GB2192211A

GB2192211A - Building block with insulation layer

Info

Publication number: GB2192211A
Application number: GB08714810A
Authority: GB
Inventors: Derek W Mcglashan; Michael R Crowley
Original assignee: CONCRETE MASONRY Ltd
Current assignee: CONCRETE MASONRY Ltd
Priority date: 1986-07-02
Filing date: 1987-06-24
Publication date: 1988-01-06
Also published as: GB8616105D0; GB8714810D0

Abstract

A building block has first and second spaced slab-like concrete members (10, 12) and a layer of polyurethane foam (14) between and bonded to the faces of the concrete members. The foam layer may be cast in situ or inserted as a preformed member. <IMAGE>

Description

SPECIFICATION Improvements in or relating to building blocks The present invention concerns improvements in or relating to building blocks. The invention is concerned particularly with concrete building blocks.

In the past to improve the insulation properties of blocks they have been formed with internal cavities and in an attempt to increase these insulating properties polystyrene foam has been placed in slab form or injected into the cavities.

The insulating properties of the polyurethane is at least 10 times greater than the insulating properties of the most insulative concrete presently used in the manufacture of blocks and it will be realised, therefore, that when a transverse cross-section through a block is considered those areas where there exists no polyurethane foam insulation, that is where concrete extends from the front to the back of the block, there exists a path of relatively.

high thermal conductivity which thereby reduces the overall insulation properties of the block.

It is an object of the present invention to obviate or mitigate these disadvantages without increasing the overall thickness of the block which, in turn, would give rise to constructional drawbacks when the block is used to build a structure.

According to the present invention there is provided a building block comprising first and second spaced concrete members and a layer of insulating material interposed between said members and bonded to the facing faces of the members.

Preferably the insulating material is polyurethane foam. The polyurethane foam may be a preformed member subsequently bonded to the facing faces of the concrete members but is preferably constructed in situ by injecting appropriate precursors of polyurethane foam into the space defined by two spaced apart concrete members and allowing foam to form under pressure between the members and bond to the facing faces thereof during curing.

Preferably the concrete members are spaced apart by a concrete bridge portion extending transversely of and between the facing faces of the members. The bridge portion may be situated mid-way between the ends of the block.

Further according to the present invention there is provided a method of manufacturing a building block comprising casting from concrete two spaced apart concrete members joined at their outer ends by bridge portions, allowing the concrete to set, injecting the precursors of a polyurethane foam into the cavity between the members, allowing the polyurethane foam to form and bond to the facing faces of the members and thereafter removing the said bridge portions.

Preferably the block of the method described above can be formed as a multiple length of a single block, said bridge portions being provided at the ends of said multiple block only, the multiple block being formed into appropriate blocks after the polyurethane foam has cured by cutting off said bridges and cutting the multiple length block into single blocks.

In an alternative method of manufacturing the product of the invention two concrete members in the form of substantially rectangular slabs are cast and allowed to set and are thereafter held at a fixed distance apart in a mould to which the precursors of a polyurethane foam are injected into the space between the members, the members being held in the mould until the foam has formed, adhered to the facing faces of the members and cured, thereby forming a block.

In a preferable form of the block of the present invention the polyurethane foam extends beyond the edges of at least two opposed edges of the block by a predetermined distance.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing, which shows a perspective view of one form of insulated concrete block.

A concrete block comprises two spaced apart substantially slab-shaped concrete members 10, 12 which are formed by casting in the normal way and allowed to set. They are then placed by any suitable means (which may be mechanised) in a mould such that they are spaced apart by a predetermined distance, conveniently with their outer faces 100mm apart.

The spaced apart members are then enclosed in the mould to which is supplied, that is into the cavity between the facing faces of the members, the precursors of a polyurethane foam. A measured amount of foam is pumped into the cavity in sufficient amount to completely fill the cavity after expansion and curing of the polyurethane foam. The block is retained in the mould for at least 3 minutes to allow the chemical reactions within the foam 14 to become complete so that the foam forms a relatively rigid central layer bonded to the facing faces of the concrete members to provide a rigid composite building block. The action of forming the polyurethane foam results in an increase in pressure in the mould and this pressure increase assists in the bonding of the foam to the concrete members.

The building block can then be removed from the mould and utilised in the fabrication of a structure in any conventional manner. As the block does not include the usual concrete end pieces extending between the members there is no thermal bridge between the outer and inner faces of the block so that compared with a normal block including a cavity and polyurethane foam its insulating properties are much increased.

In a first modification which is not illustrated in the drawings outer plates forming the mould have channels formed therein coinciding with the extremities of the cavity either on all sides of the block or on only the opposed end faces so that the finished block has a projecting nib of polyurethane foam which, when several blocks are placed in edge-toedge relationship abut. When a structure is built using mortar to fix blocks together the mortar does not extend from front to back of the joints between blocks but only from the outer face of the blockto the polyurethane nib thereby increasing the insulation value of the constructed wall.

In a further modification the block in plan is- H-shaped, that is there is a concrete bridging member (shown in dotted lines in the drawing) between the first and second members. This enables the two members 10 and 12 to be cast from concrete as a unit and may assist in the manufacturing process.

In a modified manufacturing process a block of length-greater than twice the length of a normal block is formed having bridging end pieces. After setting the block is fitted to a mould in the manner described above and polyurethane foam is injected into its cavity.

When the polyurethane mould has fully foamed and cured the bridging end portions are cut off the block and the block is halved to provide two building blocks of the type shown in the drawing.

Typically the dimensions of a block are, width 100mm, height 215mm, length 440mm.

To provide a building block of even greater insulation value the concrete may be formed utilising an Icelandic pumice aggregate. This results also in a block of lighter weight. Utilising such a concrete the mean equivalent thermal resistance of a block has been calculated to be of the order of 1.874m2 k/w.

The polyurethane foam referred to herein is a rigid foam, either fluorocarbon or water blown.

Claims

1. A building block comprising first and second spaced concrete members and a layer of insulating material interposed between said members and bonded to the facing faces of the members.

2. A building block as claimed in claim 1, in which the insulating material is polyurethane foam.

3. A building block as claimed in claim 2, in which the polyurethane foam is a pre-formed member subsequently bonded to the facing; faces of the concrete members.

4. A building block as claimed in claim 2, constructed in situ by injecting appropriate precursors of polyurethane foam into the space defined by two spaced apart concrete members and allowing foam to form under pressure between the members and bond to the facing faces thereof during curing.

5. A building block as claimed in any one of the preceding claims, in which the concrete members are spaced apart by a concrete bridge portion extending transversely of and between the facing faces of the members.

6. A building block as claimed in claim 5, in which the bridge portion is situated mid-way between the ends of the block.

7. A building block as claimed in any one of claims 2 to 6, in which the polyurethane foam extends beyond the edges of at least two opposed edges of the block by a predetermined distance.

8. A method of manufacturing a building block comprising casting from concrete two spaced apart concrete members joined at their outer ends by bridge portions, allowing the concrete to set, injecting the precursors of a polyurethane foam into the cavity between the members, allowing the polyurethane foam to Form and bond to the facing faces of the members and thereafter removing the said bridge portions.

9. A method as claimed in claim 8, in which a multiple length of a single block is formed, said bridge portions being provided at the ends of said multiple block only, the multiple block being formed into appropriate blocks after the polyurethane foam has cured by cutting off said bridges and cutting the multiple length block into single blocks.

10. A method of manufacturing a building block in which two concrete members in the form of substantially rectangular slabs are cast and allowed to set and are thereafter held at a fixed distance apart in a mould to which the precursors of a polyurethane foam are injected into the space between the members, the members being held in the mould until the foam has formed, adhered to the facing faces of the members and cured, thereby forming a block.

11. A building block substantially as hereinbefore described with reference to the accompanying drawing.

12. A method of manufacturing a building block, substantially as hereinbefore described with reference to the accompanying drawing.

13. Any novel subject matter or combination including novel subject matter disclosed in the foregoing specification or claims and/or shown in the drawings, whether or not within the scope of or relating to the same invention as any of the preceding claims.