PL240202B1 - Facing concrete panel and method for producing a facing concrete panel - Google Patents

Description

PL 240 202 B1

Description of the invention

The subject of the invention is a method of manufacturing an exposed concrete slab containing a concrete mass with a decorative face, intended in particular for facade, terrace or roofing applications.

Facing concrete slabs (Sichtbeton; architectural concrete) are known and used for cladding facades of buildings or interior walls, replacing plaster finish or ceramic cladding. In addition, such concrete slabs are used as roofing and as surfaces of terraces or passageways. They can also be used as floor coverings inside buildings. Such boards are most often glued or fixed with anchors or catches.

The main problem when using facing concrete slabs is the need to provide adequate insulation and protection against moisture. For this purpose, additional separate thermal insulation boards are used, for example, polystyrene or polyurethane. The insulation boards are glued or mechanically fixed. The insulation foam can also be sprayed onto the concrete surface, but without the possibility of precise control of the insulation thickness. The insulating layer can also be formed by injecting a liquid insulating material or its reactive components into a chamber formed by two concrete slabs. This is the so-called sandwich system. Protection against moisture is to be provided by insulating inserts in the gaps between the boards or by cement or plastic joints.

EP 0 379 980 discloses a sandwich-type façade panel with two load-bearing layers and at least one insulation layer arranged therebetween. The load-bearing layers are made of fiber-reinforced concrete. The plate layers, together with the insulating layer, are connected with each other by non-metallic fastening elements.

From FR 2 421 057 panels are known which consist of two outer concrete layers with an insulating layer between them. The concrete layers are connected at regular and constant intervals with lightweight concrete ribs. The outer layer of concrete contains a reinforcing mesh and the inner layer is unreinforced. The middle insulating layer of the slab is expanded polystyrene and is produced in situ between the outer concrete layers. The connecting ribs can be poured with the outer layers.

From DE 198 48 154 a cladding panel is known, consisting of a core made of homogeneous porous lightweight concrete with a density lower than 1.0 kg / dm ³ . The core is covered with reinforcing layers that stabilize it mechanically.

From FR 2 962 462 a monolithic construction plate is known which comprises two external concrete layers between which an internal heat or sound insulation layer is located. This layer is made of polyurethane or expanded polystyrene and plant fibers. The method of producing such a slab consists in pouring a first concrete slab, laying an insulating layer on it and pouring it with a second outer layer of concrete.

US 4,010,232 and GB 1,523,858 disclose a method of producing a construction board comprising interconnected layers of concrete and foamed polyurethane, comprising the following steps: spreading a wet cement mixture layer in a mold; sprinkling the wet mix layer with the dry cement mix until a dry cement mix layer is formed on said wet cement mix layer; pouring a foamable urethane reaction composition onto said dry layer; mold closure; allowing the urethane reaction mixture to expand to form a urethane foam. The dry layer of the cement mixture prevents the ingress of moisture from the wet cement mixture layer into the foaming urethane reaction mixture.

The aim of the invention is to introduce a composite slab with a concrete load-bearing layer and a polyurethane heat-insulating layer, with insulation properties selected in such a way that the concrete layer exhibits similar properties to polyurethane, i.e. diffusion, water absorption and vapor-permeability, which, thanks to the homogeneous properties of the joined materials, leads to a stable joint in a thin layer. plate.

The essence of the method according to the invention consists in the fact that in the first stage the facing layer of the concrete slab is prepared using a known airtight press and using a concrete mixture containing the following components in amounts from to: sand 0 0-2 mm, in the amount of 1500-1550 kg / m ³ , stone flour or dust 0 0-0.5 mm, in the amount of 350-400 kg / m ³ , cement RH 42.5, in the amount of 450-500 kg / m ³ ,

The amount of plasticizer is 0.5-0.8% by weight of the cement. The prepared starting material is pressed in a hermetic press at a pressure of 1400 t / m ² at a temperature of 30-40 ° C and for 15 sec to 18 sec.

In the second stage, an insulating layer of closed-cell polyurethane is directly applied to the concrete slab using a pressure press with the possibility of regulating pressure and temperature, at a pressure from 134 kG / m ² to 154 kG / m ² , at the dosing temperature of component A and B (resin and hardener) from 30 to 40 ° C, for 2½ to 3½ minutes, using the flood-pressure technology, while the concrete slab in the mold is kept at the temperature of the active concrete surface from 20 to 30 ° C, so as to keep it properly at in relation to the dosing temperature of polyurethane foam components without thermal shock.

In the terrace variant, in the facing layer under the insulation layer, an additional structural core is made, for which a concrete mixture is used containing the following components: aggregate by 0 6-8 mm, in the amount of 400 kg / m3, aggregate by 0 4-6 mm, in the amount of 850 kg / m ³ , sand 0 0.2 mm, in the amount of 800 kg / m ³ cement RH 42.5, in the amount of 350 kg / m ³ , plasticizer in the amount of 0.8-1% of the cement mass.

Optionally, before applying the insulating layer, the front surface of the panel is subjected to a mechanical finishing treatment by grinding, polishing, brushing, sandblasting or shot blasting. Before applying the insulating layer, it is also possible to apply a protective layer on the front surface of the board or to print a decorative layer.

The facing concrete slab, intended in particular for facade, terrace or roof applications, made according to the invention, has an insulating layer applied on the inner surface of the facing layer opposite to its outer face, which is integrated with the facing layer and constitutes an integral structure of the slab with only one concrete layer. carrying weight. The thermal insulation is made of a closed-cell polyurethane layer with a density of 35 to 160 kg / ^m3 . In a variant, the board in the facing layer has an additional structural core. The insulating layer of the board has a tongue-and-groove arrangement of the edges.

The advantage of the solution according to the invention is that a ready-to-use product can be obtained at the production plant - a composite insulated facing board - having thermal insulation parameters and stiffness appropriate to the requirements, while ensuring a stable connection of the composite layers.

The composite concrete-polyurethane slab according to the invention has very good insulating properties, resistance to acids, chemical and biological agents, with no water absorption of the insulating layer in combination with concrete as a functional layer protecting against mechanical loads, abrasion as well as UV radiation. In addition, the board is characterized by an increased diffusion resistance, which significantly reduces the condensation of water vapor, which is very important for the insulation of rooms where the diffusivity of the insulation is too high or where there is moisture and mold may form in the insulated room.

According to the invention, therefore, a new product of relatively low weight is obtained, which is both a facade and a terrace material, to be used wherever insulation, UV resistance, abrasion resistance and mechanical loads are required.

For façade use, a product is obtained that is very quick to install, with very good insulation parameters, and at the same time quite thin, which saves the reconstruction of windows which, due to thick insulation, have collapsed inside.

For surface use, thanks to the introduction of a tongue-and-groove connection system in the insulation layer, it is also possible to very quickly lay a terrace or roof surface, which is not permanently attached to the ground, water-tight, stable, easy to lay, with a low weight and well insulating. The use of a tongue-and-groove system also solves the problems with dilatation of the material while maintaining its tightness on the arranged surface, as part of the tensile and shrinkage stresses will be taken over by the panel joining system.

The solution according to the invention is explained with reference to the drawings, in which:

Fig. 1 shows a concrete slab in view showing individual layers, Fig. 2 shows a variant of the slab with an additional structural core, Fig. 3 shows a schematic diagram of the technological process of producing a concrete slab.

The examples are for a façade slab and a terrace slab. The concrete slab consists of a facing layer 1 which has a decorative outer surface 2. The inner surface of the facing layer 1 opposite to the decorative surface 2 is adhered to and integrally bonded to it

An insulating layer 3 made of closed cell polyurethane, foamed on this surface, with a density of 35 to 160 kg / ^m3 . The insulation layer 3 is integrated with the facing layer 1, constituting an integral structure of the slab with only one concrete bearing mass.

The insulating layer 3 has opposite edges provided with a tongue 4 and a corresponding groove 5. In the facade board, the insulation layer 3 is bonded directly to the facing layer 1. In the terrace variant, an additional structural core 6 is inserted into the facing layer 1.

The panel in question was produced by the method according to the invention according to the scheme of Fig. 3, in which the individual symbols represent:

PM - preparation of the concrete mixture of the facing layer

WL - creating the facing layer

WK - optional addition of a mixture for the construction core

OW - optional mechanical processing of the facing layer

OO - optional application of a protective layer on the facing layer

OD - optional application of a decorative layer on the facing layer

PU - application of a polyurethane insulation layer.

P r z k ł a d I - facade panel

A mixture was prepared for the production of a concrete facing layer with the following composition: - sand of 0 0-2 mm, in the amount of 1550 kg / m ³ - stone flour or dust 0 0-0.5 mm, in the amount of 400 kg / m ³ - RH cement 42.5, in the amount of 500 kg / m ³ - plasticizer in the amount of 0.5% of the cement mass

The prepared starting material was pressed in a hermetic press at a pressure of 1400 t / m ² at a temperature of 40 ° C and for 15 sec. A concrete slab with a thickness of 0.18 cm and a concrete density of 2400 kg / m ² was obtained.

The board prepared in this way was placed in a high-pressure press and components A and B were fed to the production of polyurethane foam. The pressure was 134 kG / m ² , the temperature of ingredients dosing 30 ° C, during 2½ min. The active surface of the concrete slab was kept at a temperature of 20 ° C.

A concrete slab was obtained with an integral polyurethane insulating layer 8.18 cm thick using a polymer with a density of 35 kg / ^m3 .

P r x l a d II - terrace or roof slab

A mixture was prepared for the production of a concrete facing layer with the following composition: - sand of 0 0-2 mm, in the amount of 1500 kg / ^m3 - stone flour or dust 0 0-0.5 mm, in the amount of 350 kg / ^m3 - RH cement 42.5, in the amount of 450 kg / m ³ - plasticizer in the amount of 0.8% of the cement mass

- as well as a mixture for making an additional structural core containing the following ingredients:

- aggregate by 0 6-8 mm, in the amount of 400 kg / m ³

- aggregate by 0 4-6 mm, in the amount of 850 kg / m ³

- sand 0 0.2 mm, in the amount of 800 kg / m ³

- cement RH 42.5, in the amount of 350 kg / m ³

- plasticizer in the amount of 1% by weight of cement

The prepared starting material was poured into the mold, successively - the mixture for the facing layer and then the mixture for the structural core, pressed in a hermetic press at a pressure of 1400 t / m ² at a temperature of 40 ° C and 18 sec. A concrete slab with a thickness of 4 cm and a concrete density of 2400 kg / m ² was obtained.

The board prepared in this way was placed in a high-pressure press and components A and B were fed to the production of polyurethane foam. The pressure was 154 kG / m ² , the temperature of ingredients dosing 40 ° C, during 3½ min. The active surface of the concrete slab was kept at a temperature of 30 ° C.

A concrete slab was obtained with an integral polyurethane insulation layer 6 cm thick and with a strength of 400 kPa, using polyurethane with a density of 160 kg / ^m3 .

It is advisable to prepare the concrete facing layer in such a way that its water absorption is not greater than 3% (the less the better), and for the visible plane, it is best to create a completely non-absorbent but diffusive surface.

PL 240 202 B1

On the visible surface, you can additionally apply an impregnation or a protective layer (coating), which will completely seal the concrete surface against water.

At the wet stage of the technological process, the surface of the board can be refined by a water scrubber in order to obtain a different texture.

The concrete element prepared in this way can be combined with closed cell polyurethane and has similar properties as polyurethane, i.e. diffusion, water absorption and vapor-permeability, which makes the two materials to be combined very homogeneous in this respect.

The concrete slab produced on a hermetic press, after passing the entire production line, is characterized by two important parameters that are practically impossible to achieve with other known technologies such as vibropress, Wet-Cast, extruder, because they do not allow for the minimum thickness of the manufactured elements (which strictly related to the weight of the elements) while maintaining the building standards required by law for bending strength. The slabs also have surfaces with high concrete density, because the visible layer of the terrace slab and the entire facade slab in the production process are wet concrete, so that the surface also has an appearance similar to that of a ceramic slab.

In the production of polyurethane elements, a high-pressure flooding system is used to connect the concrete surface with the polymer.

This system allows for better mixing of A and B factors as mixing takes place in a high pressure jet chamber. The production is carried out without waste and there is no need to clean the dosing head, which is the basic drawback of the low-pressure system, where poor mixing of ingredients takes place, relatively large waste and the need for periodic cleaning of the dosing nozzle. High mixing pressure results in a very homogeneous mixture which has a huge impact on the quality, speed and repeatability of the process.

The optimal temperature in the mold during dosing is 30 ° C-40 ° C and maintaining this parameter is the most important in the entire process, as it determines the quality of the foam, its homogeneity, and its mechanical and physical parameters. The process of forming foam in the mold is an exothermic process, reaching up to 80 ° C, so it must be possible to cool the mold.

Too high temperature in the mold leads to too quick gelation of the foam surface, which results in an uneven structure and flow in the mold, and in extreme cases the foaming component is torn and deep cavities are formed.

In turn, too low a temperature results in a longer gelation period and weaker cell formation, which affects the quality of the foam. Specially designed forms of aluminum, the technology of cooling the process and temperature control in the process allow to achieve the desired product parameters and its repeatability.

Another important factor determining the stability of the process is the surface temperature of the concrete element involved in the combination with polyurethane. Assuming that concrete with very low water absorption and diffusion is obtained, the active surface should be kept at a relatively constant temperature in the pressure injection process, between 20 ° C-30 ° C, which will not cause temperature shock when these two media come into contact. . Such adjusted temperatures and pressure allow the specific surface of the polyurethane foam in the concrete to reach the specific surface, which results in a very durable and stable joint. The lack of an intermediate layer results in a very stable connection system.

The polyurethane foams available on the market differ in basic parameters, such as density between 15 kg / m3 ^and 200 kg / ^m3 , which affects their thermal conductivity coefficient from 0.016-0.035 W / m2 / K, with shear strength up to 450 kPa.

Within the scope of a given agent to be applied, it is also possible to change the parameters of the foam by applying higher pressure or intensity parameters of the foaming agent. You should be careful, because too high pressure of the dispensed foam may cause its destruction by cracking from the inside.

As a standard, it should be assumed that polyurethane foams with a minimum density of up to 35 kg / m ³ and possibly large chambers are used for the facade panels. The thickness of the layer depends on the assumed heat transfer coefficient, and with facade panels it is assumed that there are no other loads on the foam itself.

In turn, the thickness of the layer for the terrace slab depends on such parameters as: heat transfer coefficient, compressive strength. Depending on the assumed design parameters

Claims (5)

The desired product can be obtained by adjusting the density of the foam and its thickness. Assuming that the concrete slab has adequate strength, it can, for example, be assumed that with a density of 60 kg / m ³ and a thickness of 5 cm, a surface with a compressive strength of 10 t / m ² is obtained. Patent claims 1. A method of producing an exposed concrete slab containing a concrete mass with a front facing surface and an insulating layer in the form of polyurethane foam, characterized in that - in the first stage (PM), the facing layer (1) of the concrete slab is prepared using a known airtight press and using a concrete mixture containing the following components in amounts from to: • sand 0 0-2 mm, in the amount of 1500-1550 kg / ^m3 • stone flour or dust 0 0-0.5 mm, in the amount of 350-400 kg / ^m3 • cement RH 42.5, in the amount of 450- 500 kg / m ³ • plasticizer in the amount of 0.5-0.8% of the cement mass. The prepared starting material is pressed (WL) in a hermetic press at a pressure of 1400 t / m ² at a temperature of 30-40 ° C and during 15 sec to 18 sec, - in the second stage (PU), an insulating layer (3) made of closed-cell polyurethane is applied directly to the concrete slab using a pressure press with adjustable pressure and temperature, • at a pressure from 134 kG / m ² to 154 kG / m ² • in dosing temperature of component A and B - resin and hardener - from 30 to 40 ° C • for 2½ to 3½ minutes using the flood-pressure technology, while the concrete slab in the mold is kept at the temperature of the active concrete surface from 20 to 30 ° C so as to maintain it appropriately in relation to the dosing temperature of the polyurethane foam components without thermal shock. 2. The method according to p. 1, characterized in that in the facing layer (1), under the insulation layer (3), an additional structural core (6) is produced, for which a concrete mixture containing the following components is used: • aggregate by 0 6-8 mm, in the amount of 400 kg / m ³ • aggregate by 0 4-6 mm, in the amount of 850 kg / m ³ • sand 0 0.2 mm, in the amount of 800 kg / m ³ • cement RH 42.5, in the amount of 350 kg / m ³ • plasticizer in the amount of 0.8-1% of the cement mass 3. The method according to p. The front surface (2) of the panel is subjected to a mechanical finish (OW) by grinding, polishing, brushing, sandblasting or shot blasting prior to the application of the insulating layer (3). 4. The method according to p. The method according to claim 1 or 2, characterized in that a protective layer (OO) is applied to the end face (2) of the board before the insulating layer (3) is applied. 5. The method according to p. A decorative layer according to claim 1 or 2, characterized in that prior to the application of the insulating layer (3), a decorative layer is printed (OD) on the front surface (2) of the panel.