The present invention refers to a method to increase t adherence between a relatively glassy surface, e.g. a ste surface and a substance, e.g. mortar, concrete, grout, plast or the like, which can be applied on or around said surfa and which pourable and which solidifies to a rigid form.

BACKGROUND OF THE INVENTION

At many applications it is desired to increase the adherenc between e.g. a steel surface and one against this appliabl concrete or grout substance for example by means of a spray o a cast procedure. It may e.g. concern a thin concret construction which is too thin to be reinforced in an ordinar way by means of rounds for reinforced concrete or welded mes rein orcements .

According to a known method (Swedish patent application No 7908919-5) a form face is coated by a plastic material, for example a gelcoat, whereby short fibres or flocks are spraye on to the plastic material, whereby the fibres are raised b electrostatic charging. When the gelcoat has cured concrete i cast against it. The gelcoat forms an integrated layer wit the concrete and when this has cured the form face will b removed. In this method the form face do not constitute an part of the completed product.

It is also known to use a form part or a form face as a rein forcement inside a construction which has a thin wal

( DE-875. 03 ) , and to which form face anchor elements ar connected, which are cast into the construction part. In cas the form face consists of a sheet of steel, the. ancho elements must be welded, which at large surfaces, such as e.g. floor slabs is a very extensive and expensive work. A method is also known at which the reinforcement consists of a sheet, which at one side and the end sides is intended to encompass a concrete slab. The sheet may e.g. be formed as a box or

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consists of a pan of galvanized sheet of steel, in which th concrete mass is cast. The pan thereby constitutes the tensil reinforcement of the concrete slab. Until now it has not bee possible to join the sheet and the concrete mass, in such way that the sheet of steel can act as a rein orcement, i spite that one has tried to give the sheet such a roug surface as possible, or has provided it with corrugations disintegrations or elevations of other kinds. Also differen tongues of hobbings and punching of tongues, which are folde against the concrete mass, has not been enough to give th necessary adherence to make it possible to contemplate th sheet as an integrated unit together with the concrete sla and which is able to carry occuring extension strains.

THE OBJECT OF THE INVENTION AND ITS MOST IMPORTAN CHARACTERISTICS

The object with the present invention is to provide a metho to increase said adherence in a simple and a relatively chea way without that the glossy surface being exposed t deformations or weakenings, and which adherence should b accomplished on even surfaces as well as on single or doubl curved surfaces and also in recesses which- are difficult t access. These objects have been solved by that the gloss surface which has been provided with a glue coat or the lik is coated in an electrostatic way, alternatively is coate with artificial fibres, so-called fibre flocks, which ar raised from the surface, covering an essential part of it surface, whereby the wet mass is applied to the fibre flock.

DESCRIPTION OF EMBODIMENTS

Practical tests have shown, that an excellent adherenc between a relative glossy surface such as a galvanized shee of steel or a smooth plastic surface and e.g. a green concret mass may be obtained if the glossy surface is coated wit so-called fibre flock, i.e. with raised artificial fibres, which are brought to the glossy surface in an electros t-i

way, by that the surface has been coated with a glue layer first, whereby the fibres are located closely to each oth raised in the glue layer. The green concrete mass is suck into the fibre flock layer and into every single fibre means of the capillarity and a very unexpected stro adherence is thereby obtained, which results in that it h been possible to produce very thin concrete beams, with thickness of only about 25 mm, and these beams are handl during the manufacturing, the transportation and the mounti without that the slab show any tendency to crack.

A further object, where the increased adherence will useful, is as an underlayer at grouting of e.g. ste constructions and to increase its fire resistance, whereby th grout or mortar mass may be applied by spraying (e.g guniting). The method according to the invention may also b used at manufacturing of phasade or mounting base elements, a manufacturing of floor structures and so on.

In cases where the mass used includes limestone or cement it is recommended to use alkali resistant fibres.