Enhanced Post-crack Load Carrying Capacity of Nano and Micro Scale Carbon Fiber Reinforced Mortars

Abstract

A thorough investigation of the pre-peak, first crack and post-crack flexural response, energy absorption performance and ductility of cement mortar composites with hybrid reinforcement using nano and micro scale carbon fibers took place in this study. Young’s modulus, energy absorption capability and energy based dimensionless indices (toughness indices) were investigated through the Linear Elastic Fracture Mechanics theory. Prismatic notched specimens of neat mortar and mortars reinforced with 0.1 vol.% CNFs and/or 0.5 vol.% CFs were subjected to a three-point close loop bending test, using the crack mouth opening displacement, CMOD. Combined networks of CNFs and CFs were incorporated in mortar matrix in order to investigate the synergistic effect of hybrid reinforcement on the mechanical properties of the single-reinforced mortars. The experimental results showed an exceptional multi scale mechanical performance of nano and micro scale fiber reinforced mortars as reflected from the load-CMOD response of specimens. The energy absorption capability and load carrying capacity of multiscale reinforced mortars after the formation of the initial crack (first crack), are outstandingly improved as indicated by the 138 and 100% increases of the proposed size independent toughness indices, up to the peak load and the ultimate failure, respectively.