AU2003101087A4 - Construction panel - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor: Address for Service: Invention Title: Leander Constructions Pty Ltd Sam Salerno DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, Victoria 3000.

"Construction panel" Details of Associated Provisional Application: No: PS0927/02 6 March 2002 The following statement is a full description of this invention, including the best method of performing it known to us: P:,OPER\MKR\SPECl\pand-p doc-06/03/03 -1- CONSTRUCTION PANEL FIELD OF THE INVENTION The present invention relates to construction panels comprising a foam core contained within glass reinforced concrete as well as to processes for their production.

BACKGROUND OF THE INVENTION Foam concrete such as for example CelluconTM (available in Australia from Romaroda Chemicals Pty Ltd, 11 Mason Drive, Braeside, Vic, 3195) is a well known material useful in a diverse range of building applications. This material is especially advantageous for use in building construction because it is fire resistant, lightweight, impact resistant, nontoxic and exhibits high thermal and acoustic insulation. Foam concrete is produced by entrapping a multitude of small air bubbles in a cement based mixture. This is achieved by injecting a foaming agent into the cement mixture via an aerator. It is possible to produce foam concrete ranging from 300 kg to 1600 kg per cubic metre, depending upon the extent of air entrapment.

Although foam concrete has been used up to date in applications such as flooring, interspace filling, acoustic/thermal insulation, partition walls and the like, in order for it to be used in load bearing applications it has been necessary for metal reinforcement to be incorporated. The inclusion of such metal reinforcement means that the major advantage of use of foam concrete relative to standard concrete, namely its light weight, is negated.

Numerous other attempts have been made to develop load bearing building construction materials that are at the same time light weight and preferably also offer favourable characteristics of heat and acoustic insulation, fire resistance and resistance to corrosion or degradation by insects or other biological material. In large part, the search for suitable light weight load bearing building construction materials of this type has to date been fruitless. It is therefore with this background in mind that the present invention has been conceived.

P:\OPER LKR SPECI\panc-ccup.dmc.06/03/03 -2- SUMMARY OF THE INVENTION According to one embodiment of the present invention there is provided a construction panel comprising a foam core contained within glass reinforced concrete.

Preferably the construction panel is a load bearing construction panel and preferably the foam core is a foamed concrete or foamed polymer material. In the case of a foamed polymer material the material may comprise polystyrene, polyvinyl chloride, polyurethane and/or polyethylene.

In a preferred embodiment of the invention the glass reinforced concrete comprises sand, cement and fibreglass. Preferably the fibreglass is in the form of filament, chopped fibre or mesh. Most preferably the fibreglass is in the form of chopped fibre mixed through the glass reinforced concrete.

In another embodiment of the invention the glass reinforced concrete further comprises one or more of an anti-crack agent, mortar plasticiser and lime.

In another embodiment of the invention there is provided a method of producing a construction panel comprising the steps of: providing a mould of desired panel dimensions; pouring a layer of glass reinforced concrete mix into said mould; adding foam core material to said mould; adding further glass reinforced concrete mix to fill said mould to desired level and thereby encapsulate said foam core material; leaving cast panel produced in step in mould for a period sufficient to allow setting of concrete before removing cast panel from said mould; allowing cast panel removed from said mould to cure for a suitable period.

I P:\OPER\MKRSPECJ\200320873-1 pa dmcnll. do- 23/I I/2007 -3z Preferably the period sufficient to allow setting is between about 12 hours and about 48 IND hours. Particularly preferably the period sufficient to allow setting is about 24 hours.

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In another preferred embodiment of the invention the suitable period for curing is between 00 5 about 10 days and about 60 days. Preferably the suitable period for curing is about 28 days.

DETAILED DESCRIPTION OF THE INVENTION 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.

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 in the field of endeavour to which this specification relates.

In its broadest aspect the present invention relates to a construction panel comprising a foam core of foamed concrete or foamed polymer material contained within glass reinforced concrete. Although it is preferable for the construction panel to be pre-cast and cured for subsequent use in a building application, it is possible for the construction panels according to the invention to be manufactured on site or in situ.

A particular advantage of panels according to the present invention is that although they are relatively lightweight they can be produced to exhibit sufficient load bearing capacity to be used in a structural, rather than purely aesthetic manner. Due to the lightweight nature of the panels according to the invention they can readily be lifted and manoeuvred into the appropriate position manually without the need for cranes or other mechanised P kOPERUMMR SPECP20032OI473.I p do.lh31,20)7 -3Az lifting devices. The panels according to the invention may also possess favourable N characteristics of thermal and acoustic insulation, fire and impact resistance and resistance to corrosion and degradation by biological materials such as insects. The lightweight nature of the panels according to the invention and their load bearing capacity gives rise to 0 a simplicity of construction of structures comprising them, which may result in reduced construction time and cost relative to constructions using conventional material.

P:\OPER\MKR\SPECI\p.a, o.lp.d.oc-O6'O3I -4- While the panels according to the invention include in their broadest aspect a foam core encapsulated by glass reinforced concrete, it is possible for other additional components to be present. For example additional reinforcement, preferably of a lightweight type, may be incorporated within or around the foam core material and the foam core and/or the external surfaces of the construction panel may include conventional laminates, coatings or cladding material. Particularly in relation to the external surfaces of the construction panel conventional coatings, claddings or laminates may be added for aesthetic or functional purposes. Another benefit of the panels according to the present invention is that they may be secured one to another or to other building components by the use of conventional means such as bolts, screws, nails, brackets or by virtue of an interlocking configuration.

In one embodiment of the invention the panels may be provided with tongue and groove edges which enable interlocking and draught and moisture sealing between adjacent panels within a building structure.

In one embodiment of the invention where the construction panel is configured to be used as a partition or load bearing wall the panel is recessed at its base edge to receive a foot that may be attached to a base surface such as a floor, joist, post, beam or the like. It may be appropriate as a means of linking panels together which are located in a planar fashion for a U-shaped bracket to be placed at a base or top surface of the panels overlapping the junction therebetween. Brackets of this type may be angled, such as for example to form a right angle where the panels are together intended to form a corner. The panels of the invention may also be adapted by the presence of appropriately located holes for fixing means such as bolts, screws or the like, to be fixed to posts. By virtue of locking tongue and groove type arrangements the panels of the invention can be configured to lockably fit together, thus allowing them to be essentially free standing in construction, or at least minimising the amount of supporting infrastructure required.

As indicated above, the construction panels according to the present invention include a core of foam material. This foam material is preferably of relatively light weight, compatible with the glass reinforced concrete and is relatively stable in the sense that it P:\OPERW1KR\SPECnpo .l-p.doc.0610303 will not readily degrade. Examples of materials which may be used as the foam core include foamed concrete, such as Cellucon T M and foamed polymer materials such as polystyrene, polyvinyl chloride, polyurethane and/or polyethylene. For example, these polymer materials may be present in the form of copolymers involving one or more of these or other foamed polymers. The lightweight nature of the foamed core material will derive from it having been produced in a manner which results in the inclusion of gas voids or cells, for example voids or cells containing air, oxygen, carbon dioxide or nitrogen. The production of foams of this type is well understood in the art.

The glass reinforced concrete material used to surround the foam core will be produced from a glass reinforced cement mix, the key ingredients of which are cement, sand and fibreglass. Cement and sand of various grades as used in the construction industry, and as readily commercially available, can be adopted in the glass reinforced concrete mix. It is also possible to use fibreglass of various types and configuration. For example, the fibreglass may take the form of filament, fibreglass mesh or chopped strands. Preferably the fibreglass takes the form of chopped strands. The fibres, filaments or strands may be of varying length and diameter. In a preferred embodiment of the invention the fibreglass takes the form of Cem-FIL T M fibreglass such as is available from Resin Fibreglass Sales, Lothian Street, North Melbourne, Victoria 3051, Australia. In the case of the use of chopped strands, a preferred product is Cem-FIL F60/2 with a strand length of either 12mm or 24mm, which is specified to have 102 filaments per strand each of which is in diameter. It is to be understood that mention of this specific strand type is by way of example only and is not intended to be limiting upon the scope of the invention.

Within the reinforced concrete mix it may also be appropriate to incorporate additional components such as anti-crack agent, mortar plasticiser, fire suppressing agent, acoustic insulation, heat insulation, lime, crushed rock, rubber pellets, crumb or fibre, colouring agent or other materials conventionally included in cement mix. Naturally the cement mix will also include solvent, preferably water, to enable the formation of a slurry that will harden upon evaporation of the solvent.

P:\OPER\MKR\SPECIpan ©.-cup.do-06/03/03 -6- In producing the construction panels according to the present invention it is necessary to provide a mould or boxing that defines the desired configuration of the panel. The mould may for example be manufactured from wood, metal, plastics or fibreglass material, although it is preferably produced from wood or metal. The boxing will have dimensions/configuration such as to result in the panel produced therein having the desired dimensions/configuration and optionally having openings as necessary for services, having extruded sections or a configuration allowing interlocking with adjacent panels. The mould may include holes or openings for joining of panels, although it is also possible for such holes or openings to be created later, for example by drilling of either the moulded uncured panel or the cured product.

To produce the panels a layer of the cement mix will be introduced into the mould and the foam core material is added and is then covered by further cement mix such that the foam core is encapsulated within the cement mix and located therewithin, having the desired thickness of cement mix surrounding it. After leaving the cast panel within the mould for a period sufficient to allow setting of the concrete the cast panel is removed from the mould and then allowed to cure for a suitable time period. For example, the panel may be allowed to set within the mould for a period of between about 12 hours and about 48 hours, more preferably between about 18 hours and about 30 hours, and particularly preferably about 24 hours, before removal of the cast panel. It will of course be understood by persons skilled in the art that the amount of time during which the cast panel must be left within the mould will be dependent upon the ambient temperature and humidity conditions. It may also be possible to speed the period before the cast panel is removed from the mould by artificial means such as by applying heat to the panel within the mould.

This may be in the form of application of a jet of warm air or by placing the panel within an oven, kiln or the like. Particularly in the case of situations where the construction panels are to be used for load bearing functions it is important that the cast panels are allowed a sufficient time to cure and thereby harden prior to being exposed to a load. This can be achieved simply by leaving the panel at rest for a period of between about 10 days and about 60 days, preferably between about 20 days and about 40 days, most preferably for about 28 days. Once again, however, the period allowed for curing will depend upon P:\OPER\IKR\SPECl\panclpdoc-6/03/03 -7the ambient conditions of temperature and humidity and ultimately the appropriate period allowed can be determined by assessing the time period over which the required hardness will develop upon exposure to given conditions.

In a preferred embodiment of the invention the glass reinforced concrete mix comprises between about 30% to about 60% by weight of sand, between about 25% to about 45% by weight of cement, between about 15% to about 25% by weight of water and between about to about 2% by weight of chopped glass fibre. The mix may also comprise for example up to about 0.05% by weight of anti-crack agent, up to about 0.25% by weight of mortar plasticiser and/or up to about 2% by weight of lime.

The panels according to the present invention can be produced in an unlimited range of dimensions. For example, however, panels according to the present invention have been produced in sizes of 84 x 500 x 2685mm and 73 x 600 x 2395mm. These dimensions are mentioned by way of example only. It is also possible to vary considerably the relative amounts of foam core and glass reinforced concrete present within the panels. By way of example only, it is possible for the foam core to comprise from between about 20% to about 95% of the cross sectional width of the panel, depending upon the use for which it is intended. More preferably, the foam material will comprise between about 40% to about 80% of cross sectional width, still more preferably between about 60% to about 80% and most preferably about 75% of the cross sectional width of the panel. Therefore, in the case of a panel approximately 85mm in width the panel may comprise an internal layer of between about 30mm to about 70mm of foam material and two external layers of glass reinforced concrete each of between about 7.5 to about 27.5mm in width. More preferably, however, a panel of approximately 85mm in width may comprise a central foam core of approximately 65mm in width and two external layers of glass reinforced concrete each of approximately 10mm in width.

The construction panels according to the present invention will now be further described with reference to the following non-limiting example.

P:0PERVAKR\SPEC\pnIa1-rp dw06/03/03 -8- EXAMPLE 1 Testing and evaluation of foam core glass reinforced concrete panel 1. AIM OF TESTING The aim of the testing and evaluation program was to estimate design capacities for limit states design and allowable loads for working stress design for 2 sizes of foam core Glass Fibre Reinforced Cement (GFRC) panels. This was to be carried out for axial compression and bending loads for the 84 x 500 x 2685mm long panels and for bending loads only for a 73 x 600 x 2395 mm long panel.

2. TEST SPECIMENS The test specimens consisted of glass fibre reinforced concrete (GFRC) panels with a styrene foam core. The wall thicknesses on the faces of the GFRC was approximately 11 to 13mm. The wall thicknesses inspected around the top, bottom and sides varied between about 10 and about The panels were produced from a cement mix comprising the following components: 38kg sand 29kg cement water 0.025kg HD anti-crack 0.65kg sem-fill chopped glass fibre (24mm length) 0.015kg mortar plasticiser 1.25kg lime.

The mixture was mixed thoroughly to form a slurry. A layer of the slurry of the desired GFRC wall thickness was carefully added to the mould to avoid the presence of air bubbles and the appropriate size of styrene foam core material was placed in a central position P;'%OPER\M KR\SPECl\pncl -cp.dol-06/03/03 -9within the mould. The styrene foam core material was then covered by further mix to fill the mould and the exposed surface was finished by hand.

The cast panels were left on racks in a covered but well ventilated area, exposed to ambient temperature for a period of approximately 24 hours before being carefully removed from the mould. The cast panels were then stored on racks under the same conditions for approximately 28 days to cure and harden.

3. TEST PROCEDURE 3.1 Axial (compression) load test for 84 x 500 x 2685mm long panel The axial (compression) load test on the 84 x 500 x 2685mm long panel was conducted vertically with a uniform distributed line load (500mm long) applied to the top of the panel, eccentric to the centre of thickness of the panel by approximately 21mm. The base of the panel had a uniformly distributed load without any eccentricity. The load was applied at a rate of approximately 10 kN/min until the first indication of bearing failure was recorded. That load was taken to be the ultimate test load. The loading was continued at the same rate until a maximum load was reached. This was to give an indication of reserve capacity post initial bearing failure.

3.2 Bending test for 84 x 500 x 2685 mm long panel The bending test on the 84 x 500 x 2685mm long panel was conducted as a 4 point bending test was applied loads at 1/3 points of the span. The span was 2600mm. The load was applied at a rate of approximately 1 kN/min until the panel fractured. The maximum load was taken to be the ultimate test load. Displacement was also recorded.

3.3 Bending test for 73 x 600 x 2395mm long panel The bending test on the 73 x 600 x 2395mm long panel was conducted as a 4 point P:\OPEkMWKRSPECI\patd-p.doc-6/3/03 bending test with applied loads at 1/3 points of the span. The span was 2300mm. The load was applied at a rate of approximately 1 kN/min until the panel fractured. The maximum load was taken to be the ultimate test load. Displacement was also recorded.

4. RESULTS AND DISCUSSION 4.1 Axial (compression) load test for 84 x 500 x 2685 mm long panel This panel was tested 29 days after casting. The ultimate test load for panel was 100.4 kN.

The maximum load attained in the test was 128.4 kN. The first point of failure was a bearing failure on the loaded side of the top of the panel. The second point of failure was a very localised buckling at one end of the base of the panel. The third point of failure was the local collapse of the top end of the panel on the loaded side. A line of fracture on the top end about 20 mm from the face furthest from the line load was consistent with a triangular load distribution with no load near the face furthest from the line load.

The difference between the ultimate load and the maximum load indicates a small degree of post failure reserve capacity against collapse. See load against time plot shown in Fig 1 and refer to Figs 2 and 3 for load displacement plots.

The evaluation of the above results to determine a design capacity for use in limit states design and an allowable load for use in working stress design was based on methods inferred in a range of Australian standards for structures used for a variety of building materials.

P:\OPER\WKRSPECi~ppncI-lp dom-06/O3/03 -11- Design capacity for axial (compression) load for use in limit states strength design: Mean Coefficient of variation of test Coefficient of variation of construction Coefficient of variation of material Sampling factor x=100.4 kN Vtest 0.10 (estimate) Vcon, 0.050 (estimate) Vmat 0.150 (estimate) Vtotal 10.10 2 +0.052 +0.152 0.187 2.07 from AS 4100 Supplement 1 Table C17.5.2 for V=18.7% and 1 unit tested.

S 100.4 2.07 2.07 Design capacity 48.5 kN Allowable load for axial (compression) load for use in working stress design: Using the design capacity established above Allowable load Po 48.5 PAlow 32.3 kN The above design capacity and allowable load are for the loading conditions and eccentricities described in the test set up. The design capacity and allowable load are based on the assumption that the coefficients of variation for test, construction and materials are as indicated above.

4.2 Bending test for 84 x 500 x 2685mm long panel This panel was tested 33 days after casting. The ultimate test bending moment for the panel was 2.28 kNm. The load deformation plot for the test shown in Fig. 2 reveals linear behaviour up to the point of failure with no ductility after the maximum load was reached.

P:\OPER\MKR\SPECI\panc-ap.doc-06/03/03 -12- Design capacity for bending for use in limit states strength design: Mean Coefficient of variation of test x =2.28 kNm Vtest= 0.15 (estimate) Assuming coefficients of variation for construction and material as for axial load capacity above.

Vtotai /0.152 +0.052 +0.152 0.218 Sampling factor 2.40 from AS 4100 Supplement 1 Table C17.5.2 for V=21.8% and 1 unit tested.

2.28 P 2.40 0.95 kN Design capacity Allowable load for bending- for use in working stress design: Using the design capacity established above Allowable load 0.95 PAIlow 0.63 kNm The above design capacity and allowable load are for the loading conditions described in the test set up. The design capacity and allowable load are based on the assumption that the coefficients of variation for test, construction and materials are as indicated above.

P:\OPER\MKR\SPECI'\pandc.apdoc0603/03 13 4.3 Bending test for 73 x 600 x 2395mm long panel This panel was tested 35 days after casting. The ultimate test bending moment for the panel was 1.64 kNm. The load deformation plot for the test shown in Fig. 3 reveals linear behaviour up to the point of failure with no ductility after the maximum load was reached.

Design capacity for bending for use in limit states strength design: Mean Coefficient of variation of test x=1.64 kNm Vtes,= 0.15 (estimate) Assuming coefficients of variation for test, construction and material as for axial load capacity above.

Vtoal 40.152 +0.052 +0.152 0.218 Sampling factor 2.40 from AS 4100 Supplement 1 Table C17.5.2 for V=21.8% and 1 unit tested.

1.64 2.40 0.68 kN Design capacity Allowable load for bending- for use in working stress design: Using the design capacity established above Allowable load 0.65 PAIlow 0.45 kNm P:\OPER\ KR\SPEC\panclkup.dc-06/03/03 14- The above design capacity and allowable load are for the loading conditions described in the test set up. The design capacity and allowable load are based on the assumption that the coefficients of variation for test, construction and materials are as indicated above.

5. RESULTS AND DISCUSSION The design capacity for axial (compression) load for the 84 x 500 x 2685mm long panel for use in limit states design is 48.5 kN. The equivalent allowable load for use in working stress design is 32.3 kN. These values are based on the assumption that the coefficients of variation for test, construction and materials are as indicated in Section 4 above.

The design capacity for bending for the 84 x 500 x 2685mm long panel for use in limit states design is 0.95 kNm. The equivalent allowable load for use in working stress design is 0.63 kNm. These values are based on the assumption that the coefficients of variation for test, construction and materials are as indicated in Section 4 above.

The design capacity for bending for the 73 x 600 x 2395mm long panel for use in limit states design is 0.68 kNm. The equivalent allowable load for use in working stress design is 0.45 kNm. These values are based on the assumption that the coefficients of variation for test, construction and materials are as indicated in Section 4 above.

6. REFERENCE Standards Australia. Steel structures Commentary. Australian Standard ASA 4100 Suppl- 1990.

It is to be understood that the present invention has been described by way of example only and that modifications or alterations to the invention as described are also considered to fall within the scope and spirit of the invention as defined within the appended claims.

Claims (5)

1. A construction panel comprising a foam core of foamed concrete or foamed polymer material contained within glass reinforced concrete. 00

2. The construction panel according to claim 1 wherein said foamed polymer material comprises polystyrene, polyvinyl chloride, polyurethane and/or polyethylene.

3. The construction panel according to either claim 1 or claim 2 wherein said glass reinforced concrete comprises sand, cement and fibreglass.

4. The construction panel according to claim 3 wherein said fibreglass is in the form of chopped fibre mixed through said glass reinforced concrete.

5. A method of producing a construction panel comprising the steps of: providing a mould of desired panel dimensions; pouring a layer of glass reinforced cement mix into said mould; adding foam core material of foamed concrete or foamed polymer material to said mould; adding further glass reinforced concrete mix to fill said mould to desired level and thereby encapsulate said foam core material; leaving cast panel produced in step in mould for a period sufficient to allow setting of concrete before removing cast panel from said mould; allowing cast panel removed from said mould to cure for a suitable period.