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Title:
CONCRETE REINFORCEMENT FIBERS
Document Type and Number:
WIPO Patent Application WO/1997/043502
Kind Code:
A1
Abstract:
A fiber for use in reinforcing concrete, the fiber having an elongated body and at least one slit formed at either end of the elongated body, and a crimp being formed preferably on each side of the slit. The formation of the crimps with the slits therebetween allows the concrete to enter and when the fiber is then subjected to a tensile force, it will act to compress the concrete and impart a greater strength.

Inventors:
DRYA-LISIECKA KRYSTYNA (CA)
Application Number:
PCT/CA1997/000314
Publication Date:
November 20, 1997
Filing Date:
May 12, 1997
Export Citation:
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Assignee:
DRYA LISIECKA KRYSTYNA (CA)
International Classes:
E04C5/01; E04C5/07; (IPC1-7): E04C5/01
Foreign References:
DE2832495A11980-02-07
US3936278A1976-02-03
US5419965A1995-05-30
US4078940A1978-03-14
US3942955A1976-03-09
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Claims:
CLAIMS :
1. A fiber (10) for use in concrete, said fiber comprising an elongated body having a length, a width and a thickness, first (12) and second (14) ends, first (20) and second (22) opposed surfaces, first (14) and second (16) side walls extending along said length, said thickness being defined by a distance between said surfaces, (20, 22) an elongated slit (24) extending between said surfaces (20, 22) being formed adjacent at least one of said ends, and a crimp (26) being formed in said body adjacent said slit.
2. The fiber of Claim 1 including first and second crimps (26, 28) on either side of said slit (24) , said first and second crimps being formed to extend in opposed directions.
3. The fiber of Claim 2 comprising a slit being formed adjacent both of said ends, and first and second crimps being formed at both of said ends.
4. The fiber of Claim 1 wherein said body has a twisted configuration such that each of said surfaces follows an arcuate configuration.
5. The fiber of Claim 1 wherein each of said surfaces has a generally rectangular configuration in an untwisted mode.
6. The fiber of Claim 3 wherein said body is formed of a steel material.
7. The fiber of claim 3 wherein said body has a twisted configuration such that each of said surfaces follows an arcuate configuration.
8. The fiber of Claim 3 wherein said fiber has a length of between 50 mm and 75 mm.
9. The fiber of Claim 3 wherein said fiber has a width of between .5 mm and 4 mm.
10. The fiber of Claim 3 wherein said fiber has a thickness of between .1 mm and 2 mm.
11. The fiber of Claim 3 wherein said slit has a length of between 1 mm and 6 mm.
12. In a concrete mixture, the improvement wherein said concrete includes a plurality of fibers, said fibers being as defined in Claim 1.
13. In a concrete mixture, the improvement wherein said concrete includes a plurality of fibers, said fibers being as defined in Claim 2.
14. In a method for manufacturing concrete, the improvement comprising the step of incorporating in the concrete a plurality of dispersed fibers, said fibers comprising an elongated body having a length, a width, and a thickness, first and second ends, first and second opposed surfaces, first and second side walls extending along said length, said thickness being defined by a distance between said surfaces, an elongated slit extending between said surfaces and being formed adjacent at least one of said ends, and a crimp being formed in said body adjacent said slit.
Description:
CONCRETE REINFORCEMENT FIBERS

The present invention relates to a new cementious composite material having a fiber reinforcement and also relates to a new type of fiber for reinforcing cementious material and to a method for forming such cementious material.

The use of fibers for reinforcing concrete is well known in the art. Originally, it was suggested in the art that the tensile strength of concrete could be improved by adding longitudinally extending fibers of different materials including iron, wood, etc. Many suggestions have also been made in the art regarding the various configurations of the fibers - suggestions have included cylindrical bodies, undulating bodies, crimped structures etc. The most important factor in the choice of the fiber are the resulting improvements in the strength of the concrete. These improvements can depend on the characteristics of the fiber including various geometrical characteristics, its physical and chemical characteristics and mechanical strengths. While many of these various fibers have been shown in the past to improve the strength of the concrete, there is always an on going search for fibers which will further increase the concrete strength or improve other properties.

It is an object of the present invention to provide an improved fiber for use in reinforcing concrete.

It is a further object of the present invention to provide an improved concrete having a fiber reinforcement.

It is a further object of the present invention to provide a method of reinforcing concrete.

According to one aspect of the present invention, there is provided a fiber for use in concrete, the fiber comprising an elongated body having a length, a width and a thickness, first and second ends, first and second opposed surfaces, first and second side walls extending along the length, the thickness being defined by a distance between the surfaces, an elongated slit extending between the surfaces and being formed adjacent at least one of the ends, and a crimp being formed in the body adjacent the slit.

In a further aspect of the present invention, there is provided an improved concrete mixture wherein the improvement comprises a plurality of fibers dispersed in the concrete, the fibers comprising an elongated body having a length, width, and a thickness, first and second ends, first and second opposed surfaces, first and second side walls extending along the length, the thickness being defined by a distance between the surfaces, an elongated slit extending between the surfaces and being formed adjacent at least one of the ends, and a crimp being formed in the body adjacent the slit. In a further aspect of the invention, there is provided an improvement in a method for manufacturing concrete, the improvement comprising the step of incorporating in the concrete a plurality of dispersed

fibers, the fibers comprising an elongated body having a length, a width and a thickness, first and second ends, first and second opposed surfaces, first and second side walls extending along the length, the thickness being defined by a distance between the surfaces, an elongated slit extending between the surfaces and being formed adjacent at least one of the ends, and a crimp being formed in the body adjacent the slit.

In greater detail, the fiber of the present invention may be formed from many suitable materials including steel, glass, and synthetic materials such a polypropylene, kevlar, nylon, polyester, glass, etc.

The fiber of the present invention is of a configuration which provides an elongated body having a pair of opposed ends. The body, in a preferred embodiment, generally has an overall rectangular configuration when in an untwisted state although it will be understood that variations thereof may be employed. Thus, even a substantially circular cross sectional fiber could have a slit formed therein along with a crimp adjacent thereto.

In order to anchor the fiber and provide the maximum strength to the concrete, the fiber has a slit therein and a pair of crimps formed adjacent the slit to extend outwardly in opposite directions. Preferably, the slit and associated crimps are located adjacent both ends of the body although it will be understood that it would also be possible to utilize multiple locations.

The precise form of the crimp may vary; a convenient configuration is one wherein the crimp has a generally V-shaped configuration although a more uniform arcuate configuration could also be employed.

The formation of the crimps with the slit therebetween allows the entry of the concrete (while in a fluid state) between the crimped portions of the fiber. When the fiber is subjected to a tensile force, it will act to compress the concrete and thereby impart a greater strength thereto.

In a preferred embodiment, the body, which normally has an overall rectangular configuration, is twisted about its longitudinal axis. This twisting has been found to further add strength to the concrete. The amount of twisting will depend upon the material used for the fiber as one must take into account any damage to the material making up the fiber. In the case of steel fibers, a twisting of the fibers up to 180° has been found to be suitable.

The dimensions of the fiber may vary as may the precise configuration. In one embodiment, the fiber is illustrated as having a rectangular cross-sectional configuration although this can be varied to even approach a circular cross-sectional configuration.

In a preferred embodiment, the length of the fiber would vary between 12 mm and 105 mm with a particularly preferred length being between 50 and 75 mm.

The fiber will be referred to as having a width and a thickness although, as will be understood, the cross sectional configuration may be arcuate wherein thickness and width are substantially interchangeable. In preferred embodiments, the fiber will have a width of between .5 mm and 4 mm and a thickness of between .1 mm and 2 mm. If one were to calculate a cross sectional area equivalent to a bound cross sectional fiber, one could employ aspect ratios of between 20 and 75 and preferably between 30 and 50.

In a preferred embodiment, the length of the slit could vary between 2 mm and 15 mm with the crimp extending outwardly from the main plane of the body for a distance of between 2 mm and 10 mm.

The fibers may be incorporated in the concrete by conventional means. The proportion can preferably vary between 20 to 120 kilograms/meter.

Having thus generally described the invention, reference will be made to the accompanying drawings illustrating an embodiment thereof, in which:

Figure 1 is a perspective view of a fiber according to the present invention;

Figure 2 is a detailed view of the fiber ends;

Figure 3 is a perspective view of the fiber twisted through 90°; and

Figure 4 is a perspective view of the fiber of Figure 1 twisted through 180°.

Referring to the drawings in greater detail and by reference characters thereto, there is illustrated a fiber which is generally designated by reference numeral 10 and which is preferably formed of a steel material.

Fiber 10 has a body which is of a generally elongated configuration and has a first end 12 and a second end 14.

There are a pair of parallel side walls with a first side wall being designated by reference numeral 16 and a second side wall being designated by reference numeral 18. Extending between side wall 16 and 18 are a pair of opposed major planar surfaces 20 and 22 respectively.

As shown in detail in Figure 3, at end 12 there is provided a slit 24 extending generally along the longitudinal axis of the fiber. Slit 24 extends a relatively short distance compared to the overall fiber length designated by reference character L.

At slit 24 there is formed a first crimp 26 and a second crimp 28; as will be noted, crimps 26 and 28 extend in substantially opposite directions - i.e. one extends outwardly from major surface 20 and the second extends outwardly from major surface 22.

Second end 14 also has a slit end crimp structure which is substantially identical to that described with respect to first end 12.

In the preferred embodiments, the fiber is twisted along its longitudinal axis. In this respect, Figure 3

shows the fiber twisted through 90° while in Figure 4, the fiber is twisted to 180° along its longitudinal axis.