GB2517125A

GB2517125A - An acoustic damping building material

Info

Publication number: GB2517125A
Application number: GB1308520.4A
Authority: GB
Inventors: James Gleeson; Karl Laing; Milton O'chee; Peter Pagones
Original assignee: James Hardie Technology Ltd
Current assignee: James Hardie Technology Ltd
Priority date: 2013-05-13
Filing date: 2013-05-13
Publication date: 2015-02-18
Also published as: GB201308520D0

Abstract

An acoustic damping building material comprising an acoustic damping layer secured to at least a portion of a substrate 310. The acoustic damping layer comprises at least two media 322, 324, preferably of different transmission co-efficient, 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 first media may be a granular particulate material such as rubber bonded together with a polyurethane, abutting neighbouring granules forming direct paths and voids forming the second media which may be air between granules forming indirect paths.

Description

AN ACOUSTIC DAMPING BUILDING MATERIAL

[0001] The present invention relates to a building material and in particular a building material that is suitable for damping acoustic resonance or sound energy.

[0002] It is recognised that acoustic resonance or noise transmissions within and between buildings is becoming a greater concern for building inhabitants, particularly as the density of habitation increases and as aesthetic tastes for hard surface finishes proliferates.

[0003] One approach to reducing noise transmission through walls and floors of buildings is to use denser materials, which inherently limit sound transmission by acting as a barrier material which reflects sound energy. Dense materials such as lead sheeting have been used in the past, but health and environmental concerns have meant that use of such materials is no longer an option. As the density of the materials increase, for example, through the use of dense concrete or masonry airborne acoustic noise or sound transmissions are significantly reduced, however, stronger foundations and other load bearing members are needed to cope with the additional weights borne by the supporting members which are used to transfer the load of the structure into the ground. This adds to the cost and complexity of construction. Furthermore use of denser materials does not address impact acoustic, noise or sound transmissions.

[0004] A further example of noise reducing techniques used during construction is found in multiple storey or multiple layer construction, where combinations of material layers are used to provide a reduction in transmitted sound intensity between storey's or layer's. An example of a multiple layer construction used in a floor/ceiling installation is exemplified in Figure 1. Referring to Figure 1, multiple layer construction 100 includes a central structural flooring sheet 10 attached to a timber frame 12, the upper side of the flooring sheet has insulation board 14 resting or secured thereon. A concrete slab 16 is provided on the upper side of the insulation board 14 remote from the central structural flooring sheet 10, the upper side of the concrete slab is further covered with an insulation mat 18 onto which a number of battens 20 are arranged and an aesthetic floor surface, for example a timber floor 22, is installed onto the battens 20. In the example shown, timber floor 22 is a veneered timber floor, comprising a core composite component 22a and a thin top wood layer 22b.

On the underside of the timber frame structure, insulation batts 24 are installed between the joints of the timber frame 12. A single or double layer of drywall, gypsum board or plasterboard 28 is then attached to the underside of the timber frame 12 to form a ceiling 30 for a lower storey. In the example shown, a flexible layer 26 is provided in between the timber frame 12 and the layer(s) of drywall or plasterboard 30. Such flooring constructions are costly and time consuming to install. Further costs are also added to the overall building costs due to the spatial area the floor/ceiling installation occupies in the building construction. The greater the distance between the ceiling 30 and the veneered timber floor 22, the greater the height of the building. This is necessary to ensure that the height of each storey or floor provides sufficient or the required amount of space for the occupants of the construction on each storey or floor.

[0005] A further noise reducing technique requires the use of roll out thin mats, which are placed between a pre-existing building substrate and an aesthetic surface layer. These mats may be compressed at the point(s) where a building sheet is fixed to a subframe through the mat. It is understood, that use of such measures does not effectively reduce transmission of sound energy within the construction.

[0006] It is an object of the present invention to overcome or ameliorate at least one disadvantage of the prior art or to provide a useful alternative.

[0007] According to the invention, there is provided an acoustic damping building material comprising: a substrate and an acoustic damping layer, the acoustic damping layer being secured to at least a portion of the substrate, the acoustic damping layer comprising 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.

[0008] The advantage of the acoustic building material of the invention is that a single product provides multiple combinations of structure borne energy transmission pathways through which sound energy can be absorbed and/or transmitted. The acoustic building material of the invention comprises at least two differing media or materials comprising different properties which in turn generate multiple combinations of structure borne energy transmission pathways through which sound energy can be absorbed and/or transmitted. In use, the acoustic damping layer provides methods by which sound fluctuations can be absorbed and/or dissipated whilst the substrate layer provides a barrier material which reflects sound fluctuations back into the acoustic damping layer. The reflected sound fluctuations are then also absorbed and dissipated. In this way, acoustic noise can be limited via impact and acoustic or vibrational transfer of sound energy through the building structure.

[0009] It is acknowledged that the term comprise' may, under varying jurisdictions be provided with either an exclusive or inclusive meaning. For the purpose of this specification, the term comprise shall have an inclusive meaning that it should be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components. Accordingly, the term comprise' is to be attributed with as broad an interpretation as possible within any given jurisdiction and this rationale should also be used when the terms comprised' and/or comprising' are used.

(0010] It is to be understood that throughout the specification, the term direct energy transmission pathway is used to describe a transmission pathway through the acoustic damping layer that enables energy to proceed through the media following a relatively straight course i.e. a pathway that is without interruption. In contrast the term indirect energy transmission pathway is used to describe a transmission pathway through the acoustic damping layer that does not follow such a course, i.e. may include one or more interruptions.

(0011] In a further embodiment of the invention, the at least two media are interspersed amongst each other to form the direct and indirect energy transmission pathways.

(0012] In one embodiment of the invention the acoustic damping layer comprises at least two media wherein one of the at least two media comprises a different transmission coefficient (T) to the other of the at least two media.

(0013] In a further embodiment of the invention, the acoustic damping layer is configured to have an outwardly appearing continuous line. In this way, the indirect and direct energy transmission pathways within the acoustic damping layer are not readily visible to the end user.

(0014] In a further embodiment of the invention one of the at least two media comprise a polymeric material and the other of the at least two media comprises a void volume, wherein the void volume is understood to be a volume of space dispersed within the polymeric material. In one embodiment of the invention, the at least one polymeric material comprising a polymeric particulate material. In a further embodiment of the invention, the at least one polymeric particulate material comprises a plurality of particles dispersed within the at least one acoustic damping layer. In a further embodiment of the invention the polymeric material is a granular material whereby the granular material is composed of small and independent granules. Optionally the particles and/or granules have different shapes, for example, either regular or irregular shapes. In one embodiment of the invention the particles or granules are formed by crumbing or shredding a piece of the polymeric material. Conveniently in a further embodiment of the invention, the polymeric particles or granules comprise a mixture of crumbed or shredded particles or granules. In a further embodiment of the invention the void volume is occupied by a fluid. In one embodiment of the invention, the fluid is a single gas or a mixture of gases.

(0015] In a further embodiment of the invention, the polymeric material is selected from the one or more of the group comprising natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, EPDM, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, copolymers.

(0016] In a further embodiment of the invention, the acoustic damping layer further comprises a polymeric binder, wherein the polymeric binder is selected from the group comprising emulsion polymers, polymer solutions, polymer dispersions, thermosetting polymers, and thermoplastic polymers. In one embodiment of the invention, the polymeric binder is used to bind the polymeric particles of the at least two media together. In a further embodiment of the invention the polymeric binder comprises a mixture of a polymeric resin, water and one or more additives wherein the one or more additives are selected from the group comprising flow control agents, rheology modifiers, fire retardants, preservatives, fungicides, insecticides, pigments, colorants, water repelling agents and any other suitable additive known to a person skilled in the art. The polymeric binder can have a different or the same transmission coefficient (T) as compared to each or both of the at least two media.

(0017] In a further embodiment of the invention,one of the at least two media comprises a plurality of particles and the other of the at least two media comprises either a plurality of particles or a void volume wherein the particles of the at least two media or the particles of one of the at least two media and the void volume are dispersed amongst each other within the acoustic damping layer such that a portion of the particles of one of the at least two media are contiguous to an adjacent particle of the same media so as to form a direct energy transmission pathway through one of the at least two media of the acoustic damping layer and a portion of the particles of one of the at least two media are contiguous to an adjacent particle of the other of the at least two media or a void volume so as to form an indirect energy transmission pathway through one of the at least two media of the acoustic damping layer.

[0018] In a further embodiment of the invention, one of the at least two media comprises between approximately 5% and 80% ± 2% by volume of the acoustic damping layer. In a further embodiment of the invention, one of the at least two media comprises between approximately 10% and 70% ± 2% by volume of the acoustic damping layer. In a further embodiment of the invention, one of the at least two media comprises between approximately 15% and 70% ± 2% by volume of the acoustic damping layer. In the preferred embodiment of the invention, the void volume comprises between approximately 5% and 80% ± 2% by volume, preferably between approximately 10% and 70% ± 2% by volume and more preferably between approximately 15% and 70% ± 2% by volume of the acoustic damping layer. In a further embodiment of the invention the polymeric binder comprises between approximately 10% to 50% ± 2% by volume of the acoustic damping layer. In one embodiment of the invention the acoustic damping layer comprises a mixture of crumbed and shredded polymeric material, a void volume and a polymeric binder wherein the crumbed and shredded polymeric material comprise approximately 60% ± 2% by weight of the acoustic damping layer and the polymeric binder comprises approximately 40% ± 2% by weight of the acoustic damping layer. In this embodiment of the invention, the ratio of crumbed polymeric material to shredded polymeric material is 1:1.

[0019] In one embodiment of the invention, 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. In this embodiment of the invention, the first and second faces are opposing faces of the panel or sheet. In a further embodiment of the invention the intermediate portion and edge portion are integrally formed with the first and second faces of the substrate. In a further embodiment of the invention the substrate comprises fibre cement material.

[0020] In a further embodiment of the invention the acoustic damping layer is secured to at least a portion of the first face of the substrate. Conveniently when this embodiment of the invention is in use in a building structure, the acoustic damping building material can be arranged such that the acoustic damping layer is positioned between the substrate and the source of the sound energy or alternatively such that the acoustic damping layer is remote from the source of the Sound energy, i.e. the substrate is located between the acoustic damping layer and the source of the sound energy. Advantageously, when the acoustic damping layer is positioned between the substrate and the source of sound energy, the direct and indirect energy transmission pathways of the acoustic damping layer operate to absorb and/or dissipate a significant amount of sound energy before the sound energy reaches the substrate layer.

[0021] In a further embodiment of the invention 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.

Conveniently separate acoustic damping layers can be provided for the first and second face of the substrate respectively. The advantage of this embodiment of the invention is that any noise or sound energy which is transmitted through a first acoustic damping layer and the substrate is absorbed by the second acoustic damping layer on the opposite face.

[0022] In one embodiment of the invention, the acoustic damping layer is between approximately 1mm and approximately 20mm thick. In a further embodiment of the invention, the at least one acoustic damping layer is between approximately 2mm and approximately 10mm thick. The advantage of this is that the acoustic damping layer is a thin layer which when combined with the substrate layer of the invention achieves acoustic damping/noise reduction without occupying a large spatial area. An acoustic damping building material of 16mm to 70mm thickness, according to the invention, can be achieved compared to more than 200mm thickness in prior art systems.

[0023] According to one embodiment of the invention, the substrate comprises a density within the range of 900 to 1800 ± 100 Kg/m3. The advantage of using a denser material is that is reduces airborne acoustic. noise or sound transmissions.

[0024] According to one embodiment of the invention, the substrate comprises a cementitious bound material. In a further embodiment of the invention, the cementitious bound material comprises a fibre cement panel or sheet, for example, a fibre cement flooring sheet or a fibre cement building panel.

[0025] The advantage of using a cementitious bound material as a substrate is that it provides a durable and workable material which has greater density than most wooden substrates normally used in construction. The cementitious bound material substrate together with acoustic damping layer of the invention provide an acoustic damping building material that reduces both airborne and impact acoustic, noise or sound transmissions [0026] In a further embodiment of the invention, the predetermined thickness of the substrate panel or sheet is between approximately 15mm and approximately 50mm.

[0027] In a further embodiment of the invention the edge portion of the substrate further comprises a protruding or projecting member which extends beyond the edge of the first and/or second face of the substrate. In a further embodiment of the invention the edge portion further comprises a receiving portion which is sized and shaped such that it is adapted to receive a complimentary shaped protruding or projecting member extending beyond the edge of the first and/or second face of the substrate. Conveniently, in a further embodiment of the invention the edge portion of a substrate layer is provided with both a protruding or projecting member and a receiving portion. In such an arrangement the protruding or projecting member and receiving portion are arranged on the edge portion such that the protruding or projecting member can seat into a receiving portion of an adjacent substrate layer when two or more substrate layers are seated together in a nested arrangement. In a further embodiment of the invention, the protruding or projecting member of the substrate and/or the receiving portion are configured to facilitate provision of a cavity intermediate the protruding or projecting member and the receiving portion, such that a securing material such as a sealant or adhesive can be placed in the cavity. The securing material acts to secure two or more substrate layers together in a nested arrangement. A further advantage of this configuration is that the securing material can also act as an acoustic damping material.

[0028] In a further embodiment of the invention, the acoustic damping building material further comprises an outer layer, wherein the outer layer is provided on the outermost surface of the acoustic damping building material which is normally visible to the end user.

Conveniently, the outer layer provides a smoother and more durable surface for the end user, for example, an aesthetic coating such as a skimmed coating of a cementitious material or a flooring surface. It is to be understood that any suitable outer layer known to a person skilled in the art which will achieve the function of the outer layer can also be used.

In one embodiment of the invention, the outer layer comprises an optimising layer and a finishing layer, wherein the optimising layer is used to improve surface flatness for the finishing layer. An example of such an embodiment of the invention is the use of a screed as the optimising layer to improve surface flatness and provide structural support for a tile finishing layer. It is to be understood that the acoustic properties of the acoustic damping building material are maintained when using an outer layer.

(0029] According to the invention, there is further provided an acoustic damping building system comprising: a building subframe structure, at least one section of acoustic damping building material according to the invention comprising: a substrate and an acoustic damping layer, the acoustic damping layer being secured to at least a portion of the substrate, the acoustic damping layer comprising 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, the or each section of acoustic damping building sheet being securable to the building subframe structure, and an aesthetic surface layer securable to the or each acoustic damping building sheet, for providing an aesthetic building finish.

(0030] The advantage of the acoustic damping building system of the invention is that the acoustic energy generated directly or indirectly within the aesthetic surface layer is damped by the or each acoustic damping building material section, which leads to abatement of acoustic noise transmission to adjacent room spaces through the building subframe structure.

(0031] In one embodiment of the invention, the acoustic damping building material is securable to the building subframe by mechanical means, wherein the mechanical means is selected from one or more of the group comprising nails, screws, scrails, staples, bolts, and masonry anchors. Optionally, in one embodiment of the invention, the acoustic damping building material is securable to the building subframe by a concealed fixing system. In a further embodiment of the invention, the acoustic damping building material is securable to the building subframe by chemical means, for example, by means of an adhesive. In a further embodiment of the invention, the acoustic damping material is securable to the building subframe using a combination of mechanical and chemical means.

(0032] According to the invention, there is provided a method of constructing an acoustic damping building system comprising the steps of (a) providing a building subframe structure; (b) providing at least one section of acoustic damping building material according to the invention, the acoustic damping building material comprising: a substrate and an acoustic damping layer, the acoustic damping layer being secured to at least a portion of the substrate; the acoustic damping layer comprising 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; (c) Installing a section of the acoustic damping building material by positioning the acoustic damping building material into a user selectable position on the building subframe and securing it to the building subframe; and (d) applying and securing a surface layer to the acoustic damping layer on the acoustic damping building material to provide an aesthetic finish.

[0033] In one embodiment of the invention, the method of constructing an acoustic damping building system further comprises after step (c) the further steps of: (cl)Securing a subsequent section of the acoustic damping building material onto the building subframe relative to the previously installed section of acoustic damping building material, and securing it to the building subframe, (c2)Repeat step (ci) until the desired building section is covered.

[0034] In one embodiment of the invention, the acoustic damping building material is securable to the building subframe by mechanical means, wherein the mechanical means is selected from one or more of the group comprising nails, screws, scrails, staples, bolts, and masonry anchors. Optionally, in one embodiment of the invention, the acoustic damping building material is securable to the building subframe by a concealed fixing system. In a further embodiment of the invention, the acoustic damping building material is securable to the building subframe by chemical means, for example, by means of an adhesive. In a further embodiment of the invention, the acoustic damping material is securable to the building subframe using a combination of mechanical and chemical means.

[0035] In a further embodiment of the invention, the acoustic damping building material is suitable for use in combination with other acoustic damping building materials. In particular the acoustic damping building material of the invention is suitable for use with an acoustic dampener comprising: a base member, wherein the base member comprises a first surface and a second surface, the first and second surface being spaced apart from each other defining a thickness therebetween; at least two side arms, wherein each side arm comprises a first end and a second end, each side arm extending from the first surface of the base member at a pre-determined angle, such that there is a channel formed whereby each side arm and the base member form the sides and the base of the channel formation respectively; and a pair of flanges, each flange extending substantially orthogonally from the second end of each side arm and wherein the predetermined angle is elastically deformable. In this embodiment of the invention the channel formation is configured to receive a batten and the or each flange is configured to retain a batten within the channel.

[0036] According to a further embodiment of the invention there is also provided a floor structure comprising acoustic damping building material and an acoustic dampener securable to a structural substrate, a batten disposed within the channel formation and flooring material secured to the batten.

(0037] Other advantages of the invention are that the acoustic damping building material provides a lightweight alternative to other acoustic damping systems, which do not require application of multiple layers or skills from different trades. Use of a single layer of material, and the associated reduction in spacing between floors or walls means a reduction in building and materials costs which is hugely advantageous for the end user.

(0038] The invention will now be described more particularly with reference to the accompanying drawings, which show by way of example only two embodiments of the acoustic damping building material of the invention.

(0039] In the drawings, (0040] Figure 1 is a cross-sectional side view of an acoustic flooring system according to the prior ad; (0041] Figure 2 is a cross-sectional side view of a portion of an acoustic damping building material according to a first embodiment of the present invention; (0042] Figure 3a is a cross-sectional side view of a portion of an acoustic building damping material according to a second embodiment of the present invention; (0043] Figure 3b is an enlarged cross-sectional side view of section A of the acoustic building damping material of Figure 3a; (0044] Figure 3c is a further enlarged cross-sectional side view of section B of the acoustic building damping material of Figure 3a; [0045] Figure 4 is a cross-sectional side view of a portion of an acoustic flooring sheet according to one embodiment of the present invention, and [0046] Figures 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.

[0047] Referring now to the drawings and specifically to Figure 2 and Figures 3a to 3c.

Figure 2 shows a first 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. Figure 3a shows a second 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 embodiment's 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 or at least a portion of the substrate 210, 310 respectively.

[0048] In the embodiments shown in Figures 2 and 3a, the acoustic damping layers 218, 318 and 320 comprise two media wherein the media are configured such that each of the acoustic damping layers 218, 318, 320 comprises at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer 213, 318, 320 to the substrate 210 and 310 respectively. Although the acoustic damping layer 218, 318 320 shown in Figures 2 and 3a are not drawn to scale, in one embodiment of the invention the acoustic damping layer 218, 318, 320 is between approximately 1mm and 20mm thick. In an alternative embodiment of the invention the acoustic damping layer 218, 318, 320 is between approximately 2 and 10mm thick.

[0049] Referring specifically to Figures 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 (i) 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.

(0050] 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.

(0051] 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.

(0052] 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.

(0053] Referring now to Figures 4 and 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 is shown without defining the acoustic damping layers in Figures 5(a) to S (e). Figure 5(a) is an example a building subframe structure 440. In Figures 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 on the subframe 440. Figure 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.

[0054] Referring to Figure 4, there is shown the acoustic damping building material 300 comprising two acoustic damping layers 318 and 320 in use as a flooring material. The building material is secured to support 440 such that the acoustic damping layer 320 abuts the support 440 along the support surface 442. In this embodiment of the invention the acoustic damping layer 320 is preferably thicker than the acoustic damping layer 318. In one embodiment of the invention acoustic damping layer 318 is approximately 2mm thick whilst acoustic damping layer 320 is approximately 5mm thick. 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.

[0055] The first and second 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. The test product and measured airboume and impact transmissions are set out in Table One below.

[0056] TEST-TABLE ONE Assembly Detail Floor Covering Airborne/dB lmpact/dB TempPC Single Acoustic None 52 58 6 _____________ damping_layer __________________ ___________ __________ ________ Single Acoustic Timber laminate 53 55 6 _____________ damping_layer __________________ ___________ __________ ________ Single Acoustic Ceramic Tile Not Tested 59 6 _____________ damping_layer __________________ ___________ __________ ________ 300 Double None 51 59 6-7 Acoustic _____________ damping_layer __________________ ___________ __________ ________ 300 Double Timber laminate 55 52 6-7 Acoustic _____________ damping_layer __________________ ___________ __________ ________ 300 Double None (Room Not Tested 58 16-17 Acoustic Heated) _____________ damping_layer __________________ ___________ __________ ________ 300 Double Ceramic Tile Not Tested 57 11 Acoustic _____________ damping_layer __________________ ___________ __________ ________ Airborne pass ->45dB Impact Pass -<62dB [00571 The acoustic damping building material of the invention having either a single acoustic damping layer 200 or a double acoustic damping layer 300 was secured to a building sub frame. The building material was then tested to determine airborne and impact transmissions without an outer surface and with an outer surface wherein the outer surface was either a timber laminate or a ceramic tile. The temperature of the area was recorded.

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 45dB whilst the impact noise transmission should be less than 62dB. As set out above in Table One! the airborne noise transmission for the various embodiments of the invention is between 51 and DB, whilst the impact noise transmission for the various embodiments of the invention is between 52 and 59 DB. 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.

[00581 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.

Claims

Claims: 1. An acoustic damping building material comprising; a substrate and an acoustic damping layer, the acoustic damping layer being secured to at least a portion of the substrate, the acoustic damping layer comprising 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.
2. An acoustic damping building material as claimed in Claim 1, wherein the at least two media are interspersed amongst each other to form the direct and indirect energy transmission pathways.
3. An acoustic damping building material as claimed in Claim 1 or Claim 2, wherein one of the at least two media comprises a plurality of particles and the other of the at least two media comprises either a plurality of particles or a void volume wherein the particles of the at least two media or the particles of one of the at least two media and the void volume are dispersed amongst each other within the acoustic damping layer.
4. An acoustic damping building material as claimed in Claim 3, wherein the particles of the at least two media or the particles of one of the at least two media and the void volume are dispersed amongst each other within the acoustic damping layer such that a portion of the particles of one of the at least two media are contiguous to an adjacent particle of the same media so as to form a direct energy transmission pathway through one of the at least two media of the acoustic damping layer and a portion of the particles of one of the at least two media are contiguous to an adjacent particle of the other of the at least two media or a void volume so as to form an indirect energy transmission pathway through one of the at least two media of the acoustic damping layer.
5. An acoustic damping building material as claimed in any one of the preceding claims, wherein the acoustic damping layer comprises at least two media wherein one of the at least two media comprises a different transmission coefficient (i) to the other of the at least two media.
6. An acoustic damping building material as claimed in any one of the preceding claims, wherein one of the at least two media comprise a polymeric material and 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 at least one polymeric material comprising a polymeric particulate material or a granular material.
8. An acoustic damping building material as claimed in Claim 6 or Claim 7, wherein the polymeric material is selected from the group comprising natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, EPDM, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, copolymers.
9. An acoustic damping building material as claimed in Claim 6, Claim 7 or Claim 8, wherein the void volume is occupied by a fluid.
10. An acoustic damping building material as claimed in any one of the preceding claims, wherein the acoustic damping material further comprises a polymeric binder, selected from the group comprising emulsion polymers: polymer solutions, polymer dispersions, thermosetting polymers, and thermoplastic polymers.
11. An acoustic damping building material as claimed in any one of the preceding claims, wherein one of the at least two media comprises between 5% and 80% ± 2% of the acoustic damping layer.
12. An acoustic damping building material as claimed in any one of Claims 1 to 10, wherein one of the at least two media comprises between 10% and 70% ± 2% by volume of the acoustic damping layer.
13. An acoustic damping building material as claimed in any one of Claims 1 to 10, wherein one of the at least two media comprises between 15% and 70%± 2% by volume by volume of the acoustic damping layer.
14. An acoustic damping building material as claimed in any one of the preceding claims, 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.
15. An acoustic damping building material as claimed in Claim 14, wherein the predetermined thickness of the substrate panel or sheet is between approximately 15mm and approximately 50mm.
16. An acoustic damping building material as claimed in Claim 14 or Claim 15, wherein the intermediate portion and edge portion are integrally formed with the first and second faces of the substrate.
17. An acoustic damping building material as claimed in any one of Claims 14 to 16, wherein the acoustic damping layer is secured to at least a portion of the first face of the substrate.
18. An acoustic damping building material as claimed in any one of Claims 14 to 16, 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.
19. An acoustic damping building material as claimed in any one of the preceding claims, wherein the substrate comprises a material having a density between 900 and 1800 kg/m3.
20. An acoustic damping building material as claimed in any one of the preceding claims, wherein the substrate comprises a cementitious bound material.
21. An acoustic damping building material as claimed in Claim 20, wherein the cementitious bound material comprises a fibre cement panel or a fibre cement sheet.
22. An acoustic damping building system comprising: a building subframe structure, at least one section of an acoustic damping building material according to any one of the preceding claims, the or each section of acoustic damping building sheet being securable to the building subframe structure, and an aesthetic surface layer securable to the or each acoustic damping building sheet, for providing an aesthetic building finish.
23. A method of constructing an acoustic damping building system comprising the steps of: (a) providing a building subframe structure; (b) providing at least one section of acoustic damping building material according to the invention, the acoustic damping building material comprising: a substrate and an acoustic damping layer, the acoustic damping layer being secured to at least a portion of the substrate; the acoustic damping layer comprising 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; (c) Installing a section of the acoustic damping building material by positioning the acoustic damping building material into a user selectable position on the building subframe and securing it to the building subframe; and (d) applying and securing a surface layer to the acoustic damping layer on the acoustic damping building material to provide an aesthetic finish.
24. A method of constructing an acoustic damping building system as claimed in Claim 21, the method comprising after step (c) the further steps of: (ci) Securing a subsequent section of the acoustic damping building material onto the building subframe relative to the previously installed section of acoustic damping building material, and securing it to the building subframe, (c2) Repeat step (ci) until the desired building section is covered.
25. An acoustic damping building material substantially in accordance with any of the embodiments as herein described with reference to and as shown in the accompanying drawings.
26. An acoustic damping building system comprising an acoustic damping building material substantially in accordance with any of the embodiments as herein described with reference to and as shown in the accompanying drawings.
27. A method of constructing an acoustic damping building system comprising an acoustic damping building material substantially in accordance with any of the embodiments as herein described with reference to and as shown in the accompanying drawings.