Composite building panel and shell

Abstract

The present invention provides an outer shell for a composite building panel having an outwardly extending tongue and correspondingly shaped inwardly extending groove formed on opposite side edges the

Description

Field of the invention The present invention relates to composite building panels, particularly to composite building panels of the type that have an outer shell and a concrete infill material. The present invention also relates to shells for composite building panels. Background Composite building panels of the type that typically have a sheet metal outer shell that is then infilled with a concrete material are well known. Typically, these panels have a rectangular side profile and include, along side edges, corresponding tongue and grove features to allow for interlocking of like panels to form a wall. International patent application no. PCT / AU2019 / 050042 to the present Applicant, the entire contents of which are incorporated by reference herein, is a good example of such a panel. Figures 1 and 2 of the present application illustrate a panel of this type and a small wall constructed of panels of this type. Such panels are very effective at resisting fire and can have a very long time to complete failure once compromised as they maintain their structural integrity. Even if significant cracks occur in a wall made of such panels (which typically occur at the join) and flames and / or gases can pass through, the remainder of the wall will remain in place so that only a small amount of flames / gases are able to pass through, thereby restricting the spread of fire. Accordingly, a fire can burn within the building without catastrophic failure and even during a large-scale fire, the wall contributes to the structural integrity of the building even when damaged. This is in contrast to plaster panels having a fire-resistant coating, which tend to reach catastrophic failure very quickly once the coating has been damaged and the core of the material is exposed to the fire and heat. It has been observed that in most building fires there is a limited availability of fuel so that if the walls can remain in place without failure, the fire will eventually burn out without catastrophic building failure. This is particularly true in apartment complexes where previous fires have led to wall failure and then spread quickly through the building, leading to large human and financial cost. Furthermore, due to their strength composite panels having a sheet metal outer shell and concrete infill are better able to resist seismic loading without catastrophic failure compared to other commonly used internal wall systems. Even if a small amount of damage occurs during the seismic event the fire rating of the wall remains high, which is important as fires often follow seismic events. Consequent to building fire safety standards increasing in Australia, there is a requirement that temperatures on a non-fire side of the panel remain low even after the fire side of the panel has been subject to temperatures that increase to between 1000 and 1200 degrees Celsius over a period of three hours. Such high temperatures can cause buckling of the wall panel, potentially letting hot gases pass through a joint between adjacent panels. There is a need to address the above, and / or at least provide a useful alternative. Summary According to one aspect of the invention there is provided an outer shell for a composite building panel having an outwardly extending tongue and correspondingly shaped inwardly extending groove formed on opposite side edges thereof for interlocking like panels to form a wall, wherein the shell has at least one sealing groove formed in either the tongue or groove for receipt of an intumescent seal extending along a length of the panel for sealing between adjacent panels. According to some embodiments of the invention, the sealing groove is formed in a tip of the tongue at a central location or at a corresponding location in the groove. In another embodiment, two sealing grooves are formed in either opposite sides of the tongue or in opposing sides of the groove. Preferably, the sealing grooves are formed at a location proximal to an interface between the panels where external surfaces of the panels meet. Preferably, a depth of the sealing groove(s) is such that a seal having a thickness in the range of 1mm to 5mm is provided. In preferred embodiments, the location and size of the sealing groove is selected so that the seal reaches a temperature of 180 degrees Celsius within 50 minutes of a test according to AS 1530.4:2014. Preferably, the tongue has a forward portion with parallel sides which are substantially straight and substantially parallel to a central plane of the panel, an intermediate portion including tapering walls which taper outwardly from the parallel sides away from the central plane towards side faces of the panel, and a rearward portion also with parallel sides extending from the intermediate portion to the side faces of the panel, wherein inner faces of the groove have parallel sides and a tapered intermediate portion that are configured for engagement with the tongue of a like panel by abutting against corresponding forward and rearward portions and a tapered intermediate portion of the tongue of the like panel. According to another aspect of the invention, there is provided a composite building panel comprising an outer shell of the above described type; a concrete infill material; and an intumescent seal extending along the sealing groove. According to a preferred embodiment, the intumescent seal is configured to activate at over 180degrees Celsius. Preferably, the seal has a cross sectional thickness in the range of 1mm to 5mm and a cross sectional width in the range of 3mm to 12mm. Preferably, the location and size of the seal is selected so that the seal reaches a temperature of 180 degrees Celsius within 50 minutes of a test according to AS 1530.4:2014. Brief description of the drawings In order that the invention may be more easily understood, an embodiment will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of prior art panel; Figure 2 is a sectional view of a prior art panel; Figure 3 is a perspective view of three prior art panels connected to form a wall; Figure 4 is a close sectional view of two panels according to a preferred embodiment of the invention connected together; and Figure 5 is a close sectional view of two panels according to another embodiment of the invention connected together. Detailed description For the purposes of context, Figure 1 illustrates a prior art composite building panel 1. The panel 1 includes an outer shell 3 which is completely filled with a suitable concrete infill material 5. In this embodiment the panel is rectangular shaped, and includes a tongue portion 7 extending outwardly from one side edge of the panel 1 and a correspondingly configured groove portion 9 extending outwardly from an opposite side edge, whereby the tongue 7 of one panel can be received in the groove 9 of a like panel for interlocking like panels together to form a wall. Preferably, the tongue 7 and groove 9 are sized so that the tongue 7 is a tight fit into groove 9. The tongue 7 extends outwardly from the side edge of the panel 1 and has a forward portion 15 with parallel sides 17 (Figure 2) which are substantially straight and substantially parallel to a central plane of the panel 1, thereby creating a square or rectangular profile. In the illustrated embodiment, the tongue 7 extends along a central plane of the panel 1, i.e. the parallel sides 17 are equidistant from the central plane, though it will be appreciated that in other embodiments, the tongue 7 may be offset to one side of the central plane. The parallel sides 17 may be 12 to 30mm long. The tongue 7 has an intermediate portion 19 with side walls 20 that taper outwardly from the parallel sides 17 toward respective side faces 21 of the panel 1. It will be appreciated that the intermediate potion 19 may not extend all the way to the side faces 21. In the illustrated embodiment, walls 20 transition into an "S" shape before reaching the side faces 21. In this regard, a rearward portion 22 also with parallel sides 24 is disposed between the intermediate portion 20 and the side faces 13. Importantly, inner faces 23 of the groove 9 are configured for close engagement of the forward, intermediate and rear portions 15, 19, 22 of the tongue 7. This straight / wedge / straight wall configuration on the tongue can result in superior fitment of like panels. In this regard, the initial straight section, forward portion 15, allows for an improved structural interlock between the panels. The wedge, intermediate portion 19, allows for two like panels to fit snugly together, providing a good air seal. Rearward portion 22 also provides an improved structural interlock, as well as a flat face that allows screws to be used to secure two like panels together. The combination of these features provides a greatly improved connection over the prior art. Preferably, the intermediate portion 19 is between 20 and 45mm long, with side walls 20 having a taper angle in the order of 3 to 30 degrees. Rear portion 24 is also preferably between 12 and 30mm long. The shell 3 is formed from a sheet material, which is preferably sheet metal, and which is preferably 0.2 to 0.7mm thick. The shell 3 is formed from multiple parts that come together with a male / female interlocking fit. The location of the edges of each sheet is selected to create a stiffer panel at the point where loading is high, particularly near the tongue portion 7 and groove portion 9. To further stiffen the panel, ripples or folds 25 may also be formed in the shell 3. Ripples 25 are provided near the groove portion 9 to further enhance the strength of the panel, particularly to prevent opening of the groove portion 9. Figures 4 and 5 illustrate a panel 100 according to a preferred embodiment of the invention. Panel 100 is similarly configured to panel 1 and like features are indicated with reference numerals incremented by 100. For brevity, a full description of the features of panel 100 is omitted, with the preceding description of like features intended to apply. Panel 100 has a shell 103 with at least one sealing groove 130 formed in either the tongue or groove for receipt of an intumescent seal extending along a length of the panel for sealing between adjacent panels. The inventor has found that when very high temperatures are applied to one side of a wall formed of panel 100, such as under test AS 1530.4:2014 where temperatures of between 1000 and 1200 degrees Celsius are applied, panel 100 will bow towards the heated side after some time has passed. Such an issue was not previously encountered as previous test requirements were much lower and during a shorter test, deflection of a wall formed by panel 100 was less severe. Initially, under such conditions, the concrete within the panel breaks down, releasing water molecules which evaporate as steam, thereby keeping a temperature of the panel low. Once the moisture has been driven out, the temperature of panel 100 starts to rise, leading to bowing of the wall towards a fire-side of the wall. The inventor has observed that as the wall bows, localised hot spots form on a non-heated side of the panel, due to hot gases finding a path from the fire side to a non fire side through the joint between adjacent panels. To meet the standards prescribed under test AS 1530.4:2014 it is necessary to prevent the passage of these gases through the joint. To this end, an intumescent seal is proposed within a joint between each adjacent panels, the seal sitting in a sealing groove 130 and being formed of a liquid material applied to the panel 100 during manufacture. The seal expands under high temperature to close off gaps formed between the panel due to deflection of the panels, thereby reducing the ability for gasses to pass through the panel. This reduces fire transmission between rooms of the building and overall fire spread. In addition to deflection of the panel due to heat during a fire, it will be appreciated that the building itself may move due to heat stress on the structure. The present seal can reduce the spread of fire in such circumstances as providing an intumescent seal allows for this deflection to be accommodated and the fire safety performance improved over the prior art. Also, deflection of the building may be the result of seismic activity and the severity of fires arising after such activity can be reduced due to the closing off of gaps formed between the panels. In the example of Figure 4, the sealing groove 130 is formed in a tip of the tongue 7 at a central location or at a corresponding location in the groove 9. In the example of Figure 5, two sealing grooves 130 are formed in either opposite side of the tongue 7 or in opposing sides of the groove 9. It will be appreciated that in the different embodiments, the sealing groove 130 may be provided in either the tongue 7 or groove 9, or both. When formed in both the tongue 7 and groove 9, the sealing groove will be smaller with sealing material potentially inserted into each groove. If a sealing groove 130 is not provided in a generally central location, two sealing grooves 130 must be provided, one on either side of a centreline of the panel. If a seal is provided on a single side of the joint, the fire safety performance of the joint will vary from side to side as the time for the seal to heat up and expand will be different. Preferably, the seal / sealing groove 130 is formed at a location proximal or near to an interface between the panels where external surfaces of the panels meet. In this regard, the seal is close to the interface so as to heat up and expand before hot gases can penetrate far into the joint. If the seal is embedded deep within the joint, i.e. away from the interface between the panels where external surfaces of the panels meet, the panel will have to heat to a higher temperature before the seal reaches a sufficient temperature for activation, at which time deflection of the panel may be greater, placing greater strain on the seal which is required to close a potentially larger gap. Preferably, the seal will be activated and acting to seal the joint prior to 80% of panel deflection occurring. In a preferred form, the location and size of the sealing groove 130 is selected so that the seal reaches a temperature of 180 degrees Celsius within 50 minutes of a test according to AS 1530.4:2014. In a preferred form a depth of the sealing groove(s) 130 is such that a seal having a thickness in the range of 1mm to 5mm is provided. The sealing material may be a commercially available material which is preferably graphite based. Examples of such materials are Calcium Carbonate, Acrylic Polymers, Aluminium Hydroxide, Hydrocarbons, Sodium Hydroxide, Graphite, Melamine , Polypropylene Glycol Alkyl Phenol Ether, though it will be appreciated that other materials may also be suitable. The ratio of material and percentage used will vary according to the material type selected to achieve a desired expansion and fire resistance. Typically the required rate of expansion in fire is between 1 and 15 times, with the ideal rate being six times original volume. Many modifications of the above embodiments will be apparent to those skilled in the art without departing from the scope of the present invention. 5 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. 10 The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge 15 in the field of endeavour to which this specification relates.

Claims

1. An outer shell for a composite building panel having an outwardly extending tongue and correspondingly shaped inwardly extending groove formed on opposite side edges thereof for interlocking like panels to form a wall, wherein the shell has at least one sealing groove formed in either the tongue or groove for receipt of an intumescent seal extending along a length of the panel for sealing between adjacent panels.

2. An outer shell for a composite building panel according to claim 1, wherein the sealing groove is formed in a tip of the tongue at a central location or at a corresponding location in the groove.

3. An outer shell for a composite building panel according to claim 1, including two sealing grooves formed in either opposite sides of the tongue or in opposing sides of the groove.

4. An outer shell for a composite building panel according to claim 3, wherein the sealing grooves are formed at a location proximal to an interface between the panels where external surfaces of the panels meet.

5. An outer shell for a composite building panel according to any preceding claim, wherein a depth of the sealing groove(s) is such that a seal having a thickness in the range of 1mm to 12mm is provided.

6. An outer shell for a composite building panel according to any preceding claim, wherein the location and size of the sealing groove is selected so that the seal reaches a temperature of 180 degrees Celsius within 50 minutes of a test according to AS 1530.4:2014.

7. An outer shell for a composite building panel according to any preceding claim, wherein the tongue has a forward portion with parallel sides which are substantially straight and substantially parallel to a central plane of the panel, an intermediate portion including tapering walls which taper outwardly from the parallel sides away from the central plane towards side faces of the panel, and a rearward portion also with parallel sides extending from the intermediate portion to the side faces of the panel, wherein inner faces of the groove have parallel sides and a tapered intermediate portion that are configured forengagement with the tongue of a like panel by abutting against corresponding forward and rearward portions and a tapered intermediate portion of the tongue of the like panel.

8. A composite building panel comprisingan outer shell according to any preceding claim;5 a concrete infill material; andan intumescent seal extending along the sealing groove.

9. A composite building panel according to claim 8, wherein the intumescent seal is configured to activate at over 180degrees Celsius.

10. A composite building panel according to claim 8 or claim 9, wherein the seal has a 10 cross sectional thickness in the range of 1mm to 5mm and a cross sectional width in the range of 3mm to 12mm.

11. A composite building panel according to any one of claims 8 to 10, wherein the location and size of the seal is selected so that the seal reaches a temperature of 180 degrees Celsius within 50 minutes of a test according to AS 1530.4:2014.1512

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