Cavity former

Abstract

A cavity former 10 for use in forming a cavity in a concrete slab is disclosed. The cavity former comprises a support member which supports the weight of a person standing on the cavity former or of wet concrete bearing down on the array until the concrete has cured sufficiently to support itself. The array is reconfigurable between a compact state for stacking with other similarly configured arrays to facilitate transport and an expanded state to define a volume about which the wet concrete is poured. The cavity former 10 has a cover 34 which is engageable with the array to distribute the weight onto the array elements and prevent wet concrete flowing into the volume defined by the elements in the expanded state.

1 . A cavity former for use in forming a cavity in a concrete slab, said cavity former comprising: 
 (a) a support member for supporting a predetermined weight of a person standing on the member or of wet concrete bearing down on the member until the wet concrete has cured sufficiently to support itself; and    (b) cover means detachably engageable with the member for distributing said weight onto the member and preventing flow of said concrete into the member;    wherein said support member is stackable with at least one other similar support member for transport, the stacked support members collectively defining a volume less than the summed volume of the separate members.    
   
   
       2 . A cavity former according to  claim 1 , wherein the support member comprises an array of elements that is reconfigurable between a relatively more compact state for stacking with other similarly configured arrays to facilitate transport of the array and an expanded state for engagement with said cover means, the expanded state defining a volume about which the wet concrete may be poured, thereby creating a cavity in the resultant concrete slab.  
   
   
       3 . A cavity former according to  claim 2 , wherein said elements pivotally intersect with each other such that the array is foldable between the more compact and expanded states.  
   
   
       4 . A cavity former according to  claim 3 , wherein each element of said array is a panel including slots formed to interlock with corresponding slots of other elements in the array to provide elements which pivotally intersect with each other.  
   
   
       5 . A cavity former according to  claim 2 , wherein said elements, in the expanded state of the array, define a plurality of cells which are divisible from the cavity former to thereby alter the size and shape of the cavity former without affecting the integrity of the volume defined by the remaining cells.  
   
   
       6 . A cavity former according to  claim 2 , wherein said elements of the array are panels that are elongate horizontally, in situ, arranged with their planes parallel or orthogonal in the expanded state.  
   
   
       7 . A cavity former according to  claim 2 , wherein the cavity former further includes means for locating the cover means in engagement with the array.  
   
   
       8 . A cavity former according to  claim 7 , wherein the locating means comprises a rim defined by elements forming the periphery of the cavity former such that the cover means locates within the rim and engages the peripheral elements.  
   
   
       9 . A cavity former according to  claim 1 , wherein the support member is nestable with at least one other similar support member to provide said stackability.  
   
   
       10 . A cavity former according to  claim 9 , wherein the support member comprise a top surface complementary to an underside surface of the member to provide said nestability.  
   
   
       11 . A cavity former according to  claim 10 , wherein the support member includes open channels for receiving at lest part of another support member to enable stacking of the members.  
   
   
       12 . A cavity former according to any one of  claim 11 , wherein a lattice arrangement is provided by an integrally formed matrix of cell walls, each cell wall having a V-shape in cross-section, said matrix defining a plurality of cells.  
   
   
       13 . A cavity former according to  claim 12 , wherein said matrix defining a plurality of cells is divisible to alter the size and shape of the support member without affecting the integrity of the volume defined by the remaining cells.  
   
   
       14 . A cavity former according to  claim 13 , wherein each cell has a floor formed on the same side of the support member as the channels to provide the support member with enhanced structural strength.  
   
   
       15 . A cavity former according to  claim 14 , wherein the support member comprises paper pulp.  
   
   
       16 . A cavity former according to  claim 1 , wherein the cover means is a panel.  
   
   
       17 . A cavity former according to  claim 1 , wherein said cover means is reconfigurable between a relatively more compact state, to facilitate transport of the cover means, and an expanded state for engagement with the support member.  
   
   
       18 . A cavity former according to  claim 17 , wherein the cover means, is in one state, a blank that is foldable to form a housing, for receiving said support member having an integrally formed lid engageable with the support member.  
   
   
       19 . A cavity former according to  claim 18 , wherein the cavity former further includes means for locating the cover in engagement with the support member.  
   
   
       20 . A cavity former according to  claim 19 , wherein the locating means comprises a hinge linking the lid to the housing.  
   
   
       21 . A cavity former according to  claim 20 , wherein means is provided for retaining the cover means in engagement with the support member.  
   
   
       22 . A cavity former according to  claim 21 , wherein the retaining means comprises walls depending from the lid, which walls frictionally engage with the housing when the lid is engaged with the support member.  
   
   
       23 . A cavity former according to  claim 2 , wherein the elements are formed as concertinas linked at their respective ends by common end walls.  
   
   
       24 . A cavity former according to  claim 23 , wherein the cavity former further includes means for locating the cover means in engagement with the array.  
   
   
       25 . A cavity former according to  claim 24 , wherein the locating means is provided by rims defined by the end walls having a height greater than the length of the elements.  
   
   
       26 . A cavity former according to  claim 23 , wherein means is provided for retaining the cover means in engagement with the array.  
   
   
       27 . A cavity former according to  claim 26 , wherein the retaining means is provided by a pair of depending side walls attached to the cover means, which side walls frictionally engage the respective end walls to retain the cover means in engagement with the array of elements.  
   
   
       28 . A cavity former according to  claim 23 , wherein the elements are formed to bias the cavity former into the more compact state, thereby enhancing frictional engagement of the side walls with the end walls.  
   
   
       29 . A cavity former according to  claim 2 , wherein the elements include substantially parallel rigid walls linked at their respective ends by flexible walls.  
   
   
       30 . A cavity former according to  claim 29 , wherein the cavity former further includes means for locating the cover means in engagement with the array.  
   
   
       31 . A cavity former according to  claim 30 , wherein the locating means comprises rims defined by common end walls linked to the flexible walls, which common end walls have a height greater than the elements.  
   
   
       32 . A cavity former according to  claim 31 , wherein means is provided for retaining the cover means in engagement with the array.  
   
   
       33 . A cavity former according to  claim 32 , wherein the retaining means is provided by a pair of depending side walls attached to the cover means, which side walls frictionally engage the respective end walls to retain the cover means in engagement with the array of elements.  
   
   
       34 . A cavity former according to  claim 1 , wherein the cavity former is capable of supporting up to 50 kPa from the weight of a person or of the wet concrete poured to form the slab.  
   
   
       35 . cavity former according to  claim 1 , wherein the cavity former is capable of supporting said predetermined weight for up to 3 hours.  
   
   
       36 . A cavity former for use in forming a cavity in a concrete slab, said cavity former comprising a plurality of linked modules, each module comprising: 
 (a) elements for supporting a predetermined weight of a person standing on the elements or of wet concrete bearing down on the elements until the wet concrete has cured sufficiently to support itself;    (b) cover means integrally formed with the elements for distributing said weight onto the elements and preventing the flow of wet concrete between the elements; and    wherein each module is reconfigurable between a relatively more compact state for stacking with other similarly configured modules to facilitate transport of the module and an expanded state for linking to at least one other module, the linked modules in the expanded state defining a volume about which the wet concrete may be poured thereby creating a cavity in the resultant concrete slab.    
   
   
       37 . A cavity former according to  claim 36 , wherein each module, in the compact state, comprises a blank foldable to form an upturned tray.  
   
   
       38 . A cavity former according to  claim 36 , wherein each module includes means for retaining the module in the expanded state.  
   
   
       39 . cavity former according to  claim 38 , wherein the retaining means comprises tabs formed on the elements and slots for receiving the tabs.  
   
   
       40 . A cavity former according to  claim 36 , wherein the cavity former is made of a degradable material.  
   
   
       41 . A cavity former according to  claim 40 , wherein the cavity former is made of cardboard or fibreboard.  
   
   
       42 . A cavity former according to  claim 41 , wherein the cardboard or fibreboard has a coating which slows the diffusion of moisture into the cardboard or fibreboard.  
   
   
       43 . A cavity former according to  claim 36 , wherein the cavity former is capable of supporting up to 50 kPa from the weight of a person or of the wet concrete poured to form the slab.  
   
   
       44 . cavity former according to  claim 36 , wherein the cavity former is capable of supporting said predetermined weight for up to 3 hours.