Preparation and Acoustic Performance Optimization of Porous Sound-Absorbing Cement Materials Based on Recycled Cellulose Fiber

The development of multifunctional porous materials capable of efficiently attenuating wave propagation is of increasing importance for sustainable engineering applications. In this study, recycled cellulose fiber (RCF) was employed as a reinforcing phase to fabricate porous sound-absorbing cement-based composites through physical foaming and fiber modification techniques. An orthogonal experimental design was adopted to investigate the effects of RCF content, water-cement ratio, and foaming agent dosage on pore structure evolution and wave attenuation performance. Acoustic properties in the frequency range of 500–4000 Hz were evaluated using the impedance tube method, while scanning electron microscopy was applied to characterize the pore morphology and fiber-matrix interface. The results demonstrate that the incorporation of 2% RCF significantly enhances mechanical toughness and optimizes pore connectivity, increasing the flexural strength from 0.52 MPa to 0.92 MPa and the fracture energy from 18.3 N/m to 52.1 N/m. The optimized composite achieves a peak sound absorption coefficient of 0.89 at 2000 Hz while reducing carbon emissions by 48.6%–66.8% compared with conventional cement materials. The synergistic regulation of pore architecture and fiber reinforcement provides an effective mechanism for broadband wave energy dissipation and offers useful design insights for porous functional materials employed in acoustic engineering as well as electromagnetic wave absorption and propagation control applications.