RU2579053C2 - Nonmetallic reinforcing element with periodic surface and method of producing nonmetallic reinforcing element with periodic surface - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to a reinforcing element for concrete structures. Non-metallic reinforcing element with a periodic surface is made as a braid, woven from high-strength mineral bundles with pre-twisting thereof. Weave method is carried out with an angle pigtail harness to longitudinal axis of element in range 10-85°. Impregnated reinforcing element is subjected to thermal polymerisation, if necessary, and cooling.

EFFECT: technical result is improving product quality, increasing strength characteristics due to additional twist yarns during manufacture of non-metallic reinforcing element, and maximising value of coupling non-metallic reinforcement from concrete matrix due to configuration of profile fixtures without additional winding different strands onto surface of reinforcing member.

3 cl, 4 dwg

Description

The present invention relates to construction, namely to reinforcing elements for prefabricated and monolithic, non-stressed and prestressed concrete structures, for use in structural elements of buildings in the form of separate rods, flat grids and spatial frames, for reinforcing the foundations of buildings, structures and piles, including the foundations of motorways and roads; for reinforcing retaining walls and structures.

Known reinforcing element for prestressed concrete structures aimed at creating a high-tech non-metallic reinforcing element for prestressed concrete structures with the possibility of tensioning it with a force of up to 400-1000 MPa, with an increased tensile modulus, fire resistance and a high degree of adhesion to the concrete matrix, and also reducing the complexity of the formation of end anchor grips [1].

The disadvantages of the known method of manufacturing a reinforcing element are not sufficiently high strength and tensile modulus of the reinforcing element, due to the fact that the roving made of continuous mineral fibers assembled in a tape bundle is not intertwined, twisted, but only glued with an epoxy impregnating mass or cement binder , the moment of possibility of uneven work of rovings inside the tourniquet is not ruled out.

Known composite reinforcing element, composite reinforcement (options). The composite reinforcement contains a support rod made of high-strength polymeric material, in which the surface relief is created by a winding bundle, the ratio of the cross-sectional areas of the supporting rod and the winding bundle being in the range from 3 to 25, the winding bundle in cross section has the shape of an ellipse, the major axis of which is located along the supporting rod and the winding angle is 30-70 °, the relief can also be formed by pressing a removable winding harness into the bearing rod, and the grooves in cross section have the inverse profile of the winding harness, and the ratio of the cross-sectional areas of the bearing rod and removable winding harness are in the range from 3 to 25 [2].

The disadvantages of the known method of manufacturing a reinforcing element is a low degree of adhesion to concrete due to the lack of a periodic profile of the rod itself, which should be compensated by additional winding of the winding bundle fastened with a polymer binder.

Closest to the proposed manufacturing method and the reinforcing element are a method of manufacturing a non-metallic reinforcing element with a periodic surface and a reinforcing element with a periodic surface [3], consisting of longitudinally arranged bundles made of long mineral fibers or threads from them, in the form of a tape, they are arranged in the longitudinal direction and weave into the rope single or double weaving.

To ensure better adhesion to the concrete matrix, anchor devices are placed on the longitudinal shaft in increments of 0.5-1.5 m, which, during the weaving and passage of the bundles along them, change the angle of the bundles relative to the longitudinal axis, making the cross-section uneven.

The disadvantage of the element is the impossibility of uniformly tensioning the harnesses of the reinforcement and creating a uniform section relative to the axis of the element.

The objective of the invention is to improve the quality of the product, increase the strength characteristics due to the additional twisting of the bundles during the manufacturing process of the non-metallic reinforcing element and obtaining maximum values of the adhesion of the non-metallic reinforcement to the concrete matrix due to the configuration of the reinforcement profile itself without additional winding of the various bundles onto the surface of the reinforcing element.

This problem is solved in that a non-metallic reinforcing element with a periodic surface, comprising long braided mineral fiber bundles intertwined in the form of pigtails, impregnated with a polymer binder, characterized in that the pigtail is made of three, six or nine high-strength mineral fiber bundles, with preliminary twisting of the bundle or without it. In this case, the pigtail is woven from high-strength aramid or carbon tows. A method of manufacturing a non-metallic reinforcing element with a periodic surface includes placing, weaving together long mineral fiber bundles using the pigtail method and impregnating them with a polymer binder, characterized in that the weaving is made with the angle of the bundles to the longitudinal axis of the element within 10 ° -85 °, and the impregnated reinforcing element is thermopolymerized and cooled using heat-resistant binders

A non-metallic reinforcing element with a periodic surface consists of three, six or nine high-strength mineral fiber bundles (carbon, aramid fiber, and also possibly fiber glass and basalt fiber). The number of bundles is limited by the number at which the periodic surface of the reinforcing element becomes close to flat, i.e. the surface of the reinforcing element is smooth and does not have protrusions and depressions, it has been experimentally established that the use of more than 9 bundles leads to an undesirable smooth surface of the reinforcing element, such a surface has minimal adhesion to concrete, therefore the number of bundles used in the weaving of the reinforcing element is determined by three, six and nine, while obtaining the required diameter of the reinforcing element is determined by the thickness of the braid. The weaving of the harnesses is carried out in a special way of the “Pigtail” type with the angle of the harness to the longitudinal axis of the element ranging from 10 ° to 85 °, these angles are due to the data of the tests, which revealed that damage occurs at an angle of the harness less than 10 ° to the longitudinal axis fibers due to excessive bending during weaving and insufficient tension of the bundles themselves during the manufacturing process, in the case of arrangement of bundles with an angle greater than 85 ° to the longitudinal axis of the reinforcing element periodic profiles are not sufficient to ensure reliable adhesion to concrete structures. In the production of non-metallic reinforcing elements, the following types of carbon and aramid bundles are used, as well as possibly glass and basalt. Depending on the tasks and economic components (cost of output), the type of harness used is determined, so the most affordable non-metallic reinforcing element will be fiberglass, and the most durable of carbon fiber. In the process of manufacturing a non-metallic reinforcing element after the weaving operation, this element is coated with a binder. The resin impregnation process is determined in strict accordance with the requirements of the manufacturers of these binders with mandatory confirmation by laboratory tests of prototypes. Synthetic thermosetting resins, organosilicon or phenolic aldehyde, epoxy, which do not emit any by-products during polymerization, are used as a binder. It is also permissible to use highly heat-resistant resins - polyamide, polybenzimidazole, etc., which harden after heat treatment. The impregnated reinforcing element is subjected to heat-curing resins using thermopolymerization and cooling.

When the rod is woven, a relief surface is formed, which provides maximum adhesion to concrete due to the presence of a periodic profile. A distinctive feature of the proposed fittings from the known ones closest to it is that the surface relief of the rod is created by weaving the rod itself, by winding an additional bundle on it. As a result, a non-metallic reinforcing element is obtained at the output, in which a relief surface is formed due to the interweaving of the bundles. This design feature of the proposed composite reinforcement increases tensile and bending strength and increases adhesion to concrete.

The manufacture of composite reinforcement with improved tensile and bending strengths occurs due to the twisting of the harnesses during the weaving process. The manufacture of the reinforcing element is carried out with the preliminary twisting of the bundles by rotating the coil with the bundle during weaving, i.e. the weaving mechanism has a special device on which a coil with a bundle is attached, which rotates about its axis by twisting individual bundles, while the cross-section of the bundle increases in proportion to the degree of torsion, this method allows you to get an reinforcing element with higher tensile strengths up to 1465 MPa and elastic modulus up to 137 GPa. The tension of the harnesses is regulated by means of an adjustable tensioning mechanism and weaving of the element itself.

The method of obtaining the fittings is simple, technological, does not require the development of special equipment and does not require additional capital costs.

The invention is illustrated by figure 1, which depicts a non-metallic reinforcing element with a embossed surface, obtained by weaving three or more bundles. In FIG. 2 is a side view of a non-metallic reinforcing element. In FIG. 3 shows a production line for the production of a non-metallic reinforcing element. In FIG. 4 shows a diagram of the movement and rotation of coils with plaits in the process of weaving a non-metallic reinforcing element.

An example of a specific implementation.

Composite reinforcement consists of three six or nine fiber bundles of high-strength polymer material (for example, carbon fiber material of the UK-Argon brand according to TU 1916-214-51385208, aramid fiber material of the Ruslan-SVM-N brand according to TU 2272-018051605609) or fiberglass GOST 17139 -79, CBM grades according to TU 6-06-1153-78, basalt fiber material of the grade RBN 13-1250-4s or RBN 13-2500-4s according to TU 5952-001-13308094-04).

The manufacturing process of non-metallic reinforcing element (see Fig. 3) consists of the following technological operations:

Coils with a tourniquet (carbon fiber, aramid and, possibly, basalt and fiberglass); positioned at the attachment points on a braiding machine 1. Harnesses from a coil with a tow (carbon fiber, aramid and possibly basalt and fiberglass); they are placed in the attachment points on the braiding machine 1. The bundles from the coils are passed through the process ring - clamping mandrel 2, then through the impregnation bath shafts and squeeze shafts 3, they are passed into the heating chambers 4, from the heating chambers the bundles enter the cooling chamber 5 and then past the cutting disk tool 6 through the tension shaft 7, is fixed on the receiving drum 8. Binder is loaded into the impregnation bath, the required temperature is set in the heating (curing) chambers and the production line of reinforcing elements is launched. In this case, the braiding machine begins its rotation according to the figure eight, alternating coils with plaits, the skeleton of the reinforcing element is formed (Fig. 1). Next, the twisted bundles enter the impregnation bath, where the bundles are wetted with the above-mentioned binder, and the squeeze shafts remove excess binder. After impregnation, if necessary, depending on the type of binder, the bundles enter the heating chambers, where the polymerization process takes place under the influence of temperature, after the heating chambers, the reinforcing element passes through the cooling chamber, where the temperature drops to normal (no more than 30 ° C). A non-metallic reinforcing element, passing through a cutting disc tool, is wound on a drum, forming bays. If necessary, a cutting of the required length is done using a cutting disc tool. The non-metallic reinforcing element is ready for use.

In FIG. Figure 4 shows the movement pattern of coils with bundles (carbon fiber, aramid fiber, as well as fiberglass, basalt fiber) on a braiding machine, which move in the figure eight pattern, while the coils with a bundle rotate about its axis with a certain frequency, thereby twisting the bundle. The twisted bundle is further intertwined into a pigtail, forming a “skeleton” of the reinforcing element.

When testing a non-metallic reinforcing element, an increase in physical and mechanical properties was revealed in comparison with unidirectional rods, as well as the dependence of the strength characteristics of the element on the degree of twisting of the bundles during weaving. The proposed non-metallic reinforcing element has a high tensile, bending strength and, as a result, increases the bearing capacity of the building structure. As a result, using the same number of bundles, in comparison with unidirectional reinforcing bars, at the output we get a reinforcing element with strength indicators 10-20% higher due to twisting of the bundles about its axis and, as a result, an increase in the cross-sectional area. The average values of the strength parameters of composite reinforcement from different types of fibers are shown in table 1.

In the process of weaving, a periodic profile structure is formed that provides maximum adhesion of the surface to concrete. According to the test results in accordance with GOST 31938-2012, all samples were destroyed along the reinforcement bar, as a result of which it was found that the adhesion of the composite reinforcement with concrete exceeds the strength indices of the reinforcement itself.

Information sources

1. RF patent No. 2455436, E04C 5/07 from 12/15/2010, publ. 07/10/2012

2. RF patent No. 2287647, Е04С 5/07 of 03/21/2005, publ. November 20, 2006

Z. Patent of the Russian Federation No. 2482247, Е04С 5/07 dated 05/26/2011, publ. 05/20/2013

Claims (3)

1. Non-metallic reinforcing element with a periodic surface, including long braided mineral fiber bundles woven together in the form of pigtails, impregnated with a polymeric binder, characterized in that the pigtail is made of three, six or nine high-strength mineral fiber bundles, with preliminary twisting of the bundles. 2. Non-metallic reinforcing element according to claim 1, characterized in that the pigtail is woven from high-strength aramid or carbon bundles. 3. A method of manufacturing a non-metallic reinforcing element with a periodic surface, including placing, weaving together long-length mineral fiber bundles using a pigtail method and impregnating them with a polymer binder, characterized in that the weaving is made with the angle of the bundles to the longitudinal axis of the element within 10-85 °, and the impregnated reinforcing element when using heat-resistant binders is subjected to thermopolymerization and cooling.

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