Core-insulated pre-fabricated wall piece with connector pins

This invention relates to a pre-fabricated wall piece for the construction of buildings, comprising an inner wall and an outer wall made from concrete, connected to each other by means of reinforcements and with a cavity between both walls for subsequent filling with concrete, with the inner side of the outside wall facing the inner wall further comprising a thermal insulation layer.

It is known that for constructing walls of buildings in the basement as well as the living areas, double-wall elements can be used whose outer walls are connected to the inner walls with lattice-beams and that comprise a core insulation consisting of thermal insulation panels or insulation material applied in some other manner. These pre-fabricated wall pieces have the advantage that they can be produced at the factory as transportable parts and independent of weather conditions. Such pre-fabricated wall pieces can be made true to measure, are assembled at the construction site, and are filled, without gaps, with concrete or similar materials.

DE 198 23 387 describes a pre-fabricated wall piece where the outer wall and the inner wall are connected by means of spaced lattice beams. In order to provide thermal insulation, one or several layers of a porous insulating coating made of polyurethane foam are applied to the inner side of the outer wall. In order to prevent air humidity from causing the lattice beams to rust through over time, the beams are made from non-rusting material. Pre-fabricated wall piece elements made in this manner have the disadvantage that the lattice beams form massive heat bridges between the inner and outer wall, thereby allowing significant heat transfer.

The invention addresses this problem by proposing a pre-fabricated wall piece that offers a reduced heat transfer between the inner and outer wall due to fewer heat bridges, and is simple and economical to produce while being able to support high loads.

According to the invention, this problem is solved by a pre-fabricated wall piece with the characteristics given in claim 1. Other advantageous embodiments are described in the subclaims.

According to the invention, the reinforcement connecting the inner and the outer wall of the pre-fabricated wall piece proposed by the invention comprises U-shaped connector pins made of steel whose web is held in the outer wall. In addition, the pre-fabricated wall piece proposed by the invention comprises a lattice beam reinforcement that projects from the inner side of the inner wall facing the outer wall into a cavity between the inner and the outer wall that is to be filled with concrete on site. The connector pins are spaced in the concrete of the outer wall, and their front tips are embedded in the concrete of the inner wall. They serve for the horizontal positioning of the outer wall relative to the inner wall. In order to ensure a sufficient transfer of tensile forces, the front tips of the connector pins have a wavy shape. In addition to the inner wall of the pre-fabricated wall piece, this makes it possible to give the outer wall load-bearing capacities, too, so that it can also serve without restrictions for load transfer purposes. For example, it now becomes possible to place the outer wall of pre-fabricated houses directly above the outer wall of the pre-fabricated wall piece forming the basement wall, thereby transferring the load of the outer wall of the pre-fabricated house directly to the outer wall of the pre-fabricated wall piece proposed by the invention. Preferably, the connector pins connecting the outer and the inner wall are made of a non-rusting material like stainless steel (V2A, V4A) or hot-galvanized steel in order to prevent them from rusting through over time. The distance the lattice-beam reinforcement projects from the inner wall projects into the cavity between the inner wall and the outer wall may vary. It may end before reaching the insulating layer, it may end at this layer, or may also enter into this layer for a short distance. When the cavity is filled with concrete, it is embedded in the concrete and provides a shear-proof connection of the cured concrete and the inner wall of the pre-fabricated wall piece.

Preferably, the lattice-beam reinforcement embedded in the concrete of the inner wall extends all the way to the insulating layer of the outer wall. The lattice beams are arranged evenly spaced over the length of the pre-fabricated wall piece, reaching from the lower end to the upper end of the pre-fabricated wall piece. The lattice beams do not penetrate the insulating layer of the outer wall, and are not connected with the outer wall. This has the advantage that there is no heat transfer via the lattice beams between the inner and the outer wall, which improves the thermal insulation. For support, the outer wall of the pre-fabricated wall piece rests on a foundation (concrete support, bed of mortar) because the connection of the outer wall and the inner wall via the connector pins is not sufficiently shear-proof. This makes it possible to transfer vertical loads to the outer wall. The lattice-beam reinforcement may consist of steel without corrosion protection.

Preferably, the upper end of the outer wall comprises a row of connector pins serving as connection reinforcement, with the free ends of the connector pins projecting into the space of a joint with a ceiling element. The wavy tips of the connector pins augment the reinforcement of the ceiling element resting on the inner wall; after the ceiling element has been filled with concrete, they provide a shear-proof connection of the outer wall with the ceiling element.

As shown in FIG. 1 and FIG. 2, the embodiment of the core-insulated pre-fabricated wall piece 1 proposed by the invention consists of two factory-made walls 3, 4 that are spaced and connected by connector pins 2 made of stainless steel. Between the outer wall 3 and the inner wall 4, there is a cavity 5 that is filled with concrete 19 at the construction site. A thermal insulation layer 8 made of expanded polyurethane or polystyrene is applied to the inner side 6 of the outer wall 3. As installed at the factory, the connector pins 2 serve to accept the horizontal forces from the fresh-concrete pressure of the on-site concrete filling 19, and, in completed condition, for the horizontal positioning of the outer wall 3 relative to the inner wall 4. A shear-proof connection between the inner wall 4 and the on-site concrete core is established by the lattice beams 9. Ex factory, the lattice beams 9 are embedded in the inner wall 4 and extend all the way to the thermal insulation layer 8. The lattice beams 9 extend from the lower end 10 to the upper end 11 of the pre-fabricated wall piece 1 and are arranged with a spacing of ≦62.5 cm over the length of the inner wall 4. However, unlike conventional pre-fabricated wall pieces with core insulation, the lattice beams 9 do not connect the outer wall 3 with the inner wall 4 of the pre-fabricated wall piece 1, and therefore do not assume a stabilizing function for the outer wall 3 of the pre-fabricated wall piece 1. Consequently, the outer wall 3 rests on a concrete support 12 placed on a bottom 13. At the upper end 11 of the pre-fabricated wall piece 1, transportation lugs 14 connected with the outer wall 3 and the inner wall 4 are provided. The transportation lugs 14 form a shear-proof connection between the inner wall 4 and the outer wall 3 that is only effective during transportation and assembly and prevents the walls 3, 4 from shifting relative to each other. When the cavity 5 of the pre-fabricated wall piece 1 is filled with concrete 19 on site, the transportation lugs 14 may be embedded in place. The outer wall 3 is self-bearing and has a wall thickness of approximately 8 cm. In this design, the inner wall 4 has a thickness of approximately 6 cm. Depending on the desired thermal insulation effect, the thermal insulation layer 8 is between 2 and 12 cm thick and the cavity 5 is 10 cm wide in order to ensure the sufficient stability of the pre-fabricated wall piece 1. The connector pins 2 are evenly distributed over the surface of the pre-fabricated wall piece 1, and spaced approximately 50 to 60 cm from each other. They are U-shaped and have wavy tips. The webs of the connector pins 2 are embedded in the outer wall 3, and their wavy tips are embedded in the inner wall 4, penetrating the thermal insulation layer 8. Typically, the connector pins 2 have a diameter of 5 mm. In order to stabilize the pre-fabricated wall piece 1, connector pins 2 with a diameter of 8 mm can be used for the lowermost row of connector pins 15. At the upper end 11 of the pre-fabricated wall piece 1, an uppermost row of connector pins 16 is provided as connecting reinforcement with a ceiling element 17. The webs of the connector pins 2 of the uppermost row of connector pins 16 are embedded in the outer wall 4, with their free ends projecting into the space of a joint 20 with the ceiling element 17. The row of connector pins 16 is embedded when the ceiling element 17 is filled with on-site concrete 18 and thereby establishes a tension-proof and shear-proof connection of the outer wall 3 with the ceiling element 17.

The manufacture of the pre-fabricated wall piece 1 described above proceeds as follows: after the concrete of the outer wall 3 has been placed on a metal plate or similar device, with simultaneous embedding of the connector pins 2, the thermal insulation layer 8 is applied to the inner side 6 of the outer wall 3 by means of foaming or the insertion of thermal insulation panels. After the foam has cured, or after the thermal insulation panels of the thermal insulation layer 8 have been inserted, the entire part is turned and, for manufacturing the inner wall 4, immersed with the free tips of the connector pins 2 that protrude from the thermal insulation layer 8 into a bed of concrete located on a metal plate or similar device, with lattice beams 9 inserted into said bed of concrete, which is then vibrated and allowed to cure. The placement of concrete for the outer wall 3 and the inner wall 4 on a metal plate or similar device for the purpose of later detachment is done in conventional fashion, thereby ensuring a smooth outer surface of the outer wall 3 as well as of the inner wall 4 that requires no further processing to achieve the desired surface quality of the panels.