Acoustical Characterization and Modeling of Sustainable Posidonia Fibers

Abstract

This article presents the results of an acoustic characterization of fibers obtained from Posidonia Balls (scientific name: Aegagropiles), produced by a marine plant (Posidonia oceanica) that is widespread in the Mediterranean Sea and can be found on beaches in large quantities, particularly following storm surges. The aim of this research is to evaluate the possible use of these fibers as eco-sustainable sound-absorbing materials and to define an acoustic model for the optimization of sound-absorbing panels made from these fibers. Experimental tests were conducted to measure airflow resistivity and sound absorption for different densities of loose fiber samples. From these experimental tests, the five physical parameters of the Johnson-Champoux-Allard model were calculated to obtain an analytical formulation of the acoustic behavior of the fibers depending on their density. To the author’s knowledge, this is the first time that an article has been published on acoustic data relating to the sound-absorbing performance of loose Posidonia oceanica fibers and that an analytical model has been presented that allows for the acoustical design of panels of different thicknesses and densities made with this material. An interesting aspect of this material is that the lignin fibers are ready for acoustic application due to the natural cleaning process of the waves and salt water. Furthermore, the methodology consists of a hybrid method between the experimental characterization of some parameters (i.e., different densities) and the numerical inversion of the acoustic data for other parameters. This is an effective solution that has rarely been adopted in other studies on sustainable materials.

Thermo-Acoustic Building Insulation Materials Fabricated with Recycled Fibers – Jute, Wool and Loofah

“…These results are due to the final fibers dimensions and the chosen mixing ratio which allowed to obtain very light panels with a density close to 20 kg/m 3 . It is therefore not surprising that even the thermal conductivity values are in line with panels made with wool and similar percentages of polyester, indicating a similar fibrous structure for the different samples [39]. As regards the use of clay, it is possible to note how it always leads to a worsening of the thermal insulation properties, induced by the greater density of the final product.…”

“…The innovative and recycled applications of different natural fibers in various forms in the C&B sector can be found in the literature, it is enough to mention flex [22], banana [25], coconut coir [26], [27], sisal [28], date palm [29], hemp [30], sheep wool [31], [32], jute [33] [34], oil palm [35], straw [36], wood-wool [37], kenaf [38] or posidonia [39]. While the use and application of wool fiber (from animal origin) mainly can be found as thermo-acoustic insulation material [39], [41], other experiments were conducted using them in cement matrix materials (mortar or plaster) [31],42], concrete composite [43] and reinforce concrete and carbon fiber precursor [44]. From the environmental impact point of view, the strategic importance of subsidies provided by local governments to incentivize waste prevention and reduce waste end-treatment should be underlined.…”

“…JF is recyclable and biodegradable. Moreover, energy consumption needed for its (and sub-products) production process is comparatively very low with respect to other fibers [39], [47]. JF's proven insulating property as well as its mechanical and physical strength, brings wider attraction to develop more sustainable building materials.…”

Study on adjustable low-frequency sound absorbers based on digital shunt loudspeakers

“…At present, conventional sound absorption technologies such as porous materials and resonant sound absorption structures exhibit excellent high-frequency sound absorption capabilities, but low-frequency applications are less effective. Increases in material thickness or depth of the back cavity are commonly used to enhance sound absorption coefficient at low frequencies [1][2] . It is urgent to study an excellent low-frequency sound absorber with compact dimensions, good stability, and easy adjustability.…”