EP1582628B1 - Method for producing a porous artificial stone slab - Google Patents

Abstract

A lower layer (30) comprising a hardenable mixture including particles obtained from broken natural stone, with a particle size greater than 0.5 mm. The lower layer includes pores. An upper layer (20) comprises a second hardenable mixture of particles obtained from broken natural stone, with a precious surface such as granite, marble or porphyry. The surface layer includes pores, and is at least 8 mm thick, being thinner than the lower layer. After hardening the surface of the upper layer is sandblasted so that the particles are clearly revealed.

Description

The invention relates to a method for producing a water-permeable artificial stone slab with at least two layers, namely a lower layer of a first hardenable mixture consisting essentially of grains, which are obtained from broken natural stones and cement, said first layer having pores and a superficial layer consisting essentially of a second hardenable mixture of grains obtained from crushed natural stones and 150-450 kg of cement, the superficial layer having pores and being thinner than the lower layer and the two layers joined together.

Out DE 102 18 634 For example, a method for producing an artificial stone is known. In a mold, first a ground fresh first layer of a first curable mixture is introduced. It consists of grains obtained from broken natural stones with a grain size of 1 to 16 mm and 150 to 450 kg of cement per cubic meter of grain. This first layer is compacted in a press by applying a defined force within the mold on the short side. On the still fresh first layer, a fresh, moist, second layer of a second curable mixture is applied. It consists of grains obtained from crushed natural stones whose grain size exceeds the grain size of the grains of the first layer, preferably the grain size is in the range of 4 to 9 mm, and 150-450 kg of cement per cubic meter of grains. Also, the second layer and thus indirectly the first layer is compacted by applying a defined force within the mold. The process can also be carried out in a different order by first introducing the second layer into the mold and then the first layer. The first layer is a superficial layer, the second layer is thicker than the first layer.

Out DE 39 09 169 A1 is a water-permeable, natural-colored paving element in the form of plates, paving stones, composite stones and the like, which can be used to pave sidewalks, paths, etc.

In these artificial stone slabs, a high permeability to water is achieved at least in the upper layer. This is because the top layer has a larger portion of pores that are contiguous and continuous. As a result, a strong supply of water is easily coped with. The surface of the superficial layer remains moist after being fed with water, but it never accumulates water on this surface. There are no puddles. This prevents you from slipping. The surface also has a granular structure, so it is not smooth.

Usually, the pore volume increases from the superficial layer to the lower layer. The lower layer thus has more pore volume than the superficial layer. As a result, water is drained rapidly downwards and prevents clogging of the pore system.

A disadvantage of the previously known artificial stone, in particular those according to DE 102 18 634 A1 , the optical quality of the surface is the superficial layer. Even if the superficial layer is introduced into a mold as a second layer, due to the mixing process of the curable mixture of this layer, the grains are coated with cement paste, which is also necessary for the inner bond but interferes with the surface. Now, however, the artificial stone slab is just for applications with aesthetic demands, for example in swimming pools, terraces and the like. In these applications, a great value is placed on a visually appealing surface.

Out DE 198 08 494 A1 For example, a method of making an artificial paving stone having a concrete facing layer is known, and the compacted concrete facing layer is brushed dry on its surface. The dry brushing results in an uneven removal of the material from the facing surface and a certain, irregular structuring is achieved. A water permeability of the artificial paving stone is not described.

Out DE 100 54 818 A1 is a method for producing concrete floor slabs known. The top of the bottom plates is surface treated after curing of the concrete, for example by grinding to achieve the smoothest possible surface or by a ball treatment to achieve a defined roughened surface. A water permeability of the bottom plate is not specified

Out DE 37 02 313 C1 is a method for producing a concrete paving stone or a concrete slab known in the concrete is stored in split. After the pressing process, the concrete is washed in not yet hardened state from the surface of the stone or the plate between the split grains in the desired depth. After hardening of the concrete, the sharp edges of the split grains protruding on the surfaces of the stone or plate are removed with the aid of a sandblast blower. A water permeability is not specified.

The invention has set itself the task of developing the method for producing the previously known water-permeable artificial stone slab to the effect that the artificial stone slab has an aesthetically pleasing surface, in particular has a high quality.

This object is achieved by the features of claim 1.

In the method according to claim 1, the surface of the surface layer after curing is subjected to a sandblasting process. In this case, special grains are used, namely those that have no chance due to their size to get into the pores. The grains therefore remain on the surface, they can not get into the pore system. On the surface, however, the grains cause the grains lying on the surface to have a particularly nice, cleaned surface. Any cement haze is removed by the jet grains. The grains also polish the surface, resulting in an aesthetically beautiful, even design the surface is coming.

Particularly favorable is the use of white cement, which looks much better aesthetically, as the commonly used gray cement. Due to the white cement, the superficial grains are better able to stand out of the environment. In the finished stone, the cement areas located between the grains are slightly deeper than the general surface of the grains. In other words, the crests of the grains form the outer surface and the cement bridges are slightly behind. The pores are also visible between the grains. Due to the grains of the grains, the grains, as far as they are on the surface, are partially exposed. One achieves a similar result, as it is already known in washed concrete. In contrast to washed concrete, in which the superficial grains are exposed and the cement veil is removed by wiping and rinsing with water, but only worked dry. This prevents the pores from clogging due to the mixture of cement and water.

It has proven to be very advantageous to take jet grains which are not comminuted by the blasting process. For example, one knows of grains of sand, which are typically used for sandblasting, that they are gradually crushed, so when hitting split into pieces. Then there is the danger that crushed sand is introduced into the pores. If one uses as a ray grains but resistant material, such as stainless steel balls, as they are commercially available in the range 0.5 to 1 mm, you can use this repeatedly in processing, the grains generally do not burst, but they remain largely intact. As a result, no portion of the jet grains is brought into the pores of the superficial layer. Offered are stainless steel balls and comparable blasting agents such as cast steel balls, metal balls, steel pieces, of z. Würth ironworks, Bad Friedenshall, under ROBE stainless steel shot blasting and FILGRA blasting wire grain.

By selecting the beam direction of the machining process can be influenced. With flatter beam direction, so flatter impact of the beam grains, the surface is better uniformed. At steeper angles, you avoid shadows and it is possible to create special effects. At shallow beam angles, it has proven advantageous to rotate the stone slowly during machining around a vertical axis. This avoids shadows.

It has proven to be preferable to sand blast overhead, so to let the surface show down. As a result, the removal, which form the jet grains falls down and does not lie on the surface of the superficial layer.

Preferably, the superficial layer is 10 to 15 mm thick. Since it is made of precious stones, it is only made as thick as absolutely necessary. This results alone from cost considerations assumes the strength, in particular the static strength, receives the artificial stone plate substantially through the lower layer. For these grains can be used as inexpensive as possible, it can also be used normal, gray cement. The lower layer is, once the plate is laid, no longer visible.

The order of production of the two layers is arbitrary. It can be started with the superficial position and be piled up on this, the lower layer, as long as still connection between these two layers is possible. But it can also be worked the other way round, so first the lower layer are placed in a mold and applied to this the superficial layer, again as long as still a connection of the two layers is possible.

It has proved to be advantageous to sand the surface of the superficial layer at least somewhat. Essentially, only the most prominent parts of those grains that lie in the surface, are ground down slightly.

Fig. 1:

einen Querschnitt durch ein kleines Stück einer Kunststeinplatte nach der Erfindung,

Fig. 2:

eine Darstellung wie in Figur 1, jedoch mit teilweise plan angeschliffener Oberfläche und

Fig. 3:

eine Darstellung wie in Figur 1, nun ist zusätzlich der Vorgang des Sand- bzw. Körnerstrahlens mit eingezeichnet.

Further advantages and features of the invention will become apparent from the other claims and the following description not limiting to understand embodiments, which are described below with reference to the accompanying drawings. In the drawing show:

Fig. 1:

a cross section through a small piece of an artificial stone slab according to the invention,

Fig. 2:

a representation as in Figure 1, but with partially planely ground surface and

3:

a representation as in Figure 1, now also the process of sand or grains is shown with.

The artificial stone slab invention consists of grains of different types, which are obtained from natural stones. Grain mixtures can be used. The grains are extracted from mineral material and are connected by cement. Between the grains a pore system remains free. The pores are continuous and have a considerable volume, for example 10%, preferably 30%, possibly even 40 to 50% of the total volume of the artificial stone.

A surface layer 20 of the artificial stone has a surface 22 accessible in the installed state of the stone. The surface layer 20 is formed from a first hardenable mixture. This consists essentially of grains 24 whose grain size is in the range of 1.5 to 10 mm, preferably 2 to 6 mm grain dimensions. The fine and fines should be removed as much as possible, it is undesirable. Typical material for the grains is granite, basalt, porphyry, marble and the like. The curable mixture still contains white cement, the proportion is between 180 and 300 kg per cubic meter of granular material. By using white cement, surface 22 is optically more beautiful than achievable with conventional gray cement. The cement bridges are shown in the figures.

The artificial stone is at least two-layered. A lower layer 30 is intimately connected to the superficial layer 20, in particular freshly worked in fresh, so that the cement bond 38 and the compound of the layers 20, 30 secures. The lower layer 30 consists of a curable mixture. This second mixture is composed of grains 34 and cement. Normal, gray cement is used. The grain size of the grains 34 is always in the range above the grain size of the grains 24 of the surface layer 20, e.g. the grain size is in the range of 3 to 12 mm, preferably 3 to 8 mm grain dimensions. Preferably, the grain size of the lower layer grains is at least twice that of the grains 24 of the surface layer 20. Larger factors, e.g. triple and quadruple, are possible.

Between the grains of both layers 20, 30 are pores 26, 36. These form a pore system which is interconnected. This also applies to the connection region of both layers 20,30. Overall, the pore volume of the artificial stone should be above 10% by volume, preferably above 15% by volume.

The pores 36 of the lower layer 30 are generally larger than the pores 26 of the surface layer 20. Also, it is desirable that the total pore volume of the lower layer 30 is greater than that of the surface layer 20. This penetrates dirt particles better forwarded down. It is achieved a good water permeability and water drainage.

For the lower layer 30 inexpensive grains 34 can be used, it can be used a grain mixture. The grains 34 of the lower layer 30 are not visible in the installed state, with these grains 34, therefore, it essentially depends on sufficient strength, availability and price.

The thickness of the surface layer 20 is chosen as small as possible in order to use the expensive material, namely both the white cement and the high-quality stone, as favorably as possible. But it must be ensured that the superficial layer 20 is opaque, so the stones of the lower layer are not visible. Also, the manufacturing process must be such that the stones of the lower layer can not penetrate into the region of the surface layer 20, so remain invisible.

In Figure 2, the surface 22 is ground slightly flat. This plan grinding can also train more intensified. The surface finish makes the surface more valuable, removing random tips of grains that protrude upwards.

FIG. 3 shows the method of sandblasting. From a blasting device 40 exits a compressed air flow, the jet grains 42 promotes. The grains are stainless steel balls with a diameter in the range 0.5 to 1 mm. The jet emerging from the jet device is essentially bundled. But it is also possible to use relatively broad beam bundles, eg with an opening angle of 30 °. The beam strikes the surface 22 with a main direction 44. This main direction can be steep, but it can also be chosen flat, as shown in Figure 3. In Figure 3, the angle is about 30 °, which includes the main direction 44 with the surface 22. At a shallower angle, the grains 24 that lie in the surface are ground a little flat. When the direction of the sandblast is more steeply set, the individual grains 24, as far as they are in the surface, emerge more clearly, they are practically worked out. It is understood that the sandblasting is only so far driven that reaches the desired optical quality of the surface 22 becomes. Under no circumstances should sandblasting be carried out so far that grains 24 are dissolved out of the surface.

The method for producing the artificial stone may be corresponding to the teaching and the already mentioned DE 102 18 634 A1 be carried out, so applying pressure to the individual layers 20, 30. However, it can also be carried out without pressure. In general, a shape is used. The shape may be square, hexagonal or the like, generally the cast stone plate may have any shape reasonably suitable for installation. It can also quite irregular shapes are used, if one wishes a certain irregularity and proximity to the natural stone plate in the finished image of laid panels.

For the superficial layer 20 are particularly flat, ie platelet-shaped grains. They can be introduced so that they are substantially parallel to the surface 22. The pore geometry that sets in is beneficial for draining polluted water.

Usually 20 grains of a kind, so for example a particular marble used for the superficial layer. But it is possible to use grain mixtures.

The artificial stone is suitable for the inserts, as they are also in the DE 102 18 634 are called. The entire disclosure content of this document is hereby included in the disclosure of the present application.

As can be seen from FIG. 3, sandblasting is done overhead. As a result, dust that occurs during sandblasting falls down. In any case, it does not remain on the surface and therefore does not have to be removed later. If a certain amount of dust remains, it is preferably sucked off, in particular with a vacuum cleaner.

It is possible to blow air through the stone during sandblasting from behind, as indicated by the arrows 46 in FIG. As a result, dirt particles are positively moved away from the surface and torn away.

Claims (9)

1. A method of manufacturing a water permeable artificial stone slab with at least two layers, involving the following steps:

   - manufacturing a lower layer made from a first curable mixture consisting substantially of grains (34) obtained from broken natural stone and having a grain size of more than 0.5 mm, and from 150 - 450 kg, preferably from 180 - 300 kg, cement per cubic meter grains, said lower layer (30) having pores (36) and

   - manufacturing a superficial layer (20) that substantially consists of a second curable mixture of grains (24) obtained from broken natural stone, having a grain size of more than 0.5 mm and exhibiting an aesthetic, valuable surface (22) such as granite, marble or porphyry, and from 150 - 450 kg, preferably from 180 - 300 kg, white cement per cubic meter grains, said superficial layer (20) having pores (26), being at least 8 mm thick and thinner than the lower layer (30) and

   - manufacturing occurring so that the two layers (20, 30) are connected together,

   - the superficial layer (20) is left to cure and the surface (22) of this superficial layer (20) is sandblasted with blast grains (42) so that the grains (24) of the superficial layer (20) lying on the surface (22) appear clearly, with the cement veil being more specifically removed, the blast grains (42) used having dimensions large enough for preventing said blast grains (42) from penetrating into the pores (26) of the superficial layer (20).
2. The method as set forth in claim 1, characterized in that the superficial layer (20) is made 10 to 15 mm thick.
3. The method as set forth in claim 1, characterized in that blast grains (42) are used that are at least twice as large as the largest pores (26) of the superficial layer (20).
4. The method as set forth in claim 1, characterized in that blast grains (42) are used that are substantially spherical and that their diameter ranges from 0.5 through 1 mm, preferably that the blast grains (42) are stainless steel balls.
5. The method as set forth in claim 1, characterized in that sandblasting with the blast grains (42) occurs with compressed air and without any water added.
6. The method as set forth in claim 1, characterized in that, during sandblasting, the blast grains (42) strike the surface (22) of the superficial layer (20) at a flat angle, more specifically at an angle ranging from 10 to 50°, measured from the plane of the superficial layer (20).
7. The method as set forth in claim 1, characterized in that, in average, the pores (36) of the lower layer (30) are made larger than the pores (26) of the superficial layer (20).
8. The method as set forth in claim 1, characterized in that the superficial layer (20) is ground so that the grains (24) located on the surface (22) exhibit a polished face.
9. The method as set forth in claim 1, characterized in that the grains (24) of the superficial layer (20) are in average smaller than the grains (34) of the lower layer (30).

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