Acoustic damping building material

Abstract

An acoustic damping building material (100) comprising an acoustic damping layer (118) secured to at least a portion of a substrate (110). The acoustic damping layer comprises at least two media wherein the at least two media are configured such that the acoustic damping layer comprises at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer to the substrate.

Claims

1. An acoustic damping building material comprising; a substrate and an acoustic damping layer, the acoustic damping layer being secured to a face of the substrate, at least a portion of the face being uncovered by the acoustic damping layer, the acoustic damping layer comprising at least two media, wherein a first media of the at least two media has a surface area defining a generally irregularly shaped particle, wherein the media are interspersed in a manner such that some of the irregularly shaped particles of the first media are in direct contact with adjacent irregularly shaped particles of the same media, and some other of the irregularly shaped particles of the first media are isolated from and do not contact other irregularly shaped particles of the same media, wherein the at least two media are configured such that the acoustic damping layer comprises at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer to the substrate, the direct energy transmission pathway comprising two contiguous irregularly shaped particles of the first media, the indirect energy transmission pathway comprising an irregularly shaped particle of the first media and a second media, said second media having a different transmission coefficient to that of the first media.

2. An acoustic damping building material as claimed in claim 1, wherein one of the at least two media comprises at least one polymeric material.

3. An acoustic damping building material as claimed in claim 2, wherein the at least one polymeric material comprises a polymeric particulate material or a polymeric granular material.

4. An acoustic damping building material as claimed in claim 3, wherein one of the at least two media comprises one or more further polymeric materials, a portion of the particles or granules of the polymeric material of one of the at least two media are contiguous to either an adjacent particle of a particle or granule of one or more further polymeric materials or the other of the at least two media so as to form an indirect energy transmission pathway through the acoustic damping layer.

5. An acoustic damping building material as claimed in claim 2, wherein the polymeric material is selected from the group consisting of natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, ethylene propylene diene monomer rubbers, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, and copolymers.

6. An acoustic damping building material as claimed in claim 1, wherein the other of the at least two media comprises a void volume.

7. An acoustic damping building material as claimed in claim 6, wherein the void volume is occupied by a fluid.

8. An acoustic damping building material as claimed in claim 1, wherein the acoustic damping material further comprises a polymeric binder, selected from the group consisting of emulsion polymers, polymer solutions, polymer dispersions, thermosetting polymers, and thermoplastic polymers.

9. An acoustic damping building material as claimed in claim 1, wherein one of the at least two media comprises between 5% and 80%2% of the acoustic damping layer.

10. An acoustic damping building material as claimed in claim 1, wherein one of the at least two media comprises between 10% and 50%2% by volume of the acoustic damping layer.

11. An acoustic damping building material as claimed in claim 1, wherein one of the at least two media comprises between 15% and 35%2% by volume by volume of the acoustic damping layer.

12. An acoustic damping building material as claimed in claim 1, wherein the substrate comprises a first face, a second face and an intermediate portion positioned between the first and second faces and an edge portion surrounding the intermediate portion such that the substrate, intermediate portion and edge member together form a panel or sheet of predetermined thickness.

13. An acoustic damping building material as claimed in claim 12, wherein the predetermined thickness of the substrate panel or sheet is between approximately 15 mm and approximately 50 mm.

14. An acoustic damping building material as claimed in claim 12, wherein the acoustic damping layer is secured to at least a portion of the first face of the substrate.

15. An acoustic damping building material as claimed in claim 12, wherein the acoustic damping layer is secured to at least a portion of the first face and at least a portion of the second face of the substrate.

16. An acoustic damping building material as claimed in claim 1, wherein the substrate comprises a material having a density between 900 and 1800 kg/m.sup.3.

17. An acoustic damping building material as claimed in claim 1, wherein the substrate comprises a cementitious bound material.

18. An acoustic damping building material as claimed in claim 17, wherein the cementitious bound material comprises a fibre cement panel or a fibre cement sheet.

19. An acoustic damping building system comprising: a building subframe structure, at least one section of an acoustic damping building material according to claim 1, the at least one section of acoustic damping building material being securable to the building subframe structure, and an aesthetic surface layer securable to the at least one acoustic damping building material, for providing an aesthetic building finish.

Description

(1) In the drawings,

(2) FIG. 1A is a perspective view of an acoustic flooring system according to the invention;

(3) FIG. 1b is an enlarged partial end view of a first corner A of the acoustic flooring system of FIG. 1A;

(4) FIG. 1c is an enlarged partial end view of a second corner B of the acoustic flooring system of FIG. 1A;

(5) FIG. 1d is an enlarged partial side view of one side of the acoustic flooring system of FIG. 1A;

(6) FIG. 1e is an enlarged partial side view of a second side of the acoustic flooring system of FIG. 1A;

(7) FIG. 2 is a cross-sectional side view of a portion of an acoustic damping building material according to a second embodiment of the present invention;

(8) FIG. 3a is a cross-sectional side view of a portion of an acoustic building damping material according to a third embodiment of the present invention;

(9) FIG. 3b is an enlarged cross-sectional side view of section A of the acoustic building damping material of FIG. 3a;

(10) FIG. 3c is a further enlarged cross-sectional side view of section B of the acoustic building damping material of FIG. 3a;

(11) FIG. 4 is a cross-sectional side view of a portion of an acoustic flooring sheet according to one embodiment of the present invention, and

(12) FIGS. 5(a) to 5(f) are a series of perspective views of the steps of installing an acoustic damping building system according to one embodiment of the present invention.

(13) Referring now to the drawings and specifically to FIG. 1A to 1e, there is shown a first embodiment of an acoustic building damping material 100 comprising a substrate 110 and an acoustic damping layer 118 secured to the substrate 110. In the embodiment shown the substrate 110 is a load bearing structural substrate in the form of a flooring sheet which is approximately 499 mm in width and 2400 mm in length. Flooring sheet 100 can support minimum static loads of 5 KPa. In this embodiment of the invention, the substrate 100 comprises a cementitious bound material, for example a fibre cement material with a density within the range of 900 to 1800100 Kg/m.sup.3.

(14) Substrate 110 comprises a first face 112, a second face 114 and an intermediate portion 116 positioned between the first and second faces and an edge member 116a, 116b surrounding the intermediate portion. In the embodiment shown the first and second faces, intermediate portion and edge member together integrally form a panel or sheet of predetermined thickness. The edge member or portion 116 of substrate layer 110 is provided with both a protruding or projecting member 116a and a receiving portion 116b, thereby comprising a tongue and groove configuration. In this embodiment of the invention the distance from the uppermost surface of the acoustic building damping material 100 to the opposing lowermost surface of the acoustic building damping material 100 is approximately 27 mm, wherein the distance from the uppermost surface of the acoustic damping layer 118 to the opposing lowermost surface of the acoustic damping layer 118 is approximately 5.0 mm and the distance from the uppermost surface of the substrate layer 110 to the opposing lowermost surface of the substrate layer 110 is approximately 22.0 mm. The edge member 116 of the substrate layer is further provided with a chamfered or bevelled edge 116c (shown clearly in FIG. 1b) at the first face 112 of the substrate layer 110. This provides a user with a slightly opened area for a sealant to be applied easily between two adjacent sheets of the acoustic damping building material 100 of the invention. The chamfered or bevelled edge 116c enables a better seal to form between the adjacent sheets.

(15) In the embodiment of the invention shown in FIGS. 1A to 1e, the acoustic damping layer 118 is secured by gluing to the first face of the substrate layer 110 such that the acoustic damping layer 118 covers predominantly all of the first face of the substrate layer 110. Acoustic damping layer 118 does not extend to cover all of the first face 112 of the substrate layer 110, this is to allow for compression of the acoustic damping layer when a load is placed on the acoustic building damping material 100 of the invention. In the embodiment shown the uncovered area between the edge of the acoustic damping layer 118 and the edge portion 116 is approximately 2.25 mm across the width of the board as shown in FIGS. 1b and 1c and approximately 2.0 mm across the length of the board as shown in FIGS. 1d and 1e.

(16) Conveniently when this embodiment of the invention is in use in a building structure, the acoustic damping layer 118 can be arranged such that the acoustic damping layer 118 is positioned between the substrate 100 and the source of the sound energy or alternatively such that the acoustic damping layer 118 is remote from the source of the sound energy, i.e. the substrate 100 is located between the acoustic damping layer 118 and the source of the sound energy.

(17) Referring now to FIG. 2 and FIGS. 3a to 3c. FIG. 2 shows a second embodiment of a portion of the acoustic damping building material 200 of the invention comprising a substrate 210 and an acoustic damping layer 218 secured thereto. FIG. 3a shows a third embodiment of a portion of the acoustic damping building material 300 of the invention comprising a substrate 310 and a first and second acoustic damping layer 318 and 320 respectively. In the second and third embodiment shown, acoustic damping layers 218, 318 and 320 cover all of substrate 210, 310 respectively. It will be appreciated that it is possible for the damping layers to cover all or at least a portion of the substrate 210, 310 respectively.

(18) In the embodiments shown, the acoustic damping layers 118, 218, 318 and 320 comprise two media wherein the media are configured such that each of the acoustic damping layers 118, 218, 318, 320 comprise at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer 118, 218, 318, 320 to the substrate 210 and 310 respectively. Although the acoustic damping layer 118, 218, 318 320 are not drawn to scale, it is to be understood that in one embodiment of the invention, the acoustic damping layer 118, 218, 318, 320 has a depth of between approximately 1 mm and 20 mm from an exterior surface to an interior surface whereby the exterior surface is defined as the surface of the acoustic damping layer remote from the substrate 210 and 310 and the interior surface of the acoustic damping layer is adjacent the substrate 210 and 310 in any given configuration. In alternative embodiments of the invention the depth of the acoustic damping layer 118, 218, 318, 320 is any distance between approximately 2 mm and 10 mm.

(19) Referring specifically to FIGS. 3b and 3c, there are shown enlarged cross sectional views of the media of the acoustic damping layers 318 and 320. In the embodiment shown acoustic damping layers 318 and 320 are substantially the same. Each of the respective media 322 and 324 used in the acoustic damping layer 318 have a different transmission coefficient () to the other and are interspersed in the acoustic damping layer 318 to form the direct and indirect energy transmission pathways. It is to be understood that the media of the acoustic damping layers can be any suitable media or material known to a person skilled in the art. In the embodiment shown, the acoustic damping layer 318 comprises a polymeric material 322 which is in the form of a plurality of particles which have been dispersed and held in place by a polymeric binder 326.

(20) The polymer particles 322 are of irregular shape, consequently interstitial void volumes 324 are present between adjacent polymer particles 322. The polymer particles 322 are dispersed amongst each other within the acoustic damping layer 318 such that in some instances, a portion of the surface area 322a of the particles 322 are contiguous to a portion of the surface area of an adjacent particle 322 of the same media. This forms a direct energy transmission pathway through the polymer media of the acoustic damping layer. Similarly, in some instances a portion of the surface area 322b of the polymer particles 322 are adjacent to a void volume 324 so as to form an indirect energy transmission pathway through the acoustic damping layer.

(21) In the embodiments of the invention shown, the polymeric material 322 is selected from the group comprising natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, EPDM, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, copolymers. The polymeric binder 326 is selected from the group comprising emulsion polymers, polymer solutions, polymer dispersions, thermosetting polymers, and thermoplastic polymers. The void volume 324 is normally occupied by a mixture of gases, for example air. In all of the above any other materials known to a person skilled in the art which would achieve the object of the invention can also be used.

(22) The void volume 324 is in effect dispersed throughout the acoustic damping layer 318 due to the arrangement of the irregularly shaped particulate polymenc material 322. Although not specifically shown in the drawings, in one embodiment of the invention, the void volume 324 occupies between 5 and 80% by volume of the acoustic damping layer. In further embodiments of the invention the void volume occupies between 10 and 50% by volume and between 15 and 35% by volume of the acoustic damping layer respectively.

(23) Referring to FIG. 4, there is shown the acoustic damping building material 300 of FIG. 3a comprising two acoustic damping layers 318 and 320 in use as a flooring material 400. The building material is secured to support 440 such that the acoustic damping layer 320 abuts the support 440 along the support surface 442. Although not shown, it is to be understood that optionally in this embodiment of the invention, acoustic damping layer 320 adjacent support 440 has a greater depth than the acoustic damping layer 318 on the opposite side of the substrate 310. In one embodiment of the invention, acoustic damping layer 318 has a depth that is approximately 2 mm whilst acoustic damping layer 320 has a depth that is approximately 5 mm. The advantage of this embodiment of the invention is that the acoustic damping layer 318 on the trafficable side of the flooring material is designed to reduce impact noise, whilst the acoustic damping layer 320 is designed to absorb, dissipate and limit the transfer of impact and vibration to the support 440 and consequently throughout the building structure.

(24) Referring now also to 5(a) to 5(f), there is shown an example of the steps of the method for installation flooring sheet 400 in a building structure. For the purposes of clarity, the acoustic damping building material 300 of FIG. 3a is shown without defining the acoustic damping layers in FIGS. 5(a) to 5(e). FIG. 5(a) is an example a building subframe structure 440. In FIGS. 5(b) to 5(d) the installer is shown reinforcing the building subframe structure 440 and securing a first and second section 300a and 300b respectively of the acoustic damping building material 300 of the invention to the building subframe structure 440 at predefined positions 440a on the subframe 440. FIG. 5(f) shows an aesthetic surface layer 332 secured to the acoustic damping building material 300 for providing an aesthetic building finish. It is to be understood that the acoustic damping building material is securable to the building subframe 440 by either mechanical or chemical means, wherein the mechanical means is selected from one or more of the group comprising nails, screws, scrails, staples, bolts, and masonry anchors; and the chemical means is by means of an appropriate adhesive.

(25) The acoustic damping building material 100, 200 or 300 of the invention were tested to determine airborne and impact transmissions. In each instance the acoustic damping building material 100, 200 or 300 was tested having either a single acoustic damping layer attached to one side of the substrate or a double acoustic damping layer wherein a single acoustic damping layer was secured to opposing sides of a substrate. In all instances the acoustic damping building material was secured to a building sub frame. The acoustic building material was also tested with and without an outer decorative surface, wherein the decorative surface was either a timber laminate or a ceramic tile as set out below. The temperature of the testing area was also recorded.

(26) Sound pressure levels are typically reported in decibel (dB) units. With 0 dB representing the threshold of audibility for a person of normal hearing capacity and 100 dB representing, say, the noise level in a subway railway station or heavy industrial machinery in operation. In a normal daily urban environment, a person may be exposed to sound levels such as average street noise at around 70 dB, an average office environment at around 60 dB, an average conversation at around 50 dB, and a quiet or private office at around 40 dB. The correlation between sound intensity and sound pressure is logarithmic and an increase of 10 dB in sound pressure level represents a 10-fold increase in sound intensity level, so the sound intensity at 100 dB is 10,000,000,000 times greater than that at OdB. For a person of normal hearing, a change of 1-2 dB is not detectable. A change of 5 dB, however, is clearly detectable and a change of 10 dB is regarded as either a halving (if reduced by 10 dB) or doubling (if increased by 10 dB) of the noise level. A relatively small change in dB sound levels may, in fact, represent a significant change in the sound intensity in an environment.

(27) Many sounds that people are exposed to in a modern environment span across a range of frequencies from about 50 Hz up to about 10 kHz. Voices are predominantly in the 100-300 Hz range. Heavy vehicles may be in the 50-1000 Hz range and car horns are in the AAA-5000 Hz range. All of the sounds in an environment may reach a person at different sound intensity depending on how far away they are from the source, any material between the person and the source of the sound that may act to absorb or transmit those sounds, and the sound travel pathways available.

(28) Each material will have a characteristic sound absorption/transmission effectiveness depending not only its inherent material properties, but also its physical configuration such as shape, thickness and the like. Sound may also be transferred either directly through the material of a building section such as a wall or floor section &/or indirectly through airborne transmission.

(29) Creating an environment for people, such as in residential dwellings or office/commercial spaces, requires that noise or sound intensity levels are managed. The ideal is to create an environment where sound intensity, through both direct and indirect transmission pathways, is below nuisance levels both for the person themselves and for any immediately adjacent neighbours.

(30) In order for the acoustic damping building material of the invention to achieve adequate noise reduction, it is necessary for the airborne noise transmission to be greater than 45 dB.

(31) The first embodiment 100 of the acoustic damping building material of the invention was tested in a combined structural floor, ceiling configuration, such a configuration is typically found between storeys of a multi-storey building construction. As set out below in Table One, the airborne noise transmission for the various embodiments of the invention is 60 and 62 Db (R.sub.w+C.sub.tr) respectively, whilst the impact noise transmission for the various embodiments of the invention is between 55 and 64 Db (L.sub.n,Tw). The results of the test exemplify that the various embodiments of the invention operated to reduce both airborne and impact acoustic, noise or sound transmissions to an acceptable level.

(32) TABLE-US-00001 TABLE ONE TEST Airbourne/ Impact/ Floor Structural Ceiling dB dB Temp/ Assembly Detail Covering Floor Configuration R.sub.w (C.sub.tr) L.sub.nT,w C. 100 Single Acoustic Joists with Insulation: 62 (9) 57 15 Damping Layer minimum 100 mm with and Fibre spacing of min value of Cement 240 mm 10 kg/m.sup.3; Substrate Resilient Bars: 27 mm 16 mm 100 Fibre Cement 0.45 mm metal 60 (10) 64 15 Substrate and resilient bar; Single Acoustic 1.sup.st and 2.sup.nd Damping Layer ceiling layers: 27 mm** 15 mm 100 Single Acoustic 6 mm Gypsum board na 55 15 Damping Layer Ceramic 912.5 Kg/m.sup.2 and Fibre tile laid on Cement flexible tile Substrate adhesive 27 mm **The single acoustic damping layer was on the lower side of the substrate layer adjacent the structural floor.

(33) The second and third embodiments (assembly) 200 and 300 respectively of the acoustic damping building material of the invention were tested at various temperatures as a flooring material to determine the effectiveness of the building material. As set out below in Table Two, the airborne noise transmission for the various embodiments of the invention is 60 and 63 Db CO respectively, whilst the impact noise transmission for the various embodiments of the invention is between 52 and 59 Db (L.sub.n,Tw). The results of the test exemplify that the various embodiments of the invention operated to reduce both airborne and impact acoustic, noise or sound transmissions to an acceptable level.

(34) TABLE-US-00002 TABLE TWO TEST Airborne/dB Impact/dB Assembly Detail Floor Covering R.sub.w (C.sub.tr) L.sub.nT, w Temp/ C. 200 Single Acoustic None 60 (8) 58 6 damping layer 200 Single Acoustic Timber laminate 62 (9) 55 6 damping layer 200 Single Acoustic Ceramic Tile Not Tested 59 6 damping layer 300 Double Acoustic None 61 (10) 59 6-7 damping layer 300 Double Acoustic Timber laminate 63 (8) 52 6-7 damping layer 300 Double Acoustic None (Room Not Tested 58 16-17 damping layer Heated) 300 Double Acoustic Ceramic Tile Not Tested 57 11 damping layer Airborne pass - >45 dB Impact Pass - <62 dB

(35) The acoustic performance of all examples provided above meet or exceed the UK Building Code ADE AAA3 (Resistance to the Passage of Sound) provisions for an L.sub.nT,w maximum value of 64 dB for floors, and stairs in buildings. (The lower the value the better). The L.sub.nT,w value is the impact sound pressure level in a stated frequency band, corrected for reverberation time, according to BS EN ISO 140-7:1998.

(36) The R.sub.w(C.sub.tr) standards for airborne noise transmission between rooms are also met or exceeded by all examples provided above. The R.sub.w (C.sub.tr) is a measure of the is the weighted sound reduction index together with the traffic A-weighted spectrum added to take account of low frequency traffic noise in airborne transmissions.

(37) It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.