Three-dimensional braided composites as innovative smart structural reinforcements

This study is a systematic effort focused on the development of feasible self-sensing braided composite rods (BCRs) for structural reinforcement and damage monitoring. In this route, BCRs were produced and reinforced with different carbon-based conductive fillers, including hybrid carbon nanotubes (CNTs)/graphene nanoplatelets (GNPs), chopped carbon fibres (CCFs), and directed (unidirectional) carbon fibres (DCFs) using a specific process. The mechanical and self-sensing performances of the BCRs were evaluated using various tests. Furthermore, a honeycomb 3D system of DCF/BCRs was used to reinforce a 100 mm × 100 mm × 850 mm concrete beam, and the piezoresistivity of the specimen was investigated under cyclic flexural loading with different patterns. The maximum tensile strength and elastic modulus were observed for the BCR reinforced with 1.0% (wt) CCFs. However, the maximum sensitivity was attained for the BCRs with 3.0% hybrid CNTs/GNPs. The analysis of the results and economic assessment showed that DCF-reinforced BCRs are the optimum choice for developing a feasible, reliable, and economic structural health monitoring technique.