Flexural and Pseudo-Ductile Performance of Unidirectional and Bidirectional Carbon Fabric-Reinforced Mortar

This research aims to study the effect of introducing unidirectional (CFu) and bidirectional (CFb) carbon fabric into cement mortar (CM) on its flexural and pseudo-ductile performances. The experiments were performed on fabric/CM samples with a varying fabric distribution (single, double, and triple layers). The cohesion of fabrics in CM matrices and morphology of the damaged surfaces were examined using an optical microscope, while the flexural response was measured using a universal testing machine. The pseudo-ductile property, in the form of the ductility index (DI), was numerically modelled for CM matrices based on the measured flexural curves using different energy criteria models. Microstructure analysis showed a strong fabric cohesion in the matrices along with the production of more hydration products, which led to a transformation in the linear load-deformation relationship of mortar into the ideal shape of ductile material in the case of CFb/CM. In the case of the CFu/CM samples, two main drop points appeared with a long distance between them. In addition, the flexural load was significantly increased by introducing three layers of each type of fabric to CM, with an improvement of 75% (CFu/CM) and 68% (CFb/CM) compared to neat mortar. Similarly, the deformation till break was improved by 452% (CFu/CM) and 367% (CFb/CM). The DI analysis confirmed these results: the DI performance was improved by up to 140% by embedding. Based on these results, carbon fabric has high potential to enhance the strength and ductility of cementitious matrix.