Method for manufacturing reusable concrete formwork panels and concrete formwork panels

Abstract

The invention relates to a method for manufacturing reusable concrete formwork panels and to a reusable concrete formwork panel in concrete casting. In order to provide a method for manufacturing concrete formwork panels which can be used multiple times and which is inexpensive to manufacture, and a concrete formwork panel, wherein the concrete formwork panel is also suitable for fair-faced concrete casting, a particle board or oriented strand board having two cover sides and side faces is first provided, a water-based two-component coating composition is then applied to at least one cover side in liquid form, wherein one component of the coating composition has a thermosetting carrier resin and the second component comprises at least one release agent component. Finally, the coated coating composition is cured in a hot press, thereby forming a closed coating on the particle board or oriented strand board.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing reusable concrete formwork slabs, particularly for fair-faced concrete, and a reusable concrete formwork slab for concrete pouring, particularly for fair-faced concrete. Background Technology

[0002] On construction sites, formwork is an essential auxiliary tool for various concrete operations. Existing technology includes not only high-quality, correspondingly high-priced formwork, but also lower-quality, correspondingly cheaper formwork.

[0003] High-quality formwork typically refers to system formwork used in conjunction with assembly / fastening systems, usually made of coated plywood or coated solid wood panels. This type of high-quality formwork is designed for long-term reuse. However, its reuse count is limited, typically ten to fifteen times. The disadvantages of these formwork panels are their high cost and lack of customization, as they cannot usually be cut to the required size.

[0004] Economical formwork panels typically refer to uncoated particleboard or oriented strand board (OSB). These panels are usually intended for single use only and are often left in place as so-called "residual formwork," such as in the soil of the foundation area. The disadvantages of these inexpensive but low-quality panels are that they cause demolding problems and damage when attempted to remove, making them unusable. Furthermore, the panels often swell upon initial use, which not only virtually eliminates the possibility of reuse but also creates an uneven, wavy texture on the concrete surface, making them unsuitable for fair-faced concrete. Additionally, these basic formwork panels often lack edge sealing, which also typically hinders reuse. In contrast, high-quality formwork panels, due to the significantly improved quality of the base material (plywood, wood), either require edge sealing or utilize a high-quality metal tongue and groove system, especially in so-called system formwork, which in turn increases manufacturing costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing a concrete formwork slab and a concrete formwork slab that can be used multiple times and has a particularly low manufacturing cost, wherein the concrete formwork slab is also suitable for pouring fair-faced concrete.

[0006] The object of the present invention is achieved by the method for manufacturing a reusable concrete formwork slab according to claim 1 and the reusable concrete formwork slab for concrete pouring according to claim 13. Advantageous embodiments are specifically described in the dependent claims, wherein features directly related to the method also apply to the concrete formwork slab, and features described for the concrete formwork slab are also features of the method.

[0007] In the method according to the invention for manufacturing reusable concrete formwork slabs, particularly for fair-faced concrete, firstly, a particleboard or oriented strand board having two cover surfaces and a side surface located therebetween is provided. Then, a water-based two-component coating composition is applied in a liquid manner to at least one cover surface, preferably to both cover surfaces, wherein one component of the coating composition has a thermosetting carrier resin and is particularly predominantly composed of it, and the second component includes at least one release agent component, preferably a release agent component. Finally, the applied coating composition is cured in a hot press under increased pressure and increased temperature, thereby forming a closed coating on the particleboard or oriented strand board.

[0008] The concrete formwork slab according to the invention for reuse in concrete pouring, particularly for fair-faced concrete, comprises a substrate made of particleboard or oriented strand board having two cover surfaces and sides, and a coating formed of a water-based two-component coating composition having at least one cover surface, preferably a coating with two cover surfaces, wherein one component of the coating composition has a thermosetting carrier resin and is formed primarily by it, the second component comprises at least one release agent component, and wherein the coating is formed by pressing the coating composition using a hot press to cure it under elevated pressure and temperature, and / or the coating is pressed into the surface of the substrate.

[0009] Surprisingly, coating particleboard and oriented strand board with a hot press and the coating composition according to the invention enables the low-cost manufacture of concrete formwork panels. This coating allows for good separation of the formwork panel from the concrete upon demolding after pouring, thus keeping the formwork panel essentially intact. Furthermore, the coating repeatedly ensures good surface quality of the poured concrete components; therefore, the concrete formwork panel of the invention can be reused for fair-faced concrete pouring even if the substrate is made of low-cost (oriented strand board). This is achieved particularly through the use of a water-based two-component coating composition containing a release agent component.

[0010] A concrete formwork slab is essentially understood as a single plate of formwork into which fresh concrete is poured and shaped until it sets and hardens fully, enabling it to bear its own and other loads and maintain the shape defined by the formwork. The concrete formwork slab not only determines the shape of the concrete but also forms the contact surface with the liquid concrete, thus significantly affecting its surface properties. Therefore, concrete formwork slabs are primarily used for forming formwork. Furthermore, concrete formwork slabs can be used with any setting and / or hardening building material, especially concrete, but also, for example, with any leveling material. Thus, although the primary design purpose of concrete formwork slabs is to form formwork for concrete elements, especially fair-faced concrete elements, their applications are not limited to concrete.

[0011] According to the present invention, the concrete formwork slab is reusable, meaning it can be used repeatedly for concrete pouring, and particularly preferably, it can be used immediately after demolding for the next concrete pour, especially without the need for recoating. Accordingly, the concrete formwork slab according to the present invention is reusable, preferably at least three times per concrete pour, more preferably at least five times, and most preferably at least ten times.

[0012] A concrete formwork slab can be simply a plate-shaped workpiece arbitrarily defined as part of a concrete formwork system, or it can be part of a formwork system with fixing elements fixedly disposed thereon. However, the concrete formwork slab according to the invention is preferably made only of a matrix or particleboard or oriented strand board (OSB), and / or without other components or fixing elements, so that it can be manufactured at particularly low cost, and, if necessary, can be made to customized sizes, for example, by cutting. Particularly advantageous is that the width of the (OSB) particleboard is typically up to 2800 mm. This allows all common concrete formwork specifications to be manufactured with minimal cutting waste.

[0013] According to the invention, the concrete formwork slab is based on particleboard or oriented strand board (OSB), which has two cover surfaces and a side surface located between the two cover surfaces, thus forming the matrix of the concrete formwork slab. Accordingly, the concrete formwork slab also preferably has a substantially constant thickness or material thickness over its entire surface. The two cover surfaces are preferably two opposing large-area surfaces of the particleboard or OSB. Accordingly, one cover surface preferably serves as the top surface of the particleboard or OSB, and the other cover surface preferably serves as the bottom surface of the particleboard or OSB. Preferably, the concrete formwork slab or the particleboard or OSB is rectangular and accordingly has four side surfaces.

[0014] In principle, particleboard or oriented strand board (OSB) can have either a surface that remains unchanged after board production or a processed surface. However, it is preferable to sand the surface of the particleboard, and especially the OSB, before applying the coating composition. In the method of the present invention, it is particularly preferable to provide sanded particleboard or OSB. However, alternatively, untreated and / or unsanded particleboard or OSB can also be used, thereby achieving particularly low-cost manufacturing of concrete formwork panels. Furthermore, it is preferable that the substrate or concrete formwork panel (except for the coating) is made solely of particleboard or OSB, and / or contains no other materials besides the materials of the particleboard or OSB and the coating composition.

[0015] Furthermore, it is preferable that each concrete formwork slab is made of a single type of particleboard or oriented strand board (OSB). The particleboard is preferably made only of wood shavings. Correspondingly, the OSB is preferably made only of coarse wood shavings. However, it is also conceivable in principle that the concrete formwork slab is not made of pure particleboard or pure OSB, but of multiple layers of composite board, wherein preferably at least one layer is a particleboard or OSB layer, more preferably the entire composite board is made only of particleboard and OSB layers. Most preferably, the composite board has an OSB layer as an intermediate layer and at least one particleboard layer as a capping layer, particularly having two capping layers made of wood shavings on both sides, so that the composite board has the appearance and surface of particleboard, and possesses the excellent strength and stiffness of OSB due to the coarse wood shavings in the intermediate layer.

[0016] To prevent particleboard or oriented strand board from expanding during contact with liquid concrete and to ensure reliable demolding for multiple uses, a coating is provided, which consists of a water-based coating composition. A water-based coating composition refers to a composition with water as the primary solvent and / or a hydrophilic and / or water-soluble composition.

[0017] According to the invention, the coating composition is applied in a liquid form to at least one cover surface. Accordingly, the coating composition is generally liquid or at least paste-like, preferably a coating composition with good flowability. The coating composition is preferably applied to the entire surface and / or covering the surface to be coated, especially the surfaces of both cover surfaces, so that a closed, complete and / or smooth coating is preferably obtained after curing.

[0018] The two-component coating composition can be applied in either a single layer or multiple layers. Typically, a single coat is sufficient. However, two or more coats may also be applied, preferably with intermediate drying between coats. In principle, intermediate drying can be achieved by any type of heating or radiation. Circulating air drying is preferred, especially circulating air drying using hot air, and / or infrared radiation. Furthermore, intermediate drying using heated rollers, heated surfaces, or heated tracks is also feasible.

[0019] In general, the coating composition can initially consist of any number of components. According to the invention, the coating composition is formed of at least two components, each of which can have any number of components. In principle, the two components of the coating composition are completely miscible and / or form a homogeneous, non-separating composition after mixing. Preferably, both components have permanent storage stability; more preferably, each component is a coating agent that can be used independently. However, alternatively, at least one component may be only an auxiliary substance or a mixture of several auxiliary substances. Furthermore, it is conceivable that one of the components is a solid, especially a powder. But generally, it is preferred that at least one of the two components is a liquid. It is also preferred that the coating composition and / or one of its components, more preferably, both components of the coating composition are primers.

[0020] According to the invention, the first component has a thermosetting carrier resin, and is therefore essentially thermosetting. The first component may consist solely or primarily of the carrier resin, or may contain any amount of other substances. Preferably, the first component consists of at least 60%, more preferably at least 80%, and most preferably at least 95% of the carrier resin or a carrier resin soluble in an aqueous solvent. Also preferably, the first component further comprises a film-forming powder, particularly a film-forming powder of at least one thermosetting synthetic resin, and more preferably, the first component is such a powder. The powder or the thermosetting carrier resin is preferably readily dispersible in water.

[0021] According to the invention, the second component has at least one release agent component or is a release agent component. This release agent component is designed to facilitate the separation of hardened concrete from the surface of the concrete formwork slab covered by the coating after the coating has cured. Accordingly, the release agent component helps to demold without damaging the concrete formwork slab. For this purpose, the release agent component is preferably permanently incorporated into the coating formed by the coating composition and / or uniformly distributed within the coating. Accordingly, the release agent component is not merely a temporary layer of material applied to the surface of the coating formed by the coating composition. Furthermore, preferably, the second component of the coating composition and / or the release agent component also fully cure within the coating. It is also preferably that the second component can be diluted with water.

[0022] Also preferably, the second component is a liquid; particularly preferably, the first component is readily and / or uniformly dispersed in the second component, or optionally dissolved in the second component. In principle, the two components of the coating composition can be mixed in any proportion, wherein the mass ratio of the first component to the second component is preferably between 1:3 and 1:1, more preferably between 2:5 and 2:3, most preferably between 4:7 and 4:10, and especially preferably about 1:2.

[0023] According to the invention, the coating composition is cured after application to form a closed coating on particleboard or oriented strand board. Curing is preferably at least partially thermally cured, more preferably substantially completely thermally cured, but any curing method, such as ultraviolet radiation curing, is also acceptable. In principle, thermal curing of the applied coating composition can be achieved by any heat input and / or by means of radiation, especially infrared radiation. This is preferably carried out in a hot press and / or by heated rollers and / or heated guides or surfaces. In principle, multiple curing steps, or even different methods, can be considered, but a single-step curing method is preferred.

[0024] According to the invention, the final thermosetting of the coating composition is carried out in a hot press, and thus at elevated temperatures and pressures. Upon curing, the coating is firmly bonded to the particleboard or oriented strand board, with the coating pressed at least onto the substrate surface, preferably into the substrate surface. Pressing into the surface primarily refers to the coating curing under pressure or during pressing, thereby pressing the coating composition onto the surface and into surface defects and unevenness, such as depressions, cracks, and / or irregularities, thus achieving particularly good adhesion and a smooth coating surface even in the presence of any surface defects and unevenness. Furthermore, it is conceivable to press a portion of the coating composition at least into the near-surface material layer of the particleboard or oriented strand board, thereby forming a particularly strong bond between the coating and the material surface.

[0025] In principle, concrete formwork slabs can be manufactured directly in a hot press without additional inserts such as pressure plates, partitions, and / or diaphragms. However, textures, such as wood grain or stone grain, can also be created in the concrete by using textured pressure plates. This can visually enhance the concrete surface. In principle, one side of the concrete formwork slab may be pressed without a pressure plate, or with a completely smooth pressure plate, and / or the other side may be pressed with a textured pressure plate, thus giving at least one side a texture transferable to the concrete member. Preferably, the two sides have different surface textures, allowing for the selective creation of smooth and textured concrete surfaces, or one of two possible textured concrete surfaces.

[0026] A preferred embodiment of the method for manufacturing reusable concrete formwork slabs according to the invention involves curing the coated composition in a short-cycle press, thereby achieving particularly rapid and high-quality manufacturing. Accordingly, the hot press is preferably a short-cycle press and / or not a veneer press. Furthermore, curing or pressing in a hot press, especially a short-cycle press, is preferably carried out without the need for interlayers or diaphragms, thereby simplifying the pressing process and making it more economical.

[0027] In principle, the curing of the applied coating composition can be carried out at any suitable duration, pressure, and temperature. In a preferred embodiment, the curing duration, especially the pressing time, of the applied coating composition is 10 to 120 seconds, preferably 15 to 60 seconds, more preferably 20 to 40 seconds, and most preferably about 30 seconds. Additionally or alternatively, the curing temperature, especially the pressing temperature, of the applied coating composition is 150°C to 250°C, preferably 175°C to 225°C, more preferably 190°C to 210°C, and most preferably about 200°C. Additionally or alternatively, the curing pressure, especially the pressing pressure, of the coated composition is between 25 kg / cm² (2.45 MPa) and 75 kg / cm² (7.35 MPa), preferably between 40 kg / cm² (3.9 MPa) and 60 kg / cm² (5.9 MPa), more preferably between 45 kg / cm² (4.4 MPa) and 55 kg / cm² (5.4 MPa), and most preferably about 50 kg / cm² (4.9 MPa).

[0028] In an advantageous improvement to the method of manufacturing reusable concrete formwork slabs according to the invention, the coating composition is applied by means of a roller coating system having a coating roller, thereby achieving a particularly simple, rapid, and uniform coating. Alternatively, it is also possible to use more than one roller for coating, for example, using two rollers arranged in a continuous row. However, it is generally preferred to use only one or more rollers for coating. In particular, coating is performed using one or more roller coating units. In principle, other coating methods, such as spraying, using one or more rollers alone or in combination, are also possible.

[0029] The coating amount can initially be chosen arbitrarily; however, too low a coating amount will result in insufficient reusability of the concrete formwork, while too high a coating amount will lead to reduced coating stability and an unnecessary increase in production costs. Accordingly, a preferred embodiment of the method of the present invention is that the coating composition is applied at a rate of 100 g / m² to 300 g / m², preferably 150 g / m² to 250 g / m², more preferably 200 g / m² to 240 g / m², and most preferably about 220 g / m².

[0030] A preferred embodiment of the method of the present invention is to apply the two-component coating composition directly to at least one cover surface and / or without a material layer disposed between the two-component coating composition and the cover surface and / or without a material layer impregnated with the coating composition. Direct application of the two-component coating composition refers to applying the two-component coating composition to the finished particleboard or oriented strand board (OSB), and / or directly to the surface of the particleboard or OSB. According to the present invention, this coating is performed using a liquid process, preferably only in a liquid manner, and / or without a solid carrier layer or material layer. Accordingly, it is preferred that the coating is performed using only liquids, and particularly preferably only with the two-component coating composition. Furthermore, when the two-component coating composition is directly applied, the particleboard or OSB has no other coating or is still in an uncoated state; therefore, the two-component coating composition preferably forms the first coating of the particleboard or OSB, and more preferably, forms the only coating. Coating without a material layer means that, preferably, no material layer is involved in the entire coating process of the two-component coating composition, regardless of whether the material layer has been impregnated. Examples of such unnecessary material layers are layers, especially rolls or layers made of paper, cardboard, nonwoven fabric, sulfurized fiber, woven and / or fibrous materials, wood, wood chips or wood fibers or any other material.

[0031] In an advantageous embodiment of the method of the invention, the coating composition is applied to at least two cover surfaces of the particleboard or oriented strand board, preferably also to the sides, and especially all sides of the particleboard or oriented strand board. While the coating of the front cover surface, which is in direct contact with the concrete, is particularly important, a corresponding coating of the back cover surface is also preferred. This is beneficial for increasing the possible number of reuses or extending service life, as damage from the back direction, especially expansion, is effectively prevented. A full and / or complete coating of the concrete formwork surface is particularly preferred, thereby reliably preventing expansion or the formation of bonds that can only separate from the concrete in the event of damage to the concrete formwork. Generally, it is preferred that all concrete formwork surfaces in contact with liquid and hardened concrete are coated.

[0032] Although concrete formwork slabs made of particleboard or oriented strand board according to the described method are capable of preventing water and / or concrete components from penetrating the surface, especially in areas covered by one or two layers, penetration can still occur in edge or side areas, particularly where the two-component coating composition is not applied or where the coating has been removed by cutting or milling the sides. This can lead to swelling or material damage in the edge or side areas of the concrete formwork slab. To prevent this, a preferred design of the method of the present invention is to perform a subsequent sealing treatment on the sides in addition to applying the coating composition, especially on one or two sides.

[0033] For this sealing process, a waterproof coating and / or a hot melt adhesive-based coating are preferred. Melt-bonded adhesives based on ethylene-vinyl acetate copolymer (EVA), polyamide (PA), and / or polyurethane (PU) can be used as hot melt adhesives, although other types of hot melt adhesives are also acceptable. To minimize the cost of side sealing, hot melt adhesives with high filler content and / or short open times are preferred. High filler content hot melt adhesives refer to melt-bonded adhesives with a filler content preferably at least 50%, more preferably at least 65%, and most preferably at least 75% (based on total mass). Besides cost, the desired environmental conditions for use with the concrete formwork will also influence the selection, because, for example, the melting point of ethylene-vinyl acetate copolymer-based hot melt adhesives is generally much lower than that of polyurethane-based hot melt adhesives, which should be considered, for example, when used in high-temperature regions during summer.

[0034] Additionally or alternatively, a preferred embodiment of the method of the present invention is that the side sealing is achieved by applying a coating, preferably by pressing it into the side material using rollers. Furthermore, after applying the sealant to the sides, excess sealant in the side areas can be removed, particularly by cutting with a blade and / or from the cover surface, and / or by smoothing the sealant using a second roller. The first roller used for application and / or the second roller used for smoothing is preferably heated, particularly to a temperature above the melting point of the hot melt adhesive. Generally, due to the more open edge structure of oriented strand board (OSB), its hot melt adhesive consumption is significantly higher than that of particleboard. However, OSB of the same material thickness has higher flexural strength than particleboard. Accordingly, thinner OSB than particleboard can be used. This is particularly important for heavier concrete formwork slabs, where OSB is preferred. Conversely, in cases where the slab size is small and side sealing is required, particleboard can be preferred due to lower material consumption during sealing.

[0035] Overall, it is particularly commendable that concrete formwork panels can be recycled after use. However, the coating material is applied at a relatively low level relative to the quality of the board or particleboard or oriented strand board, especially after crushing, which results in only minor issues when the recycled material is reused in the manufacture of wood products.

[0036] An advantageous improvement to the method of manufacturing reusable concrete formwork slabs according to the invention is that the second component of the coating composition, particularly the release agent component, does not contain adhesives used in the manufacture of particleboard or oriented strand board, and / or is not a synthetic resin, especially not melamine resin. Instead, in this two-component coating composition, at least one release agent component is used selectively in the second component based on its properties as a release agent, and these properties preferably do not arise as a side effect of surface coating with a synthetic resin layer.

[0037] Finally, a preferred improvement to the method of the present invention is that both components of the coating composition are independent and usable separately, and are mixed in a fixed proportion, particularly by mass or by volume, before coating. Mixing is particularly preferably carried out immediately before applying the coating composition. An independent and usable separately means that neither component possesses an absolutely essential ingredient for forming a coating with the other. Accordingly, it is preferable to use each of the two components of the two-component coating composition to form individual coatings, although such coatings may not possess the properties described in the present invention or be suitable for repeated use as concrete formwork slabs as described in the present invention.

[0038] In a preferred design of a concrete formwork slab, the thermosetting carrier resin includes, and is preferably, melamine resin. However, in principle, the use of condensation resins, either alone or in combination, as carrier resins can also be considered, particularly amino plastics such as melamine-formaldehyde resin, benzoguanamine resin, or urea-formaldehyde resin, or phenolic plastics such as phenolic resin. Additionally or alternatively, thermoplastic synthetic resins, such as diphenylmethane diisocyanate (PMDI), methylene diphenyl diisocyanate (MDI, or emulsified eMDI), or polyurethane, can also be used, either alone or in combination, as carrier resins.

[0039] Furthermore, in preferred concrete formwork slabs, the release agent component includes a release agent, particularly a hydrophobic agent, and most preferably, the hydrophobic agent itself. Additionally, the release agent component can also be a complete coating agent, either as a release agent or as a release agent component. Alternatively or preferably, the release agent component is capable of hydrophobizing the coating formed from the coating composition, i.e., imparting hydrophobic properties to the coating, especially surface properties. Alternatively or preferably, the release agent component can increase the contact angle between the coating and liquid concrete and / or reduce wettability. Detailed Implementation

[0040] The manufacturing method according to the present invention, as well as embodiments of concrete formwork panels and their reuse, will be described in more detail below.

[0041] Example 1 – Coating of Sanded Oriented Strand Board

[0042] A sanded oriented strand board (OSB) measuring 2800×2060×28mm is coated on both sides and the top surface using a roller coating unit on the production line, with a coating weight of approximately 220 g / m². The coating composition consists of two water-based components that are mixed immediately before coating. Each component is an independent coating or primer composition, with one component acting as a release agent, thus forming a release agent component. The coating composition is a mixture of 12 kg of Trollon Activator 2204 Yellow and 6 kg of Trollon Carrier 1400.

[0043] After mixing the two components of the coating composition, the first batch of concrete formwork panels is coated once, and the second batch of concrete formwork panels is coated twice, with drying in between by circulating air.

[0044] The coated concrete formwork slab is then cured in a short-cycle press for 30 seconds at a temperature of 200°C and a pressure of 50 kg / cm². The concrete formwork slab is easily detached from the press and can be transported out of the short-cycle press via a feed / discharge rack. Furthermore, no interlayer, especially a diaphragm, is required.

[0045] Supplementary tests using particleboard showed that concrete formwork panels based on particleboard, rather than oriented strand board, can also be manufactured using the same parameters.

[0046] Example 2:

[0047] First, a sanded oriented strand board (OSB) with the coating described in Example 1 and dimensions of 2650×2070×28mm was cut into original fixed dimensions of 2502×627×28mm on a cutting saw. Then, the resulting cut piece for concrete formwork was milled longitudinally to a specification of 625 mm on a double-end milling machine running at a feed rate of 20 m / min, first in a continuous pass.

[0048] Then, during a continuous pass, the two longitudinal edges of the concrete formwork slab are coated with an adhesive using a roller, particularly a high-fill, short-open-time EVA hot melt adhesive. This adhesive was chosen because it was necessary to fill the open areas of the OSB edges at the lowest possible cost. The hot melt adhesive is first pressed into the edges with a roller, then smoothed with a flat roller. Finally, any remaining hot melt adhesive on the top and / or bottom surfaces is removed with a spring-loaded scraper.

[0049] Next, the concrete formwork slab with the longitudinal edges already coated is rotated so that the transverse edges can be treated in the same way. First, the concrete formwork slab is milled to a size of 2500 mm, and then, following the same treatment method as the longitudinal edges described above, a layer of high-fill-rate, short-open-time EVA hot melt adhesive is applied to its edges.

[0050] Example 3 – Coating of Unsanded Oriented Strand Board

[0051] An unsanded oriented strand board (OSB) measuring 2800×2060×28mm was subjected to double-sided and full-coverage coating on the production line using a roller coating unit, with a coating weight of approximately 220 g / m². The coating composition consisted of two water-based components, which were mixed immediately before coating. Each component was an independent coating or primer composition, with one component acting as a release agent, thus forming a release agent component. The coating composition was a mixture of 12 kg of Trollon Activator 2204 Yellow and 6 kg of Trollon Carrier 1400.

[0052] After mixing the two components of the coating composition, a single coating was applied to the first batch of concrete formwork panels, and two coatings were applied to the second batch of concrete formwork panels, with drying via circulating air in between. Although release agent residue remained on the surface, surprisingly good coating results were observed, similar to those in Example 1.

[0053] The coated concrete formwork slab was then cured in a short-cycle press for 30 seconds at a temperature of 200°C and a pressure of 50 kg / cm². The concrete formwork slab easily detached from the press and could be transported out of the short-cycle press via a feed / discharge rack. Furthermore, no interlayer, especially a diaphragm, was required. Similar results to those observed in Example 1 were also observed here.

[0054] Supplementary tests using particleboard showed that concrete formwork panels based on particleboard, rather than oriented strand board, can also be manufactured using the same parameters.

[0055] Example 4 – Minimum Coating for Oriented Strand Board

[0056] A sanded oriented strand board (OSB) measuring 2800×2060×28mm was coated on both sides and top in a roll coating unit on the production line, with a coating weight of approximately 150 g / m². The coating composition was consistent with the composition in Example 1. High-speed single-pass coating was used to allow for the formation of individual coating defects.

[0057] Afterwards, the coated concrete formwork is cured again in a short-cycle press for 30 seconds at a temperature of 220°C and a pressure of 50 kg / cm².

[0058] Example 5 – Concrete Formwork Test

[0059] Cuttings are made from the coated concrete formwork panels manufactured in Examples 1, 2 and 3, and concrete formwork is then made from these cuttings. Each formwork has a size of 300×200×200 mm (length×width×depth).

[0060] Each mold was filled with commercially available leveling concrete. After the leveling material hardened, the leveling components were removed. Simultaneously, the ease of demolding, the thickness of the surface concrete layer, and the ease of brushing off residue were tested. This process was repeated seven times for each mold.

[0061] Of all the concrete formwork slabs inspected, only a slight decrease in demolding and scrubbing effectiveness was observed. As with other areas, no significant swelling or coating peeling was observed at the defects in Example 3. No ripple defects or other surface quality degradation were found on the concrete components.

Claims

1. A method for manufacturing reusable concrete formwork slabs, particularly for fair-faced concrete, comprising the following steps: - Available in particleboard or oriented strand board with two top and side panels. - Apply a water-based two-component coating composition in a liquid state to at least one of the cover surfaces. - Wherein, one component of the coating composition has a thermosetting carrier resin, and the second component includes at least one release agent component. - The coated composition is cured in a hot press to form a closed coating on the particleboard or the oriented strand board.

2. The method for manufacturing reusable concrete formwork slabs according to claim 1, characterized in that, The applied coating composition is cured in a short-cycle press.

3. The method for manufacturing reusable concrete formwork slabs according to claim 1 or 2, characterized in that, The applied coating composition is cured over a period of time between 15 and 60 seconds, especially during the pressing time.

4. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The coating composition is cured at a temperature between 175°C and 225°C, especially at a pressing temperature.

5. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The applied coating composition is cured under pressure between 40 kg / cm² and 60 kg / cm², especially under compression pressure.

6. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The coating composition is applied using a roll coating system having at least one coating roller.

7. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The coating composition is applied at an amount between 150 g / m² and 250 g / m².

8. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The two-component coating composition is applied directly to at least one of the cover surfaces, and / or applied without a material layer disposed between the two-component coating composition and the cover surface, and / or without a material layer impregnated with the coating composition.

9. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The coating composition is applied to at least two cover surfaces and / or the sides of the particleboard or oriented strand board.

10. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, In addition to applying the coating composition to one or both sides, the sides are also sealed, preferably using a waterproof coating and / or a hot melt adhesive-based coating, and / or preferably using a roller-applied coating.

11. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The second component of the coating composition, particularly the release agent component, does not contain adhesives used in the manufacture of the particleboard or oriented strand board and / or is not melamine resin.

12. A method for manufacturing reusable concrete formwork slabs according to at least one of the preceding claims, characterized in that, The two components of the coating composition are independent and can be used separately, and are mixed together in a fixed proportion before coating.

13. A reusable concrete formwork slab for concrete pouring, particularly for fair-faced concrete, comprising: -A substrate made of particleboard or oriented strand board with two top and sides. - At least one coating formed of a water-based two-component coating composition on the cover surface - wherein, one component of the coating composition has a thermosetting carrier resin, the second component includes at least one release agent component, and wherein, - The coating is formed by pressing the coating composition with the aid of a hot press to cure it, and / or the coating is pressed into the surface of the substrate.

14. The concrete formwork slab according to claim 13, characterized in that, The thermosetting carrier resin is melamine resin.

15. The concrete formwork slab according to claim 13 or 14, characterized in that, The release agent component imparts hydrophobicity to the coating formed by the coating composition, and / or the second component contains a hydrophobic agent as a release agent component.