MULTI-LAYER CONCRETE BLOCK FOR A SURFACE COVERING LAID IN BOND AND SURFACE COVERING

Abstract

A concrete block is described in the form of a surface covering element. The concrete block is made of at least one multi-layer concrete block body. The multi-layer concrete block body has a concrete block layer arranged on the concrete block top side, at least one second concrete block layer adjoining the first concrete block layer and a third concrete block layer adjoining the second concrete block layer. The third concrete block layer forms the concrete block underside. The second concrete block layer is a non-fines porous core layer. The first concrete block layer has a first porosity, the second concrete block layer has a second porosity, and the third concrete block layer has a third porosity, wherein a mean pore size of the pores in the third concrete block layer is smaller than the mean pore size of the pores in the second concrete block layer.

Claims

1. A concrete block in a form of a surface covering element which can be laid in bond for producing a surface covering, comprising at least a multi-layer concrete block body with at least one concrete block underside and a concrete block top side opposite thereto, wherein 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, a third concrete block layer adjoining the second concrete block layer, wherein the third concrete block layer forms the at least one concrete block underside, which is for laying on a bedding layer of a substrate, and wherein the second concrete block layer arranged between the first concrete block layer and the third concrete block layer is a non-fines porous core layer, wherein the first concrete block layer has a first porosity and comprises pores with a first pore size distribution, and the second concrete block layer has a second porosity and comprises pores with a second pore size distribution, and in that the third concrete block layer has a third porosity and comprises pores with a third pore size distribution, wherein a mean pore size of pores in the third concrete block layer is smaller than a mean pore size of pores in the second concrete block layer.

2. The concrete block according to claim 1, wherein the mean pore size of the pores in the third concrete block layer corresponds to at most 0.3 times to 0.6 times of the mean pore size of the pores in the second concrete block layer.

3. The concrete block according to claim 1, wherein the mean pore size of the pores in the first concrete block layer is smaller than the mean pore size of the pores in the second concrete block layer and the third concrete block layer.

4. The concrete block according to claim 1, wherein the mean pore size of the pores in the first concrete block layer (2a) corresponds to at most 0.1 times to 0.3 times of the mean pore size of the pores in the second concrete block layer.

5. The concrete block according to claim 1, wherein the mean pore size of the pores in the third concrete block layer corresponds to at least 3 to 4 times the mean pore size of the pores in the first concrete block layer.

6. The concrete block according to claim 1, wherein the first concrete block layer, the second concrete block layer and the third concrete block layer comprises in each case a number of pores which exceed a minimum pore size, wherein the number of pores with at least the minimum pore size in the second concrete block layer and the third concrete block layer is the same, or substantially the same, or differs from one another by at most 10%.

7. The concrete block according to claim 6, wherein the number of pores with the minimum pore size in the first concrete block layer is higher than in the second concrete block layer and the third concrete block layer.

8. The concrete block according to claim 1, wherein the first concrete block layer, the second concrete block layer and the third concrete block layer in a totality of their respective pores in each case comprises 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 concrete block layer and the third concrete block layer, and/or in that 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.

9. The concrete block according to claim 1, wherein the second concrete block layer arranged between the first concrete block layer and the third concrete block layer is produced from a non-fines porous core concrete and the concrete block is designed to absorb and store water in the second concrete block layer.

10. The concrete block according to claim 1, wherein the first concrete block layer, formed as a face concrete layer, is a dense-structure concrete block layer which is produced from an earth-moist concrete.

11. The concrete block according to claim 1, wherein the third concrete block layer comprises a capillary suction effect for sucking water from the concrete block underside through the third concrete block layer into the second concrete block layer.

12. The concrete block according to claim 1, wherein the third concrete block layer comprises a lower water permeability than the second concrete block layer and is designed in such a way that a gravity-induced water flow through the third concrete block layer is reduced in volume, in particular throttled.

13. The concrete block according to claim 1, wherein the non-fines porous core layer comprises a water permeability of less than 1105 m/s or a water permeability on average of less than 1.5104 m/s and/or a compressive strength of at least 50 N/mm2.

14. A surface covering comprising a plurality of multi-layer concrete blocks laid in bond on a bedding layer of a substrate according to any one of claim 1, wherein joints are formed between adjacent concrete blocks of the surface covering, and wherein the joints are filled with a substantially grit join material and/or sand joint material and form a seepage path for draining rainwater from a surface of the surface covering, and wherein the surface covering is equipped to absorb and store water in order to provide water for evaporation via the surface of the surface covering.

15. A method for producing a concrete block according to claim 1 comprising the steps of: providing a formwork: introducing a concrete into the formwork in a first step to produce the third concrete block layer: producing, in a second step, the second concrete block layer, wherein additionally non-fines porous core concrete is introduced into the formwork, and producing, in a third step, the first concrete block layer, wherein a face concrete is introduced into the formwork, and wherein the concrete material introduced is subsequently compacted and cured.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The invention will be explained in greater detail below with reference to exemplary embodiments in conjunction with the drawings, in which:

[0050] FIG. 1 shows a highly simplified and roughly schematic a perspective view of an embodiment of a concrete block according to the invention;

[0051] FIG. 2 shows a rough schematic section through the concrete block of FIG. 1;

[0052] FIG. 3 shows, in a highly simplified sectional view, a schematic section through a surface covering portion produced using concrete blocks according to FIGS. 1 and 2;

[0053] FIG. 4 shows a schematic, enlarged and highly simplified section through the surface-covering portion according to FIG. 3 to explain the water absorption and evaporation by means of the present concrete blocks; and

[0054] FIG. 5a-c each show, in the form of a bar chart, a respective pore size distribution of the pores of the concrete block layers.

DETAILED DESCRIPTION OF THE INVENTION

[0055] Identical reference signs are used in the figures for like or equivalently acting elements of the invention. Furthermore, for the sake of clarity, only reference signs that are necessary for the description of the respective figure are shown in the individual figures.

[0056] FIG. 1 shows by way of example in a highly simplified schematic drawing a perspective view of an embodiment of the concrete block 1 according to the invention and FIG. 2 shows a schematic section along a plane of section running parallel to a centre vertical axis MHA and parallel to a longitudinal axis LA of the concrete block 1.

[0057] The concrete block 1 is preferably designed in the form of a surface element that can be laid in bond with others to create a surface covering 10 (see FIG. 3). In the present case, a concrete block 1, which can also be referred to synonymously as a concrete slab or paving block, is understood to mean substantially structurally identical elements that can be used in a known manner to create a surface covering 10, in particular a concrete block paving that can be driven on. For example, the concrete block 1 may be a concrete paving block. Depending on the chosen laying pattern, the concrete blocks 1 are laid in bond, for example interlocked with one another, and flush with the surface of one another, so that a preferably level surface covering 10 is created.

[0058] The concrete block 1 comprises at least one multi-layer concrete block body 2 with at least one flat concrete block underside 2.1 and a substantially flat concrete block top side 2.2 opposite thereto, which preferably forms the surface that can be walked or driven on, or also traffic surface. The specific configuration of the lateral surface portions 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 chosen almost at will without departing from the concept of the invention.

[0059] In the present exemplary embodiment, the concrete block 1 is cuboid in shape and has two pairs of two concrete block sides 2.3, 2.4, each with the same surface area and opposite each other. The concrete block underside 2.1 and the concrete block top side 2.2 run perpendicular or approximately perpendicular to the center vertical axis MHA of the concrete block body 2 or concrete block 1. The pair of concrete block sides 2.4 extends substantially perpendicular to the longitudinal axis LA and the concrete block sides 2.3 extend substantially parallel to the longitudinal axis LA.

[0060] The multi-layer concrete block body 2 shown comprises at least one first concrete block layer 2a designed as a face concrete layer and forming the concrete block top side 2.2, at least one second concrete block layer 2b adjoining the first concrete block layer 2a in the direction of the center vertical axis MHA and a third concrete block layer 2c adjoining the second concrete block layer 2b in the direction of the center vertical axis MHA, which forms the concrete block underside 2.1 and is intended for laying on a bedding layer 3 of a substrate. In the example shown, the first and second concrete block layers 2a, 2b and the second and third concrete block layers 2b, 2c are directly adjacent to each other.

[0061] The second concrete block layer 2b, arranged between the first and third concrete block layers 2a, 2c, is a porous core layer that is designed to absorb and store water.

[0062] 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. In relation to the total height H of the concrete block 1, the third layer thickness Dc is thus 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.

[0063] To optimize the 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.

[0064] In the exemplary embodiment shown, the concrete block 1 has so-called spacers or spacer lugs 4, which ensure uniform joints 5 (see FIGS. 3 and 4) of approximately uniform width when laying the concrete block 1 in combination and ensure a minimum width of the joints 5.

[0065] Each of the three concrete block layers 2a, 2b, 2c substantially represents a porous solid layer and has a predetermined porosity P1, P2, P3. The first concrete block layer 2a, which has a first porosity P1, comprises pores with a first pore size distribution q1 (not shown in FIGS. 1 and 2; see FIGS. 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.

[0066] The porosities P1, P2, P3 and the pore size distributions q1, q2, q3 of the individual concrete block layers 2a, 2b, 2c of the present concrete block 1 are matched or adjusted to each other in such a way that the water permeability and the water absorption and water storage of the concrete block 1 as well as the capillary water transport are optimised with regard to a reliable, sustained or constant and effective evaporation effect, and at the same time waterlogging is avoided.

[0067] In FIGS. 5a to 5c, the pore size distributions q1, q2, q3 of the concrete block layers 2a, 2b, 2c are shown as examples and each in the form of a bar chart. In FIGS. 5a to 5c, the number n of pores is shown on the ordinate (y-axis) and the abscissa (x-axis) shows the pore size A, which in the examples shown is given as the pore area A, which was determined by means of thin section microscopic evaluations (as described in greater detail below as Example 1).

[0068] The exemplary graphs 5a to 5c show a logarithmic representation, wherein the abscissa is to be understood as a logarithmic scale. FIGS. 5a to 5c thus substantially show the number of occurring pores (or frequency of occurrence of pores) as a function of their size.

[0069] As can be seen from the representation of FIGS. 5a to 5c, all three pore size distributions q1, q2, q3 of the concrete block layers 2a, 2b, 2c described by way of example are different from one another, i.e. the size distribution of the pores in the concrete block layers 2a, 2b, 2c is different.

[0070] In the first concrete block layer 2a (see FIG. 5a), the pore size distribution q1 substantially shows a pore maximum, i.e. pores with a pore size of around 10,000 m2 occur most frequently. In the second concrete block layer 2b (see FIG. 5b), the pore size distribution q2 substantially shows two pore maxima, i.e. pores with a pore size of around 1,000 m2 and around 100,000 m2 occur most frequently, wherein the two pore maxima are approximately the same size. In the third concrete block layer 2c (see FIG. 5c), the pore size distribution q3 substantially shows two pore maxima, i.e. pores with a pore size of around 1,000 m2 and around 100,000 m2 occur most frequently, wherein, however, the first pore maximum (at 1,000 m2) is significantly larger than the second pore maximum (at 100,000 m2).

[0071] A 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 respective 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 each other.

[0072] The mean pore size of the pores in the third concrete block layer 2c is smaller here than the mean pore size of the pores in the second concrete block layer 2b. Similarly, the mean pore size of the pores in the first concrete block layer 2a is smaller than the mean pore size of the pores in the second concrete block layer 2b and at the same time smaller than the mean pore size of the pores in the third concrete block layer 2c.

[0073] In the following, an example, namely Example 1, is used to describe how the porosities P1, P2, P3 and the pore size distributions q1, q2, q3, for example, can be evaluated and determined.

[0074] Furthermore, using a Table 1 explained below, corresponding properties with regard to the porosities P1, P2, P3 of the first, second and third concrete block layers 2a, 2b, 2c are then summarized in tabular form for an exemplary embodiment of the present concrete block 1, wherein the data have been obtained via thin section microscopic evaluations (as described in Example 1).

Example 1: Thin Section Microscopic Examination and Determination of the Pore Proportions of the Samples

[0075] Thin section microscopic examinations are generally known to a person skilled in the art and were carried out in the present case in a known manner, wherein details of the examinations are described in greater detail below.

[0076] For the thin section microscopic examination, a sample of each concrete block layer 2a, 2b, 2c was prepared in the form of a polished thin section with a section thickness of approximately 25 m and a format of approximately 20 mm40 mm. For preparation, the samples were embedded in epoxy resin with a fluorescent dye (epodye). This fills most of the pores and makes them visible under the microscope due to the coloring of the epoxy resin.

[0077] The subsequent microscopic examinations were carried out according to Example 1 using a digital microscope unit (Keyence VHX-7000) with corresponding objectives for a 20 to 500 magnification. Microscopy was performed with linearly polarized light and subsequent false colour imaging. Images were captured using a high-resolution 4K camera (Keyence VHX-7100).

[0078] 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, i.e. as a quantitative determination of the respective total pore area proportions.

[0079] This determination was carried out using evaluation software with predetermined settings. All pores with a pore area A greater than 100 m2 were selected and recorded using color identification of the colored epoxy resin. According to the evaluation settings, pores in aggregates were removed manually and pores with incompletely colored filling were added manually. The number n of recorded pores (each with a pore area A greater than 100 m2) thus results from the evaluation in accordance with the specified evaluation settings.

TABLE-US-00001 TABLE 1 tabular summary of exemplary examination results Table 1: tabular summary of exemplary examination results Concrete block layer 2a 2b 2c Number n of pores 1922 305 323 detected Total area of the pores 57,098,052 80,041,579 34,929,925 [m.sup.2] Proportion of the pore 5.30 7.79 4.79 area [%] Maximum pore size 685,464 5,867,605 2,664,421 [m.sup.2] Mean pore size [m.sup.2] 29,707 262,431 108,142

[0080] As Table 1 clearly shows, the non-fines porous second 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 mean pore size.

[0081] In the example shown, the number n of pores in the first concrete block layer is significantly higher than 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 layer 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, wherein the pores of the third concrete block layer 2c have a significantly enlarged mean pore size than the pores of the first concrete block layer 2a.

[0082] 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 FIGS. 5a to 5c and in Table 1 for a preferred variant of the concrete block 1, the capillary system is set up in the concrete block 1, in particular in the third concrete block layer 2c, with a suction force in order to suck water or transport it via capillary action from the bedding layer of the substrate against gravity into the concrete block 1, namely into the second concrete block layer 2b, where the water can then be held or stored due to the porosity in order to be available for efficient evaporation.

[0083] The third concrete block layer 2c has a lower water permeability compared to the second concrete block layer 2b, which is significantly reduced in particular with regard to the gravity-induced water flow. In the present context, a water-permeable layer with low water permeability is understood to be a concrete block layer through which water can be transported or channeled, but with a time delay and/or with a mitigated or reduced, in particular significantly mitigated or reduced, flow rate compared to the second, water-permeable concrete block layer 2b.

[0084] With reference to FIGS. 3 and 4, the water transport in a surface covering 10 made of several concrete blocks 1 is illustrated once again. The surface covering 10 comprises a plurality of multi-layer concrete blocks 1 laid in combination on a bedding layer 3 of a substrate. Joints 5 are formed between adjacent concrete blocks 1 of the surface covering 10 and 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 substantially consists of a material mixture with a grain size of 0.1 mm to 5 mm.

[0085] The third concrete block layer 2c of the concrete blocks 1 has a capillary suction effect for drawing water from the underside of the concrete block 2.1 through the third concrete block layer 2c into the second concrete block layer 2b, namely in a first direction R1. Via this suction effect or capillary effect, water from the bedding layer 3 can be supplied 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 in order to promote evaporation V. The third concrete block layer 2c therefore has an irrigation effect for the second concrete block layer 2b.

[0086] The irrigation effect is particularly advantageous if, due to the capillary suction force of the third concrete block layer 2c, the first direction R1 running from the concrete block underside 2.1 towards the second concrete block layer 2b is greater than the second direction R2 running from the second concrete block layer 2b towards the concrete block underside 2.1.

[0087] The infiltration and absorption path for precipitation water, as indicated by the black simple arrows in FIG. 4, substantially reflects the condition in the event that water is present in excess due to incident rain. The rainwater hitting 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 rainwater can also be let through and channeled by it. Irrespective of this, at least a sufficient proportion of the percolating precipitation water moving in the direction of the bedding layer 3 passes from the joint material 6 into the porous second concrete block layer 2b, which is designed to absorb and store water particularly effectively due to its porosity and permeability. The porous second concrete block layer 2b absorbs the water here like a sponge, for example. 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 substrate, is delayed or reduced or inhibited and possibly even completely prevented. This delayed, possibly almost blocked water transport in the second direction R2 is indicated by dashed arrows in FIG. 4, as is the optional water transport through the first concrete block layer 2a.

[0088] Due to the special design and nature of the porosities P1, 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.

[0089] In FIG. 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 R1. This suction effect can ensure the water supply of the second concrete block layer 2b even in the absence of precipitation. The precipitation water absorbed and stored in the second concrete block layer 2b as well as the water replenished 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 maintained constantly and, in particular, effectively in this way.

LIST OF REFERENCE SIGNS

[0090] 1 concrete block [0091] 2 concrete block body [0092] 2a first concrete block layer [0093] 2b second concrete block layer [0094] 2c third concrete block layer [0095] 2.1 concrete block underside [0096] 2.2 concrete block top side [0097] 2.3, 2.4 concrete block sides [0098] 3 bedding layer [0099] 4 spacer lugs [0100] 5 joints [0101] 6 joint material [0102] 10 surface covering [0103] A pore size, pore area [0104] As layer thickness of the first concrete block layer [0105] Db layer thickness of the second concrete block layer [0106] Dc layer thickness of the third concrete block layer [0107] H total height of the concrete block [0108] LA longitudinal axis [0109] MHA center vertical axis [0110] n number of pores [0111] P1, P2, P3 first, second, third porosity [0112] q1, q2, q3 first, second, third pore size distribution [0113] R1, R2 first and second direction of water permeability [0114] V evaporation