IMPROVEMENTS IN AND RELATING TO BUILDING BLOCKS

Abstract: A building block (20) of chevron shaped uniform transverse section with a hollow core (33). A dovetail nib (26) and complimentary recess (32) are respectively located centrally about the apexes (29 and 30) of the inverted V-shaped upper and lower surfaces (25 and 31). The recess (32) opens into the hollow core (33). By sliding the nib (26) of one block within the recess (32) of a like block stable wall structures can be formed without the need for mortar. Such structures can be provided with additional mass by filling the internal voids formed between adjoining blocks with granular material as construction proceeds. Blocks with sides (23 and 24) of equal height build into planar structures. Blocks with sides of unequal height build into planar structures when adjoining blocks are disposed at 180 degrees to each other and build into curved or stepped face structures when all blocks are similarly disposed.

Description: IMPROVEMENTS IN AND RELATING TO BUILDING BLOCKS This invention concerns improvements in and relating to building blocks. An object of the present invention is to provide a voided building block with a uniform transverse section which can be produced by conventional extrusion and pressing processes and which allows like blocks to interlock without requiring a bonding agent. A further object of the present invention is to provide a building block that can be used to construct structures of variable alignment wherein internal voids can be filled with granular material as construction proceeds. Such structures include free standing walls, retaining walls and facings to reinforced soil embankments and have blocks disposed in substantially horizontal courses with vertical joints between units in adjacent courses offset one to the other and blocks disposed in substantially vertical columns with horizontal joints between units in adjacent columns offset one to the other. Interlockable precast concrete blocks and bricks of uniform transverse section are known in a variety of shapes to suit particular building purposes. Such blocks are in general provided with a projection and corresponding recess in opposed bearing surfaces. Blocks and bricks wherein the width of the projection is constant or decreases outwardly from the adjacent bearing surface link together by placing one block on top of a like block so that the nib of the one fits into the recess of the other. The joint thus formed can resist lateral displacement only. Blocks and bricks wherein the width of the projection increases outwardly from the adjacent bearing surface link together by axially projecting the nib of one block into the recess of a like block. Such joints are sometimes referred to as dovetail joints and resist both lateral and vertical displacement. For instance, interlocking building blocks with a uniform transverse section are known from German Patent DE 29 21 489, United States Patent 4,490,075, and UK Patent 827,508 and each has corresponding projections and grooves in opposed bearing surfaces wherein like blocks interlock by placing one block on top of another. Such blocks can readily be removed from any structure constructed therefrom unless a bonding agent is introduced within the joints. Building bricks are also known from UK Patent 540,561 wherein a solid brick is provided with a centrally located dovetailed projection in its upper bearing surface and a corresponding dovetailed groove in its lower bearing surface which bearing surfaces are slightly inclined downwardly to the outermost surfaces thereof for drainage purposes only. Bricks and blocks are also known from UK Patent 635,159 wherein a brick or block of trapezoidal transverse section is provided with a dovetailed projection and recess respectively within opposed beanng surfaces and wherein the projection is substantially smaller than the recess thus requiring mortar to achieve a strong joint The dovetailed projections and the grooves and recesses hitherto referred to each has side surfaces acutely angled to the adjacent bearing surface Like bricks or like blocks interlock when the projection of one is located within the recess of another and stability of any structure constructed therefrom is largely dependent on the strength of the interlocking joints The acute angled dovetail joints are more difficult to form, are more prone to accident damage and are relatively weaker than joints wherein the side surfaces are normal or near normal to the adjacent bearing surface According to the present invention there is provided an axially extending building block of chevron shaped uniform transverse section comprising two vertical end surfaces, two vertical side surfaces, a hollow core, an inverted V-shaped upper surface and a correspondingly angled, inverted V-shaped lower surface, wherein the upper surface is provided with a nib centrally located and symmetrical about the apex of the upper surface and which nib has two side faces each projecting substantially normal to the said upper surface and the lower surface is provided with a recess of complimentary shape to the nib in the upper surface and which opens into the hollow core whereby on engagement of the nib of one block within the recess of another like block, the blocks interlock together and provide a wall structure with an axially extending hollow core The building block, according to one aspect of the present invention, is characterised in that the chevron shaped section of the block is symmetrical about its principal vertical axis such that engagement of the nib of one block within the recess of a like block similarly oriented or rotated 180 degrees about its vertical axis results in a wall structure with aligned side surfaces The building block, according to another aspect of the present invention, is characterised in that the side surfaces are of unequal height equally disposed about the principal horizontal axis and the apexes of the correspondingly angled higher and lower inverted V-shaped surfaces are centrally located within the said surfaces and are equally offset from the principal vertical axis towards the lower and higher side surfaces respectively such that on engagement of the nib of one block within the recess of a similarly oriented and like block a wall structure is formed with radial side surfaces and on engagement of the nib of one block within the recess of a like block rotated 180 degrees about its pnncipal vertical axis a wall structure is formed with aligned side surfaces The building block, according to another aspect of the present invention, is characterised in that the vertical side surfaces are of unequal height equally disposed about the pnncipal horizontal axis and the apexes of the correspondingly angled upper and lower inverted V-shaped surfaces are equally offset from the principal vertical axis towards the higher and lower side surfaces respectively such that on engagement of the nib of one block within the recess of a similarly oriented and like block a wall structure is formed with stepped side surfaces and on engagement of the nib of one block within the recess of a like block rotated 180 degrees about its principal vertical axis a wall structure is formed with aligned side surfaces According to another aspect of the invention the building block is characteπsed in that at least one end surface is provided with two aligned truncated wedge shaped channels which outwardly increase in depth from the core of the block and are normal to and open into opposed side surfaces The accompanying drawings show by way of example various forms of block and wall structures which can be constructed using blocks in accordance with the invention and wherein - Figures 1 , 5 and 10 show transverse sections of three forms of a block according to the invention, Figure 2 is an end elevation of four blocks of shape as in Fig 1 linked together to conform to a straight alignment, Figures 3 and 4 show in perspective, views of a block of shape as in Fig 1 viewed in upπght and inverted orientation respectively, Figures 6 and 7 are plan views of four blocks of shape as in Fig 5 linked together to conform to a straight and to a radial alignment respectively, Figures 8 and 9 show perspective views of a block of shape as in Fig 5 viewed with the block on opposed ends and rotated through 180 degrees one to the other about the principal vertical axis of the block, Figures 11 and 12 are plan views of four blocks of shape as in Fig 10 built to conform to a stepped and to a vertical alignment respectively, Figure 13 is a perspective view of a block of shape as in Fig 10 viewed with the block on end, Figure 14 is a part sectional view through a revetment constructed from blocks of shape as in Fig 5 and wherein an earth embankment is supported by a facing of blocks tied back into the earth, Fιgure15 is a perspective view of a wall structure constructed from blocks of shape as in Fig 5 with aligned wedge shaped channels as in Figs 8 and Fig 9 wherein reinforcement straps are securely fixed within the said channels and extend into the backfill to the structure, Figure 16 is a perspective view of a wall structure constructed from blocks of shape as in Fig 5 wherein the blocks are disposed in substantially horizontal courses with vertical joints between blocks in each course offset from the vertical joints between blocks in adjacent courses, and Figure 17 is a perspective view of a wall structure constructed from blocks of shape as in Fig 5 wherein the blocks are disposed in substantially vertical columns with horizontal joints between blocks in each column offset from the horizontal joints between blocks in adjacent columns The block 20 is of uniform transverse section and has opposed parallel end faces 21 and 22 and parallel side surfaces 23 and 24 The said side surfaces are of rectangular form and are normal to the end faces. The inverted V-shaped upper surface 25 is provided with a nib 26 centrally located about the apex 29 of the upper surface and which nib has side faces 27 each projecting substantially normal to the said upper surface. The inverted V-shaped lower surface 31 is provided with a recess 32 of complimentary shape to the nib 26 This recess is centrally located about the apex 30 of the lower surface and is further extended into the block thus to provide aπ internal void 33 The block has a principal vertical axis 28 which is parallel to and equidistant from the side surfaces 23 and 24 and has a principal horizontal axis 35 which is normal to and bisects the said side surfaces A reference line 36 (shown dashed) passes through the points of intersection 37 and 38 of the upper surface 25 with the side surfaces 23 and 24 respectively Correspondingly a reference line 39 (shown dashed) passes through the points of intersection 40 and 41 of the lower surface 31 with the side surfaces 23 and 24 respectively The reference lines 36 and 39 are parallel as shown in Fig 1 or converge and intersect at a point 34 on the principal horizontal axis 35 as shown in Fig 5 and Fig 10 Blocks according to any aspect of the invention can be extruded or moulded using concrete, clay or any such extrudable or mouldable material and can be used in any oπentation suitable for the purpose in hand Blocks can be provided with either one or both side faces having an exposed aggregate finish achieved by moulding or extruding two or more units together with like sides j oined and thereafter cleaving the multiple unit Side surfaces can also be provided with ribbed or other decorative features Figures 1 , 2, 3 and 4 refer to one form of the invention wherein the block 20 has a uniform transverse section symmetrical about the principal vertical axis 28 which passes through the apex 29 of the upper surface 25 and through the apex 30 of the lower surface 31 The sides 23 and 24 are of equal height and are equally disposed about the principal horizontal axis 35 Blocks link together by locating the nib 26 of one block 20 within the recess 30 of an adjacent block 20 of like orientation or rotated through 180 degrees about the principal vertical axis 28 resulting in a structure as per Fig 2 wherein the sides of adjacent blocks are aligned Figures 5, 6, 7, 8 and 9 refer to a form of the block 20 which has an asymmetrical uniform transverse section and wherein the sides 23 and 24 are of unequal height equally disposed about the pnncipal horizontal axis 35 The apex 29 of the upper surface 25 is offset from the pnncipal vertical axis 28 towards the lower side 23 and the apex 30 of the lower surface 31 is equally offset towards the higher side 24 By engaging the nib 26 of one block within the recess 30 of an adjacent block of like oπentation a structure is formed as in Fig 7 wherein the sides of adjacent blocks follow a curved alignment By locating the nib 26 of one block 20 within the recess 30 of an adjacent block 20 rotated 180 degrees about its principal vertical axis 35 a structure is formed as in Fig 6 wherein the sides of adjacent blocks are aligned Figures 10, 11 , 12 and 13 refer to a form of the block which has an asymmetπcal uniform transverse section wherein the sides 23 and 24 are of unequal height equally disposed about the pnncipal horizontal axis 35 The apex 29 of the upper surface is offset from the principal vertical axis 28 towards the higher side 24 and the apex 30 of the lower surface 31 is equally offset towards the lower side 23 By engaging the nib 26 of one block within the recess 30 of an adjacent block of like oπentation a structure is formed as in Fig 1 1 wherein the sides of adjacent blocks follow a stepped alignment By locating the nib 26 of one block within the recess 30 of an adjacent block rotated 180 degrees about its principal honzontal axis 35 a structure is formed as in Fig 12 wherein the sides of adjacent blocks are aligned The block apex angle is defined as the angle formed between the outwardly sloping elements of the inverted V-shaped upper surface 25 and is equal to the angle formed between the outwardly sloping elements of the inverted V-shaped lower surface 31 Consider two like blocks on end The blocks link together by aligning the nib 26 of one block with the recess 32 of the other and then moving one block in a downward vertical direction so that the said nib 26 and recess 32 engage The mechanical joint thus formed prevents lateral displacement of one block relative to the other To allow for casting and construction tolerances the throat width of the nib is preferably slightly less than that of the recess The block angle is typically between 90 and 140 degrees and together with the height of the sides 27 to the nib 26 determines the difference in width between the throat and the head of the dovetail joint The shape of the upper surface(s) of the nib 26 is preferably domed but may be varied to suit manufacturing or design preferences The block is provided with a hollow core 33 which may extend as little as 3mm inwardly from the head of the dovetail recess 32 thus to ensure clearance to the nib of a linked block but preferably should occupy at least 15% of the block volume so that a useful saving in block weight may be achieved The hollow core preferably should have a width not greater than the head width of the recess 32 and should extend inwardly to the pnncipal horizontal axis 35 at least The void which is formed when two like blocks are linked together may be filled with bound or loose aggregate dunng construction of a structure thus to provide additional mass for the structure and to provide anchorage for slotted earth reinforcement straps The relative heights of the sides of a block and the width of the block determine the angle by which one block is rotated relative to the other when two like blocks similarly oriented are linked together For example, similarly oriented blocks of width 250mm with sides of heights 165mm and 209mm will be rotated by 10 degrees one to the other when linked together and 36 such blocks will thus form a cyhndπcal shaped structure with an external radius of 1 2m In reinforced soil wall construction soil reinforcement fabric or mesh layers may be sandwiched between honzontal courses of blocks or tied to straps anchored between ends of blocks forming vertical columns of blocks Referring to Fig 15, a part structure constructed using blocks as in Fig 8 and Fig 9 has straps 43 of polymer or other suitably strong and durable material anchored within the structure by locating a strap with a locally thickened end within the channel 42 formed in one end of the block and drawing it into the wedge shaped recess which results when two like blocks are axially aligned and abut each other In a column type structure the ends of lengths of fabric or mesh of uniform width may be anchored within vertical block joints one or more column widths apart thus providing pockets behind the wall face which can be filled with free draining granular material as construction of the wall proceeds to give the wall structure increased stability In coursed wall construction blocks can be used with the recess 32 upward or downward facing and with blocks in courses abutting or spaced apart by an amount preferably not greater than three quarters of a normal block length. Special recess closure blocks 44 can be provided so that a horizontal base can be formed more readily for a coursed wall structure such as shown in Fig.16 or to form a square end to a column type structure such as shown in Fig. 17. Special blocks 45 can also be provided so that a horizontal cope can be formed to a coursed wall structure such as shown in Fig.16 or to form a square end to a column type structure such as shown in Fig.17. Blocks can be provided in different lengths as required for the purpose in hand. Blocks of half normal block length can be used to provide a break in bond between adjacent courses or columns in a wall structure as shown in Figs.16 and 17 respectively. Construction blocks according to the invention are extremely versatile and can be used in any application by unskilled labour.

Claims: CLAIMS 1 A building block of chevron shaped uniform transverse section which block comprises two end surfaces, two side surfaces, an inverted V-shaped upper surface and a complimentary, inverted V-shaped lower surface and is characterised by a dovetail nib and corresponding recess respectively located centrally about the apexes of the upper and lower surfaces and by the said recess opening into a hollow core 2 A voided building block of chevron shaped uniform transverse section comprising two end surfaces, two side surfaces, an inverted V-shaped upper surface and a correspondingly angled inverted V-shaped lower surface, characterised by a dovetail nib with two side faces equally displaced on either side of the apex and projecting substantially normal to the said upper surface, and by a recess in the lower surface of complimentary shape to the nib in the upper surface and which opens into a hollow core whereby on engagement of the nib of one block within the recess of another like block similarly oriented or rotated through 180 degrees the blocks interlock together and provide a wall structure with an axially extending hollow core 3 A building block as claimed in Claims 1 and 2 characteπsed by the apexes of the upper and lower surfaces being on the pnncipal vertical axis such that engagement of the dovetail nib of one block according to the invention within the complimentary recess of a like block similarly oriented or rotated through 180 degrees about its vertical axis results in a wall structure wherein the sides of blocks are aligned 4 A building block as claimed in Claims 1 and 2 characteπsed by having vertical side surfaces of unequal height each bisected by the principal horizontal axis and wherein the apex of the upper surface and the apex of the lower surface are equally offset from the principal vertical axis towards the lower side and towards the higher side respectively such that on engagement of the nib of one block within the recess of a similarly oriented and like block a wall structure is formed which fits a stepped alignment and on engagement of the nib of one such block within the recess of a like block rotated 180 degrees about its pnncipal vertical axis a wall structure is formed which fits a straight alignment 5 A building block as claimed in Claims 1 and 2 characteπsed by having vertical side surfaces of unequal height each bisected by the principal horizontal axis and wherein the apex of the upper surface and the apex of the lower surface are equally offset from the principal vertical axis towards the higher side and towards the lower side respectively such that on engagement of the nib of one block within the recess of a similarly oriented and like block a wall structure is formed which fits a stepped alignment and on engagement of the nib of one such block within the recess of a like block rotated 180 degrees about its principal vertical axis a wall structure is formed which fits a straight alignment 6 A building block as claimed in Claims 3, 4 and 5 characterised by having at least one end surface provided with two aligned truncated wedge shaped channels each outwardly increasing in depth from the core of the block and normal to and opening into the opposed side surfaces thus providing a recess for anchoring polymer ties, straps or other such fixings for reinforced soil structures 7 A building block as claimed in Claims 3, 4, 5 and 6 characterised by either one or both side faces having an exposed aggregate finish achieved by moulding or extruding two or more units together with like sides joined and thereafter cleaving the multiple unit 8 A building block as claimed in Claims 3,4,5 and 6 characterised by either one or both side faces having πbbed or other decorative features 9 A building structure constructed using a plurality of blocks according to the invention characteπsed by the blocks being built in substantially horizontal courses and having vertical joints between blocks in adjacent courses latterly offset one to the other 10 A building structure constructed using a plurality of blocks according to the invention characteπsed by the blocks being built on end in substantially vertical columns and having the honzontal joints between blocks in adjacent columns vertically offset one to the other 11 Building blocks constructed substantially as descnbed herein with reference to Figures 1-17 of the accompanying drawings

Inventors: CLARK LYNDA SUSAN, CLARK MICHAEL DAVID, CLARK, LYNDA, SUSAN, CLARK, MICHAEL, DAVID
Applicants: CLARK LYNDA SUSAN, CLARK MICHAEL DAVID, CLARK, LYNDA, SUSAN, CLARK, MICHAEL, DAVID
Application year: 1997
Main classification: E04B2
IPC codes: E04B2