The role of interface in improving fracture toughness of shaped steel fiber

Mechanical properties of composite materials and their final performance are strongly influenced by the structure and properties of the fiber–matrix interface. A balance between sufficient load transfer and fiber pullout properties helps improve the performance of the composite materials. In this research, we employed sulfuric acid treatment to enhance fiber pullout and debonding through decreasing the fiber–matrix interlock. Atomic force microscope and scanning electron microscopy were employed to investigate the surface morphology of both treated and untreated steel fibers. Our results indicate that surface treatment improves the fiber roughness and therefore hinders brittle failures of the epoxy fiber-reinforced composite materials