Experimental Investigation of the Mechanical, Physical, and Microstructural Performance of Cement Boards Reinforced with Hybrid and PVA Fibers

This study explores the combined influence of hybrid fibers (HF) and polyvinyl alcohol (PVA) fibers on the structural and physical performance of fumed-silica cement boards. Scanning electron microscopy (SEM) was employed to analyze mortar mixtures containing different fiber proportions and to assess improvements in their microstructure. The experimental program included tests for compressive strength, stiffness, density, ultrasonic pulse velocity, and setting time. Findings show that incorporating 1% hybrid fibers yields the best mechanical performance, achieving a compressive strength of 46.89 MPa and a stiffness of 99.34, along with a 2.16% reduction in density compared to the reference mix. A mixture with 2% PVA fibers also enhances compressive strength (43.4 MPa) and stiffness, while higher fiber content generally leads to longer setting times. SEM observations revealed effective crack-bridging and thickening of the base matrix. Overall, the results indicate that the combination of 1% HF fibers and 2% PVA fibers represents the optimal formulation in terms of strength, durability, and rigidity, supporting the development of more advanced and high-performance cement boards.