[0001] This invention concerns improvements in and relating to building blocks.
[0002] An object of the present invention is to provide a building block which permits,
without the use of a bonding agent between courses, the construction of free-standing
walls which offer full or partial screening and the construction of retaining walls
which have a stepped exposed face.
[0003] Economy in the construction of mass gravity and crib retaining walls results when
the walls are stepped or battered back against the material to be retained to such
an extent that the resultant compressive stress over any transverse section of a wall
is uniform. A fully screened free-standing wall can be constructed by building concrete
blocks or the like in courses with each block abutting. By providing gaps between
blocks and/or by providing blocks with throughgoing orifices between exposed faces
such a wall may become more decorative and less resistant to wind forces but offers
less screening. Precast concrete blocks of various forms are currently used to construct
retaining walls and screen walls and although cement mortar is commonly used to provide
a bond between adjacent courses of blocks, other forms of block exist which are provided
with suitably formed nibs and recesses so that a mechanical interlock is achieved
between blocks. Hitherto more than one form of block has been required to construct
dry bound free-standing screen walls and retaining walls.
[0004] Building blocks are known from U.K. Patent 2000830B wherein the upper side of the
block has a bearing surface which constitutes a peaked roof shape and a lower bearing
surface which constitutes a recess complementary to said peaked roof and in which
the upper side is wider than the lower side so that the upper side of one block projects
beyond the respective lower side of another of said blocks resting thereon. Such blocks
however are limited to the construction of stepped retaining walls.
[0005] The building block, according to one aspect of the present invention is characterised
in that the upper and lower surfaces each have a bearing surface of equal width, the
upper bearing surface having an extension thereof extending to the front face of the
block and the lower bearing surface having an extension thereof extending to the rear
face of the block whereby one block can be placed upon another block in like disposition
so that the front extension of the lower block extends beyond the upper block or in
a disposition at 180° to each other in which the front face of one block is vertically
alligned with the rear face of the other block, and the width of each bearing surface
and its extension is equal to that of the other bearing surface and extension.
[0006] The building block according to another aspect of the invention is characterised
in that the front face and the rear face each have a horizontal upper edge vertically
disposed to a lower edge, the upper surface is sub-divided into a narrow edge strip
extending horizontally from or inclined to the upper edge of the block and a wide
bearing surface extending therefrom to the upper edge of the rear face and which surface
is provided with a centrally located projection with a vertical axis of symmetry,
the lower surface is correspondingly sub-divided into a narrow edge strip extending
horizontally from or similarly inclined to the lower edge of the rear face of the
block and a wide bearing surface extending therefrom to the lower edge of the front
face and provided with a centrally located recess of complementary shape to the projection
on the upper face, and which recess has a vertical axis of symmetry which is displaced
from that of the projection by the width of the narrow edge strip.
[0007] The invention also comprises a free-standing vertical wall structure constructed
using a plurality of such blocks in an alternating course sequence consisting of a
course of blocks each laid with its front face exposed, superimposed on a course of
blocks each laid with its rear face exposed or vice versa when viewed from either
side of the structure.
[0008] The invention further provides a retaining wall structure constructed using a plurality
of such blocks in a course sequence consisting either of a course of blocks each laid
with its front face exposed, superimposed on a like course of blocks or on an odd
number of courses in which every odd course consists of blocks each with its front
face exposed and every even course consists of blocks each with its rear face exposed.
[0009] The accompanying drawings show by way of example various forms of block and types
of wall structure which can be constructed using blocks in accordance with the invention
and wherein:-
Figures 1 and 2 are elevations on one end and Figures 3 and 4 are elevations on the
other end of four altemative shapes of a block according to the invention;
Figures 5 and 6 are perspective views of a block of shape as in Fig. 1 in upright and in inverted orientation respectively;
Figures 7 and 8 are perspective views of three blocks of shape as in Fig. 1 built
to form a vertical sided column by reversing the orientation of alternate blocks and
built to form a stepped structure using units of like orientation respectively;
Figures 9, 10, 11 and 12 correspond to Figs. 5, 6 7 and 8 respectively but relate
to a block of shape as in Fig. 3;
Figure 13 is a perspective view of part of a free-standing wall built using blocks
of shape as in Fig.3 and which wall is of open or partially screened form in the upper
courses and is of closed form in the lower courses; and
Figure 14 is a perspective view of part of a retaining wall built using blocks of
shape as in Fig. 3.
[0010] Referring to the drawings in general, the blocks may be moulded using concrete or
any such mouldable material and may also be produced by extrusion using semi-dry mix
concrete, asphalt, or the like.
[0011] The block is of uniform transverse section and has opposed vertical end faces 11
and 12 of reflected form. The front face 13 and the rear face 14 may be vertical,
concave, convex, ribbed or otherwise shaped but the upper edge 15 of front face 13
and the upper edge 16 of rear face 14 are horizontal and are vertically disposed to
their corresponding lower edges 17 and 18 respectively.
[0012] Referring now to Figs. 1 to 4, the upper surface of the block is divided into a narrow
edge strip 19 and a wide bearing surface 20 each extending over the length of the
block. The wide bearing surface 20 extends horizontally from the upper edge 16 of
the rear face 14 and occupies at least two thirds of the overall width of the block.
The narrow edge strip 19 extends either horizontally Figs. 1, 2 and 4 from or is inclined
(Fig. 3) to the upper edge 15 of the front face 13 and respectively connects to or
intersects with the wide bearing surface 20 and occupies not more than one third of
the overall width of the block. The width of the narrow edge strip 19 is related to
the depth of the front face 13 and determines the slope of the exposed face of a retaining
wall constructed using a plurality of the blocks. The wide bearing surface 20 is provided
with a projection 21 which may occupy all (Fig. 3) or only part of the width (Figs.
1, 2 and 4) of the bearing surface 20. The projection 21 is of any regular cross-sectional
shape which has horizontal base, an imaginary 21' and a vertical axis of symmetry
22 such as a rectangle (Fig. 1), an isosceles triangle (Figs. 2 and 3), or a right
circular arc (Fig.4).
[0013] The lower surface of the block is correspondingly shaped to that of the upper surface
rotated horizontally through one half of one revolution and consists of a narrow edge
strip 23 and a wide bearing surface 24 each extending over the length of the block.
The narrow edge strip 23 has similar dimensions to those of the upper surface edge
strip 19 and extends either horizontally from the lower edge 18 of the rear face 14
or is inclined to the vertical plane containing the upper edge 16 and the lower edge
18 of the rear face 14 or is inclined to the vertical plane containing the upper edge
16 and the lower edge 18 of the rear face 14 at the same angle as the upper edge strip
19 is inclined to the vertical plane containing the upper edge 15 and the lower edge
17 of the front face 13. The wide bearing surface 24 is the same width as the upper
surface wide bearing surface 20 and extends from the lower edge 17 of the front face
13 and respectively connects to or intersects with the horizontal or inclined narrow
edge strip 23. The wide bearing surface 24 is provided with a recess 25 of dimensions
which correspond to those of the upper surface projection 21 and which recess has
an imaginary base 25' and a vertical axis of symmetry 26 horizontally displaced from
the vertical axis of symmetry 22 of the projection by a distance equal to the plan
width of the narrow edge strip 19 in the upper surface. This is also the plan width
of the narrow edge strip 23 in the lower surface.
[0014] Referring in particular to Fig. 3 there is shown a block in which the upper surface
20 comprises two substantially planar bearingsurfaces 20A, 20B disposed at an angle
to each other to constitute a peaked roof shape 21 with a vertical axis of symmetry
22 and an extention 19 extending from the bearing surface 20B to the front face 13
of the block. The lower bearing surface 24 similarly comprises two substantially planar
bearing surfaces 24A, 24B, disposed at an angle to each other to form a recess 25
complementary to the peaked roof shape 21 with a vertical axis of symmetry 26 and
an extension 23 extending from the bearing surface 24B to the rear face 14. The axis
of symmetry 22 and 26 are displaced laterally to each other by the width of the extension
19/23 and equally from the central longitudinal axis of the block.
[0015] The upper planar surface 20A is equal in length to the lower planar surface 24A and
the length of the upper planar surface 20B and its extension 19 is equal to the length
of the lower planar surface 24B and its extension 23. The depth of the rear end face
14 is greater than that of the front face.
[0016] Referring now to Figs. 5 to 12, when a block is superimposed on a corresponding block
in reversed orientation then the lower surface of the upper block bears fully on the
upper surface of the lower block and is such that the projection 21 of the lower block
nests into the recess 25 in the upper block and the upper surface narrow edge strip
19 of the lower block is in full contact with the lower surface narrow edge strip
23 of the upper block. This is illustrated in Figs. 7 and 11 wherein three blocks
alternating in orientation and each with a transverse section as shown respectively
in Figs. 1 and 3, are built one on top of another thus to form a column with vertical
sides.
[0017] When a block is superimposed on a corresponding block of like orientation as shown
in Figs. 8 and 12 then the wide bearing surface 24 on the lower surface of the upper
block bears directly on the wide bearing surface 20 of the lower block such that the
recess 25 in the lower surface of the upper block provides a snug fit for the projection
21 on the upper surface of the lower block. The upper block is thus laterally displaced
relative to the lower block and causes the narrow edge strip 19 of the upper surface
of the lower block to be exposed.
[0018] Fig. 13 shows a free-standing wall structure constructed using blocks with a transverse
section as shown in Fig. 3. Blocks in successive courses of the wall alternate in
orientation thus providing a wall with vertical sides. In the lower four courses of
the wall the blocks in any course abut to give a closed face appearance whereas in
the next five courses, blocks in any course are set less than a block length apart
so that blocks in the next course span the gaps thus formed giving an open face appearance.
In the top course of the wall each block abutts the adjacent block thus to form a
continuous cope.
[0019] Fig. 14 shows a part-sectional perspective view of a retaining wall structure constructed
using blocks with a transverse section as shown in Fig. 3. The lowest or foundation
course of blocks consists of blocks laid contiguously to permit a relatively even
transfer of load to the subsoil or to an in-situ concrete foundation. The top course
or coping course of blocks likewise has blocks laid contiguously as this is preferable
both aesthetically and for protection of the wall interior from the affect of weather.
As a measure of protection against the removal of blocks in the coping course of such
a wall by vandals, the backfill material 27 can usefully be placed to cover over the
rearward portion of a block up to the level of the upper surface projection 21. Blocks
in each of the intermediate courses of the retaining wall are either laid contiguously
or may be spaced apart depending on the weight of wall required to counteract the
pressure from the retained material 28. In a retaining wall of varying height blocks
in any course may require to be closely spaced or abutting for high sections and spaced
relatively further apart over low sections thus providing more economical use of blocks.
After laying each course of blocks in a retaining wall the void behind the blocks
is infilled with suitable material fill 27 up to the level of the upper edge of the
rear face of the blocks and the fill material spills over the exposed upper surfaces
of blocks in the superimposed course at least as far as the top of each block projection
21 thus giving additional weight to the wall structure.
[0020] By laying two or more courses of blocks in like orientation side by side such that
the rear faces 14 of blocks in one course abut with the front faces 13 of blocks in
an adjacent course, walls can be constructed of increased width to cater for locations
requiring higher walls and for walls with increased resistance against overturning
and sideways displacement. To ensure that a wall of multiple block width acts as a
composite wall and to inhibit differential vertical displacement of adjacent courses
of units, a flexible synthetic sheeting material 29 can be placed between adjacent
courses of units to reinforce the vertical joints.
[0021] By choosing block dimensions such that the height of the projection 21 is equal to
or greater than the mean height of the front face 13 and the rear face 14 then even
an 'open' faced wall built with such blocks will provide full visual screening although
permitting passage of wind.
[0022] Blocks can usefully be provided with an extending orifice in order to locate steel
bars, rope, cable or the like which can be used to reinforce courses of blocks, assist
handling of the blocks and to 'lock' adjacent blocks together as is preferable in
a wall cope.
[0023] Although blocks according to the invention are normally used in upright orientation
they may be oriented in any manner suitable for the purpose in hand. Indeed inverted
blocks of transverse section as shown in Fig. 3 can be used to form surface water
drainage channels and cascades.
[0024] Construction blocks according to the invention are extremely versatile and unskilled
labour can be used in any application thereof. Any structure built using the blocks
may require blocks of different lengths to form vertical ends to the structure consistant
with the provision of staggered vertical joints between adjacent courses.
1. A building block of uniform asymmetric transverse section comprising two vertical
end faces, a front face and a rear face and upper and lower surfaces characterised
in that the upper and lower surfaces each have a bearing surface 20, 24 of equal width,
the upper bearing surface having an extension thereof 19 extending to the front face
13 of the block and the lower bearing surface having an extension 23 thereof extending
to the rear face 14 of the block whereby one block can be placed upon another block
in like disposition so that the front extension 19 of the lower block extends beyond
the upper block or in a disposition at 180° to each other in which the front face 13 of one block is vertically alligned with
the rear face 14 of the other block, and the width of each bearing surface 20 or 24
and its extension 19 or 23 is equal to that of the other bearing surface and extension.
2. A building block of uniform asymmetric transverse section comprising two vertical
end faces, a front face and a rear face and upper and lower surfaces, characterised
in that the front face 13 and the rear face 14 each have a horizontal upper edge 15 and 16 vertically disposed to a lower edge 17
and 18, the upper surface is subdivided into a narrow edge strip 19 extending horizontally from the inclined to the upper edge 15 of the block and a
wide bearing surface 20 extending therefrom to the upper edge 16 of the rear face
14 and which surface 20 is provided with a centrally located projection 21 with a
vertical axis of symmetry 22, the lower surface is correspondingly sub- divided into
a narrow edge strip 23 extending horizontally from or similarly inclined to the lower
edge 18 of the rear face 14 of the block and a wide bearing surface 24 extending therefrom
to the lower edge 17 of the front face 13 and provided with a centrally located recess
25 of complementary shape to the projection 21 on the upper face, and which recess
25 has a vertical axis of symmetry 26 which is displaced from that 22 of the projection
21 by the width of the narrow edge strip 19/23.
3. A building block according to claim 1 or 2 characterised in that the upper bearing
surface 20 comprises two substantially planar bearing surfaces 20A, 20B disposed at
an angle to each other to constitute a peaked roof shape 21 with a vertical axis of
symmetry 22 and an extension 19 extending from the bearing surface 20B to the front
face 13 of the block, and the lower bearing surface 24 comprises two substantially
planar bearing surfaces 24A, 24B disposed at an angle to each other to form a recess
25 complementary to said peaked roof surface with a vertical axis of symmetry 26 and
an extension 23 extending from the beanng surface 24B to the rear face 14, the axes
of symmetry 22, 26 being displaced laterally by the width of the extension 19/23 and
equally from the central longitudinal axis of the block.
4. A building block according to claim 3 characterised in that the length of the upper
planar surface 20A extending from the rear face is equal to the length of the lower
planar surface 24A extending from the front face and the length of the other upper
planar 4 surface 20B and extension 19 is equal to the length of the other lower planar
surface 24B and extension 23.
5. A free standing vertical wall structure constructed using a plurality of block
characterised in that the wall structure is constructed using a plurality of blocks
as claimed in any one of the preceding claims, laid in an alternating course sequence
in which a course of blocks each laid with its front face 13 exposed is superimposed
on a course of blocks each laid with its rear face 14 exposed or vice verse when viewed
from either side of the wall structure.
6. A retaining wall structure constructed using a plurality of blocks characterised
in that the wall structure is constructed using a plurality of blocks as claimed in
any one of claims 1 to 4 laid in a course sequence in which a course of blocks is
each laid with its front face 13 exposed superimposed on a like course of blocks.
7. A retaining wall structure constructed using a plurality of blocks, characterised
in that the wall structure is constructed using a plurality of blocks as claimed in
any one of claims 1 to 4, laid in a course sequence in which a course of blocks is
each laid with its front face 13 exposed superimposed on an odd number of courses
in which each odd course consists of blocks each with its front face 13 exposed and
each even course consists of blocks each with its rear face 14 exposed.