Macroscopic-microscopic performance experiments of ceramic fiber modified cementitious grouting materials and study on the interaction mechanism between slurry particles

To improve the utilization of waste ceramic fiber particles, alleviate their environmental impact, and expand their application in grouting engineering, this study systematically investigated the effects of ceramic fiber content and size on the rheological properties, mechanical strength, and microstructures of cementitious slurries using a combined approach of macroscopic experiments and molecular dynamics simulations. The results show that ceramic fibers with a large specific surface area and high aspect ratio reduce slurry fluidity and increase viscosity by enhancing interparticle electrostatic adsorption, as verified by Zeta potential measurements. Despite the rheological tradeoff, the optimized incorporation of ceramic fibers densifies the matrix and improves toughness through lateral tensile stress; specifically, compared to the control group, the compressive strength of the 2.0 wt.% maximum aspect ratio ceramic fiber group increased by 84.3%. Microscopic characterizations reveal that ceramic fibers accelerate hydration, form a three-dimensional network, and bridge microcracks, although excessive fiber length causes entanglement, leading to poor flowability and stress concentration. Molecular dynamics simulations further confirm the strong adsorption between ceramic fibers and C-S-H gel, where longer fibers with larger specific surface areas yield higher interfacial energy and more stable interfaces, providing a microscopic mechanism for the macroscopic performance enhancement.