BACKGROUND OF THE INVENTION Stackable interengaging bricks for building mortarless walls or the like are known in the art.

For example, PCT international application no PCT/CA96/00348 (international publication no WO 96/38636 indicating a publication date of 5 December 1996) discloses wall building blocks which may be stacked and interlocked without being held together by a binding agent such as mortar. The block has a top face which comprises a tongue element and a bottom face which comprises a mortise element. Both elements are configured in such way that when like blocks are stacked, the bottom face of a block engages with the top face of a like block disposed below while the top face of the block engages with the bottom face of an above-disposed block.

As disclosed in the above-mentioned PCT application, the blocks may be obtained by mechanically splitting a parent block comprising a pair of such blocks joined at the front faces thereof, the front faces being defined by a cleavage line running from an upper groove to a lower groove. A difficulty with the above-mentioned parent block is that it is mechanically split by pressing a splitting device comprising a blade or a knife on one of such grooves, thereby requiring considerable pressure. Mechanical splitting of like parent blocks requires bulky machinery which is expensive, necessitates maintenance and requires several

operators to which it may present a danger. Another difficulty is that the type of block thus obtained presents a front face inevitably having a broken stone appearance, which may not be desirable in all circumstances.

Other breakable blocks are also known which require the use of splitting tools such as chisels or machinery such as splitters in order to be split into a plurality of blocks. For example, reference may be made to U. S. Patent no 697,914 issued to Griffin, U. S. Patent no 1,872,522 to Stuckey, U. S. Patent no 4,335,549 to Dean, U. S. Patent no 5,496,129 to Dube, U. S. Patent no 5,598,679 to Orton et al. and U. S. Patent no 5,688,079 to Bolduc et al.

It would be advantageous to have a breakable block which would be configured in such way that the breaking of such block would not necessitate block splitting machinery.

It would in particular be advantageous to have a breakable block which may be easily broken on site such as by hand, without the use of splitting tools or machinery.

It would also be advantageous to have a manually breakable block which would provide block components with a smooth front wall surface.

It would in particular be advantageous to have a manually breakable block which would provide block components with a smooth front wall surface and which could be manufactured using conventional machinery and moulds.

It would also be advantageous to have a manually breakable block which would provide block components and in which a breakable bridging means would keep the smooth front wall surface of each block component protected from rubbing against one another during shipping and handling.

SUMMARY OF THE INVENTION Accordingly, the present invention, in one aspect, provides a manually breakable block comprising a first block component, a second block component and a manually breakable joining means joining the first block component and the second block component. The manually breakable joining means is manually breakable so as to separate the first block component and the second block component by application of a manual levering action on one block component relative to the other block component.

In accordance with the present invention, the manually breakable joining means may for example comprise a manually breakable bridge component.

In accordance with the present invention, each block component may for example comprise a front wall region and a rear wall region, and the manually breakable bridge component may for example connect the rear wall regions.

In accordance with the present invention, each block component may for example comprise a tongue interlock component and a mortise interlock component and the manually breakable bridge component may be disposed medially between the tongue interlock component and the mortise interlock component of each block component.

In accordance with the present invention, the manually breakable bridge component may for example be disposed adjacent the tongue interlock components.

In accordance with the present invention, the manually breakable bridge component may for example be disposed adjacent the mortise interlock component.

In accordance with the present invention, the manually breakable bridge component may for example connect the front wall regions.

In accordance with the present invention, the front wall region may for example comprise a front wall smooth surface part and a front wall rough surface part and the manually breakable bridge component may for example connect the front wall rough surface parts.

In accordance with the present invention, each first and second block component may for example comprise a foot component and a ledge component and the manually breakable bridge component may for example be disposed medially between the ledge component and the foot component of each first and second block component.

In accordance with the present invention, each front wall smooth surface part may for example be divided by the front wall rough surface part.

In accordance with the present invention, the manually breakable bridge component may for example be disposed adjacent the ledge components.

In accordance with the present invention, the manually breakable bridge component may be disposed adjacent the foot components.

In accordance with the present invention, the manually breakable block may for example comprise a pair of scoring notches disposed to define a break line along which the manually breakable bridge component is breakable.

In accordance with the present invention, the manually breakable block may for example comprise a third block component and a second manually breakable bridge component

connecting the second block component and the third block component.

In accordance with the present invention, the manually breakable joining means may for example comprise a manually breakable joint component.

In accordance with the present invention, the manually breakable joint component may for example join the rear wall regions.

In accordance with the present invention, the manually breakable joint component may for example be disposed adjacent the tongue interlock component.

In accordance with the present invention, each first and second block component may for example comprise an upper face and a lower face opposite the upper face, and the manually breakable bridge component may for example connect the lower face of the first block component and the upper face of the second block component.

In accordance with the present invention, the manually breakable joint component may for example join the front wall regions.

In accordance with the present invention, the manually breakable joint component may for example be disposed adjacent the ledge components.

In accordance with the present invention, the pair of scoring notches disposed to define a break line along which the manually breakable joint component is breakable.

It is to be understood herein, that the expression"manually breakable"means breakable by hand, for example such as discussed hereinafter.

It is to be understood herein that the expression"manual levering action"means that the block components may act to display a lever-like function and may even amplify the force applied thereto. The block components may for example be pivoted about a longitudinal axis passing through the manually breakable bridging means which acts as a pivot point. A respective part of each block component may for example be gripped by hand, either directly or indirectly, and force may be applied on the block components, either inwardly, so as to push the respective parts of the block components towards one another, or outwardly, so as to pull them away from one another. The stress thereby created exerts a tension about the manually breakable bridging means which overcomes its strength i. e. cohesiveness at a break line and causes breakage of the manually breakable bridging means and subsequent separation of one block component from the other. The parts of each block component which are gripped may for example be different i. e. one may grip an upper part of the first block component and a lower part of the second bloc component, as long as respective parts are pushed either towards one another or away from one another.

As mentioned above, the manually breakable bridging means may for example comprise a manually breakable bridge component which connects the block components at a distance from one another. The manually breakable bridging means may for example comprise a manually breakable joint component. In this case, the manually breakable joint component may join the block components such that they are flushed with one another i. e. directly abutting or immediately adjacent to one another.

It is to be understood that the manually breakable bridging means is configured to facilitate the manual breakage of the manually breakable bridging means and to provide strength or cohesiveness to hold the block components together during transport and handling, prior to their separation by a user.

The cohesiveness of the manually breakable bridging means may vary depending on the

material forming the manually breakable block. The manually breakable block may be formed of concrete, clay, aggregate or any other suitable material such as a mouldable material adapted to be broken. For example, the manually breakable block may be formed with a concrete mix of 61% sand, 27% aggregate, 8% cement and 2% adjuvant.

The cohesiveness of the manually breakable block is such that parts of same do not fall off during the breaking of the manually breakable bridging means. The manually breakable block may be symmetrical in shape relative to a longitudinal plane vertically crossing the manually breakable bridging means at its midpoint. However, the manually breakable block may also present another configuration such as an asymmetrical shape.

It is to be understood herein that the expression"front wall region"refers to the surface of the block component which is generally exposed when a structure such as a wall or the like is built using a plurality of such block components.

It is to be understood herein that the expression"smooth surface"refers to a surface having an appearance given by a mould. The surface given by the mould may be smooth, i. e. of a uniform appearance as opposed to a broken stone appearance.

The block components obtained with the present invention may have a front wall region comprising a front wall smooth surface part which covers in part or in totality the front wall region of the block component. In some cases as mentioned above, the front wall smooth surface part obtained after breaking the manually breakable block may have a front wall rough surface part. In some cases, the front wall smooth surface part may be divided by the front wall rough surface part.

It is to be understood herein that the expression"scoring notch"refers to an indentation such

as a line or a groove in a surface which by creating a discontinuous surface localises the breakage at a breakpoint and allows for a regular breakage along a break line defined by a pair of such scoring notches.

The present invention will now be described with respect to the drawings which illustrate example embodiments of the present invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a lateral side elevation view of a parent block of the prior art; FIG. 2 is a perspective view of an example manually breakable block in accordance with the present invention; FIG. 3 is a lateral side elevation view of the example block shown in Figure 2; FIG. 3A is a lateral side elevation view of the example block shown in FIG. 2, shown in the process of being broken; FIG. 3B is a lateral side elevation view of the example block shown in FIG. 2, shown in the process of being broken; FIG. 4 is an enlarged view showing the manually breakable bridging means of the example block shown in Figure 3; FIG. 4A is an enlarged view of the manually breakable bridging means shown in Figure 3, showing three different configurations for the example manually breakable bridging means;

FIG. 5 is a lateral side elevation view of another example manually breakable block in accordance with the present invention; FIG. 6 is a lateral side elevation view of yet another example manually breakable block in accordance with the present invention; FIG. 7 is a lateral side elevation view of the example block of Figure 6 shown in the process of being broken; FIG. 8 is a lateral side elevation view of a pair of block components obtained from the breaking of the example block shown in Figure 2; FIG. 9 is a perspective view of yet another example manually breakable block in accordance with the present invention; FIG. 10 is a lateral side elevation view of the example block shown in Figure 9; FIG. 11 is an enlarged view showing the manually breakable bridging means of the example block shown in Figure 10; FIG. 12 is a lateral side elevation view of yet another example manually breakable block in accordance with the present invention; FIG. 13 is a lateral side elevation view of yet another example manually breakable block in accordance with the present invention;

FIG. 14 is a lateral side elevation view of the example block shown in Figure 9, shown in the process of being broken; FIG. 15 is a lateral side elevation view of the example block shown in Figure 9, showing an alternate method of breaking; FIG. 16 is a lateral side elevation view of a block component resulting from the breaking of the example block shown in Figure 9; FIG. 17 is a lateral side elevation view of a pair of block components obtained from the breaking of the example block shown in Figure 9; FIG. 18 is a perspective view of a portion of a wall comprising stacked block components such as the block components shown in Figure 17; FIG. 19 is a lateral side elevation view of yet another example block in accordance with the present invention; FIG. 20 is a top view of a mould used to obtain the example block shown in Figure 9; FIG. 21 is a lateral side elevation view of yet another example block in accordance with the present invention; FIG. 22 is a lateral side elevation view of the block components obtained from the breaking of the example block illustrated in Figure 21;

FIG. 23 is a lateral side elevation view of yet another example block in accordance with the present invention; FIG. 24 is a lateral side elevation view of the block components obtained from the breaking of the example block illustrated in Figure 23; and FIG. 25 is a lateral side elevation view of yet another example block in accordance with the present invention.

Referring to the drawings and more particularly to FIG. 1, there is shown a parent block 10 as described in the above-mentioned PCT international application. The parent block 10 comprises a pair of blocks 11,12 joined at the front faces thereof, the front faces being defined by a cleavage line running from an upper groove 13 to a lower groove 14. The blocks 11,12 each have a respective top face 15 comprising a tongue interlock element 16 and a ledge element 17, and a respective bottom face 18 comprising a mortise interlock element 19 and a foot element 20. The tongue interlock element 16 and the mortise interlock element 19 may be configured in such way that when blocks 11 and 12 are stacked one on top of the other, the bottom face 18 of block 11 may engage with the top face 15 of block 12 disposed below while the top face 15 of block 11 may engage with the bottom face 18 of an above-disposed block.

Referring now to FIG. 2 and FIG. 3, there is shown an example manually breakable block in accordance with the present invention. The manually breakable block 21 comprises a first block component 22, a second block component 23 and a manually breakable bridging means 24 which joins the first block component 22 and the second block component 23. In the example shown herein, the manually breakable bridging means 24 is a manually breakable bridge component 24 connecting the first and second block components. Since the

first and second block components 22,23 are essentially similar once separated one from another, their components will hereinafter be designated by the same reference numerals.

Each first and second block component 22,23 comprises a first lateral side face 25 and a second lateral side face 26 opposite the first lateral side face 25. Each first and second block component 22,23 comprises an upper face 27 longitudinally extending from the first lateral side face 25 to the second lateral side face 26. The upper face 27 defines a tongue interlock component 28, a ledge component 29 and a first intermediate face 30 which connects the tongue interlock component 28 and the ledge component 29. A lower face 31 opposite the upper face 27 extends longitudinally from the first lateral side face 25 to the second lateral side face 26. The lower face 31 defines a mortise interlock component 32, a foot component 33 and a second intermediate face 34 which connects the mortise interlock component 32 and the foot component 33.

A front wall region 35 longitudinally extends from the first lateral side face 25 to the second lateral side face 26. The front wall region 35 connects the ledge component 29 of the upper face 27 and the foot component 33 of the lower face 31. The front wall region 35 comprises a front wall smooth surface part 36. In the example manually breakable block 21 shown herein, the front wall smooth surface part 36 essentially covers in totality the front wall region 35, i. e. the front wall region 35 has an overall smooth surface.

Each first and second block component 22,23 also comprises a rear wall region 37. The rear wall region 37 extends longitudinally from the first lateral side face 25 to the second lateral side face 26. The rear wall region 37 connects the mortise interlock component 32 of the lower face 31 and the tongue interlock component 28 of the upper face 27. The example manually breakable block 21 shown herein is configured such that the rear wall regions 37 face one another. Each rear wall region 37 comprises a rear wall smooth surface part 38

which in the example shown herein is divided in two parts by the manually breakable bridge component 24, i. e. both above and below the manually breakable bridge component 24.

The manually breakable bridge component 24 extends longitudinally from the first lateral side face 25 to the second lateral side face 26. However, the manually breakable bridge component 24 may for example be shorter or discontinuous i. e. in two or more spaced apart bridge component sections. As may be seen, the manually breakable bridge component 24 connects the rear wall regions 37, i. e. a part of each rear wall region 37 is kept hidden by the manually breakable bridge component 24. The hidden part only becomes visible once the manually breakable bridge component 24 is broken, as will be described further below.

In the example shown herein, the manually breakable bridge component 24 is disposed medially between the mortise interlock component 32 and the tongue interlock component 28 of each block component 22,23. However, the manually breakable bridge component 24 may be disposed anywhere between the mortise interlock component 32 and the tongue interlock component 28 of each block component 22,23.

Referring now to FIG. 4, this figure shows an enlarged view of the manually breakable bridge component 24 of the example manually breakable block 21 illustrated in FIG. 3. As may be seen, the manually breakable bridge component 24 comprises a first scoring notch 39a which is disposed between the manually breakable bridge component 24 and the rear wall smooth surface part 38 adjacent the tongue interlock component 28 of the first block component 22. A second scoring notch 39b is disposed opposite the first scoring notch 39a between the manually breakable bridge component 24 and the rear wall smooth surface part 38 adjacent the mortise interlock component 32 of the first block component 22. The first and the second scoring notches 39a, 39b form a first pair of opposed scoring notches which defines a first break line, as illustrated with the dotted line identified with the letter A. A

third scoring notch 39c is disposed between the manually breakable bridge component 24 and the rear wall smooth surface part 38 adjacent the tongue interlock component 28 of the second block component 23. A fourth scoring notch 39d is disposed opposite the third scoring notch 39c between the manually breakable bridge component 24 and the rear wall smooth surface part 38 adjacent the mortise interlock component 32 of the second block component 23. The third and fourth scoring notches 39c, 39d form a second pair of opposed scoring notches which defines a second break line as shown with the dotted line identified with the letter B. In the example shown herein, the scoring notches 39a, 39b, 39c, 39d extend longitudinally from the first lateral side face 25 to the second lateral side face 26, i. e. along the manually breakable bridge component 24. Although the example shown herein is provided with scoring notches 39a, 39b, 39c, 39d, the manually breakable block 21 may alternatively not present such scoring notches.

Turning now to FIG. 4A, this figure shows an enlarged side view of the manually breakable bridge component 24 shown in FIG. 4. As mentioned above, the manually breakable bridge component 24 is configured to facilitate its manual breakage while at the same time providing sufficient strength, or cohesiveness, to hold the first and second block components 22,23 together during transport and handling of the manually breakable block 21.

As mentioned above, the cohesiveness of the manually breakable bridge component 24 may vary depending on the material forming the manually breakable block. Accordingly, the manually breakable bridging means 24 will have dimensions which will vary depending on the material used and the composition of the material. For example, in the case where the manually breakable block 21 is formed with a concrete mix of 61% sand, 27% aggregate, 8% cement and 2% adjuvant, the dimensions of the manually breakable bridge component 24 may be as follows. These dimensions are given with respect to a manually breakable bridge component 24 extending from one lateral side face to the other as shown herein. The

dimensions of the manually breakable bridge component may vary if the manually breakable bridge component 24 is shorter or discontinuous, as mentioned above. It is important to note that these dimensions are given with respect to an example block 21 having a height of 150 mm indicated by the arrow P in FIG. 3, a block component thickness of 65 mm indicated by the arrow Q and a length of 230 mm which is measured between the first and second lateral side faces 25,26. The dimensions are given here by way of example only.

Returning now to FIG. 4A, the manually breakable bridge component 24 has a length which is identified with the arrow L and which may preferably vary up to about 55 mm. The length L may preferably be of 8 mm. The manually breakable bridge component 24 has a thickness which is measured at a break line between the upper surface and the lower surface. In the example shown herein, the manually breakable block 21 comprise two such break lines as indicated by the arrows identified with the letter TA and TB. The thickness at one break line may vary from 4 mm to 25 mm and may preferably be of 6 mm. The thickness at the first break line TA and the thickness at the second break line TB may be similar as shown herein. However, the thickness at the first break line TA and the thickness at the second break line TB may differ as long as the manually breakable bridge component 24 is manually breakable at one break line; the manually breakable bridge component 24 may be broken at the remaining break line with a hand tool such as a hammer.

The thickness of the manually breakable bridge component 24 between the two break lines as indicated by the arrow identified with the letter Tc is greater than the thickness of the manually breakable bridge component 24 at the break line in the case where there are more than one break line or at break line which is thicker in the case where there are two break lines which differ in thickness. The thickness Tc may preferably be 1.4 times greater than TA or TB. In the example shown herein, the thickness Tc may preferably be of 12 mm

The manually breakable bridge component 24 may take any configuration which allows the manual breakage of same. For example, the manually breakable bridge component 24 may take a configuration such as the configuration illustrated with the line D. The manually breakable bridge component 24 may also take a configuration such as the ones illustrated with the dashed line E or the dotted line F.

Returning now to FIG. 3, the example manually breakable block shown herein may be broken as follows. The first and second block components 22,23 may be gripped for example around their respective foot component 33. The block components 22,23 may be gripped directly or indirectly. A manual levering action may be applied by pressing onto the block components 22,23 to direct the foots components 33 towards one another such as indicated by the arrows 13A. In this case, the block components 22,34 may act to display a lever-like function and may even amplify the force applied thereto. The manual levering action exerts a tension for example about the scoring notch 39a which overcomes the cohesive force of the manually breakable bridging means 24 at the first break line. The block components are pivoted about the longitudinal axis of the manually breakable bridging means which acts as a pivot point. Breakage of the manually breakable bridging means 24 along the break line from the first scoring notch 39a to the second scoring notch 39b occurs with the subsequent separation of the first block component 22 from the second block component 23, as shown in FIG. 3A.

Alternatively, a force may be applied on the block components outwardly i. e. in the direction of the arrows 13B, so as to pull them away from one another. The stress thereby created would exert a tension about the second scoring notch 39b and cause breakage of the manually breakable bridge component from the second scoring notch 39b to along the first break line to the first scoring notch 39a and subsequent separation of the block components from one another. The gripped part of each block component may be different i. e. one may

grip an upper part of a first block component and a lower part of another block component, as long as respective parts are either pushed towards one another or pulled away from one another.

Turning now to FIG. 3A, the breaking of the manually breakable bridge component 24 exposes a rough surface part 40 on the manually breakable bridge component 24 and a rear wall rough surface part 41 on the first block component 22 where the manually breakable bridge component 24 was connected. In the case where the manually breakable bridge component or a portion thereof remains attached to one of the block components, it may be removed by knocking it off such as with a hammer. For example, the user may knock the manually breakable bridge component 24 off by hitting same such as in the direction of the arrow 14A, which would cause breakage of the manually breakable bridge component 24 along the second break line and the removal of the manually breakable bridge component 24 or the attached part thereof from the second block component 23, as shown in FIG. 3B. Other suitable means which would separate the manually breakable bridging means 24 or a part thereof which remained attached to one of the block components may also be used.

As a result of the breaking of the manually breakable block 21, block components may be obtained of the type disclosed in the above-mentioned PCT international application, the entire content of which is incorporated herein for reference.

Turning now to FIG. 5, this figure shows another example manually breakable block 21 in accordance with the present invention which configuration differs from that of the example block illustrated in FIG. 2 in that the manually breakable bridge component 24b is disposed adjacent the tongue interlock component 28 of each block component 22,23. In the example shown herein, the rear wall smooth surface part 38 of each rear wall region 37 is not divided by the manually breakable bridge component 24b. The first and third scoring notches

39a', 39c' are disposed between the manually breakable bridge component 24b and the tongue interlock component 28 of their respective block component 22,23 while the second and fourth scoring notches 39b', 39d' are disposed between the manually breakable bridge component 24b and the rear wall rough surface part 36 of the respective block components 22,23.

FIG. 6 shows yet another example manually breakable block 21 in accordance with the present invention which configuration differs from those of the example blocks illustrated previously in that the manually breakable bridge component 24c is disposed adjacent the mortise interlock component 32 of each block component 22,23. As in the example block illustrated in FIG. 5, the rear wall surface part 38 of each rear wall region 37 is not divided by the manually breakable bridge component 24c. The first and third scoring notches 39a", 39c" are disposed between the manually breakable bridge component 24c and the rear wall smooth surface part 38 of their respective block component 22,23 while the second and fourth scoring notches 39b", 39d" are disposed between the manually breakable bridge component 24c and the mortise interlock component 32 of their respective block component 22,23.

The example manually breakable block 21 shown in FIG. 6 may be broken as follows. The first and second block components 22,23 is gripped for example around their respective foot component 33 and a manual levering action is applied by pressing onto the block components 22,23 so as to direct the foot components 33 towards one another as shown by the arrows 16A. The manual levering action exerts a tension for example about the first scoring notch 39a"which overcomes the cohesive force at the first break line and causes breakage of the manually breakable bridge component 24c along the first break line from the first scoring notch 39a"to the second scoring notch 39b"and subsequent separation of the first block component 22 from the second block component 23, as shown in FIG. 7. A

similar result may be obtained by gripping each block component 22,23 around their respective tongue interlock component 28 and by pulling onto the block components 22,23 so as to direct the tongue interlock components 28 away from one another as shown by the arrows 16B in FIG. 6.

Turning now to FIG. 7, the breaking of the manually breakable bridge component 24c exposes a rough surface part 40'on the manually breakable bridge component 24c and a rear wall rough surface part 41'on the block component 22 where the manually breakable bridge component 24c was connected.

The manually breakable bridge component 24c may then be removed by knocking it off such as described above with respect to FIG. 3A.

Referring now to FIG. 8, this figure shows the block components 22,23 obtained from the breaking of the example manually breakable block 21 shown in FIG. 3. As mentioned above, the block components 22,23 are essentially the same after separation. The orientation of the first block component 22 has been laterally inverted such that its second lateral side face 26 is now facing the plane of the sheet. As may be seen, the first block component 22 is disposed above the second block component 23 in a stackable interlocking relationship. The front wall smooth surface 36 covers in totality the front wall region 35 of each block component 22,23 while their respective rear wall region 37 comprises a smooth surface part 38 divided by a rough surface part 41.

FIG. 9 and FIG. 10 show yet another example block in accordance with the present invention. In this case, the manually breakable bridge component 24d connects the respective front wall regions 35, i. e. the rear wall regions 37 are not connected with the manually breakable bridge component 24d. The front wall regions 35 face one another. The

manually breakable bridge component 24d is disposed adjacent the ledge component 29 of each block component 22,23. Each front wall region 35 is composed of the smooth surface part 36 which is disposed below the manually breakable bridge component 24d and of a rough surface part which is hidden by the manually breakable bridge component 24d.

However, the front wall regions 35 completely appear once the block components 22,23 are separated, as will be better described further below.

FIG. 11 shows an enlarged view of the manually breakable bridge component 24d of the example manually breakable block 21 shown in FIG. 10. The manually breakable bridge component 24d includes a pair of scoring notches 43,44 opposed one another and disposed in an upper and lower orientation. The scoring notches 43,44 extend longitudinally from the first lateral side face 25 to the second lateral side face 26 as seen in FIG. 9. The scoring notches 43,44 and define a break line going from the first scoring notch 43 to the second scoring notch 44 as indicated by the dotted line and along which the manually breakable bridge component 24d is breakable.

FIG. 12 shows yet another example manually breakable block 21 in accordance with the present invention which configuration differs from that of the example block shown in FIG.

9 in that the manually breakable bridge component 24d is disposed adjacent the foot component 33 of each block component 22,23. The respective front wall smooth surface parts 36 are now disposed above the manually breakable bridge component 24d.

FIG. 13 shows yet another example of manually breakable block 21 in accordance with the present invention which differs from the example blocks shown in FIG. 9 and 12 in that the manually breakable bridge component 24d is disposed medially i. e. at equal distance between the ledge component 29 and the foot component 33 of each block component 22,23. However, the manually breakable bridge component 24d may be disposed anywhere between

the ledge component 29 and the foot component 33. The front wall smooth surface part 36 of each block component 22,23 is divided by the manually breakable bridge component 24d, i. e. the front wall smooth surface part 36 is divided in two parts which are disposed both above and below the manually breakable bridge component 24d.

Turning now to FIG. 14a, as described above, the manually breakable block 21 may be broken by gripping each block component such as around its respective tongue interlock component 28 and by applying a manual levering action in the direction of the arrows 14.

The breaking of the manually breakable bridge component 24d reveals a front wall rough surface part 42 for each block component 22,23. A similar result may be obtained by gripping the block components 22,23 around their respective foot component 33 and by applying a levering action in the direction of the arrows 14B.

FIG. 15 shows another way of breaking the manually breakable block 21 into first and second block components 22,23. The block components 22,23 are gripped for example around their respective tongue interlock component 28 and a manual levering action is applied by pulling the tongue interlock components 28 away from one another in the direction of the arrows 15A. A similar result is obtained if the block components 22,23 are gripped such as around their respective foot component 33 and a manual levering action is applied by pushing the respective foot components 33 against one another as shown with arrows 15B.

Referring now to FIG. 16, after separation of the block components 22,23 the front wall region 35 comprises the front wall smooth surface part 36 and the front wall rough surface part 42. The front wall rough surface part 42 projects from the front wall region 35 and extends longitudinally from the first lateral side face 25 to the second lateral side face 26. Since the front wall rough surface part 42 results from the breakage of the manually

breakable bridge component 24d, it presents a broken stone appearance.

FIG. 17 illustrates the first block component 22 and the second block component 23 obtained from the breaking of the manually breakable block 21 shown in FIG. 10 and disposed in a stacked interlocking relationship with each other. The lateral orientation of the second block component 23 has been inverted with a 1800 turn such that the second lateral side face 26 is now facing the plane of the sheet.

FIG. 18 illustrates how a plurality of like block components 22 and 23 obtained from the breaking of the manually breakable block 21 illustrated in FIG. 10 may be stacked so as to build a wall or the like without using a binding agent such as mortar. As may be seen according to the example shown, the front wall rough surface part 42 presents a broken stone appearance, while the front wall smooth surface part 36 presents a smooth appearance.

Turning now to FIG. 19, there is shown an example manually breakable block 21'in accordance with the present invention which comprises more than two block components. In the example shown in that figure, the manually breakable block 21'comprises a first block component 49 connected to a second block component 50 by a first manually breakable bridging means 51 in a configuration similar to that of the embodiment of the manually breakable block illustrated in FIG. 10. i. e. the manually breakable bridge component 51 connects the front wall regions 35 of the first and second block components 49,50 adjacent the ledge components thereof. However, the configuration of the manually breakable block 21'differs in that a third block component 52 is connected to the second block component 50 by a second manually breakable bridge component 53 i. e. the second manually breakable bridge component 53 connects the rear wall region 37 of the second block component 50 and the rear wall region 37 of the third block component 50 adjacent their mortise interlock component 32. A fourth block component 54 is connected to the third block component 52

by a third manually breakable bridge component 55. The manually breakable bridge component 55 connects the front wall region 35 of the third block component 52 and the front wall region 35 of fourth block component 54 adjacent their ledge components 29.

Turning now to FIG. 20, an advantage of the example manually breakable blocks 21 shown in FIG. 10,12 and 13 is that they may be manufactured using conventional manufacturing machinery and moulds such as the machinery and moulds used to produce the parent block described in the above-mentioned PCT international application, i. e. a model V3-12F Vibrapac splitting machine manufactured by Besser. As may be seen in that figure, a modification to the mould of the prior art such as the insertion of a projection 56 opposite the scoring notch 43 inside the mould is needed to provide for the front wall smooth surface parts 36 of the front wall regions 37 of the example manually breakable block 21 shown in FIG. 10.

Turning now to FIG. 21, there is illustrated yet another example manually breakable block 21 in accordance with the present invention. The manually breakable bridging means is a manually breakable joint component 24e. As mentioned above, the manually breakable joint component joins the rear wall regions of the first and second block components 22,23 such that they are flushed with one another i. e. directly abutting or immediately adjacent to one another. In the example shown herein, the manually breakable joint component 24e joins the rear wall region 37 of the block components 22,23 adjacent their respective tongue interlock component 28. Opposed scoring notches 45,46 define a break line shown with a dotted line along which the manually breakable joint component 24e may be broken.

FIG. 22 shows the block components 22,23 obtained after breaking the example block 21 illustrated in FIG. 21 and disposed in a stacked interlocking relationship.

FIG. 23 shows yet another example manually breakable block 21"in accordance with the present invention. The configuration of the example block 21"shown herein differs from that of the example blocks 21 described above in that the manually breakable joint component 24f joins the lower surface 31 of the first block component 22 and the upper surface 27 of the second block component 22. More particularly, the manually breakable joint component 24f joins the second intermediate face 34 of the lower face 31 of the first block component 22 and the first intermediate face 30 of the upper face 27 of the second block component 23.

The manually breakable joint component 24f comprises a first scoring notch 47 and a second scoring notch 48 disposed opposite the first scoring notch 47 to define the break line along which the manually breakable joint component 24f may be broken.

FIG. 24 shows the block components 22,23 obtained after breaking the example block 21" illustrated in FIG. 23 and disposed in a stacked interlocking relationship.

FIG. 25 shows yet another example manually breakable block 21"'in accordance with the present invention. The manually breakable joint component 24g joins the front wall regions 35 of the block components 22,23. The orientation of the first block component 22 is longitudinally inverted compared to the example blocks 21 previously described. In other words, the upper face 27 of the first block component 22 is adjacent the lower face 31 of the second block component 23 and vice-versa. The first scoring notch 47 is disposed adjacent the front wall region 35 of the first block component and the upper face 27 of the second block component 23. The second scoring notch 48 is disposed opposite the first scoring notch 47 adjacent the upper face 27 of the first block component 22 and the front wall region 35 of the second block component 23.

Another advantage of the blocks such as the example manually breakable blocks 21 shown in FIG. 10,12,13 and 19, i. e. with the manually breakable bridging means 24 connecting the

front wall region 35 of each block component 22,23 is that the front wall smooth surface part 36 of each front wall region 35 is protected from rubbing against one another during handling and shipping and is kept intact until usage by a user by the manually breakable bridging means 24 which connects the front wall regions 35 at a distance from one another.

Although particular examples of the breakable block in accordance with the present invention have been illustrated and described, it is to be understood that the present disclosure is made by way of example and that various other embodiments are possible without departing from the subject matter coming within the scope of the following claims, which subject matter is regarded as the invention.