fiber modified by CNTs-epoxy resin composite coating on mechanical properties of mortar

In this study, the wastes GFRP was mechanically crushed and recycled GFRP fibers with a uniform aspect ratio were obtained through vibration screening and water separation treatment. In light of the surface-based interfacial defects present in recycled GFRP fibers, an epoxy resin-based nanocomposite coating reinforced with carbon nanotubes (CNTs) was employed for interfacial modification. The chemical properties of the recycled GFRP fibers before and after modification were characterised by XRD, FTIR and DTA. The changes in alkali resistance, mechanical properties and microstructure of the recycled fibers before and after modification were investigated by Alkali resistance test, mechanical testing and Scanning Electron Microscopy (SEM). Results indicated that the improvement of the coating on the fibers mainly included, blocking the erosion of alkali ions on the surface of the fibers and improving the mechanical properties of the fibers, reduced the shrinkage, and water absorption, with the highest compressive and flexural strength of 59.60 MPa and 7.13 MPa, respectively. The surface roughness due to the presence of resin and CNTs prevents easy debonding of fibers from the mortar. This property promotes strong bonding of fibers with the mortar matrix resulting in more effective fiber performance and improved mortar strength while enabling fiber recycling.