Fiber-Reinforced Facing Boards Based on Magnesium Binder

The influence of polypropylene fiber reinforcement of different lengths on the physical and mechanical properties of magnesia-based facing boards was investigated, and the interfacial bond strength between the fibers and the magnesium cement matrix was determined. The physical and mechanical properties and microstructure of the developed composites were characterized using standard testing methods: scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and numerical simulations performed in the ANSYS 2024 R1 software environment. The results showed that the highest flexural strength was achieved with the incorporation of 6 mm polypropylene fibers at a volumetric content of 1.5–2.0%. Under these conditions, the interfacial bond strength reached 1.29 MPa, while the strengthening coefficient increased by a factor of 4.35. For composites prepared using a mechanomagnetically activated binder, the bond strength increased to 1.81 MPa and the strengthening coefficient increased by a factor of 5.34. These findings demonstrate that polypropylene fiber reinforcement is an effective approach for improving the physical and mechanical performance of magnesia-based composites. Moreover, mechanomagnetic activation of the binder for 3 min, corresponding to the maximum isobaric–isothermal potential, contributes to the formation of a denser magnesia stone structure, leading to reduced crystallite size and increased dislocation density.