IL99381A - Method for building ceiling structures and structures made by said method - Google Patents

Description

REF 1929/91 IT ni METHOD FOR BUILDING CEILING STRUCTURES STRUCTURES MADE BY SAID METHOD 1929/91 METHOD FOR BUILDING CEILING STRUCTURES AND STRUCTURES MADE BY SAID METHOD Field of the Invention This invention relates to a method for building ceiling structures and to the structures made by said method. It particularly refers to such structures which comprise a reinforced concrete slab, and the lowermost portion whereof is made of or comprises a pre-fabricated plate or sheet of a suitable material.

Background of the invention In the building art, various methods are used for making suitably finished and decorative ceiling surfaces. These methods include, for instance, making said surface by hand, by applying and finishing a smooth surface coating, this obviously being a procedure that is expensive and time-consuming, since its requires working overhead, on a structure that is above the workers' head. Alternatively, it is known to use prefabricated plates or sheets of a suitable material which are attached to the lowermost portion of a slab by means of profiles which permit to arrange the various plates in matching relationship on a horizontal plane, screws or the like being used to secure the plates to the profiles and the profiles to one another and to the slab. This is also a time-consuming procedure, for the reason set forth above. 1929/91. 099381/2 In Israeli patent No. 96237 of the same applicant a reinforced concrete slab structure is described which comprises lowermost plate or sheet components in ab utting relationsh ip, essentia l ly defining a ceiling surface, a nd inserts in the body of the concrete, wherein said inserts are adhesively connected to sa id plate or sheet components, preferably at limited, separate areas, whereby to support the same. The inserts may be m ade of porous material or have the shape of profiles incorporated in the body of the concrete; and may be provided w th downwardly projections and be adhesively connected to the plate components at the said projections. The said patent also discloses a process for making such a slab, which comprises making a form for casting the concrete, providing plate components which are either the bottom of the form or are supported on such bottom, adhesively connecting said plates to inserts located above the same, placing the reinforcements of the concrete, and casting the concrete -various operations taking place in any convenient order. The form for casting the concrete further comprises lower support elements, e. g. made of wood, on which the plate components are supported, and the process comprises removi ng said support elements after the concrete has hardened. The plate components m ay be adhesively connected to the inserts before or after making the form and placing them in thei r position therein, and the rei nforcements or pa rts thereof m ay be put in place at a ny ti me, e.g. before adhesively con necti n g the i nse rts to the plate com pone n ts. 1929/91 It is a purpose of this invention to provide a method for making a ceiling structure which eliminates all the drawbacks of known structures and affords a considerable saving of time, being therefore inexpensive.

It is a purpose of this invention to provide a method for making reinforced concrete slabs, particularly slabs the lower surface of which constitutes a ceiling, which is quicker and more economical than any methods hitherto known, and affords a saving of raw materials and of labour, while achieving results that are completely satisfactory from a structural and an aesthetic point of view.

It is a further purpose of this invention to provide a ceiling structure, which results from the application of the aforesaid method, and which provides a well finished and decorative ceiling surface.

It is a further purpose of this invention to provide such a structure which has a high resistance.

Other purposes of the invention will become apparent as the description proceeds.

Summary of the Invention The purposes of the invention are achieved by means of a process which comprises making a form for casting the concrete, providing plate components which are either the bottom of the form or or are supported on 1929/91 99381/2 such bottom, distributing an adhesive on predetermined portions of the upper surfaces of said plate components, placing the reinforcements of the concrete, and casting the concrete - the said various operations taking place in any convenient order.

The portions of the upper surfaces of the plate components, on which the adhesive is distributed, must have a sufficient overall area as to provide the desired adhesive bond strength and be so distributed that the adhesive bond be present in a sufficiently uniform manner over the various sections of the slab and of its bottom surface which constitutes the ceiling. Said portions are predetermined according to these requirements. In principle, the entire upper surface of the plate components could be overlaid with adhesive, but this is generally unnecessary and would be wasteful. The area of the upper surfaces of the plate components which is to be overlaid with adhesive will generally vary between 5% and 100% of the overall area of said surfaces. While in various cases substantially less than 100% of the area needs be overlaid with adhesive, it may be convenient, particularly for mass and automated production, to overlay the whole area of the surface with adhesive, for the sake of simplicity of operation. Of course, unnecessary and redundant amounts of adhesive applied can be dispensed with, as desired.

In a variant of the invention, the form for casting the concrete further comprises lower support elements on which the plate components are supported, and the process comprises removing said support elements 1929/91 " " 0 9 9 3 8 1 / 2 after the concrete has hardened. Said support elements may be preferably made of wood.

The adhesive to be employed can be any adhesive suitable for bonding paper in general to concrete. Examples of such adhesives, which are well known to persons skilled in the field of building, are, e.g. Edex (Shachal, Israel), which can be mixed with fine and clean sand, according to the instructions of the manufacturer, and depending from the temperature, humidity, etc. Other examples of suitable adhesives are B.G. Bond (B.G. Bond, Israel), and Acrytit (Shachal, Israel), and in general polymeric binders mixed with aggregates..

The ceiling structure according to the invention comprises a reinforced concrete slabs and plate components, the bottom surface of which constitutes the ceiling surface, and the top surface of which is adhesively connected, at predetermined areas thereof, to the concrete body of the slab.

Description of the drawings The invention will be better understood from a description of preferred embodiments thereof, with reference to the attached drawings, wherein: Fig. 1 is a vertical cross-section of part of a ceiling structure according to an embodiment of the invention; 1929/91 99381/2 Fig. 2 is a perspective view of a form for casting the concrete in carrying out the method according to an embodiment of he invention; and Fig. 3 is a vertical cross-section of a detail of the form of Fig. 3.

Detailed Description of Preferred Embodiments With reference now to Fig. 1, numeral 10 generally designates a structure according to the invention, a part of which is seen in vertical cross-section in the figure. Said structure comprises a body of concrete 11, reinforcements 12 and plates or sheets 14. The reinforcements are symbolically shown as comprising iron rods, a wire net and ties 13, but they are not a part of the invention and may be of any kind desired. It will be understood that no limitation whatsoever is involved in the invention with respect to the type of reinforcements used. The slab may comprise inserts of any desired kind placed in the concrete and made of any convenient material, such as that known as Ytong, or may comprise other structural elements, not shown as they are optional and conventional The lowermost portion of the slab structure, illustrated in Fig. 1, is constituted by plates or sheets 14, which provide the outer surface 15 of the ceiling without the need of any finishing operations. However such operations may be carried out, if desired, without departing from the invention. The plate 14 is adhesively connected to the body of the concrete at selected, predetermined areas 15. 1929/91 99831/2 The adhesive connection preferably does not cover the entire contact surfaces between the plates and the concrete, but is limited to separate areas of said surfaces, calculated so as to provide the required resistance of the bond.

Gypsum, as has been said, is a preferred material for the plates 14. Any other desired material, however, can be used in carrying out the invention, e. g. cement or asbestos boards.

An embodiment of the method according to the invention, which provides the structure described, is illustrated in Fig. 2. A form for casting the concrete, generally indicated at 20, is prepared. It is conveniently made of wood or metal or other materials employed in conventional concrete forms and comprises vertical partitions 21 and a bottom 22. The form is usually supported, as in conventional concrete casting, on temporary supports provided for this purpose, which are later disassembled. These are not illustrated as they are entirely conventional. The plates 14 rest on the bottom 22 of the form. Sealing strips 23 (not shown in Fig. 2) are placed at the contact zones 16 between adjacent plates 14, as shown in Fig. 3, which is a cross-section of a fragment of Fig. 2 taken along the plane III-III of Fig. 2. This has the purpose of preventing seepages between adjacent plates 14, which would damage the appearance of the finished ceiling.

Other means for preventing seepage may be adopted. The reinforcement, which can be of any desired type, as in generally the case in carrying out the invention, is not shown in Fig. 2. 1929/91 9938 In carrying out the process according to the invention, the form 20 is built in a conventional manner. Next, the plates 14 are overlaid with adhesive at the predetermined areas and are placed in it. For ease of operation, one would normally prefer to employ an adhesive which is dried before the plate is handles and the concrete poured. However, depending on the adhesive employed, it may be necessary or preferable in some cases to utilize the adhesive in wet form. The reinforcement is put in place and concrete is poured until it reaches a predetermined level. The concrete is allowed to set, and finally the form 20 is stripped from the resulting slab.

In Fig. 2 the form is provided with a bottom 22, because it is assumed that the plates 14 are not strong enough to support the weight of the concrete. This is the case of gypsum plates. If another material should be used, w hich is strong enough not to require a bottom support, t is latter could be be omitted. This might be the case if metal plates were used.

It is surprising that a strong adhesive bond is obtained by the process hereinbefore described. It was to be expected that the water and chemicals content of the crude concrete, the reactions which take place in its curing, and the heat that is developed, would have prevented the formation of such a bond. On the contrary, the applicant has determined that the bond is very strong. Tests have been carried out by the inventor which show the surprising structural strength obtainable by the process and the structure of the invention. In all cases tested, in which a load was applied to the structure, never was it possible to separate the concrete from the plate at the bond, and in all case the structure failed at other places. When a load 1929/91 equal to 140 times the weight of a gypsum plate, failure of the structure took place at the connection of the paper with the gypsum, and the paper-concrete bond remained substantially intact.

While preferred embodiments of the invention have been described by way of illustration, it will be understood that they involve no limitation and that the invention can be carried out in many ways and with many adaptations and modifications, without departing from its spirit or from the scope of the claims. 1929/91 99381/2

Claims (1)

1. CLAIMS 1. Process for making a reinforced concrete slab, defining a ceiling, which comprises making a form for casting the concrete, providing plate components in the form distributing an adhesive on predetermined portions of the upper surfaces of said plate components, placing the reinforcements of the concrete, and casting the concrete - the said various operations taking place in any convenient order. 2 - Process according to claim 1, wherein the portions of the upper surfaces of the plate components, on which the adhesive is distributed, have a sufficient overall area as to provide the desired adhesive bond strength and are so distributed that the adhesive bond be present in a sufficiently uniform manner over the various sections of the slab and of the ceiling which constitute s its bottom surface. 3 - Process according to claim 1 , wherein the area of the upper surfaces of the plate components which is to be overlaid with adhesive is comprised between 5% and 100% of the overall area of said surfaces. 4 - Process according to any one of the preceding claims, wherein the adhesive to be employed is a polymeric adhesive. 5 - Process according to claim 1 , wherein the plates are made of gypsum. 1929/91 99381/2 6- Process according to claim 1, wherein the form for casting the concrete comprises lower support elements on which the plate components are supported, and the process comprises removing said support elements after the concrete has hardened. 7 - Process according to claim 6, wherein the plate components are the support elements of the form for casting the concrete. 8 - Process according to claim 6, wherein the support elements are made of wood or metal. 9 - Process according to claim 1, comprising providing sealing means at the contact lines between adjacent plate components, such as sealing strips superimposed thereto. 10 - Process for making a reinforced concrete slab structure, essentially as described and illustrated. 1 1 - Ceiling structure, comprising a reinforced concrete slab and plate components essentially as described and illustrated, the bottom surface of which constitutes the ceiling surface, and the top surface of which is adhesively connected, at predetermined areas thereof, to the concrete body of the slab. 12. Reinforced concrete slab structure, essentially as described and illustrated. Rv :