The present invention is related to the building industry. More particularly, it relates to a dry stack building block, a dry stack system, a prefabricated wall panel, a building, a method for building a dry stack structure, a method for manufacturing a dry stack building block and a mould system for carrying out a method for manufacturing a dry stack building block.

In conventional housing, walls and similar structures are often constructed by means of masonry with mortar. Typically, a foundation layer of concrete is formed in the ground and a layer of mortar is applied on top. Subsequently, a row of bricks is pressed into the mortar. Next, mortar is laid on top of the bricks and end faces of bricks to be stacked on the brick row are buttered with mortar. Finally, the buttered bricks are laid on top of the row, after which the process is repeated until the stacked structure has the desired dimensions.

An important advantage of this technique is that the mortar allows size differences between the bricks and irregularities of the contact surface between two layers of bricks. By applying less or more mortar between two (rows) bricks, mutual size differences and irregularities can be eliminated. Consequently, the manufacturing of conventional masonry bricks does not need to be precise, as a result of which the bricks can be cheap. A disadvantage of masonry with mortar is, however, that the application of the mortar is labour intensive and the drying time of the mortar is rather time consuming. As an alternative method, dry stacking was introduced, wherein dry stack bricks are stacked or clicked onto each other without applying any mortar between them. Dry stacking allows building a wall or similar structure in less time even by non-specialists. Related advantages include less material costs, less labour and no need to clean the mortar after wear.

However, as no mortar is applied in between dry stack building blocks, both their size, in particular their height, and the roughness of their contact surfaces with other building blocks are critical in realizing a close fit between building blocks and obtaining a stacked structure which is both stable and strong. Therefore, current building blocks are grinded and polished after being produced to obtain the right size and level out any contact-surface irregularities. This post-processing is however both laborious and time consuming, which is a problem in a commodity industry like the building industry. It is therefore an object of the invention to provide an improved dry stack building block, which does not require laborious and time-consuming post-processing. The invention provides hereto a dry stack building block, comprising a bottom surface and a top surface, wherein at least one of the bottom and top surfaces comprises a protruding portion near opposing edges thereof, forming ridges therealong, serving as supporting surfaces for at least one other dry building block to be stacked thereagainst. In this way, the contact surface between two dry stack building blocks is drastically reduced, as a result of which the possible influence of surface irregularities on the stability of a stacked dry stack building block is significantly reduced. For stability reasons, it is preferred that the protruding portion is arranged symmetrically about an axis extending in the stacking direction through the centre of mass of the building block. As the ridges are arranged along opposing edges of the bottom and/or top surface, a side face of each ridge may be coplanar with a front face and/or a back face of the dry stack building block, such that a front face and/or a back face of a stacked structure of such dry stack building blocks do not show any gaps between the building blocks, resulting in a seamless wall structure. It is noted, however, that said side faces of the ridges do not necessarily have to be coplanar with the front face and/or back face of the dry stack building block, but can also be arranged - for instance for esthetical reasons - inwardly relative to the front and back face of the building block, such that small gaps are formed between the building blocks, so that it gives the impression that dry stack building blocks in a stacked configuration are slightly apart from each other. Preferably, the dry stack building block has the shape of a cuboid with a top and a bottom side, a front and a back face, and a pair of end faces, each of which has a substantially rectangular shape. Further, the top surface preferably comprises the protruding ridges, whereas the bottom is substantially flat. The protruding portion preferably has a height of about 1-15 % of the height of the dry stack building block.

According to a preferred embodiment, the dry stack building block further comprises a through- hole extending between the bottom and top surface. After stacking, this through-hole can be filled with mortar, concrete or the like, through which the building block can be solidly connected with superjacent and/or subjacent building blocks with through-holes, which are aligned with the through-hole of the subjacent and/or superjacent building block . As a result, a dry stack construction with columns of mortar, concrete or the like therein is obtained, forming a very solid, strong and stable structure.

It is noted that although the through-hole and the configuration thereof is described in combination with the ridge-like protruding portion on the bottom or top surface, the invention also envisages dry stack building blocks with a through-hole as described above, but without said protruding portion. According to a further preferred embodiment, one of the bottom and top surfaces comprises a second protruding portion near one end of the through-hole, and the through-hole widens towards the other one of the bottom and top surfaces, thereby forming a recessed portion therein, wherein an outer diameter of the second protruding portion is smaller than or equal to an inner diameter of the recessed portion. The second protruding portion preferably has the shape of a closed-loop ridge running around the end opening of the through-hole. A particular advantage of the recessed portion is that any possible negative influence of burrs at the top/bottom surface of a subjacent/superjacent building block on the stacking stability of a superjacent/subjacent building block is minimized. The protruding portion on the other side surface is formed such that it fits in the recessed portion without being in contact with the outer surface of the superjacent/subjacent building block. This may further streamline the mortar, concrete or the like to be introduced in the through-holes.

According to a further preferred embodiment, a radially outwardly facing surface of the second protruding portion and a radially inwardly facing surface of the recessed portion are slanted, such that the second protruding portion and the recessed portion taper in the same direction. A particular advantage of correspondingly tapered protruding and recessed portions is that it further facilitates the collapse of the poured-in mortar, concrete or the like in the through-holes. In a more preferred embodiment, the through-hole has a substantially cylindrical shape, and the radially outwardly facing surface of the second protruding portion and the radially inwardly facing surface of the recessed portion form part of a cone. A cylindrical through-hole and a conically tapered second protruded portion and recessed portion enable a good filling of the through-hole and of any present cavities between stacked dry stack building blocks with mortar or concrete or the like. According to a further preferred embodiment, a tapering angle of the second protruding portion is larger than a tapering angle of the recessed portion. Specifically, conically tapered recessed and protruding portions, wherein a tapering angle of the protruding portion is larger than a tapering angle of the recessed portion, allow the poured-in mortar, concrete or the like to easily sink in the through-holes while at the same time achieving a high mortar/concrete -filling degree in and between the individual building blocks. According to a further preferred embodiment, the dry stack building block further comprises a channel extending between surfaces of the dry stack building block for receiving a reinforcing rod. A particular advantage of this channel is that it allows a row or column of building blocks to be interconnected by a reinforcing rod that is embedded in the channel. Preferably, the channel has the form of a groove in at least one of the bottom and top surfaces, which groove extends in a longitudinal direction between end faces of the dry stack building block and across an opening of the through-hole. The interconnection on the one hand, and the orientation of the groove and the rod perpendicular to the through-holes on the other, enables a very stiff construction of dry stack building blocks. In particular, a groove which extends across an opening of the through-hole is beneficial, since the reinforcing rod becomes surrounded and therefore gets fixed by the mortar, concrete or the like poured in the through-holes.

According to a further preferred embodiment, the dry stack building block further comprises a conduit through-hole, preferably extending between the bottom and top surfaces, for installing conduits and/or pipework therethrough. A particular advantage of such a through-hole is that pipework can already be integrated with the wall during construction, so that no slots have to be milled into the constructed wall after construction. This saves valuable time at the building site. The conduit through-hole differs from the aforementioned channel for a reinforcing rod in that the conduit through-hole has a diameter which is typically 2-3 times larger than that of said channel, and in that the channel is preferably to be filled with mortar or concrete or the like while the conduit through-hole is preferably left unfilled with such a substance.

According to a further preferred embodiment, an inner wall of the conduit through-hole tapers conically near one of the bottom and top surfaces, such that a bore of the conduit through-hole widens towards said surface. Like the conically tapered through-holes for receiving mortar, concrete or the like, the conical tapering and widening toward the surface minimizes any possible negative influence of burrs at the top/bottom surface of a subjacent/superjacent building block on the stacking stability of a superjacent/subjacent building block and facilitates the insertion of electrical cables, water and drainage pipework and the like in the through-holes, while at the same time achieving a high fill factor. According to a further preferred embodiment, a set of through-holes, comprising the through-hole and/or the conduit through-hole, is provided symmetrically about a centre plane of the building block at a predetermined pitch, such that the through-holes of the set align with through-holes of a superjacent and/or subjacent building block to be stacked with a horizontal offset thereagainst, wherein the offset corresponds to a multitude of the pitch. This specific positioning of the through- holes enables constructing a dry stack structure in various types of load-bearing bonds, such as stretcher bond, header bond, Flemish bond or English bond, without the through-holes being closed off by superjacent building blocks. In other words, a structure can be built in a specific bond with straight columns of mortar or concrete inside. The bond further increases the strength and stability of a structure built with the dry stack building block of the present invention. According to a further preferred embodiment, the set of through-holes comprises a through-hole centred at the centre plane and through-holes centred at end faces of the building block, such that lengthwise cut-in half through-holes are formed at the end faces. In this way, a certain bond can be formed by pairing and placing two halved through-holes of two building blocks above a through- hole of a subjacent building block. The more through-holes are provided in the building block, the more different bond structures can be realized.

According to a further preferred embodiment, the building block is cut in half along a centre plane. A half-length dry stack building block allows forming straight edges of a stretcher-bond structure. A half -width or half -height dry stack building block is beneficial for walls on which a floor is placed, as it provides thermal isolation between the floor and the outer side of the wall of a building and therewith prevents the formation of a thermal bridge.

According to a further preferred embodiment, a cross-section of the building block has a U-shape, wherein a space between legs of the U-shape forms a trench for receiving concrete and/or a structural member therein, wherein the trench extends parallel or perpendicular to the through-hole. A particular advantage of such a U-shaped dry stack building block, also called a lintel block, is that a reinforcing beam, rod, bar or the like can be placed into the trench. Through filling the through-holes, which debouch into the trench, the trench can be filled with mortar, concrete or the like, such that the mortar, concrete or the like is in contact with mortar or concrete in the through- hole, as a result of which an arch abutment can be formed, which further increases the strength and stiffness of the stacked wall structures.

Preferably, the dry stack building block is made of a mix of cement, expanded clay aggregate or pumice, sand, water and a liquid that impregnates the clay aggregate, and its density is preferably less than 1000 kg/m ³ and its compressive strength is preferably equal to or more than 10 N/mm ² .

The invention further relates to a dry stack system, comprising a plurality of dry stack building blocks, preferably dry stack building blocks according to the invention, each comprising a bottom surface and a top surface and a through-hole extending between the bottom and top surfaces, wherein at least one of the bottom and top surfaces comprises a protruding portion near opposing edges thereof, forming ridges therealong, serving as supporting surfaces for other dry building blocks to be stacked thereagainst, wherein the dry stack building blocks are each oriented in the same direction and stacked against each other, such that the protruding portion is in direct contact with an superjacent and/or subjacent building block and the through-hole is aligned with a through- hole of the superjacent and/or subjacent building block, and wherein the through-holes are filled with mortar, concrete or the like. As a beneficial consequence of the protruding portion, the contact surface between two dry stack building blocks is drastically reduced, as a result of which the possible influence of surface irregularities on the stability of a stacked dry stack building block is significantly reduced. As the protruding portion comprises ridges along opposing edges of the bottom and/or top surface, the dry stack building blocks can be stacked such that a front face and a back face of the stacked structure do not show any gaps between the building blocks, resulting in a seamless wall structure. The aligned through-holes can be filled with mortar, concrete or the like, through which the building blocks can be solidly connected with superjacent and/or subjacent building blocks. As a result, a dry stack construction with columns of mortar, concrete or the like therein is obtained, forming a very solid, strong and stable structure.

According to a preferred embodiment, the dry stack system further comprises a reinforcing rod for reinforcing the dry stack system, being embedded in mutually aligned grooves of adjacent building blocks, each groove being provided in at least one of bottom and top surfaces of each of the plurality of building blocks and extending in a longitudinal direction between end faces of the building block. The reinforcing rod allows a row of building blocks to be interconnected. The interconnection on the one hand and the orientation of the groove and the rod perpendicular to the through-holes on the other enables a very stiff construction of dry stack building blocks. In particular, a groove which extends across an opening of the through-hole is beneficial, since the reinforcing rod becomes surrounded and therefore gets fixed by the mortar, concrete or the like poured in the through-holes.

According to a further preferred embodiment, a conduit through-hole for installing conduits and/or pipework therethrough is provided in each of the plurality of dry stack building blocks, the conduit through-hole extending between the bottom and top surfaces and being aligned with a conduit through-hole of a superjacent and/or subjacent building block. A particular advantage of these through-holes is that pipework can already be integrated with the wall during construction, so that no slots have to be milled into the constructed wall after construction. This saves valuable time at building site.

According to a further preferred embodiment, the dry stack system further comprises a structural element arranged in mutually aligned trenches of superjacent, subjacent and/or adjacent building blocks, each trench being formed by a space between legs of a U-shape of a cross-section of some of the plurality of building blocks. The structural element can be a reinforcing beam, rod, bar or the like, which is dimensioned such that it fits in the trenches of superjacent, subjacent and/or adjacent building blocks. The trench can be filled with mortar, concrete or the like through filling the through-holes that debouch into the trench, such that the mortar, concrete or the like is in contact with mortar or concrete in the through-hole, as a result of which an arch abutment can be formed, which further increases the strength and stiffness of the stacked wall structures. It is noted that the invention is also related to a kit of parts, needed to produce a dry stack system, preferably a dry stack system according to the invention, comprising at least two dry stack building blocks, preferably dry stack building blocks according to the invention, and a pourable filler material such freshly mixed or precast mortar, concrete or the like, and optionally a reinforcing rod to be embedded in grooves of the at least two dry stack building blocks, and/or pipework and/or conduits/cables to be installed in conduit through-holes of the at least two dry stack building blocks.

The invention further relates to a prefabricated wall panel for constructing a building, comprising a dry stack building block and/or a dry stack system, preferably a block and/or a system according to the invention. A particular advantage of such a prefabricated wall panel is that it further increases the efficiency with which buildings are built at the building site. Not only the assembly of the prefabricated dry stack wall panel takes less time than prefabricating a conventional masonry wall panel, also the construction time at the building site is drastically reduced. The invention further relates to a building comprising a dry stack building block and/or a dry stack system and/or a prefabricated wall panel, preferably a block and/or a system and/or a wall panel according to the invention. A particular advantage of such a prefabricated building is that it increases the efficiency with which buildings are built. The invention further relates to a method for building a dry stack system, a prefabricated wall panel or a building, preferably a system, wall panel or building according to the invention, using a first and a second dry stack building block, preferably a first and a second block according to the invention, comprising aligning a through-hole of the first building block is aligned with a through- hole of the second building block, stacking the first building block against the second building block, such that a protruding portion near opposing edges of at least one of a bottom and a top surface of at least one of the first and second building blocks is in direct contact with the superjacent or subjacent other one of the first and second building blocks, and filling the through- holes with concrete. As a beneficial consequence of the protruding portion, the contact surface between two dry stack building blocks is drastically reduced, as a result of which the possible influence of surface irregularities on the stability of a stacked dry stack building block is significantly reduced. As the protruding portion comprises ridges along opposing edges of the bottom and/or top surface, the dry stack building blocks can be stacked such that a front face and a back face of the stacked structure do not show any gaps between the building blocks, resulting in a seamless wall structure. The aligned through-holes can be filled with mortar, concrete or the like, through which the building blocks can be solidly connected with superjacent and/or subjacent building blocks. As a result, a dry stack construction with columns of mortar, concrete or the like therein is obtained, forming a very solid, strong and stable structure.

According to a preferred embodiment, the method further comprises embedding a reinforcing rod in mutually aligned grooves of one of the first and second building blocks and an adjacent building block, each groove being provided in at least one of bottom and top surfaces of each of said building blocks and extending in a longitudinal direction between end faces thereof. The reinforcing rod allows a row of building blocks to be interconnected. The interconnection on the one hand and the orientation of the groove and the rod perpendicular to the through-holes on the other enables a very stiff construction of dry stack building blocks. In particular, a groove which extends across an opening of the through-hole is beneficial, since the reinforcing rod becomes surrounded and therefore gets fixed by the mortar, concrete or the like poured in the through-holes.

According to a further preferred embodiment, the method further comprises aligning a conduit through-hole of at least one of the first and second building blocks with a conduit through-hole of a superjacent, subjacent and/or adjacent third building block. A particular advantage of these through-holes is that pipework can already be integrated with the wall during construction, so that no slots have to be milled into the constructed wall after construction. This saves valuable time at building site. According to a further preferred embodiment, , the method further comprises arranging a structural element in mutually aligned trenches of one of the first and second building blocks and an superjacent, subjacent and/or adjacent building block, each trench being formed by a space between legs of a U-shape of a cross-section of said building blocks. The structural element can be a reinforcing beam, rod, bar or the like, which is dimensioned such that it fits in the trenches of superjacent, subjacent and/or adjacent building blocks. The trench can be filled with mortar, concrete or the like through filling the through-holes that debouch into the trench, such that the mortar, concrete or the like is in contact with mortar or concrete in the through-hole, as a result of which an arch abutment can be formed, which further increases the strength and stiffness of the stacked wall structures. The invention further relates to a method for manufacturing a dry stack building block, preferably a dry stack building block according to the invention, comprising placing a form mould onto a contoured lower shaping plate for shaping a bottom surface of the dry stack building block, filling the form mould with a dry stack building block material substance up to its upper side, placing a contoured upper shaping plate for shaping a top surface of the dry stack building block into the substance at an upper side of the form mould, pressing the contoured upper shaping plate into the substance to a predetermined height, unloading the moulded pressed substance from the form mould, and drying the unloaded moulded pressed substance. The size accuracy needed to obtain a fixed size building block is realized by the lower and/or upper shaping plate, which can determine an exact height of the building block. Therefore no laborious post-processing is needed in order to obtain the size accuracy needed for dry stacking. A particular advantage of this method is that it saves both time and money, which is very important in a commodity industry like the building industry. The substance can be any known substance used for manufacturing building blocks, such as clay or concrete. More preferably, the substance is a mix of cement, expanded clay aggregate or pumice, sand, water and a liquid that impregnates the clay aggregate. Ideally, the diameter of the expanded clay aggregate or pumice particles is 4 to 10 mm. Most preferably, the ratio of the constituents of the mix is such that the density of the mix (and the dry stack building block) is less than 1000 kg/m ³ and the compressive strength of the dried dry stack building block is equal to or more than 10 N/mm ² . To meet these specifications, a mix of 7-10 % cement, 60-70 % clay aggregate or pumice, 15-25 % sand, 3-6 % water and 0.03-0.05 % impregnating liquid is preferred.

According to a preferred embodiment, the step of unloading the moulded pressed substance from the form mould comprises unloading the lower shaping plate, supporting the substance at its underside, unloading the form mould and unloading the upper shaping plate. A particular advantage of the combined use of a lower shaping plate and a supporting

According to a preferred embodiment, the method further comprises vibrating the form mould, and topping up the form mould with the substance after vibrating. The vibrating step allows the poured- in substance to sink in the mould. After vibrating the mould is topped up with the substance, so that it is ensured that the mould is completely filled with it.

The invention further relates to a mould system for carrying out a method for manufacturing a dry stack building block, preferably a method and/or a dry stack building block according to the invention, comprising a form mould, a contoured lower shaping plate serving for shaping a bottom surface of a dry stack building block, and an upper shaping plate for shaping a top surface of a dry stack building block, wherein the mould system is configured to fix a distance between the lower and upper shaping plate. Consequently, the lower and/or upper shaping plates determine an exact height of the dry stack building block. No laborious post-processing is therefore needed in order to obtain the size accuracy needed for dry stacking. Again, this saves both time and money. According to a preferred embodiment, at least one of the lower and upper shaping plates comprises a recessed portion for forming a protruding portion in at least one of a bottom and a top surface of a dry stack building block along opposing edges of said at least one surface. The protruding portion can for instance serve as a supporting surface for other dry stack building blocks to be stacked thereagainst. Additionally or alternatively, at least one of the lower and upper shaping plates comprises a protruding portion for forming a groove in at least one of a bottom and a top surface of a dry stack building block, wherein said groove extends in a longitudinal direction between end faces of the dry stack building block. This groove allows a row of building blocks to be interconnected by a reinforcing rod that is embedded in their grooves. The interconnection on the one hand and the orientation of the groove and the rod perpendicular to the through-holes on the other enables a very stiff construction of dry stack building blocks. In particular, a groove which extends across an opening of the through-hole is beneficial, since the reinforcing rod becomes surrounded and therefore gets fixed by the mortar, concrete or the like poured in the through-holes. Additionally or alternatively, at least one of the lower and upper shaping plates comprises a moulding portion for forming a channel or trench in at least one of a bottom and a top surface of a dry stack building block for receiving concrete and/or a structural member therein.

According to a preferred embodiment, the mould system further comprises a supporting plate for supporting the moulded pressed substance after the lower shaping plate has been unloaded. A particular advantage of a combined use of a lower shaping plate and a separate supporting plate is that cleaning of the lower shaping plate is eased and that the dried dry stack building blocks can be picked off from the supporting plate much easier than from the contoured lower shaping plate, as the supporting plate does not comprises the shaping protrusions of the contoured lower shaping plate. If the contoured lower shaping plate would also serve as the supporting plate for subsequent drying and storage of the dry stack building blocks, the dry stack building blocks could only be picked off the plate by lifting them vertically. Otherwise, the dry stack building blocks to be lifted would get damaged by the protruding parts of the contoured lower shaping plate.

Further advantages, features and details of the present invention are elucidated on the basis of the following description of preferred embodiments thereof with reference to the accompanying drawings, in which: figure 1 shows a perspective view of a preferred embodiment of an dry stack building block;

figure 2 shows a side view of the dry stack building block of figure 1 ;

figure 3 shows a top view of an embodiment of a mould system for manufacturing a dry stack building block of the invention;

figures 4 to 9 show side views of the mould system of figure 3;

figure 10 shows a perspective view of a various elements of an embodiment of a dry stack system;

figure 11 shows a perspective view of an embodiment of an assembled dry stack system; figure 12 shows a side view of a cross section of the dry stack system of figure 11 along line XII;

figures 13 shows a side view of a cross section of the dry stack system of figure 11 along line XIII;

figure 14 shows a side view of a cross section of the dry stack system of figure 11 along line XIII, wherein an inside is filled with a filler material;

figure 15 shows a side view of a wall portion comprising dry stack building blocks;

figure 16 shows a side view of a cross section of the wall portion of figure 15 along line XVI;

figure 17 shows a perspective view of another embodiment of a dry stack building block; figure 18 shows a side view of an embodiment of a prefabricated wall panel;

figure 19 shows a side view of a cross section of the prefabricated wall panel of figure 18; figure 20 shows a top view of a cross section of the prefabricated wall panel of figure 18; figures 21-24 show top view of various embodiments of a dry stack building block;

figure 25 shows a side of a cross section of a wall portion comprising dry stack building blocks;

Figure 1 shows a perspective view of a cuboidal dry stack building block 100, which comprises a bottom surface 101, a top surface 102, a front face 103, a back face 104, and two end faces 105 and 106. The top surface 102 has along its longitudinally extending edges a protruding portion in the form of two ridges 107 and 108.

In addition, two though-holes 109 and 110 are provided in the building block, which extend between bottom surface 101 and top surface 102. These through-holes 109 and 110 are to be aligned with through-holes of subjacent and/or superjacent building blocks and to be filled with mortar, concrete or the like, such that columns of concrete or the like are formed inside a stacked structure of dry stack building blocks 100. Thereto, through-holes 109 and 110 are arranged symmetrically with respect to a plane of symmetry of dry stack building block 100, which extends between bottom surface 101, top surface 102, front 103 and back face 104.

Further, six conduit through-holes 111-116 are provided in the building block, which extend between the bottom surface 101 and the top surface 102. Like through-holes 109 and 110, conduit through-holes 111-116 are also arranged symmetrically with respect to the aforementioned plane of symmetry of dry stack building block 100. Two of the conduit through-holes, i.e. conduit through- holes 113 and 114, are centred on a said plane of symmetry. Conduit through-holes 111, 112, 115 and 116 are halved along their length and centred at the end faces 105 and 106 of the dry stack building block 100, such that they constitute a fully enclosing conduit through-hole together with halved conduit-through-holes of adjacently arranged dry stack building block. As a result of the symmetric arrangement, conduit through-holes 111-116 can be aligned with conduit through-holes of subjacent and/or superjacent building blocks and can receive conduits and/or pipework therein, such that said conduits and/or pipework can run through a stacked structure of dry stack building blocks 100 along a straight line.

Moreover, dry stack building block 100 comprises a groove 117 in its top surface 101, which extends in a longitudinal direction 117a of dry stack building block 100. This groove is configured to receive a reinforcing rod therein, which is to be arranged in mutually aligned grooves 117 of adjacent dry stack building blocks 100.

Next, along perimeters of openings of through-holes 113 and 114 in top surface 102, top surface 102 is protruded to form closed-loop ridges 118 and 119 around the openings. Ridges 118 and 119 are configured to cooperate with the recesses 120 and 121 in bottom surface 101 around openings of through-holes 113 and 114 in bottom surface 101, which will be described in greater detail below.

Figure 2 shows a side view of dry stack building block 100 along line II of figure 1. Ridges 107 and 108 extending along edges of top surface 102 are clearly visible. Moreover, halved conduit through-holes 115 and 116, groove 117 as well as protruding portion 119 are clearly visible as well.

Figures 3 to 9 show an embodiment of a mould system 200, comprising a form mould 201, a contoured lower shaping plate 202 for shaping bottom surface 101 of dry stack building block 100, a contoured upper shaping plate 203 for shaping top surface 102 of dry stack building block 100. Form mould 201 may be configured such that it moulds for instance through-holes 109 and 110 and/or conduit through-holes 111-116 in dry stack building block 100. Mould system 200 can be made of steel and can be placed in a press machine, so that multiple blocks can be produced in a short period of time. As shown in figures 4-9, form mould 201 is filled with a custom-made mixed dry stack building block material substance 205 up until the upper side of form mould 201. Both form mould 201 and contoured lower shaping plate 202 are then vibrated with a special frequency, which collapses the custom-made substance 205 to a certain size. Thereafter, form mould 201 is again filled up to the top, after which contoured upper shaping plate 203 is pressed down to a predetermined position, thereby defining the height of dry stack building block 100. Figures 4, 6 and figures 5, 7 show form mould 201 being filled with custom-made substance 205 before and after pressing contoured upper shaping plate into custom-made substance 205, respectively.

Figures 4 and 5 show, however, side views of a cross-section of mould system 200 at the location of for instance conduit through-holes 113 and 114, whereas figures 6 and 7 show side views of a cross-section of mould system 200 at the location of for instance through-hole 109. After pressing contoured upper shaping plate 203 into the custom-made substance 205, contoured upper shaping plate 203 is kept fixed and contoured lower shaping plate 202 will be unloaded from mould system 200, as shown in figure 7A. At the same time, a supporting plate 206 is placed at the underside of mould system 200 to support form mould 201 and custom-made substance 205 therein. A particular advantage of a combined use of contoured lower shaping plate 202 and separate supporting plate 206 is that the cleaning of contoured lower shaping plate 202 is eased and that dried dry stack building blocks 100 can be picked off from supporting plate 206 much easier than from contoured lower shaping plate 202, as supporting plate 206 does not comprises the shaping protrusions of contoured lower shaping plate 202. If contoured lower shaping plate 202 would also serve as a supporting plate for subsequent drying and storage of dry stack building block 100, dry stack building blocks 100 could only be picked off the contoured lower shaping plate 202 by lifting them vertically. Otherwise, dry stack building blocks 100 would get damaged by the protruding parts of contoured lower shaping plate 202.

After placing supporting plate 206 under mould system 200, form mould 201 will be pulled up, as shown in figure 8. Custom-made substance 205 will remain in the form mould 20 las it is and contoured upper shaping plate 203 will be hoisted up afterwards, as shown in figure 9. Thereafter the mould is blocks will be transported on supporting plate 206 to a place where dry stack building blocks 100 are dried for approximately 24 hours. Figure 10 shows elements of a dry stack system 300, using three dry stack building blocks 301, 302 and 303, each being provided with a longitudinally extending groove 304, 305, 306, respectively, for receiving a reinforcing rod 326, two through-holes 307 and 308, 309 and 310, 311 and 312, and six conduit through-holes 313-318, 319-324, 325-330. Figure 11 shows an assembled dry stack system 300 wherein reinforcing rod 326 is embedded in grooves 304 and 305 of dry stack building blocks 301 and 302, and wherein through-hole 308 of dry stack building block 301 is aligned with through-hole 311 of superjacent dry stack building block 303 and through-hole 309 of dry stack building block 302 is aligned with through-hole 312 of superjacent dry stack building block 303. Similarly conduit through-holes 317-320 of building blocks 301 and 302 are aligned with conduit through-holes 327 and 328 of superjacent dry stack building block 303. Moreover, figure 11 clearly shows that, as a result of the protruding portion being formed as ridges 331 and 332 along longitudinal edges of top surfaces of dry stack building blocks 301 and 302, a seamless tessellation of front faces 333, 334, 335 of dry stack building blocks 301, 302, 303, respectively, forming dry stack system 300, is realized.

Figures 12 to 14 show cross-sectional side views of dry stack system 300, wherein figure 12 represents a cross-section along line XII of figure 11. In particular, figure 12 shows that conduit through-holes 317-320 of dry stack building blocks 301 and 302 are aligned with conduit through- holes 327 and 328 of superjacent dry stack building block 303, and that ridges 331 and 332 cause a space 336 between the top surface of dry stack building blocks 301, 302 and the bottom surface of dry stack building block 303. Figure 13 represents a cross-section along the line XIII of figure 11, wherein alignments of through-holes 309 and 312 is clearly shown as well as the resultant space 336 between a protruding portion 337 around an opening in the top surface of dry stack building block 302 around through-hole 309 and a recessed portion 338 in the bottom surface of superjacent dry stack building block 303 at the location of through-hole 312. Figure 14 represents the cross- sectional view according to figure 13, wherein through-holes 309 and 312 are filled with custom- made mortar 339, and wherein reinforcing rod 326 is embedded in said custom-made mortar 339 at least at location of the through-holes. Protruded portion 337 has a slanted side surface 337a and recessed portion 338 has a correspondingly slanted side surface 338a. A particular advantage of correspondingly slanted side surface 337a and 338a of protruding and recessed portions 337 and 338, respectively, is that it further facilitates the collapse of the poured-in mortar, concrete or the like in the through-holes.

Figure 15 shows a wall portion 400 near an opening 401 for instance a door or window, which comprises dry stack building blocks 402-406, each of which has a U-shaped cross-section, wherein between the legs 407 and 408 of the U-shape a space 409 is formed for receiving a reinforcing beam 410. Dry stack building blocks 402-406 also known as lintel blocks. Figure 16 represents a side view of a cross-section of wall portion 400 of figure 15 along line XVI, wherein space 409 between the legs 407 and 408 and reinforcing beam 410 therein are clearly visible. Moreover, a tapering angle of a side surface 411 of recessed portion in the bottom surface of the superjacent dry stack building block near its through-hole is larger that a tapering angle of a side surface 412 of a protruding portion in the top surface of the subjacent dry stack building block. Specifically, conically tapered recessed and protruding portions, wherein a tapering angle of the protruding portion is larger than a tapering angle of the recessed portion, allow the poured-in mortar, concrete or the like to easily sink in the through-holes while at the same time achieving a high fill factor. Figure 17 is a perspective view of dry stack lintel block 403, wherein the excavated space 409 for receiving reinforcing beam 410 is shown.

Figure 18 shows a prefabricated wall panel 500 comprising a plurality of dry stack building blocks 501 which are stacked in stretcher bond. The wall panel further comprises a prefabricated concrete beams 502, 503 with reinforcing bars 507 therein as well as vertical reinforcing bars 505 and horizontal reinforcing rods 506. Prefabricated panel 500 is manufactured as follows. First, prefabricated concrete beams 502, 503 are manufactured. Thereafter, dry stack building blocks 501 are stacked onto prefabricated concrete beam 502. In each layer of dry stack building blocks 501, a horizontal reinforcing rod 506 is placed into grooves of dry stack building blocks 501. Then, formwork is placed on top of the upper dry stack building blocks 501, on top of which

prefabricated concrete beam 503 is placed. Next, reinforcing bars are stuck into columnar holes 508, formed by the aligned through-holes of the stacked dry stack building blocks 501, and into the upper prefabricated concrete beam 503. Subsequently, custom-made mortar, concrete or like is poured into columnar holes 508 and the upper prefabricated concrete beam 503, as a result of which the interior of the prefabricated wall panel 500 is filled with columns of mortar, concrete or the like. Next, the lower prefabricated beam 502 can be lifted with a fork-lift truck and transported to a drying site, after which a new prefabricated wall panel 500 can be manufactured. At the drying site, prefabricated wall panel 500 can be finished, e.g. it can be plastered. After drying, prefabricated wall panel 500 can be transported to a building site, where it can be erected by pulling reinforcing bars 507 of the lower prefabricated concrete beam 502, so that no destructive forces are exerted on the panel 500.

Figure 19 shows a cross-sectional side view of prefabricated wall panel 500, wherein prefabricated concrete beams 502, 503 as well as columnar hole 508, formed by the aligned through-holes of the stacked dry stack building blocks 501, and the vertical reinforcing bars 505 are clearly visible. It can be seen as well that vertical reinforcing bars 505 are bent at one extreme end thereof to hook lifting means thereto in order to lift prefabricated wall panel 500. Moreover, vertical reinforcing bars 505 are connected to lower prefabricated concrete beam 502 at another extreme end thereof in order to lift prefabricated wall panel 500 without exerting forces onto the stacked structure of dry stack building blocks 501. Figure 20 is a cross-sectional top view of preventable foot panel 500, wherein columnar hole 508, formed by aligned through-holes of the stacked dry stack building blocks 501, and the vertical reinforcing bars 505 are clearly visible. Also protruding portions 509 in the top surface of dry stack building blocks 501 around columnar holes 508 are shown.

Figure 21 shows a half dry stack building block 600, which is required for stacking dry stack building blocks in stretcher bond. Figure 22 shows a dry stack building block 700, having an excavation 701 in one of its end faces, which makes its suitable for installing a window frame therein. As dry stack building block 700 is open at its end face, concrete will sink into this opening during pouring (custom-made) mortar, concrete or the like in the columnar holes, formed by the aligned through-holes of the stacked dry stack building blocks. As a result, window frames can be fixed both easily and tightly.

Figure 23 shows a dry stack building block 800 which is cut in half along its length. This block is suitable for dry stack walls that support a floor, as it isolates the floor thermally from the outside of the building, so that a thermal bridge is avoided. Figure 24 shows a dry stack building block 900, which is suitable for forming a T-junction. This block avoids superjacent side joints being aligned to each other when forming a T junction in e.g. a stretcher bond dry stack structure.

Figure 25 shows a cross-sectional view of a wall portion 1000, comprising a stacked structure in which a floor 1001 is supported by a dry stack wall of dry stack building blocks 1002. Dry stack building blocks 1002 comprise conduit through-holes 1003 for receiving pipework and/or cables 1004 therein. A specific L-shaped dry stack building block 1005 comprises a conduit through-hole which extends between a front/back face and a bottom surface of dry stack building block 1005, so that pipework and/or cables 1004 can be enter/exit the wall portion 1000 in a direction

perpendicular to a stacking direction of the dry stack building blocks 1002 and 1005.

The present invention is not limited to the above described preferred embodiment; the rights are defined by the claims, within the scope of which many modifications can be envisaged.