Fiber effect on interfacial bond between concrete and fiber-reinforced mortar

Field overlay and bridge deck studies have suggested that vertical curling deflections and debonding can be reduced when the overlay contains fiber reinforcement. This study investigates the tensile and shear bond between aged concrete and fiber-reinforced mortar. Three macrofibers commonly used in fiber-reinforced concrete pavement overlays or bridge decks were investigated. The macrofibers were a stretched synthetic, a textured synthetic, and a hooked-end steel fiber. The tensile fracture energy within the fiber-reinforced mortar material and an interfacial tensile bond energy between the fiber-reinforced mortar cast against the aged and sandblasted concrete were all higher than that of plain unreinforced mortar. The peak loads associated with tensile or shear bond failure were not statistically affected with the addition of fibers in the overlay mixture. Overall, the interfacial tensile bond energy did improve as the fiber volume content increased, especially because some of the fracture path occurred through the mortar layer and was bridged by the fibers near the interface surface.