GB1598916A

GB1598916A - Building block a method of making same and a mould for performing the method

Info

Publication number: GB1598916A
Application number: GB47422/77A
Authority: GB
Original assignee: EBERLIN M
Current assignee: EBERLIN M
Priority date: 1976-11-15
Filing date: 1977-11-15
Publication date: 1981-09-23
Also published as: BE860797A; ES464375A1; ATA811977A; CH611671A5; DE2734513A1; FR2370836A1; FR2370836B1; IT1091048B

Description

(54) BUILDING BLOCK, A METHOD OF MAKING SAME AND A MOULD FOR PERFORMING THE METHOD (71) I, MADELEINE EBERLIN, a Swiss Citizen located at 19, Chemin Adrien Jeandin, 1226 Thonex (GE, Switzerland), do hereby declare this invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a building block for making walls or partitions which are thermally insulating, and also to a method of manufacturing such a building block and a mould for performing the method.

A great number of types of thermally insulating bricks or building blocks are known.

In French Patent No. 2,188,016 there is described a thermally insulating brick having vertical channels in which an insulating material in the form of a plate is introduced, the channels being separated by ribs connecting the internal and external portions of the brick.

The ribs or walls forming the vertical channels act as a cold bridge, such that the heat can flow between the internal surface (hot) and the external surface (cold) of a wall built with the bricks described in French Patent No. 2,188,016. Moreover, the fact that the insulating plates are introduced into the channels of the bricks without being connected to the walls forming these channels allows water vapour contained in the air between the insulating plates and the adjacent surfaces of the channels to condense when the temperature drops, which causes dampness.

Walls or partitions made with the bricks described in German Patent Application (DOS) No. 2440466 have the same disadvantages.

An object of the invention is to provide a building block without a cold bridge between its two lateral parts and in which condensation phenomena are minimised.

According to a first aspect of the present invention, there is provided a building block for making walls or partitions, comprising two layers of building material having opposed faces which are separated by a layer of insulating material, the periphery of the insulating layer having recessed and/or projecting portions adapted to engage corresponding portions of the insulating layer of another building block or a locating member located between said blocks, the insulating layer being formed from an acoustically and thermally insulating expanded material and being bonded to said layers of building material solely by penetration of the expanded material into pores or recesses in said opposed faces thereof, such that the three layers form a monolithic structure.

In one particular construction of building block, the peripheries of the three layers form a first pair of adjacent edge surfaces in which the periphery of the insulating layer has projecting portions, and a second pair of adjacent edge surfaces in which the periphery of the insulating layer has recessed portions. In another construction, one of the layers of building material is L-shaped and extends along two adjacent side faces of the other layer of building material, and the insulating layer is also L-shaped and its periphery has recessed portions on all faces of the building block where it is visible.

Each recessed portion of the insulating layer can be in the form of a groove having oblique lateral walls, and each projecting portion can similarly be in the form of a ridge having oblique lateral walls.

According to a second aspect of the present invention, there is provided a building structure incorporating on; or more building blocks of the invention.

According to a third aspect of the present invention, there is provided a method of manufacturing a building block according to said first aspect of the invention comprising placing two layers of building material in a mould such that opposed faces thereof are separated by a space, the mould defining recessed and/or projecting portions on the periphery of said space; closing the mould, and injecting an acoustically and thermally insulating expanded material into the space between said layers of building material such that the expanded material penetrates into pores or recesses in said opposed faces and thereby bonds the layers into a monolithic structure.

According to a fourth aspect of the present invention, there is provided a mould for performing the method defined in the last preceding paragraph, comprising a plurality of mould portions, at least some of which are movable, which are arranged to enclose the periphery of the two layers of building material separated by a space and which define the recessed and/or projecting portions on the periphery of said space, and means for injecting the expanded material into said space between the two layers of building materials.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a rightangle assembly made from building blocks of the invention, the assembly forming the corner of a wall, Figure 2 is a section through the assembly of blocks along the line Il-Il of Figure 1, Figure 3 is a section through the assembly of blocks along the line Ill-Ill of Figure 1, Figure 4 is a perspective view of part of a wall made with the building blocks shown in Figure 1, the wall being surmounted by a concrete slab, Figure 5 is a view from above of a part arranged to close off the sides of the concrete slab of Figure 4, Figure 6 is a section along the line VI-VI of Figure 5, Figure 7 is a view from above showing a right-angle assembly of two parts as shown in Figure 5, Figures 8 and 9 show locating or additional joint members intended to be used to assemble building blocks in particular cases, Figure 10 is a section through a concrete slab cast on a load bearing wall made by means of the building blocks at a location surmounting a window, Figure 11 is a side view of a mould according to the invention intended for the.

manufacture of building blocks, and Figure 12 is a section through the mould along the line XII-XII of Figure 11.

Referring to Figure 1, this shows an assembly forming a part of the comer of a wall and including two types of building block, namely angle or end blocks 1, 2, 3 and standard blocks 4, 5. The standard blocks are those which are used the most and are utilised for building any wall or partition. The angle or end blocks are designed to be placed solely at locations where the wall or partition being built ends, for example at the edges of doors or windows where a right-angle is formed. The angle or end blocks 1, 2 and 3 must, in accordance with the normal practice of masons for centuries when building walls by means of bricks or stones of the same size, be capable of being placed so as to extend alternatively in two directions which are mutually perpendicular, as shown in Figure 1 for the blocks 2 and 3 for example.Therefore, the end blocks 1, 2 and 3 are made so as to be capable of being assembled in the two positions indicated by the blocks 2 and 3. By contrast, the standard blocks 4 and 5 will always be located in the same position, and as a result are made slightly differently from the end blocks 1, 2 and 3.

Each of the blocks 1 to 5 comprise generally two layers 6 and 7 of building material having opposed faces 9 and 10 (Figure 2) which are separated by a layer 8 of insulating material, such that the three layers 6, 7 and 8 form a sandwich. In the illustrated arrangement, the layer 6 constitutes a facing element whereas the layer 7 forms a load-bearing element which is thicker than the facing element. The layers 6 and 7 can be made from any material used in building, particularly cement, concrete, expanded clay or brick. As a general rule, layer 6 forming the facing element will be made from any material which lends itself to the decoration of a facade, for example cement, bricks or ETERNIT (registered trade mark) and may also undergo rough-casting.

The layer 7 forming the load-bearing element will generally be made from concrete, expanded clay or brick.

It should be pointed out that the assembly of Figure 1 shows a load-bearing wall, for example, the external wall of a building. For this reason, the load-bearing element 7 of each building block is wider than the facing element 6. It is, however, possible to provide an alternative (not shown) in which the element 6 has exactly the same dimensions as the element 7. Such a building block, made from identical elements 6 and 7 sandwiched with a layer of insulating material could, for example, be used to make partitions in a building in which the room temperature must be very different, for example the partitions forming a cold room.

The acoustically and thermally insulating layer 8 will in general be formed from a rigid and expanded insulating material, for example, polyurethane foam or agglomerated polystyrene such as sagex or STYROPOR (registered trade mark). Very good results have been obtained with a fire-proofed non ageing polyurethane foam having a closed cell structure. The two components of the polyurethane foam are injected into a mould into which the layers 6 and 7 have previously been placed. This operation will be described in detail later with reference to Figures 11 and 12. It should nevertheless be noted that the polyurethane foam must adhere to the opposed surfaces 9 and 10 of the layers 6 and 7 so that the three layers 6, 7 and 8 form a monolithic structure.For this reason, it is essential that the bonding between the surfaces 9 and 10 of the layers 6 and 7 and the foam 8 should produce an interpenetration of the foam into the layers 6 and 7. The surfaces 9 and 10 of the layers 6 and 7 must therefore be porous or rough to permit such bonding. The materials mentioned above, such as cement, expanded clay and brick, all have this property.

As can be seen in Figure 1, in the angle or end blocks 1, 2 and 3 the layer 6 is Lshaped and extends along two adjacent side faces of the layer 7, the layer 6 providing two external facing surfaces 12 and 13 at rightangles to one another. The layer 6 can be formed as a single piece or in two parts as indicated by broken line 11. The insulating layer 8 is also of L-shape, and its periphery has recessed portions 14 on all faces of the building block where it is visible, each of the recessed portions 14 being in the form of a groove having a flat bottom 15, oblique lateral walls 16 and shoulders 18 and 19 which lie flush with the layers 6 and 7 respectively. The recessed portions 14 are adapted to engage correspondingly shaped projections on the standard blocks 4 and 5 or on a locating member 17 which will be described in detail later.It will be appreciated that all of the external faces of the angle or end blocks are flat, with the exception of the recessed portions 14. More particularly, the upper surfaces of the layers 6 and 7 and the shoulders 18 and 19 are situated in the same plane, with only the recessed portion 14 passing within the block.

In each of the standard blocks 4 and 5, the peripheries of the three layers 6, 7 and 8 form a lower edge surface 20 (see Figure 2) and a lateral edge surface 21 (see Figure 1) having similar recessed portions 14 to those of the end blocks 1, 2 and 3. The recessed portions are thus in the form of grooves having oblique lateral side walls, the grooves having exactly the same dimensions as those of the end blocks. The peripheries of the three layers 6, 7 and 8 also form an upper edge surface 22 opposed to the lower edge surface 20 and a further lateral edge surface (not visible) opposed to the lateral edge surface 21 which have projecting portions 23 of complementary form to the recessed portions 14. Thus, each projecting portion 23 is in the form of a ridge having oblique lateral side walls 24 and corresponding in dimension to the grooves 15.

Each projecting portion 23 has respective shoulders 25 of substantially square section at the bases of the lateral walls 24. As can be seen to advantage in Figure 2 and 3, the shoulders 25 stand proud of the adjacent surfaces of the layers 6 and 7 by an amount corresponding substantially to the thickness of a layer 26 of cement which is placed on the blocks during their assembly into a wall.

In an alternative embodiment (not shown), the shoulders 25 are omitted and the projecting portions 23 have oblique lateral walls 24 which end respectively at the internal edges of the upper surfaces of the layers 6 and 7.

Since the standard blocks 4 and 5 have a first pair of adjacent edge surfaces. (i.e. the lower edge surface 20 and the lateral edge surface 21 provided with recessed portions 14 and a second pair of adjacent edge surfaces (i.e. the upper edge surface 22 and the further lateral edge surface) provided with projecting portions 23 it will immediately be clear that the standard blocks fit into one another without difficulty. It is necessary only to put on the upper surfaces of the blocks a layer of cement corresponding to the height of the shoulders 25, and to place other standard blocks on the layer of cement in a conventional manner.

As regards the angle or end blocks, it is clear that locating cannot occur when two angle or end blocks or two parts thereof are placed one on the other, as is the case for the corner of the assembly of Figure 1. In this case, the above mentioned locating member 17, made from the same material as the insulating layer 8, is added to the groove of the angle or end block. The member 17 has shoulders 27 of the same height as the flanges 25, and it is therefore necessary only to cut the member 17 to the required size, place it in the recessed portion, put on the layer of cement and put subsequent blocks in place. The locating member will be described in detail below with reference to Figures 9 and 10.

Figure 4 shows a portion of a wall formed from an assembly of standard blocks similar to the blocks 4 and 5 of Figure 1. A concrete slab 30 bears on the load-bearing layers 7 of the upper row of blocks, the slab having been moulded in shuttering after parts 31 and 32 have been placed in the shuttering. The parts 31 and 32 each include a facing layer 33 similar to the layer 6 and an insulating layer 34 of the same thickness as the layer 8, the layer 34 being secured to a load-bearing edge 35 of the concrete slab 30.

The part 31 is shown in Figure 5 (viewed from above) and Figure 6 (side view), it being understood that the part 32 is identical thereto. The insulating layer 34, which is made from expanded organic material, has on its lower surface a recessed portion 36 in the form of a groove and on its lateral surface a succession of alternating protuberances 37 and hollows 38 which fit into the edge of the concrete slab 30 when it has been cast and which thereby holds the part 31 in place. Iron rods for the reinforcement of the slab 30 are shown at 39.

The height of the parts 31 and 32 is equal to the height of the standard blocks 4, 5 and the angle or end blocks 1 to 3 of Figure 1.

Nevertheless, the parts 31 and 32 may be cut by any conventional means existing on building sites, such as disc milling cutters, to a height h (Figure 6) corresponding to the thickness of the slab 30. Clearly, the cutting operation will be done before casting the slab.

As regards the manufacture of the parts 31 and 32, the facing layer 33 is placed in a mould with an opposing piece (not shown) having on its internal surface a succession of protuberances and hollows complementary to those which it is desired to obtain on the parts 31 and 32, and the insulating organic mass is injected between the facing layer and the opposing piece. The opposing piece has only to be made in such a manner that the surface thereof which is provided with the aforesaid succession of protuberances and hollows is smooth and possibly also lubricated, so that the opposing piece can be easily removed from the mould.

A right-angle is shown in Figure 7, made with two parts 40 and 41 each as shown for part 31 in Figures 5 and 6. In order to form the right-angle, of Figure 7, it is necessary only to remove the expanded insulating mass over a portion of the width of the two parts and to assemble the parts together. It is clear that the two parts 40 and 41 may be previously cut to enable them to fit.

Figures 8 and 9 of the drawings show alternative forms of locating members or additional joint elements which are intended to replace the projecting portions in the form of ribs of the building blocks where the latter are missing, for example in the case where two portions of angle or end blocks are placed on one another. As has already been described with reference to Figures 1, 2 and 3, the locating member 17 of Figure 8 is intended to be positioned where two recessed portions are face to face. The member 17 therefore has an upper portion 43 and a lower portion 44 of the same shape and size, corresponding to the recessed portions of the building blocks described above. Shoulders 45 of the same size as the shoulders 25 of the standard blocks 4 and 5 (Figure 1) are provided on each side of the member 17.The members 17 are located in the recessed portions of the upper surfaces of the angle or end blocks so as to be able to interlock with the blocks placed above.

The locating member 46 of Figure 9 includes a projecting portion 47 complementary in shape to the recessed portions of the blocks 1 to 5 of Figure 1. The member 46 has shoulders on each side thereof which are similar to the shoulders 45 of the locating member 17 of Figure 8. The member 46 will be located, for example, on the edges of the insulating layers 34 of the parts 31 and 32 of Figure 4, in order to be able to interlock with the blocks located above these parts.

The member 46 of Figure 9 will advantageously be stuck on the edge of the insulating layer 34, in order that the cement may be put on and the upper blocks fitted without lateral movement.

The locating members 17 and 46 of Figures 8 and 9 are advantageously made from the same material as the expanded insulating mass, i.e. an expanded organic substance such as polyurethane foam.

A slab 50 with a window stile 51 protecting a roller-blind 52 is shown in cross-section in Figure 10. On its forward face the window stile 51 holds parts 53 similar to the parts 31 and 32 respectively of Figure 4. Here, as in the embodiment of Figure 4, the slab 50 and the window stile 51 have been cast in shuttering after the parts 53 have been placed therein.

The locating member 46 of Figure 9 is stuck on the upper edge of an insulating layer 54 of the parts 53, and a layer 55 of cement of the same thickness as the shoulders 48 of the member 46 is then applied and building blocks 56 of the same form as the blocks 1 to 5 of Figure 1 are placed on the layer 55 of cement.

Figures 11 and 12 show schematically an embodiment of a mould used to manufacture the building blocks described above with reference to Figures 1 to 3. The mould (referenced 60) has a lower support 61 at the ends of which two rectangular bearing members 62 and 63 are located. The members 62 and 63 act as supports for respective jacks 64 and 65 arranged to move mould portions 66 and 67 laterally. Two uprights 70 and 71 are located on the member 62 and support an upper bar 72 on which is fixed a jack 73.

The jack 73 permits a mould portion 74, arranged to close the top of the mould 60, to be lowered. Rods 75, 76 and 77 of the jacks 64, 65 and 73 are connected to the respective mould portions 66, 67 and 74 by means of respective articulations 78, 79 and 80 in order to permit correct positioning of the various mould portions. The mould 60 is closed laterally by means of two fixed plates 81 and 82 connected to the uprights 70 and 71 by means of cross-pieces 83 and 84.

In order to produce a building block, loadbearing and facing layers 68 and 69 of said block are placed in the mould 60 against the fixed plates 81 and 82 respectively, such that the layers 68 and 69 are separated by a space.

The surfaces of the lower support 61 and the mould portions 66, 67 and 74 which contact the layers 68 and 69 are provided with respective coating 85, 86, 87 and 88 of hard rubber, and have machined portions 66a, 67a and 74a which ultimately define the projecting and/or recessed portions of the insulating layer. An inlet channel 89 for the expanded insulating material opens into the space between the layers 68 and 69 and is connected to two inlet conduits 90 and 91 for the constituents of the expanded material by way of respective opening valves 92 and 93.

The constituents for making the expanded material are well known. Let us suppose that the expanded material is a polyurethane foam. One of the constituents will be a liquid mixture containing a polyisocyanate, the other constituent a liquid mixture containing a polyol. One or each of the constituents will contain the necessary additives or derivatives, for example catalysts, accelerators, fireproofing agents, stabilisers, recticulation agents and hardeners. These additives, as well as the injection process, are well known in the art.

One of the constituents will be introduced through the conduit 90, the other through the conduit 91. Immediately after the injection, in order not to block the channel 89, the precaution is taken of providing a small additional injection of the constituent containing the polyol, so as to fill the conduit 89 with this mixture and prevent the said conduit becoming blocked after the expanded material has solidified.

Once the layers 68 and 69 have been placed in the mould, the jacks 64, 65 and 73 are operated to bring the mould portions 66, 67 and 74 against these layers and exert a pressure thereon. The constituents of the organic insulating material are injected into the space between the layers 68 and 69 through the conduits 90, 91 the valve 92, 93 and the channel 89. Expansion takes place and the insulating material fills the space between the parts 68, 69 and the mould portions 61, 66, 67 and 74. When the insulating material has solidified, the mould is opened and the finished block is removed.

The mould shown in Figures 11 and 12 forms part of an installation, not shown, including conveyors adapted to bring the facing and load-bearing layers to the mould, members for positioning the said layers, and control and adjustment devices adapted to control the smooth running of the installation.

As mentioned above, any known building material can be used for the facing and loadbearing layers. A single condition must be fulfilled in order to obtain a strong and durable bond between the expanded organic insulating mass and the surface of the building material used. This condition resides in the fact that the surfaces of the facing and loadbearing layers must be porous or rough, in order that the expanded organic insulating material may penetrate into the pores or corrugations of the parts and thus ensure this strong and durable bond.

Walls and partitions built with the building blocks described above have thermal and acoustic insulating properties. By virtue of the presence of the projecting and recessed portions, no acoustic or thermal bridge remains over the whole surface of the wall. Moreover, such walls and partitions are easy to construct, since the blocks fit well together without difficulty. The presence of the shoulders 25 on the projecting portions (Figures 1 and 2) makes it easy to apply a constant thickness of cement and thus to position the blocks correctly.

Finally, walls built with the blocks described above are very regular in their arrangement and aesthetically attractive. If plates of brick or marble, for example, are selected for the facing layer, it is possible to make very beautiful constructions having a high quality appearance.

WHAT I CLAIM IS: 1. A building block for making walls or partitions, comprising two layers of building material having opposed faces which are separated by a layer of insulating material, the periphery of the insulating layer having recessed and/or projecting portions adapted to engage corresponding portions of the insulating layer of another building block or a locating member located between said blocks, the insulating layer being formed from an acoustically and thermally insulating expanded material and being bonded to said layers of building material solely by penetration of the expanded material into pores or recesses in said opposed faces thereof, such that the three layers form a monolithic structure.

2. A building block as claimed in claim 1, wherein the peripheries of the three layers form a first pair of adjacent edge surfaces in which the periphery of the insulating layer has projecting portions, and a second pair of adjacent edge surfaces in which the periphery of the insulating layer has recessed portions.

3. A building block as claimed in claim 1, wherein one of the layers of building material is L-shaped and extends along two adjacent side faces of the other layer of building material, and the insulating layer is also Lshaped and its periphery has recessed portions on all faces of the building block where it is visible.

4. A building block as claimed in claim 1, 2 or 3, wherein each recessed portion of the insulating layer is in the form of a groove having oblique lateral walls.

5. A building block as claimed in claim 1 or 2, wherein each projecting portion of the insulating layer is in the form of a ridge having oblique lateral walls.

6. A building block as claimed in claim 5, wherein each projecting portion has respective shoulders of substantially square section at the bases of said oblique lateral walls.

7. A building block as claimed in any preceding claim, wherein one of the layers of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and/or recessed portions of the insulating layer. An inlet channel 89 for the expanded insulating material opens into the space between the layers 68 and 69 and is connected to two inlet conduits 90 and 91 for the constituents of the expanded material by way of respective opening valves 92 and 93. The constituents for making the expanded material are well known. Let us suppose that the expanded material is a polyurethane foam. One of the constituents will be a liquid mixture containing a polyisocyanate, the other constituent a liquid mixture containing a polyol. One or each of the constituents will contain the necessary additives or derivatives, for example catalysts, accelerators, fireproofing agents, stabilisers, recticulation agents and hardeners. These additives, as well as the injection process, are well known in the art. One of the constituents will be introduced through the conduit 90, the other through the conduit 91. Immediately after the injection, in order not to block the channel 89, the precaution is taken of providing a small additional injection of the constituent containing the polyol, so as to fill the conduit 89 with this mixture and prevent the said conduit becoming blocked after the expanded material has solidified. Once the layers 68 and 69 have been placed in the mould, the jacks 64, 65 and 73 are operated to bring the mould portions 66, 67 and 74 against these layers and exert a pressure thereon. The constituents of the organic insulating material are injected into the space between the layers 68 and 69 through the conduits 90, 91 the valve 92, 93 and the channel 89. Expansion takes place and the insulating material fills the space between the parts 68, 69 and the mould portions 61, 66, 67 and 74. When the insulating material has solidified, the mould is opened and the finished block is removed. The mould shown in Figures 11 and 12 forms part of an installation, not shown, including conveyors adapted to bring the facing and load-bearing layers to the mould, members for positioning the said layers, and control and adjustment devices adapted to control the smooth running of the installation. As mentioned above, any known building material can be used for the facing and loadbearing layers. A single condition must be fulfilled in order to obtain a strong and durable bond between the expanded organic insulating mass and the surface of the building material used. This condition resides in the fact that the surfaces of the facing and loadbearing layers must be porous or rough, in order that the expanded organic insulating material may penetrate into the pores or corrugations of the parts and thus ensure this strong and durable bond. Walls and partitions built with the building blocks described above have thermal and acoustic insulating properties. By virtue of the presence of the projecting and recessed portions, no acoustic or thermal bridge remains over the whole surface of the wall. Moreover, such walls and partitions are easy to construct, since the blocks fit well together without difficulty. The presence of the shoulders 25 on the projecting portions (Figures 1 and 2) makes it easy to apply a constant thickness of cement and thus to position the blocks correctly. Finally, walls built with the blocks described above are very regular in their arrangement and aesthetically attractive. If plates of brick or marble, for example, are selected for the facing layer, it is possible to make very beautiful constructions having a high quality appearance. WHAT I CLAIM IS:

1. A building block for making walls or partitions, comprising two layers of building material having opposed faces which are separated by a layer of insulating material, the periphery of the insulating layer having recessed and/or projecting portions adapted to engage corresponding portions of the insulating layer of another building block or a locating member located between said blocks, the insulating layer being formed from an acoustically and thermally insulating expanded material and being bonded to said layers of building material solely by penetration of the expanded material into pores or recesses in said opposed faces thereof, such that the three layers form a monolithic structure.

building material constitutes a facing element and the other layer of building material constitutes a load-bearing element which is thicker than the facing element.

8. A building block as claimed in any preceding claim, wherein one of the layers of building material is formed by a concrete slab, and the face thereof to which the insulating layer is bonded has a succession of protuberances and hollows thereon which overlap corresponding protuberances and hollows on the adjacent face of the insulating layer.

9. A building block as claimed in any preceding claim, wherein the expanded material is a closed cell organic foam.

10. A building block as claimed in claim 9, wherein the organic foam is a polyurethane foam.

11. A building block substantially as hereinbefore described with reference to Figures 1 to 3, or Figures 4 to 7, or Figure 10 of the accompanying drawings.

12. A building structure incorporating one or more building blocks as claimed in any preceding claim.

13. A method of manufacturing a building block as claimed in any one of claims 1 to 11, comprising placing two layers of building material in a mould such that opposed faces thereof are separated by a space, the mould defining recessed and/or projecting portions on the periphery of said space; closing the mould; and injecting an acoustically and thermally insulating expanded material into the space between said layers of building material such that the expanded material penetrates into pores or recesses in said opposed faces and thereby bonds the layers into a monolithic structure.

14. A method of manufacturing a building block as claimed in any one of claims 1 to 11, substantially as hereinbefore described.

15. A mould for performing the method claimed in claim 13 or 14, comprising a plurality of mould portions, at least some of which are movable, which are arranged to enclose the periphery of the two layers of building material separated by a space and which define the recessed and/or projecting portions on the periphery of said space, and means for injecting the expanded material into said space between the two layers of building material.

16. A mould as claimed in claim 1S, wherein surfaces of the mould portions which are in contact with the two layers of building material are coated with a resilient material.

17. A mould as claimed in claim 16, wherein the resilient material is hardened rubber.

18. A mould as claimed in claim 13, 16 or 17, wherein the movable mould portions are controlled by jacks in such a way as to exert a pressure on the two layers of building material.

19. A mould for performing the method claimed in claim 13 or 14, substantially as hereinbefore described with reference to Figures 11 and 12 of the accompanying drawings.