EP0080454B1 - Reinforcing mat for armoured concrete - Google Patents

Description

The invention relates to a reinforcement mat for reinforced concrete, consisting of intersecting longitudinal and transverse wires welded to one another at the point of intersection with an improved bond by embossing, ribbing or in some other way.

In a reinforcement mat of this type known from DE-B No. 2315520, all the longitudinal elements have the same mutual axial spacings and at least some of the longitudinal elements are in the form of wire pairs with welded-on stiffening webs; the transverse wire end pieces can be bent back in the form of loops to the longitudinal edge elements for the purpose of stiffening the mat, the loops also being intended to enable the formation of force-fitting mat joints. The purpose of this known mat design is either to increase the stiffness of the mat with a given steel effort for the cross wires or to decrease the steel effort for the cross wires with a given stiffness.

In a further reinforcement mat of the type specified in the introduction, in which the longitudinal elements likewise have the same mutual axial spacings, two parallel, adjacent transverse wires are assigned to one another and their end parts projecting beyond the longitudinal edge elements are connected in such a way Loops bent back so that the two transverse wires together with the loops form an essentially closed wire pull welded to the longitudinal elements, with two parallel long sides and semicircularly narrow sides.

With these known mats, a load-bearing mat joint is to be formed in such a way that two mats are pushed together until their longitudinal edge elements come to lie next to one another and only the loops of each mat overlap the neighboring mat. The fact that the longitudinal edge elements of the mats are formed as single wires and the other longitudinal elements as double wires prevents a line wire accumulation in the mat joint. In this way, i.e. H. Just using the loops to be able to transmit a sufficient cross-bar force for a load-bearing mat joint requires a large loop length despite the use of cross wires with improved connection properties, which on the one hand involves a lot of effort and cross-wire material and on the other hand has the consequence that while maintaining the mat width from standard programs, lattice webs with the large cross-wire protrusions required for loop formation can no longer be produced on lattice welding machines in use for the standard programs.

A load-bearing mat joint can also be achieved in a known manner by covering the mat edges by three stitches or four welding points. Here, however, there is the disadvantage that twice as much wire material lies in the area of coverage as would be necessary to absorb the forces per se. It was also found that when several welding points are included in the power transmission path of a cross wire, the individual welding points of the cross wire in question are mostly involved in the power transmission in very different ways, so that no optimal power transmission conditions have yet been achieved either.

In this context, reference is made to AT-B No. 269434, which deals with the task of bringing about simplifications and reductions compared to the previously common storage and list mats with a new reinforcement program. For this purpose, in the case of mats suitable for the formation of load-bearing impacts, four narrowed (and possibly thinner) longitudinal wires should be consistently the same width on each mat edge, at mutual distances that are the same for all mats, and inside the mat also in the same, but graded from mat to mat Clearances (possibly thicker) longitudinal wires must be arranged. By covering the edges by three meshes of the same width for all mats, such mats enable the formation of load-bearing joints, whereby in the sense of saving steel, the cross-wire protrusions should only be made so large that perfect welding at the wire crossing points is possible.

If one compares the mats mentioned in the introduction, which have force-transmitting loops, with the last-mentioned mats with predetermined covering edges, each containing four longitudinal wires, then contradicting teachings can be seen with regard to the formation of the mats. Instead of allowing the cross wires to protrude far beyond the longitudinal edge elements, forming the protruding ends into loops capable of transmitting force and at the same time providing a single wire on each mat edge and double wires inside the mat as longitudinal elements in order to avoid line wire accumulations in the joint area, the cross wires are made as possible in the second case only extended so far beyond the longitudinal edge wires that a flawless welding at the wire crossing points is just still possible, while on the other hand a steel accumulation of four longitudinal wires each from two adjacent mats in the area of their overlap is accepted on each edge of the mat.

The person skilled in the art, who is familiar with the two types of mats, will therefore not be encouraged to combine partial features of the concepts because of the completeness and contradiction of their concepts; rather, he will be given the choice of either sacrificing cross-wire material for the necessary force transmission in the cross-direction of the mat and instead sacrificing longitudinal wire material to save or vice versa.

The invention is based on the object in the context of a new mat and laying pro grammes to form a reinforcement mesh of the type specified in the introduction in such a way that an optimal force transmission between the cross wires of adjacent meshes is ensured and reinforcement composed of meshes according to the invention can be adapted practically without material losses within wide limits to different structural dimensions in the cross-wire direction of the meshes. In addition, mats according to the invention should be able to be produced while maintaining the width of standard mats on the mesh welding machines used for them.

The invention is initially based on the long-known fact that a local increase in the load-bearing capacity of a tensile structure is effective not only in the immediate area in which it is caused, but also affects both sides of this area up to a certain distance (so-called load-bearing plate areas). If, in some areas, more steel cross-sectional area per unit of width is concentrated in a tensile structure than in the other areas of the structure, the areas of greater reinforcement intensity take on part of the load of the areas of lower reinforcement intensity. In practical terms, this means that the reinforcement can be invoiced with a value that corresponds to the average of the reinforcement intensity of the heavily reinforced areas and the reinforcement intensity of the weakly reinforced areas.

From this, as already mentioned, knowledge, which is in itself old, has so far not been of any practical use because the intended covering mass must of course be specified on the laying plans and strictly adhered to on the construction site, which requires very careful and therefore time-consuming and uneconomical laying of the mats . Furthermore, it was very difficult to determine the start and end of a mesh in the installed bond in the reinforcement mesh that had been customary up to now, especially in the case of two-axis reinforced tensile structures, so that subsequent checking of the laying method by the declining engineer was almost impossible. Therefore, there were concerns about the cost-effectiveness of the precise laying required as well as concerns about the safety of the building due to uncontrollable misplacement, which made it advisable not to use the knowledge presented above.

Furthermore, the invention is based on the second finding that when several welding points are included in the force transmission path of a cross wire, the individual welding points of the relevant cross wire are involved in the force transmission to a greater extent, the greater the mutual distance between the longitudinal wires. This applies in particular to ribbed wires or wires which are otherwise provided with improved composite properties, because these transmit the forces prevailing in them to the concrete in a relatively short way, which relieves the second of two successive welding points.

Only when the two longitudinal edge wires and the two outermost weld points have a transverse wire on each edge of the mat small mutual distance, an approximately uniform load distribution can be achieved in the two welding points, so that even when formation of support bumps in general, already two welding points in the Überdek _- kung area the sufficiency can be found.

The object of the present invention is now achieved on the basis of the findings described by the combination of the features that the transverse wires protrude beyond the longitudinal longitudinal wires with transverse wire parts that are bent back in the mat plane in the direction of the longitudinal longitudinal wires, and that the longitudinal wires are symmetrical to the longitudinal central axis of the mat are arranged partly in larger and partly in smaller mutual distances, at least the major part of the longitudinal wires lying in the interior of the mat being at a greater mutual distance than the longitudinal edge wires, and two longitudinal wires arranged at a small mutual distance being provided on each mat edge.

Due to the bending back of the transverse wire end parts, which improves the transmission of force in the transverse direction, and the simultaneous narrowing of two longitudinal wires on each mat edge, which ensures that the second longitudinal wire is carried along, the anchoring of the transverse wires in the concrete is improved in such a way that the formation of load-bearing impacts by overlapping the loops and the length of the loops and thus the cross-wire protrusions can be dimensioned so short that the length of the two longitudinal longitudinal wires of adjacent mats can be such that mesh mats according to the invention can also be produced in standard widths using conventional mesh welding machines. In addition, there is the advantage that the transfer of lateral force is not significantly impaired if one of the two welding points on the edge of the mat fails due to a manufacturing defect or subsequent damage to a mat.

In addition, this edge formation of the mat according to the invention minimizes the cross-wire sections lying next to one another in the overlapping area of adjacent mats and thus the losses of cross-wire material.

The arrangement of longitudinal wires in the interior of the mat symmetrically to the longitudinal center axis of the mat, partly in larger and partly in smaller mutual distances, also creates markings for the overlapping laying of adjacent mats. As a result, the mats can be laid on the construction site quickly and thus efficiently without special aids in such a way that they can be easily adapted to the predetermined structure dimensions in the direction of the mat transverse wires. The chosen form of installation always remains light even afterwards controllable because the transverse wire end parts bent back in the direction of the edge longitudinal wires form clearly recognizable irregularities in the finished mat arrangement, so that the distance along which the edges of adjacent mats overlap always remains easily measurable.

In order to shorten the required elongated length of the transverse wire end pieces bent back into loops and thus to save material, the transverse wire end pieces on each mat edge can be bent back at least up to the outermost edge longitudinal wire and welded to it.

In the case of high-rib steels and steels with a strongly embossed surface, the anchoring effect of the wire surface is so good that it is not statically necessary to weld transverse wire ends bent back up to the edge longitudinal wires with the edge longitudinal wires. In these cases, even L-shaped hooks are sufficient, which are bent only parallel to the longitudinal wires.

However, the cross-wire protrusions are preferably bent back by a full 180 °, because the loops thus obtained can be seen much more clearly in the laid mat arrangement due to their circular-arc-shaped section than hooks, the two legs of which run essentially parallel to the wires of the two wire shares. In addition, each transverse wire end part bent back to a longitudinal edge wire is advantageously connected to the longitudinal edge wire by at least one tack weld, in order to ensure that the loop is not bent open during handling of the mat during transport and on the construction site, thereby at least functioning as a clear marking for the overlap widths neighboring mats would lose.

In order to make the different mutual distances of the longitudinal wires clearly distinguishable from one another, according to a further feature of the invention, the small distances of the edge longitudinal wires should be equal to or less than half of the larger longitudinal wire distances. Preferably, one will choose the small distance of about 50 mm, because in this case with the presently stationary in use ^{Gitterschweissma:} machines a welding of the transverse wire to the two arranged in this spacing longitudinal wires is still possible by two separate electrodes. If one went down to a smaller welding point distance, then both welding points would have to be fed by a common electrode. This would mean that the welds of the transverse wire with two longitudinal wires arranged at a small mutual distance would be weaker with the same electrode feed throughout than the welds of the same transverse wire with longitudinal wires arranged at a large mutual distance, which would obviously run counter to the purpose of the invention.

The invention allows, as will be described in more detail later, mat designs which, in the case of overlapping mat laying, open up the possibility of calculating the steel accumulations in the overlapping areas as being evenly distributed, as well as mat designs which, given a given mat width, allow for a mat production by appropriate choice of the longitudinal wire spacing Easily adjustable and convertible multi-point lattice welding machines with a predetermined, uniform arrangement of the electrodes enable, and finally mat designs, which result in a largely uniform, related steel cross-section due to an edge-saving effect even with overlapping mats of large width and small overlap.

• Fig. 1 bis 4 verschiebene Matten nach der Erindung in Draufsicht; die
• Fig. 5 bis 10 in Draufsicht unterschiedliche Verlegearten von Matten nach Fig. 4; die
• Fig. 11 und 12 zwei weitere erfindungsgemässe Matten in Draufsicht, und die
• Fig. 13 und 14 schliesslich noch zwei erfindungsgemässe Matten im Querschnitt.

The invention is explained in more detail below with reference to the drawings using exemplary embodiments of mats according to the invention. It shows: the

• 1 to 4 shifting mats after the invention in plan view; the
• Fig. 5 to 10 in plan view different types of laying mats according to Fig. 4; the
• 11 and 12 two further mats according to the invention in plan view, and
• 13 and 14 finally two cross-sectional mats according to the invention.

1 shows longitudinal wires 5 with the inner area of the mat and longitudinal wires 3, 4 in the two edge areas. The longitudinal wires in the interior are arranged at the same mutual distance a. For the sake of simplification, the mat is not completely drawn, rather n-1 longitudinal wires are omitted in the inner area, which was indicated by the distance _" n - a" in the area of the symmetry axis of the mat.

The two longitudinal edge wires 3, 4 are arranged at a mutual spacing b which is substantially smaller than the mutual spacing a of the other longitudinal wires and is preferably approximately between 20 and 50 mm.

The transverse wires 1 are also arranged at the same mutual distance c, which, however, is generally greater than the distance a between the inner longitudinal wires. The end parts 2 of the cross wires 1 are bent back at each mat edge symmetrically to the mat longitudinal axis X-X to form loops and are welded to the outermost edge longitudinal wire 3 at 11. The loops can, however, also extend as far as the second longitudinal longitudinal wire 4 and can only be welded to this or to both longitudinal longitudinal wires 3, 4.

If the clearance c between adjacent transverse wires 1 in the case of mats according to FIG. 1 is greater than twice the amount of the external dimension s measured in the direction of the longitudinal wires 5 of the loops 2 formed by the bent-back transverse wire end pieces, the mats can be turned alternately by 180 ° be stacked to save space, because then, as indicated in FIG. 1 with dashed lines, each cross wire 1 'of the turned mat in one plane next to a cross wire 1 of the non-turned Mat comes to rest and the loops 2 'of the cross wire 1' of the turned mat find space between a cross wire 1 and the loops 2 of the adjacent cross wire 1 of the non-turned mat.

According to the embodiment according to FIG. 2, the end parts 2 of the cross wires 1 can also be bent back in the form of round hooks (left mat edge) or L-hooks (right mat edge) in the direction of the longitudinal edge wires 3 and not welded to them.

A special form of a mat according to the invention is shown in FIG. 4. This mat, in which the transverse wire end parts 2 are led back, for example, to the longitudinal edge wires 3 and can be connected to them by a tack weld at 11, also has two arranged on both sides of the longitudinal central axis XX , a separation point creating longitudinal wires 7, 8 still two groups of two longitudinal wires 12, 13 and 14, 15 arranged at a small distance. The longitudinal wires 12, 13 lie approximately in a quarter of the mat width, the longitudinal wires 14, 15 approximately in a third of the mat width.

As can now be seen from FIGS. 5 to 10, mats of this type can be adapted by suitable selection of the laying form in small increments within very wide limits to different structural dimensions.

5 to 10, the reference numerals of all parts of a mat are provided with the letter a, those of all parts of the other mat with the letter b.

5, the two mats are laid in such a way that the longitudinal wires 4a, 4b of the edge shares of longitudinal wires 3a, 4a and 3b, 4b, which are arranged at a small mutual spacing, touch one another. With this type of installation, the mats cover the largest possible board width. The mutually facing edges of both mats remain clearly recognizable by the loop wire end portions 2a, 2b which are bent over in a loop.

6, the longitudinal wires 4a, 4b lie next to longitudinal wires 13b, 13a. The two mats now cover one another by about a quarter of their width, so that the area reinforced by the mats has become narrower than in the case of FIG. 5. At the same time, however, a larger steel cross-sectional area compared to the case according to FIG. 5 can be taken into account, so that practically no material losses occur.

A further form of laying is shown in FIG. 7, according to which the longitudinal wires 4a, 4b now come to lie next to the longitudinal wires 15b, 15a. With this type of installation, the mats overlap each other by ¹ f _{3 of} their width and therefore cover an even narrower section of the structure. The loop-shaped transverse wire end parts 2a, 2b can also be clearly seen here, with the aid of which the boundaries of the individual mats remain recognizable even in the installed mat assembly.

8 to 10, the laying forms of FIGS. 5 to 7 are repeated, but the left mat is severed along its axis of symmetry X-X. According to FIG. 10, the mats laid in the manner shown there thus cover a structure width that is only slightly larger than that which can be covered by a single mat.

The mat shown in FIG. 11 is largely similar to that shown in FIG. 3. Since it is not possible to build up any mat widths with as small and large mutual wire spacing as possible in such a way that the large wire spacings are always the same, integer multiples of the small wire spacings, but the standard mat widths used in the individual countries are selected on the basis of very different aspects. it may be expedient to separate the two coulters 3, 4 and 9, 10 arranged on each mat edge by longitudinal wires arranged at a small mutual distance b, as shown in FIG. 11, by a distance e which is greater than the mutual Distance a of the longitudinal wires 5 in the interior of the mat.

Assuming, for example, that the standard mat width is 2400 mm (as is currently the case in Austria), the loop-shaped transverse wire end pieces 2 protrude on both sides by 50 mm over the longitudinal edge wire 3, the small mutual distances b between the longitudinal wires 3 and 4 or 9 and 10 are also 50 mm and the mutual distances a between the inner longitudinal wires 5 are each 150 mm, then a mat with distances 6 x 50 = 300 mm and 14 x 150 = 2100 mm, that is to say 2400 mm in width, can be built up. In this mat, the longitudinal wires 4 and 10 are then at a mutual distance of 150 mm and the mat corresponds to that shown in FIG. 3.

However, if the mats are to be 2050 mm wide, as is customary, for example, in Switzerland, then it is no longer possible to build up the mats with small distances b of consistently 50 mm and large distances a of consistently 150 mm. In this case, a distance b of 50 mm can be provided between the longitudinal wires 3, 4 and 9, 10 and an edge projection of 50 mm can also be provided for the loops. The distance e between the longitudinal wires 4 and 10 can be 200 mm and finally eight longitudinal wires 5 can be arranged in the interior of the mat at a distance of 150 mm each. Together then results
6 x 50 + 2 x 200 + 9 x 150 = 2050 mm total width.

In general, the wish to produce all mats with the permitted maximum width for reasons of economy of the mat transport can be taken into account in that the longitudinal wires 5 in the interior of the mats according to FIG. 12 (apart from those possibly according to FIG. 4 to facilitate division of the mats) Mat provided longitudinal wires 7, 8 in the middle of the mats) at the same mutual distance a and two longitudinal wires 4, 5a are arranged at a mutual distance e near each mat edge, which is greater than the mutual distance b of the longitudinal longitudinal wires 3, 4 and deviates from the mutual distance a of the longitudinal wires 5 in the interior of the mat.

In mats according to FIG. 3, in which two groups 3, 4 and 9, 10 of longitudinal wires arranged at a small mutual distance b are provided on each edge of the mat, this teaching, as can also be seen from the cross section according to FIG. 13, is fulfilled because the adjacent longitudinal wires 4 and 10 of these two wire shares have the distance e from one another, which is greater than the mutual distance b of the longitudinal edge wires and also greater than the distance a of the longitudinal wires in the interior of the mat.

A similar mat results according to FIG. 14 if the distances e ₁ between the adjacent longitudinal wires 4 and 10 of the two longitudinal wire groups 3, 4 and 9, 10 and the distance e2 between the inner longitudinal wire 9 of the inner longitudinal wire family 9, 10 and him adjacent longitudinal wire 5 of the mat interior are different from each other.

This measure and a further embodiment of the invention, explained with reference to FIGS. 13 and 14, can also achieve a better uniformity of the steel cross-section in the association of overlapping laid mats.

In the case of overlapping laying of wide mats, the local steel accumulations caused by the edge overlaps may usually only be billed as evenly distributed according to national regulations if the edge areas of adjacent mats overlap so far that the distance between the left boundary of the overlap area and the right edge a mat from the right boundary of the overlap area on the left edge of the same mat is equal to or less than a prescribed limit. In all those cases in which the edges of adjacent mats overlap less, the excess steel would be lost in the overlap area.

This can be prevented within the scope of the invention in that at least the diameter of the wires of the longitudinal edge wire sheet 3, 4 _- but advantageously also according to FIGS. 13 and 14 also the diameter of the wires of a second sheet 9, 10 of longitudinal wires arranged at a small mutual distance b 9, 10, which are adjacent to the wire sheet 3, 4, is chosen to be smaller than the diameter of the longitudinal wires 5 in the inner region of the mat. This measure reduces the steel cross-sectional area at the edge of the single mat.

For the same purpose, either alone or together with the reduction of the wire cross-sections at the edge of the mat, in the manner already explained, the distance e of the wire 4 from the wire 10 and possibly also the distance of the wire 9 from the wire 5 adjacent to it Mat area are enlarged. For most mats, at least for those where the diameter of the individual wires is larger than the minimum diameter, which must be adhered to in any case for reasons of rust resistance, these measures can reduce the steel cross-sectional area at the edge of a mat to such an extent that If two adjacent mats overlap in such a way that only the wires 3, 4 of their edge wire coulters overlap, there is an at least approximately uniform distribution of the steel cross-section over the entire reinforced area, which is equal to the steel cross-section in the interior of the mat. In this case of overlap, therefore, no steel is lost even if the overlapping areas of the mats are too far apart from one another to allow any steel accumulation to be included, because the wires lying in the overlap area complement one another with the same related steel cross-section that is present inside the mat.

If the mats continue to overlap by several stitches, as long as the distance of the overlap zones from one another is greater than the limit provided for the calculation, steel losses occur, but these always remain smaller than if all the wires had the same diameter and the same mutual distance.

Claims (14)

1. A reinforcement mat for reinforced concrete, consisting of longitudinal and transverse wires having their bonding improved by ribbing _'or stamping or in some other way, which wires cross one another and are welded together at the crossing-points, characterized by the combination of features that the transverse wires (1) project beyond the edge longitudinal wires (3, 4) with transverse wire end portions (2) which are bent back in the plane of the mat in the direction towards the edge longitudinal wires (3, 4), and that the longitudinal wires (3-10; 12-15) are arranged symmetrically about the longitudinal centreline (X-X) of the mat partly at wider and partly at narrower pitch, at least the preponderant part (5) of said longitudinal wires (5; 5,7,8; 5,9,10) lying in an inner region of the mat having a wider pitch than the edge longitudinal wires (3, 4), and two longitudinal wires (3, 4) being arranged at each edge of the mat at narrow pitch.

2. A reinforcement mat as in Claim 1, characterized in that the projecting end portions (2) of the transverse wires are bent back at each edge of the mat in the shape of a loop extending at least as far back as the outermost of the family of longitudinal wires arranged at narrower pitch, and are welded to at least one of said longitudinal edge wires (Fig.1).

3. A reinforcement mat as in Claim 1 or 2, characterized in that said narrower pitch (b) of the edge longitudinal wires (3, 4) is at the most equal to half said wider pitch (a) (Fig. 1 and 2).

4. A reinforcement mat as in one of the Claims 1 to 3, characterized in that the pitch (c) of adjacent transverse wires (1 ) of the mat is greater than twice the outside dimension (s), measured in the direction of the longitudinal wires (3, 4), of the loops formed by the bent back end portions (2) of the transverse wires (Fig. 1).

5. A reinforcement mat as in one of the Claims 1 to 4, characterized in that the two longitudinal wires (7, 8) adjacent to the longitudinal centreline (X-X) of the mat are arranged at the narrower pitch (Fig. 4).

6. A reinforcement mat as in one of the Claims 1 to 5, characterized in that the longitudinal wires (5) in the inner region of the mat, optionally with the exception of the two innermost longitudinal wires (7, 8), are arranged at equal pitch (a), and that near each edge of the mat two of the longitudinal wires (4, 10; 4, 5a) have a pitch (e) which is wider than the pitch (b) of the edge longitudinal wires (3,4) and differs from the pitch (a) of the longitudinal wires (5) in the inner region of the mat (Fig. 11 and 12).

7. A reinforcement mat as in one of the Claims 1 to 6, characterized in that adjacent to the family of longitudinal wires (3, 4) arranged at narrower pitch and provided at each edge of the mat, there is at least one further family of longitudinal wires (9, 10) arranged at narrower pitch, the inner longitudinal wire (4) of the family of longitudinal wires (3,4) arranged at the edge of the mat and the outer longitudinal wire (10) of said further family of longitudinal wires (9, 10) being at a greater distance apart (Fig. 3, 11, 13 and 14).

8. A reinforcement mat as in Claim 7, characterized in that the longitudinal wires (4, 10) which are adjacent to one another in said two families of longitudinal wires (3, 4 and 9, 10) arranged at narrower pitch. (b) and provided at each edge of the mat have from one another a distance (e₁ ), and the inner longitudinal wire (9) of said inner family of longitudinal wires (9, 10) has from the longitudinal wire (5) adjacent to it in said inner region of the mat distance (e₂), which distances (e₁ and e_z respectively) are in each case greater that the pitch (b) of the edge longitudinal wires and differ from the pitch (a) of the longitudinal wires (5) in the inner region of the mat (Fig. 14).

9. A reinforcement mat as in Claim 8, characterized in that the distance (e₁ ) between the adjacent longitudinal wires (4,10) of said two families of longitudinal wires (3,4; 9, 10), and the distance (e₂) between the inner longitudinal wire (9) of the inner family of longitudinal wires (9, 10) and the longitudinal wire (5) adjacent to it in the inner region of the mat, are different from one another (Fig. 14).

10. A reinforcement mat as in one of the Claims 1 to 9, characterized in that families, preferably pairs, of longitudinal wires (3, 4; 12, 13; 14, 15) arranged at narrower pitch are provided at the edges of the mat and at least approximately in the region of one quarter to one third of the way across the width of said mat (Fig. 6).

11. A reinforcement mat as in Claim 8, characterized in that the distance (e) between the two longitudinal wires (4, 10) which are facing each other in said two families of longitudinal wires (3, 4; 9,10) arranged adjacent to each edge of the mat is greater than the pitch (a) of the preponderant number of longitudinal wires (5) in the inner region of the mat (Fig. 13).

12. A reinforcement mat as in one of the Claims 1 to 11, characterized in that the end portions (2) of the transverse wires, projecting beyond the outermost longitudinal wires, are in the plane of the mat bent in the shape of a hook or of an angle, respectively (Fig. 2).

13. A reinforcement mat as in one of the Claims 7 to 12, characterized in that the edge longitudinal wires (3, 4) have a smaller diameter than the remaining ones of the longitudinal wires (5) (Fig. 1 to 3).

14. A reinforcement mat as in one of the Claims 7 to 13, characterized in that both the edge longitudinal wires (3,4) and also the adjacent pair of longitudinal wires (9, 10) have a smaller diameter than the remaining ones of the longitudinal wires (5) (Fig. 3,11, 13 and 14).

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