WO2000032889A1

WO2000032889A1 - Method for producing an at least two-layered external wall element and external wall element produced using said method

Info

Publication number: WO2000032889A1
Application number: PCT/EP1999/009221
Authority: WO
Inventors: Friedrich Romberger
Original assignee: Walter Bau-Aktiengesellschaft; Romberger Gmbh
Priority date: 1998-11-27
Filing date: 1999-11-26
Publication date: 2000-06-08
Also published as: AU1777900A; EP1133606A1; DE19854884A1

Abstract

The invention relates to a method for producing an at least two-layered external wall element (1) for a building, comprising the following steps: introducing pourable light concrete into a form in order to produce a support layer (3); applying pourable insulating layer material onto the unhardened support layer (3) in order to produce an insulating layer (4) which is integrally connected to the support layer (3); evening out the surface of the insulating layer material and hardening. The insulating layer material is produced by mixing an expanded glass granulate (41) with a cement matrix. According to the invention, fine-grain particles (42) are also added while the insulating material is being mixed. An external wall element (1) produced according to this method has the support layer (3) consisting of light concrete and the insulating layer that is integrally connected to the support layer (3), containing the expanded glass granulate (41) and fine-grain particles (42). This results in a series production-compatible external wall element (1) with high quality surfaces, since the fine-grain particles (42) serve as 'lubricants' for reducing the considerable inner friction that occurs between the expanded glass particles (41).

Description

description

Method for producing an at least two-layer outer wall element and outer wall element produced thereby

The invention relates to a method for producing an at least two-layer outer wall element for a building according to the preamble of claim 1. Furthermore, the invention relates to an outer wall element according to the preamble of claim 11.

Such an outer wall element is known for example from DE 195 42 315 AI. This has a statically loadable support layer, which is facing the inside of the building, and a thermal insulation layer, which is applied to the supporting position, facing the outside of the wall. The support layer is made of a statically resilient concrete material. The thermal insulation layer consists of lightweight concrete, which has light aggregate particles that are bound with a binder matrix. The light aggregate particles can be expanded glass granulate particles.

Such a wall element can be used as an industrially prefabricated prefabricated outer wall in plate form both for industrial buildings and in private residential construction. Here, the outer wall element must meet the conflicting requirements with regard to good thermal insulation properties and sufficient static load-bearing capacity.

To produce this known outer wall element, a layer of fine mortar serving as interior plaster is applied to a molding table with a smooth bottom and formwork edges that extend laterally. Then the concrete for the supporting layer is applied in the statically desired thickness and possibly pre-compacted by shaking or pounding. Immediately afterwards, the thermal insulation layer is applied until the desired total thickness of the wall element is reached. The insulating concrete used for the thermal insulation layer is to be leveled at the top by a peeling process. If necessary, this layer can also be preloaded beforehand by the action of vibration or the like. be sealed. In addition, it is possible to apply a cover layer to the surface of the thermal insulation layer as an outside closure of the wall element.

With such a wall element, good thermal insulation is made possible with good static load-bearing capacity. However, there were considerable problems during processing, since the applied thermal insulation layer is very difficult to level. Here, the insulation material proved to be very bulky, so that even with careful processing hardly any really flat outer surfaces were possible. The resulting uneven outer wall surface is particularly disadvantageous if it is not covered or is only covered with a thin-layer finishing coat. In particular, no constant surface quality is possible in series production in the known method.

Due to the very low dry bulk density of the thermal barrier layer of this known wall element, during handling, e.g. when stripping, transporting, positioning etc., there is also the risk of damage. For example, corner and edge areas of the thermal insulation layer can become damaged by breaking off parts, which can e.g. result in dirty connection points to neighboring elements. This worsens the insulation properties in this area and requires reworking on the construction site.

Another disadvantage of this known outer wall element is that relatively thick thermal insulation layers are required to enable good thermal insulation properties overall. Furthermore, the thermal insulation layer cannot make any contribution to the static load-bearing capacity of the wall element.

The invention is therefore based on the object of demonstrating a method for producing a multilayer outer wall element which is also suitable for the series production of such outer wall elements with good surface quality. Furthermore, an improved outer wall element is to be created with regard to the thermal insulation properties and / or the mechanical resistance of the thermal insulation layer.

This object is achieved by a method according to the features of claim 1. The method according to the invention provides for pouring a pourable lightweight concrete into a formwork to form a structurally resilient base layer of the outer wall element. Then a pourable insulating layer material is applied to the not yet hardened base layer, which has expanded glass granulate that is bound with a cement matrix. The exposed top of the insulation layer material is finally smoothed and leveled before the outer wall element can dry or harden. The resulting outer wall element thus represents an integral composite body.

The advantage here is that the insulating layer material according to the present invention can be smoothed particularly well, since it is also admixed with fine-grained particles. Apparently, these particles act as a kind of lubricant, through which the high internal friction between the glass particles can be reduced. According to the invention, it was recognized here that these frictional forces make it considerably more difficult for the insulating layer material to spread, and that such fine-grained particles can remedy the situation. This makes it possible for the first time to produce a good and uniform surface structure of the insulation layer material in a reliable and repeatable manner.

Therefore, for the first time, the method according to the invention can also be used to produce a multilayer outer wall element with very good insulation and structural properties.

Another advantage is that such fine-grained particles are generally available and known methods can be used to introduce them.

Another mechanism of action between the fine-grained particles and the expanded glass granules or the cement matrix is to be seen according to the invention in that these fine particles fill cavities between the coarser glass particles and thereby ensure a better distribution of the binder, that is to say the cement matrix. This enables a higher strength to be achieved, since the cement matrix, which is thus better distributed, creates a more stable “framework” in the insulation layer, without the need for a larger amount of cement matrix. If this should be desired it can be improved due to the use of the particles if this should be desired, due to the improved mixing of the components by means of the particles, more binders can also be added in order to further improve the mechanical resistance of the insulation layer. In particular, however, it is also possible to achieve good mechanical resistance with a relatively small amount of binding agent, as a result of which a low dry bulk density and therefore an improved insulation effect can be achieved.

It is also important here that the fine-grained particles fill the cavities between the coarser glass particles and thus better close the cold bridges present here. In addition, the particles themselves can have an insulating effect, so that the functionality of the insulating layer is further increased.

The outer wall element designed in this way therefore has a higher overall strength and / or better insulating properties.

The method according to the invention thus allows a simplified production of an outer wall element, which also has improved material properties.

Another advantage of the outer wall element according to the invention is that very good thermal insulation properties can be achieved with small wall thicknesses. In addition, the wall system is predominantly mineral and therefore easy to recycle.

With the manufacturing method according to the invention, the use of prefabricated components, for example in private residential construction, is therefore also interesting, since these can be produced more reliably and more cost-effectively.

Advantageous developments of the invention result from the features of the subclaims.

Due to the fact that expanded polystyrene is added as a particle, the thermal insulation properties of the outer wall element produced can be further increased, since these themselves have a particularly good thermal insulation effect exhibit. In addition, polystyrene particles or beads are readily available on the market and are offered at low cost.

It is a further advantage if the added particles have a grain size of approx. 1 mm. This size has proven to be particularly advantageous in practical tests, in order to be able to interact well with the individual glass particles to reduce the internal friction and at the same time to improve the thermal insulation properties. Furthermore, the particles settle well in the cavities between the expanded glass particles. This measure represents an average, the main part of this fraction should have a grain size of 1 mm.

It is advantageous if the particles are mixed in a small amount, in particular 15-20% of the volume of the material. Here it has been shown according to the invention that this amount is already sufficient to be able to effectively reduce the internal friction between the glass particles. In addition, the individual particles are then essentially only deposited in a few spaces between the larger glass particles, without forming their own layer areas and thus significantly influencing the mechanical properties of the insulation layer. Furthermore, the expenditure in terms of device technology for carrying out the method is also reduced due to the small amount of particles added.

If the added particles have a rough surface, the binder can be distributed even better within the thermal barrier coating due to the adhesion to the surface of the particles. The risk of segregation of the components can also be reduced. This aspect is particularly important in the case of larger differences in the bulk density of the components. This results in even better material properties with regard to the static load capacity.

Because the lightweight concrete for forming the base layer preferably has a pore structure and is produced by mixing expanded clay particles with a cement matrix, the base layer can also contribute to improved thermal insulation due to the special properties of the expanded clay. Lightweight concrete with a low bulk density can still be good static properties are provided. The total weight of the outer wall element produced by the method can thus be further reduced with better insulation properties.

If the cement matrix is foamed, an improved filling of the voids between the expanded clay particles or the expanded glass particles can be achieved. In particular, because of the better distribution of the cement matrix in the batch by means of the fine-grained particles, it is possible to foam the cement matrix to a lesser extent than is customary in the prior art, as a result of which a higher mechanical resistance of the insulation layer can be achieved with the same amount of cement matrix. In addition, it is advantageous if a foaming agent for foaming the cement for the base layer and / or for the insulation layer is based on the basic materials hemoglobin and / or cellulose. These raw materials can be metered in a simple and precise manner, which is particularly advantageous because the cement paste is preferably only foamed up to such an extent that the remaining free spaces in the batch are filled up. This is achieved by the air pores that form in the cement paste, which ensure even better mixing in the mixing device. This further improves the properties of the outer wall element produced according to the invention, in particular an improved homogeneity in the composite body being achievable. In addition, these raw materials are biological in nature.

It is a further advantage if zinc sterates are added to the insulation layer material, since the insulation layer can thereby be made water-repellent. This is particularly important because the insulation layer often comes to lie freely on the outside of the outer wall element and thus on the outside

May be exposed to weather conditions.

By adding glass or plastic fibers to the insulation layer material, cracks in the insulation layer can be avoided even better. The mechanical strength of the outer wall element against external influences also increases.

If the mixing of the insulation layer material by a mixing device that produces high internal shear forces, and in particular by a double wavy trough mixer is carried out, the foaming agents can come into effect better during the mixing process. This enables even better mixing to be achieved and an outer wall element with even more homogeneous individual layers can be produced.

According to a further aspect of the present invention, an outer wall element is provided with the features of claim 11.

The outer wall element according to the invention is characterized by a particularly good outer wall surface with outstanding flatness. In addition, the fine-grained particles arranged in the insulation layer promote the thermal insulation properties. Since the particles also ensure better mixing and distribution of the cement matrix in the expanded glass granulate, better mechanical resistance can also be achieved here.

With regard to further aspects and advantageous developments of the outer wall element according to the invention from the features of the further subclaims, reference is made to the above statements relating to the method according to the invention.

The invention is explained in more detail below in exemplary embodiments with reference to the figures of the drawing. It shows:

1 shows a schematically held cross section through an outer wall element according to the invention; and

Fig. 2 shows a vertical section through an outer wall of a building with outer wall elements according to the invention.

As shown in Fig. 1, an outer wall element 1 in this

Embodiment a four-layer structure. An interior plaster layer 2 is present towards the interior of a building. This is followed by a base layer 3, which is provided on the outside with an insulation layer 4 and finally with an outer plaster layer 5. The interior plaster layer 2 is designed in such a way that it offers a surface that is as non-porous as possible in order to be able to serve as a base for a wall paint, wallpaper, etc.

The base layer 3 is designed as a lightweight concrete layer and has a structure with a high pore structure. Expanded clay particles are used here, as are known for example under the brand name "Liapor". The expanded clay particles 31 have a fraction 4/8 mm. They are bound by a cement matrix, which is foamed during manufacture.

The insulation layer 4 has expanded glass particles 41, as are known for example under the brand name "Liaver ^® ". The expanded glass granulate is used in the 2-4 mm fraction. The insulation layer 4 has an aggregate structure. Polystyrene particles 42 are scattered in free spaces between the expanded glass particles 41. The polystyrene particles 42 have a grain size of 1 mm and have a relatively rough surface. The expanded glass particles 41 and the polystyrene particles 42 are bound with a cement matrix.

The method of manufacturing the layer structure of the outer wall element 1 is explained in more detail below.

A formwork table on which the formwork edges encompassing the sides and any cutouts, for example for doors or windows, are arranged as formwork for the formation of the outer wall element 1.

In the present exemplary embodiment, the interior plaster layer 2 is formed integrally with the base layer 3 and the insulation layer 4. For this purpose, the interior plaster material is sprayed onto the formlining in the intended thickness of 10 mm, for example, and then compacted on a vibrating table. This enables the surface of the interior plaster on the formwork side to be as free from pores as possible.

Furthermore, the material of the interior plaster is chosen so that high early strengths are guaranteed in order to enable the wall parts to be stripped as free of damage as possible, for example ten hours after production. To- the compacted plaster material has a high level of stability so that it is not shifted or damaged when the base layer concrete is poured.

An interior plaster based on lime and cement can be used here. Lime sand and mineral light aggregates such as Perlite, as well as additives to improve processing and to regulate the setting time are provided as additives. This means that the interior plaster can basically be processed on conventional plastering machines. A specific example of a suitable interior plaster has the following material properties:

Fresh mortar bulk density approx. 1,550 g / dm ³

Dry bulk density approx. 1,250 g / dm ³

Bending tensile strength approx.1.5 N / mm ² Compressive strength approx.3.5 N / mm ²

Modulus of elasticity 3500 N / mm ²

Thermal conductivity coefficient 0.4 W / (mK) water vapor diffusion resistance coefficient approx. 20.

Subsequently, the base layer 3 made of lightweight concrete with a heap-porous structure is applied to the interior plaster layer in the formwork. Here, the cemented aggregate results in a particularly low bulk density, the volume of the stroff volume being approximately 650 1 / m ³ . The material for the base layer 3 is mixed beforehand, the expanded clay particles 31 being bound with a foamed cement matrix. An agent based on the two basic materials hemoglobin and cellulose is used as foam pore generator. The foam pore generator is metered in in powder form and, due to the high internal friction, develops air pores that penetrate the cement paste. In order to achieve this internal friction, a mixing device is used which ensures that the material to be mixed is thoroughly stirred. In practice, counter-current mixers or large free-fall mixers have proven their worth. The result of this mixing process is a foamed cement matrix which essentially completely fills the voids between the expanded clay particles 31. In this way, a lightweight concrete with a low bulk density is produced, but which has sufficient strength to produce the desired static properties. The dry bulk density and associated technological properties such as compressive strength, bending tensile strength, thermal conductivity can be precisely controlled with the amount of cement added.

The material parameters for two variants are given below:

The bulk density class 0.6 can primarily be used for single-family and multi-family houses with conventional constructions, since the strength class LB 2 is sufficient for these constructions.

The insulation layer 4 is applied wet-on-wet to the base layer 3 made of light-weight aggregate concrete. The insulation layer 4 also has a pore structure, with expanded glass granules of the fraction 2-4 mm being used as an additive. To a small extent, expanded polystyrene 42 of 1 mm grain with a rough surface is also added to the insulation layer material. The amount of the polystyrene particles 42 is such that only a part of the free spaces between the expanded glass particles is taken up by it. In experiments, a proportion of 15-20% of the volume of the material space has proven to be advantageous. These components are bound with foamed cement paste, whereby foam pore formers are used as additives, which are essentially based on the basic materials hemoglobin and cellulose.

When mixed, this results in a heap-porous, largely mineral grain mixture, the remaining cavities of which are foamed Cement matrix are filled. These light aggregates are dosed according to their volume during the mixing process, while cement and the other additives are added by weight. In turn, mixers are used as the mixing device for producing the insulating layer material, which develop high internal shear forces in order to react the added air-entraining agent. Good mixing results were achieved with double-shaft trough mixers, in which the counter-rotating mixing shafts produce the necessary shear forces. It is also possible to completely empty the mixer.

The insulating layer material produced in this way is applied to the base layer 3 and then removed using a mechanically guided steel slat in order to produce a flat surface. This smooth removal of the outer surface of the insulation layer 4 is facilitated by the added polystyrene particles 42, which reduce the high internal friction between the individual expanded glass particles 41. The polystyrene particles 42 fill the cavities between the coarser expanded glass particles 41, as a result of which the cold bridges which may be present here are closed even better. Furthermore, the polystyrene particles 42 serving as “lubricants” enable better mixing of the insulation layer material, as a result of which more binder can be added and the insulation layer 4 thus has a higher strength.

The insulation layer 4 can have the following material characteristics: dry bulk density 280 kg / m ³ thermal conductivity 0.08 W / (mK)

The thermal insulation layer 4 produced in this way can be applied to the base layer 3 with a thickness of up to 16 cm.

In the present embodiment, the outer plaster layer 5 is applied on site at the construction site.

2 shows a vertical section through an outer wall of a building with three outer wall elements 1 arranged one above the other. An outer wall element 1 here has a recess for a window 6 and a roller shutter box 7. Furthermore, the insulation layer 4 is designed to protrude beyond the base layer 3, to avoid cold bridges in the area of false ceilings 8. In the base layer 3, empty tubes or sockets 9 for electrical installations can also be integrated.

In addition to the exemplary embodiments shown here, the invention permits further design approaches.

Zinc sterates can also be added to the insulation layer 4 in order to make the thermal insulation plaster water-repellent. Short-fiber mineral or plastic fibers can also be added to ensure the greatest possible freedom from cracks.

The base layer can also be produced using expanded clay of the fraction 4/8 mm and expanded glass of the fraction 2/4 mm. By partially replacing the expanded clay aggregate of the 4/8 mm fraction with expanded glass 2/4 mm, it is possible to reduce the dry bulk density of the base course without major loss of strength. With this mixed formulation, the base layer in strength class LB 2 can be produced with a dry bulk density of approx. 450 kg / m ³ . The thermal conductivity of the base layer thus produced is further reduced compared to the use of pure expanded clay (λ ~ 0.13 W / mk). In conjunction with the wet-on-wet insulation layer, it is possible to create a particularly highly heat-insulating wall element.

Furthermore, it is also possible to arrange plastic nails as anchoring between the light concrete layer and the insulation layer. For this purpose, the plastic nails are inserted into the wet lightweight concrete layer, for example in a grid of 75 cm from one another, during manufacture in such a way that they protrude by half their length and are covered by the insulating layer material subsequently applied. Depending on requirements, an increased number of plastic nails can be arranged in corner areas or on edges. For example, the plastic nails can have a length of 15 cm in the case of an insulation layer with a thickness of 16 cm. They can be designed with a barb section which is introduced into the lightweight concrete layer, while a spherical head or the like is embedded in the insulating layer material at the other end of the nail. The outer plaster layer 5 can also be applied to the insulation layer 4 in the formwork at the factory.

A further improvement in the surface quality is possible by applying a base coat. This can be applied wet on wet to the insulation layer material in a thickness of 5-10 mm. It is e.g. around a light foundation plaster, the bulk density of which is set so that neither expanded glass nor expanded clay floats when the wall elements are compacted. The strength development of this basic plaster is preferably set so that the solidification begins after approx. 1 hour and after the residence time of approx. 12 hours in the hardening chamber at 50 ° C has progressed to such an extent that the wall element can be easily removed from the mold, at the same time but is not yet too high, so that grinding is possible. The formation of sintered layers due to the high air humidity in the hardening chamber can be avoided. The strength and the modulus of elasticity are also adapted to the expanded glass thermal insulation plaster. The low vapor diffusion resistance value and the associated high vapor permeability support the formation of a favorable living climate. After grinding, the hardened base plaster is suitable for holding a silicate plaster primer and the subsequent silicate plaster or silicon silicate plaster.

Instead of the polystyrene particles 42, other lubricants can also be used. Unfoamed plastic particles or other fine-grained particles such as e.g. foamed perlite or expanded glass of the fraction 1-2 mm can be used, which can reduce the high internal friction between the individual expanded glass particles. However, these additives have a larger bulk density

Polystyrene particles, which results in less good thermal insulation properties.

The outer wall element 1 can also be manufactured and supplied without an interior plaster or exterior plaster layer in the formwork.

The multi-layer wall structure according to the invention is not only suitable for exterior walls of buildings, but can also be used as an exterior wall element for specially air-conditioned rooms inside buildings. In addition, that can External wall element can also be used as a partition between heated and unheated rooms within a building.

Furthermore, the multilayer outer wall element according to the invention also has improved sound insulation properties compared to conventional wall systems due to its construction.

The invention thus provides a method for producing a multilayer outer wall element 1, by means of which this can also be mass-produced with high quality of the outer surfaces. By admixing fine-grained particles as "lubricants", the high internal friction between the expanded glass particles 41 can be significantly reduced, as a result of which the outer surface of the pourable insulating layer material can be better leveled and better pouring is also possible. In addition, the added particles enable a better distribution of the Binder, which means that more binder can be added if necessary and thus also a better static strength or mechanical resistance of the insulation layer 4. If the fine-grained aggregate particles themselves are heat-insulating, such as foamed polystyrene, the thermal insulation properties of the insulation layer can also be improved 4 improve.

Claims

Expectations

1. A method for producing an at least two-layer outer wall element (1) for a building, comprising the steps:

a) Introducing pourable lightweight concrete into a formwork to form a base layer (3) of the outer wall element (1), b) applying pourable insulating layer material to the uncured base layer (3) to form an insulating layer (4) integrally connected to the base layer (3) ), c) smoothing the top of the insulating layer material, and d) curing the outer wall element (1),

wherein the insulation layer material by mixing expanded glass granules

(41) is produced with a cement matrix,

characterized in that

when mixing the insulation layer material, fine-grained particles (42) are also added.

2. The method according to claim 1, characterized in that particles (42) of expanded polystyrene is added.

3. The method according to claim 1 or 2, characterized in that the added particles (42) have a grain size of approximately 1 mm.

4. The method according to any one of claims 1 to 3, characterized in that the particles (42) are added in a small amount, in particular 15-20% of the volume of the material space.

5. The method according to any one of claims 1 to 4, characterized in that the added particles (42) have a rough surface.

6. The method according to any one of claims 1 to 5, characterized in that the lightweight concrete for forming the base layer (3) preferably has a pore structure and is produced by mixing expanded clay particles (31) with a cement matrix.

7. The method according to any one of claims 1 to 6, characterized in that the cement matrix is foamed and a foaming agent for foaming the cement matrix for the base layer (3) and / or for the insulation layer (4) based on the basic materials hemoglobin and / or cellulose .

8. The method according to any one of claims 1 to 7, characterized in that the insulating layer material zinc sterates are added.

9. The method according to any one of claims 1 to 8, characterized in that glass or plastic fibers are added to the insulating material.

10. The method according to any one of claims 1 to 9, characterized in that the mixing of the insulating layer material is carried out by a mixing device which produces high internal shear forces, and in particular by a double-shaft trough mixer.

11. outer wall element (1) for a building with a base layer (3) made of lightweight concrete and an insulation layer (4) integrally connected to the base layer (3), which has a mixture of a cement matrix and expanded glass granulate (41),

characterized in that

the insulation layer (4) also has fine-grained particles (42).

12. Outer wall element according to Anspmch 11, characterized in that the particles (42) are made of expanded polystyrene.

13. Outer wall element according to claim 11 or 12, characterized in that the added particles (42) have a grain size of approximately 1 mm.

14. External wall element according to one of claims 11 to 13, characterized in that the particles (42) are present in the insulating layer (4) in small amounts, in particular 15-20% of the volume of the material.

15. Outer wall element according to one of claims 11 to 14, characterized in that the added particles (42) have a rough surface.

16. Outer wall element according to one of claims 11 to 15, characterized in that the lightweight concrete of the base layer (3) preferably has a heap-porous structure and has a mixture of expanded clay particles (31) and a cement matrix.

17. Outer wall element according to one of claims 11 to 16, characterized in that a foaming agent for foaming the cement matrix for the base layer (3) and / or for the insulation layer (4) on the base materials

Hemoglobin and / or cellulose based.

18. Outer wall element according to one of claims 11 to 17, characterized in that the insulating layer (4) has zinc sterate.

19. External wall element according to one of claims 11 to 18, characterized in that the insulating layer (4) has glass or plastic fibers.