DE29506826U1 - Building element made of concrete and natural stones - Google Patents

Description

DE 6847 * ,· .· , &idigr; i:.:.ßaterfta»walt

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Reinfried JFrhr. &ngr;. Schorlemer

Karthäuserstr. 5A 34117 Kassel Germany

Telephone (0561) 15335

(0561)780031

Fax/Telecopter (0561)780032

Willi Wachenfeld, 99974 Mühlhausen

Construction element made of concrete and natural stone

The invention relates to a component of the type specified in the preamble of claim 1.

For paving streets, paths, squares and pedestrian zones, for example, and for designing terraces, balconies, house entrances and steps, either concrete stone products, in particular cast stone products, or pure natural stone products, in particular slabs, are normally used. Although concrete stone products are inexpensive, they mostly have a monotonous, unattractive surface, even if they have been sandblasted and have a marble or granite facing. Natural stone products, on the other hand, are usually characterized by a beautiful-looking surface, but are comparatively expensive.

A compromise between the two types of product is the building elements of the type mentioned above, which are particularly well-known in the form of so-called sandwich panels. They consist of a relatively thick support, e.g. a concrete slab, which, depending on the application, has a thickness of 40 to 200 mm, for example, and a natural stone slab connected to it, e.g. 20 to 30 mm thick, which forms a visible surface of the building element. This makes the visible surface of the building element look like natural stone, while the requirements placed on the load-bearing properties

Requirements are essentially met by the concrete support. In this way it is possible to combine a beautiful appearance with comparatively low prices and at the same time significantly reduce the consumption of natural stone.

To bond the two parts together, adhesives made of cement/plastic compounds that are specifically designed for bonding concrete/natural stone are generally used. To improve adhesion, the adhesive is not only distributed over the interface between the two parts, but also filled in grooves that are worked into the underside of the natural stone slab intended to rest on the support, arranged lengthways or crossways and usually produced by milling.

A problem that has not yet been solved in the manufacture of such sandwich construction elements is that the grooves required to accommodate the adhesive and concrete also act as predetermined breaking zones for the natural stone slabs. When using particularly thin natural stone slabs, it has been observed that these break easily in the area of the grooves when subjected to stress. Tests have shown that in order to avoid this problem, either the groove depth must be so small that the connection does not last in the long term, especially when there are strong temperature fluctuations, or natural stone slabs must be used that are so thick that an optimal reduction in costs and natural stone consumption cannot be achieved.

The invention is therefore based on the object of designing the structural element of the type described at the outset in such a way that there is no risk of breakage even when using thin natural stone slabs on the one hand and sufficiently deep grooves for the connection on the other.

The characterising features of claim 1 serve to solve this problem. 30

Further advantageous features of the invention emerge from the subclaims.

The invention brings with it the surprising advantage that even when using

thin natural stone slabs down to approx. 10 mm and ring-shaped grooves with depths of approx. 5 mm, no breakage was observed and yet a permanently good connection was achieved between the carrier and the natural stone slab.

The invention is explained in more detail below in conjunction with the accompanying drawings using exemplary embodiments. They show:

Fig. 1 is a plan view of a component according to the invention in the form of a base plate; Fig. 2 is a section along the line Π-Π of Fig. 1;

Fig. 3 is a bottom view of a natural stone slab of the structural element according to Fig. 1;

Fig. 4 is a front view of a component according to the invention in the form of a stair step;

Fig. 5 is a section along the line V-V of Fig. 4;

Fig. 6 is a plan view of the component according to Fig. 4; 20

Fig. 7 is a front view of a building element according to the invention in the form of an angle wall part; and

Fig. 8 is a section along the line Vm-Vm of Fig. 7.

According to Fig. 1, a construction element according to the invention in the form of a floor slab contains a support 1 made of concrete, which here essentially consists of a plane-parallel slab with a thickness of e.g. 40 to 200 mm. The support 1 has a flat surface 2, on which a likewise flat underside 3 of a natural stone slab 4 rests, which is preferably also plane-parallel, but only has a thickness of e.g. 10 mm. The natural stone slab 4 is provided with circular ring-shaped grooves 5 worked into the underside 3. These are filled with a suitable adhesive, e.g.

an adhesive emulsion in the form of a cement/plastic compound that is specially designed for bonding concrete and natural stone, whereby the adhesive can harden in the air.

The width of the ring-shaped grooves 5, which are produced, for example, with a ring milling cutter, in the exemplary embodiment is 5 to 6 mm with an outer diameter of 50 to 60 mm. The distances between the centers of the ring grooves 5 from one another are preferably 80 to 150 mm, in particular 100 to 120 mm, but from the lateral edges of the natural stone slab 4 they are preferably at least 50 mm, in particular 60 to 80 mm. The groove depth is 5 mm.

Construction elements of this type are preferably manufactured in standard sizes (e.g. 400 mm x 400 mm). Depending on the thickness of the panels, they are suitable for paving streets, paths and squares or the like and, if the support 1 is sufficiently thick (e.g. 200 mm), they can also be driven over by motor vehicles, especially buses.

Furthermore, as shown in Figs. 1 to 3, the annular grooves 5 are preferably distributed uniformly over the entire underside 3, so that a permanently good adhesion to the carrier 1 is achieved everywhere.
20

The natural stone plate 4 can be made from any natural stone, in particular granite, quartzite, marble, limestone, sandstone or the like.

The invention provides the advantage that the building element can be manufactured more cheaply and with less natural stone while maintaining the same durability.

In the embodiment according to Fig. 4 to 6, a support 7 made of concrete is provided in the form of a stair step (block step). The support 7 has, in the usual way for stair steps, a visible upper and front surface 8 and 9, which, analogously to Fig. 1 to 3, are each covered with a natural stone slab 10 or 11, which has a large number of annular grooves 12 in its underside. Where the natural stone slabs 10 and 11 meet at the front, upper corner of the support 7, they can be provided with bevel cuts to form a miter joint 13.

In Fig. 7 and 8, a concrete support 15 is provided in the form of an angled wall part, which, analogous to Fig. 3 to 6, is covered on two flat surfaces with a natural stone slab 16 or 17. Here, too, ring-shaped grooves 18 are provided for the firm connection between the support 15 and the natural stone slabs 16 and 17, which border on the undersides of the natural stone slabs 16 and 17.

The construction elements are preferably manufactured by first providing the natural stone slabs with the ring-shaped grooves and then placing them with their undersides facing upwards in rubber molds. The undersides are then provided with an adhesive (e.g. the adhesive that can be mixed with water and is sold under the brand name "PCI-Pecihaft"), particularly in the area of the grooves, which is applied with a brush, for example, and then concrete is added, preferably with constant shaking so that the concrete also settles in the grooves. The finished construction elements are then left to dry in the air before they are removed from the molds.

According to a particularly preferred embodiment of the invention, the adhesive is the concrete itself, for example by using an extremely hard concrete (eg above 100 N/cm ² ) or by adding an additive to the concrete that increases the adhesive properties. A particularly preferred additive for these purposes is fine-grained silicon dioxide in microfine form (grain size eg predominantly smaller than 45 μ), as is marketed for example by Elkem GmbH in Düsseldorf under the brand name "Elkem Microsilicia".

The invention is not limited to the described embodiments, which can be modified in many ways. In particular, Fig. 4 to 8 show that the invention is applicable not only to plate-shaped building elements, but also to numerous other building elements. In addition, the supports 7 and 15 could be provided with steel reinforcements if additional strength requirements are required, e.g. when used as window or door lintel. Furthermore, it would be possible to produce connections of the type described between concrete supports and natural stone elements even if they lie on top of one another along a boundary surface that is curved or, in contrast to Fig. 5 and 8, runs along an interior angle. Finally, it goes without saying that

that the dimensions given are only preferred examples and the dimensions actually to be used depend on the circumstances in the individual case, in particular on the loads exerted on the natural stone slabs when installed.

Claims (6)

Expectations 1. Construction element with a support (1, 7, 15) made of concrete and having at least one surface (2, 8, 9) and at least one natural stone slab (4, 10, 11, 16, 17) which rests on the surface of the support (1, 7, 15) with an underside (3) having grooves (5, 12, 18) and is firmly connected to it by means of an adhesive filled into the grooves, characterized in that the grooves (5, 12, 18) are ring-shaped and are arranged distributed over the underside of the natural stone slab (4, 10, 11, 16, 17). 2. Component according to claim 1, characterized in that the annular grooves (5, 12, 18) are arranged with center distances of 80 to 150 mm. 3. Component according to claim 1 or 2, characterized in that the distances of the centres of the annular grooves (5, 12, 18) from the plate edges are at least 50 mm. 4. Component according to one of claims 1 to 3, characterized in that the annular grooves (5, 12, 18) have an outer diameter of 30 to 80 mm. 5. Component according to one of claims 1 to 4, characterized in that the groove depth is 5 to 6 mm. 6. Construction element according to one of claims 1 to 5, characterized in that the adhesive is concrete, preferably a concrete made high-strength by the addition of an additive.