To improve the impact sound insulation performance of building floors and meet the objective requirements for living comfort of residents, in this article, three kinds of elastic cushion materials, Portuguese cork board, BGL insulation sound insulation foam board, and EPP polypropylene plastic foam board, are applied to the sound insulation of a light frame wood floor structure of the same bedroom and compared to the ordinary floor. This study uses the transfer function method and transient excitation method to measure the sound insulation, damping ratio, and elastic modulus of materials, as well as the sound insulation of the floor under the jumping excitation method of daily behavior. Through comparative analysis, the results and factors of improving the sound insulation performance of the floor are obtained, according to which three types of elastic cushion materials and the floor covering composed of them have higher vibration and noise reduction performance. Among them, the overall sound insulation performance of BGL board floor is the highest, followed by EPP board and cork board floor, and ordinary OSB floor is the lowest. Under the jumping excitation method, three floating floors can improve the impact sound insulation performance of the middle and low-frequency bands.
The optimal design of floor sound insulation for light wood frame structures is the key to ensuring the comfort of the upper and lower floors of the building, as well as an important factor for measuring the healthy lifestyle of residents and ensuring the quality of life. In terms of experimental research on building floor materials and structures, foreign experts and scholars have made abundant research on floor sound insulation [
For this reason, according to ISO 10534-2 and ISO 140-7, this article intends to apply elastic cushion materials from Portuguese cork board, BGL board, EPP board, in the design of three types of sound insulation of the floor structures in the same bedroom of a light wood frame construction. And the sound insulation performance of the ordinary OSB floor covering is compared. By carrying out dynamic tests on the damping ratio and elastic modulus parameters of related materials, as well as the sound insulation test and analysis of the floor under the jumping excitation method of daily behavior, it is possible to promote the application of new elastic cushion materials in the timber structure industry. It is expected that this study will provide a reference for improving the optimization design and application of the sound insulation structure of the light frame wood floor systems.
Material | Dimension/mm | Density/kg·m-3 | Moisture content/% | Number of specimens/Pieces | |
---|---|---|---|---|---|
Mid-low frequency | High frequency | ||||
Cork board | Φ100 × 10 | Φ30 × 10 | 158.50 | – | 5 |
Φ100 × 20 | Φ30 × 20 | 5 | |||
Φ100 × 30 | Φ30 × 30 | 5 | |||
Φ100 × 40 | Φ30 × 40 | 5 | |||
Φ100 × 50 | Φ30 × 50 | 5 | |||
BGL board | Φ100 × 20 | Φ30 × 20 | 22.53 | – | 5 |
EPP board | Φ100 × 20 | Φ30 × 20 | 15.60 | – | 5 |
OSB board | Φ100 × 15 | Φ30 × 15 | 604.50 | 16.0 | 5 |
Three elastic cushion materials used in the structure of the floor and OSB material are taken as test specimens with a diameter of 100 mm for the mid-low frequency (below 1600 Hz) range; the specimens with a diameter of 30 mm are used for the high frequency (1600–6300 Hz) range. Basic parameters of the specimens are shown in
Specifications of the structural material specimens are shown in
Material | Dimension/mm | Density/kg·m-3 | Moisture content/% | Test numbers/Pieces |
---|---|---|---|---|
Wooden floor | 610 × 82 × 18 | 664.29 | 15.8 | 5 |
Cork board | 500 × 100 × 10 | 158.50 | – | 5 |
500 × 100 × 20 | 5 | |||
500 × 100 × 40 | 5 | |||
500 × 100 × 50 | 5 | |||
BGL board | 600 × 120 × 20 | 22.53 | – | 5 |
EPP board | 500 × 100 × 20 | 15.60 | – | 5 |
OSB floor panel | 500 × 100 × 15 | 604.50 | 16.0 | 5 |
Pine panel | 800 × 88 × 8 | 502.49 | 15.4 | 5 |
The object of this research is a two-story light wood frame construction with a 9 m2 bedroom on the second floor. The four types of floor structures include one type of ordinary floor and three types of a floating floor. The three types of floating floor are constructed by adding three different elastic cushions between the floor slab and the floor covering. They are cork board floating floor, BGL board floating floor, and EPP board floating floor. The floor structure is shown in
BSWA SW422 510045 impedance tube. The large and small pipe diameters 100 mm and 30 mm, which are used for medium and low-frequency and high-frequency tests, respectively. Supporting equipment include sound level channel calibrator, digital-to-analog converter, BSWA TECH power amplifier, BSWA TECH signal generator, signal receiver, and VA-Lab test and analysis system; DYM3 barometer, indoor thermometer, and hygrometer; CRAS vibration and dynamic signal acquisition and analysis system; CA YD-125 piezoelectric acceleration sensor; TES1350B sound level meter; AWA6221A sound level calibrator; HK 30 wood moisture tester; TG328B electro-optical analytical balance (0.1 g); bench vise; rubber hammer; steel tape measure (0–5 m); vernier caliper (0–150 mm).
The test was carried out in the laboratory. According to ISO 10534-2, the four-microphone method based on transfer function theory is used to measure the sound insulation of cork board, BGL board, EPP board, and OSB board [
The main test steps: The instrument was connected and the specimen was placed according to
The test was carried out in the laboratory. The transient excitation method was used to test the damping ratio and elastic modulus of cork boards, BGL boards, EPP boards, and OSB boards. The main test principle: the free beam specimen was hit with a hammer to obtain its time-domain spectrum and frequency spectrum. Then the calculation of the logarithmic reduction coefficient
where, ρ – the air-dry density of the test material, in kg·m-3; l–the length of the test material, in mm; h–the thickness of the test material, in mm.
The main test steps: According to
The test was carried out in the field situations. Jumping is one of the most common activities in life. And the adult jumping is classified as a heavyweight shock source. For this reason, the transient excitation method was used to measure the impact sound insulation of four types of floor slabs in the jumping mode under the condition of closed doors and windows and to study their impact sound insulation characteristics. The flowchart of the test is shown in
In the actual measurement, the expression of weighted average impact sound pressure level L in the room under test is:
The expression of impact sound improvement ΔL is:
The main test steps: First, 9 fixed measuring points of the sound level meter were installed; An adult (man, 175 cm and 70 kg) performed jumps on the floor according to the fixed-point jump excitation method, the jump height was 150 ± 10 mm (
The sound insulation curves of the four material plate specimens are shown in
The sound insulation effect of a cork board with thickness of 20 mm is better within the frequency of 500–1000 Hz. However, when the frequency exceeds 1000 Hz, the sound insulation effect is achieved with a cork board of 30 mm thick. This is because sound waves are transmitted inside the material and resonate, causing the sound insulation curve of the material to appear low in sound insulation. BGL board and EPP board are both extruded foamed materials. At 1000 Hz and 1200 Hz, foam boards have obvious sound insulation troughs respectively. Due to a large number of bubble structures in the foam material, the sound wave resonates in its internal transmission, causing the material to locally reduce the sound insulation. When the frequency is less than 1000 Hz, the sound insulation performance of two sound insulation panels gradually decreases as the frequency increases. BGL board has high sound insulation characteristics within 2000–3000 Hz, while the sound insulation performance of the EPP board decreases with the increase of frequency within 1000–4000 Hz. In the high-frequency range, the sound insulation performance of two materials is relatively low. OSB board has few internal pores and high density, and its airborne sound insulation performance is relatively stable in the middle and high-frequency range.
The dynamic test of the damping ratio ξ of the flexible cushion material of the light frame wood floating floor considering cork board, BGL board, and EPP board is carried out by the transient excitation method. The average damping ratio ξ of the elastic cushion material is shown in
Material | Thickness/mm | Average damping ratio ¯ξ/% | Coefficient of variation CV/% |
---|---|---|---|
Cork board | 10 | 8.37 | 7.46 |
20 | 8.83 | 9.38 | |
40 | 8.84 | 3.87 | |
50 | 10.38 | 16.18 | |
BGL board | 20 | 4.57 | 6.81 |
EPP board | 20 | 5.80 | 8.54 |
The energy consumption mechanism of BGL board and EPP board is as follows: When subjected to vibration, the foam board itself produces large deformation to consume impact energy. The vibration wave forms reflection and refraction on the bubble wall and cavity structure inside the material, continuously consuming energy, and its transmission energy attenuation effect is good. Because the wave structure at the bottom of the BGL board can effectively improve its overall vibration reduction, the BGL board has the greatest flexibility. When the cork board is subjected to an external seismic source, its deformation is relatively small, and its energy consumption is mainly through its internal cavity structure and internal friction. As the surface structure of the floor, the solid wood floor is in direct contact with the impact noise source. Because of its high elastic modulus, the vibration reduction effect is relatively small. However, considering the actual stress of the floor structure, the solid wood floor can effectively ensure the overall stiffness of the floor structure.
Under the condition of closed doors and windows, the improvement ΔL of the impact sound of BGL, EPP, cork board, and ordinary OSB floor covers measured by the transient excitation method are 22.2, 20.3, 15.9, and 12.6 dB, respectively. Obviously, this is because the cork board, BGL board, and EPP board all have a higher damping ratio and smaller elastic modulus value to achieve the vibration and sound insulation effect.
As a kind of instantaneous motivation, jumping is one of the most common activities in life. Under the condition of closed doors and windows the measured frequency spectrum of the BGL and EPP floor structures selected in the article is shown in
In
In this experiment, only one adult male participated in the experiment, and certain training was given to him in the early stage of the experiment to ensure that the jumping height was maintained at 150 ± 10 cm, and the soles of the feet should land as much as possible. The experimental data was screened, but the results have certain errors and limitations. In the future, more people of different heights and weights will need to be involved in order to explore the impact of different heights and weights on the experimental results, and make the experiment more perfect. The data is more comprehensive and the conclusion is more precise.
Among the materials tested in this research, the damping ratio of the cork board is the highest, followed by the EPP board, and the BGL board, and the damping ratio of the OSB is the lowest. In the terms of the elastic modulus of the tested materials, OSB has the highest values, followed by cork boards, EPP, and BGL board has the lowest. Three elastic cushion materials of BGL, EPP, and cork board have strong vibration and sound insulation performance. Therefore, under the jump excitation mode, the measured impact sound insulation of three types of floating floors, considering BGL, EPP, and cork board, is 3–10 dB higher than the sound insulation of ordinary OSB floors, and the impact sound pressure is 1.97–8.61 times higher than the ordinary OSB floor respectively. This can effectively improve the sound pressure ratio of the indoor space of the building. The overall sound insulation performance of BGL floors is the highest, followed by EPP and cork floors, and ordinary OSB floors are the lowest. On the other hand, under the jump excitation mode, due to the concentration of the instantaneous impact energy of people on the floor structure, the sound pressure of the impact excitation is large in the high-frequency range, and the sound effect is more obvious. Three types of floating floor coverings, considering BGL, EPP, and cork board, can effectively improve the impact sound insulation performance of the structure in the middle and low-frequency bands and can improve the user’s living comfort conditions.