Acoustic behavior of porous concrete. Characterization by experimental and inversion methods

Abstract

The use of porous concrete solutions with lightweight aggregates has become increasingly common in noise control due to their versatility in exterior and interior applications. In this work, samples of porous consolidated concrete with aggregates of expanded clay were produced, in order to study the influence of the grain size, thickness and water/aggregate/cement ratio on the sound absorption. Experimental techniques were used to obtain the surface impedance and sound absorption coefficient. In addition to experimental characterizations, an inverse method was used (based on a genetic algorithm) to obtain the macroscopic parameters capable of representing the materials studied through the theoretical model of Horoshenkov-Swift. Using the theoretical Horoshenkhov-Swift model it becomes possible to represent these materials in numerical models as equivalent fluids.

Performance of Low-Height Railway Noise Barriers with Porous Materials

“…Six samples of porous concrete were produced using expanded clay aggregates, with grain size of 0-2 mm. All samples were prepared with 10.1 cm of diameter and thickness of 4, 6 and 8 cm, being these procedure previously presented in [23]. The sample proportions in weight (kg) are presented in Table 1.…”

“…It was observed that the increase in the thickness produces a shift in the sound absorption coefficient curve towards low frequencies. (retrieved from [23]).…”

“…where α ana is the absorption coefficient obtained from the Horoshenkov and Swift model [33], and α exp is the experimental absorption coefficient. These four macroscopic parameters were previously obtained in [23], and are presented in Table 2. The open porosity was the only macroscopic parameter experimentally determined, using the water saturation method.…”

“…Carbajo et al [22] studied perforated concrete and highlighted the higher durability and the excellent strength-to-weight ratio of this solution. Pereira et al [23] studied the influence of the water-cement ratio, the expanded clay grain size, and the sample thickness in the sound absorption behaviour, while Zolanvari [24] studied the fluid-equivalent representation of porous concrete using different aggregates.…”

Acoustic-Based Screening Method for the Detection of Total Aflatoxin in Corn and Biological Detoxification in Bioethanol Production

“…The differences between the wholesome (less scabby nuts) and contaminated nuts (more scabby nuts) can also be detected by screening acoustic techniques ( Figure 5). Experiments have shown that the acoustic behavior of porous granular materials can be characterized essentially in terms of porosity and airflow resistance (Guo et al, 2019;Pereira et al, 2019). Furthermore, it was found (Guo et al, 2005) that in beads of cereal grains, the absorption of the acoustic signal depends on the size and shape of the particles.…”