BACKGROUND OF THE INVENTION

The invention relates to a block, particularly formed out of concrete, for covering a water-retaining or water guiding slope, such as a bank, coast or dike, including spillways, for the protection of said slope against wave attacks and water flows. The invention furthermore relates to an assembly of such blocks and to a covering. The invention furthermore provides a method for manufacturing an assembly of blocks and a filter mat. Such blocks and coverings formed therewith have long been used. For instance a covering may have been built up using a geotextile such as filtering cloth, a layer of granular material thereon, and on top of that a series of concrete blocks, straight parallelepiped, that are laid in a stretcher bond. The use of basalt column-like concrete blocks is also known.

In European patent application 1.275.784 a particular shape of blocks is shown and described, which blocks substantially have the shape of a straight regular hexagonal prism, albeit that the walls slightly taper (approximately 0.5%) in order to be releasable from the mould. The circumferential surface comprises six side surfaces, to be divided into three relatively flat side surfaces and three relatively recessed side surfaces that are provided with a vertically through-going main recess, alternately arranged. A block based thereon is the Rona®ton+. The flat side walls can be considered to form the sides of said prism.

The top surface of this known block comprises a flat, hexagonal central plane and six surfaces that slantingly descend from the sides of said central plane, and that end up in the circumferential surface. At the location of the six corner areas of each block substantially U-shaped protrusions formed thereon and projecting from said prism are provided, which in a lowermost part form contact surfaces for cooperation with contact surfaces of adjacent blocks. The protrusions each have two vertical ribs, which in between them form an elongated, upwardly extending recess, that starts at a distance from the bottom surface, at the location of a step, and ends at a broad distance from the upper surface.

The blocks are formed in a mould and after removal of the mould are placed against each other in order to form an assembly or group of for instance four series of four blocks, that can be picked up by a machine, wherein the blocks in each series are placed with the side surfaces against each other. In that case the orientation of each block is the same, so that each time a relatively flat side surface of the one block abuts a relatively recessed side surface of the other block. Together the blocks form a honeycomb bond. The groups or assemblies are picked up in the work and placed one by one on the subsoil, in series that extend in horizontal direction along the slope, wherein the said series of blocks also run in that direction.

After placing the groups of blocks grit is spread over the blocks, in order to end up in the main recesses and also in the recesses in the corner areas. The grit (usually grit of 6-21 mm) in the corner areas may cooperate in the prevention of a relatively vertical movement of a block with respect to the adjacent blocks. The main openings have to comply with the standard that a ball with a cross-section of 5cm may not with its largest dimension end up in said opening. The main openings mainly serve to prevent too high a dynamic water pressure under the blocks. A permeability of 8-15% is feasible. The grit in the main recesses also has a part in stopping underlying granular material, preserving sufficient flow-through surface for the water flowing out upwardly.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a block of the type mentioned in the preamble which in a covering in a bond with several similar blocks and with washed in grit has an increased degree of interlocking therewith. It is an object of the invention to provide a block of the type mentioned in the preamble which in a covering provides sufficient permeability with openings between the blocks that also in case of slight mutual displacement between two blocks can remain within standards. It is an object of the invention to provide a block of the type mentioned in the preamble that has been improved regarding one or more aspects with respect to the block according to the said European patent application.

It is an object of the invention to provide a block of the type mentioned in the preamble that has been improved regarding one or more aspects with respect to known blocks, particularly the block according to the said European patent application.

At least one these objects is achieved according to the invention with a block, particularly of concrete, for with a number of other, particularly identical blocks, forming a bond for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, wherein the block comprises a lower surface, an upper surface and a circumferential surface, wherein the circumferential surface of the block is provided with vertical recesses that extend to at least near the upper surface, preferably up into the upper surface, preferably at the location of a highest surface of the upper surface, characterised in that considered in a plane parallel to the upper surface, the cross-section of the recesses increases in a direction towards the upper surface. In that way in a bond of such blocks, when the recesses are filled with grit, the blocks can be retained in their place in a relatively reliable and secure manner. Furthermore the upward increase in vertical direction of the cross-section of the recess ensures a reduction of the pressure and speed of water that might move upwards from below the blocks.

Preferably, each time considered in a plane parallel to the upper surface, at least over a first portion of the recess, the cross-section of the recesses gradually increases in a direction towards the upper surface, wherein, considered in a vertical plane of cross-section, preferably a vertical plane of cross-section containing the centre of gravity of the block, particularly a plane of symmetry of the recess, the wall of the recess has a gradient of over 1 %, preferably approximately 2 to 4% with respect to a centre line through the centre of gravity and perpendicular to the lower surface.

In other words, the cross-section of the recesses, considered in a plane parallel to the upper surface, at least over a first portion of the recesses, gradually increases in a direction towards the upper surface, preferably with a gradient of over 1%, preferably approximately 2 to 4%.

The circumferential surface, particularly in case of concrete blocks, will have a slight tapering in upward direction, particularly of approximately 0.5%, required for release from a mould/shuttering. The gradient in the recess according to the invention exceeds the gradient of the slight tapering that is already present. If according to a further development of the invention, the recesses start at a distance from the lower surface, in the lower half of the circumferential surface of the block, over a large length, thus rather a lot of grit can be accommodated and therewith the vertical engagement length will be increased.

In a particularisation the recess is bounded in a direction towards the lower surface by a step that is situated in the lower half of the circumferential surface of the block, as a result of which the forces exerted on the grit by upwardly moving water are effectively reduced.

Alternatively in downward direction the recess can smoothly merge into the circumferential surface, or via a buckle. In a further development, in which retaining the grit in its place is further enhanced, the recesses are bounded in two opposing circumferential directions of the circumferential surface by confining edge areas, which preferably, considered in circumferential direction have a mutual distance of 6cm at the most, preferably 3cm at the most, more preferably 1.5cm at the most, wherein, preferably below and/or in and/or directly contiguously to, considered in a direction away from the recess, the confining edge areas, the circumferential surface forms a contact surface for contact with another block according to this claim in a condition placed in a covering. The confining edge areas extend substantially parallel to each other. It is noted that substantially parallel is also deemed applicable in case of said slight tapering required for the release from a mould/shuttering.

In a particularisation the largest dimension of the recess in a horizontal direction transverse to the circumferential surface at that location is smaller than 3cm, preferably smaller than 1cm, more preferably smaller than 0.5cm. In an embodiment of the block with one or more side surfaces, that in between them define corner areas, the recesses are arranged in at least one of the corner areas. In that way the blocks can be secured to each other in the corner areas via the grit. Alternatively and/or in addition the recesses can be arranged in at least one of the side surfaces.

Preferably the block has a centre line that is perpendicular to the lower surface and contains the centre of gravity of the block, wherein the recess in planes of cross-section perpendicular to the centre line, measured along a line, particularly a line of symmetry, passing through the recess and through the intersection of the centre line with the plane of cross-section in question, has a depth, which depth increases as regards planes of cross- section that are consecutive in upward direction, particularly gradually, particularly over the full vertical height of the recess.

Particularly when the circumferential surface comprises a number of side surfaces that in between them define corner areas, and the recesses are arranged in at least one of the corner areas, wherein the recess comprises a bottom that extends in upward direction, said bottom advantageously is at an angle to a vertical line through the centre of gravity of the block (perpendicular to the lower surface of the block) that is larger, preferably a number of times larger than the angle of an edge line of the confining edge areas which edge line is situated in a vertical plane with the vertical line, which edge line is farthest from said vertical line, with said vertical line. The edge lines may assume the said gradient required for release.

In one embodiment, in a horizontal cross-section of the block, the circumferential surface defines a polygon. In that case the block can be substantially formed according to a first, preferably regular prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the prism base, wherein the block comprises a lower surface, an upper surface and a circumferential surface having a circumferential series of side surfaces that in between them define corner areas, which extend substantially parallel to the prism centre line, wherein the recesses extend substantially parallel to the prism centre line, wherein, preferably at least one of the side surfaces contacts the perimeter surface between the corner areas, considered at a location in circumferential direction. It is noted that substantially parallel is also deemed applicable in case of said slight tapering required for the release from a mould/shuttering.

In that case the block in the corner areas, particularly in a lower part of the circumferential surface, may form contact surfaces for abutment against adjacent blocks in the bond, wherein the contact surfaces are situated on the perimeter surface of the prism, wherein at least some, preferably each, of the corner areas are provided with a said recess. In that case the recess may intersect the axial plane containing the prism centre line and the prism corner line parallel thereto situated near the corner area in question.

According to a further aspect the invention provides an assembly of a number of blocks according to the invention, wherein of two or more blocks the said recesses form a joint accommodation space for grit, wherein the accommodation space preferably is funnel-shaped and preferably is bounded in downward direction by steps in the circumferential surfaces of the blocks in question.

According to a further aspect the invention provides a block, particularly of concrete, for with a number of identical blocks forming a bond for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, wherein the block is substantially formed according to a first, preferably regular prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the prism base, wherein the block comprises a lower surface, an upper surface and a circumferential surface having a circumferential series of side surfaces that in between them define corner areas that extend substantially parallel to the prism centre line, wherein the block in the corner areas forms contact surfaces for abutment against adjacent blocks in the bond, wherein the contact surfaces are situated on the perimeter surface of the prism, characterised in that at least some, preferably all, of the corner areas are provided with a recess, which recess extends substantially parallel to the prism centre line from a starting location in the lower half of the block that is spaced apart from the lower surface to at least near the upper surface, preferably up into the upper surface, preferably at the location of a highest surface of the upper surface, wherein, considered at a location in circumferential direction, preferably at least one of the side surfaces contacts the perimeter surface between the corner areas preferably at least in a lower part of the block.

"At least near the upper surface" here means that the recess ends at the top at a distance to the upper surface of approximately 0% of the height of the block at the most. In the stage of use, incorporated in a covering in a bond with identical blocks the grit washed in in the said recess(es) will as a result be retained in the corner area more reliably against the forces of water flowing over the covering and water exiting upwards. As a result at those corner areas the blocks will more reliably be secured to the adjacent blocks, as a result of which the stability of the covering is increased. Furthermore a mutual, relative tilting of meeting blocks in planes that are perpendicular to the prism base can be counteracted sooner. The prism centre line may coincide with the said centre line through the centre of gravity of the block.

If the recess intersects the axial plane containing the prism centre line of the straight prism and the regular prism corner line parallel thereto situated near the corner area in question, the recesses of blocks sitting against each other in the covering in the corner areas, will together form one at least almost blind hole filled with washed in grit. The grit is even more reliably retained there in the recesses in the corner areas, if in two opposing circumferential directions of the circumferential plane the recess is bounded by confining edge areas. If the confining edge areas extend substantially parallel to the prism centre line the mutual contact between the blocks is increased, particularly in height direction, and the stability enhanced. It is noted that substantially parallel is also deemed applicable in case of said slight tapering required for the release from a mould/shuttering.

Upward force, exerted on the grit by water flowing out upwardly, is kept limited if the recess comprises a bottom surface facing away from the prism centre line, which bottom surface with respect to the prism centre line has a tapering of over 1 %, preferably 2 to 4%, and of which the normal has an upward directional component, as a result of which the surface of the recess(es) in a plane of cross-section transverse to the prism centre line is increased in upward direction and the rate of flow decreases. The circumferential surface will in particular in case of concrete blocks have a slight tapering in upward direction of particularly approximately 0.5%, required for release from a mould/shuttering. The gradient in the recess according to the invention is considerably larger than the gradient of said tapering. The interlocking between grit and the corner areas of the blocks is enhanced if the recess comprises a bottom surface facing away from the prism centre line, which bottom surface is provided with an elevation preferably extending substantially parallel to the prism centre line, which elevation is receded with respect to the prism corner line of the corner area in question.

If the starting location of the recess is located in the lower quarter of the height of the block a relatively high confined column of grit can be realised in the corner areas .

According to a further aspect the invention provides a block, particularly of concrete, for with a number of identical blocks forming a bond for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, wherein the block is substantially formed according to a first, preferably regular prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the prism base, wherein the block comprises a circumferential surface having a circumferential series of side surfaces that in between them define corner areas that extend substantially parallel to the prism centre line, wherein the block in the corner areas forms contact surfaces for abutment against adjacent blocks in the bond, wherein the contact surfaces are situated on the perimeter surface of the prism, wherein the side surfaces are present in an even number, wherein first side surfaces are each time situated between second side surfaces, wherein the first side surfaces and the second side surfaces are shaped different from each other, wherein the first side surfaces are provided with a with respect to the notional perimeter surface of the prism receded main recess that is continuous in the direction parallel to the prism centre line, which main recess forms a recess having the largest cross-section of all recesses in the block and forms a channel having a bottom, which bottom is provided with an elevation that is situated at least near the upper surface. The main recesses serve to form relatively large passages for water that are regularly distributed over the covering, which water could otherwise build up an undesirably high pressure under the blocks. By means of the invention it is achieved that the main recess in the said plane of cross-section may have a large surface without the according to standards allowable largest circular passage, in the Netherlands 5cm, being achieved or exceeded, when the blocks that sit against each other move away from each other, which for instance may be the case when the basis locally allows for slight tilting in the vertical plane.

Preferably the elevation extends over at least substantially the full length of the main recess.

An as regards plane of cross-section contiguous, relatively large surface is preserved if the elevation has an apex that is receded with respect to the perimeter surface in question of the prism. The elevation may have a convex surface, considered in the plane of cross- section. Considered in said plane of cross-section, the elevation can be situated symmetrical with respect to an axial plane containing the prism centre line and perpendicular to the perimeter surface in question of the prism, as a result of which the overall surface may be large. Preferably the elevation extends substantially parallel to the prism centre line.

For obtaining an as large as possible surface in the plane of cross-section the main recess in that plane may be substantially concave, particularly according to a circular curve. The elevation has its origin preferably near the deepest point of the main recess, considered in the plane of cross-section.

In other words the main recess can be substantially W-shaped, considered in said plane of cross-section.

In one embodiment with large main recesses the main recess at the edges merges into the corner areas.

In one embodiment the second side surfaces are flat. In another embodiment the second side surfaces are provided with a with respect to the main recess shallow auxiliary recess, which is flat considered in a plane of cross-section that is transverse to the prism centre line. In view of a placement in the covering, in which the auxiliary recess of the one block sits opposite the main recess of an adjacent block, the function of the elevation in the main recess in preventing too large a largest size can be supplemented by a rib provided in the second side surfaces and dividing the auxiliary recess. The rib as well can advantageously, considered in said plane of cross-section, be symmetrical with respect to an axial plane containing the prism centre line and perpendicular to the perimeter surface in question of the prism.

The rib may extend up into the perimeter surface in question of the prism.

In the above-mentioned block according to European patent application 1.275.784 the upper surface comprises a descending edge surface on each side of the hexagonal central plane, which edge surface in outward direction connects to its own corner area. The gradient of the edge surfaces is for instance 70 degrees to the prism centre line. In the covering the descending surfaces form target surfaces for the water in a wave run-up as a result of which the energy dissipation is increased.

For storage and transport the blocks are packed in groups of for instance 16 pieces in a firm shrinking film or strap. Due to the descending edge surfaces of the upper surfaces of the blocks, the blocks in a superimposed group of blocks may tilt with respect to the blocks on which they support. As a result mutual shifting may take place or a whole stack may topple down. In order to prevent this, each pair of groups is placed on a pallet. The pallets themselves, however, take up storage space and need to be returned from the work.

According to a further aspect the invention provides for an improvement thereof with a block, particularly of concrete, for with a number of identical blocks forming a bond for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, wherein the block is substantially formed according to a first, preferably regular, preferably hexagonal, prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the prism base, wherein the block comprises a lower surface, an upper surface and a circumferential surface having a circumferential series of side surfaces that in between them define corner areas that extend substantially parallel to the prism centre line, wherein the block in the corner areas forms contact surfaces for abutment against adjacent blocks in the bond, wherein the contact surfaces are situated on the perimeter surface of the prism, wherein the upper surface comprises a central plane that is parallel to the lower surface, wherein the upper surface comprises first side edge portions and second side edge portions, that are adjacent to the circumferential surface of the block, wherein the first side edge portions bound the central plane and the second side edge portions via edge surfaces that outwardly descend from the central plane are connected to the central plane. In that way the surface on which the blocks of a group of blocks sitting on top support on the blocks of an underlying group of blocks is increased, while preserving an energy dissipating action as a result of the (still) present descending edge surfaces, or even an increase of said action if second side edge portions in a laid bond with identical blocks connect to first side edge portions of an adjacent block.

The first side edge portions may in that case be situated between second side edge portions, so that an alternating positioning is achieved.

In one embodiment -considered in top view- the upper edges of the corner areas coincide with one of the first and second side edge portions. This is particularly advantageous in the said embodiment according to the invention in which the corner areas are provided with recesses that at least substantially extend up to the upper surface, which recesses after all will then be upwardly extended at the first side edge portions and as a result are able to contain/confine more grit.

The first and second side edge portions preferably are present in a number that equals the number of side surfaces. In one embodiment the first and second side edge portions in circumferential sense are offset with respect to the side surfaces, preferably at 30 degrees. Accommodating the blocks in the covering and making the covering is enhanced if the base and the upper surface of the prism form a polygon having an even number of sides, preferably form a (regular) hexagon. The block according to the invention needs to be distinguished from a tile, as among others shown in FR 2.252.451 and that is additionally intended to provide a vegetation growth facility. The block according to the invention is shaped rather like a column and has sides whose length is in the order of magnitude of the height of the block at the most. For instance the sides in a block having a hexagonal prism could be over 16cm and the height 15cm, 20cm, 35cm to for instance 50cm. In most cases the height of the block will be larger than its largest transverse dimension.

According to further aspect the invention provides an assembly of a number of blocks according to the invention placed in a honeycomb bond, wherein the blocks are placed together with their corner areas and abut each other with the contact surfaces. In that case blocks can be used that are provided with said main recess with elevation, wherein each time a first side surface of a block is situated opposite a second side surface of an adjacent block.

Such assemblies can be used in the fields of a covering. Each assembly, a standard assembly, may for instance comprise 16 identical blocks having a hexagonal prism, in four series, mutually situated offset over half a block size. The end or transverse edges are then formed by side surfaces of the blocks, almost castellation-shaped. Both longitudinal edges are sig-zag- shaped, with each time two consecutive side surfaces of each block.

Alternatively such an assembly may comprise 14 whole blocks, in four series mutually situated offset over half a block size, wherein at the end or transverse edges four half blocks are incorporated in order to make them somewhat straight. Said half blocks can then have a quadrangular cross- section, wherein three consecutive sides correspond with three consecutive sides of one of the whole blocks and the fourth side is situated in the end or transverse edge.

In case the slope to be covered - considered in a horizontal plane - extends according to a curve, convex or concave, series of groups situated higher need to cover a smaller or larger length, respectively, than the groups situated lower. Due to interlocking at the location of the zig-zag- shaped longitudinal edges that is difficult to realise. It is an object of the invention to provide a solution for this.

According to a further aspect the invention for that purpose provides an assembly of blocks placed in a bond for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, wherein the majority of the blocks is formed as a first type of block, particularly a block according to the invention, which substantially forms a first, substantially regular hexagonal prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the base, wherein each first block comprises a circumferential surface having a contiguous series of side surfaces, wherein the blocks are placed against each other in a honeycomb bond with two or more parallel series of blocks, wherein the blocks in each series are placed against each other with side surfaces that transversely face the series direction, wherein the blocks in the even series are offset in series direction with respect to the adjacent blocks in the odd series over a distance corresponding with 0.5 3 x the side (a) of the first prism so that a zig-zag-shaped transition line is formed between adjacent series, wherein the first prism centre lines of the first blocks in each series are situated on a related first series line, wherein the consecutive series lines are at a bond distance from each other of 1.5 x the side of the first prism, wherein at at least one longitudinal side a series of second blocks is included in the honeycomb bond, which second blocks deviate from the first blocks and each form substantially a second prism and fit against the adjacent series of first blocks in order to form a same zig- zag-shaped transition line therewith, wherein the second blocks at the side facing away from the adjacent series of first blocks form a substantially stretched longitudinal side, wherein the second prisms have second prism centre lines that are situated on a related second series line, which is situated at the bond distance from the first series line of the adjacent series of first blocks, wherein the distance between the stretched longitudinal side and the second series line is half the bond distance.

In that way it is possible to place two of such assemblies with their stretched longitudinal sides against each other and have their opposing longitudinal sides interlock with the standard assemblies having zig-zag- shaped edge or, if the other longitudinal edge is designed stretched in a similar way with second blocks, placed against a further assembly at said longitudinal edge as well. The blocks on both stretched sides can be placed in any position with respect to each other. In that way it is possible at the entrance to the curved trajectories to replace the standard assemblies by one or more assemblies according to the invention with a stretched longitudinal side, for in that way realising a number of tracks of parallel series of such deviating assemblies, optionally with one or more standard assemblies in between them. Each track may follow its own pattern, independent from the adjacent track. At the exit of the curved trajectory one can change to only standard assemblies again.

It is noted that it is known per se from the Rona®ton+ program that in order to achieve a snug connection at the lower longitudinal edge and at the upper longitudinal edge of the covering built up from blocks, two deviating assemblies or groups are provided, in the case of 16 blocks having four deviating blocks at one longitudinal edge. The deviation consists in that there is no longer question of a zig-zag shape but of a substantially stretched side, obtained as the deviating blocks are pentagonal, wherein the part that otherwise forms two side surfaces is chamfered. The length of the other side surfaces has then remained the same. The width of said deviating groups deviates to such an extent from that of the standard assemblies that an acceptable transition between curved trajectory with the deviating groups and a stretched trajectory with standard assemblies is not possible. Preferably the side surfaces of the second blocks, at least as regards the side surfaces forming the zig-zag-shaped transition line with the adjacent series of first blocks, as regards length correspond with the side surfaces of the first blocks, so that between the first and the second blocks the same functions can be fulfilled as between the first blocks one to the other.

Just like in the special Rona®ton+ groups the second blocks may have a pentagonal base.

At least as regards their half situated between the second series line and the adjacent first series line, the second blocks preferably are identical to the first blocks.

In one embodiment, the second blocks are provided with two side surfaces that are situated transverse to the series line and oriented opposingly, which side surfaces have a larger length than the correspondingly oriented side surfaces of the first blocks and have a profile corresponding therewith.

For preventing the second blocks from unwanted shifting, the side surfaces of the second blocks situated in the stretched longitudinal sides may be provided with a number of recesses that in longitudinal direction are situated at an intermediate distance from each other, wherein the recesses comprise first and second recesses that differ in length. In one embodiment at least one first recess is either situated between two second recesses or at least one second recess is situated between two first recesses. In that case two types of second blocks can be distinguished: the one with more first recesses and the second with more second recesses. Preferably the intermediate distance between a first and a second, adjacent recess is smaller than the length of at least one of those recesses.

The first recess may have a length that corresponds with the length of the intermediate distance plus the length of the second recess. In that way the chances are increased that in case of two stretched longitudinal sides of assemblies according to the invention being placed against each other, recesses in both longitudinal sides come to lie opposite each other and thus form an enlarged space in transverse direction, that is more accessible to washed in grit.

These chances are increased if the length of the first recess is larger than the length of the second recess, preferably twice as large and/or if on either side of the second recess a first recess is situated. The first and second recesses as a group preferably are situated symmetrically with respect to the centre of the side surface of the second block.

Cooperation with recesses in the corner areas of other blocks can be enhanced if one of the recesses is situated at a distance to the nearest corner of the second block corresponding with the intermediate distance.

Retaining washed in grit in the recesses is enhanced if the first and second recesses extend substantially parallel to the prism centre line substantially from a starting location in the lower half of the block situated at a distance from the lower surface to at least near the upper surface. This can also be advantageous for the connection to the lower portions of the corner areas of the opposite blocks.

According to a further aspect the invention provides a block apparently intended and suitable as second block for an assembly according to the invention. According to a further aspect the invention provides a block apparently intended and suitable as first block for an assembly according to the invention. In accordance with the above the invention also provides a covering of a bank, coast or dike, including spillways, for protection against wave attacks and water flows, comprising a set of first assemblies of first blocks that each have substantially been formed according to a first substantially regular hexagonal prism having a first prism perimeter surface and a first prism centre line oriented perpendicular to the prism base, wherein each first block comprises a circumferential surface having a contiguous series of side surfaces, wherein the first blocks have been placed against each other in a honeycomb bond having two or more parallel series of blocks, wherein the first blocks in each series are placed against each other with side surfaces that transversely face the series direction, wherein the first blocks in the even series are offset in series direction with respect to the adjacent first blocks in the odd series over a distance corresponding with 0.5 3 x the side of the hexagon of the first prism so that a zig-zag-shaped transition line is formed between adjacent series, wherein the first prism centre lines of the first blocks in each series are situated on a related first series line, wherein the consecutive series lines are situated at a bond distance from each other of 1.5 x the side of the hexagon of the first prism, wherein the first assemblies are placed according to one or more mutually parallel series of first assemblies, which series preferably extend substantially in horizontal main direction along a slope, wherein preferably one series of the first assemblies of deviating assemblies according to the invention form a continuation of a series of first assemblies in series direction.

In one embodiment of the pair of deviating assemblies the stretched longitudinal sides are placed together, according to a divisional surface, and for each block at its stretched longitudinal side at least two grit accommodation spaces that cross the divisional surface are formed, particularly by two cooperating recesses formed in the opposite side surfaces of the blocks at the stretched longitudinal sides.

In that case the blocks can be provided with rounded corner areas at the longitudinal ends of the side surfaces situated at the divisional surface, wherein the rounded corner areas form a grit accommodation space with a corner area of an adjacent identical block and a recess in the side surface of an opposite block. In a covering according to the invention the one assembly according to the invention can be designed with a consecutive series of first, second and first recesses in the stretched longitudinal side and the other assembly according to the invention can be designed with a consecutive series of second, first and second recesses in the stretched longitudinal side.

At least one pair of said deviating assemblies can form a continuation of a series of first assemblies. Of the pair of deviating assemblies the stretched longitudinal sides can be placed together. The series of deviating assemblies can particularly be used to follow a curved trajectory of the covering.

According to a further aspect the invention provides a covering of a bank, coast or dike, including spillways, for protection against wave attacks and water flows, comprising a number of said deviating assemblies according to the invention, which are placed in two mutually parallel series of those assemblies that are contiguous to each other and preferably extend in substantially horizontal main direction along a slope, wherein the assemblies in the first series with their stretched longitudinal side abut the stretched longitudinal side of the second series.

According to a further aspect the invention provides a block for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, which block at least approximately forms a prism having a prism perimeter surface, wherein the block comprises an upper surface, a lower surface and a circumferential surface having a contiguous series of side surfaces, wherein a first and a second side surface adjacent thereto extend according to a first and a second side of the perimeter surface, which sides have a mutually equal length (a) and are at an angle of 120 degrees to each other, wherein a third side surface and a fourth side surface respectively extend according to a third and a fourth side of the perimeter surface, that are contiguous to the first and second side surface, at angles of 120 degrees, and wherein a fifth side surface extends according to a fifth side of the perimeter surface that is contiguous to both the third and the fourth side surface, at angles of 90 degrees, wherein the third and fourth sides have a length of approximately 1.25(a). Such a block can be used as said second block in an assembly according to the invention, with comparable advantages.

Preferably said block has a plane of cross-section that is substantially parallel to the fifth side and intersects the third and fourth sides of the perimeter surface at a distance of 0.5(a) of the intersections of the first and third sides and second and fourth sides, respectively, and wherein the distance from the fifth side to said plane of cross-section is approximately 0.75(a). The part of the prism that is situated at the side of the plane of cross- section facing away from the fifth side surface can approximately form a half of a regular hexagonal prism, so that an optimal fit with other first and/or second blocks can be realised. For that purpose the block as regards the half of the regular hexagonal prism can be formed in accordance with the block described in claims 12-44 in an approximately regular hexagonal design. In an application of said block it can be used in an assembly of blocks comprising two series of such blocks, wherein the blocks in the first series and the blocks in the second series with their fifth side surfaces are situated parallel and with their first and second side surfaces define a zig-zag- shaped transition line between the two series of blocks.

In an alternative application of this block it can be used in an assembly of blocks comprising two series of such blocks, wherein the blocks in the first series and the blocks in the second series with their fifth side surfaces are situated parallel, wherein between both series of blocks one or more series of other blocks are situated that are parallel thereto and that have a substantially regular hexagonal prism shape, while forming a honeycomb bond with each other and with the blocks in both of said series. The other blocks can then for instance be shaped like blocks according to any one of the claims 12-44.

In a further alternative application of said pentagonal block it can be used in an assembly of blocks comprising one first series of such blocks, wherein the blocks in the first series with their fifth side surfaces are situated parallel to the series direction, wherein adjacent and contiguous to the first series one or more series of other blocks are situated that are parallel thereto and have a substantially regular hexagonal prism shape, while forming a honeycomb bond with each other and with the blocks in the first series. The other blocks can then for instance be shaped like blocks according to any one of the claims 12-44.

In these three cases, at end or transverse edges the assembly can also have been made stretched by fitting blocks, particularly quadrangular fitting blocks. These can be situated at a stretched longitudinal edge, in which case two consecutive side surfaces of the fitting blocks that are situated against blocks at the longitudinal edge, correspond with the said first and second side surfaces. In case of a series of said substantially hexagonal prism-shaped blocks being present, the fitting blocks can be incorporated at the ends of said series in an embodiment having three consecutive side surfaces that correspond with either said first, second, first or second, first, second side surfaces. It is known for covering a slope and the like to provide a group of concrete blocks that have beforehand been attached to a mat that may serve as filter mat for the granular material of the basis of the covering. An example is Betomat (registered trademark) in which concrete blocks have been attached to a geotextile using synthetic pins. The geotextile allows water to pass through in a direction perpendicular thereto. Another example is Bevemat (registered trademark), with a mat that allows water to pass through in three dimensions, therefore also allows flow in the mat itself. The mat is provided with loops for accommodation in the concrete of the blocks. During the manufacturing the mat has to be part of the mould of the blocks. As a consequence the distance of the blocks during moulding equals the distance of the blocks in the work, which may be disadvantageous for the stability and for the permeability of the covering.

According to a further aspect the invention provides an improvement in this respect by a covering assembly for covering a bank, coast or dike, including spillways, for protection against wave attacks and water flows, comprising a number of blocks placed in a bond, the blocks having an upper surface and a lower surface, wherein at least a number of the blocks with their lower surfaces are adhered to a filter mat that is provided with passages in a direction perpendicular to the plane of the mat and with passages in the plane of the mat, particularly in random directions therein. The connection between the blocks and the filter mat need not take place through the accommodation of mat portions in the moulding material of the blocks, such as concrete, as a result of which the position of the blocks during moulding can be different than after connection to the mat. In that case the blocks are able to define a more closed surface, at least with more discrete vertical passages instead of a contiguous net of slit-shaped passages. The mat itself, which preferably has an open structure in three dimensions, provides a quick connection with the discrete vertical passages. The permeability in the three dimensions in the mat preferably is substantially the same. A useful example of such a mat is a mat by Enkamat (registered trademark). The adhesion can be realised by means of an added adhesive, such as glue.

According to a further aspect the invention provides a covering with covering assemblies according to the invention, wherein the blocks form a standard assembly or a deviating assembly according to inventions discussed above. The mat keeps the blocks together.

The covering assembly preferably is substantially rectangular, wherein the mat at at least one cathetus, preferably at two adjacent catheti, projects from the blocks, so that in the work a proper filter closure is realised.

According to a further aspect the invention provides a method for manufacturing a covering assembly according to the invention, wherein the blocks are manufactured in a mould from hardenable moulding material, which for instance hardens under the influence of increased temperature or that bonds hydraulically, such as concrete, after sufficient hardening are brought as a group into a bond of abutment and are placed against the mat or the mat is placed against the group of blocks, wherein the mat is attached to the blocks by adhesion.

According to a further aspect the invention provides a covering of a bank, coast or dike, including spillways, for protection against wave attacks and water flows, comprising a number of blocks placed in a bond, which in between them form slits or other kinds of openings for accommodation of a grain material, such as grit, wherein the grain material is obtained from ultra basic deep rock that contains Mg-containing olivine, particularly from peridotite, particularly from dunite. The content of Mg in the olivine preferably is over 50%. The content of Mg preferably is as high as possible, preferably over 70%, wherein the deep rock preferably is forsterite. An advantage thereof is that the Mg-containing olivine bonds C02 up to 5/4 times its own weight. Use in slopes bounding water bodies such as a lake, sea or channel is advantageous because salt optionally present in said water increases the reaction rate. The grit then has and additional function in the covering, which it retains for a long time should it inadvertently be flushed out of the covering.

The granular material preferably is rather coarse and comprises grains having a sieve size larger than 10mm and smaller than or equal to 32mm.

The effectiveness and ease of installation is increased if the slits and openings formed between the blocks are only filled with the said grain material.

The blocks can be formed as described above.

According to a further aspect the invention provides for the use of granular material obtained from ultra basic deep rock containing Mg-containing olivine, particularly from peridotite, particularly from dunite, in a covering of a boundary of a water body, such as a channel, river, lake and the like for binding C02 and/or removing heavy metals. The granular material used may have the specifications as mentioned above. The aspects and measures described in this description and the claims of the application and/or shown in the drawings of this application, may where possible also be used individually. Said individual aspects and other aspects may be the subject of divisional patent applications relating thereto. This particularly applies to the measures and aspects that are described per se in the sub claims.

SHORT DESRIPTION OF THE DRAWINGS The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings in which:

Figures 1A-C show an oblique top view, a top view and a side view, respectively, of an exemplary embodiment of a block according to the invention;

Figures 2A-D show a cross-section and details B-D, respectively, of the block of figures 1A-C;

Figures 3A-C show a perspective view of a standard assembly or group with blocks according to figures 1A-C, a top view thereof and a detail of a meeting location of three blocks in said assembly, respectively; Figures 4A-C show an oblique top view, a top view and a side view, respectively, of a first exemplary embodiment of a deviating block according to the invention;

Figures 5A-C show an oblique top view, a top view and a side view, respectively, of a second exemplary embodiment of a deviating block according to the invention;

Figure 6A shows a first deviating assembly of blocks according to figures 1A-C with blocks according to figures 4A-C at one edge;

Figure 6B shows a second deviating assembly of blocks according to figures 1A-C with blocks according to figures 5A-C at one edge;

Figures 7A and 7B show an oblique top view and a top view, respectively, of a first combination of assemblies of the figures 3A-C, 6A and 6B; Figures 8A-C show an oblique top view, a top view of a second combination of assemblies of figures 3A-C, 6A and 6B and a detail of a meeting location of three blocks in said combination, respectively; Figure 9 shows a schematic view of a slope covered with assemblies of blocks according to the invention in accordance with figures 8A and 8B;

Figures 10A-E, respectively, show a top view of a half of a package of blocks of figures 1A-C, after diseasing the mould, a top view of joining said blocks, a top view of the package or assembly of figures 3A-C including mat, a cross-section and a sectional plane of a covering on a slope with such assemblies;

Figures 11A-C show an oblique top view, a top view and a cross-section, respectively, of another exemplary embodiment of a block according to the invention;

Figure 12 shows a side view of a pack having a number of packages of blocks according to figures 1 A-C; and

Figures 13A and 13B show a top view and an oblique top view, respectively, of another embodiment of an assembly of blocks according to the invention. DETAILED DESCTRIPTION OF THE DRAWINGS

The block 1 shown in the figures 1A-C is manufactured by moulding a hardenable moulding material, in this example hardenable moulding material that bonds hydraulically, such as concrete and apart from some local recesses and a slight tapering (less than 1 % for instance 0.5%) for releasing from a mould/shuttering, substantially has the shape of a notional, straight regular hexagonal prism P, of which the perimeter surface M comprises six perimeter side surfaces Z, which perimeter surface M at the bottom ends up in a prism base and at the top in an upper surface parallel thereto, each formed by a regular hexagon wherein the length of the perimeter side surfaces Z is (a). The notional prism P has a prism centre line S, that also forms the centre line of the block 1. The block 1 has an upper surface 2 and a lower surface 3 that are respectively substantially situated in the planes O and B of the prism P, perpendicular to the centre line S. The upper surface 2 comprises a regular hexagonal surface or central plane 4, which at the sides 5 merges into flat outwardly sloping planes 6a, b that belong to the upper surface and are at an angle of for instance 70 degrees to a plane of cross-section perpendicular to the centre line S.

In accordance with the main shape of the prism P, the block 1 has six side surfaces, divided into three first side surfaces 7 and three second side surfaces 8, that are alternately arranged. The first and second side surfaces 7,8 meet each other in corner areas 9 that are rounded slightly convex, considered in a plane perpendicular to the centre line S. The corner areas 9 have a lower part 10 that defines the outer circumference of the block, considered in cross-section perpendicular to the centre line S. The lower part 10 extends from the lower surface 3 over a height of less than ¼ of the distance between the lower surface 3 and the upper side of upper surface 4 of the block 1. In the corner area 9, via a step 13, the lower part 10 merges into a recess 1 that extends from there up into the upper surface 2. The recess 11 , that is symmetrical with respect to a radial plane R1 containing the centre line S, has a bottom 15 that extends in substantially vertical direction and to either horizontal side is bounded by confining edges 14. The lower part 10 forms contact surfaces 12 of the corner areas, which considered from above are situated on either side of the recess 11. As a result of the said slight tapering required for the moulding process, the surfaces that are situated higher and adjacent to the confining edges will not touch each other, in a perfect mutual parallel position of the centre lines S of the blocks 1. In the middle the bottom 15 is provided with an elevation 16 extending over the height of the recess 11 and receded with respect to the contour of the corner area 9, as can be seen in figure 2B. Although not shown in figure 2B the bottom 15 in upward direction converges slantingly inwards, such as in plane M1 , towards centre line S with an angle to the centre line S of 3 degrees or more, so a number of times more than the incline required for a proper release from the mould during manufacturing of the block 1. The bottom 15 therefore runs upwards at a larger gradient than the confining edges 14, in their outermost edge line indicated with S14. The corner area 9 shown is symmetrical with respect to a middle surface M1 containing the centre line S.

The first side surfaces 7 are formed with a relatively deep recess 20 that is vertically through-going between upper surface 2 and lower surface 3 and that is symmetrical with respect to a radial plane R2 containing the centre line S. The recess 20 is defined by a surface 21 which, counted from the adjacent corner area 9 and considered in said plane of cross-section, comprises a convex section 21a and a concave section 21 b. The concave sections 21b are situated on a circle of .which the diameter at least substantially coincides with the perimeter surface M at the side in question. For in the middle limiting the depth of the recess 20 both sections 21b do not merge into each other according to their curve, but between both of them another convex section 21c is provided, forming an elevation 22 in the recess 20, which however is receded with respect to the related perimeter side surface Z, as a result of which the largest distance of surface 21 to the perimeter side surface Z is limited. In particular the largest distance between the circular surface 21b and perimeter side surface Z is reduced from -in this example- the radius of said circle to approximately the half of it. Nonetheless the remaining sections 20a-c form one unity with a sufficient flow-through surface. The recess 20 here acquires the look of a W-shaped space. The recess 20 is symmetrical with respect to a middle surface M2 containing the centre line S.

The second side surfaces 8 are provided with a shallow, flat recess 25 extending between edges 27 that form the transition to the two corner areas 9 bounding said side surface 8, and which recess in the middle is provided with convex rib 26 extending over the height of the block 1 , which rib is symmetrical with respect to the a radial plane R3 containing the centre line S. The rib 26 extends up into the perimeter side surface Z at that location, wherein the recess is divided into two halves 25a, b. The recess 25 is symmetrical with respect to a middle surface M3 containing the centre line S.

The blocks 1 may have a length (a) of perimeter surface Z of approximately 16-17cm and a height of 35cm. The steps 3 may be situated at 8cm from the lower surface. The distance of the surface 21b to the perimeter surface Z may at the top be 1.5cm, the height of the rib 26 at the top may be ½cm, and the depth of the recess 11 at the top 1cm. The blocks 1 can be made several at a time in a mould, during pouring the concrete and hardening being separated from each other by thin mould walls. When the blocks 1 have hardened sufficiently the mould walls are pulled up and the blocks 1 are brought against each other by a machine in order to form one group or assembly 100, see figure 3A, that can be picked up. Such a group of 16 blocks 1 may have a largest length of 1.3m, a largest width of 1.08m. The four series of blocks 1 can then have a length of 1.16m. The blocks 1 form a honeycomb bond, wherein the prisms of the blocks 1 define the pattern. In series direction the blocks 1 are situated with their first and second side surfaces 7, 8 against each other and in the one series are offset with half a block size with respect to the blocks 1 in an adjacent series. Said block size (also see figure 1 B) is (a) 3, in which (a) is the length of a perimeter side surface Z. The block size in a direction transverse thereto is 2(a), as a result of which the transverse distance between the centre lines S of blocks 1 in adjacent series is 1.5(a).

In the assembly 100 the blocks 1 are situated against each other with the corner areas, with the contact surfaces 12 that are situated at that location (figure 3C). Three blocks 1 meeting each other with the corner areas 9 form narrow funnels 102 in the corners of the pattern, which funnels after placement can be washed in with fine grit. The funnels 102 have a relatively long (in upward direction) portion defined by the recesses 11 , which at a lower end thereof via the steps 13 merge into a narrow passage bounded by the lower portions 10 of the corner areas, which passage is for vertically moving water. The vertical edges 14 of the recesses 1 prevent that grit is able to escape laterally from the recesses 11 and from the funnels 102. During wave load tests it appeared that a covering with blocks substantially according to blocks 1 provides a very high stability. The grit in the corner areas with three recesses of the three blocks meeting each other, substantially remained in place and thus could continue to contribute to the preservation of the integrity of the covering.

Between the sides of the blocks the side surfaces 7 and 8 together with their recesses 20 and 25 form one large passage 101 , for water escaping upward (direction B) from the slope. These passages 101 are also washed in with grit, coarser than the grit for the funnels 102. The elevation 22 and rib 26 prevent that a notional ball having a cross-section of 5cm may end up in the passage 101 , preserving sufficient flow-through surface.

The longitudinal edges of the assemblies 100 are zig-zag-shaped. As a result they can be placed next to each other in an interlocking manner, wherein the series direction extends in horizontal direction along the slope. In case it is desirable to provide a more stretched longitudinal edge to a group of blocks, use can be made of the deviating blocks 1a and 1b of figures 4A-C and 5A-C.

The block 1a of figures 4A-C as regards the portion situated below the line T considered in the drawing in figure 4B, corresponds with the blocks 1 and therefore has a pair of first and second sides 7, 8 that connect to each other. The centre line Sa is related to that portion of block 1a that is identical to block 1 and as a consequence is situated at the same position as centre line S, for that portion. The adjacent sides 7a, 8a are extended until the distance from the fifth side 78a to a parallel line through the plane containing the centre line Sa is ¾ (a). The length of the sides 7a, 8a at least of the related prism surfaces, then is 1.25(a). The length of the side 78a also corresponds with the distance between two opposingly situated sides 7,8 of block 1 , and therefore is (a) 3.

The fifth side 78a is stretched and formed symmetrically with respect to a middle surface M4 containing the centre line Sa. The side 78a is provided with a number of shallow recesses 80 and 81 , wherein the recess 80 is situated in the middle and is twice as long as the recesses 81. The length (considered in the plane of the drawings) of the recess 80 is slightly larger than the length of the intermediate surfaces 82 between the recesses 80 and 81. The length of the recess 80 may approximate the length of the recess 81 + the length of surface 82. The distance 83 of the recess 81 to the vertex H may be equal to the length of the surface 82.

The block 1b of figures 5A-C except as regards the details of the fifth side 78b is in fact a mirror image of block 1b, wherein the mirror line coincides with the line U that bounds the side 78a of block 1a. The side 78b is provided with a number of shallow recesses 84 and 85, wherein the recess 84 is in the middle and is shorter than the recesses 85. The length (considered in the plane of the drawing) of the recess 85 is larger than the length of the surfaces 86 between the recesses 84 and 85. The length of the recess 85 may approximate the length of the recess 84 + the length of the surface 86. The distance 83 of the recess 85 to the vertex H may be equal to the length of recess 84.

The length of the recesses 80 and 85 may be equal to each other, the same goes for the length of the recesses 81 and 84. The recesses 80,81 ,84,85 end in a step 80a, 81 a, 84, 85a that are situated at a same distance from the lower surface as the step 13 of recess 11. Below those steps the side 78a, b is still slightly receded, wherein the contact surfaces are formed by the surfaces 82,83,86 that continue to the bottom. In that way short contact surfaces are created and also a small passage for water that is under pressure below the blocks. In a simple, alternative embodiment the side 78a, b continues below the said steps in longitudinal direction in order to form one flat contact surface.

As an example the recesses 80,81 ,84,85 may have a depth of 1.5cm and a length (in circumferential direction) of 3cm or 6cm, respectively. As a result in case of blocks a,b placed with the sides 78a, b against each other, a series of combined recesses is obtained having a width of at least 3cm, which is advantageous for filling those spaces with grit.

The corner areas 9a, b of the blocks 1a,b in this example are designed without a recess like the corner areas 9 have, but in an alternative embodiment they can also be provided with such a recess.

With the blocks 1a and with the blocks 1b assemblies of blocks can be made which at one longitudinal edge or at both longitudinal edges deviate from assemblies 100. In figure 6A an assembly 100a is shown, which at a longitudinal edge is provided with a series of blocks 1a. The other series consist of blocks 1. In that way the assembly 100a has a stretched longitudinal edge F, formed by consecutive side surfaces 78a. In figure 6B an assembly 100b is shown, which at a longitudinal edge is provided with a series of blocks 1b. The other series consist of blocks 1. In that way the assembly 100b has a stretched longitudinal edge F, formed by consecutive side surfaces 78b.

In figures 6A and 6B it is indicated that the mutual centre to centre distance between parallel series of blocks 1 , the distance between series lines containing the centre lines S, is 1.5(a), like in assembly 100. The same applies to the distance from the series line that passes through the points Sa or Sb to the series line of the adjacent series of blocks 1. The distance of the series line through the points Sa (or Sb) to longitudinal edge F is half said distance, ¾(a).

This makes it possible to incorporate the assemblies 100a and 100b in a transverse series of assemblies that for the majority consist of blocks 1 , preserving a pattern measure in transverse direction of 1.5(a).

In figures 7A and 7B a transverse series of assemblies 100a, 100, 100 and 100b is shown. The X direction is the horizontal direction along the slope, the Y direction upwards along the slope. The blocks 1a of the assembly 100a form the upper longitudinal edge, that is stretched and is able to properly connect to a curb or another stretched boundary. The blocks 1b of assembly 100b form the lower longitudinal edge, for which the same can be said. The path size in Y direction is a multiple of 1.5(a) (in this case 15 x 1.5(a) + 2 x ¾(a)), a multiple of said centre to centre distance. The shown transverse series can be continued in X direction with the same transverse series.

In figures 8A and 8B a transverse series of assemblies 100a, 100b, 100a and 100b is shown. The X direction is the horizontal direction along the slope, the Y direction upwards along the slope. The blocks 1a of the assembly 100a again form the upper longitudinal edge and the blocks 1b of assembly 100b again form the lower longitudinal edge. Both assemblies 100 of figures 7A and 7B have been replaced by a pair of assemblies 100a, 100b without the distance between the upper longitudinal edge and the lower longitudinal edge changing. The path size in Y direction again is a multiple of 1.5(a) (in this case 14 x 1.5(a) + 4 x ¾(a)), a multiple of said centre to centre distance. The shown transverse series can be continued in X direction with the same transverse series.

This is advantageous in the transition from a straight slope surface to a curved slope surface, see figure 9. In there it is indicated that a stretched slope surface covered with assemblies 100 in range line R1 changes into a curve section which for instance at range line R2 again changes into a straight slope section. The farther away from the fictional point of curvature, the longer the distance to be followed in direction X will be. The interlocking of the zig-zag-shaped longitudinal edges of the assemblies 100 may cause a problem there. This problem is largely solved by continuing the assemblies 100 in range line R1 with pairs of assemblies 100a, 100b in accordance with figures 8A,B so that each track N1 ,N2 and N3 is formed by a series of pairs of assemblies 100a, 100b, up to range line R2. The stretched longitudinal edges F provide great liberty in the relative position of the assemblies in the respective tracks N1 ,2,3. Depending on the strength of the curvature it is possible to incorporate series of standard assemblies 100 between a pair of assemblies 100a, 100b in a track.

In figure 8C it is shown in detail that at the meeting surface F of the blocks 1a and 1b a series of flat recesses is formed, in which grit can be washed in. For instance recess 80 forms a passage 103 with the rounded corners of two blocks 1b, the recess a passage 104 with the rounded corners of two blocks 1a, and the recesses 81 passages 105 with the recesses 85. If the blocks 1a in longitudinal direction are situated differently with respect to the blocks 1 b a sufficient number of recesses or a sufficient length thereof will be available at all times. The formed passages or grit accommodation spaces may have a size transverse to the divisional plane F of a few cm, for instance approximately 3cm. A grit particle of for instance 25-30mm may for instance fully cross the passage in that direction as a result of which the locking action is strongly enhanced.

It is also possible to place the blocks 1a and 1 b in two series adjacent to each other, wherein the sides 78a, b will form the outer edges. It is also possible to use assemblies of blocks wherein the one longitudinal edge is formed by blocks 1a and the opposing longitudinal edge by blocks 1b, with the sides 78a, 78b parallel to each other wherein between two series of blocks 1a, 1b one or more series of blocks 1 are situated. The grit used for filling the recesses in the assemblies 100, 100a, 100b can advantageously be grit obtained from ultra basic deep rock containing Mg- containing olivine, particularly from peridotite, particularly from dunite. The content of Mg in the olivine preferably is over 50%, particularly over 70%. Especially usable is forsterite, due to its high Mg content. Said olivine breaks down due to reaction with CO2 and water, wherein CO2 is converted into a bicarbonate-ion in solution, and thus is extracted from the atmosphere. The olivine grit is relatively hard (comparable to quartz).

Olivine may well be used as a replacement for the usual grit in coverings of water courses. During and after breaking down it has additional functions, in binding CO2 and extracting heavy metals from the water. The grit between the blocks, in particular in the corner areas 9/102 between the blocks, thus has many functions, including securing the blocks one to the other.

The grit may have a size of over 10mm and be smaller than or equal to 32mm.

In figure 10A a set of blocks 1 is indicated after the mould has been removed. The blocks 1 are then shape-retaining. The set of blocks 1 are brought together, see figure 10B and then joined with a same set of blocks 1 in order to form a group of 16 blocks 1 , which as one unity can be moved by a brick clamp.

In figures 10C-E a combination 200 of covering blocks, here with blocks 1 , and a mat 150 is shown. The mat 150 is permeable to water in three directions (C,D,E also see figure 10E) that are perpendicular to each other. The mat 150 may for instance have a height of 1cm. The strength of the mat 150 is such that the weight of the blocks does not flatten the mat. The internal space of the mat may be filled with fine granular material, that is upwardly stopped by the grit between the blocks. The mat 150 may particularly be an Enkamat (registered trademark), available from Colbond BV. An example is the Enkamat 7020, which is schematically shown in figure 10D, with loops 151 and open spaces 152.

On two sides the mat 150 projects with strips 150a, 150b, for improved connection with adjacent assemblies 200 in the work.

After the blocks 1 have been brought in a group of 16 blocks 1 , figure 10B, said group is provided with an adhesive 160 at the lower surface 3, which adhesive adheres the material of the blocks, particularly concrete, to synthetic material, and subsequently as a group is placed on the mat 150. Alternatively the upper surface of the mat 150 can be provided with said adhesive. The mat 150 and the blocks are brought into contact with each other in order to realise the mutual adhesion.

The assemblies 200 are placed on a slope, see figure 10E, on a layer 302 of granular material that sits on a filtering cloth 301. Water propelled in the layer 302 and possibly causing an unwanted high pressure below the blocks 1 , is able to disperse within the mat 150 to the closest passages 101 and deflect upwards, direction B.

The block 401 of the figures 11A-C as regards the prism main shape corresponds with block 1. The upper surface 402 comprises a central plane 404 that is perpendicular to the prism centre line S. Instead of, like in block 1 , in which the central plane 4 is hexagonal and from each hexagonal side via the descending edge surfaces 6a, b belonging to the upper surface ends in the side surfaces 7,8, the central plane 404 alternately continues level up to the circumferential surface 407,408 (edge portions 411) and from side 405 via descending plane 406a (for instance at 70 degrees to the vertical) continues up to said circumferential surface (edge portions 412). Thus the central plane 404 is enlarged in outward direction with plane portions 404a, as a result of which, see figure 1 B, a substantially triangular plane is obtained. In that way (also see figure 11C) the stability when stacking is considerably increased. In case of a stack or pack of groups or assemblies of blocks 401 , see figure 12, a pallet can be dispensed with. It is furthermore advantageous that the recesses 4 1a that end up in the edge portions 4 are extended with respect to the recesses 411b in the corner areas near the edge portions 412, as a result of which at that location even more grit can be kept confined, which is advantageous for the interlocking of blocks meeting in the corner areas.

The assembly 500 of figures 13A and 3B is also particularly suitable for incorporation in said curve trajectory. Moreover the assembly 500 itself can be properly and stably stacked without placing pallets in between. The assembly comprises four series of blocks and is nominally four blocks long and has four stretched sides, so that in fact a surface of 16 blocks is provided. At the one longitudinal side there are three blocks 1a according to figures 4A-C, at the other longitudinal sides four blocks 1b according to figure 5A-C. They enclose seven blocks 1 according to figure 1A-C. The rectangle is completed by half fitting blocks 1c,1d,1e and 1f. The width of the assembly is 6(a), wherein (a) is the length of the side of the perimeter surface Z, as described above. With the dimensions indicated earlier the assembly 500 has a length of 1.16m and a width of more than 1m.

The half fitting blocks 1c-f differ from each other. The block 1c has a side 8 and two sides 7, therefore an exact left half of block 1 of figure 1 B. The block 1e forms the other half, on the understanding that the fourth sides 78c and 78e of the blocks 1c and 1e are respectively provided with a projection 90 and a recess 95 that extend over the full height of the block and fit into each other for a concave-convex connection so that shifting of assemblies 500 consecutive in a longitudinal series is prevented. Special is that in the front edge of the projection 90 a recess 91 is provided, which starts at a distance from the lower surface at the location of step 92. Apart from the projections 90 and recesses 95 two recesses 93 (block 1c) and 96 (block 1e) are provided, which start at a step 94,97. The steps 92,94 and 97 are at the same level as the steps 13, 80a, 81 a, 84a, 85a.

The half blocks 1d and 1f substantially correspond with respectively the right and the left half of the block 1a of figure 4B. These blocks as well are slightly deviating, due to the presence of said projection 90, recess 95 and recesses 93,96 in the fourth sides 78d and 78f.

When two assemblies 500 with their transverse sides are placed against each other the recesses 91 form small funnel-shaped cavities and the opposite recesses 93-96 form slightly wider funnel-shaped cavities that can be filled with wash-in grit, as a result of which the stability is enhanced. Between the blocks 1 and 1a-f triangular funnels 102 are formed, as discussed above, that are also filled with wash-in grit.

With the blocks according to the invention coverings can be formed that have a percentage of open space (passages) in the range of 8-15%.

The above description is included to illustrate the operation of preferred embodiments of the invention, and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert.