Improved Post-crack Energy Absorption Capability of Cementitious Composites Reinforced with CNTs and PPs

Abstract

In this study a thorough investigation of the pre-peak and post-crack mechanical behavior of cement mortars reinforced with carbon nanotubes and polypropylene microfibers, took place. Flexural strength, Young’s modulus, energy absorption capability and energy based dimensionless indices (toughness indices) were investigated. Prismatic specimens of neat mortar and mortars reinforced with 0.1 vol.% CNTs and 1.0 vol.% PPs were subjected to a three point close loop bending test. Combined networks of CNTs and PPs also incorporated in mortar matrix in order to investigate the synergistic effect of hybrid reinforcement on the mechanical properties of mortar composites in comparison to the singly-reinforced mortars. The experimental results showed an exceptional multi scale mechanical behavior of mortars as reflected from the load-deflection curves. Cement-based composites using carbon nanotubes or ladder scale reinforcement of CNTs and PPs are characterized by 1.9 times higher flexural strength and stiffness and 50% increased flexural toughness over the mortars reinforced with micro scale fibers alone. The post-crack energy absorption capability of multiscale reinforced mortars after the formation of the “first crack”, is also outstandingly improved as indicated by the increases of the toughness indices I₅, I₁₀, I₂₀.