Benefits of Short Kevlar Fiber Reinforcement at the Interface for Repair of Concrete-Like Materials

Abstract

Interfacial adhesive bonding of concrete-like materials is strengthened by short Kevlar fibers. The tough and flexible Kevlar fibers, bridging across grain structures, can effectively suppress premature surface and subsurface local fracture at the interface during the formation of fictitious crack. The adhesive joint, formed through either repairing of a gap using epoxy or structural reinforcement using carbon-fibers/epoxy composite, is changed into a composite adhesive joint because of use of Kevlar fibers at the interface. In this study, grey granite samples were tested under three-point-bending with two different interfacial repair conditions: (1) epoxy only, and (2) epoxy with short Kevlar fibers of 6 mm in length. Peak loads and RILEM fracture energy Gf were measured from as-received granite samples, and the two different types of repaired samples. Improvements were observed in both the peak load and fracture energy. Formation of fictitious crack and its influence on the peak load were discussed.