Multilayer concrete block for a surface covering laid in an interlocking manner and surface covering

Abstract

What is described is a concrete block (1), in particular in the form of a surface covering element, which can be laid in an interlocking manner, for creating a surface covering. The concrete block has at least a multilayer concrete block body (2) with at least a concrete block lower side (2.1) and a concrete block upper side (2.2) on the opposite side from the latter. The multilayer concrete block body (2) comprises at least a first concrete block layer (2a) arranged on the concrete block upper side (2.2), at least a second concrete block layer (2b) adjoining the first concrete block layer (2a), and also a third concrete block layer (2c) adjoining the second concrete block layer (2b). The third concrete block layer (2c) forms the concrete block lower side (2.1), which is provided for support on a bedding layer (3) of an underlying surface. The second concrete block layer (2b) arranged between the first and third concrete block layers (2a, 2c) is a porous core layer. The concrete block is in particular characterized in that the first concrete block layer (2a) has a first porosity (P1) and comprises pores with a first pore size distribution (q1), in that the second concrete block layer (2b) has a second porosity (P2) and comprises pores with a second pore size distribution (q2), and in that the third concrete block layer (2c) has a third porosity (P3) and comprises pores with a third pore size distribution (q3), wherein an average pore size of the pores in the third concrete block layer (2c) is smaller than the average pore size of the pores in the second concrete block layer (2b).

Description

[0001] Multi-layer concrete block for a bonded surface covering and surface covering

[0002] Technical area

[0003] The invention relates to a multi-layer concrete block for a surface covering laid in a composite manner and to a surface covering made of such multi-layer concrete blocks.

[0004] State of the art

[0005] Particularly in urban areas, large areas of the surface are designed as walkable or drivable traffic areas such as streets, paths, squares or parking lots and are covered with surface coverings. The surface coverings are often created by laying individual stones, particularly shaped concrete blocks, in a composite manner. For example, such surface coverings are created by paving, whereby paving stones or corresponding shaped concrete blocks are laid in a composite manner on a bedding layer of the subsoil. As a rule, joints remain between adjacent concrete blocks or shaped stones, particularly concrete paving stones, which are filled with suitable, usually sand-like or chipping-like jointing materials. Such surface coverings in the form of paving are well known in the art.

[0006] It is also known to use multi-layered concrete blocks or concrete paving stones for the construction of such a surface covering. These multi-layered concrete blocks typically have at least a core layer and a facing layer. The core layer is usually made of core concrete and forms the core of the concrete block, while the facing layer is usually made of facing concrete and forms the walkable or driveable upper surface of the concrete block, namely its visible surface.

[0007] It is also known that the multi-layer concrete blocks of the type mentioned are designed in such a way that they have a specific or desired water permeability or water permeability and / or a specific or desired water storage capacity due to their structure and the nature of the individual layers, in particular due to the nature of the concrete used to produce the individual layers.

[0008] For example, DE 10 2012 100 616 B4 discloses a surface covering made of two-layered shaped blocks, which have a water-absorbing, water-permeable layer below a substantially water-impermeable layer on the surface, so that the impinging rainwater can flow downwards both via the joints and via the water-permeable layer of the shaped blocks, thus via an infiltration path through the concrete blocks themselves.

[0009] It is also known from the prior art that, if necessary, rainwater can also be stored and thus a so-called urban "heat island effect" can be counteracted through increased water evaporation, since evaporative cooling occurs when water evaporates. Such concrete blocks, which also have a multi-layer structure, are known, for example, from EP 3 889 351 A1 or DE 10 2020 108 785 A1 and have, in particular, three layers.

[0010] However, the concrete block known from EP 3 889 351 A1 has the disadvantage that the watertightness of the lower, third layer can lead to the formation of waterlogging and thus to oversaturation of the middle, second layer. This delays the onset of the evaporation effect or makes it only possible to a limited extent, thus limiting the evaporation properties. The formation of waterlogging in the concrete block during freeze / thaw cycles can also lead to damage to the concrete block.

[0011] In light of ongoing global warming, the demand for surface coverings with effective evaporation properties to positively influence the urban climate is increasing. Therefore, there is a continued need for improved concrete blocks.

[0012] Description of the invention

[0013] The object of the present invention is therefore to provide a concrete block that overcomes the disadvantages of the prior art and that exhibits reliably and permanently improved evaporation properties. This object is achieved according to the invention by the concrete block according to independent claim 1. Furthermore, to achieve the object, a surface covering made of the aforementioned concrete blocks according to claim 15 is proposed, as well as a method for producing such a concrete block according to claim 16. Further advantageous aspects, details, and embodiments of the invention emerge from the dependent claims, the description, and the drawings.

[0014] The present invention provides a concrete block, in particular in the form of a surface covering element that can be laid in a composite manner for creating a surface covering. The concrete block has at least one multi-layer concrete block body with at least one concrete block underside and a concrete block top side opposite thereto. The multi-layer concrete block body comprises at least one first concrete block layer arranged on the concrete block top side, at least one second concrete block layer adjoining the first concrete block layer, and furthermore a third concrete block layer adjoining the second concrete block layer. The third concrete block layer forms the concrete block underside, which is intended to be laid on a bedding layer of a subsurface. The second concrete block layer arranged between the first and third concrete block layers is a core layer with high porosity.The first concrete block layer has a first porosity and comprises pores with a first pore size distribution. The second concrete block layer has a second porosity and comprises pores with a second pore size distribution, and the third concrete block layer has a third porosity and comprises pores with a third pore size distribution. The average pore size of the pores in the third concrete block layer is smaller than the average pore size of the pores in the second concrete block layer.

[0015] The pores present in the individual concrete block layers can also be understood here as the total number of pores in the respective layers or as the sum or total number of pores present in the respective concrete block layers. The pores of a respective concrete block layer thus represent, in their entirety, a void or void volume within the concrete block layer, namely within the total volume of the concrete block layer. In this sense, "porosity" is to be understood as the ratio of the void volume to the total volume of the respective concrete block layers. A porosity value can, for example, also be determined or specified indirectly via a so-called pore factor related to the porosity, where the pore factor is defined as the ratio of the void volume to the solid volume within a respective concrete block layer.

[0016] The term "pore size distribution" in this context refers in particular to the distribution of the pores in the respective concrete block layers in relation to their size, namely the pore size. The pore size, which in this context can also be understood as pore volume, correlates with dimensions of the pores, such as length, width, and height, and can be determined or specified, for example, via a diameter of the pores, i.e., via a pore diameter. Since the individual pores in the concrete block layers are, in particular, geometrically irregular in shape, the pore diameter can also be understood in this context as a pore diagonal.

[0017] For example, the porosity of the concrete block layers and the pore size of the pores in the concrete block layers can be determined using thin-section microscopic examinations known to those skilled in the art. For the purposes of the present invention, the pore size or pore volume can therefore also be specified as pore area, which can be determined in particular by thin-section microscopy. Such a pore area, determined according to thin-section microscopy evaluations, correlates with the pore volume or pore size and can therefore serve as an indication of the pore size.

[0018] A porous concrete block layer, in the sense of the invention, is understood to be a concrete block layer made from a porous concrete material. Such a porous concrete or core concrete generally has defined cavities between the aggregate particles, as defined, for example, in DIN 18507. Unlike DIN 18507, namely the water permeability defined under section 4.3 and the compressive strength defined under section 4.4, the porous concrete used in an advantageous embodiment of the invention has a water permeability kf of less than 1 x 10-5 m / s or an average water permeability kf of less than 1.5 x 10-4 m / s and / or a compressive strength of at least 50 N / mm 2 on.

[0019] The many pores present in a given concrete block layer are different from one another and have different pore sizes. This means that smaller and larger pores occur side by side, with the pores being distributed over a specific or predetermined size range or across a size spectrum, i.e., the pores are present in a predetermined "pore size distribution." Each concrete block layer contains pores up to a maximum pore size, which can be determined, for example, by means of thin-section microscopic examinations. For example, the pore size distribution considered here takes into account all pores that have a size ranging from a selected or fixed or predetermined minimum size, namely a minimum pore size, up to the maximum pore size.

[0020] The "mean pore size" in the present understanding is the average value or the mean value of the pore size of all pores within the relevant size range, namely from the minimum to the maximum pore size.

[0021] The present concrete block, which can also be referred to synonymously as a paving block or concrete paving block, is thus constructed in at least three layers. The concrete block, in particular a concrete paving block, is advantageously manufactured as a single-piece or one-part molded body or concrete block body, i.e., all three concrete block layers are produced in one manufacturing process in the form of a single block, for example, in a paving block machine, i.e., in a manufacturing process using a paving block machine.

[0022] In the present concrete block, particular advantages arise from the layer structure with the properties according to the invention, in particular the porosity of the layers, since these interact particularly advantageously due to their properties in order to keep the second concrete block layer arranged between the first and third concrete block layers, that is to say the middle, porous concrete block layer, moist when the concrete block is in use, namely when laid in the surface covering, but at the same time to prevent waterlogging in order to reliably ensure an effective evaporation effect.

[0023] In particular, the interaction of the concrete block layers ensures that the second concrete block layer, formed as a core layer with a high porosity, absorbs and stores water due to its porosity and permeability. On the one hand, the water can be absorbed in the form of precipitation, penetrating, for example, the first concrete block layer and / or the lateral surfaces or flanks, namely the concrete block sides, into the middle second concrete block layer and being "held" there.

[0024] The "storage" of water in the second concrete block layer can also be understood in this case as an inhibition of the gravity-induced flow of water through the concrete block, whereby the water is "held back" in particular by means of a reduced water permeability of the lower third concrete block layer, thereby counteracting a "leakage" or "drying out" of the second concrete block layer. In other words, the third concrete block layer, due to its lower water permeability, ensures that the water contained in the water-absorbing and water-storing second concrete block layer does not flow unhindered downwards into the bedding layer, but is retained in the second concrete block layer.

[0025] In the present concrete block, due to the inventive nature and design of the concrete block layers, it is simultaneously ensured that water is also "sucked in" from the subsoil via capillary action of the lower, third concrete block layer and can thus be absorbed through the lower, third concrete block layer into the middle, second concrete block layer.

[0026] The capillary effect of the lower, third concrete block layer lying on the bedding layer of the subsoil in use can also be referred to in the present case as suction effect or suction force, whereby the reliable, safe and effective capillary effect or suction effect or suction force is determined in particular by the porosities of the concrete block layers provided according to the invention and advantageously matched or adjusted to one another.

[0027] In other words, in this case we can also speak of a capillary system, particularly in the third layer of concrete blocks, through which, for example, in the event of a lack of precipitation, the middle, second layer of concrete blocks can be supplied with water from the subsoil in order to enable, maintain or ensure the evaporation reactions reliably and, in particular, sufficiently and continuously. The capillary effect, in particular of the lower, third layer of concrete blocks, namely its property of transporting water upwards against gravity, can also be referred to in this case as capillarity. The absorption of precipitation water into the second layer of concrete blocks in the present concrete block can, depending on the design of the first layer of concrete blocks, take place both via this first layer and via the side flanks of the concrete block. It is also conceivable that the absorption of precipitation water takes place mainly or partly via the first layer of concrete blocks.essentially, or possibly exclusively, via the sides of the concrete block. When rainwater is absorbed via the sides or sides of the concrete block, the water penetrates from the joints or from the joint space, i.e., from the joints formed between the individual concrete blocks and filled with joint material, into the porous core layer or diffuses into the porous core layer, preferably into its inner areas.

[0028] Preferably, the average pore size of the pores in the third concrete block layer corresponds to at most 0.3 to 0.6 times, in particular at most 0.4 to 0.5 times, the average pore size of the pores in the second concrete block layer. The value of the average pore size of the pores in the third concrete block layer is thus so much smaller that it is preferably between 30% and 60% of the average pore size of the pores in the second concrete block layer, particularly preferably between 40% and 50% of the average pore size of the pores in the second concrete block layer.With such a ratio of the average pore sizes of the pores in the second and third concrete block layer, a particularly efficient capillary effect as well as stable moistening and a particularly lasting, long-lasting moistening of the porous second concrete block layer and consequently the evaporation effect are achieved.

[0029] Furthermore, the average pore size of the pores in the first concrete block layer is preferably smaller than the average pore size of the pores in the second and third concrete block layers. In these preferred embodiments, all three concrete block layers are coordinated with each other in terms of their pore size distribution in order to reliably maintain a particularly effective evaporation reaction in the concrete block overall, and in particular, largely independent of precipitation.

[0030] Particularly preferably, the average pore size of the pores in the first concrete block layer corresponds to at most 0.1 to 0.3 times, in particular at most 0.2 times, the average pore size of the pores in the second concrete block layer. According to a particularly preferred embodiment, the average pore size of the pores in the third concrete block layer corresponds to at least 3 to 4 times the average pore size of the pores in the first concrete block layer.

[0031] If the mean pore size is again given as a pore area determined by means of thin section microscopy and corresponding evaluations, the mean pore area or pore size can preferably be around 30,000 pm for the pores of the first concrete block layer, for example. 2 for the pores of the second concrete block layer around 262,000 pm 2 and for the pores of the third concrete layer around 108,000 pm 2 .

[0032] A "pore area fraction" determined by thin-section microscopic examinations and evaluations—namely, the determined pore area in relation to the examined area of ​​the concrete block layer—correlates directly with the porosity, which is defined as the ratio of the pore or void volume to the total volume. The "pore area fraction" can therefore be understood here as an expression of the porosity.

[0033] For example, the pore area ratio of the concrete block in question can be 5.3% in the first layer, approximately 7.8% in the second layer, and approximately 4.8% in the third layer. This means that the respective porosities of the first and third layers are in a similar range, i.e., close to each other, but the pores have completely different pore size distributions, and the respective mean pore sizes differ significantly from each other.

[0034] Preferably, each of the concrete block layers has a number of pores that exceeds a minimum pore size, wherein the number of pores with at least the minimum pore size in the second and third concrete block layers is the same or substantially the same or differs from each other by at most 10%. Furthermore, the number of pores with the minimum pore size in the first concrete block layer is preferably higher than in the second and third concrete block layers, in particular 5- to 6-fold higher.

[0035] Pores with at least the minimum pore size are, for example, those pores whose pore diameter or pore diagonal is at least around 5 pm to 10 pm and / or whose pore area (determined, for example, by thin-section microscopic evaluation) is larger than 100 pm 2 .

[0036] Preferably, each of the concrete block layers comprises, in the entirety of its respective pores, pores with a maximum pore size, wherein the maximum pore size of the pores of the first concrete block layer is smaller than the maximum pore size of the pores of the second and third concrete block layers. Alternatively or additionally, the maximum pore size of the pores of the third concrete block layer is smaller than the maximum pore size of the pores of the second concrete block layer.

[0037] According to a particularly preferred embodiment of the present concrete block, the second concrete block layer arranged between the first and third concrete block layers is made of a porous core concrete, and the concrete block is designed in particular to absorb and store water in the second concrete block layer. The porous second concrete block layer thus forms a water-storing layer capable of absorbing water, with the water being retained or stored in the second water-storing layer—in particular through the interaction of all three concrete block layers.

[0038] The first concrete block layer is preferably designed as a facing concrete layer and is, in particular, a concrete block layer made of dense concrete, namely a dense concrete block layer. Advantageously, the first concrete block layer is made of earth-moist concrete, preferably earth-moist concrete with green strength.

[0039] It is understood that for the production of the first concrete block layer, which forms the visible side, namely the surface that can be driven on or walked on, when the concrete block is laid, aggregates can be used in the concrete in order to be able to vary and adapt the visual impression and / or the haptic properties of the first concrete block layer.

[0040] The third concrete block layer, which is preferably also a dense concrete block layer, advantageously has a capillary suction effect for sucking water from the underside of the concrete block through the third concrete block layer into the second concrete block layer. Due to this suction effect, the "water supply" of the second concrete block layer can be significantly improved even during dry periods, for example, in the absence of precipitation, by "sucking in" moisture or water from the bedding layer or from the subsoil and transporting it via capillary action into the concrete block, particularly into the second concrete block layer. The third concrete block layer thus advantageously has capillarity and can therefore transport water upwards against the force of gravity.

[0041] Preferably, the third concrete block layer has a lower water permeability than the second concrete block layer and is designed in such a way that a gravitational water flow through the third concrete block layer is reduced in volume, in particular throttled. This allows the storage effect of water in the second concrete block layer to be further improved or increased, thereby maintaining an effective and reliable evaporation effect of the concrete block even over longer or prolonged periods.

[0042] The porosity or pore content of the individual concrete block layers can be adjusted during the production of the concrete block by selecting appropriate concretes or

[0043] Concrete materials for the production of the individual concrete block layers are adjusted and implemented in the specified, coordinated manner. Preferably, the porosity or pore content is adjusted by appropriately selecting the aggregate and / or the aggregate material. In particular, this can be achieved by using aggregates and / or aggregates with predetermined, specific grading curves, for example, with a grading curve that deviates from a so-called "steady grading curve," in particular with so-called "dropout gradings."

[0044] A "steady grading curve" is a grading curve that increases with a constant gradient, i.e. the different grain fractions are each contained in equal proportions.

[0045] For example, the second concrete block layer with its second porosity can advantageously be made from a concrete material with a predetermined grain size, in particular with a selected predetermined grain size that has a higher coarse fraction than a continuous grading curve, whereby individual grain groups can also be deliberately omitted or reduced when constructing the grading curve. For example, the predetermined grain size for the second concrete block layer can be selected such that the coarse fraction is higher than a continuous grading curve, the middle range is reduced or almost completely absent, and in the fine range (up to 2.0 mm) only enough aggregate is present to create just enough glue to firmly and permanently bond the coarse grains together, thus achieving the specified strength.

[0046] The third concrete block layer, in turn, can preferably be made from a concrete material with a reduced fine particle content, in particular with a fine particle content of the aggregate grading curve that is reduced compared to a continuous grading curve, thereby specifically improving the absorbent properties of the third concrete block layer. Fine particle includes all substances in the concrete with a grain size of 0.125 mm or less. Accordingly, the fine particle content is composed of the cement and the grain fraction up to 0.125 mm contained in the aggregate, as well as any concrete additives. Most preferably, the fine particle content of the aggregate grading curve of the concrete material used to produce the third concrete block layer is reduced by around 60% compared to a continuous grading curve.

[0047] Above, the concrete block was described as a three-layer concrete block with exactly three concrete block layers. However, it is understood that additional layers may be provided between the first and third concrete block layers, as long as the relative arrangement of the described first, second, and third concrete block layers, including their composition and properties, is maintained, thus maintaining their interaction with regard to water absorption and storage, as well as capillary transport.

[0048] The present invention also relates to a surface covering comprising a plurality of multi-layer concrete blocks, as described above, laid in a composite manner on a bedding layer of a subsurface. In the surface covering, joints are formed between adjacent concrete blocks, which are filled with a substantially grit- and / or sand-like jointing material and form an infiltration path for draining rainwater from a surface of the surface covering. Furthermore, the surface covering is designed to absorb and store water and is configured to provide water for evaporation across the surface of the surface covering.

[0049] Furthermore, the present invention relates to a method for producing a concrete block described above. In the method, after providing a formwork, concrete is introduced into the formwork in a first step to produce the third layer of concrete blocks. In a second step to produce the second layer of concrete blocks, additional porous core concrete is then introduced into the formwork, and in a third step to produce the first layer of concrete blocks, a facing concrete is introduced into the formwork. The introduced concrete material is then compacted and cured.

[0050] After the concrete has hardened, the formwork is removed. Optionally, or alternatively, the formwork can also be removed before or after partial hardening.

[0051] Short description of the drawings

[0052] The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawings.

[0053] Fig. 1 shows a highly simplified and roughly schematic perspective view of an embodiment of a concrete block according to the invention;

[0054] Fig. 2 shows a roughly schematic section through the concrete block of Figure 1;

[0055] Fig. 3 shows a highly simplified sectional view of a schematic section through a surface covering section produced using concrete blocks according to Figures 1 and 2,

[0056] Fig. 4 is a schematic, enlarged and highly simplified section through the surface covering section according to Figure 3 to explain the water absorption and evaporation by means of the concrete blocks in question and

[0057] Fig. 5a-c each show in the form of a histogram a respective pore size distribution of the pores of the concrete block layers.

[0058] Ways to implement the invention

[0059] Identical reference numerals are used in the figures for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals are shown in the individual figures that are necessary for the description of the respective figure. Figure 1 shows, by way of example, a highly simplified schematic drawing of a perspective view of an embodiment of the concrete block 1 according to the invention, and Figure 2 shows a schematic section along a sectional plane running parallel to a central vertical axis MHA and parallel to a longitudinal axis LA of the concrete block 1.

[0060] The concrete block 1 is preferably designed in the form of a surface element that can be laid in a composite manner to create a surface covering 10 (see Figure 3). In the present case, concrete block 1, which can also be referred to synonymously as a concrete slab or paving stone, essentially refers to structurally identical elements that can be used in a conventional manner to create a surface covering 10, in particular a driveable concrete block pavement. For example, the concrete block 1 can be a concrete paving stone. Depending on the selected laying pattern, the concrete blocks 1 are laid in a composite manner, for example, interlocked, and flush with one another, so that a preferably flat surface covering 10 is created.

[0061] The concrete block 1 comprises at least one multi-layered concrete block body 2 with at least one flat concrete block underside 2.1 and, opposite this, a substantially flat concrete block upper side 2.2, which preferably forms the walking surface or driveable surface or traffic area. The specific design of the lateral surface sections of the concrete block 1 is not relevant to the invention, i.e., the specific cross-sectional shape of the concrete block 1 can be selected almost arbitrarily without departing from the inventive concept.

[0062] In the present exemplary embodiment, the concrete block 1 is cuboid-shaped and has two pairs of two opposing concrete block sides 2.3, 2.4 with equal areas. The concrete block bottom side 2.1 and the concrete block top side 2.2 run perpendicular or approximately perpendicular to the central vertical axis MHA of the concrete block body 2 or concrete block 1. The pair of concrete block sides 2.4 extend substantially perpendicular to the longitudinal axis LA, and the concrete block sides 2.3 extend substantially parallel to the longitudinal axis LA.

[0063] The illustrated multi-layer concrete block body 2 comprises at least one first concrete block layer 2a, designed as a facing concrete layer and forming the concrete block top 2.2, at least one second concrete block layer 2b adjoining the first concrete block layer 2a in the direction of the central vertical axis MHA, and a third concrete block layer 2c adjoining the second concrete block layer 2b in the direction of the central vertical axis MHA, which forms the concrete block bottom 2.1 and is intended to be supported on a bedding layer 3 of a subsurface. In the example illustrated, the first and second concrete block layers 2a, 2b, as well as the second and third concrete block layers 2b, 2c, are each directly and immediately adjacent to one another.

[0064] The second concrete block layer 2b arranged between the first and third concrete block layers 2a, 2c is a porous core layer designed to absorb and store water.

[0065] The concrete block 1 has a total height H which preferably corresponds to the sum of the layer thicknesses Da, Db, Dc of the first to third concrete block layers 2a, 2b, 2c. In the present exemplary embodiment, the first concrete block layer 2a has a first layer thickness Da, the second concrete block layer 2b has a second layer thickness Db, and the third concrete block layer 2c has a third layer thickness Dc. For example, the third layer thickness Dc of the third concrete block layer 2c is between 2 mm and 10 mm, preferably between 2 mm and 5 mm. Relative to the total height H of the concrete block 1, the third layer thickness Dc thus has between 1% and 10% of the total height H of the concrete block body 2, preferably between 1% and 5% of the total height H.

[0066] For optimal absorption and storage of water, the second layer thickness Db of the second concrete block layer 2b is between 60% and 90% of the total height H of the concrete block body 2, preferably between 70% and 85% of the total height H of the concrete block body 2.

[0067] In the illustrated embodiment, the concrete block 1 has so-called spacers or spacer lugs 4, which ensure uniform joints 5 (see Figures 3 and 4) of approximately uniform width when laying the concrete block 1 in the composite and ensure a minimum width of the joints 5.

[0068] Each of the three concrete block layers 2a, 2b, 2c essentially represents a porous solid layer and has a predetermined porosity PI, P2, P3. The first concrete block layer 2a, which has a first porosity PI, comprises pores with a first pore size distribution q1 (not visible in Figures 1 and 2, see Figures 5a to 5c), the second concrete block layer 2b, which has a second porosity P2, comprises pores with a second pore size distribution q2, and the third concrete block layer 2c, which has a third porosity P3, comprises pores with a third pore size distribution q3.

[0069] The porosities PI, P2, P3 and the pore size distributions ql, q2, q3 of the individual concrete block layers 2a, 2b, 2c are matched or adjusted to one another in the present concrete block 1 in such a way that the water permeability as well as the water absorption and water storage of the concrete block 1 as well as the capillary water transport are optimized with regard to a reliable, lasting or constant and effective evaporation effect and at the same time waterlogging is avoided.

[0070] Figures 5a to 5c show the pore size distributions q1, q2, q3 of the concrete block layers 2a, 2b, and 2c as examples, each in the form of a histogram. In Figures 5a to 5c, the number n of pores is indicated on the ordinate (y-axis), and the abscissa (x-axis) indicates the pore size A, which in the examples shown is expressed as the pore area A, which was determined by thin-section microscopic analysis (as described in more detail below as Example 1).

[0071] The exemplary diagrams 5a to 5c represent a logarithmic representation, with the abscissa being understood as a logarithmic scale. Figures 5a to 5c thus essentially show the number of pores present (or the frequency of pore occurrence) as a function of their size.

[0072] As can be seen from the illustration in Figures 5a to 5c, all three pore size distributions ql, q2, q3 of the concrete block layers 2a, 2b, 2c described as examples are different from each other, i.e. the size distribution of the pores in the concrete block layers 2a, 2b, 2c is different.

[0073] In the first concrete block layer 2a (see Figure 5a), the pore size distribution ql essentially has a pore maximum, i.e. pores with a pore size of around 10,000 pm 2 are most common. In the second concrete block layer 2b (see Figure 5b), the pore size distribution q2 essentially has two pore maxima, i.e. pores with a pore size of around 1,000 pm 2 and around 100,000 pm 2are most common, with the two pore maxima being approximately equal in size. In the third concrete block layer 2c (see Figure 5c), the pore size distribution q3 essentially has two pore maxima, i.e., pores with a pore size of approximately 1,000 pm 2 and around 100,000 pm 2 are most common, although the first pore maximum (at 1,000 pm 2 ) is significantly larger than the second pore maximum (at 100,000 pm 2 ).

[0074] The respective average or mean pore size of the pores present in the individual concrete block layers 2a, 2b, 2c can be determined, for example, from the corresponding pore size distributions q1, q2, q3. In the example described, the respective mean pore sizes in all three concrete block layers 2a, 2b, 2c are different from one another.

[0075] The average pore size of the pores in the third concrete block layer 2c is smaller than the average pore size of the pores in the second concrete block layer 2b. Likewise, the average pore size of the pores in the first concrete block layer 2a is smaller than the average pore size of the pores in the second concrete block layer 2b and at the same time smaller than the average pore size of the pores in the third concrete block layer 2c.

[0076] The following example, "Example 1", describes how the porosities PI, P2, P3 and the pore size distributions ql, q2, q3 can be investigated and determined.

[0077] Furthermore, based on a "Table 1" explained below, corresponding properties with regard to the porosities PI, P2, P3 of the first, second and third concrete block layers 2a, 2b, 2c are summarized in a table for an exemplary embodiment of the present concrete block 1, wherein the data were obtained via thin section microscopic evaluations (as described in Example 1).

[0078] Example 1: Thin section microscopic examination and determination of the pore content of the samples

[0079] Thin section microscopic examinations are generally known to the person skilled in the art and were carried out in a known manner, with details of the examinations being described in more detail below.

[0080] For the thin-section microscopic examination, a sample of each concrete block layer (2a, 2b, and 2c) was prepared in the form of a polished thin section with a section thickness of approximately 25 μm and a format of approximately 20 mm x 40 mm. For preparation, the samples were embedded in epoxy resin with a fluorescent dye ("epodye"). This fills almost all the pores and makes them microscopically visible due to the color of the epoxy resin.

[0081] The subsequent microscopic examinations were carried out according to Example 1 using a digital microscope unit (Keyence VHX-7000) with appropriate objectives for 20x to 500x magnification. Microscopy was performed using linearly polarized light, followed by false-color imaging. Images were captured using a high-resolution 4K camera (Keyence VHX-7100).

[0082] A quantitative determination of the pores present in the samples of the respective concrete block layers 2a, 2b, 2c was carried out according to Example 1 as a determination of the total pore area in the respective thin section sample, thus as a quantitative determination of the respective total pore area proportions.

[0083] This analysis was carried out using evaluation software with predetermined settings. By color-identifying the dyed epoxy resin, all pores with a pore area A greater than 100 pm were identified. 2 selected and recorded. According to the evaluation settings, pores in aggregates were manually removed and pores with incompletely colored filling were manually added. The number n of recorded pores (each with a pore area A greater than 100 pm 2 ) is therefore the result of the evaluation according to the specified evaluation settings.

[0084] Table 1 : Tabular summary of exemplary test results As Table 1 clearly shows, the second porous concrete block layer 2b has the largest pores (with the largest maximum pore area) as well as the largest total pore area and the largest average pore size.

[0085] In the example shown, the number n of pores in the first concrete block layer is significantly increased compared to the respective number n of pores in the second and third concrete block layers 2b, 2c. Although the proportion of the pore area in the first and third concrete block layers 2a, 2c is comparable or almost the same, significantly more pores are formed in the first concrete block layer 2a than in the third concrete block layer 2c, whereby the pores of the third concrete block layer 2c have a significantly larger average pore size than the pores of the first concrete block layer 2a.

[0086] Due to these porosities P1, P2, P3 of the first, second and third concrete block layers 2a, 2b, 2c with the described pore size distributions q1, q2, q3 as shown by way of example in Figures 5a to 5c and in Table 1 for a preferred embodiment of the concrete block 1, the capillary system in the concrete block 1, in particular in the third concrete block layer 2c, establishes a suction force in order to suck water from the bedding layer of the subsoil against gravity into the concrete block 1, namely into the second concrete block layer 2b, or to transport it by capillary action, where the water can then be "held" or stored due to the porosities in order to be available for efficient evaporation.

[0087] The third concrete block layer 2c has a lower water permeability compared to the second concrete block layer 2b, which is significantly reduced, particularly with regard to gravity-induced water flow. In the present context, a water-permeable layer with low water permeability is understood to mean a concrete block layer through which water can be transported or passed, but with a time delay and / or at a reduced or reduced flow rate, in particular significantly reduced or reduced, compared to the second, water-permeable concrete block layer 2b.

[0088] With reference to Figures 3 and 4, the water transport in a surface covering 10 constructed from a plurality of existing concrete blocks 1 is once again illustrated. The surface covering 10 comprises a plurality of multi-layered concrete blocks 1 laid in a composite manner on a bedding layer 3 of a subsurface. Between adjacent concrete blocks 1 of the surface covering 10, joints 5 are formed, which are filled with a joint material 6 and form an infiltration path for draining rainwater from the surface of the surface covering 10 facing away from the bedding layer 3. The bedding layer 3 is a conventional bedding layer, which essentially consists of a material mixture with a grain size of 0.1 mm to 5 mm.

[0089] The third concrete block layer 2c of the concrete blocks 1 has a capillary suction effect for sucking water from the concrete block underside 2.1 through the third concrete block layer 2c into the second concrete block layer 2b, namely in a first direction RI. This suction effect or capillary effect allows water to be supplied from the bedding layer 3 to the second concrete block layer 2b in the surface covering 10 via the third concrete block layer 2c. As a result, the water-storing second concrete block layer 2b can always be kept moist or wet to promote evaporation V. The third concrete block layer 2c therefore has an "irrigation effect" for the second concrete block layer 2b.

[0090] The "irrigation effect" is particularly advantageous when, due to the capillary suction force of the third concrete block layer 2c, the first direction RI running from the concrete block underside 2.1 to the second concrete block layer 2b is greater than the second direction R2 running from the second concrete block layer 2b to the concrete block underside 2.1.

[0091] The infiltration and absorption path for precipitation water, as indicated in Figure 4 by the simple black arrows, essentially reflects the situation in the event that water is present "in excess" due to precipitation. The precipitation water impinging on the surface of the surface covering 10 on the first concrete block layer 2a of the concrete blocks 1 preferably seeps through the joints 5 into the joint material 6. Depending on the design of the first concrete block layer 2a, the precipitation water can also be passed through and guided by this. Independently of this, at least a sufficient portion of the infiltrating precipitation water moving towards the bedding layer 3 passes from the joint material 6 into the porous second concrete block layer 2b, which, due to its porosity and permeability, is designed for particularly effective water absorption and storage.The porous second concrete block layer 2b, for example, absorbs the water like a sponge. Due to the reduced water permeability of the third concrete block layer 2c, the passage of water in the second direction R2, namely through the third concrete block layer 2c into the bedding layer 3 or the subsoil, is delayed, reduced, or inhibited, and possibly even completely prevented. This delayed, possibly almost blocked, water transport in the second direction R2 is indicated in Figure 4 by dashed arrows, as is the optional water transport through the first concrete block layer 2a.

[0092] Due to the special formation and nature of the porosities PI, P2, P3 of the individual concrete block layers 2a, 2b, 2c and in particular due to their special interaction, the water that has penetrated into the second concrete block layer 2b can be effectively retained or stored there.

[0093] In Figure 4, the capillary water transport through the third concrete block layer 2c into the second concrete block layer 2b, i.e., the capillary water transport, namely the suction effect of the third concrete block layer 2c, is indicated by the double arrows in the first direction RI. This suction effect can ensure the "water supply" of the second concrete block layer 2b even in the event of a lack of precipitation. The precipitation water absorbed and stored in the second concrete block layer 2b, as well as the water "supplied" from the subsoil or the bedding layer 3 via the suction effect of the third concrete block layer 2c, is available for evaporation V, which is thus maintained consistently and, in particular, effectively.

[0094] Reference symbols

[0095] 1 concrete block

[0096] 2 concrete block bodies

[0097] 2a first concrete block layer

[0098] 2b second concrete block layer

[0099] 2c third concrete block layer

[0100] 2.1 Concrete block underside

[0101] 2.2 Concrete block top

[0102] 2.3, 2.4 Concrete block sides

[0103] 3 bedding layer

[0104] 4 spacer lugs

[0105] 5 joints

[0106] 6 Joint material

[0107] 10 Surface covering

[0108] A Pore size, pore area

[0109] Since the layer thickness of the first concrete block layer

[0110] Db Layer thickness of the second concrete block layer

[0111] Dc layer thickness of the third concrete block layer

[0112] H Total height of the concrete block

[0113] LA longitudinal axis

[0114] MHA central vertical axis n number of pores

[0115] PI, P2, P3 first, second, third porosity ql, q2, q3 first, second, third pore size distribution

[0116] RI, R2 first and second direction of water permeability

[0117] V Evaporation

Claims

Patent claims 1. Concrete block (1), in particular in the form of a surface covering element that can be laid in a composite manner for creating a surface covering, comprising at least one multi-layer concrete block body (2) with at least one concrete block underside (2.1) and a concrete block top side (2.2) opposite thereto, wherein the multi-layer concrete block body (2) comprises at least one first concrete block layer (2a) arranged on the concrete block top side (2.2), at least one second concrete block layer (2b) adjoining the first concrete block layer (2a), and furthermore a third concrete block layer (2c) adjoining the second concrete block layer (2b), wherein the third concrete block layer (2c) forms the concrete block underside (2.1).1) which is intended to be laid on a bedding layer (3) of a subsurface and wherein the second concrete block layer (2b) arranged between the first and third concrete block layers (2a, 2c) is a core layer with aggregate porosity, characterized in that the first concrete block layer (2a) has a first porosity (P1) and comprises pores with a first pore size distribution (q1), that the second concrete block layer (2b) has a second porosity (P2) and comprises pores with a second pore size distribution (q2) and that the third concrete block layer (2c) has a third porosity (P3) and comprises pores with a third pore size distribution (q3), wherein an average pore size of the pores in the third concrete block layer (2c) is smaller than the average pore size of the pores in the second concrete block layer (2b).

2. Concrete block (1) according to claim 1, characterized in that the average pore size of the pores in the third concrete block layer (2c) corresponds at most to 0.3 times to 0.6 times, in particular at most to 0.4 times to 0.5 times the average pore size of the pores in the second concrete block layer (2b).

3. Concrete block (1) according to claim 1 or 2, characterized in that the average pore size of the pores in the first concrete block layer (2a) is smaller than the average pore size of the pores in the second and third concrete block layers (2b, 2c).

4. Concrete block (1) according to one of the preceding claims, characterized in that the average pore size of the pores in the first concrete block layer (2a) is at most 0.1 to 0.3 times, in particular corresponds to a maximum of 0.2 times the average pore size of the pores in the second concrete block layer (2b).

5. Concrete block (1) according to one of the preceding claims, characterized in that the average pore size of the pores in the third concrete block layer (2c) corresponds to at least 3 to 4 times the average pore size of the pores in the first concrete block layer (2a).

6. Concrete block (1) according to one of the preceding claims, characterized in that each of the concrete block layers (2a, 2b, 2c) has a number (n) of pores which exceed a minimum pore size, wherein the number (n) of pores with at least the minimum pore size in the second and third concrete block layers (2b, 2c) is the same or substantially the same or differs from one another by at most 10%.

7. Concrete block (1) according to claim 6, characterized in that the number (n) of pores with the minimum pore size in the first concrete block layer (2a) is higher than in the second and third concrete block layers (2b, 2c), in particular is increased 5-fold to 6-fold.

8. Concrete block (1) according to one of the preceding claims, characterized in that each of the concrete block layers (2a, 2b, 2c) in the entirety of its respective pores each comprises pores with a maximum pore size, wherein the maximum pore size of the pores of the first concrete block layer (2a) is smaller than the maximum pore size of the pores of the second and third concrete block layers (2b, 2c) and / or that the maximum pore size of the pores of the third concrete block layer (2c) is smaller than the maximum pore size of the pores of the second concrete block layer (2b).

9. Concrete block (1) according to one of the preceding claims, characterized in that the second concrete block layer (2b) arranged between the first and third concrete block layer (2a, 2c) is made of a porous core concrete and the concrete block (1) is designed in particular to absorb and store water in the second concrete block layer (2b).

10. Concrete block (1) according to one of the preceding claims, characterized in that the first concrete block layer (2a), which is preferably designed as a facing concrete layer, is a structurally dense concrete block layer which in particular made of earth-moist concrete, preferably earth-moist concrete with green strength.

11. Concrete block (1) according to one of the preceding claims, characterized in that the third concrete block layer (2c) has a capillary suction effect for sucking water from the concrete block underside (2.1) through the third concrete block layer (2c) into the second concrete block layer (2b).

12. Concrete block (1) according to one of the preceding claims, characterized in that the third concrete block layer (2c) has a lower water permeability than the second concrete block layer (2b) and is designed in particular such that a gravitational water flow through the third concrete block layer (2c) is reduced in volume, in particular throttled.

13. Concrete block (1) according to one of the preceding claims, characterized in that the porous core layer has a water permeability kf of less than 1 x 10-5 m / s or a water permeability kf on average of less than 1.5 x 10-4 m / s and / or a compressive strength of at least 50 N / mm 2 has.

14. Surface covering (10) comprising a plurality of multi-layer concrete blocks (1) laid in a composite manner on a bedding layer (3) of a subsurface according to one of claims 1 to 13, wherein joints (5) are formed between adjacent concrete blocks (1) of the surface covering (10), and wherein the joints (5) are filled with a substantially chippings- and / or sand-like jointing material (6) and form an infiltration path for draining rainwater from a surface of the surface covering (10), and wherein the surface covering (10) is designed and configured to absorb and store water in order to provide water for evaporation via the surface of the surface covering (10).

15. A method for producing a concrete block (1) according to one of claims 1 to 13, wherein, after providing a formwork, in a first step for producing the third concrete block layer (2c), concrete is introduced into the formwork, wherein, in a second step for producing the second concrete block layer (2b), additionally aggregate-porous core concrete is introduced into the formwork is introduced and in which, in a third step, a facing concrete is introduced into the formwork to produce the first concrete block layer (2a), the introduced concrete material then being compacted and cured.

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