EP1420128B1 - Concrete surface and its method of production - Google Patents

Abstract

Concrete surface (1), especially for floor, has barrier layer (3) over foundation (2) to be covered by concrete surface layer (4). The barrier layer has number of raised sections (5) and/or recessed zones (6), to give it variable thickness. The covering layer is a concrete which does or does not incorporate fibers. The barrier layer is a structured sheet or film and especially of plastics or metal which repels water or is watertight.

Description

The present invention relates to a concrete surface, in particular a concrete floor, according to the preamble of claim 1 and a method for its production according to the preamble of claim 12.

In the production of monolithic, integrally formed concrete floors occurs when setting and drying process of the concrete due to the volume decrease to an uncontrolled crack or joint formation, especially in the case of concreting large areas.

The prior art attempts to counter this undesirable property of the concrete in different ways.

Currently, it is assumed that the best prevention of (shrinkage, setting) cracks for monolithic concrete floors is that you first between the base layer (= base) and the concrete (= top layer) a sliding layer in the form of a plastic film provides, that is, the concrete layer is applied to an arranged on the substrate plastic film, and that then (generally the day after concreting) so-called "dummy joints" cuts into the surface of the concrete layer, generally at a mutual distance of about 5 up to 7 m. This ensures that the occurring in each case concrete shortening occurs as a result of setting or drying controlled in the dummy joints to light and no uncontrolled cracking or jointing occurs between them. Similarly, it is avoided by inserting the plastic film that the water in the fresh concrete escapes uncontrollably into the ground. This method is not efficient in that the day after concreting still joints must be cut into the concrete, and also the joints then sealed or sealed and later mostly have to be rehabilitated. Furthermore, this method makes high demands on the flatness of the wing or the substrate, since the plastic film otherwise can not slide, but this is necessary to counteract the shrinkage or shortening of the concrete during setting or drying.

It has also been proposed to counteract the formation of (shrinkage, setting) cracks during setting and drying of the concrete by incorporating special plastic fibers of specific dimensions into the concrete mass (see, for example, European Patent EP 0 448 577 B1) Company Danaklon A / S or its German equivalent DE 689 10 533 T2). However, this method is only slightly effective, especially for large areas. Furthermore, the homogeneous distribution of the fibers over the concrete mass is not always easy to achieve. The practical experience with this method is also very limited.

EP-A-0 808 712 discloses the insertion of an absorbent or water-absorbing separating layer between the substrate and concrete mass using concrete mixtures which have a high excess of water. Water is absorbed in the separation layer and subsequently released in time to avoid cracking.

The object underlying the present invention is to provide a method of the type described above, which at least partially avoids the disadvantages of the prior art.

A further object is to provide a method for producing a concrete surface, in particular a concrete floor, in which the formation of uncontrolled cracks due to setting or drying of the concrete is largely avoided or at least controlled.

Yet another object is to provide a method for producing a seamless concrete surface, in particular a seamless concrete floor.

The subject of the present invention is thus a concrete surface according to claim 1.

The term "concrete" as used in the invention is to be understood as being very comprehensive and includes both concrete in the actual sense and concrete-like hydraulic binder of all kinds, such. As cements, mortar or the like.

The term "concrete surface" in the context of the present invention includes concrete surfaces of any kind, both flat and uneven surfaces. In particular, these are concrete floors of any kind to understand.

One of the peculiarities of the concrete surface according to the invention, in particular concrete floor, must be seen in that the separating layer has a plurality of elevations and / or depressions, so that the thickness of the concrete top layer varies. This means that the separating layer has different thickness ranges in repeating, preferably regularly recurring sections. As a result, the thickness of the concrete cover layer thereby varies over the elevations or depressions of the separating layer, as described in more detail below.

As will be explained in more detail below, the use of a release layer of the type described above, inter alia, to avoid uncontrolled joint or crack formation in the concrete surface, in particular concrete floor, or at least causes the formation of controlled (micro) cracks or (micro-) ) Joints in the concrete, in particular cracks or joints less than 0.2 mm wide, which are harmless from a structural point of view. Without wishing to be bound by any particular theory, the effect of the release layer provided according to the invention may possibly be explained by the fact that the release layer absorbs or evenly distributes the shrinkage forces occurring during drying of the concrete, cement, mortar or the like of the cover layer over the surface and optionally leads to the formation of controlled (micro) cracks or (micro) joints. This will be explained later. In this way, according to the invention, the provision or cutting of (dummy) joints, as required in the prior art, can be avoided.

According to the invention it is preferred if the elevations and / or depressions are regularly distributed or arranged distributed over the separating layer. In this way a maximum effect is achieved.

In general, the separating layer has a structured, preferably uniformly structured surface. By way of example, the separating layer may have frustoconical or truncated pyramidal elevations (for example in the form of bumps, knobs, etc.), preferably in a uniform distribution.

The release layer provided according to the invention may in particular be a preferably structured foil, in particular plastic or metal foil, or a preferably structured sheet. According to the invention, it is preferred if the film is water-repellent or waterproof, since it then additionally fulfills a sealing function. Examples of plastic films suitable according to the invention are structured (eg knobbly) polyolefin films (for example polyethylene or polypropylene films), such as are commercially available, for example. The separating layer provided according to the invention may, however, in particular also be a preferably structured or profiled (eg deep-drawn) metal sheet ("profiled sheet").

According to a particular embodiment of the present invention, the separating layer can be formed by the substrate or the separating layer can simultaneously form the substrate.

Depending on the application, the thickness of the cover layer can vary over the elevations or depressions of the separating layer in many areas. In general, the thickness of the covering layer over the elevations or depressions of the separating layer varies on average by at least 5%, in particular by at least 10%, preferably by at least 15%, preferably by at least 20%, particularly preferably by at least 25%, very particularly preferably at least 30%. In other words, this means that the (average) thickness of the concrete topcoat due to the peaks or valleys varies by the aforementioned values, i. H. so shortened over the surveys and thickened over the wells.

Fibers, in particular plastic fibers, such as polyolefin fibers (eg polyethylene or polypropylene fibers), metal fibers, glass fibers or the like, may be incorporated into the concrete of the cover layer for various purposes be. The material, the nature, the quantity and the dimensions of such fibers depend on the particular application and are familiar to the person skilled in the art. Thus, for example, metal or glass fibers serve as a bar steel or reinforcing steel reinforcement replacement, plastic fibers are used for purposes of fire protection or for additional absorption of forces from setting and early shrinkage, etc.

Similarly, it is possible in the concrete of the top layer z. As steel inserts, Moniereisen etc. bring, d. H. to form the concrete as reinforced concrete or the like.

The concrete surface according to the invention, in particular concrete floor, is suitable both for indoor and outdoor use, in particular for large floor areas (eg hall floor, roadway floor, runway for aircraft or the like). The concrete surface according to the invention, in particular concrete floor, is generally resilient, in particular passable.

In general, the concrete surface according to the invention, in particular concrete floor, poured, in particular cast in one piece, and is preferably formed monolithic and joint-free.

The inventively provided, a plurality of elevations or depressions having separating layer (eg., "Noppenfolie" or "knobbed plate" made of plastic or metal, a profiled or deep-drawn sheet, etc.) should, among other things, in each case to divide the incoming shortening of the concrete into as many as possible, safe to use, controlled or controlled (micro) cracks or even completely suppress the cracking. The separating layer (eg dimpled foil or plate) causes a quasi "gearing" with the substrate (the concrete of the cover layer or cover plate thus remains essentially in the same place, ie displacements should be deliberately avoided.), And on the other hand The protruding into the concrete surveys ("pimples") or depressions act as a kind of "crack indicator" or "crack initiator" (The total thickness of the concrete is weakened locally, which in these "weak points" due to the increase in voltage primarily micro or predetermined cracks occur.). Theoretically over long distances trained restraints due Concrete shortening are thus divided into many small forces. Optionally, certain fiber additives (plastic fibers such as polyolefin fibers, eg, polypropylene fibers, or metal fibers, such as steel fibers, or glass fibers) can control these forces independently of the fundamental dimension of the release layer. Ideally, it is therefore independent of the size of the concrete surface to be concreted (eg in the case of large areas such as hall floors, airfields, etc.).

Without wishing to be bound by any particular theory, the present invention may be described by the following principles:

With regard to the residual stresses of the concrete, the following can be stated: If one wants to become independent of the dimension of the surface, one must forget all components which cause local movements or in which medium dimensions are considered (dummy joints). In order to achieve this situation, one must be able to bind all locally occurring stresses locally, before they accumulate each other and reach dimensions that are no longer manageable. However, this can only be achieved via the detour of the teeth to the ground. Thus, flat films which have too small coefficients of friction can not be used according to the invention.

By providing a multi-ply release layer (eg, a dimpled foil or plate) between the substrate and the concrete of the cover layer, this release layer prevents local shrinkage from being summed over greater distances. For example, it can be assumed that the temperature coefficient α = 10 ^-5 only takes effect on the locally limited area (eg 5 × 5 to eg 15 × 15 cm); Theoretically, it is possible to recalculate the permissible crack widths (eg: 0.2 mm) with the expected temperature gradient and shrinkage. The big advantage of this is that you no longer need to view a test field two-dimensionally, but that one dimension is sufficient (eg: 1 x 30 m).

With regard to the load voltages, the following can be stated: Since in the concrete surface according to the invention, in particular concrete floor, the joints eliminated, remain in the end only the tensile stresses on the underside of the plate (center of the field). In common consideration with the separating layer provided according to the invention (eg "dimpled foil / plate"), it can even be assumed under local loading that no real tensile stresses develop at the "underside" of the separating layer, but rather a kind of miniature vault. This is all the more true if the projections or depressions ("nubs") are less load-bearing than the separating layer as such.

The concrete surface according to the invention, in particular concrete floor, is thus based - in contrast to the conventional production of monolithic or one-piece concrete floors (eg steel or fiber concrete floors), in the between support layer (substrate) and structural concrete (cover layer) a sliding film to allow shrinkage movements on the fact that the concrete is given no possibility to sum up the unavoidable shrinkage movements over longer distances. This is achieved by a special separating layer interposed between the base layer (subgrade) and structural concrete (eg "dimpled foil" or "profiled sheet"), which hinders these movements during the setting process of the young concrete in the module of the dimpled spacing and keeps occurring forces in dimensions. which are either absorbed by the respective strength state of the composite concrete or in the case of exceeding this strength compensates for the movements in the form of many small, physically acceptable and therefore harmless cracks. As described above, the material of the release layer ("dimpled foil" or "profiled sheet") from plastic to deep-drawn sheets may actually include all materials that are stiff enough to resist the young concrete with some resistance to movement. The geometric shape of the dimpled films is similar to a drainage film, in which from a plane (possibly in the grid-shaped module) surveys, for example in the form of z. B. truncated cone or truncated pyramidal humps, knobs, cones or the like, stand out. Such dimpled sheets are commercially available. The mode of action of these nubbed foils is then that on the one hand against the substrate (base layer) a (higher) static friction is built, on the other hand on the top of the individual knobs weaken the (plate) thickness or thickness of the concrete of the top layer and thus small-scale harmless cracks provoke.

Without wishing to be bound by any particular theory, the static action of the end product may possibly be explained as follows: If floors are made without joints, the tensile stresses occurring at the top of the concrete surface at the joints will fall away from external loads (eg known and common design methods of bedded plates are referenced.). Tensile stresses from constraining forces (shrinkage, creep, temperature, etc.) essentially only remain on the upper side of the concrete surface, the deformations of which are compensated in the manner of many microcracks. The (load) tensile stresses occurring at the bottom must be absorbed with the help of the residual body (within the dimpled foil) of the concrete - possibly with the help of the composite cross-section of the concrete with the dimpled foil. If the load is above a nub ("weak point", ie lower concrete thickness), then the transmission of the forces as in a vault (support arch) within the concrete into the tension zone is accomplished. The geometric shape of these nubs and the relative height of the "peak" of these knobs to concrete slab thickness must ensure that no splitting effect or punching of the concrete is caused. The thus provoked, interspersed by microcracks concrete product can safely for the design of a lower, d. H. So have a lower modulus of elasticity than the uncracked concrete.

Further advantages of the concrete surface according to the invention, in particular concrete floor, can be summarized as follows:

With favorably chosen dimensions of the structured separating layer ("dimpled foil"), this can be easily overlapped when laying at the joints; when introducing the concrete, this gearing is secured by its own weight.

The potential static interaction between structured release layer ("bubble wrap") and concrete can reduce the structural strength of the concrete. If the module of the nubs is tuned to prefabricated reinforcement units (eg structural steel mesh mats), then this mat can easily be lowered or inserted therein in a correct position; Normally, the corrosion protection of the optionally added reinforcement is secured by the tightness of the dimpled film, so it can rest directly. The modified composite effect However, reinforcement and concrete without concrete cover must be taken into account.

According to information from soil experts, the non-"full-surface" introduction of the load forces (compressions) has no disadvantageous, but rather an improving effect on the compression modulus, as long as there are no "bad" base courses (cohesive soils, particle sizes <0.2 mm, capillary water-withdrawing layers).

In the case of nubbed foils placed on thermal insulation panels, any remaining air space under the nubs may additionally be regarded as being heat-insulating.

The requirements for the evenness of the substrate are not too great, since even larger unevenness can be compensated by the separating layer. The high demands on the flatness of the base layer or the base on which the conventionally used sliding film is intended to be effective in the conventional production of industrial floors are therefore completely eliminated. Only the static required plate thickness must be maintained as a minimum requirement.

When laying a planned underfloor heating, the heating coils can be placed in the correct position and, without any additional measures, between the knobs or depressions / elevations, if the knob module permits the inspection during concreting. (The partially interrupted by the heating coils transmission surface through fibers must be considered statically.)

Are day joints required - z. As in interruptions of the concreting process over several hours -, so they can be performed with a vertically inserted dimpled mat shear. The Zugverbund is usefully accomplished by an inserted under the shuttering, in the module of the nubs matching Baustahlgittermattenstreifen.

In the meantime, the Applicants have carried out numerous tests, including a composite concrete of concrete grade C 25/30 to EN standard as cover layer concrete to which additional steel fibers and plastic fibers (polypropylene fibers) were added. This concrete was applied to a plastic nap foil, in a first experiment over an area of 52 m ² , in a second experiment over an area also 52 m ² and in a third experiment over an area of 20 m ² , wherein in the first (second, third) trial, the concrete thickness varied from 5 cm (10 cm; 23 cm) over the protrusions of the dimpled sheet to 7 cm (12 cm; 25 cm) above the dimples of the dimpled sheet. Within the assessment period of one month, no cracks appeared in the cover layers.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Betonfläche, insbesondere eines Betonbodens, mit einer Trennschicht in Form einer Noppenmatte mit hohlen Noppen;

Fig. 2

eine schematische Darstellung einer erfindungsgemäßen Betonfläche, insbesondere eines Betonbodens, mit einer Trennschicht in Form einer Noppenmatte mit Vollnoppen.

Further advantages, properties, aspects and features of the concrete surface according to the invention, in particular of a concrete floor, will become apparent from the following description of a preferred embodiment of the present invention shown in the drawing. It shows:

Fig. 1

a schematic representation of a concrete surface according to the invention, in particular a concrete floor, with a release layer in the form of a dimpled mat with hollow nubs;

Fig. 2

a schematic representation of a concrete surface according to the invention, in particular a concrete floor, with a release layer in the form of a dimpled mat with full knobs.

1 and 2 schematically show a concrete surface 1 according to the invention, in particular a concrete floor, with a separating layer 3 arranged on a base 2 and a covering layer 4 of concrete arranged thereon, the separating layer 3 having a multiplicity of elevations 5 or depressions 6 so that the thickness of the cover layer 4 varies. As a separating layer 3, it is possible in particular to use a dimpled foil (eg made of plastic or metal), the elevations 5, z. B. in the form truncated pyramid or truncated cone humps, knobs or the like having. In this case, these elevations 5 may be formed hollow, ie between the elevations 5 and the substrate 2 is air (Fig. 1), or these elevations 5 consist of the interface material ("full nubs") (Fig. 2). The specially designed, provided according to the invention separation layer 3 prevents uncontrolled joint or crack formation during setting or

Drying of the concrete cover layer 4 and possibly leads to the formation of controlled, structurally harmless (micro) cracks.

The present invention according to a further, second aspect of the present invention is a method for producing the concrete surface according to the invention, in particular a concrete floor. A further subject of the present invention is therefore a method for producing a concrete surface, in particular a concrete floor, with a separating layer arranged on a substrate, onto which a covering layer of concrete is applied (eg cast), wherein a plurality of elevations acts as a separating layer or depressions having separating layer is used, so that the thickness of the cover layer varies. Similarly, the inventive method of avoidance or suppression or at least the control of joint and crack formation is used in concrete floors.

In other words, the method according to the invention is a method for producing a concrete surface, in particular a concrete floor, in particular as described above, the concrete surface is poured seamlessly from concrete and the concrete surface is poured with alternating areas of lesser and greater thickness, so that An uncontrolled joint or crack formation is avoided or controlled (micro) cracks are formed in the concrete or the areas of lesser thickness micro or Sollrißstellen the concrete form.

For example, the phrase "alternate areas of lesser and greater thickness" includes embodiments in which these areas vary in the manner of an egg carton, i. H. the areas of lesser thickness are not related, but are distributed so to speak grid-shaped over the concrete surface and in particular each local area of lesser thickness is completely surrounded by a region of greater thickness. If necessary, however, the concrete surface can also be designed to be complementary thereto.

For further embodiments and embodiments of the method according to the invention can be made to the above statements on the concrete surface according to the invention, in particular concrete floor, which apply mutatis mutandis with respect to the inventive method.

The subject matter of the present invention according to a further, third aspect of the present invention is the use of a separating layer, in particular foil, sheet metal or the like, for producing a concrete surface according to the invention, in particular a concrete floor, with a separating layer arranged on a substrate and a layer arranged thereon or applied thereto Cover layer of concrete, wherein as a release layer, a plurality of elevations and / or depressions having separating layer is used, so that the thickness of the cover layer varies.

For further embodiments and embodiments of the use according to the invention, reference may be made to the above statements on the concrete surface according to the invention, in particular concrete floor, which apply correspondingly with respect to the use according to the invention.

Claims (13)

1. Concrete surface (1), in particular concrete floor, with a separating layer (3) arranged on an underlying surface (2) and a concrete top layer (4) applied thereon, the separating layer (3) having a multiplicity of elevations (5) distributed regularly over the separating layer (3), so that the thickness of the top layer (4) varies and the top layer (4) has alternating regions of lesser and greater thickness with respect to the average thickness of the top layer (4), each local region of lesser thickness being completely surrounded by a region of greater thickness,
   characterized in
   that the regions of lesser thickness form predetermined cracking points, and the separating layer (3) is designed as a water-repelling or water-tight film.
2. Concrete surface according to Claim 1, characterized in that the separating layer (3) has a uniformly structured surface and/or in that the separating layer (3) has elevations (5) in the shape of truncated cones or truncated pyramids, in particular in the shape of studs, in a uniform distribution.
3. Concrete surface according to one of the preceding claims, characterized in that the average thickness of the top layer (4) varies because of the elevations (5) of the separating layer (3) by at least 5%, in particular by at least 10%, preferably by at least 15%, more preferably by at least 20%, particularly preferably by at least 25%, and very particularly preferably by at least 30%.
4. Concrete surface according to one of the preceding claims, characterized in that the top layer (4) and/or the entire concrete surface (1) is/are formed without any gaps.
5. Concrete surface according to one of the preceding claims, characterized in that the top layer (4) has micro-cracks of less than 0.2 mm in width.
6. Concrete surface according to one of Claims 1 to 5, characterized in that fibres, in particular synthetic fibres, such as polyolefin fibres, metal fibres, glass fibres or similar, are incorporated into the concrete of the top layer (4).
7. Concrete surface according to one of Claims 1 to 5, characterized in that the concrete of the top layer (4) does not contain any fibres.
8. Concrete surface according to one of the preceding claims, characterized in that the concrete surface (1) forms a large floor area for inside or outside use, in particular a hangar floor, a carriageway surface, a taxiing area for aeroplanes, or similar.
9. Concrete surface according to one of the preceding claims, characterized in that the concrete surface (1) can be subjected to a load, in particular can be travelled over.
10. Concrete surface according to one of the preceding claims, characterized in that the concrete surface (1) is cast, in particular is cast as a single piece.
11. Concrete surface according to one of the preceding claims, characterized in that the concrete surface (1) is designed monolithically and/or without any gaps.
12. Method of production of a concrete surface (1), in particular a concrete floor, in particular according to one of Claims 1 to 11, with a separating layer (3) arranged on an underlying surface (2) and onto which a concrete top layer (4) is applied, a separating layer (3) being used with a multiplicity of elevations (5) distributed regularly over the separating layer, so that the thickness of the top layer (4) varies and the top layer (4) has alternating regions of lesser and greater thickness with respect to the average thickness of the top layer (4), each local region of lesser thickness being completely surrounded by a region of greater thickness, so that the regions of lesser thickness form predetermined cracking points, and the separating layer (3) is designed as a water-repelling or water-tight film.
13. Method according to Claim 12, characterized by the features of the characterizing part of one of Claims 1 to 11.

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