Method of carrying out exposed aggregate textured concrete finishes

Abstract: A method of carrying out aggregate exposed finishing for concrete capable of very much reducing the amount of decorative aggregates used, and of facilitating the work without requiring long working times and high level techniques, comprises the steps of: loading aggregates (3) on an adhesive sheet (1,2); burying part of the aggregates (3) in an adhesive layer (1) of the adhesive sheet (1,2); applying mortar or concrete (4) onto an aggregate loading surface of the aggregate loading adhesive sheet (1,2); hardening the mortar or concrete (4); and removing the adhesive sheet (1,2).

Description: The present invention relates to a method of carrying out aggregate exposed finishing for architectural decorative concrete, and particularly to a method of carrying out aggregate exposed finishing for concrete which is capable of very much reducing the amount of expensive decorative aggregates used, and of facilitating the work without requiring long working times and high level techniques. For carrying out aggregate exposed finishing for decorative concrete, there has until now been mainly used a technique called a washing method. In this washing method, mortar mixed with aggregates is placed on the concrete substrate and the mortar on the surface is washed away while the mortar is still plastic to expose part of the aggregates. In recent years, there has been a tendency to use a technique in which mortar mixed with aggregates is placed on the concrete substrate and then a surface retarder is sprinkled on the surface of the mortar. Further, a special sheet called a retarder paper tends to be used. In these methods, the hardening of the mortar on the surface is retarded, and when only the interior of the mortar is hardened, the unhardened surface layer is washed away, to expose part of the aggregates. However, the prior art washing methods described above have the following disadvantages: namely, a large amount of inorganics containing heavy metals and the like must be treated because mortar is washed away with a large amount of water; expensive decorative aggregates in an amount more than is necessary must be used; and long working times and techniques requiring a high level of skill are required for carrying out decorative finishing with complicated patterns. Thus, there have been strong demands for solutions to the above disadvantages. EP-A-0422340 discloses a method of producing decorative concrete panels, which uses a water-absorptive resin to cover part of the aggregate stones before the cement is added, resulting in the stones remaining visible in the completed panels. FR-A-2192488 uses a flexible layer for a similar purpose. To solve the above problems of the prior art, the present invention has been made, and an object of the present invention is to provide a method of carrying out aggregate exposed finishing for concrete capable of very much reducing the amount of aggregates used, and of facilitating the work without requiring long working times and high level techniques. Therefore the present invention provides a method of making an aggregate exposed finish for concrete using an aggregate loaded flexible adhesive sheet and having adhesive properties such that the adhesive strength thereof is sufficient to retain the aggregate before the hardening of mortar or concrete, and comprising the steps of: (a) loading aggregates on an adhesive sheet; (b) applying mortar or concrete onto an aggregate loading surface of said aggregate loaded adhesive sheet; (c) hardening said mortar or concrete; and (d) removing said adhesive sheet to expose the aggregate exposed finish of the concrete; characterised in that: the flexible sheet is an adhesive sheet made of a heat-resisting substrate and hot-melt adhesive coated thereon, in that the adhesive strength decreases in contact with hardening mortar or concrete to the extent of facilitating removal of said adhesive sheet from said aggregate, and in that after step (a), the following step is carried out: burying part of said aggregates by heating in the adhesive layer of said adhesive sheet. In carrying out decorative finishing with a multi-colour pattern using various decorative aggregates having different shapes and colours, first, an adhesive sheet is covered with a release paper in which only the first aggregate loading portions are cut out, and the first aggregates are scattered on only the cut-out portions. Thus, by sequentially repeating this operation the required number of times, it is possible to obtain an aggregate sheet with the desired pattern. By use of such an aggregate loading sheet with a multi-colour pattern, it is possible to carry out the concrete finishing with the aggregates being exposed in the multi-colour pattern. By scattering aggregates, for example, decorative aggregates, of about 10 mm in size on an adhesive sheet, the aggregates are easily fixed to the adhesive sheet to the extent that the adhesive sheet can be carried. Further, by suitably selecting the kind of adhesive on the adhesive sheet and the thickness of the adhesive layer, it is possible to suitably bury aggregates in the adhesive layer by their dead weights through wholly heating the adhesive sheet and the aggregates loaded thereon. The degree of burying can be adjusted by selection of the kind of adhesive, the heating temperature, the heating time, etc. In addition, after loading aggregates on an adhesive sheet, the aggregates can be buried in the adhesive layer by pressing the aggregates while suitably heating it as needed. When mortar or concrete is placed on the adhesive sheet in which the aggregates are suitably buried, the mortar or concrete is made to flow over the surface of the aggregates and the adhesive layer, and it can perfectly cover the surfaces of the aggregates exposed from the adhesive layer. The aggregates are strongly bonded along with the hardening of the mortar or concrete. Preferably, the adhesive strength of the adhesive used is of such a degree that fallout of the aggregates loaded during the work is prevented, and further, it is preferably of such a degree that the adhesive sheet is easily separated from surfaces of the aggregates and mortar upon removal of the adhesive sheet after hardening of the mortar or concrete. When the adhesive strength is less than about 2N/cm, the adhesive sheet can be easily removed, but the aggregates are in danger of falling out during the work. For holding the aggregates in during the work, the adhesive strength is preferably more than 3N/cm. Even when the adhesive strength is in the region of 3N/cm or more in the dry state, since the mortar is applied together with a large amount of water, and further some water content tends to be present at the interface between the adhesive and the mortar even upon separate of the sheet, the adhesive sheet of such a type as is weak against water has a very much reduced adhesive strength. Further, since water gradually permeates at the interface between the aggregates and the adhesive, the adhesive strength at this portion is significantly reduced. Thus, even upon use of an adhesive sheet having an adhesive strength enough to endure the work, since the adhesive strength is reduced due to the action of water after the mortar or concrete is applied, it is possible to separate the sheet while leaving the aggregates in the mortar or concrete layer. This is one of the advantages of a construction method using the adhesive sheet. The method of carrying out aggregate exposed finishing for concrete using the adhesive sheet has the following further advantage: namely, in the prior art construction method, concrete as a substrate is first prepared, mortar mixed with decorative aggregates is placed on the concrete in a suitable amount, and the surface of the mortar is then washed away with water. On the contrary, in the method of the invention using the adhesive sheet, the mortar layer is not necessarily formed on concrete, that is, it is possible to prepare the aggregate exposed concrete by directly placing concrete so as to be contacted with the adhesive sheet surface in which the aggregates are buried. The construction method of this type is advantageous, particularly in directly forming exposed aggregates on vertical surfaces. Preferred embodiments of the invention will now be described in detail, with reference to the accompanying drawings, in which: Fig. 1 is a sectional view in the form of a flow chart showing one embodiment of a method of carrying out aggregate exposed finishing for concrete according to the present invention. Hereinafter, a method of carrying out aggregate exposed finishing for concrete according to the present invention will be described in detail by way of examples. In addition, the embodiments represent the preferred forms of the present invention, and therefore the present invention is not limited thereto. EXAMPLE 1 First, aggregates 3 were scattered on an adhesive layer 1 of an adhesive sheet with dimensions of 30 cm x 30 cm, the adhesive sheet being composed of the rubber based adhesive layer 1 and a plastics substrate 2. Thus, the aggregates 3 were stuck and loaded on the adhesive layer 1. Subsequently, the aggregate loading adhesive sheet was inserted in an electric furnace, and heated at 150°C for 15 min, so that part of the aggregates 3 was buried in the adhesive layer 1. The sheet was then removed from the electric furnace and cooled to room temperature, after which a mortar 4 of cement : sand 1 : 3 was placed on the aggregates 3. This was left at room temperature for two days after the application of the mortar. After that, the adhesive sheet was separated from the surface of the aggregates 3, to thus obtain a sample (30 cm x 30 cm) of aggregate exposed concrete. EXAMPLE 2 The aggregates were loaded on an adhesive sheet (30 cm x 30 cm) composed of a low viscosity rubber based adhesive in the same manner as in Example 1. The aggregate loading sheet was mounted on a hot plate at 100°C for 20 min, and the aggregates were pressed from the top so that part of the aggregates was buried in the adhesive layer. Subsequently, mortar was applied in the same manner as in Example 1. This was left for two days after application of the mortar. After that, the adhesive sheet was separated, to thus obtain a sample (30 cm x 30 cm) of aggregate exposed concrete. EXAMPLE 3 In the same manner as in Example 1, there was prepared a member in which aggregates were loaded and buried on an adhesive sheet (30 cm x 30 cm) composed of a rubber based adhesive. The substrate surface of the member thus obtained was stuck on a plate using a double faced adhesive tape. The plate was used as a framework of one wall surface for concrete casting while the aggregate loading surface was directed to the inside, and concrete was cast. The framework was removed after leaving for one week. At this time, the adhesive sheet was separated from the surface of the aggregates, together with the framework, to thus obtain a sample of excellent aggregate exposed concrete. As described above, by use of a method of carrying out aggregate exposed finishing for concrete according to the present invention, the problems of the prior art have been solved, or at least ameliorated. Thus, according to the present invention, it is possible to provide a method of carrying out aggregate exposed finishing for concrete capable of very much reducing the amount of aggregate used, and of facilitating the work without requiring long working times and high level techniques.

Claims: A method of making an aggregate exposed finish for concrete (4) using an aggregate loaded flexible adhesive sheet having adhesive properties such that the adhesive strength thereof is sufficient to retain the aggregate (3) before the hardening of mortar or concrete (4), and comprising the steps of: (a) loading aggregates (3) on an adhesive sheet (1,2); (b) applying mortar or concrete (4) onto an aggregate loading surface of said aggregate loaded adhesive sheet (1,2); (c) hardening said mortar or concrete (4); and (d) removing said adhesive sheet (1,2) to expose the aggregate exposed finish of the concrete; characterised in that: the flexible sheet is an adhesive sheet made of a heat-resisting substrate (2) and hot-melt adhesive (1) coated thereon, in that the adhesive strength decreases in contact with hardening mortar or concrete (4) to the extent of facilitating removal of said adhesive sheet (1,2) from said aggregate (4), and in that after step (a), the following step is carried out: burying part of said aggregates (3) by heating in the adhesive layer (1) of said adhesive sheet (1,2). A method according to claim 1 characterised in that step (b) includes casting mortar or concrete (4) onto the aggregate loading surface (1) of the aggregate loading adhesive sheet (1,2). A method according to claim 1 characterised in that step (b) includes press-contacting the aggregate loading surface (1) of the aggregate loaded adhesive sheet (1,2) with unhardened mortar or concrete. A method according to any one of claims 1 to 3 characterised in that before step (b), a substrate surface (2) of said aggregate loaded adhesive sheet (1,2) is fixed on a form; and after step (c) the form is removed, along with the adhesive sheet (1,2), to expose the aggregate exposed finish of the concrete. A method according to any one of claims 1 to 4, wherein the finish is a decorative finish using a plurality of different aggregates (3) having different shapes and/or colours, including the steps of: covering said adhesive layer (1) of the adhesive sheet (1,2) with a release paper having cut-outs corresponding to a required pattern of finish of a first aggregate (3); loading said first aggregate (3); repeating the above steps as many times as required with further, different aggregates (3) to build up said decorative finish; and carrying out said applying hardening and removing steps.

Inventors: ENOMOTO HIROYUKI, KOBAYASHI TERUAKI, OGAWA HIROYUKI, OYAMA MASAHITO, TAMURA YUTAKA, ENOMOTO, HIROYUKI, KOBAYASHI, TERUAKI, OGAWA, HIROYUKI, OYAMA, MASAHITO, TAMURA, YUTAKA, ENOMOTO, HIROYUKI, SLIONTEC CORPORATION, KOBAYASHI, TERUAKI, SLIONTEC CORPORATION, Ogawa, Hiroyuki, Seltec Corp., OYAMA, MASAHITO, SLIONTEC CORPORATION, Tamura, Yutaka, Seltec Corp.
Applicants: SELTEC CORP, SUGAWARA IND, SELTEC CORP., SLIONTEC CORPORATION
Application year: 1993
Main classification: B28B7
IPC codes: B28B19, E04F13, B28B11, B28B23