EP1364094A1

EP1364094A1 - Reinforcing bar and method for the production thereof

Info

Publication number: EP1364094A1
Application number: EP02712807A
Authority: EP
Inventors: Alexander Bleibler
Original assignee: Sika Schweiz AG
Current assignee: Sika Technology AG
Priority date: 2001-02-21
Filing date: 2002-01-09
Publication date: 2003-11-26
Also published as: JP2004526887A; CN1526047A; DE10108357A1; WO2002066762A1; US7045210B2; CN1262719C; US20040065044A1

Abstract

The invention relates to a reinforcing bar for mineral building materials, particularly for cement. The inventive reinforcing bar (10) is made of a bar of plastic material reinforced by fibre, which has a central, elongate core (12) and several ribs (14) which extend along the length of the core, which are disposed at an angular distance from each other, which form a cross or a star in the cross section thereof and which are twisted around the core axis (16) in a helical manner.

Description

Reinforcing bar and method for its production

description

The invention relates to a reinforcing bar for mineral building materials, in particular for concrete, and a method for its production.

Components such as B. ceilings or beams, must absorb pressure, tensile and shear forces. For this reason, such components are usually made of reinforced concrete or prestressed concrete. Concrete is subjected to pressure and steel to tension. The bars or necessary for the reinforcement or reinforcement of the concrete. Up to now, wires have mainly been made from steel. Steel has the advantage that it is chemically compatible with concrete. A disadvantage, however, is the susceptibility to corrosion due to rust formation. If rust occurs, the concrete flakes off the reinforcing bar, which can lead to damage and destruction. This requires constant inspection and repair of reinforced concrete structures.

To avoid this, it has already been proposed to coat the steel with synthetic resin, for example with epoxy resin. It has been shown, however, that if the synthetic resin coating is damaged, spot corrosion at rust spots develops which progresses rapidly. Another disadvantage of coated steel reinforcement is the low adhesion between concrete and reinforcement. The form fit on the surface ribs of the reinforcing bars is not sufficient due to the lack of an adhesive bond.

Proceeding from this, the object of the invention is to develop a reinforcing bar for mineral building materials, in particular for concrete, which is easy to manufacture and securely anchored in the building material and which can be transported and assembled without risk of damage. To achieve this object, the combinations of features specified in claims 1 and 15 are proposed. Advantageous refinements and developments of the invention result from the dependent claims.

An idea essential to the invention is that the reinforcing rod is formed by a fiber-reinforced plastic strand which has a central elongated strand core and a plurality of strand ribs which are arranged at an angular distance from one another and which extend over the length of the strand core and which protrude in cross-section in a star or cross shape the core axis are continuously helically twisted. The strand ribs expediently project over the core surface by at least one rib width corresponding to the core diameter. The helical winding of the strand ribs results in a form-fitting anchoring of the reinforcing bars in the concrete. In order to be able to absorb the desired tensile forces, at least some of the reinforcing fibers are designed as longitudinal fibers that run continuously along the strand and are aligned axially parallel in the core area and in the rib area in the upward direction of the strand ribs. The individual reinforcing fibers formed as longitudinal fibers in the rib region expediently run at a constant distance from the core axis.

In order to enable reliable handling of the reinforcing bars on the construction site, the strand is additionally reinforced with transverse or circumferential fibers, at least in the area of the strand ribs. The transverse fibers prevent the grooves between the strand ribs from buckling or sagging when the reinforcing bars are stacked on top of one another during transport and when walking on. Due to the helically twisted strand ribs, contact points are formed at sufficiently short intervals when the bars are layered one on top of the other, which ensure that no deformation occurs under load. The latter is also in the assembled state important if the reinforcing bars are laid criss-cross. While the longitudinal fibers in the reinforcing bars have the function of tensile reinforcement, the transverse fibers have the function of kink reinforcement. A preferred embodiment of the invention provides that the strand ribs are arranged at equal angular distances from one another and that the strand ribs are twisted with a constant pitch. In principle, however, it is also possible to twist the strand ribs along the strand with a variable pitch. The pitch angle of the strand ribs relative to the core axis can be set and optimized within relatively wide limits. It is expediently between 15 and 75 °, preferably 30 to 50 °.

The longitudinal and transverse fibers suitably form a woven or non-woven fabric. The reinforcing fibers are advantageously selected from the group consisting of carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers, basalt fibers, natural fibers or from a mixture of these fibers. Because of the chemical compatibility with concrete, the reinforcing fibers are expediently chosen as carbon fibers near the surface of the strand, while the cheaper glass fibers and the like can also be used in deeper layers of the interior of the strand.

The plastic matrix of the strand can consist of a thermosetting polymer material, preferably from the group of epoxy resin, polyester resin, vinyl resin. In order to make it easier to deform the strand during the manufacturing process, it may be advantageous if the plastic matrix made of a thermoplastic, preferably from the group polyamide (PA), polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polypropylene (PP), polyethylene terephthalate ( PET), polybutylene terephthalate (PBT), polyetherimide (PEI), styrene polymer (ABS), polyether ether ketones (PEEK). The method for producing the reinforcing bars according to the invention essentially consists in twisting and cutting a fiber-reinforced plastic strand with a star-shaped or cruciform cross-section in a helical manner.

In principle, it is possible to embed a fiber or fabric insert in the plastic strand in the course of its manufacture using the pull-trusion method.

For the production of the plastic strand according to the invention, a prefabricated, plate, tape or tube-shaped starting material made of fiber-reinforced plastic is formed, preferably folded, to form a cross-shaped or star-shaped strand, and then twisted and cured helically. It is particularly advantageous if the sheet, strip or hose material containing a thermoplastic as a binder matrix is shaped into the fiber-reinforced plastic strand under the action of pressure and heat. At least two layers of different fiber materials can be used in the production of the fiber reinforcement in the plate, tape or tube-shaped starting material, an outer layer advantageously consisting of carbon fibers.

The invention is explained in more detail below on the basis of the exemplary embodiments shown schematically in the drawing. Show it

Fig. 1a and b a cross-section reinforcing bar before and after the helical twist in a graphical

Presentation;

Fig. 2a to c a plate or ribbon-shaped starting material (Fig. 2a) and a tubular starting material (Fig. 2b) for Production of a cross-shaped twisted reinforcing bar (Fig. 2c) in a diagrammatic, partially broken representation.

The reinforcing bars shown in the drawing are intended for the reinforcement of concrete components.

The reinforcing rod 10 consists of a fiber-reinforced strand of plastic which has a central, elongated strand core 12 and a plurality of strand ribs 14 which are arranged at an angular distance from one another over the length of the strand core and which project in a star or cross shape in cross section. The starting product is, for example, the strand structure 10 ′ shown in FIG. 1 a, the strand ribs 14 of which are twisted helically around the core axis 16 in the same direction and with the same pitch to form the reinforcement rod shown in FIG. 1 b. Some of the reinforcing fibers are designed as longitudinal fibers 18. In the end product according to FIG. 1 b, the longitudinal fibers 18 in the core region run parallel to the core axis 16, while in the region of the strand ribs 14 they are aligned parallel to the ribs, that is to say in the direction of slope of the strand ribs 14. The individual longitudinal fibers 18 in the rib region have a constant distance from the core axis 16 over their entire length. The longitudinal fibers 18 within the reinforcing rod 10 have the primary task of absorbing tensile forces. The twisting of the strand ribs 14 results in a stable positive fit within the concrete, which despite the otherwise smooth surface of the reinforcing bar prevents the reinforcing bar 10 from being released from the bond with the surrounding concrete.

Another part of the reinforcing fibers 20 runs essentially transversely to the longitudinal fibers 18 within the strand structure. This is also the case in the region of the strand ribs 14. The cross fibers 20 form a kink reinforcement, the transverse forces acting on the reinforcing bar 10 can absorb to reduce the risk of kinking. In the exemplary embodiment shown in FIG. 1 b, the pitch angle of the strand ribs 14 is approximately 30 to 40 ° relative to the core axis 16. Since a total of four strand ribs are provided here, when the reinforcing bars are stacked on top of one another, there are sufficiently short support lengths between two support points, which counteract a load or when a deflection is caused.

2a to c indicate schematically that for the production of the reinforcing bars with a cross-shaped cross-section, plate-like or band-shaped starting material 10 "(FIG. 2a) or tubular starting material 10 '" (FIG. 2b) can also be used.

There are various possibilities for the production of the plate-like or band-shaped starting material 10 ″. In the so-called roll trusion process, individual threads, fabrics or scrims are pre-impregnated and passed through a roller press. A thin strip is produced which is still relevant for the purposes relevant here This is why several tapes have to be placed on top of one another and connected to one another by heating and fusing. Tapes with different reinforcing inserts such as carbon fiber or glass can also be used. The tapes prefabricated in this way are finally heated, folded into a cross and One disadvantage of this procedure is the relatively slow production speed, and only high-quality thermoplastics, such as polyamides, can be used for the binder matrix.

Another possibility for the production of plate material is that prefabricated fabrics and scrims are impregnated with a binder and fed to a double belt press. The fabrics or scrims can be combined from different fibers and made of relatively thick be educated. The result is an endless plate material 10 ", which can be deformed and twisted, for example, into the desired cross shape at elevated temperature. The difference to the roll trusion process is that it is assumed that a finished fabric and scrim with sufficient wall thickness, so that not several plates Thermoplastic from the group polyamide (PA), polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetherimide can be used as binders (PEI), styrene polymer (ABS), polyether ether ketones (PEEK) The material is first heated up in the double belt press and gradually cooled over the length of the press, so that material that has already hardened comes out at the end in the high production speed, including the variability in the fibers and in the binder materials allow cost optimization.

There are also various options for producing the tubular starting materials according to FIG. 2b:

In the pulltrusion process (continuous drawing), impregnated continuous fibers are pulltruded over a mandrel. This can be done in several stages, and a cross winding can also be applied after each process stage. In this case, a tube 10 '"with longitudinal and transverse fibers is obtained, the fibers also being able to be made of different materials, such as carbon fibers on the outside and glass on the inside. The tube is then subsequently heated, pressed to the cross and twisted.

2b, impregnated braided hoses made of the desired fiber material can also be used for the manufacture of the hoses. Braided hoses are first produced in the form of a fiber hose in braiding machines and subsequently impregnated with the binder. The impregnated tube is then pressed again in a cross shape and twisted. In principle, it is also possible to first deform the braided hoses in a cross shape and only then to impregnate them.

In summary, the following can be stated: The invention relates to a reinforcing bar for mineral building materials, in particular for concrete. The reinforcing rod 10 according to the invention consists of a fiber-reinforced strand made of plastic, which has a central, elongated strand core 12 and a plurality of strand ribs 14 which extend over the length of the strand core and are arranged at an angular distance from one another and have a star-shaped or cruciform cross section and which extend around the core axis 16 are helically twisted.

Claims

claims

1. Reinforcing bar for mineral building materials, especially for concrete, characterized by a fiber-reinforced strand (10) made of plastic, which has a central elongated strand core (12) and several extending over the length of the strand core, arranged at an angular distance from one another, with a star or cross-section has cruciform projecting ribs (14) which are helically twisted about the core axis (16).

2. Reinforcing bar according to claim 1, characterized in that at least some of the reinforcing fibers are designed as longitudinal fibers (18) which run continuously along the strand (10) and are aligned axially parallel in the core region and in the rib region in the direction of the slope of the strand ribs (14).

3. Reinforcing bar according to claim 2, characterized in that the individual longitudinal fibers (18) in the rib region run at a constant distance from the core axis (16).

4. Reinforcing bar according to one of claims 1 to 3, characterized in that the strand (10) is additionally reinforced with transverse fibers (20) at least in the region of the strand ribs (14).

5. Reinforcing bar according to one of claims 1 to 4, characterized in that the strand ribs (14) are arranged at equal angular intervals from one another.

6. Reinforcing bar according to one of claims 1 to 5, characterized in that the strand ribs (14) are twisted with a constant pitch.

7. reinforcing bar according to one of claims 1 to 5, characterized in that the strand ribs (14) along the strand (10) are twisted with a variable pitch.

8. Reinforcing bar according to one of claims 1 to 7, characterized in that the pitch angle of the strand ribs (14) relative to the core axis is 5 to 75 °, preferably 30 to 50 °.

9. Reinforcing bar according to one of claims 1 to 8, characterized in that the strand ribs (14) project beyond the core surface by at least one rib width corresponding to the core diameter, preferably twice the core diameter.

10. Reinforcing bar according to one of claims 1 to 9, characterized in that the reinforcing fibers (18, 20) are selected from the group consisting of carbon fibers, glass fibers, aramid fibers, high-strength polyethylene fibers, basalt fibers, natural fibers or from a mixture of these fibers.

11. Reinforcing bar according to claim 10, characterized in that the reinforcing fibers are formed as carbon fibers at least near the surface of the strand.

12. Reinforcing bar according to one of claims 4 to 11, characterized in that the longitudinal and transverse fibers (18, 20) form a woven or non-woven fabric.

13. Reinforcing bar according to one of claims 1 to 12, characterized in that the plastic matrix of the strand (10) from one thermosetting polymer material, preferably from the group consisting of epoxy resin, polyester resin, vinyl ester resin.

14. Reinforcing bar according to one of claims 1 to 12, characterized in that the plastic matrix of the strand (10) made of a thermoplastic plastic, preferably from the group polyamide, polymethyl methacrylate, polyphenylene sulfide, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyether imide, styrene - Polymer, polyether ether ketone exists.

15. A method for producing reinforcing bars for mineral building materials, in particular for concrete, characterized in that a fiber-reinforced plastic strand (10) with a star or cross-shaped cross section is helically twisted and cut to length.

16. The method according to claim 15, characterized in that a fiber or fabric insert is embedded in the plastic strand (10) in the course of its manufacture.

17. The method according to claim 15, characterized in that a prefabricated plate, tape or tube-shaped starting material (10 ", 10 '") made of plastic to form a cross-shaped or star-shaped strand (10') preferably by folding and pressing is reshaped and then helically twisted and cured.

18. The method according to any one of claims 15 to 17, characterized in that the plate, tape or tube material (10 ", 10 '") containing a thermoplastic as a binder matrix under the action of pressure and heat in the fiber-reinforced plastic strand (10) is reshaped.

19. The method according to any one of claims 15 to 18, characterized in that a thermoplastic material from the group polyamide, polymethyl methacrylate, polyphenylene sulfide, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyetherimide, styrene polymer, polyether ether ketones is used as the starting material for the binder matrix ,

20. The method according to any one of claims 15 to 19, characterized in that a fiber material from the group consisting of carbon fibers, glass fibers, aramid fibers, fibers made of high-strength polyethylene, basalt fibers, natural fibers is used as the starting material for the fiber reinforcement.

21. The method according to any one of claims 17 to 20, characterized in that at least two layers of different fiber materials are used in the manufacture of the fiber reinforcement in the plate, tape or tube-shaped starting material (10 ", 10" ').

22. The method according to claim 21, characterized in that at least one outer layer of carbon fibers is used.