Mechanical Characteristics and Microstructure Analysis of Carbon Nanotube-Nanosilica-N66 Nanofiber-Reinforced Cementitious Composites

To overcome brittleness and improve the mechanical performance of cement composites, carbon nanotube-nanosilica-N66 nanofibers were developed in this study using electrospinning technology. To mitigate agglomeration and the limited bridging capability of conventional nanomaterials, carbon nanotubes were aligned within nylon 66 fibers and nanosilica was incorporated onto their surface. Cement pastes reinforced with the developed nanofibers showed substantial performance improvements, increasing tensile strength by 62%, compressive strength by 38%, and fracture toughness by 69% compared to the control group. Field emission scanning electron microscopy analysis visually confirmed the physical bridging and filling effects within the capillary voids. In addition, thermogravimetric, energy-dispersive spectroscopy, and X-ray diffraction analyses demonstrated a chemical pozzolanic reaction, in which the nanosilica on the fiber surface consumed excess calcium hydroxide to generate high-strength calcium silicate hydrate gels.