GB2394730A

GB2394730A - Mortarless brick and locking bolt building system

Info

Publication number: GB2394730A
Application number: GB0324037A
Authority: GB
Inventors: John Hugh Orchard Morrison
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-10-19
Filing date: 2003-10-14
Publication date: 2004-05-05
Anticipated expiration: 2023-10-14
Also published as: GB2394730B; GB0324037D0; GB0224342D0

Abstract

A mortarless building system combines interlocking bricks 1 secured with segmentally connectable bolts 2. Each brick is recessed on its underside and has apertured studs 20 protruding from its upper surface for locating within the recess of the brick above. Locking bolts 2 with integral upper threaded sockets 7 are passed through any number of the apertured studs so as to secure successive courses.

Description

BUILDING SYSTEM

This invention relates to a building system, more particularly to a system and a corresponding method for creating various forms of structures, in particular walls. The invention also relates, in more specific aspects, to specially designed bricks and locking bolts for use in the building system, which may be put to a variety of uses for creating structures that may be more easily and quickly assembled and dismantled as compared with many conventional building systems. Traditionally masonry structures have used the technique of bonding together solid bricks with a mortar binding agent applied in a wet form, which is robust but time consuming and expensive to construct, and demolish when required.

Hitherto there have been several published proposals for brick construction systems which do not rely on mortar and which thus attempt to ameliorate these drawbacks, such as: GB-A-706:227, GB-A-426535, GB-A1421240, EP-A-

0791697, FR-A-2808036, DE-A-19812419andWO-A-0019026. These prior proposals generally use a combination of bricks which are laid in an overlapping manner, with rods or pegs threaded through the bricks, or placed in-

situ, with the bricks placed over the rods.

None of these prior art building systems however lives up to its aims of

providing a building system applicable to a wide range of structures that is optimally quick and efficient to construct, modify and demolish as and when required, as compared with conventional mortar-based building systems.

Accordingly, the present invention provides a new building system, in addition to its novel component elements, and a corresponding method of building various structures with it, which enables a wide variety of structures to be constructed and dismantled when necessary with improved efficiency, speed, effort and cost.

Accordingly, in a first aspect the invention provides a system for building a structure, comprising: a plurality of bricks, each brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure; and a plurality of locking bolts, each comprising a threaded shaft and a head section hcluding a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure.

In a second aspect the invention provides a method of building a structure, comprising: providing a plurality of bricks, each brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure; providing a plurality of locking bolts, each comprising a threaded shaft and a head section including a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure; and placing said bricks adjacent one another in sequential courses of said structure, each said course being secured to the course above and/or below by means of said locking bolts being inserted through selected ones of said

apertured studs in the bricks and clamped into the head section of a corresponding locking bolt in the adjacent course.

In practical embodiments of this method aspect of the invention, especially in the case of the building of a wall or other fixed structure, the first course of bricks may if necessary, or preferably, be formed as a foundation course within which are located threaded head sockets of the locking bolts to provide anchoring means for the first course of locking bolts used to build the structure from thereupwards.

In the building method of the invention, the locking bolts may be inserted in any desired or selected number or configuration of the apertured studs provided in the relevant bricks. Thus, either all the studs in the bricks may be used for locking and building up the structure, or alternatively only some of them may be so used, as the type or demands of the structure dictate.

In further aspects of the invention there are provided the brick and the locking bolt independently, for use in the above defined system and method.

Thus, according to a third aspect the present invention provides a brick for use in building a structure, the brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure.

Preferably the studs on the top of the brick are configured in a symmetrical array, ea. in a generally square or rectangular configuration, such as preferably to substantially match the size and shape of at least a portion of the recess(es) in

the underside of at least one other like brick, such that the bricks in adjacent courses of the structure can be located and anchored one above another, ea. in a lapped arrangement, by virtue of studs in the top of one brick locating within the recess(es) in the underside of at least one other like brick.

ha preferred embodiments of the brick the recessed underside is formed with simply a single generally square or rectangular recess or hollowed out section, the internal dimensions of which are designed to substantially match or be slightly greater than the corresponding external dimensions of the array of studs on the top of a like brick which are to be located therein in the building of the structure. Alternatively, discrete recesses or holes may be provided to accommodate individual respective studs.

In an even further alternative form of brick, it may be formed with thin external walls but wherein the recessed or hollowed out underside is formed with a plurality of inwardly extending rib, fin and/or buttress supporting elements which define the said internal dimensions which substantially match or are slightly greater than the corresponding external dimensions of the studs on the top of a like brick which are to be located therein in the building of the structure. Furthermore, according to a fourth aspect the present invention provides a locking bolt for use in building a structure comprising a plurality of courses of bricks, the bolt comprising a threaded shaft and a head section including a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure.

Preferably the head section of the bolt has a width or diameter which is greater than that of the shaft and, even more preferably, substantially matches the width

or diameter of the apertured studs on the bricks. The head section of the bolt is furthermore preferably externally shaped for rotational clamping with a tool, ea.

a spanner or like implement.

The brick construction according to the invention is unique in its flexibility, strength and speed of construction. It is simple and has fundamental differences from the aforementioned prior art inventions. The principle of the present

invention is that the bricks are configured for accurate location, in a lapped arrangement, and rely on prestress from the connecting bolts for their strength.

The configuration of the brick's top and bottom surfaces allows for flexibility in the arrangement of the bricks, such that walls may be constructed with piers, returned to form corners, or all manner of alternative permutations. The abutting faces of the bricks are preferably flat, with no interlocking projections or recesses. Owing to the accuracy of location, achieved by the interlocking of successive layers or courses of bricks, tight joints between bricks are achievable.

In the system of the invention the bricks are connected with threaded bolts or rods. The bolts or rods are preferably shorter in length than the full height of the wall or other structure to be built, preferably fabricated to a length which is a multiple of the brick depth, plus whatever dimension is practically required for fixing. The overall depth of the bolt head is preferably such as to allow for succeeding bricks to be placed thereover without touching the top of the bolt head. The bolts are sequentially connected as the wall or other structure rises in height, each threaded through the hollow studs and screwed into the bolt heads below.

Once fully tightened the bolts hold the wall assembly together in a compressed state. This precompression, together with the easy to assemble and locate bricks, combines to form a strong construction with tolerances which are tight, r elated more to manufacturing than hitherto achieved construction tolerances.

The system of the present invention ameliorates or solves many of the problems associated with traditional masonry construction techniques, and in addition it has significant advantages and a range of applications. For example, structures according to the invention are fast to construct, the bricks may be laid at speed and once tied together with the connecting bolts no time is needed to wait fo' mortar to set.

The recessed (or hollow), preferably thin section bricks used in the invention can be made so as to be relatively light and easy to handle. The preferred recess or hollow section of the bricks is also potentially beneficial, acting to a degree as a heat insulator.

Having no mortar, structures constructed from the bricks according to the invention can be dismantled with ease.

The preferred short length of the bolts allows flexibility, as small and large service holes can be formed with relative ease. If a hole needs to be cut into a wall after it is built, prestress around the hole can be restored by re-tightening cut bolts.

This system of construction according to the invention may be built to a high tolerance such that all connected items such as lintels may be built in without having to allow for the normal tolerances associated with traditional construction systems. The prestress of the bolts can be defined and easily checked, thus enabling quality control during construction. Potentially walls constructed with these bricks can be somewhat stronger than an equivalent brick wall; by measuring the bolt prestress, with a torque wrench for instance, the strength of construction can be ascertained with confidence.

The precompression and density of the bricks may also potentially provide good acoustic insulation properties.

Furthermore the building system of the invention is simple and reliable to construct, not needing special bricklaying skills which are presently in high demand. The reduction in mass compared with a standard clay brick or concrete block is also eco-friendly, with low waste ha terms of material use, production and transportation, which together with its ability to be dismantled, is a sustainable system of construction.

The building system of the invention may be applied and used in all manner of ways, for example: in building construction (walls, columns, or piles); for safes or for temporary walls to the side of vehicles and other uses. The bricks may be made from a variety of materials, ea. ceramics materials, glass reinforced concrete, gypsum, steel or aluminium.

The bricks may be laid in an overlapping arrangement in a horizontal plane, three or more layers thick, each layer overlapping the other, forming a beam or slab. In section with the overlap and friction between the brick interfaces three or more layers of bricks would possess "beam" or "slab" flexural section properties through the development of effective tensile and compressive load transfer at the top and bottom layers.

Such an element could span horizontally across a space in the form of a beam or slab. It is also possible to strengthen such an assembly by reinforcing the underside by bonding or bolting on a longitudinal strip, parallel to the span, of material with

high tensile strength. This might for example be steel plate or a lightweight carbon fibre strip, similar to that used for bonding to the underside of concrete structures. Such a floor could alternatively be constructed by prefabrication in a workshop, or on a construction site in situ. If such a floor were to be constructed, the locking bolts on the underside could be utilised to suspend hangers for ceiling construction or mechanical and electrical services, such as conduits or ductwork.

Long bricks could be used for convenience of construction, ea. for lintels or floors, the length being based on a multiple of the standard module.

Cavity walls could be constructed with two single skin walls side by side, and joined at the head, or sill level. In this case no cavity ties would normally be necessary, since the wall construction is superior in strength to a standard masonry wall. Insulation could be inserted easily into such a cavity.

By use of the present invention any construction built using it can be tied together in a robust way owing to the continuity of the locking bolts, with inherent resistance to progressive collapse, earthquake, or otherwise induced ground movements.

In certain circumstances a tight fit between bricks may not be necessary, for example when a wall is built to retain ground for external use, with allowance for some water penetration. In these circumstances the interlocking faces of the brick recess and stud below may be manufactured in such a way that adjacent bricks loosely fit together when assembled. When such loose fitting bricks are assembled, by rotating adjacent bricks relative to each other, a curved plan form to a desired profile may be constructed, prior to tightening the bolts and thereby fixing the structure into place.

Preferred embodiments and features of the invention in its various aspects will now be described in detail, by way of non-limiting examples only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a typical brick with locking bolt as used in the preferred embodiments of the building system according to the invention; Figure 2 is a side elevational, part-sectional, view of a brick assembly forming a structure according to the invention; Figures 3(a) and (b) show, respectively, in top plan view and cross-

sectional side view, an exemplary brick for use in the invention; Figure 3(c) is a top plan view of an example of an assembled wall construction using the system of the invention; Figures 4(a), (b) and (c) show an exemplary locking bolt for use in the system of the invention, shown from, respectively: side elevation, side elevation of the upper socket portion only, and plan view; Figures 5(a) and (b) are part-sectional views of anchor/foundation brick assemblies constructed according to preferred embodiments of the invention; Figures 6(a) and (b) are, respectively, perspective and plan views of a serpentine form of retaining wall construction built using the system of the invention; Figures 7(a) and (b) are, respectively, perspective and cross-sectional views of a box or planter construction built using the system of the invention; Figure 8 is a perspective view of an enclosure with a lid and hinged door built using the system of the invention; and Figures 9(a) and (b) show, respectively, in bottom plan view and cross-

sectional side view, an alternative construction of brick for use in embodiments of the invention.

Referring now to the drawings showing exemplary embodiments of the invention in its various aspects, beginning with Figures 1 to 6 generally:

A wall may be built as follows. Firstly anchor bricks 13 are laid side by side to form the wall outline. One or more rows of bricks 1 are placed in a lapped formation 5 onto the anchor bricks 13, with their recesses 16 locating onto the apernred studs 20. Then bolts 2 are threaded through the vertical passages formed by the hollow studs 20, guided by the exposed, uppermost hollow studs 20. The bolts 2 are then tightened 7 with the desired torque, ea. using a spanner or like tool, into the head 9 of an anchor bolt 12 below, thus clamping the lower part of the wall together.

The number of rows of lapped bricks 1, in each sequential stage of construction, is governed by the length of bolt 4 which will tighten when installed, such that it engages onto the top surface of the uppermost hollow studs 20 and can clamp tightly together the bricks 1 thus installed. This may vary according to the bolt length selected.

The bottommost courses of brick, now clamped together, can be levelled using packs 15. Following this operation cementitious grout can be poured into the foundation recess 17 to cast the bricks 13 onto their foundation base. If desired bricks 13 can be further anchored into the foundations by drilling and fixing grouted or expanding anchors 14 through the hollow studs 20, and into the foundation. Sequentially the bricks may be placed in lapped layers 5, repeating the initial sequence described above. Upon placement of a suitable number of layers of bricks 1 to suit the bolt length, bolts 2 are threaded through the vertical passages formed by the hollow studs 20, and tightened 7 onto the internally threaded heads 9 of pre-tensioned bolts 6, which are embedded in the structure below. By repeating this procedure a wall construction may be built to the required height.

1 1 Note that the faces of the bricks 18 which abut adjoining bricks are flat and orientated perpendicular on plan 22 and in elevation 8 to the top and bottom faces 23, 24 of the bricks. This ensures that bricks abut each other with a tight fit, and hence a high degree of weather tightness. Under exceptional conditions these faces 18 and the top and bottom 23, 24 of the bricks may be treated with a sealing compound for improved weather tightness. The top and bottom faces 23, 24 of the bricks are parallel to each other. This is not essential to the invention but is the most practical form of brick to use in most circumstances.

The side faces of the bricks 18 may be orientated, on plan, so that they are at a variable orientation angle 25 to the alignment 26 of the wall. Based on the standard module 21 the orientation angle 25 may practically range from zero to approximately 30 degrees, but the most commonly adopted orientation is anticipated to be bricks 1 with faces perpendicular 22 on plan, to the line of the wall 26, as this permits the most possible permutations of brick placements. It may be desired to deviate Tom the perpendicular 22 to provide additional interlock between bricks when a wall is required to resist large lateral loads, for instance when used as a ground or water retaining wall.

The exposed side faces, which are visible on the outside of a wall 19, can also be textured or varied in orientation to the alignment of the wall 25 to suit the desired appearance of the wall, on the basis that the location and dimensions of hollow studs 20 and recesses 16 accord with the brick module 21.

It is not necessary to insert bolts 2 into every available hollow stud 20; this may be varied to achieve a desired strength and rigidity of a wall or other structure.

If fewer bolts 2 are to be used than hollow studs 20, then to assist with construction a set pattern of bolts 2 may be placed into colour-coded hollow studs 20. The bricks may be orientated with the inner face, or invisible face following construction, marked to enable the builder to place bricks in the correct orientation. Unused holes in the hollow studs 20 may be used to form

vertical distribution ducts in walls for electrical cables, conduits or plumbing pipes. This is made possible by what is preferably the vertical alignment of the hollow studs 20.

The flexibility and permutations for laying and arranging the bricks are made possible by the dimensioning of the bricks 1, 3 and proportioning of the plan dimensions, and also by the bolts 2, which are fabricated to a specific modular length relative to the bricks' depth. Figure 3 shows by way of example the preferred dimension modules of the brick: Straight bricks 1, 3 are based on a square module 21 of dimension "L/2", indicated as hatched in Figure 3. Brick 3 is of a length equal to one module, "L/2", and brick 1 is of a length equal to two modules, "L". Bricks may be fabricated to any number of modules, but bricks 1, 3 shown in the figures are anticipated to be the most commonly used.

Each brick module 21 of length "L/2" x width "L/2" has four studs located symmetrically within. The hollow studs 20 of outer diameter "L/8" and spaces between are proportioned as multiples of an internal module of "L/ 16"; a fraction of the standard length. It is not essential to the invention that the hollow studs 20 are circular in plan form, but this is the most versatile configuration for ease of construction.

The diameter of the hole in each hollow stud 20 is sized to be slightly greater than the outer diameter of the connecting bolt 2, to allow the bolts to be easily threaded through. Likewise, the recesses 16 on the undersides of the bricks are shaped in outline on plan so that they fit easily onto the outer faces of the hollow studs 20, this being a square of dimension fractionally larger than "3L/8", with corner fillets with radii fractionally larger than "L/ 16". The recess 16 in each brick should preferably be fractionally greater than the boundary

transcribed by the hollow studs 20 to allow a tight fit, but not so tight as to require bricks to be forced onto one another when laid.

As an alternative to the recess 16, bricks 1 may be fabricated by forming four holes in each module 21 on the underside 24 of each brick 1 positioned in exact accordance with the plan position of the four hollow studs 20 in each module 21 on the upperside 23 of the bricks. If these holes are fractionally greater in diameter than the hollow studs 20, and in depth fractionally greater than the depth of a hollow stud 20 plus bolt head 9, each brick thus fabricated may be positioned in a structural assembly in exactly the same way as that achieved with bricks 1 with a single recess 16 in its underside 24.

Thus a preferred embodiment of brick in accordance with the invention is shown with recesses 16, as this is superior in terms of portability and reduced weight, although under certain circumstances the alternative brick may be selected for its greater density and strength.

In the preferred system of the invention locking bolts 2 are fabricated to a length 4 which is a multiple of the brick depth, plus whatever dimension is practically required for fixing. This enables full engagement, such that the tip of the shaft of the bolt 2 tightens 7 onto the head 9 of a brick 1 below. The head of each bolt 9 is dimensioned to allow sufficient thread for tightening the threaded bolt shaft 1 1 above, but short enough to sit within the upper brick recess 16 without touching the underside of the upper brick face. An optional taper 10 is shown at the top end of the internal thread, to facilitate initial engagement. The head 9 of the bolt 2 may preferably be hexagonal, with outer dimensions wide enough to engage onto the top surface of a hollow stud 20, but no greater than the outer diameter "L/8" of the hollow stud itself. Washers may be used

under the head 9 if required; this would not compromise the principles of the invention. Another possible application of the brick assembly in certain circumstances is to allow for a looser fit between bricks 1. The end faces 18 of a brick may be fabricated so that the dimension between the end face and outer face of adjacent hollow studs 20 is marginally less than "L/ 16". Thus fabricated, this would create a gap between bricks 1 when laid together to form a structure.

Furthermore the recesses 16 on the underside of the bricks 24 could be shaped in outline with a square of dimension larger than "3L/8" with corner fillets with radii larger than "L/ 16" with a clearance from the outer faces of hollow studs 20 less than equal to half the gap between two adjacent bricks. An alternative form of brick, as described previously with holes in lieu of a recess 16, may achieve the same end if the holes are larger than the hollow studs 20 by a clearance 27 equal to half the gap between bricks.

The clearance between hollow studs 20 and recesses 16, or alternative holes as described previously, can allow the wall plan form to be adjusted to a serpentine shape 28 to a desired formation by rotating adjacent bricks 1 relative to each other on plan, prior to tightening the bolts 2. Varying the gap and clearance of the recess 16, or alternative holes, from the hollow studs 20, allows variation in the curvature which may thus be formed. This application would be appropriate where the gap between adjacent bricks is not critical to achieve a weathertight structure, such as on a ground retaining wall which allows water seepage through the bricks.

Using the principles of this invention bricks may be constructed in a variety of shapes. For instance, if the brick is curved on plan, the principle of the above module 21 is maintained. It is noted that the inner radius and outer radius inscribed through the centreline of the hollow studs 20 will be a different

dimension. The hollow studs 20 would remain a standard size and the gaps between and at the edge could vary to suit the radius inscribed through the respective hollow studs 20.

Figure 7 shows an example of a structure such as a box or planter built using the system according to preferred embodiments of the various aspects of the invention. In this example, however, additional (ea. cylindrical) spacer elements 30 placed around the locking bolts may be used as necessary to help support the bricks as the structure is built.

Figure 8 shows an example of another structure built using the system according to preferred embodiments of the invention, but which additionally incorporates a hinged door 40 and a flat, ea. wooden, deck 50 which is secured to the top of the main wall structure by means of screws or bolts which fit into the remaining free head sockets of the locking bolts.

Figures 9(a) and (b) show an example of an alternative form of brick 1' for use in embodiments of the invention, which doesn't have walls which themselves define the internal recessed or hollowed out section on its underside, but instead has a larger general hollowed out underside, with the side walls 56 of the brick 1' being relatively thin, ea. only of a millimetre or two, but with the recessed or hollowed out underside 54 being formed with a plurality of inwardly extending rib, fin and/or buttress supporting elements 58, 60 which define the internal dimensions which substantially match or are slightly greater than the corresponding external dimensions of the studs on the top of a like brick which are to be located therein in the building of the structure. These supporting elements 58, 60 may preferably further include stiffening elements 70 formed below each apertured stud (as shown in Figure 9(b)) for added strength of the brick structure.

It is to be understood that the above description of preferred embodiments and

features of the various aspects of the invention has been by way of nonlimiting examples only, and various modifications may be made from what has been specifically described and illustrated whilst remaining within the scope of the invention as claimed.

Claims

_LAIMS

1. A system for building a structure, comprising: a plurality of bricks, each brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure; and a plurality of locking bolts, each comprising a threaded shaft and a head section including a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure.

2. A method of building a structure, comprising: providing a plurality of bricks, each brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure; providing a plurality of locking bolts, each comprising a threaded shaft and a head section including a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure; and placing said bricks adjacent one another in sequential courses of said structure, each said course being secured to the course below by means of said locking bolts being inserted through selected ones of said apertured studs in the bricks and clamped into the head section of a corresponding locking bolt in the adjacent course therebelow.

3. A brick for use in building a structure, the brick having one or more recesses in its underside and a plurality of studs protruding upwardly from its upperside for location within at least a portion of the recess(es) in the underside of at least one other like brick placed thereupon in the building of said structure, wherein each stud has an aperture extending therethrough to the brick's recessed underside for accepting a locking bolt therethrough for clamping of one said brick to another in an above or below course of said structure.

4. A brick according to claim 3, wherein the recessed underside is formed with a single generally square or rectangular recess or hollowed out section, the internal dimensions of which substantially match or are slightly greater than the corresponding external dimensions of the studs on the top of a like brick which are to be located therein in the building of the structure.

5. A brick according to claim 3, wherein discrete recesses or holes are provided in the underside thereof to accommodate individual respective studs on the top of a brick in the course below in said structure.

6. A brick according to any one of claims 3 to 5, wherein the studs on the top of the brick are configured in a symmetrical array such as to substantially match the size and shape of at least a portion of the recess(es) in the underside of at least one other like brick, such that the bricks in adjacent courses of the structure can be located and anchored one above another by virtue of the studs in the top of one brick locating within the recess(es) in the underside of at least one other like brick.

7. A brick according to claim 4, which is formed with thin external walls and wherein the recessed or hollowed out underside is formed with a plurality of inwardly extending rib, fin and/or buttress supporting elements which define the said internal dimensions which substantially match or are slightly greater than the

1') corresponding external dimensions of the studs on the top of a like brick which are to be located therein in the building of the structure.

8. A locking bolt for rise in building a structure comprising a plurality of courses of bricks, the bolt comprising a threaded shaft and a head section including a threaded socket for accepting an end portion of the shaft of a like locking bolt in an above course of the structure.

9. A locking bolt according to claim 8, wherein its head section is externally shaped for rotational clamping with a tool.

10. A structure built using the system according to claim t or the method according to claim 2.

1 1. A structure according to claim 10 which is a wall.

12. A system for or a method of building a structure, or a brick or a locking bolt for use therein, substantially as described herein with reference to any of the accompanying drawings.