EP2540934A1

EP2540934A1 - A covering for formwork for concrete castings

Info

Publication number: EP2540934A1
Application number: EP12004372A
Authority: EP
Inventors: Matteo Mondelli
Original assignee: Proxital SpA
Current assignee: Proxital SpA
Priority date: 2011-06-27
Filing date: 2012-06-08
Publication date: 2013-01-02
Anticipated expiration: 2032-06-08
Also published as: EP2540934B1; ITMI20111169A1

Abstract

A covering (10) for formwork (22) for concrete castings (24) reinforced or not, for the realisation of building works positioned so as to cover the walls or inner surfaces of the formwork made of wood, plastic or metal, with said covering defined by a tape or sheet (12) suitable for being wound on a reel (14) from which it is unrolled and cut and comprising at least two layers of which one is of polyolefin material and one of expanded or foam material, respectively, suitable to support dilations and absorb the stresses and shrinkage of the concrete during the setting and subsequent hardening phase and to prevent adherence with the concrete casting (24).

Description

The present invention relates to a covering for formwork for concrete castings.
More in particular, the present invention relates to a covering for formwork for the realisation of building works in reinforced or non-reinforced concrete.
Formworks or moulds are used to realise building works in reinforced concrete and define the casings inside which the concrete casting is made in the liquid state and in which it remains until the end of the setting and hardening process; the casting remains inside the formwork or mould until its mechanical resistance is such as to guarantee absorption of the stresses to which the structure is subject immediately after the formwork or mould removal step.
The formwork or mould has a geometric function, in that it makes it possible to give the concrete casting the desired shape and, at the same time, has a mechanical function in that it must not deform and must sustain the pressure which the casting exerts on its walls and the vibrations of compaction; in addition, the formwork must ensure a tight seal avoiding the danger of leakages of material causing the formation of a casting with a spongy or gravel nest structure.
In order to favour the detachment of the formed concrete and prevent the same from sticking to the inner walls of the formwork with consequent drawbacks in terms of planarity, appearance and mechanical structure, the inner walls of the formwork must be covered with a layer of form release agent suitable for creating an insulating film between the formwork and the concrete; the specific chemical agents present in the form release agent assist the detachment of the cement paste from the surfaces of the formwork. Formworks or moulds may be made in various materials such as wood, polystyrene (ICF method- Insulated Concrete Form) or equivalent known plastic or metal materials; the chemical composition of the form release agent varies depending on the type of material the mould is made of.
Wooden formworks are characterised by their low cost and highly flexibility in terms of application and assembly. However, they have the drawback of being utilisable only a few times since over time the wood tends to become rigid, heavy and no longer transpires; moreover, the wood leaves an impression on the concrete which acquires the reverse pattern of the grains and knots with a consequent aesthetic limitation.
Another solution consists of using formworks or moulds made with ICF technology (Insulated Concrete Form) using polystyrene foam which, compared to those made in wood, ensures improved performance, increased versatility and reduced costs:
Formworks or moulds may also be made from metal so as to be able to be used over and over again and guarantee a particularly superior surface finish. However, such types of formworks have disadvantages related to the considerable costs and reduced flexibility of application caused by the fact that they cannot be shaped directly on site but must be pre-fabricated.
As said above, to favour the detachment of the artefact from the formwork the inner walls need to be covered with a form release agent, that is a emulsified or aqueous solution which as well as facilitating the detachment of the product, ensures a quality surface finish free of bubbles and the like.
However, the use of such form release agents is characterised by considerable costs, both with reference to the form release agent itself as regards the chemical composition, and with reference to the labour costs involved given that the form release agent must be applied manually and with particular care.
A further drawback is related to the complex and laborious removal operation of the layer of form release agent from the formwork or mould once the product has been obtained, so as to prepare the same for a subsequent use.
A further drawback is represented by the fact that with traditional formworks is it not possible to obtain products with particular surface finishes (for example, parallel lines, lozenges, squares etc) except by using ad hoc formworks.
Such drawbacks are also found in DE 29810121 which makes reference to an apparatus and method for the application of a drainage material to the surface of the casing of a formwork for concrete, with such draining material wound on a reel in an intermediate position in relation to a layer or film of adhesive material and to a layer or film of protective film, with the latter being removed at the moment of application.
The purpose of the present invention is to overcome the drawbacks mentioned above.
More in particular, the purpose of the present invention is to provide a covering for formwork for concrete castings which is easy, simple and fast to apply.
A further purpose of the present invention is to provide a covering for formwork which ensures easy detachment of the product from the formwork.
A further purpose of the present invention is to provide a covering for formwork which enables a high quality product in terms of surface finish to be obtained.
A further purpose of the present invention is to provide a covering for formwork suitable for ensuring limited costs.
These and other purposes are achieved by the covering for formwork for concrete castings of the present invention which comprises a tape or sheet with a multilayer structure, tendentially wound in a reel from which it is unrolled and cut to be positioned so as to cover the walls or inner surfaces of a formwork or mould made of wood, plastic or metal, to be filled with a concrete casting.
The construction and functional characteristics of the covering for formwork for concrete castings of the present invention will be more clearly comprehensible from the detailed description below in which reference is made to the appended drawings which show a preferred and non-limiting embodiment and wherein:

figure 1 schematically represents the covering for formwork for concrete castings of the invention;
figure 2 schematically represents a portion in cross-section of the covering for formwork of the invention;
figure 3 schematically represents a formwork provided with the aforesaid covering.

With reference to the drawings referred to, the covering for formwork for concrete castings of the present invention, globally denoted by reference numeral 10, is defined by a tape or sheet 12 wound to form a reel 14 from which it is unwound and cut to the desired length for the specific applications described further below. The tape or sheet 12 of the covering 10 is defined by a multilayer structure which comprises at least two and preferably three layers, a first layer 16 defined by an adhesive material such as to enable its attachment to the inner walls of a formwork or mould 22, a second layer 18 defined by a film in polyolefin material having the function of preventing adherence with the concrete casting 24 which fills the formwork 22 and an intermediate layer 20 defined by an expanded or foam material preferably but not exclusively of the polyolefin or polyethylene type able to support the dilations and absorb the stresses and shrinkage of the concrete during the setting and subsequent hardening process and to enable, combined with the second layer 18, the smoothing out of any discontinuities of the mould (such as the grains of the wood) .
In an alternative embodiment, and specifically in the case of a wooden mould, the first layer 16 defined by adhesive material may be absent; in such case the sheet 12 of the covering 10 is stapled to the formwork.
Moreover, the intermediate layer 20, if suitably moulded on its surface, enables the transfer to the concrete structure of predefined and regular surface effects having an aesthetic function or functional to the adhesion of plaster or the like.
The composition of the film making up the second layer 18 and the foam defining the intermediate layer 20 is defined depending on the specific use, on the type of formwork or mould and on the characteristics of the concrete.
The thickness of said layers is also scaled in relation to specific requirements; typically, but not exclusively, the thickness of the second layer 18 has a minimum value of 5 µm, while that of the intermediate layer 20 has a minimum thickness equal to 0.3 mm. With particular reference to figure 3, a formwork or mould 22 provided with the covering 10 of the invention and filled with the concrete casting 24 is shown in schematic form.
The inner walls of the formwork or mould 22 are "lined" with the covering 10; in particular, the first layer 16, defined by the adhesive layer, adheres to the walls or inner surfaces of the mould 22, while the second layer 18, defined by the polyolefin or polyethylene or other type film suitable for the purpose, is in contact with the concrete 24.
Once the covering of the walls or inner surfaces of the formwork or mould 22 is complete, it is assembled to receive the concrete casting. As may be seen from the above, the advantages achieved by the covering for formwork for concrete castings of the present invention are evident.
The covering for formwork for concrete castings of the present invention, makes it possible to cover the inner walls of the formwork whether made of wood, metal, polystyrene or other plastic material suitable for the purpose, simply, easily and rapidly.
A further advantage is represented by the fact that at the end of the setting and hardening process of the concrete, the covering which the invention relates to can be easily removed from the formwork, which is rapidly cleaned and reutilised.
The fact that by evenly covering the walls of the formwork the covering for formwork of the invention prevents any contact between said formwork and the concrete and, in the case of wooden formworks, prevents their rapid hardening and loss of transpiration consequently prolonging their useful life is of further advantage.
The fact that the covering for formwork of the invention, when applied to the wooden formwork, makes it possible to eliminate any characteristic grains which the mould transfers to the concrete casting, thereby ensuring a superior surface finish as well as a high quality appearance, is of further advantage.
A further advantage is represented by the fact that by being fast and easy to apply and remove, the covering for formwork of the invention does not requiring subsequent processing of the product in relation to the surface finish, making it possible to reduce production costs.
The fact that the covering of the invention makes it possible to give the product different surface finishes of the smooth type or with parallel lines, lozenges or other geometrical figures with both aesthetic and functional purposes to improve the adhesion of any subsequent plaster, is of further advantage.
Despite the invention having been described above with particular reference one of its embodiments, given solely by way of a non-limiting example, numerous modifications and variants will appear evident to a person skilled in the art in the light of the above description. The present invention therefore sets out to embrace all the modifications and variants which fall within the sphere and scope of the following claims.

Claims

A covering (10) for formwork (22) for concrete castings (24) reinforced or not, for the realisation of building works positioned so as to cover the walls or inner surfaces of the formwork made of wood, plastic or metal, with said covering defined by a tape or sheet (12) tendentially wound in a reel (14) from which it is unrolled and cut and characterised in that it comprises at least two layers of which one in polyolefin material and one in expanded or foam material respectively able to support dilations and absorb the stresses and shrinkage of the concrete during the setting and subsequent hardening process and to prevent adhesion with the concrete casting (24).
The covering for formwork according to claim 1, characterised in that the tape or sheet (12) comprises a further layer suitable for permitting attachment to the inner walls of the formwork or mould (22).
The covering for formwork according to the previous claims, characterised in that the further layer suitable for permitting attachment to the formwork is defined by a first layer (16) in adhesive material, the layer suitable to prevent the adherence of the concrete casting is defined by a second layer (18) composed of a film in polyolefin material and the layer suitable to support the dilations and absorb the stresses and shrinkage of the concrete is defined by an intermediate layer (20).
The covering for formwork according to one or more of the previous claims, characterised in that the intermediate layer (20) is defined by a material of the polyolefin or polyethylene type.
The covering for formwork according to one or more of the previous claims, characterised in that the thickness of the second layer (18) tendentially has a minimum value of 5 µm and the thickness of the intermediate layer (20) has a minimum value tendentially equal to 0.3 mm.
The covering for formwork according to one or more of the previous claims, characterised in that the intermediate layer (20) of the tape or sheet (12) has a surface with a flat extension.
The covering for formwork according to one or more of the previous claims, characterised in that the intermediate layer (20) of the tape or sheet (12) has a surface with a shaped extension.
The covering for formwork according to claim 1, characterised in that the sheet (12) of the covering (10) is stapled to the mould (22).