ARRANGEMENT FOR LAYING CONCRETE FLOORS

Abstract: Arrangement for casting concrete floors against a hardened base with the aid of surface vibrators for levelling and vibrating the concrete. The arrangement consists of screed guides for these surface vibrators. The screed guides are designed in such a way that their cross-section is I-shaped. The upper horizontal surface serves as a slide face for surface vibrators (1). The lower horizontal surface series as a support against the base material (2). The beam web is provided with holes for dowels or other connecting devices (4). The beam web is also provided with brackets which can carry the reinforcement material for the concrete (3). The invention also includes reinforcing the above-mentioned beams by means of welded mesh reinforcement of metal and/or glass fibres. The latter can, but need not necessarily be, of alkali-resistent glass. The invention also embraces a method for using the above mentioned arrangement. This method entails using the beams as permanent formwork, i.e. the beam is not removed after the concrete has hardened.

Description: Arrangement for laying concrete floors The present invention refers to an arrangement and a method for using this arrangement for laying concrete floors on a hardened base. Attempting to find aids and methods, for more rational construction is in every way a worthy aim. The proce¬ dure adopted for laying concrete floors against a hardened base, for example in factories, department stores, bridges, concrete floors in multi-storey build- ings etc, is in principle as follows: The surface on which the concrete floor is to be laid is divided, if possible, into rectangles of equal size. Half of these, distributed in a chessboard pattern, are laid the first day and the remainder are laid the second day. The reason for this is that the sides bounding these rectangular sections must be used as a screed guide support for the apparatus which is used for levelling and vibrating the applied concrete. Every second section must be given sufficient time to harden before the adjacent sections can be treated in the same way. The arrangement forming boundaries for the sides of the rectangular sections also act as barriers for the freely running concrete. Before these guide supports are placed in position, certain preparatory work must be carried out. This consists of searching for a suitable material for use as a base for the concrete. The choice of base material is particularly important in, for example, factory buildings with large areas which can be subjected to considerable loads. Sand, which is an easily worked material with satisfactory drainage properties, is often used as a base on which the screed guide supports can be placed so that they are horizontal. When the screed guides are in position, concreting can be carried out in the first-day rectangles, as described above. The concrete is poured in the rectangle in question and is levelled oϋf manually. A light vi¬ brating screed is then used for distributing and vi¬ brating the concrete. This screed is supported ori the screed guide supports which have been set up. When all the first-day rectangles have been processed in the manner described above, work is stopped to give the concrete time to harden until the next day. The same screed guide supports can be used on the following day for proceeding in an analogous ' manner. When this work has been carried out, the concrete is permitted to harden until it has achieved sufficient strength to allow the screed guide supports to be removed. The voids thus created must be filled with concrete. This must be permitted to harden before the final treatment of the floor can be started. Such treatment normally embraces grinding and/or filling. Painting or other surface finishing treatment is then usually applied before the floor is taken into use. This procedure for producing floors does not tally with the aim of rationalizing constructions. The present invention describes an arrangement and a method for avoiding the following troublesome disadvantages which result from the method described above. Taking two days for. concreting is a serious short¬ coming in the method which is used today. The need _OMPI_ I to remove the screed guides and fill the voids which they leave with concrete also constitutes disadvantages. The German published patent application No. 1684389 indicates one means of avoiding this disadvantage by using the reinforcement in the floor to be cast as screed guide supports for the levelling screed. The disadvantage of this method i-s obvious since metallic objects very easily corrode. This will occur if the method is used and is probably the reason why it has never been generally accepted. It is, in fact very seldom used. Swiss patent No. 545 393 indicates a means of placing prefabricated beams in a grind pattern so that the beams can be used as supports for concrete distributing machines of a type similar to that described 'aBove. This method has also been unsuccessful in gaining general acceptance on the market. It is easy to understand why since the beams are heavy and difficullt to handle. The concrete involves a considerable weight in itself and to this must be added the weight of the reinforcement used in the beams. A further disadvantage is that the- welded mesh reinforcement, which is usually placed in the concrete to increase the loadbearing-- capacity of the floor, cannot be fixed in position in a satisfactory manner. Another shortcoming which affects the current system is that it is difficult to place reinforcement which runs through the various rectangles with the purpose of preventing vertical movements in the finished floor. The present invention indicates an arrangement which makes it possible to obtain a rationally produced OMPI floor and which completely, eliminates the shortcomings-, mentioned above in the methods currently used for laying floors; the invention also includes instructions for avoiding the shortcomings inherent in the methods presented in the abovementioned patent documents. Figure 1 facilitates an understanding of design and mode of use of the present invention. Figure 1 consists of a cross-section of a lpadbearing beam. Light vibrat¬ ing screeds are run on at least two such beams. The purpose of these screeds is to level and vibrate the concrete which is used in producing the floor. Two such beams are normally used. The other two sides of the abovementioned rectangles can consist of conventional material such as wood planks, concrete walls or the like or of beams of the type referred to in the present invention. One of the advantages offered by this procedure is that dowels -can be used and that welded mesh reinforcement can be fastened to the protruding brackets on the beam web. The design of the cross- section presented in Figure 1 constitutes one example of several possible different designs. The figure indicates that the surface, which is in¬ tended to provide a slide face for the light vibrating screed (1), is made sufficiently wide to ensure that the screed is carried in a reliable manner. Surface (2) , which rests on the base, should preferably be designed in such a way that a sturdy anchorage can be obtained. Vertical holes can, for example, be made in the flanges of this surface so that bolts or screws, for example, can be used for fixing the beam securely to the base. (These holes have not been indicated in the figure.) Horizontal holes can be made to take through-going dowels and thus connect two adjacent rectangular sections to concrete. The advantage obtained from this is that the risk of any movements between the sections is reduced. Welded mesh reinforcement, for example, can be placed on the brackets located on the web so as to increase the strength properties of the floor. The horizontal hole (3) can also be placed on or just below the top edge of the bracket projection on the beam web. If a beam of the type described above is to be used for the purpose for which it is intended, it must have considerable strength. The beam must be capable of with¬ standing impacts. This is more important than the requirements for co pressive or tensile strength. Impact resistance can be achieved by selecting " a suitable reinforcement. Experience has shown that the desired impact resistance cannot be obtained solely through the use of metallic reinforcement of conven¬ tional type. Welded finely meshed reinforcement must be used and the concrete must also be reinforced by means of glass fibres. These glass fibres need not necessarily be of alkali-resistent type (alkali- resistance being normally required for avoiding a - • reduction in strength in'concrete of considerable age). This will be obvious from the description to be pro- vided later of the method proposed here. It is, how¬ ever, an advantage if alkali-resistent glass fibres are used. The beam described above is used in a way which is already well known but the difference involved here is that the material is of such a nature that the beam can remain in position after the work has been carried out. Any risk of corrosion is completely eliminated, particularly if care is taken in anu- O facturing the beam to ensure that the metallic re¬ inforcement does not come too near the surface. Consequently, it is not necessary to move the screed guide support, as is usually the case. This means considerable gains in time and, therefore, in cost. Nor is there any longer any obstacle to concreting the entire floor in one day. This entails a marked reduction in the time required.

Claims: Patent Claim, An arrangement for casting concrete floors against a hardened base with the aid of surface vibrators for levelling and vibrating the concrete characterized by the fact that the surface vibrator is carried on screed guides which consist of longitudinal members with a cross-section design such that the upper horizontal limiting surface constitutes a slide face for surface vibrators or other levelling devices and that one or both of the vertical limiting surfaces is/are fitted with brackets on which various types of reinforcement can be fastened and that holes are made with unequal or equal spacing for dowels or similar connecting devices between both sides of the screed guides and that the screed guides are manufactured of concrete reinforced with mesh reinforcement and/or glass fibres.

Inventors: JOHANSSON L, LJUNGKVIST S
Applicants: JOHANSSON L, LJUNGKVIST S, MARIESTADS BYGGPRODUKTER HB, VM PRODUKTER SKOEVDE AB
Application year: 1981
Main classification: E04B5
IPC codes: E04F21, E04G21