Objectives: Problem definition and objectives: One of the important challenges in improving the quality of gypsum panels is to improve their acoustic properties by lightening them, such as using waste paper fibers, and optimizing the sound absorption and transmission loss of these types of lightened panels can be evaluated. In this study, the acoustic performance of gypsum board panels reinforced with recycled writing waste paper fibers and enhanced with selected polymer additives was investigated. The main aim was to improve sound absorption and sound insulation in these panels.
Methodology: For this purpose, three types of samples were prepared: gypsum board, fiber-reinforced gypsum board (gypsum fiberboard), and fiber-reinforced gypsum board with additives such as polyvinyl alcohol, modified hydrated lime, and cement (polymeric gypsum fiberboard). Sound absorption tests were conducted according to ISO 10534-2 and ASTM E1050 standards using the transfer function method and impedance tube to measure the sound absorption coefficient. Sound insulation was tested based on ASTM E2611-09 to measure the sound transmission loss index. To cover the full frequency spectrum in acoustic testing, 10 cm diameter samples were used for low-frequency ranges (63–500 Hz), and 3 cm diameter samples for higher frequency ranges (630–6300 Hz).
Results: The sound absorption results showed that the polymeric gypsum fiberboard had the best performance up to 4000 Hz compared to the other panels. The fiber-reinforced gypsum panel also outperformed the gypsum board. Both gypsum fiberboard types were slightly better than gypsum board and were classified in the low sound absorption category (Grade E). However, all three samples showed poor performance in low frequencies (around 250 Hz) and mid-range frequencies (500–1000 Hz), while they performed better at high frequencies (2000–4000 Hz), particularly the polymer or fiber-reinforced panels. The highest sound absorption coefficient was achieved by the polymeric gypsum fiberboard, reaching approximately 0.58 at 3150 Hz, followed by the gypsum fiberboard (0.46 at 4000 Hz) and gypsum board (0.44 at 4000 Hz). The matrix formed by the combination of additives, gypsum, and fibers in the polymeric gypsum fiberboard created porosity, improving sound absorption. In terms of sound transmission loss index, both the gypsum fiberboard and polymeric gypsum fiberboard performed better at base frequencies compared to the gypsum board. Interestingly, the gypsum fiberboard outperformed the polymeric gypsum fiberboard in sound insulation. The sound transmission loss index of the polymeric gypsum fiberbard up to 4000 Hz was lower than the gypsum fiberboard but higher than the gypsum board, with sound transmission reduction reaching up to 28 dB. The sound transmission loss index response of the gypsum board peaked at approximately 33 dB in the 4000–6000 Hz range. The gypsum fiberboard exhibited a more uniform sound transmission loss across all frequency ranges, providing sound insulation up to approximately 37 dB. The polymeric gypsum fiberboard showed moderate performance compared to the other two types.
Conclusion: Generally, all samples demonstrated weak performance below 1000 Hz, with sound insulation below 10 dB, while their best performance was in the mid-frequency range (2000–6000 Hz). Their effectiveness declined above 6000 Hz. Sound insulation graphs indicated that both the gypsum fiberboard and polymeric gypsum fiberboard had a positive effect on the sound transmission loss index. According to the Noise preference measurement charts (based on standard 8834-1) for indoor noise measurement, the gypsum board was rated at 15, while the gypsum fiberboard and polymeric gypsum fiberboard were rated at 20. The porous texture of the polymeric gypsum fiberboard enhanced sound absorption, and the flexible structure of the fiber-reinforced gypsum panel contributed to improved sound insulation. Thus, gypsum fiberboard or polymeric gypsum fiberbard, along with layers of other materials, has the potential for acoustic applications. Gypsum boards reinforced with fibers and polymer additives are used in the production of lightweight, durable, fast-setting, and environmentally friendly building materials and are mainly used in partition walls, false ceilings, wall coverings, and high-rise construction projects.