2025-04-242025-04-242025Ruiz Martínez, J.D., Ríos Jiménez, J.D., Pérez-Soriano, E.M., Cifuentes-Bulté, H. y Leiva Fernández, C. (2025). Efect of nano silicon nitride on the microstructural characteristics and mechanical properties of ultra‑high‑performance steel fber reinforced concrete. Materials and Structures, 58 (103), 1-22. https://doi.org/10.1617/s11527-025-02634-9.1359-59971871-6873https://hdl.handle.net/11441/172065© The Author(s) 2025This study investigates the incorporation of an innovative nano-reinforcement, nano silicon nitride (NSIN), to enhance the workability and mechanical performance of ultra-high-performance fber reinforced concrete. The addition of NSIN at dosages of 0.25, 0.5, 0.75, and 1.5 wt% of cement was analyzed to evaluate its impact on the distribution and interaction between steel fbers and the cementitious matrix. Experimental analyses, including thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), were conducted to establish a relationship between the microstructural modifcations, fber-matrix interactions, and the resulting mechanical behavior. The fndings revealed that NSIN increased workability and extended setting time, enabling improved steel fber dispersion and interactionapplication/pdf22 p.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Ultra-high-performance concrete · Steel fber-reinforced concrete · Nano silicon nitride · Fracture · Fiber-matrix interactioninfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccesshttps://doi.org/10.1617/s11527-025-02634-9