FIELD OF THE INVENTION

The invention relates to the field of wave retarding constructions in general. The invention may well be used in groynes and bank revetments. Wave retarding constructions in general have an open structure absorbing part of the water/wave energy when the water flows against and/or along and/or through the open structure.

In a water - like a lake, a sea or a waterway - wave retarding constructions are frequently used to reduce the forces of the water by retarding the flow of water and/or the waves. The invention may be used in any type of water as a wave retarding construction having - inherent to its wave retarding function - an open structure. In waterways - like rivers and canals - wave retarding constructions are frequently used as so called ‘river training structures’. ‘River training structures’ may be grouped in a) bed fixation and bottom vanes, b) longitudinal river training structures, and c) transverse river training structures. Structures of groups b) and c) frequently have an open surface structure to retard water/waves. River training may have one or more objectives like: maintaining a depth of the navigation channel of the waterway for vessels and ships, increasing safety against flooding, improving efficiency of sediment transport, minimising or reducing bank erosion by stabilizing the course of the flow, and/or directing the flow to a desired stretch.

Perhaps one of the best-known examples of a river training structure is a groyne. Referring to Wikipedia, “A groyne (in the U.S. groin), built perpendicular to the land, is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. “ This Wikipedia definition may suggest that groynes extend transverse to the bank or shore, but this is incorrect. Groynes may also be arranged in the water, at a distance from the bank or shore, and extend in the longitudinal direction of the of the bank or shore. The invention may be used in both types of groynes as well as other types of groynes. A groyne may also be used as a weir.

More specifically, the invention relates to a building component for a wave-retarding construction, a wave-retarding construction comprising a plurality of building components according to the invention, use of a plurality of building components according to the invention in a bank revetment or groyne, a mould and mould assembly for manufacturing a (plurality of) building component(s) according to the invention, and a method for manufacturing a (plurality of) building component(s) according to the invention.

The invention may be used in waterways - such as rivers or canals - as a river training construction and/or as a groyne or bank revetment.

BACKGROUND OF THE INVENTION

Historically wave retarding constructions comprise plurality of blocks of concrete or stone, like natural or artificial stone, which blocks are randomly arranged so that there are openings between the blocks allowing water to enter between the blocks so that water/wave energy is absorbed. Wave retarding constructions may also comprise wood or a combination of wood and blocks arranged to provide openings for absorbing water/wave energy.

In recent decades, wave retarding constructions have been made also with concrete blocks of a very specific design that further improves the wave-retarding characteristics. An example of such concrete blocks is the block as shown in figures 3-5 of WG-2004/009910, which blocks are marketed under the tradename Xbloc®. In larger dimensions these blocks are used in coastal breakwaters, in smaller dimensions these blocks are used in river groynes.

Although not very complicated, the manufacturing of these blocks is not very easy, and consumes a lot of time as well as quite a lot of material in formwork and concrete.

A further general problem in building constructions is presently the environmental footprint, like the carbon footprint.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an alternative building component. It is a further object to provide an alternative building component overcoming or reducing one or more of the problems associated to prior art building components for wave retarding constructions.

According to a first aspect of the invention, one or more of the above objects are achieved by providing a building component for a wave-retarding construction, which component comprises:

- a concrete slab extending in a slab plane,

- a wooden pin wherein the concrete slab has a central part and a plurality of at least three arms extending from the central part in the slab plane; wherein the wooden pin extends transverse to the slab plane through the central part of the concrete slab to provide:

- a first projection projecting from the central part in a first direction, and

- a second projection projecting from the central part in a second direction, the second direction being opposite to the first direction.

As is also the case with the projections of the building blocks of figures 3-5 of WO- 2004/009910, the first and second projection of the wooden pin and the at least three arms extending from the slab together provide an engagement system that allows a plurality of such building components to form a wave retarding construction consisting of a plurality of inter-engaging building components. The wave retarding construction formed by the building components according to the invention may be a revetment, such as the underwater part of a revetment, of a for example a bank, a dam, a groyne etcetera. It is however also possible to use the building components according to the invention not only for revetment but also as a dike body so that a plurality of such building components constitutes a groyne or dam, or - according to a further embodiment to be discussed further below - at least the underwater part of a groyne or dam which is below water level. Using the building component according to the invention underwater, prevents the wooden pin from rotting away. When used underwater, the building component according to the invention has so to say an about endless lifetime.

Further, as is also the case with the projections of the building blocks of figures 3-5 of WO-2004/009910, the first and second projection of the wooden pin and the at least three arms of the building component according to the invention provide open spaces between building blocks and inside a pile of building blocks. These open spaces allow water to enter so that energy contained in flowing water is absorbed, or said differently, waves and/or waterflow is retarded. Using a wooden pin instead of two concrete projections as in WO- 2004/009910, reduces the amount of concrete in a building component with about 30%, which in turn reduces the so called CO2 footprint. The wooden pin even further reduces the CO2 footprint as the wood used in the building component will not be become subject of waste incineration. The use of the wooden pin furthermore permits a considerably simpler manufacture of the building component.

According to a further embodiment of the first aspect, the wooden pin may be a piece of river wood. ‘River wood’, in Dutch ‘rivierhout’, is essentially dead trees arranged underwater in a waterway - like a river, canal, etcetera - to restore the underwater fauna. Referring to https://www.rijkswaterstaat.nl/water/waterbeheer/waterkwalit eit/maatregelen- waterkwaliteit/rivierhout#eten-en-gegeten-worden , the trees form, as it were, a coral for invertebrates that can just be seen with the naked eye, such as tube damselfly larvae, amphipods and mayflies. These animals are in turn eaten by fish such as the chub, the barbel and the snape. They use the branches and roots of the tree for shelter, spawning and forage.

According to another further embodiment of the first aspect, the wooden pin may be a piece of roundwood. Roundwood is in general timber which is left as small logs, not sawn into planks or chopped for fuel. Roundwood may originate from the trunk of a tree, i.e. the stem and main wooden axis of the tree, or from a branch. Roundwood may comprise the bark (=outer layer) and/or bast (= layer between the bark and the wood), may comprise parts of the bark and/or bast, but may also be without bark or without bark and bast in case of a peeled roundwood. The circumference of a piece of roundwood is round in a general sense, but mathematically it is not a circle.

According to another further embodiment of the first aspect, the diameter of the wooden pin(/piece of river wood/piece of roundwood) may be in the range of 5 to 17 cm, such as in the range of 8 to 14 cm. According to a first example, the diameter of the wooden pin may be in the range of 5 to 15 cm. According to a second example, the diameter of the wooden pin may be in the range of 8 to 12 cm.

According to another further embodiment of the first aspect, in which the concrete slab has, viewed transverse to the slab plane, a slab thickness, the diameter of the wooden pin may be of the same order of magnitude as the slab thickness. The diameter of the wooden pin may for example be in the range of 75% to 125% of the slab thickness, such as in the range of 75% to 110% of the slab thickness.

According to another further embodiment of the first aspect, wherein the plurality of arms consists of three, four, five or six arms.

According to another further embodiment of the first aspect, each arm has a free outer end, and, measured along the slab plane, the free outer ends of adjacent arms may be arranged at a distance in the range of 25 cm to 50 cm.

According to another further embodiment of the first aspect, the plurality of arms consist of four arms arranged with an angular spacing of 90° around the central part, each arm having a free outer end, and, measured along the slab plane, the free outer ends of adjacent arms are arranged at a distance in the range of 25 cm to 50 cm. According to another further embodiment of the first aspect, the building component defines a smallest bounding sphere with a radius in the range of about 15 to about 35 cm, such as a radius in the range of about 20 to about 25 cm or a radius of about 25 cm.

According to another further embodiment of the first aspect, the building component defines a smallest bounding cube with edges each having a length in the range of about 20 to about 50 cm, such as a length in the range of about 30 to about 40 cm or a length of about 25 cm.

Referring to Wikipedia - https://en.wikipedia.org/wiki/Smallest-circle_problem - the smallest-circle problem is the mathematical problem of determining the smallest bounding circle that contains all given points on a 2-dimensional plane or that contains a 2-dimensional object. Similar for a 3-dimensional object - like the inter-engaging building components used in the invention -, a smallest bounding sphere or a smallest bounding cube containing the object can be determined. Although the known inter-engaging building components used for breakwater structures are very large and heavy - having a smallest bounding sphere with a radius of about 1 meter or more -, it has been found that for waterway purposes the interengaging building components may be much smaller. This facilitates transportation and manipulating these building components considerable. Smallest bounding spheres with a radius of less than about 35 cm and/or smallest bounding cubes with an edge length of less than about 50 cm, allow construction of a wave retarding construction by just dumping these blocks without requiring heavy equipment. Construction of a wave retarding construction with building components of these dimensions may be from land by means of a one or more vehicles and/or from water by means of one or more vessels. The vehicle or vessel respectively, may have one or more of: a side dumper, a hopper barge, a clamshell crane.

According to a second aspect of the invention, one or more of the above objects of the invention are achieved by providing a wave-retarding construction comprising a plurality of the building components according to the first aspect of the invention.

According to a further embodiment of the second aspect, the plurality of building components is arranged under water, i.e. below the water level such as at some distance below the water level. By arranging the building components according to the invention under water, decay of the wooden pins due to for example rotting is prevented. All building components according to the invention in a construction according to the invention may thus be arranged under water, in other words all building components with - according to the invention - a wooden pin may, in a construction according to the invention, be arranged up to a level of at most the water level or - see below - another level which is lower than the water level.

The building components may be arranged below the AL-level. AL-level stands for Agreed Lower level. In case the water level of a river is concerned, this is also called the ALR-level (=Agreed Lower River level). When building a construction in water - like in a waterway, in sea, in a lake etcetera - having varying water levels, there are in general some assumptions involved in relation to the water level. The contractor and the client do need some agreement concerning the range in which the water level may fluctuate as this will have impact on how the construction is to be designed and build. These values may be obtained from authorities or institutions monitoring the water level, and safety margins may be applied to these values. On the end there is some lower level about which the contractor and client have a mutual understanding that this can be considered as the lower level. This is the so called AL-level. The AL-level can be seen as a design criterion.

According to another further embodiment of the second aspect, the plurality of building components is arranged lower than 90% of a predefined reference level of water, such as in the range of 75% to 90% of the predefined reference level , for example up to at most 75% or 80% or 85% or up to at most any other percentage of the predefined reference level. The predefined reference level may for example be the water level, the AL-level, or any other level of water. When expressing a maximum height of the plurality of building components as a percentage of any predefined reference level, this predefined reference level, such as the water level or AL-level, may according to a further embodiment be expressed with respect to the bottom of the water, i.e. when the distance from the bottom the water to the AL-level or water level is for example 2 meters and the plurality of building components is arranged lower than 90% of the AL level respectively water level, this means that the plurality of building components is arranged below the level of 180 cm above the bottom.

Arranging the building components underwater at some distance below the water level prevents the wooden pins from rotting away without conservation of the wood being required, which would make the wooden pins environmentally harmful and less suitable for the water fauna.

According to an alternative or additional further embodiment of the second aspect, the plurality of building components is arranged up to at most 10 cm below a predefined reference level - such as the water level or the AR level -. The plurality of building components may for example be arranged up to at most 25 cm below the predefined reference level - such as the water level or the AR level The plurality of building components may according to a further example be arranged up to at most 40 cm below the predefined reference level - such as the water level or the AR level

According to a further embodiment of the second aspect, the wave retarding construction further comprises a plurality of building elements arranged on top of the plurality of building components to increase the height of the wave retarding construction in vertical direction. The building elements may for example increase the height of the wave retarding construction to about or to above the water level. In a further embodiment the building elements may have a shape and/or dimensions similar to the building components according to the first aspect of the invention.

According to another further embodiment of the second aspect, the wave retarding construction is one or more of: a bank revetment, a groyne, a groyne revetment, a river training structure, a revetment of a river training structure.

According to a third aspect of the invention, one or more of the above objects of the invention are achieved by the underwater use of a plurality of building components according to the first aspect of the invention. The underwater use being use at some distance below the water level or below the AL-level. This some distance may in practise be at a distance of 10 cm or more below the water level/AL-level, such as

- at distance of at least 20 cm below the water level or AL-level or

- at a distance of at least 25 cm below the water level or the AL-level or

- at distance of at least 40 cm below the water level or AL-level.

According to a fourth aspect of the invention, one or more of the above objects of the invention are achieved by using a plurality of building components according to the first aspect of the invention in one or more of: a river training structure, a bank revetment or a groyne. A bank revetment may be arranged along a water - like along a river or along a canal or along a lake or along a sea -. A groyne may be arranged in a water - like in a river or in a canal or in a lake or in a sea -, extending in length direction of the bank/shore at a distance of said bank/shore, transverse to the bank/shore or in any other direction with respect to the bank/shore.

According to a fifth aspect of the invention, one or more of the above objects of the invention are achieved by providing a mould for manufacturing a building component according to the first aspect of the invention; wherein the mould comprises a mould cavity defined by a horizontal mould wall and a vertical mould wall configured to define a circumferential side wall of the concrete slab to be manufactured by pouring concrete in the mould cavity; wherein the mould further comprises a vertical hole provided:

- in the horizontal mould wall and

- at the centre of the central part of the concrete slab to be manufactured by pouring concrete into the mould cavity; wherein the hole is configured such that when:

- a lower part of the wooden pin is inserted in the hole,

- subsequently concrete has been poured into the mould cavity, and

- the poured concrete has been allowed to cure, the building component according to the first aspect of the invention is obtained with an upper part of the pin projecting from an upper surface of the slab and the lower part of the pin projecting from a lower surface of the slab. The lower part of the pin provides the second projection and the upper part of the pin provides the first projection, or - vice versa - the lower part of the pin may provide the first projection and the upper part of the pin may provide the second projection.

According to a sixth aspect of the invention, one or more of the above objects of the invention are achieved by providing a mould assembly comprising a plurality of moulds according to the fifth aspect of the invention.

According to a seventh aspect of the invention, one or more of the above objects of the invention are achieved by providing a method of manufacturing a building component according to the first aspect of the invention, the method comprising the sequential steps of:

- providing a mould according to the fifth aspect,

- inserting a wooden pin into the hole;

- pouring concrete into the mould cavity;

- curing the poured concrete; and

- removing the building component obtained from the mould.

According to an eight aspect of the invention, one or more of the above objects of the invention are achieved by providing a method of simultaneously manufacturing a plurality of building components according to the first aspect of the invention, the method comprising the sequential steps of:

- providing a mould assembly according to the sixth aspect of the invention, the mould assembly having a plurality of moulds, the plurality of moulds corresponding to the plurality of building components to be manufactured simultaneously; - inserting wooden pins into the holes of the plurality of moulds;

- pouring concrete into the mould cavities of the plurality of moulds;

- curing the poured concrete; and

- removing the building components obtained from the mould assembly.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be explained further with reference to the drawings. In these drawings:

Figure 1 shows a building component according to the invention. In Figure 1 , figure 1A shows a side view according to the arrow A in figure 1 B, figure 1 B shows a front view, figure 1C shows a side view according to arrow C in figure 1 B, and figure 1 D shows a perspective view.

Figure 2 shows schematically a cross section of a wave retarding construction according to the invention, which construction is arranged in a water arranged with the building components according to the invention below water level.

Figure 3 shows schematically a mould according to the invention and a method of manufacturing one or more building components to the invention. In figure 3, figure 3A shows part of the mould, figure 3B shows a complete mould, figure 30 shows the mould of figure 3B with wooden pins inserted into the holes in the bottom of the mould, figure 3D shows the mould of figure 30 after concrete having been poured into the mould cavities, and figure 3E shows the removal of the building components obtained from the mould.

DETAILED DESCRIPTION OF THE EMBODIMENTS

This building component according to the invention is in fact essentially the same as the concrete element shown in figure 3 of WO-2004/009910, except that in the building component according to the invention the concrete projections (2 and 3) of figure 3 of WO- 2004/009910 have been replaced by a single wooden pin, which pin has been put through the central part (1) of figure 3 of WO-2004/009910 and projects with a first projecting part of the wooden pin from one side of the central part (1) of projecting figure 3 of WO-2004/009910 and projects with a second projecting part of the wooden pin from the other side of the central part (1) of figure 3 of WO-2004/009910. Further, in an embodiment of the invention the building component according to the invention is much smaller than concrete element of figure 3 of WO-2004/009910. Although WO-2004/009910 does not mention values for the distance between the pointed ends of adjacent arms (4) of figure 3 of WO-2004/009910, this distance is in practise in the range of 1.5 to 2.5 meter, and according to an embodiment of the present invention this distance is in the range of 25 to 50 cm.

Now turning to Fig. 1 of the present application, this figure shows a building component according to the invention in four views, the side view of Fig. 1A, the front view of Fig. 1 B, the side view of Fig. 1 C, and the perspective view of Fig. 1 D.

As can be seen in Figs. 1A, 1 B, 1C, and 1 D, the building component 1 according to the invention comprises a concrete slab 2 extending in a slab plane P, and a wooden pin 4. The slab plane P is shown as a dashed line in Fig. 1A and Fig. 1 C, and extends parallel to sheet of paper in the Fig. 1B. The concrete slab has a central part 5 and a plurality of arms 6- 9 extending from the central part in the slab plane P. In Fig. 1B the central part 5 has been indicated as a octagonal dashed line representing so to say the circumference of the central part 5. From this central part 5 the arms 6-9 extend in the slab plane P, or said differently the arms 6-9 project from the central part in the direction of the slab plane P. The wooden pin 4 extends transverse to the slab plane P and extends through the central part 5 of the concrete slab to provide a first projection 10 projecting from one surface 38 of the central part 5 in a first direction - see arrow I in Fig. 1 A - and a second projection 11 projection from a surface 37 opposite said one surface 38 in a second direction - see arrow II in Fig. 1B -, the second direction II being opposite to the first direction I.

The wooden pin 4 may according to a further embodiment of the invention be a piece of so called river wood and/or a piece of roundwood. As shown in Fig. 1 , the wooden pin may for example consist of the wood (core) 21 with the bark 20 still around the wood 21. The bark may still be fully present (not shown) or may be partly present as shown in Fig. 1. In Fig. 1D the bark 20 is shown in dark grey, whilst the wood 21 is shown in light grey.

According to an embodiment of the invention the wooden pin may have a diameter D - indicated in Fig. 1C - in the range of 5-15 cm, such as in the range of 8-12 cm. As will be understood, the term diameter does in this invention not mean that the wooden pin has a circular cross-section. Although the cross-section of the wooden pin may be precisely circular, it can be seen in Fig. 1B and Fig. 1 D that the cross section may have an irregular not precisely circular shape.

As is indicated in Fig. 1 C, the concrete slab has a slab thickness T. As can be seen in Fig. 1C as well as in the Figs. 1 A, 1 B, and 1 D, the diameter of the wooden pin may - according to an embodiment of the invention - be of the same order of magnitude as the slab thickness T. The diameter D of the wooden pin may for example be in the range of 75% to 125% of the slab thickness T, such as in the range of 75% to 110% of the slab thickness T.

Although Fig. 1 shows a building component having four arms 6, 7, 8 and 9, it is according to the invention also conceivable that the number of arms is three, five or possibly six. When the number of arms becomes too small or too large, the building components will not properly inter-engage when randomly placed onto each other to form for example a revetment or a groyne.

As already addressed, the building components according to the invention may according to a further embodiment be much smaller than the elements of figure 3 of WO- 2004/009910. These much smaller dimensions may be expressed in different manners which may be supplemental to each other. A first manner of expressing the (relatively small) dimensions is by requiring the distance Z - see Fig. 1B - between the free outer ends 12 of adjacent arms 6, 7 being in the range of 25 cm to 50 cm. Another manner of expressing the (relatively small) dimensions is by requiring that the smallest bounding sphere has a range of about 15 to about 35 cm, for example a radius in the range of about 20 to about 25 cm or a radius of about 25 cm. Still another manner of expressing the (relatively small) dimensions is by requiring that the smallest bounding cube has edges having a length in the range of about 20 to about 50 cm, for example a length in the range of about 30 to 40 cm or a length of about 25 cm.

Fig. 2 shows a wave-retarding construction 100 according to the invention. This wave retarding construction 100 is arranged on the bottom 104 of a water, such as a sea, a lake, a river, a canal, etcetera. The wave retarding construction 100 comprises a plurality 3 of building components 1 according to the invention. Each of these building components is like the one shown in Fig. 1 and has a wooden pin 4, indicated in black, and a concrete slab 2 with four arms (not indicated in figure 2). As can be seen in Fig. 2 the building components 2 of the plurality 3 of building components may be arranged in a random fashion. When building the construction one may for example simply dump the building components into the water for example by means of a gripper holding multiple of building components at the same time and releasing them together when at or above the correct position.

As can be seen in Fig. 2 all building components 1 according to the invention may in a wave retarding construction according to the invention all be arranged below the water level 101 , in other words the building components 1 according to the invention in a wave retarding construction according to the invention will be arranged up to at most the water level, for example up to at most a level 103 at some distance below the water level 101.

In order to ensure that the wooden pin is under water, the building components 1 according to the invention are according to a another further embodiment of the invention arranged up to at most 90% of the water level 101, such as up to at most in the range of 75% to 90% of the water level, which water level 101 may be measured with respect to the bottom 104 of the water. By taking the maximum height of the plurality of building components at a value lower than 90% of the water level, like at 80% or 75%, one can anticipate variations in water level 101 without the wooden pins of the building components surfacing above water.

In practise the contractor and the client, in general the party giving the assignment to the contractor, will find agreement on an expected lower water level, called the AL-level (= Agreed Lower level). Then all building components 1 according to the invention will be arranged below the AL-level, in other words the building components 1 according to the invention in a wave retarding construction according to the invention will be arranged up to at most the AL-level. To take into account a safety margin, the building components 1 according to the invention may according to a further embodiment of the invention be arranged up to at most 90% of the AL-level 102, such as up to at most in the range of 75% to 90% of the AL- level 102, which AL-level 102 may be measured with respect to the bottom 104 of the water. This results in a distance Q between the maximum level 103 at which a building component 1 is arranged and the AL-level 102.

In case the water level is quite stable or in case no AL-level has been agreed on, the distance Q may be with respect to the water level 101 or with respect to any other (predefined) reference level. Taking this into account and taking into account the preceding discussion in relation to Fig. 2, the distance Q may be at least 10% of the reference level (i.e. the water level, the AL-level, or any other reference level), which reference level may be measured with respect to the bottom 104 of the water. The distance Q may for example be any percentage in the range of 10% to 25%.

Instead of expressing the distance Q as a % of any reference water level, Q may also be expressed as a distance in centimeters below any reference level. In another alternative or supplementary embodiment of the construction according to the invention, the distance Q is 10 cm or more below the reference level - like the water level, the AL-level or any other predefined level - . This distance Q may in a further embodiments be at least 20 cm or at least 25 cm or at least 40 cm below the reference level - like the water level, the AL-level or any other predefined level

In a wave retarding construction 100 according to the invention, the plurality 3 of building components 1 according to the invention may be topped by a plurality of other building components 105 in order to raise the wave- retarding construction up to above the water level, see Fig. 2. These other building components 105 will further be called building elements in order to avoid confusion with the building components 1 according to the invention. Except for the wooden pin 4, these building elements 105 may in shape for example be similar to the building components 1 according to the invention. Also in dimensions, the building elements 105 may be similar to the building components 1 according to the invention. In the building elements 105 the wooden pin may be replaced by another pin which is not susceptible to rotting, like a pin of concrete, of plastic, or of any other suitable material. In case of a concrete pin, this may result in a building element like shown in figure 3 of WO-2004/009910. Also these building elements 105 may be arranged in a random fashion.

Figure 3 shows an example of a mould/mould assembly for manufacturing one or more of building components 1 according to the invention and illustrates a method for manufacturing one or more of said building components according to the invention. It is to be noted that the mould/mould assembly according to the claims of this application and/or according to Fig. 3B can be used for manufacturing building elements 105 with a pin of concrete, of plastic, or any other material. Similar it is to be noted that the method according to the claims of this application and/or according to Fig. 3A-E can also be used for manufacturing building elements 105 with a pin of concrete, of plastic, or any other material.

Fig. 3A shows a part of the mould assembly 30 according to the invention. The part in Fig. 3A is the horizontal mould wall 32 provided with - in this example - nine vertical holes 35. The vertical holes 35 serve to receive the lower part 10 of a wooden pin 4 of the building component 1 according to the invention or to receive a lower part of any pin of a building element 105. As is or will become clear the mould assembly 30 of Fig. 3 consists of 9 moulds 40 according to the invention. The number of moulds 40 in one mould assembly 30 may be more or less than the nine shown in Fig. 3.

In Fig. 3B the mould assembly 30 with in this example nine moulds 40 has been built up completely by adding the circumferential side walls to obtain the mould cavities 31. In this example each circumferential side wall of a mould cavity comprises a set of two first side walls 34 and a set of two second side walls 33, the second side walls 33 extending transverse to the first side walls. Each of the side walls 33, 34 is provided with a projection 36 projecting from the side wall 33, 34 into the mould cavity 31. These projections 36 are configured to form the indentations 22 between adjacent arms 6, 7, 8 and 9, see Figs. 1B and 1 D. The side walls 33, 34 may for example be made of wood or any other material suitable for in a mould for moulding concrete. As shown in the example of Fig. 3 the side walls 33 and 34 may be provided with cooperating slits allowing the side walls 33 and 34 to be assembled into matrix like grid of transverse wall. When discharging building components moulded or building elements moulded, the grid of side walls 33 and 34 may be dissembled, see Fig. 3E.

When the mould assembly respectively the moulds have been built up, as shown in Fig. 3B, the wooden pins 4 of the building components 1 according to the invention or the pins of the building elements 105 are inserted into the holes 35. After having been inserted into the holes, the lower parts 10 of the pins extend inside a respective hole 35, and the rest of the pins project upwards, see Fig. 3C which shows the pins in dark grey and the mould in light grey.

Next, concrete is poured into the mould resulting in the mould cavities 31 filled with concrete, see Fig. 3D in which the concrete is shown in medium grey.

Once the concrete has been sufficiently or fully hardened, the side walls 33 and 34 can be removed and allowing the obtained building components 1 according to the invention or the obtained building elements 105 to be discharged from the mould. In case the side walls 33 and 24 are given a sufficient taper, the slab 2 will have a sufficient taper - see Figs. 1 A and 1 C, and the side walls 33 and 34 will not need to be removed for discharging the building components 1 respectively building elements 105. The building components 1 respectively building elements 105 can then be discharged by just turning the mould sufficiently side wards or up side down.