GB2472068A

GB2472068A - Wall structure formed from insulating parallelepiped blocks

Info

Publication number: GB2472068A
Application number: GB0912830A
Authority: GB
Inventors: Peter Waldron
Original assignee: Construction Innovation Ltd
Current assignee: Construction Innovation Ltd
Priority date: 2009-07-23
Filing date: 2009-07-23
Publication date: 2011-01-26
Also published as: GB0912830D0; EP2456932A2; WO2011010127A3; WO2011010127A2

Abstract

The block 10 comprises two sides 16 which are joined together by at least one web 21, column forming voids 12, are defined within the blocks between a pair of webs or a web and an end of the block. The block comprises a top 15 and bottom 17 surfaces, one of which defines at least one cylindrical flange 26 and the other defining at least one corresponding cylindrical groove 28 such that two blocks can be engaged in a mating configuration when one is placed upon the other. When two blocks are engaged in a mating configuration the blocks are locked from movement with respect to a plane defined by the mating top and bottom surfaces of two blocks. When concrete is poured into the void the pressure of the concrete presses the flange and groove together so that the friction between the pair is increased. The blocks may be formed from expanded polystyrene.

Description

Concrete Wall Structure This invention relates to building structures and to methods of making building structures. The invention is particularly concerned with the technique of using hollow blocks of expanded polystyrene or like insulating material that can be moulded to shape and which can be stacked together to provide an internal network of channels into which concrete can be poured to form a structural component such as a wall. The channels form columns and interconnecting webs that, in the absence of the formwork constituted by the blocks, can give the wall a waffle-or lattice-like appearance. In any event, the concrete forms the structural part of the wall, while the formwork constitutes two layers of insulation, giving the final wall good thermal characteristics. They stay in position, forming part of the structure of the building and, on what is the inside of the building, the insulation receives an internal wall board or like finishing, eg by adhesion thereof to the insulation, and, on the outside, receives a finishing layer, suitable for protection against the weather and to give appropriate appearance (eg of stone).

BACKGROUND

Numerous criteria and issues come into play with such a wall construction and the present invention is concerned with a particular issue of corner formation.

Numerous documents disclose special corner arrangements. An obvious route is the use of special corner blocks. The only problem is that it is limiting on the one hand and expensive on the other. Thus, it is limiting because each corner can only form a particular angle between adjacent walls, typically perpendicular; it is expensive because for each angle required a special corner piece is needed and the more angles that are catered for, the more expensive the system becomes.

US-B-6922962 discloses one arrangement of special corners, as well as corresponding flat pieces. US-B-6691481, WO-A-2007/082378 and US-B-688O3O4disclose similar arrangements, the latter providing several different angles.

US-A-5465542 discloses such flat blocks, but no corner pieces. Instead, the installer is expected to mitre side pieces at corners. This enables any angle to be produced and is, of course, inexpensive in terms of provision of blocks. Unfortunately, the down side is the difficulty of mitring blocks with sufficient accuracy that holes are not created enabling concrete entering the corners to leak out. Indeed, since the corners are mitred, there is no interlocking between them, so that the pressure of the wet concrete surely presses them apart requiring special fixing means to keep the corners together.

Indeed, this is the approach taken with many systems and there also numerous documents dealing with this specific problem, for example US-A-5782050 where various braces are provided.

FR-A-2349707 discloses a hollow block that has scallops formed at its ends, sometimes to receive blanks so that ends can be closed when the blocks are to form an outside part of the formed wall, or left open when the ends span the wall to be cast. This arrangement provides the advantage that only one form is required to form both flat walls and right angle corners. Nevertheless, the form is limited to these two angles, either 90° or 180°.

The same is true of the modular elements disclosed in EP-A-163117 that require dovetail elements to join blocks side-by-side. However, there are circular ribs and grooves between adjacent blocks and around vertically extending forms for subsequent reception of concrete. Moreover, this document recognises the problem of concrete leaking between vertically stacked blocks. This problem can cause lifting of blocks, increasing the size of the leak, which can then become catastrophic. EP-A-163117 suggests an annular flap in the bottom of a form that, under pressure from the poured concrete seals against the inside of the form and closing the joint between adjacent blocks. However, the resilience necessary for such a flap would not appear to be achievable with relatively rigid polystyrene foam; which in turn suggests that the block is made of a solid plastics material. That would seem to render the block impractical.

Although not a concrete formwork, US-A-6161357 discloses a brick construction having both horizontal and vertical passageways formed therethrough, in which the horizontal passageways are sealed between adjoining bricks by vertically oriented ribs and slots, and in which the vertical passageways are sealed between adjoining bricks by circular ribs and slots. The latter feature enables adjoining bricks to be disposed at different angles with respect to one another so that corners can be formed at any angle while still maintaining the integrity of the passageways. These enable services to be run, but can also be reinforced with concrete. DE-U-19903287 discloses a similar block.

It is an object of the present invention to provide a block that enables multiple angles to be formed.

BRIEF SUMMARY OF THE DISCLOSURE

In accordance with the present invention there is provided a parallelepiped block of insulating material comprising: two sides and two ends, and open top and bottom surfaces wherein the sides are joined by one or more webs so that, between the sides, and between two facing webs, or between a web and an end, column-forming voids are defined; and wherein an upstanding circular flange is disposed on one of the top and bottom surface around each said void where the void opens in said surface; and a corresponding circular groove is disposed on the other of said top and bottom surface also around each said void where the void opens in said surface; whereby one block is disposable on top of another block in a plane of mating top and bottom surfaces in one of two positions: a first of which positions is where the sides of said top and bottom blocks are parallel with one another and one or more said flanges of one block are in engagement with corresponding grooves in the other block; and a second of which positions is where said blocks are at an angle with respect to one another in said plane, with an end one of said flanges or grooves on one block in engagement with a corresponding one of said grooves and flanges on the other block, wherein, in either position, said engagement locks one block with respect to the other against movement in said plane and seals said void between adjoining blocks against leakage of concrete, the hydrostatic pressure of concrete poured into said voids serving to press said flange and groove into engagement with one another whereby friction between them is enhanced to resist the lifting force of caused by concrete seeping between horizontal faces of stacked blocks.

Thus, a column can be formed by pouring concrete into the voids formed by stacked blocks, which may be at any angle with respect to one another. Indeed, T-shaped plans may be provided, or gently curving walls. Furthermore, the material of the wall and the dimensions of the groove and flange are selected to achieve the deflection needed to enhance frictional grip between a block and the one stacked above it.

Indeed, preferably, said groove is formed near an edge of said void to define a lip that is deflected by said hydrostatic pressure to press the side of the groove adjacent said lip against said flange.

Preferably, said voids are circular cylindrical.

Preferably, each void is disposed in a square surface of the top surface, which square surface has first and second opposing edges, comprising the intersection of said sides with said top surface, a third edge comprising an imaginary line perpendicular to said first and second edges and bisecting a line joining the centres of adjacent square surfaces, and a fourth edge comprising the intersection of one end with said top surface or another of said imaginary lines. Said void may be central in said square surface.

Pips are preferably also disposed on said top surface, outside said rims, in symmetrical disposition and rotational orientation about perpendicular axes centred on the centre of said square surface, and corresponding indents may be disposed in the bottom surface.

Each said rim may trapezoidal in section.

Scallops are preferably formed in said top and bottom surfaces in said webs whereby beam-forming voids are defined between blocks when they are disposed in said first position, which beam-forming voids connect adjacent column-forming voids, the rim and the groove, around said column-forming void being absent where said scallop intersects the column-forming void. Said rim may connect with a channel rim formed in said top surface beside said beam-forming void, and a corresponding channel groove is formed in said bottom surface.

Preferably, there are at least two concentric rims, and corresponding grooves, around each void. Said concentric rims, and corresponding grooves, may connect with a corresponding number of channel rims and grooves, where these are provided.

Preferably, said block is formed from a material easily cut. Preferably, said material is expanded polystyrene, which can be cut with a hot wire.

Preferably, said blocks are cuboid.

The invention also provides a wall comprising blocks as defined above stacked upon one another and interleaved so that a block is seated on two blocks underneath.

Preferably, said adjoining end walls are scalloped where they coincide with a scallop in a web.

Preferably, a wall as defined above comprises a corner between an end block and a mating block where the corner turns through an angle ci centred on the void through the end block, and wherein corner edges of the end block are cut off at the same angle a so that the cut-off corner is, on one side of the end block, flush with the side of the mating block and, on the other side of the end block, contiguous with the end of the mating block.

Preferably, the cut-off corner edges are adhered to the end block, one on the uncut end of the end block, and the other on the in-side of the end block adjacent the cut, thereby to create a new flush end of the end block, which end is turned at the angle a to the end block and is contiguous with the end of the mating block.

Thus, by virtue of the invention, a corner in a wall can be constructed turning through any angle within reason. With angles of turn greater than a right angle, there are potential problems with sealing if the void has to be penetrated and, therefore, sealed against an abutting block. However, beyond these complications, the building of walls and corners between them is not much more complicated than toy building blocks.

If the walls are of expanded polystyrene or other suitable thermoplastics material, the blocks can be cut and shaped as required using a hot wire.

The primary ability of the present invention is to enable a corner to be constructed at a variety of angles while maintaining the integrity of a column at the corner, and enabling not only the column-forming void to be sealed, but also to precisely locate the blocks with respect to one another. The blocks may have other surface characters that interlink between mating surfaces when blocks are aligned on top of one another.

However, these are easily removed when angles (other than right angles) are desired between them.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a block according to the present invention; Figure 2 is a plan view of blocks shown in Figure 1 in a wall forming a T-section; Figure 3a is a plan view of a wall using blocks according to Figure 1, disposed in a corner having a shallow angle, and Figure 3b is a section on the line B-B in Figure 3a; Figures 4a to c show arrangement of blocks at different layers in a wall through a corner at a sharper angle, and the modifications made to the standard block for the corner; Figure 5 shows the possibility of forming a bay-wall using blocks according to the present invention; and Figure 6 shows the possibility of making an acute angle corner between blocks according to the present invention.

DETAILED DESCRIPTION

In Figure 1, a block 10 is moulded from expanded polystyrene or like material. It is moulded with a plurality of cylindrical column-forming voids 12 between side walls 16 and between an end wall 20 and a web 21 (in the case of end voids 12a), or between two facing webs 21 (in the case of intermediate voids 12b). Preferably there are five voids 12 per block 10, although other configurations are possible. Preferably, each void 12 defines in plan a square 14 of the top surface 15 of the block 10. The square 14 has opposing sides 16a formed by the side walls 16 of the block 10. For a void 12a adjacent an end wall 20 of a block 10, the end wall 20 forms an orthogonal third side of the square 14. Finally, the fourth side of the square 14 is formed by an imaginary line 18 that bisects the web 21 between two intermediate voids 12b, or between an intermediate void 12b and an end void 12a. Each square 14 is centred on a corresponding void which, being circular means that the minimum thickness d of the wall between a side 16 or end 20 and a void 12 is equal to half the width D of the block 10 less the radius R of the void 12. Furthermore, the length L of the block 10 is equal to n*D, where n is the number of voids 12 in each block. The height H of each block is selected as appropriate. Thus, a typical set of dimensions for a block 10 is (D x L x H) of 225 x 1125 x 300 millimetres.

The minimum dimension d represents the thickness of insulation in the final wall, although this will appear both on the inside and outside of the wall and is selected accordingly. The Radius R of the voids 12 is selected to ensure adequate strength, once concrete is cast, to satisfy the structural requirements of the building when completed. d is preferably about 37.5 mm and R is about 75 mm, in a typical application.

In each corner of the square 14, on top surface 15 of the block 10, is defined a pip or stud 22. A corresponding indent 24 is formed in the opposing base 17 of the block 10.

Accordingly, when two blocks 10 are placed one on top of the other, the pips 22 on the lower block engage the indents 24 in the upper block. This serves to locate the blocks securely with respect to one another in the plane of connection between them. This, in most practical applications, will be a horizontal plane containing the top and bottom surfaces 15,17.

Furthermore, each void 12 is provided, on the top surface 15, with at least one circular rim or upstanding flange 26, or preferably a pair of them, spaced from internal wall 12c of the void. Likewise, each base 17 is provided with a channel or groove 28 around each void 12 where it opens at the base 17. The rim 26 likewise engages the channel 28 when two blocks are placed one on top of the other.

Turning to Figure 2a and b, the pips 22 are arranged in a square formation having perpendicular axes 125, 127 centred at c, being the centre of the square surface 14, and defining four quadrants Ito IV. The axis 127 is the longitudinal axis of the block 10 that runs parallel to its sides 16. The axis 125 is perpendicular thereto. This arrangement enables the blocks 10 not only to be placed immediately above one another, so that their respective sides 16 are parallel, but they can also be located at right angles to one another. A corner of a building can therefore easily be formed. Also they can be stepped with respect to one another, so that courses can be built like normal brick walls. For both these purposes the pips 22 are circular, but they can be any shape, and need not be positioned exactly in the square formation shown in the drawings, provided they are a) disposed symmetrically with respect to (any) perpendicular axes centred on centre c, and, b) their shape is a right-angled rotational translation about said centre c of the corresponding pip in an adjacent quadrant defined by the relevant axes. The drawings illustrate the simplest possible arrangement of pips, but many other arrangements are of course possible.

Furthermore, a T-section wall can be formed, as shown in Figure 2b. It is to be noted that the column forming voids 12 of blocks placed above one another, whether aligned with their sides 16 parallel, or at right angles to one another, are contiguous so that, when the final wall is built, and concrete is cast, the voids 12 form concrete columns that can support a buildings. Indeed, prior to casting, it would be common to insert steel reinforcements into the voids 12. However, such is well known in the art.

Returning to Figure 1, adjacent voids 12 are connected, at the top and bottom surfaces 15,17 of each block 10, by web-forming channels 32 formed across the webs 21 of the block 10. When one block is placed on another, mating web-forming channels 32 combine to form (preferably near-circular section) cross-connections between the voids 12. Apart from anything, this facilitates casting, since pouring concrete into one void, provided it is readily flowable, is sufficient to fill all the voids, since there will be transport between voids across the channels 32. However, once cured, the webs formed by the channels 32 strengthen the construction and provide rigidity in the shear direction in the plane containing the columns. Again, steel reinforcements may be located in the channels 32 as the blocks are being laid.

When two blocks are adjacent end 20 to end 20, or end 20 to side 16, a web-forming channel 32a is easily cut using a hot wire -provided the material of the blocks is expanded polystyrene or other thermoplastic. Alternatively, a knife or saw could be used, especially if the material is not thermoplastic. Otherwise, the ends 20 of the blocks 10 are closed, so that they form a seal and prevent concrete leakage. In this respect, the rim 26 and channel 28 form a significant barrier to concrete leakage. This enables the concrete to be rendered wetter, so that its pouring is facilitated. This is an important function of the rim 26 and channel 28, and is described further below.

However, the construction of the rims and channels also enables walls to be created at angles other than 90 or 180. The rim 26 is circular and is centred at c, in the centre of the voids 12. Consequently, referring to Figure 3a, if a fillet 52 is removed from the end of a first block lOa, a second block lOb can be disposed at an angle a to the block lOa, the fillet 52 being triangular in section, also having an angle a. The cut off fillet 52 can, if desired, be inserted in the gap 54 on the outside of the angle being turned. Likewise, to complete the shape of the building, a further fillet 56 can be removed from the block 1 Oa and inserted in the space 58 on the inside of the block 1 Oa.

When two blocks 10 are placed end to end, adjacent end voids 12a are separated by a distance S1 which is equal to 2(R+d). In rotating block lOb through the angle a, and removing the fillet 52, this does not alter the distance S2, being the separation between the voids l2aa,l2ab. Accordingly, on top of the butted blocks lOa,b a new block lOc (shown in dotted lines in Figure 3a) can be positioned, with its voids 12a,b mating securely with the voids l2aa,l2ab on the blocks lOa,lOb below. However, the pips 22 on the block lOa around the void l2aa must be removed, as these are now rotationally displaced with respect to the indents 24 on the block lOc.

Prior to addition of the new block lOc, a web-forming channel 32b is formed between the butting blocks. The only difference between the channels 32b and the channels 32a in Figure 2a is the direction that they take. It is to be noted that the thickness d1 of the insulation is at no time less than d, even though fillets 56 might be entirely removed.

While a single rim, or flange 26 on the top surface 15 of the blocks 10 is shown for the sake of clarity in the drawings, (and a single corresponding channel or groove 28 in the base 17), it may be preferred that they are paired, concentric rims 26a,b, as shown in the inset A in Figure 3a, and also magnified in section (along the line B-B in Figure 3a) in Figure 3b. (Indeed, in the inset, the rims are also shown extending around the corner to border the channel 21 forming a channel barrier 26f.) In Figure 3b, two blocks lOa,c are shown one lOc on top of the other lOa, with mating top 15 and bottom 17 surfaces. The rims 26a,b extend into the corresponding grooves 28a,b, with rim/groove pair 26a,28a being closer to the void 12. When concrete is poured, a hydrostatic pressure P applies which is transferred into the gap 157 between the surfaces 15,17. This results in a spreading force between those surfaces, which, since the block lOa cannot go downwards (presumably it is seated on the ground or on a block beneath) the block 10 is merely lifted with a force proportional to pressure P. This tends to separate the blocks, allowing more concrete to seep into the gap 157.

However, because it is relatively thin and flexible, the pressure P deflects outwardly the lip G between the void 12 and the groove 28a. This tends to close the gap between the lip G and rim 26a, potentially displacing that rightwardly against ridge 28c, which finally might itself be pressed rightwardly against end wall 28d. However, end wall 28d is rigidly supported by the bulk of the block lOc, and therefore does not move, relatively.

Likewise, shoulder H of block lOa is supported by the bulk of that block, so it is not affected by the hydrostatic pressure P compared with lip G above.

Consequently the effect of the outward displacement of the lip G and ridge 28c, and rims 26a,b, is to squeeze them all together so that the frictional grip between them prevents the hydrostatic pressure P from lifting the block 1 Oc off the block 1 Oa below. It is necessary for this effect to be achieved that there is some resilient deflection, at least of the lip G, and probably also of the ridge 26a. However, in order to provide grip and resistance to lift, the lip G and the ridge 26 must not be so thin and flexible that they provide no structural resistance to lift -they must be strong enough to resist the lift that occurs. Indeed, part of the purpose of having the extra ridge 26b (with the resultant intermediate ridge 28c) is that the vertical area over which the sideways force applied by the pressure P is enlarged so that the frictional effect is further enhanced. Also, the material of the block needs to be such that there is significant static friction between faces pressed together but placed in shear; such as between expanded polystyrene foam surfaces.

If the rims (either a single one 26, or double one 26a,b) extend alongside the channels 21 (as shown at 26f in the modified inset A in Figure 3a) then it is necessary that they be removed in the section marked X-Y in Figure 3a when the blocks are being overlapped other than directly one above the other. This is one reason why such channel barriers 26f (either single ones or double) might be omitted. Indeed, it is to be noted that the distance (2d) to be traversed by liquid attempting to escape is much further here than at the edge where it is just d. However, this is not necessarily the point as, once sufficient area is exposed under a block to lift that block, the area will increase as the block lifts until ultimately the concrete is able to escape entirely and disrupt the wall. Consequently, the absence of a double rim 26a,b, or of channel barriers 26f, is somewhat determinative of how liquid the concrete can be arranged to be, since that determines how penetrating it will be.

Incidentally, the rims 26a,b and corresponding grooves 28a,b are shown somewhat trapezoidal in section in Figure 3b. This facilitates assembly of the blocks and, in one respect, enhances the seal, because the taper of the rim can be a tight fit in the taper of the groove. However, this is not necessarily advantageous, because the weight of the blocks may not be substantial enough to press the tapers significantly into engagement.

On the other hand, the normal to the side surfaces of the rims and grooves do have a vertical component, so that there will always be an element of lift by the hydrostatic pressure with trapezoidal rims, which is removed, or at least mitigated, if the sides of the rims are cylindrical.

Turning to Figures 4a to c a wall 100 is shown that turns through a larger angle 13. In Figure 4a block lOe is modified and is butted against block lOf. End void 12e of the block 1 Oe forms a column at corner 102 of the wall 100. The next layer up has ordinary block lOg butted at 106 against modified block lOh. However, now void 12f of the block lOh is at the corner 102 of the wall 100. The modification of the blocks lOe,lOh is shown in Figure 4c where fillets 52a and 56a are shown removed from the block lOh and re-applied at 58a and 54a respectively. The same modification is made to the block lOe.

Turning to Figure 5, here, blocks lOm are formed by cutting ordinary blocks 10 into pairs of voids, and then modifying their ends slightly so that they are trapezium-shaped in plan (or possibly wedge-shaped if only one end is trimmed -this is preferred, as trimming a relatively large angle off one end of a block is easier than half that amount from each of two ends). This enables a bay-wall 100' to be formed, and so that a smooth curving wall 100' can be provided.

Finally, with reference to Figure 6, a wall 100" is shown which turns through an angle in excess of 90, for example about 125. Exactly the same arrangements persist here as with the embodiments described above, with various fillets F from the different blocks lOm,n having to be removed and re-applied elsewhere in order to achieve a smooth corner 102'. Appropriate removal of the pips 22 is, of course, necessary and, with such a sharp angle, it is also necessary to remove some of the rim 26, as shown at 26a.

Indeed, it would be necessary with the block lOp (not different, in appearance from above, from the block lOm underneath, and which is complete and extends under the block iOn) to have the void 12v open; it being closed by sealing against side 16f. This would provide substantial side load on the sealing block iOn, and also opening load on the open "jaws" 1OP1,1OP2. Nevertheless, sufficient rims would remain in association with the void 12v in the rows above and below to keep the jaws 1OP1,1OP2 closed.

Furthermore, in connection with the end void 12w, there would be adequate shear connection between interlocking blocks, to provide the necessary integrity during casting and to avoid displacement of the block iOn and disruption of the corner 102'.

Accordingly, the present invention provides a means whereby any corner can be formed in a wall using only a single form. The modifications required to make different angles of wall are not challenging and can be effected on site without a great deal of expertise being required. Importantly, by blocks being able to alternate the direction they take, they tie each other in so that there is no special connections that need to be made between the walls to keep them in position. The circular rims and corresponding grooves between blocks stacked on one another are instrumental in this respect and in maintaining the integrity of the blocks in any direction in the plane of the mating top and bottom surfaces.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A parallelepiped block of insulating material comprising: two sides and two ends, and open top and bottom surfaces wherein the sides are joined by one or more webs so that, between the sides, and between two facing webs, or between a web and an end, column-forming voids are defined; and wherein an upstanding circular flange is disposed on one of the top and bottom surface around each said void where the void opens in said surface; and a corresponding circular groove is disposed on the other of said top and bottom surface also around each said void where the void opens in said surface; whereby one block is disposable on top of another block in a plane of mating top and bottom surfaces in one of two positions: a first of which positions is where the sides of said top and bottom blocks are parallel with one another and one or more said flanges of one block are in engagement with corresponding grooves in the other block; and a second of which positions is where said blocks are at an angle with respect to one another in said plane, with an end one of said flanges or grooves on one block in engagement with a corresponding one of said grooves and flanges on the other block, wherein, in either position, said engagement locks one block with respect to the other against movement in said plane and seals said void between adjoining blocks against leakage of concrete, the hydrostatic pressure of concrete poured into said voids serving to press said flange and groove into engagement with one another whereby friction between them is enhanced to resist the lifting force caused by concrete seeping between the faces of blocks stacked vertically.
2. A block as claimed in claim 1, in which said groove is formed near an edge of said void to define a lip that is deflected by said hydrostatic pressure to press the side of the groove adjacent said lip against said flange.
3. A block as claimed in claim 1 or 2, in which said voids are circular cylindrical.
4. A block as claimed in claim 1, 2 or 3, in which each void is disposed in a square surface of the top surface, which square surface has first and second opposing edges, comprising the intersection of said sides with said top surface, a third edge comprising an imaginary line perpendicular to said first and second edges and bisecting a line joining the centres of adjacent square surfaces, and a fourth edge comprising the intersection of one end with said top surface or another of said imaginary lines.
5. A block as claimed in claim 4, in which said void is central in said square surface.
6. A block as claimed in claim 4 or 5, in which pips are disposed on said top surface outside said rims in symmetrical disposition and rotational orientation about perpendicular axes centred on the centre of said square surface, and corresponding indents are disposed in the bottom surface.
7. A block as claimed in any preceding claim, in which each said rim is trapezoidal in section.
8. A block as claimed in any preceding claim, in which scallops are formed in said top and bottom surfaces in said webs whereby beam-forming voids are defined between blocks when they are disposed in said first position, which beam-forming voids connect adjacent column-forming voids, the rim and the groove, around said column-forming void being absent where said scallop intersects the column-forming void.
9. A block as claimed in claim 8, in which said rim connects with a channel rim formed in said top surface beside said beam-forming void, and a corresponding channel groove is formed in said bottom surface.
10. A block as claimed in any preceding claim, in which there are at least two concentric rims, and corresponding grooves, around each void.
11. A block as claimed in claims 8 and 9, in which said concentric rims, and corresponding grooves, connect with a corresponding number of channel rims and grooves.
12. A block as claimed in any preceding claim, in which said block is formed from a material easily cut.
13. A block as claimed in claim 12, in which said material is expanded polystyrene, which can be cut with a hot wire.
14. A block as claimed in any preceding claim, in which said blocks are cuboid.
15. A wall comprising blocks as claimed in any preceding claim, wherein said blocks are stacked upon one another and interleaved so that a block is seated on two blocks underneath, and in which concrete is cast into said voids to provide structural rigidity to the wall.
16. A wall as claimed in claim 15, in which the ends of adjoining blocks are scalloped where they coincide with a scallop in the web of a block above or below.
17. A wall as claimed in claim 15 or 16, comprising a corner between an end block and a mating block, each being a block as claimed in any of claims 1 to 14, in which the corner turns through a non-perpendicular angle a, centred on the void through the end block, and wherein corner edges of the end block are cut off at the same angle a so that the cut-off corner is, on one side of the end block, flush with the side of the mating block and, on the other side of the end block, contiguous with the end of the mating block.
18. A wall as claimed in claim 17, in which the cut-off corner edges are adhered to the end block, one on the uncut end of the end block, and the other on the in-side of the end block adjacent the cut, thereby to create a new flush end of the end block, which end is turned at the angle a to the end block and is contiguous with the end of the mating block.
19. A block, and a wall constructed from such blocks, substantially as hereinbefore described with reference to the drawings.