EP1685932A1 - Method and device for the production of a lightweight building board - Google Patents

Abstract

A fresh concrete core layer is generated by applying fresh concrete to a continually moving first sub-layer. Outer layers (3a,3b) are generated on a continually moving second sub-layer. The prefabricated outer layers are applied to the core layer. A skein of layers is cut into single boards, which can then be joined to timber-work. The boards are dried as required. An independent claim is also included for a device for producing a multilayer light building board on a cement base with a core layer and outer layers on the main surface of the core layer.

Description

The invention relates to a method and an apparatus for producing a cement-based multilayer lightweight board comprising a core layer and at least one cover layer.

A general problem with the use of cementitious lightweight panels under humid ambient conditions is the high capillary water absorption due to the capillary channels and capillary openings in the cementitious stone matrix formed during the hydraulic setting process. This water absorption leads to swelling of the plates and expansion cracks of the cementitious material and concomitantly to loss of strength and chipping to the destruction of the attached to the lightweight board, such. an applied tiled surface. In addition, the frost resistance of such cementitious lightweight panels is very low.

Another problem in the production of cementitious lightweight boards is the formation of shrinkage cracks in the cement-stone matrix. These result from the fact that part of the mixing water is absorbed into the matrix but not chemically bound. Evaporation of this unbound capillary water from the already hardened product and the resulting stresses can cause cracks (shrinkage cracks) if the shrinkage stresses are greater than the tensile strengths of the cement matrix. These shrinkage cracks can additionally increase the capillary water absorption of the cement-stone matrix.

In order to still be able to use a cementitious lightweight board in a humid environment, several solutions are known.

A known from DE 197 04 961 C2 lightweight panel consists of a core layer of lightweight concrete, which is on both sides with a cover layer, in which different lengths, alkali-resistant textile glass fibers are introduced, is occupied. Into the core layer blown clay beads of fired expanded clay granules and, as reinforcement, alkali-resistant fibers, for example glass and / or synthetic fibers, are introduced as lightweight aggregate, whereby the bond between cover layer and core layer is improved. The clay beads in the core layer reduce the water absorbency of the lightweight board due to their closed-pore structure.

From US Pat. No. 3,284,980, a multilayer lightweight board for use particularly in a moist environment and a method for its production are known which consist of a core layer of concrete, preferably lightweight concrete, consisting of hydrated cement and aggregates, and two on the two main surfaces of the core layer, in Compared to this much thinner, cover layers also based on cement with an integrated reinforcing fabric, for example with an alkali-resistant coated glass fiber fabric, which reduces the water absorption of the core layer. As additives for the relatively light and porous core layer, for example, perlite, vermiculite, bulking slag or expandable shale are used, preferably in a ratio of 2: 1 to the volume of the cement content. The topcoat may contain to a lesser extent fine additives such as sand or fine bulking slag. Due to its weather resistance, the lightweight board is used according to the US 3,284.98 in the construction of walls and swimming pools. However, the water absorption of such a lightweight board with about 10 wt .-% is still relatively high.

According to US Pat. No. 3,284,980, the lightweight board is produced by placing a fabric layer in a form that is suitably coated with polyethylene and applying a mixture of the cover layer material having a suitable consistency in order to penetrate the fabric. Then, a mixture of the core material is applied, the surface of which is smoothed and applied thereon another layer of fabric and on this another layer of cement slurry and additives. In order to retain the moisture during the subsequent hardening, a further polyethylene layer or the like is applied to the last layer or the plate is steam-hardened. Thereafter, the hardened plate is removed from the mold.

DE 198 04 325 C2 describes a cement-based multilayer lightweight board and a method for its production, which also consist of a core layer of hydrated cement and lightweight aggregates and two cover layers arranged on the two main surfaces of the core layer and substantially thinner compared to this core layer Cement base with integrated reinforcing fabric, wherein at least the cement portions of the core layer are hydrophobized by the addition of suitable hydrophobing agents, so that the capillary water absorption of the lightweight board is within 24 h below 1 kg / m ² . As water repellents, according to DE 198 04 325 C2, metal stearates, in particular zinc, calcium and / or aluminum stearates, and oleates, in particular sodium oleates, have proven to be particularly suitable since they interact chemically with the cement content and, for example, form metal soaps to lead. The proportion of hydrophobing agent based on the solid portion of the core layer to be hydrophobized is less than 1 wt .-%. A particularly effective distribution of the hydrophobizing agent in the cement matrix is also described in DE 198 04 325 C2 with a relatively low proportion of water in reached the core layer. As extras, lightweight aggregates such as perlite, vermiculite, in particular in expanded form such as expanded slate, foam glass or crushed expanded clay, which can also be rendered hydrophobic in order to further reduce the water absorption of the lightweight panel. In addition, the cement content of the two outer layers arranged on the main surfaces of the core layer of the lightweight building board can also be rendered hydrophobic. The reinforcing fabric of the cover layers is for example a glass fiber fabric, which is provided with an alkali-resistant coating, for example made of plastic.

In the manufacture of the lightweight board, according to DE 198 04 325 C2, a mixture of the core material is applied to a first cover layer of glass fiber fabric laid in a cement slurry and covered with a second cover layer of glass fiber fabric laid in cement slurry. Subsequently, the plates are cut to a desired size.

Furthermore, from a prospectus "AESTUVER The universal fire protection board" Aestuver of November 1994, a multi-layer fire protection slab made of lightweight concrete is known, which has blown glass in the form of micro-glass bubbles and glass fibers in the matrix structure as an aggregate. This plate should have a low water absorption capacity.

Another method for producing a multilayer lightweight board, in particular a lightweight board according to US 3,284,980 is described in DE 29 10 432 C2. According to this method, a first continuous tissue, for example a glass fiber fabric, is first of all passed through a cementitious mortar bath and a metered deposition of the mortar on the fabric is effected by means of a scraping blade or a measuring device. Thereafter, the fabric is applied to a plurality of abutting carrier sheets lying on a conveyor belt, wherein the mortar is pressed by means of a pull rod as far into the interstices of the tissue that a certain amount remains on top of the fabric. Subsequently, the core material consisting of a lightweight concrete made of cement and light aggregate is added to the impregnated fabric and optionally compacted by means of one or more successively arranged distributor and connected to the first fabric. Then a second layer of mortar soaked with mortar is applied to the core layer and pressed in analogous to the first layer of tissue. The strand thus formed is cut in a cutting device transversely to the conveying direction between the abutting support plates into individual plates, which are then stacked and cured for further densification and bonding of the layers.

Another method for producing multilayer lightweight concrete panels with integrated reinforcement mats is described in DE 38 40 377 A1. According to this method, a first covering layer of a pasty cement mixture containing, for example, a hardening-accelerating agent and / or fly ash and a reinforcing mat continuously removed from a roll is placed on a continuously moving base, the reinforcing mat being replaced by a suitable material Consistency of the cement mixture is integrated into this. The resulting first cover layer is smoothed and calibrated, for example by means of rollers. In the course of the further movement of the base, a middle layer of a pasty, earth-moist cement mixture containing at least one additive such as sand and / or fly ash and / or perlite and / or vermiculite and / or polystyrene or the like and optionally also a hardening accelerating Contains agent and a condenser, applied, this smoothed and calibrated and then another reinforcing mat analogous to the first reinforcing mat placed under pressure application and smoothed and calibrated again. Subsequently, the application, smoothing and calibration of a further pasty cement mixture to form the second cover layer with the second reinforcing mat. The plate strand produced passes through a hardening channel for precuring, is then divided into individual plates and stored in stack form in a maturing store.

In the multilayer lightweight panels described, although the water absorption is lower compared to conventional cement-based lightweight panels, but the capillary water absorption, especially in the top layer is still relatively high, so that the water can penetrate through the cover layer to the core layer.

Although the water absorption of the core layer can be significantly reduced by the hydrophobing of at least the cement-containing portion of the core layer proposed in DE 198 04 325 C2, this method is relatively expensive, since a relatively large amount of hydrophobing agent is required.

In addition, due to the high proportion of cementum in the covering layer, shrinkage cracks in the covering layer can occur, which on the one hand lead to an increase in water absorption and, on the other hand, can impair the connection of the cementstone to the reinforcing fabric, so that the composite of the reinforcing fabric is disturbed by the cement-stone matrix and Strength of the lightweight panel can sink. Also, the deposits applied to the top layer can flake off due to the shrinkage cracks.

In particular, however, the different matrix structure of the core layer and of the cover layer may lead, due to the different physical and chemical properties, in particular of the different moduli of elasticity and strength properties, to the fact that the composite of the two layers is undercut Stress can be impaired, in particular in the case of temperature fluctuations, and under the influence of moisture due to the stresses occurring between the layers.

The object of the invention is to provide a method and an apparatus with which a multi-layer lightweight board in particular a multi-layer lightweight board based on cement, in which the water absorption of the lightweight board is already significantly reduced even without hydrophobing of the cement stone content of the lightweight board, also at the same time the lowest possible weight Lightweight panel anchoring a reinforcing fabric in the top layer and the connection of the core layer is improved with the top layer and flaking are avoided.

The object of the invention is also to provide a method and a device with which a multilayer lightweight board can be produced with simple and inexpensive means.

This object is solved by the features of claim 1 and with respect to the device by the features of the claim. Advantageous developments of the invention are characterized in the respective subclaims.

A multilayer lightweight board which can be produced according to the invention has a core layer and at least one, preferably two cover layers, which are or are arranged on one or on the main surfaces of the core layer, and cover the core layer. In relation to the core layer, the cover layers are also significantly thinner.

Essentially, the core idea of the lightweight board is to modify the cover layer with mechanical / physical means so that it is physically more resistant than the core layer. This is achieved in that the cover layer consists essentially of a solid mortar matrix consists of cement stone and at least one in particular closed-cell and / or closed-pored lightweight aggregate, in which at least one reinforcing agent z. B. a reinforcing fabric of z. B water-impermeable fibers is embedded.

Closed-cell means expanded body with a closed outer surface. Closed pore is a body that has closed pores.

The closed-cell lightweight aggregate is, in particular, unbroken expanded glass granules in the form of micro-glass hollow spheres or expanded glass beads. Closed-cell lightweight aggregates are, for example, broken or unbroken expanded clay granules in the form of expanded clay beads or expanded clay granules of fired clay granules.

The lightweight aggregate used here preferably has a particle size of 0 to 5 mm, preferably from 0.5 to 2 mm.

The reinforcing agent or reinforcing agent integrated in the solid mortar matrix is preferably a glass fiber fabric, preferably of E glass or AR glass, which is expediently provided with an alkali-resistant coating, or a fabric of plastic with a mesh width of preferably 2 to 8 mm, preferably 4 to 6.5 mm, and multifilaments having a width of preferably 0.5 to 1.5 mm, preferably 0.6 to 0.7 mm and a thickness of preferably 0.1 to 0.5 mm, preferably 0.15 to 0.3 mm or monofilaments with a diameter of preferably 0.1 to 0.5 mm, preferably 0.15 to 0.3 mm. In this case, a reinforcing agent is generally a textile fabric with lattice-like and / or lattice-like openings, for example a nonwoven fabric, for example a spunbonded fabric and / or in general, for example, a net, braid, knitted or knitted fabric.

As a reinforcing agent but also z. As fibers, scrims, nonwovens, mats, paper, metal mesh, perforated films or the like can be used.

To improve in particular the processability, the fresh mortar of the top layer expediently contains further customary additives such as pozzolans, for example fly ash, in particular hard coal fly ash and / or granulated and / or microsilica, and / or conventional additives such as air entraining agents and / or flow agents, for example polycarboxylate ethers and / or stabilizers, such as Methylcellulose and / or dispersing agents, e.g. a terpolymer of ethylene, vinyl laurate and vinyl chloride. As a cement Portland cement is suitably used.

In the following, preferred compositions of fresh mortars are given for cover layers according to the invention: raw material [Wt .-%] especially Portland cement 20-35 25-32 pozzolan 0-35 25-32 water 20-35 25-32 expanded glass granulate 7-20 10-15 superplasticizer 0-1 0.2-0.5 stabilizer 0-0.5 0.1-0.3 dispersant 0-4 2-3.5 Air-entraining agents 0-0.5 0.2-0.4

Preferably, a water / solids value w / f of from 0.35 to 0.6, preferably from 0.4 to 0.5 is set, so that the fresh mortar for the application of the top layer easily flow and is sprayable and has a slump of preferably 21 to 24 cm, preferably 21.5 to 23 cm according to DIN.

Furthermore, preferred compositions of hardened outer layers are given below: raw material [Wt .-%] especially Portland cement stone 30-60 40-50 pozzolan 0-50 30-40 expanded glass granulate 5-30 10-20 tissue 0.5-3 0.5-1

The sum of the fraction of closed-cell and / or closed-cell lightweight aggregate, in particular of expanded glass granules and the tissue fraction in the hardened outer layers, is preferably 8 to 20% by weight, preferably 10 to 15% by weight.

The proportion of air pores in the hardened outer layers resulting from the expedient use of the air entraining agent is preferably 5 to 30% by volume, preferably 8 to 15% by volume.

The core layer of the lightweight board according to the invention can be made essentially of cement, preferably Portland cement stone and at least one, especially a closed-cell and / or closed-porous lightweight aggregate, wherein for the core layer in particular unbroken expanded clay beads and / or expanded clay grains having a grain size of preferably 0 to 5 mm, preferably from 0 to 2 mm and the following particle size distribution. Grain size [mm] grain distribution especially [Wt .-%] 0.000 to 0.125 0-0.5 0-0.4 0.125 to 0.250 0-0.5 0-0.4 0.250 to 0.500 0-2.5 0-2 From 0,500 to 1,000 5-17 7-15 1,000 to 2,000 50-70 55-66 2,000 to 2,500 10-35 15-30

As further raw materials for the fresh concrete of the core layer it is expedient to use customary additives such as pozzolans, for example fly ash, in particular hard coal fly ash and / or blastfurnace slag and / or microsilica, and / or conventional additives such as air-entraining agents and / or dispersing agents, e.g. a terpolymer of ethylene, vinyl laurate and vinyl chloride and / or flow agents, for example polycarboxylate ethers.

In the following preferred compositions of fresh concrete for core layers of the invention produced lightweight board are given. raw material [Wt .-%] especially Portland cement 15-25 18-22 pozzolan 0-25 18-22 water 10-20 12-18 expanded clay granules 30-50 35-45 Air-entraining agents 0-0.5 0.1-0.3 superplasticizer 0-1 0.2-0.5 dispersant 0-4 1-2

Preferably, a water / solids value w / f of 0.15 to 0.3, preferably 0.2 to 0.25 is set, so that the fresh concrete for the core layer expediently has a soil-moist consistency and a low slump, for example, 16 to 18 cm according to DIN.

Furthermore, preferred compositions of hardened core layers of the lightweight panel obtainable according to the invention are specified below. raw material [Wt .-%] especially Portland cement stone 20-40 25-35 pozzolan 0-40 20-30 expanded clay granules 30-60 40-50

The proportion of closed-cell and / or closed-cell lightweight aggregate, in particular to expanded granules in the hardened core layer, is preferably 40 to 60% by weight, preferably 45 to 55% by weight.

The proportion of air pores in the hardened core layer resulting from the proper use of the air entraining agent is 10 to 50% by volume, preferably 15 to 25% by volume.

In addition, both the core layer and the cover layer may additionally be hydrophobed, preferably with silicone oil or silane / siloxane-based water repellents, in particular, in each case, the adjuvants, especially the closed-cell and / or closed-cell aggregates, such as the expanded glass granules and / or the expanded clay granules be rendered hydrophobic mixing with the cement content and optionally the additives and additives. Conveniently, the proportion of hydrophobing agent in the topcoat fresh mortar is from 0.1 to 0.5 wt%, preferably from 0.2 to 0.3 wt%, and in the fresh concrete for the core layer from 0.1 to 0.5 Wt .-%, preferably 0.2 to 0.3 wt .-%.

In the hardened layers, the proportion of hydrophobizing agent is suitably 0.1 to 0.7 wt .-%, preferably 0.3 to 0.5 wt .-% in the top layer and 0.1 to 0.6 wt .-%, preferably 0.3 to 0.4 wt .-% in the core layer.

In the following the invention will be explained in more detail by way of example with reference to the drawing.

• Fig.1: Schematisch einen Querschnitt durch einen Teil einer erfindungsgemäß herstellbaren Leichtbauplatte
• Fig.2: Schematisch einen Längsschnitt durch einen Teil einer erfindungsgemäßen Vorrichtung zur Herstellung einer Deckschicht und der Kernschicht einer mehrschichtigen Leichtbauplatte
• Fig.3: Schematisch einen Längsschnitt durch die erfindungsgemäße Vorrichtung im Bereich der Herstellung der zweiten Deckschicht

Show it:

• 1 shows schematically a cross section through a part of a lightweight panel which can be produced according to the invention
• 2 shows schematically a longitudinal section through part of a device according to the invention for producing a covering layer and the core layer of a multilayer lightweight building board
• 3 shows schematically a longitudinal section through the device according to the invention in the area of the production of the second cover layer

An inventive lightweight panel 1 according to Figure 1 consists essentially of a core layer 2, which is preferably covered on both sides with a cover layer 3a, 3b. The cover layers 3a, 3b each have a matrix of cement stone 5 and unbroken expanded glass granulate 6 and a reinforcing fabric 7 integrated with the matrix with warp threads 4 and weft threads (not shown). The core layer 2 essentially consists of a matrix of cement stone 8 and unbroken expanded clay granules 9 embedded in the cement paste 8. Furthermore, both the covering layers 3a, 3b and the core layer 2 have air pores 10, 11.

Expediently, the cover layers 3a, 3b have a thickness of 1 to 3 mm, preferably of 1.3 to 2 mm, and the core layer has a thickness of 5 to 100 mm, preferably of 8 to 60 mm.

The bulk density of the lightweight building board according to the invention is preferably between 500 and 1200 kg / m ³ , preferably between 600 and 1050 kg / m ³ .

The inventive device 100 shown in Figures 2 and 3 for the inventive production of a multilayer lightweight board substantially comprises a main supporting conveyor track z. B. a main belt line 101 with a moving in a main feed direction A with a main feed speed V _A main conveyor belt 114 and lying on the conveyor belt 114, in cross-section U-shaped forms 115 and above the main belt line 101 and preferably parallel to this arranged Nebenbandstraße 102 with a to the main conveyor belt 114 guided parallel supporting secondary conveyor z. B. a secondary conveyor belt, in particular a plastic film web 127, which is transported with one of the main feed direction A opposite sub-feed direction B and a magnitude of the main feed speed V _A corresponding sub-feed speed V _B stretched with suitable drive means. Conveniently, the film web 127 supported and / or driven on its underside by suitable means, such as rollers and / or another conveyor belt and / or sheets. The thickness of the plastic film web 127 is preferably 0.1 to 0.3 mm and its width preferably corresponds to the width of the molds 115.

The lying on the conveyor belt 114 and transported by this forms 115 expediently have two side walls 116a, a bottom wall 116b, and two end edges 117 and are open to the front and rear, where they are arranged one behind the other on the conveyor belt 114 of the belt line 101 that they bump with their front edges 117 together. The side walls 116a are expediently exchangeable, for example, by being attached to the bottom wall 116b by means of rails. As a result, the molds 115 can be adapted to the corresponding thickness of the lightweight building board to be produced. The molds 115 are preferably made of metal, preferably of steel and in particular of stainless steel, and have a preferred wall thickness of 3 to 5 mm. Furthermore, the molds 115 preferably have a length of 2000 to 3000 mm, preferably 2500 to 2700 mm and z. Example, a width of 1000 to 1500 mm, preferably 1200 to 1300 mm.

Above the conveyor belt 114, a first cover layer generating device 103 for generating and applying a first cover layer 3a of the lightweight board is arranged on the mold bottom 116b. Also arranged above the main conveyor belt 114 and arranged downstream of the first cover layer generating device 103 in the main feed direction A is a core layer generating device 104 for producing and applying the core layer 2 to the first cover layer 3a.

Subordinate to the core layer generation device 104 in the main feed direction A is the auxiliary belt line 102 arranged above the main belt line 101. This points in the secondary feed direction B successively arranged first above the film web 127, a second cover-layer forming device 105 for generating and applying the second cover layer 3b on the prestressed Kunststofstofffolienbahn 127 and a deflection and -auflegeeinrichtung 106 for applying the second cover layer 3b on the core layer 2, wherein the cover layer deflecting and laying device 106 is arranged downstream of the core layer generation device 104 in the feed direction A and is arranged above the main conveyor belt 114. The auxiliary belt line 102 is thus integrated into the main belt road 101.

The first cover layer generating device 103 essentially comprises a first injection device 103a with a storage container 111 in which the premixed fresh mortar 110 is kept ready for the cover layer 3a, and at the pumping lines 112, for example, above the bottom wall 116b and over the entire width of the molds 115 and transversely to the main feed direction A oscillating spray head 113 is connected.

Furthermore, the first cover layer generating device 103 in the main feed direction A downstream of the injection device 103a has a first reinforcement means feeder z. B. a first tissue applicator 103 b consisting essentially of a first fabric roll 118 a, on which a first reinforcement z. B. a first fabric tape 119 is wound, and a preferably obliquely below the fabric roll 118a and expediently according to the thickness of the first cover layer 3a spaced from the bottom wall 116b Auflegeolle 118b over which the first fabric tape 119 is guided under bias. Both the direction of rotation and the rotational speed of the two rollers 118a and 118b suitably correspond to the main feed direction A and the main feed speed V _A.

Downstream of the fabric application device 103b is a first indenting device 103c, which has a pressure rail 120 which can be moved up and down, the pressure rail 120 preferably being arranged so that it can be moved down to half the thickness of the first cover layer 3a away from the bottom wall 116b.

Downstream of the push-in device 103c in the main feed direction A, the core layer generating device 104 is provided, which has a rotary valve 122 for applying the freshly mixed fresh concrete 121 of the core layer 2 to the first cover layer 3a and one e.g. Transversely to the main feed direction A across the width of the molds 115 oscillating, the rotary valve 122 downstream doctor device 123 for uniform distribution of the fresh concrete 121 on the first cover layer 3a has. The doctor device 123 is preferably arranged above the first cover layer 3a at a distance from the desired thickness of the core layer 2.

The second covering layer generating device 105 arranged above the plastic film web 127, which is drawn off from a supply roll 128, essentially comprises a second spraying device 105a for spraying the fresh mortar 110 of the second covering layer 3b onto the plastic film web 127 by means of a second likewise transverse to the two advancing directions A and B and over the width of the plastic film web 127 oscillating spray head 125, which is supplied, for example, in turn via pumping lines of fresh mortar from a reservoir (not shown). In addition, the cover layer generating device 105 has a subordinate feed direction B of the second injection device 105a subordinate reinforcement medium provider z. B. a second fabric applicator 105b, which essentially has a second fabric roll 130a with wound fabric tape 131 and a suitably obliquely below the second fabric roll 130a and above the plastic film web 127 arranged Auflegerolle 130b, via which as a reinforcing means the second fabric tape 131 is also biased. Furthermore, the cover layer generating device 105 has a second push-in device 105c, in particular in the form of a second pressure rail 132 that can be moved up and down to integrate the fabric strip 131 into the cover layer 3b, which is preferably up to half the thickness of the first cover layer (3a) of the plastic film web (127 ) spaced is arranged lowered down.

Downstream of the push-in device 105c in the secondary feed direction B is the deflection and -auflegeeinrichtung 106, which consists essentially of a driven pulley 133 and a pressure roller 134 to the one under tension, preferably driven by the guide roller 133 Andrückband 135 with main feed speed V _A. circulates.

According to the invention, the deflection roller 133 is arranged above the conveyor belt 114 in such a way that its distance from the surface of the core layer 2 corresponds approximately to the thickness of the second cover layer 3b or is somewhat smaller. The pressure roller 134 adjoining the deflection roller 133 in the main feed direction A is expediently arranged at a slightly smaller distance than the deflection roller 133 from the core layer surface.

The continuous production of a lightweight board according to the invention with the device 100 according to the invention takes place as follows:

The pumpable, sprayable and free-flowing, premixed and expediently held ready in the reservoir 111 fresh mortar 110 for the production of the first cover layer 3a is fed via the pumping lines 112 to the transverse to the main direction A oscillating, stationary first spray head 113 and a compressed air jet in one thin layer injected in the main feed direction A moving forms 115, wherein the layer thickness over the Oszilliergeschwindigkeit, the feed rate of the belt and / or the flow rate of the mortar through the spray head 113 is adjustable.

Then, the endless fabric tape 119 for the first cover layer 3a is peeled off from the fabric roll 118 and deposited on the mold layer 115 in the mold 115 with slight prestressing. Expediently, the fabric band 119 is pressed into the fresh mortar 110 for embedding with the compressor rail 120 which can be moved up and down.

Next, the premixed, preferably earth-moist fresh concrete 121 for the core layer is applied via the rotary valve 122 to the first cover layer 3a located in the mold 115 and preferably distributed uniformly with the doctor rod 123 oscillating transversely to the main feed direction A.

For the production of the second cover layer 3b, the pumpable, sprayable and flowable fresh mortar 110 is also pre-mixed, for example, kept ready in a storage container and pumped via pumping lines into the second spray head 125 oscillating transversely to the secondary feed direction B and moved to the auxiliary feed direction B, with suitable means prestressed plastic film 127 sprayed. The plastic film web 127 is withdrawn from a supply roll 128.

In the mortar layer for the second cover layer 3b, the second fabric tape 131 is subtracted under pretension analogous to the method in the first cover layer 3a from the second fabric roll 130a, passed over the preferably driven Auflegerolle 130b, first deposited on the mortar layer and then expediently by means of the pressure rail 132 embedded and integrated into this.

Consequently, the second cover layer 3b is mirror-inverted or inversely and preferably parallel or simultaneously generated to the core layer 2 such that it is arranged with its lightweight panel surface to be formed at the bottom, in particular on the plastic film web 127.

Then, the plastic film web 127, together with the second cover layer 3b applied therefrom of fresh mortar 110 and fabric tape 131, is deflected downward by 180 °, for example, through the deflection roller 133 rotating at the main feed speed V _{A of} the belt line 101, so that the direction of movement and the speed of the plastic film web 127 with the cover layer 3b after the deflection roller 133 of the main feed direction A and the main feed rate V _A corresponds and the plastic film web 127 is above the second cover layer 3b and the second cover layer 3b is arranged with their Leichtbauplattenausßerifläche to uppermost.

Thus, the plastic film web 127 together with the cover layer 3b is placed on the core layer 2 located in the mold via the deflection roller 133 and expediently pressed against the core layer 2 by means of the pressure roller 134 and the pressure belt 135.

At a e.g. the guide roller 133 and / or the Nebenbandstraße 102 in the main feed direction A downstream cutting portal (not shown), the generated endless plate strand along the end edges 117 of the molds 115, for example, by means of a cutting wheel divided into individual plates.

Next, the individual shapes of the strip line are removed, stacked one above the other and fed to a setting channel in which they for example 5-15 hours at 40-50 ° C for setting dwell (not shown). Thereafter, the plastic film web is removed from the second cover layer and removed the lightweight board from the mold. The plastic film web is used, inter alia, by covering the surface of the second Cover layer during Abbindevorgang to keep the necessary water for hydration in the lightweight board or to protect the building board blank from drying out too fast.

Subsequently, the lightweight panels are stored in a dryer at e.g. Dried 50-60 ° C. The molds are cleaned and re-fed to the belt line.

By building a lightweight panel according to the invention with the high tissue content of z. As water-impermeable fibers, especially the high Glasfasergewebeanteil and the closed-cell expanded glass granules in the top layer to obtain a lightweight board whose water absorbency or - capacity is sufficiently low even without the addition of hydrophobing agent, especially because both the tissue and the closed-cell expanded glass granules absorb no water.

Thus, it is largely physically prevented that water penetrates through the cover layer to the core layer, so that swelling of the lightweight board and the associated expansion cracks and the spalling of the coating can be prevented.

In addition, the high proportion of glass fiber fabric and expanded glass granulate in the cover layer allows a low water / solid value w / f during production, with the result that shrinkage cracks, in particular in the cover layer, can be almost completely avoided.

The cement and the expanded glass granules in the top layer form a solid mortar matrix in which the reinforcing mesh is firmly embedded and anchored, so that a solid composite is formed, which also remains under load and moisture influence.

The lightweight panel produced according to the invention has a relatively homogeneous, almost monolithic matrix structure with correspondingly homogeneous low moduli of elasticity, whereby stresses occurring under load and moisture influence between the core layer and the cover layers can be dissipated in the structure without cracking.

In addition, the water absorption capacity of the lightweight board can be additionally reduced by the use of the closed-cell and / or closed-pore Blähtongranulats in the core layer, which absorbs little water in particular compared to conventional open-pored Leichtzuschlägen.

Furthermore, both surfaces of the cover layers on the one hand due to the closed cell lightweight aggregate and on the other hand by the production in the metal molds and on the plastic film web almost no visible pores and are relatively planar. This results from the fact that the cement paste can easily flow past due to the relatively smooth surface of the closed-cell lightweight aggregate and forms a thin layer of cement paste on the respective surface due to gravity.

The surfaces are characterized also relatively abrasion resistant. Even a thin plaster can be applied to these surfaces without any problems and without any problems.

Due to the shapes that can be adapted to the respective plate thickness, only as much space is required when stacking the plates still located in the molds, as dictated by the plate thickness.

The production of a lightweight board with the method according to the invention is thus very simple and inexpensive. In particular, the parallel or simultaneous generation of the second cover layer with opposite feed direction saves a great deal of time and strip length.

The inventive method has been described on the basis of a lightweight construction board with a special layer structure. However, this layer structure is not important. Rather, by the method according to the invention, multilayer lightweight panels, which have only one cover layer, can be made by first the core layer and then a cover layer is applied. Furthermore, it is also possible to dispense with the introduction of a reinforcing means or to introduce other than described reinforcing means into the covering layer. Accordingly, the structure of the device according to the invention can be adapted.

Claims (29)

Process for the continuous production of a cement-based multilayer lightweight board with a core layer (2) and with at least one cover layer (3a, 3b) arranged on a main surface of the core layer (2), comprising the following process steps: - Producing a fresh concrete core layer by applying fresh concrete on a first continuously moving pad. - Producing a cover layer (3b) on a second continuously moving pad and applying the prefabricated cover layer (3b) on the core layer (2). - Cutting the layer strand into individual plates. - allowing the plates to set. - If necessary, drying the plates. Method according to claim 1,
characterized in that
First, a first cover layer (3a) is produced by applying a fresh mortar to the first continuously moving base. Method according to claim 2,
characterized in that
on the fresh mortar of the cover layer (3a) a reinforcing agent, preferably a fabric tape is introduced. Method according to one or more of claims 1 to 3,
characterized in that
in the second cover layer (3b) a reinforcing agent, in particular a fabric tape is introduced. Method according to one or more of claims 1 to 4,
characterized in that
the second cover layer (3b) is mirror-inverted or inversely generated such that it is arranged with its lightweight panel surface to be formed at the bottom, and in particular on the continuously moving base, for which, for. B. the core layer (2) or the first cover layer (3a) and the core layer (2) is applied to the moving in a main feed direction A pad and the second cover layer (3b) on the in one of the main feed direction A opposite sub-feed direction B moving Produced pad and applied by deflecting the pad with cover layer by preferably 180 ° to the core layer (2). Method according to claims 1 to 5,
characterized in that
the reinforcement, z. B. the fabric tapes (119, 131), the first and second cover layers (3a, 3b) are pressed into the cover layers (3a, 3b). Method according to one or more of claims 1 to 6,
characterized in that
a fresh mortar is used for the outer layers (3a, 3b), the additives such as pozzolans, for example fly ash, in particular hard coal fly ash and / or granulated and / or microsilica, and preferably also conventional additives such as air entrainers and / or flow agents, for example polycarboxylate and / or stabilizers , such as methyl cellulose and / or dispersing agent, such as a terpolymer of ethylene, vinyl laurate and vinyl chloride. Method according to claim 7,
characterized in that
preferred compositions of fresh mortars for the cover layers (3a, 3b) are used as follows: raw material [Wt .-%] especially Portland cement 20-35 25-32 pozzolan 0-35 25-32 water 20-35 25-32 expanded glass granulate 7-20 10-15 superplasticizer 0-1 0.2-0.5 stabilizer 0-0.5 0.1-0.3 dispersant 0-4 2-3.5 Air-entraining agents 0-0.5 0.2-0.4 Method according to one or more of claims 1 to 8,
characterized in that
a water / solid value w / f in the fresh mortar for the cover layers (3a; 3b) is adjusted from 0.35 to 0.6, preferably from 0.4 to 0.5. Method according to one or more of claims 1 to 9,
characterized in that
for the fresh mortar for the outer layers (3a, 3b) a slump of 21 to 24 cm, preferably 21.5 to 23 cm according to DIN is set. Method according to one or more of claims 1 to 10,
characterized in that
a fresh concrete for the core layer (2) is used, the usual additives such as pozzolans, such as fly ash, in particular hard coal fly ash and / or granulated and / or microsilica, and preferably conventional additives such as air entrainers and / or dispersants, such as a terpolymer of ethylene, vinyl laurate and vinyl chloride and / or flow agents, for example polycarboxylate ether. Method according to claim 11,
characterized in that
preferred compositions of fresh concrete for the core layer (2) are used as follows: raw material [Wt .-%] especially Portland cement 15-25 18-22 pozzolan 0-25 18-22 water 10-20 12-18 expanded clay granules 30-50 35-45 Air-entraining agents 0-0.5 0.1-0.3 superplasticizer 0-1 0.2-0.5 dispersant 0-4 1-2 Method according to one or more of claims 1 to 12,
characterized in that
a water / solid value w / f in the fresh concrete for the core layer (2) is preferably adjusted from 0.15 to 0.3, preferably from 0.2 to 0.25. Method according to one or more of claims 1 to 13,
characterized in that
for the fresh concrete for the core layer (2) a slump of 16 to 18 cm according to DIN is set. Method according to one or more of claims 1 to 14,
characterized in that
the cover layers (3a, 3b) having a thickness of 1 to 3 mm, preferably 1.3 to 2 mm, and the core layer (2) having a thickness of 5 to 100 mm, preferably 8 to 60 mm, are produced. Method according to one or more of claims 1 to 15,
characterized in that
the second cover layer (3b) after deflection and laying on the core layer (2), in particular flat, for example, with a driven pressing belt (135) is pressed against the core layer (2). Method according to one or more of claims 1 to 16,
characterized in that
the fresh mortar for the cover layers (3a, 3b) onto the respective moving base, in particular by means of a spray head (113, 125) which oscillates transversely to the main feed direction A or sub-feed direction B and over the entire width of the molds (115) or the plastic film web (127). is sprayed on. Method according to one or more of claims 1 to 17,
characterized in that
the fresh concrete for the core layer (2) is uniformly distributed by means of a doctor device oscillating transversely to the main feed direction A. Device (100) for producing a cement-based multilayer lightweight board with a core layer (2) and a cover layer (3b) arranged on a main surface of the core layer (2), into which a reinforcing agent, for example, is preferably applied. B. a fabric tape (119, 131) is embedded, in particular for producing a lightweight board according to one or more of claims 1 to 18,
marked by a) a main conveyor z. B. a main belt line (101) having a main feed direction _A in a main feed speed v _A drivable main conveyor z. B. a conveyor belt (114) and preferably on the main conveyor (114) resting forms (115) b) an auxiliary conveyor belt (102) arranged above the main conveyor track (101) and preferably parallel thereto, to a secondary conveyor line (102) having a secondary conveying means guided parallel to the main conveyor means (114), in particular in the form of a tensioned plastic film web (127), which or into one of the Main feed direction A opposite sub-feed direction B can be driven with a magnitude of the main feed rate V _A corresponding sub-feed speed V _B , the main conveyor track (101) c) a first covering layer generating device (103), which is preferably arranged above the main conveying means (114), d) a core layer generating device (104), which is likewise preferably arranged above the conveyor belt (114) and optionally downstream of the cover layer generating device (103) in the main feed direction A. e) a cutting device for dividing a generated strand of sheet into individual sheets, f) a curing device or -strecke and g) preferably has a drying device, and wherein the secondary conveying path (102) in sub-scanning direction B is preferably arranged one after the other h) a second cover layer generating means (105) and i) a cover layer deflecting and laying device (106) , wherein preferably the cover layer deflecting and -auflegeeinrichtung (106) in the main feed direction A downstream of the core layer generating means (104) and the cutting device upstream of the Haüptförderbandes (114) is arranged so that the secondary conveyor track (102) with the main conveyor track (101) can cooperate , Device according to claim 19,
characterized in that
the first cover layer generating device (103) has a first injection device (103a), a first injection device (103b) and, preferably, a first push-in device (103c), arranged downstream of the main feed direction A. Device according to claim 20,
characterized in that
the first injection device (103a) has a storage container (111) and a pump line (112) arranged above a bottom wall (116b) of the molds (115) and oscillating over the entire width of the molds (115) and transverse to the main feed direction (A) ) with the reservoir (111) in conjunction spray head (113). Device according to claim 20 and / or 21,
characterized in that
the first laying means (103b) comprises a first reinforcing tape roll (118a) on which a first reinforcing tape z. B. a fabric tape (119) is wound, and a preferably obliquely below the roller (118a) and expediently according to the thickness of the first cover layer (3a) spaced from the bottom wall (116b) Auflegerolle (118b), via which the first reinforcing tape (119) is guided in particular under bias. Device according to one or more of claims 20 to 22,
characterized in that
the first push-in device (103c) has a pressure rail (120) that can be moved up and down, which is arranged so that it can be moved down to a distance of half the thickness of the first cover layer (3a) from the bottom wall (116b). Device according to one or more of claims 19 to 23,
characterized in that
the core layer generating device (104) has a rotary valve (122) and a squeegee device (123) which oscillates transversely to the main feed direction A over the width of the molds (115) and is arranged downstream of the rotary valve (122) in the main feed direction A, preferably above the first cover layer (3a). is arranged to the desired thickness of the core layer (2) spaced therefrom. Device according to one or more of claims 19 to 24,
characterized in that
the second cover layer generating device (105), in each case in the secondary feed direction B downstream of a second injection device (105a), a second fabric laying device (105b), and a second push-in device (105c). Device according to claim 25,
characterized in that
the second injection device (105a) has a second spray head (125) oscillating transversely to the secondary feed direction B and over the width of the plastic film web (127), and preferably a reservoir and pump lines. Device according to claim 25 and / or 26,
characterized in that
the second lay-up device (105b) a second tape roll (130a) with z. B. wound fabric tape (131) and a suitably obliquely below the second roller (130a) and above the plastic film web (127) arranged Auflegerolle (130b), via which the second fabric tape (131) is guided. Device according to one or more of claims 25 to 27,
characterized in that
the second push-in device (105c) has a second pressure rail (132) that can be moved up and down, which is arranged so that it can be moved down to a distance of half the thickness of the first cover layer (3a) from the plastic film web (127). Device according to one or more of claims 19 to 28,
characterized in that
the cover layer deflecting and laying device (106) has a deflection roller (133) and a pressure roller (134) around which a tensioning belt under tension (135), in particular with the main feed speed V _A , is circumferentially drivable.

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