Determination of Vibroacoustic Parameters of Polyurethane Mats for Residential Building Purposes

This paper is aimed at investigating the use of polyurethane mats, usually used as ballast mats, for residential building purposes. Ballast mats have features that may improve the vibroacoustic comfort in residential rooms. Their strength is certainly an advantage, along with vibration and acoustic insulation. However, the problem that an engineer has to deal with, for example in modeling these types of mats, is a limited knowledge of the material’s vibroacoustic parameters. Knowledge of these may be useful for residential buildings. This paper presents measurements of the vibroacoustic parameters of polyurethane mats, together with a suitable methodology and some results and analysis. The two main material parameters responsible for vibroacoustic protection were measured: the dynamic stiffness, which is related to the acoustic properties of the material, and the critical damping coefficient, which is obviously responsible for damping. The measurement methodology is clearly described. A total of five polyurethane materials with different densities were tested. It was possible to identify a relationship between the material density and the vibroacoustic parameters, which could offer an indication of which material to use, depending on the stimulus affecting a human in a given location.

Natural Fibre Insulation Materials: Use of Textile and Agri-food Waste in a Circular Economy Perspective

Fibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.

3D Modelling of Hydric Transfers in Spruce Wood with Consideration of Sorption Hysteresis

Buildings are responsible for a large portion of the total energy consumption, and have a heavy environmental impact. Wood is one of the most used bio-based building materials, as it helps reducing the environmental footprint of the construction sector. Spruce wood is widely available in France and therefore massively used in buildings. It has interesting thermal and acoustic insulation performances and a good hydric regulation property. Spruce wood microstructure is highly heterogeneous and multiphasic, which makes it harder to apprehend. On the other hand, sorption hysteresis phenomenon is responsible for the moisture accumulation in porous building materials. It is often neglected in hygrothermal transfers modelling, which leads to incorrect water content values. The aim of this work is to investigate the influence of the sorption hysteresis phenomenon on the hydric transfers of spruce wood. The heterogeneity of the microstructure is also considered through 3D tomographic reconstructions included in the modelling.

Fabrication of cellulose-based aerogel for thermal and acoustic insulation applications

A method to prepare aerogels from rice straw and polyvinyl alcohol in the presence of fiberglass and glutaraldehyde is herein reported. The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The obtained aerogels should be considered as a promising material for upcoming applications, since it has high porosity (up to 93.72%), low density (0.083-0.127 g/cm3), super low thermal conductivity (0.032-0.048 W/mK), high Young modulus (0.201-1.207 MPa), high sound absorption (absorption coefficient of 0.87) and a good oil adsorption capacity (4.8 g/g).

Perforated Steel Stud to Improve the Acoustic Insulation of Drywall Partitions

Steel studs are an inevitable part of drywall construction as they are lightweight and offer the required structural stability. However, the studs act as sound bridges between the plasterboards, reducing the overall sound insulation of the wall. Overcoming this often calls for wider cavity walls and complex stud decoupling fixtures that increase the installation cost while reducing the floor area. As an alternative approach, this research reveals the potential of perforated studs to improve the acoustic insulation of drywall partitions. The acoustic and structural performance is characterized using a validated finite element model that acted as a prediction tool in reducing the number of physical tests required. The results established that an acoustic numerical model featuring fluid-structure-interaction can predict the weighted sound reduction index of a stud wall assembly at an accuracy of ±1 dB. The model was used to analyze six perforated stud designs and found them to outperform the sound insulation of non-perforated drywall partitions by reducing the sound bridging. Overall, the best performing perforated stud design was found to offer improvements in acoustic insulation of up to 4 dB, while being structurally compliant.

A Century of Use of SOLOMIT Thermal Insulation Panels

This article traces the century-old history of using a thermal and acoustic insulation panel called SOLOMIT. It presents some of Sergei Nicolajewitsch Tchayeff’s patents, on the basis of which production and installation took place. The survey section provides examples of the use of this building component in Australia, Czechoslovakia, France, Germany, the Netherlands, Poland, Russia, the Soviet Union and Spain. It pays attention to applications in the 1950s and 1960s in collectivized agriculture in Czechoslovakia. It also presents the results of measuring the thermal conductivity of a panel sample, which was obtained during the reconstruction of a cottage built in the 1950s and 1960s of the 20th century. Even today, SOLOMIT finds its application all over the world, mainly due to its thermal insulation and acoustic properties and other features, such as low maintenance requirements, attractive appearance and structure and cost-effectiveness.

Acoustics of a School Building Made in Wooden Technology on the Example of Building from the Second Half of the 19th Century

The Władysław Matlakowski School in Zakopane was established in 1877. After the war damage, during the Communist rule in Poland the school was rebuilt and renovated. As a result, the original character of the classrooms was distorted. Fiberboards used for interior finishing changed the acoustic climate of the rooms. The reverberation time of the tested rooms considerably exceeds 2 seconds for low frequencies and is below 2 seconds for medium frequencies. Thus, the reverberation conditions do not differ from typical school classrooms in Poland. The tests of reverberation conditions were supplemented by the measurements of acoustic insulation of partitions separating the chool classrooms from each other and from the corridor. The studies allow to infer that the noise possibly comes from the corridors or adjacent rooms.

Al-Based Foams as Permanent Cores in Al Castings: Effect of Surface Skin Thickness and Composition on Infiltration and Core-Shell Bonding

An emerging and still poorly explored application of aluminum foams is their potential use as permanent cores (inserts) in the casting of aluminum alloys. In this context, Al-based foams can introduce a weight reduction, the obtainment of cavities, a strength increase, the ability to absorb impact energy and vibration, acoustic insulation ability, the possibility to simplify the technological processes (no removal/recycling of traditional sand cores), and finally, they can be fully recyclable. Cymat-type Al foams with thin outer skin were used as permanent cores in Al-alloy gravity casting in the present research. Al-foams were characterized in terms of porosity, density, cell wall and skin thickness, surface chemical composition and morphology, and compression resistance. Cast objects with foam inserts were characterized by means of optical microscopy. The preservation of up to 50% of the initial porosity was observed for foam inserts with higher density. Metallurgical bonding between the foam core and the cast metal was observed in some regions.