EP1437451A1 - Wire-shaped element for reinforcing concrete - Google Patents

Abstract

The wire component has a strand with a central core (1) covered by an external layer. The external layer is formed by six notched steel wires (2) wound helically around the layer with a lay ranging between 125 and 400 millimeter. The strand is made in steel having half carbon assuring a resistance to rupture ranging between 800 and 1400 Newton per square millimeter with straightness lesser than about 25 mm for 1meter of length. Independent claims are also included for the following: (a) a reinforced concrete work comprising a metallic frame work achieved from reinforce wire component (b) a storage coil of the reinforce wire component in which the component is wound on a supporting chuck with a minimal winding diameter (c) a process of preparation of a reinforced wire component.

Description

The present invention relates to wire elements for reinforcing steel suitable for use as reinforcements, for example in the form of sheets metal, for the construction of roads, towpaths, etc ... and more generally of any reinforced concrete structure that can be built continuously or is likely to be.

Nowadays, the continuous construction of concrete road sections armed for example requires a long and tedious job of reinforcement when, as this is generally the case, the metal tablecloth is constructed from bars delivered in boots cut to a length of about a dozen meters and one must be dropped off following the other then tie them at the end two by two as the advancement of the structure by providing for an overlap length between bars consecutive not necessary to the robustness of the structure.

The present invention aims to reduce the assembly work of the reinforcement and avoid bad reinforcement links in the longitudinal direction.

To this end, the subject of the invention is a wire element for reinforcing reinforced concrete for the production of continuous structures, element characterized in that it consists of a strand comprising a central core surrounded by a series of '' at least six notched steel wires wound helically around it to form an outer layer, in that said winding helices have a pitch of between 125 and 400 mm approximately, and in that said strand is made of steel ensuring, on the one hand, a breaking strength of between 800 and 1,400 N / mm ² approximately and, on the other hand, a straightness such that its maximum deflection is less than approximately 25 mm for 1 m in length, a once the coiled strand is deployed.

By "notched wire" is meant a wire having on the surface a series of notches, or teeth, in relief. Thus, a notched wire within the meaning of the invention does not include surface wires indented, that is to say with hollow imprints.

The notched wire will preferably be substantially symmetrical. The notches will however advantageously oriented in a direction forming an angle substantially constant with respect to the central axis of the wire. This angle is for example between 2 and 60 °, advantageously between 5 and 45 ° and preferably around 30 °.

The body, or central core, is itself advantageously a steel wire, which wire can be smooth, notched or indented on the surface. It advantageously presents a cross section at least equal to 1.03 times the average cross section of the notched wires which surround it and which conventionally have a diameter between 3 and 6 mm.

The average section of a notched wire is determined by measuring the weight of a section of wire of determined length. For example for a length of 1 m of wire, the section is calculated by the following formula: Volume (mm3) / length (mm) = [1000 x Weight (g) / density (g / CM3)] / 1000

The helix pitch of the winding of the wires around the core is advantageously substantially constant and preferably between 200 and 300 mm.

The wired concrete reinforcing element according to the invention can be of monolayer type surrounding the central core or multi-layer type. For example, element may have a single layer of six wires wrapped helically around the core central. According to another example, the element comprises two superimposed layers surrounding the central body, the outer layer being formed of nine notched wires, while the inner layer is also formed by nine wires, this inner layer surrounding the central wire. Unlike those of the outer layer whose constituent wires are necessarily notched, the wires of the inner layer can be smooth, notched them also, or present intaglio prints.

According to a preferred variant, the element is made of a medium carbon steel grade, for example 0.46% C (in any case less than 0.6% and preferably between 0.3 and 0.6%) ensuring a breaking strength of between 1,000 and 1,300 N / mm ² approximately and a straightness such that its maximum residual deflection, coming from its plastic deformation on a winding support, is less than approximately 25 mm per meter of length (and preferably as low as possible) when it comes to be unwound from its support at the time of its deployment during the construction of the concrete structure for which it is intended, the roadway in particular. It will be noted that its diameter is of the order of 50 times and more less than that of the winding mandrel which receives it.

According to a particular embodiment, the notched wires of the layer external have at least two distinct series of notches: the notches of a first series being carried by a longitudinal zone of the surface of the wire distinct from the zone longitudinal of the surface which carries the notches of the second series. The notches have preferably a height between 0.25 and 0.60 mm, a width at the top between 1 and 1.5 mm, a length between 3 and 5 mm, and are arranged, for each series, one after the other with a spacing of between 3 and 6 mm.

The reinforcing wire element according to the invention advantageously has an overall cross section of between 90 and 200 mm ² .

Advantageously, the element has undergone a thermo-mechanical treatment at a temperature between 200 and 500 ° C, and preferably between 350 and 450 ° C, said treatment being carried out continuously on the element subjected to an elongation between 0.5 and 2%, preferably about 1%. Such thermo-mechanical treatment allows if necessary, relax certain mechanical constraints linked to the manufacturing process, but also to increase its elastic limit Re.

As will be understood, a major advantage of the invention is to be able present to the realization of a reinforced concrete structure in front of or which can be built in continuous, in particular at the parade on the site of use itself, a wire element of flexible steel reinforcement, with surface anchoring notches, and can be rolled out on site from its support reel as the work progresses, therefore in length infinite theoretical, in other words which, unlike rigid bars, does not require overlap length to be tied to ensure its continuity once deposited in the work in progress. Thus, the element advantageously has a length at least 100 meters, in particular at least 500 meters, preferably at least 1 000 meters.

Its flexibility, meanwhile, results from the very design of the wire element stranded around a core like traction cables, allowing in particular a curvature such as crowning on a storage and transport reel either feasible. However, it remains necessary that once deployed from its reel, as the progress of the structure, its residual curvature (its arrow) remains sufficiently low, at namely less than 25 mm, and preferably less than 20 mm, of deflection per meter of length, so that its immersion in the poured concrete before setting does not require anchoring on the ground otherwise than by its end at the start of the structure.

The invention also relates to the use of a wire element according to the invention to form a reinforcement in any concrete structure in front of or capable of being continuously produced on its site of use, and therefore such a reinforced concrete structure with a reinforcement at least partially formed with a wire element according to the invention.

The invention also relates to the packaging of the wire element according to the invention in the form of a coil, the diameter of the element to be wound being chosen to be less than 50 times and more the diameter of the support mandrel which receives it. The coil thus has an element length which can be adapted as required, for example example a length of 100 m, 500 m, 1,000 m, 2,000 m, 4,000 m, 5,000 m, 10,000 m, see more.

Finally, the invention also relates to a process for preparing a wired reinforcing element according to the invention, in which the successive portions of a element according to the invention are subjected to a thermo-mechanical treatment at a temperature between 200 and 500 ° C under an elongation between 0.5 and 2% for a period of 1 to 30 seconds, before being subjected to forced cooling to quickly lower its temperature below 150 ° C.

• la figure 1 est une vue longitudinale d'un élément suivant l'invention;
• la figure 2 est une vue en coupe (à plus grande échelle) de l'élément de la figure 1;
• la figure 3a est une vue à plus grande échelle d'un tronçon d'un fil cranté avant son placement en hélice autour du noyau central, tandis que la figure 3b est une coupe selon la ligne A-A du tronçon de la figure 3a;
• la figure 4 est une vue schématique d'une bobine suivant l'invention,
• et la figure 5 est une vue en coupe selon la ligne V-V de la bobine de la figure 4.

Special features and details of the invention will emerge more clearly from the following detailed description in which reference is made to the appended drawings, in which:

• Figure 1 is a longitudinal view of an element according to the invention;
• Figure 2 is a sectional view (on a larger scale) of the element of Figure 1;
• Figure 3a is an enlarged view of a section of a notched wire before its helical placement around the central core, while Figure 3b is a section along line AA of the section of Figure 3a;
• FIG. 4 is a schematic view of a coil according to the invention,
• and FIG. 5 is a sectional view along line VV of the coil of FIG. 4.

The reinforcing element (seven-wire) shown in Figures 1 and 2 includes a smooth steel wire 1 forming the central core of the element and a series of six steel wires notches 2 forming a compact outer layer covering the central core 1.

The notches are formed at the end of the drawing operation which makes it possible to obtain the desired diameter from a wire rod supplied with crowns. The drawn wire passes in a finishing cage with honeycombed rollers which print the notches on the surface of the wire. After stranding, a heat treatment is carried out (see below), the strand is then wound and directed towards the expedition park.

The average diameter of the steel wires 1 and 2 is for example around 4 to 5 mm. The average diameter of a notched wire is calculated on the basis of its weight per unit of length. The diameter of the wire 1 constituting the core is for example equal to approximately 1.03 to 1.05 times the average diameter of a notched wire.

The notched steel wires 2 are twisted around the central core 1 using a traditional stranding machine for cables to ultimately form a continuous twisted web enveloping the nucleus. During the stranding, each wire 2 thus follows a shaped path propeller whose pitch P is substantially constant and corresponds to approximately 23 cm.

The wires 2 have three rows of notches occupying three respectively separate longitudinal areas of the surface 20, 21, 22. Each row extends substantially parallel to the axis of the wire considered (see in Figure 3 wire 2 before its helical positioning). The rows of notches 20, 21, 22 extend over the surface of the wire in forming a constant angle with respect to the central axis 24 of the wire considered (this angle corresponds to the angle between the central axis and the plane of symmetry 25 of a notch).

The notches have for example a height "h" of about 0.4mm, a width of the base LB of about 1.6mm, a width at the top LS of about 1.2mm, and a spacing E between two successive notches of about 2.6mm (the notches are therefore arranged helically one after the other along the wire with a PP pitch of about 4.2 mm.

The rows of notches are for example arranged along longitudinal zones offset by 120 ° therebetween in order to be regularly distributed over the surface of the wire. Thus, the notches of a row are advantageously offset relative to the longitudinal position of the notches. other rows. The notches have for example a length "1" corresponding to approximately 100-120 ° of the circumference of the wire. The total cross section of the element is for example around 90 to 200 mm ² for a diameter of the element from 11 to 19 mm.

When helically laying the wires 2 around the core wire 1, the notches or teeth wires 2 are placed naturally so as to form stops which oppose longitudinal movements of the wires 2 relative to the core wire 1.

The wire element shown in Figures 1 and 2 is advantageously subjected to a heat treatment under traction. For example, processing is done in a way continues on successive portions of the element. This treatment is for example carried out at a temperature of approximately 400 ° C. while ensuring a tensile elongation of 1% of the portion during its heat treatment. The heat treatment is carried out during a ten seconds. After being treated, the portion is sprayed of water or passes into a water bath so as to lower suddenly (almost instantaneous) its temperature below 100 ° C. This treatment eliminates tensions present during the manufacture of the element, but also to increase its limit of elasticity Re for an elongation of less than 0.5%, for example for an elongation 0.2%.

Unlike prestressing concrete reinforcement steels, the steel of wires 1 and 2 according to the invention is preferably chosen in a "semi-hard" grade, with low or medium carbon (ie with a carbon content not exceeding 0.6% by weight) facilitating cold notching, and so that, on the one hand, the tensile strength Rm of the element is between 800 and 1400 N / mm ² and preferably between 1100 and 1200 N / mm ² , and that, on the other hand, after having been unwound from a coil 10 with a central mandrel 11 (see FIGS. 4 and 5) of diameter greater than 50 times the average diameter of the element, for example a diameter D of the mandrel equal to 75 cm, the maximum residual deflection coming from its deformation on the winding mandrel is less than 25 mm per meter of unrolled length.

Tests were carried out with strands according to the invention (breaking strength Rm of 1100 N / mm ² , cross section of approximately 95 mm ² notched peripheral wires around a smooth steel wire) and with conventional bars with a diameter of the order of 14 -16 mm.

In these tests, the strands or bars were placed in concrete elements with an anchoring depth of 28 cm. We thus determined the force necessary to first slide, the stress at the first slide, the maximum sliding force, maximum slip stress. In all cases, the break in adhesion or slippage occurred well before the mechanical failure of the strands.

The results of tests (carried out by the Free University of Brussels; Faculty of Applied Sciences, Civil Engineering) (sliding as a function of the applied force) are as follows (based on three measurements for the element according to the invention and based on two measurements for conventional bars): Type Force at first sliding (in KN - average value) First slip stress (in N / mm ² - average value) Maximum force (in KN - average value) Sliding stress at maximum force (in N / mm ² - average value) Invention: 15.7 mm diameter strand (cross section of (cross section of 140 mm ² ) 65 (between 60 and 68) 5.6 (between 5.1 and 5.8) 106 (between 104.5 and 107.7) 9 (between 8.9 and 9.1) Comparative: 1. Bar 14 mm in diameter (straight section 153 mm ² ) 67 5.8 101.2 8.7 2. 16 mm diameter bar (202 mm ² cross section) 80 5.3 121.4 8.6

It appears from this table that the following concrete reinforcement strand the invention, after having been unwound from a reel, makes it possible to obtain properties similar adhesion to that of conventional straight concrete bars. The record of the sliding force as a function of the sliding for the strands according to the invention demonstrates postcritical behavior, with progressive loss of grip, similar to that of concrete bars.

The element according to the invention is then advantageously used to produce continuous longitudinal reinforcement for concrete track sections, providing a significant reduction in the work of assembling the reinforcement and avoiding bad reinforcing links in the longitudinal direction.

It goes without saying that the invention cannot be limited to the exemplary embodiments given above, but that it extends to multiple variants and equivalents in the to the extent that its definition given in the following claims is observed.

For example, if the central core is preferably also made of steel, as the sons around him are not necessarily an obligation. Other materials may be appropriate. However, care will be taken to ensure that they can high temperatures of the strand heat treatment, if this is to take place.

In addition, the shape and orientation of the notches on the surface of the wires of the outer layer of the strand can be changed. In particular, on the same surface, a notch zone can have a different orientation than the other zones relative to the axis some thread.

Similarly, by "notching" or "notches", it should be understood that it is a question of relief patterns to ensure an anchoring effect of the concrete on the surface of the wire. These patterns in relief can be discontinuous patterns (teeth) distributed on the surface of the wire, as described in the examples above. They can also be continuous patterns, then forming rather ribs on the surface of the wire, it being understood however that in such a variant of realization, we lose a little specific surface for anchoring the concrete, all things equal moreover, compared to the tooth variant.

Claims (10)

Wired element for reinforcing reinforced concrete for the production of continuous structures, characterized in that it consists of a strand comprising a central core (1) covered by at least one external layer formed by at least six notched wires in steel (2) wound helically around it with a pitch of between 125 and 400 mm approximately, and in that said strand is made of steel ensuring a breaking strength of between 800 and 1400 N / mm ^{2 as} well as straightness such that its maximum deflection is less than about 25 mm for 1 m in length, once the coiled strand is deployed Wire element according to claim 1, characterized in that the pitch of the propellers is substantially constant and between 200 and 300 mm. Wire element according to Claim 1 or 2, characterized in that it is made of steel ensuring a breaking strength of between 1000 and 1300 N / mm ² as well as a straightness such that the maximum residual deflection is less than 25 mm per meter of unwound length of a support reel. Wire element according to one of Claims 1 to 3, characterized in that the notched wires (2) of the external layer have at least two series of notches (20, 21), the notches of a first series (20) being carried by a longitudinal area of the surface distinct from the longitudinal area of the surface which carries the notches of the second series (21), the notches having a height between 0.25 and 0.6 mm, a width at the top between 1 and 1.5 mm, a length between 3 and 5 mm, the notches being arranged one after the other with a spacing of between 3 and 6 mm. Wire element according to Claim 4, characterized in that the notched wires (2) have an average diameter of between 3 and 6 mm. Wire element according to any one of the preceding claims, characterized in that it has an average cross section of between 90 and 200 mm ² . Wire element according to any one of the preceding claims, characterized in that it has been subjected to a thermo-mechanical treatment at a temperature between 200 and 500 ° C, preferably between 350 and 450 ° C, said treatment being carried out continuously on the element subjected to an elongation of between 0.5 and 2%. Reinforced concrete structure comprising a metal reinforcement made from wired reinforcing elements according to any one of claims preceding. Storage coil for the reinforcing wire element according to any one of the claims 1 to 7, wherein said element is wound on a support mandrel with a minimum winding diameter of at least 50 times the diameter of said element. Process for the preparation of a reinforcing wire element according to claim 6, characterized in that , after drawing by drawing of a wire rod, the wires (1 and 2) which constitute it are subjected to a heat treatment. mechanical at a temperature between 200 and 500 ° C, and preferably between 350 and 450 ° C, said treatment being carried out continuously on said wires subjected to an elongation of between 0.5 and 2%, preferably about 1 %.

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