WO2001088301A1

WO2001088301A1 - Steel fibers

Info

Publication number: WO2001088301A1
Application number: PCT/EP2001/005456
Authority: WO
Inventors: René Pepin
Original assignee: Trefilarbed Bissen S.A.
Priority date: 2000-05-17
Filing date: 2001-05-14
Publication date: 2001-11-22
Also published as: EP1282751B1; EP1282751A1; PT1282751E; ATE340903T1; ES2272492T3; DK1282751T3; DE50111098D1; AU2001269008A1; LU90584B1

Abstract

The invention relates to steel fibers to be used to reinforce formable materials, especially concrete, comprising a central part, two intermediate parts offset and joined to said central part as well as an end part joined to each intermediate part. Said end part is offset from the intermediate part, such that said end part, substantially parallel to said intermediate part, is characterized in that it is partially flattened.

Description

wire fiber

introduction

The invention relates to a rod-shaped wire fiber made of metal for use in the reinforcement of moldable materials, in particular concrete.

For concrete, which in the following also means screed and mortar, steel fibers are used as reinforcement elements. A reinforced with steel fibers concrete is in its properties, such as tensile strength, breaking strength, shear strength, Streckvermögeή, ^' "strength, dynamic strength, fatigue resistance, improves therefore It is used to an ever greater extent, the steel fiber is intended to have the following characteristics:.. You should tough and firm. It should not break when mixed with concrete or aggregates. It should not be too short or too thick, otherwise it will be insufficient in strengthening. It should not be too long or too thin, otherwise it is difficult to process and tends to form spherical lumps of cement - also called hedgehogs - Generally a steel fiber cross section of 0.1 to 1.4 mm2, a steel fiber length of 10 to 70 mm and a weight fraction of the steel fibers of 15 to 150 kg / m3 of concrete recommended In addition to their properties, the cost-effective production of steel fibers is a top priority.

Steel wire fibers for reinforcing concrete have been known for a long time, namely in different configurations in the form of a rod, evenly corrugated over the length, chip form or also with surface profiling, as for example in the magazine "Beton, 1989, Issue 4, pages 178 to 180 "by Gerd Humert" Steel wire fibers in practice ".

In order to increase the tensile strength and strength of the concrete, adequate adhesion and anchoring of the wire fibers in the concrete is required in particular. A number of proposals have been made to this end. According to EP-PS 0130 191, wire fibers are corrugated uniformly over their length, as is one in the Dutch patent application 8001609 Proposed evenly alternating stepwise (right-angled corrugated) wire fiber over its length.

Wire fibers are known from US Pat. No. 6,045,910 which have a center piece with a Z-shaped or L-shaped hook and each consist of an intermediate piece and an end piece. The Z- or L-shaped hooks i.e. the intermediate pieces and the end pieces are deformed by flattening.

DE-OS 23 05 651 also proposes wire fibers which either have a uniformly profiled surface in the longitudinal direction or are entirely deformed from the rod shape into other configurations, such as S-shape, O-shape, triangular shape, loops and the like, to improve anchorage in concrete. Also known from the British patent specification 1446 855 are corrugated wire fibers with widened ends, as well as from US Pat. No. 2,677,955 with corrugations and reinforcing fibers designed for the whole of the rod shape shaping reinforcing fibers for concrete. To further improve the adhesion of the wire fibers made of metal in concrete, a reinforcing fiber in the form of a rod made of metal was proposed according to DE-GM 88 15 120, the surface of which is profiled by means of grooves. Furthermore, a further increase in the adhesiveness of wire fibers made of metal in concrete, which are provided with surface profiles, was achieved in that wire fibers present in rod form are bent at their ends, as described, for example, in DE-GM 90 06 524.

An unsolved problem, particularly in the area of shotcrete, is that a large part of the steel fibers rebound. In the literature ("Steelfibre Rebound in Shotconcrete" Hugo Armelin & Nemkumar Banthia, Canadian Society of Civil Engineering, October 1998) one speaks of 30-80% of the fibers that bounce back, but only between 20 and 40% of the concrete bounce back. In others Words, more fibers rebound than concrete, making the content of fibers in the finished concrete difficult to predict. Object of the invention

It is therefore an object of the present invention to provide wire fibers made of metal for use in the reinforcement of moldable materials, in particular concrete, which have a lower rebound rate than conventional fibers.

General description of the invention

This object is achieved by forming wire fibers made of metal according to claim 1.

With the invention, a wire fiber is created which has a lower rebound rate and at the same time allows good anchoring of the fiber. The wire fiber according to the invention is thus able to allow good anchoring and adhesion in concrete, in which work is also carried out with different grain sizes and finenesses of the additives, by means of a differentiated shape. In addition, the wire fiber according to the invention is easy to pour and can be distributed evenly within the still flowable concrete mass. Advantageous embodiments of the invention can be found in the characterizing features of the subclaims.

The metal wire fiber has a middle piece, two bent intermediate pieces connected to the middle piece and in each case one end piece connected to the intermediate pieces. The end piece is bent relative to the intermediate piece in such a way that the end piece is essentially parallel to the middle piece. The end pieces are flattened at least in a partial area

The middle piece and the two bent intermediate pieces have a substantially circular cross section. Wire fibers are produced in very large numbers, so that the manufacturing tolerances are relatively large. The wire fibers are preferably of symmetrical design, the middle piece having an intermediate piece with the corresponding end piece on each of the two sides.

According to a preferred embodiment, the two end pieces and the middle piece of the wire fiber lie in one plan.

Usually the two intermediate pieces of the wire fiber are in one direction i.e. bent to one side.

Wire fibers for use in the reinforcement of formable materials, in particular concrete, usually have a length of approximately 10 to 70 mm and a maximum durometer of up to approximately 1.3 mm. When we speak of a wire fiber with a maximum diameter of up to approximately 1.3 mm, not only circular cross sections of the wire fiber are addressed here, but also oval or rectangular cross sections or approximately rectangular or similar cross sections, the maximum diameter then being based on the equivalent Diameter refers.

As a rule, the intermediate piece together with the end piece has a length of 5 to 20 times the diameter of the wire fiber, the flattened end piece has a length (I, I ') of 2 to 10 times, preferably 3 to 5 times, the diameter of the wire fiber and a width (B) of 1.5 to 3.5 times the diameter of the wire fiber, the kinked intermediate piece has a "height" (h, h ') of 2 to 10 times, preferably 3 to 5 times, the diameter of the wire fiber.

For special applications, these dimensions can of course also be exceeded or undershot.

The wire fibers according to the invention can be produced without problems using the conventional machines, the shaping parts, ie the rollers of these machines, of course having to be changed in accordance with the shape of the wire fibers Description based on the figures

An embodiment of the invention is described below with reference to the accompanying figures. Show it:

Fig.1: a wire fiber in the side view, Fig.2: a wire fiber in the top view, in Fig. 1 is a wire fiber made of a steel with high tensile strength, which in natural size has a length (L) of 30 mm with a diameter of 0.7 mm. Wire fibers, preferably in lengths of 30 to 60 mm with diameters of max. 1, 3 mm are used for the reinforcement of concrete, in which they are mixed in evenly while the concrete is still flowing.

1 has a center piece L 'and at the two ends of this center piece a z-shaped double bend or hook. In principle, these hooks are symmetrical and have an intermediate piece with an angle α relative to the middle piece of approximately 45 ° +/- 10 ° and an end piece which is essentially parallel to the middle piece and by h, h '= 1, 8 +/- 1 mm offset. The end pieces are partially or completely flattened, which improves the anchoring and reduces the rebound of the wire fiber.

The middle piece and the intermediate pieces have a substantially circular cross section.

The flattened end pieces in this example are approximately 2-4 mm long (I, I ') and 1.2 to 2 mm (B) wide and are dovetail-shaped.

The wire used to make this wire fiber has a tensile strength of approximately 1100 N / mm2. Fig. 2 shows the same wire fiber in plan view whereby the flattened end pieces are more visible.

EXAMPLE 1 The fiber described above was tested according to the Bündner guidelines BB2 - 711.100 (October 1998). Shotcrete with a cement content of 425 kg / m ³ according to CEM I 42.5) was used as the building material. A superplasticizer (Rheobuild 3520 from MBT) in a dosage of 1.2% (based on cement mass), a stabilizer (Delvo Stabi) in a dosage of 0.2% (based on cement mass) and 35 kg / m ³ steel fibers were used as additives used. The ready-to-use shotcrete had a consistency of 51.0 cm determined according to: slump (according to DIN 1048), a wet room weight of 2372 kg / m ³ , an LP content of 1.5% and a tool value: 0.52. The steel fiber content in the hardened concrete is determined using drill cores. A single value represents the mean of at least three drill cores extracted within 1m ^2. The drill core length must be over 5 cm. The sample quantity for determining a single value must not be less than 5 kg. Four test specimens in the form of drill cores with a diameter of 100 mm were tested.

Findings:

The sample examined has an average steel fiber content of 30.4 kg / m ^{3 of} concrete.

EXAMPLE 2

In this case the same concrete was used, but 40 kg / m ³ steel fibers were used. The ready-to-use shotcrete had a consistency of 54.0 cm determined according to: slump (according to DIN 1048), a wet room weight of 2398 kg / m ³ , an LP content of 1.7% and a tool value: 0.50.

Four test specimens in the form of drill cores with a diameter of 100 mm were tested.

Findings:

Concrete on.

EXAMPLE 3 Under the same conditions as in Example 2, a known FE 0730 fiber (40 kg / m3) from the applicant was tested. These fibers are essentially straight and have two flattened ends. The sample examined has an average steel fiber content of 29.5 kg / m ^{3 of} concrete, ie a loss of 26%.

EXAMPLE 4

Fibers of type HE 07/30 from the applicant were tested under very similar conditions as in Examples 2 and 3 (40kg / m3). These fibers have a middle piece, two kinked intermediate pieces connected to the middle piece and in each case one end piece connected to the intermediate piece, the end piece being kinked relative to the intermediate piece in such a way that the end piece is essentially parallel to the middle piece. However, the end piece is round and, unlike the fiber according to the invention, is not flattened.

The sample examined has an average steel fiber content of 25.7 kg / m ^{3 of} concrete, ie a loss of 36%.

Claims

claims

1. Metal wire fiber for use in the reinforcement of mouldable materials, in particular concrete, which has a center piece, two kinked intermediate pieces connected to the middle piece and one end piece connected to the intermediate piece, the end piece being kinked relative to the intermediate piece in such a way that the end piece essentially parallel to the middle piece is characterized in that the end piece is partially flattened.

2. Wire fiber according to claim 1, characterized in that the middle piece and the intermediate piece have a substantially circular cross section.

3. Wire fiber according to claim 1 or 2, characterized in that the end pieces and the middle piece lie in a plan.

4. Wire fiber according to claim 1 or 2, characterized in that the intermediate pieces are kinked in one direction.

5. Wire fiber according to one of the preceding claims, characterized in that the wire fiber has a length of about 10 to 70 mm, a maximum diameter of up to about 1.3 mm.

6. Wire fiber according to one of the preceding claims, characterized in that the intermediate piece and the end piece have a length of

5 to 20 times the diameter of the wire fiber.

7. Wire fiber according to one of the preceding claims, characterized in that the end piece has a length (I, I ') of 2 to 10 times the diameter of the wire fiber.

8. Wire fiber according to one of the preceding claims, characterized in that the flattened end piece has a width (B) of 1.5 to 3.5 times the diameter of the wire fiber.

9. Wire fiber according to one of the preceding claims, characterized in that the intermediate piece has a height (h, h ') of 2 to 10 times the diameter of the wire fiber.