WO1995011861A1

WO1995011861A1 - Reinforcement fiber package and related method

Info

Publication number: WO1995011861A1
Application number: PCT/US1994/012321
Authority: WO
Inventors: W. Wayne Freed; Frank L. Hollowell, Jr.; Dennis J. Hogan
Original assignee: Synthetic Industries, Inc.
Priority date: 1993-10-29
Filing date: 1994-10-28
Publication date: 1995-05-04
Also published as: AU8093394A; CA2174353A1

Abstract

A package (10) providing reinforcing fibers (20, 25) for a concrete mixture. The package comprises a first plurality of reinforcing fibers (20) and a non-paper container (12) therefor manufactured from a fabric formed from a second plurality of fibers (25), the fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the first plurality of reinforcing fibers and providing the second plurality of reinforcing fibers to the cementitious materials. Fiber-reinforced concrete mixtures comprise a preselected amount of cementitious material and at least one package of reinforcing fibers mixed therewith comprising a first plurality of reinforcing fibers and a non-paper container therefor manufactured from a fabric formed from a second plurality of reinforcing fibers, the fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the first plurality of discrete reinforcing fibers and providig the second plurality of reinforcing fibers to the cementitious materials. The present invention also pertains to a package for admixtures added to cementitious materials and methods for adding admixtures or a plurality of reinforcing fibers to cementitious materials.

Description

REINFORCEMENT FIBER PACKAGE AND RELATED METHOD

TECHNICAL FIELD The present invention relates to a package providing fibers for the reinforcement of concrete. The package skin is designed to be disintegratable within the concrete mixer thereby eliminating the need to open the package, pour in the fibers and subsequently discard it. Moreover, the package skin is manufactured from a non-woven manmade fiber or blend fabric which provides additional fibers for reinforcing the concrete upon addition.

BACKGROUND ART

Discrete fibers have been employed heretofore in the reinforcement of concrete as set forth in U.S. Pat. No. 3,645,961. The patent discloses the use of nylon, polyvinyl chloride and simple polyolefins in lengths ranging between one- quarter to three inches (0.6 to 7.5 cm) to form a blast resistant concrete.

Actually, polypropylene fibers have been used to modify the behavior of concrete for over 20 years. Reductions in water permeability and crack formation have been noted, as well as improvements in toughness, ductility, and impact resistance. Steel fibers have also been used for this purpose with limited success. Nevertheless, the fiber reinforcements have been typically provided in containers or packages which must first be opened so that the contents can be added to the concrete, as it is being mixed, in order for the fibers to be evenly distributed throughout the mixture. While pre-measured amounts are available for addition per cubic yard or other unit, and these can be added at the job site or at the ready mix plant, the procedure is time-consuming and provides waste as the package is discarded.

One alternative to the use of such discardable bags is described in U.S. Pat. No. 5, 120,367 which teaches the use of water-soluble materials, such as polyvinyl alcohol and polyethylene oxide, to form the container for various concrete admixtures. For use, the admixture package is added directly to concrete and the admixture is released as the water-soluble container dissolves.

The problem with this type of container is that it is susceptible to attack by moisture and water, prior to use, and thus others have employed paper bags as containers. U.S. Pat. Nos. 5,203,629 and 5,224,774 represent this teaching, disclosing the packaging of admixture materials, and fibers alone, respectively, in closed paper packages which disintegrate under the influence of mechanical action in a concrete mixture.

While reinforcing fibers and the like have heretofore been packaged in water-soluble films and paper bags, the art has not disclosed the use of a container material that will itself reinforce concrete.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide a package containing a plurality of fibers for reinforcing cementitious materials.

It is a further object of the present invention to provide a package that is disintegratable within apparatus for mixing cementitious materials.

It is another further object of the present invention to provide a package containing a plurality of fibers for reinforcing cementitious materials, which package is disintegratable within mixing apparatus into a second plurality of reinforcing fibers.

It is still another object of the present invention to provide a package for receiving reinforcing fibers and admixture materials as are added to cementitious materials.

It is still a further object of the present invention to provide a package for receiving reinforcing fibers and admixture materials, as are added to cementitious materials, which package is disintegratable within mixing apparatus into a plurality of reinforcing fibers.

It is yet another object of the present invention to provide a package containing a plurality of fibers for reinforcing cementitious materials which does not require opening individually by hand to release the fibers and, which does not create any waste for disposal. lt is still another object of the present invention to provide a method for the addition of fibers to cementitious materials.

These and other objects, together with the advantages thereof over the means for adding fibers to concrete mixtures, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.

In general, the present invention is directed toward a package providing reinforcing fibers for a cementitious material which comprises a first plurality of reinforcing fibers and a non-paper container therefor manufactured from a fabric formed from a second plurality of reinforcing fibers, the fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the first plurality of reinforcing fibers and providing the second plurality of reinforcing fibers to the cementitious materials.

A fiber-reinforced cementitious material is also provided which comprises a preselected amount of cementitious material and at least one package providing reinforcing fibers mixed therewith comprising a first plurality of reinforcing fibers and a non-paper container therefor manufactured from a fabric formed from a second plurality of reinforcing fibers, the fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the first plurality of reinforcing fibers and providing the second plurality of reinforcing fibers to the cementitious material.

The present invention also provides a package for admixtures added to cementitious materials comprising a non-paper container manufactured from a fabric formed from a plurality of reinforcing fibers, the fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the admixtures and providing the plurality of reinforcing fibers to the cementitious materials.

The present invention also provides a method for the addition of a plurality of fibers to cementitious materials which comprises the steps of introducing at least one package providing a first plurality of reinforcing fibers and a non-paper container, manufactured from a fabric formed from a second plurality of reinforced fibers, to a quantity of cementitious material; and mixing the cementitious material in apparatus with sufficient agitation to shred the container, releasing the first plurality of reinforcing fibers and providing the second plurality of reinforcing fibers to the cementitious material. The present invention also provides a method for the addition of an admixture to cementitious materials which comprises the steps of introducing at least one package providing the admixture and a non-paper container, manufactured from a fabric formed from a plurality of reinforced fibers, to a quantity of cementitious material; and mixing the cementitious material in apparatus with sufficient agitation to shred the container, releasing the admixture and providing the plurality of reinforcing fibers to the cementitious material.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of the package of the present invention, a portion thereof being broken away to depict the reinforcing fibers contained therein; and

Fig. 2 is a graph schematically depicting 25 fiber designs that form a mixture of graded fibers that can be employed with the present invention.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

The present invention relates to a special package of reinforcing fibers which is added directly to apparatus for mixing cementitious materials. Cementitious materials, as used herein includes without limitation precast products, mortar, grout, shotcrete, cast in place concrete, stucco and the like, all of which generally comprise hardenable cement-like materials. The terms concrete or concrete mixtures shall be employed herein with the understanding that all types of concrete products and cementitious materials are included such as those listed hereinabove. Reinforcement of concrete mixtures with fiber reinforcement is well known. The important functions of fiber reinforcement include: reduction of plastic shrinkage; increased abrasion resistance; reduced concrete permeability; increased concrete durability and toughness; improved post-crack performance and, improved impact and fatigue resistance by providing shock absorbency.

The fibers that are added to the concrete mixture can be selected from the broad class of commercially available thermoplastic polymers and copolymers as well as fiberglass, suitably coated; carbon fibers and steel fibers. Generally speaking, the fibers should neither affect the concrete nor be affected by the concrete and therefore, the fiber should not mold, rot mildew, dissolve or otherwise deteriorate in the concrete environment but should maintain its basic integrity throughout its useful life. Useful fibers include the polyolefins, such as polypropylene and polyethylene, the former being preferred; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides, such as nylon-6 and nylon-66, and aromatic polyamides, such as KEVLAR^®; polyacrylics, and the like, as well as fiberglass, suitably coated; carbon fibers, and even steel fibers, but should not be limited to these. Generally, polyolefins formed from monomers having from 2 to about 4 carbon atoms are employed because of their availability and cost although other polyolefins are not necessarily precluded. Practical considerations Include energy absorption, tensile strength and dispersibility of the fiber in the concrete mixture, although the absence of any one of these properties should not eliminate a particular polymer. Typically, thermoplastic fibers having specific gravities ranging from about 0.80 to 1.96 and fiberglass with a specific gravity range of about 2.50 to 2.70 are suitable. In addition, manmade cellulosic fibers such as rayon, acetate or triacetate can be employed in 100 percent form, formed as mixtures or blends with the foregoing synthetic polymer fibers and strands, as can fiberglass fibers and strands, carbon and steel fibers.

Configuration and shape of the fiber can be important, but neither is a controlling feature. The term fiber as employed herein shall be understood to include monofilament and multifiiament materials as well as slit films and sheets of synthetic materials which may also be fibrillated. Filamentary materials are not limited to cylindrical or round configurations but include all known cross-sectional configurations e.g., rectangular, square, round, oval, hollow, triangular, and the like. Additionally, tri-lobal multi-Iobal, fibrillated, collated, bonded fibrils, entangled monofilaments or monofilaments and roll embossed film fibers are other practical types for concrete reinforcement. Hence, it is customary to refer to the denier of the material i.e., the weight in grams of a 9000 yard length, rather than diameter. As is known, configuration of the filaments can also be straight, crimped, slubbed, spiraled, gear crimped, saw-tooth configured, gnarled, cork-screwed or otherwise deformed and all of these types are included.

The present invention provides for mixtures of fibers, as will be described in greater detail hereinbelow. It is to be understood that such mixtures encompass mixtures of one type of fiber, e.g. polypropylene, which is preferred, in different sizes; as well as mixtures of different fibers e.g., polyolefins and polyamides; and mixtures of different fiber configurations e.g., fibrillated materials and filamentary materials. In each instance, the mixture should also comprise a range of different fiber sizes, that is, the mixture should be graded. While all of the parameters, including different lengths, width, thicknesses, deniers, fibrillation, cross-sections and/or aspect ratios, need not be varied for each component of the graded mixture, it is to be understood that at least one or more parameters will vary between any two components.

Useful deniers range from about 0.5 to 8000 although broader ranges are not to be precluded. Preferred deniers range from about 340 to 2600. Similarly, the preferred lengths of the fibers range between about 0.125 to 2 inches (0.3 to 5.1 cm) although shorter and longer fibers, approximately 0.0625 and 3 inches (0.16 and 7.6 cm), respectively can be employed. Volume percentages of the shortest lengths range between about 2 to 4 percent; for the Intermediate lengths, between about 4 to 8 percent; and for the longest lengths, between about 2 to 3 percent, so as to total 100 percent by volume. Slit films and sheets will generally have thicknesses of from about 0.0001 to 0.01 inches (0.025 to 2.54 mm) and widths of from about 0.052 to 0.298 inches ( 1.32 to 7.57 mm) with 0.123 inches (3.12 mm) being preferred. Lengths are as noted hereinabove. Selection of the fiber designs for a mixture is related to the application. Generally speaking, mixtures of the shorter fibers are preferred for stucco and the like while the longer fibers are preferred for concrete.

As noted hereinabove, a mixture of fibers can be employed. Such mixtures are not necessarily random collections, but can instead be graded to accommodate the proportions and sizes of aggregate in the concrete. With reference to the drawing figures, Fig. 2 is a three-dimensional representation of the distribution of fiber deniers, cut lengths, and volume percentages for five preferred fiber sizes. Each of the five sizes, expressed in denier (its weight in grams for 9000 meters) is cut to five different lengths, from 0.40 to 0.85 inches. Thus there are 25 combinations of volume percent by denier and cut length. One can determine by Fig. 3, for example, that 2600 denier fiber, cut 0.50, 0.60 and 0.75 inches in length, each make up about 6 percent by volume of the total 100 percent.

The 25 different fiber designs are the preferred combination for practice of the invention where a mixture of fibers is packaged. In particular, it is preferred that the shortest and longest fiber lengths comprise a smaller percentage of the total, while the intermediate lengths make up the majority. Minimally, at least three different fiber designs should be mixed together for practice of the present invention. In this instance, selections should be made from each end of the range as well as one from the middle e.g., fiber lengths of 0.4, 0.6 and 0.85 inches or the like. At the minimum range, the three different fiber designs selected are combined to provide 100 percent by volume of the graded fiber mixture. Preferably, more than three designs are combined, those selected being present in amounts of from about 2 to 8 percent by volume of the graded fiber mixture.

In Fig. 2, if the individual data points were presented as a cumulative distribution, the volume of each fiber length would describe one half of a bell-shaped curve. Similarly, a cumulative distribution of each fiber denier would describe one half of a bell-shaped curve. For a more detailed explanation regarding the use of graded fiber mixtures, reference can be make to co-pending application U.S. Ser. No. 08/ , owned by the Assignee of record herein, the subject matter of which is hereby incorporated by reference. With respect again to the present invention, whereas these fibers have heretofore been provided in bags which must be opened, emptied and then discarded, the present invention provides a complete package that is readily disintegratable within the concrete mixture, eliminating the need to open and subsequently discard. The package material is manufactured from a fabric formed from fibers. Selection of the package material is made on the basis that it will maintain acceptable dry strength for handling and shipping, but when exposed to agitation within the concrete mixer, providing water and shear action, it will rapidly loose strength and disintegrate in the concrete, releasing the contained fiber reinforcement into the mix.

The package itself can be of various configurations which include, for instance, bags, envelopes, pillows, sleeves, cylinders, boxes, clamshells and the like, all of which must be of such size to fit into the opening of a concrete mix truck or related apparatus. The package material Is constructed from continuous strand polymer fibers or discontinuous discrete fibers. Both types are manufactured via conventional means for synthetic polymers such as polyolefins, nylons and polyesters, as disclosed hereinabove, or steel fibers or carbon fibers or any of the other polymers disclosed hereinabove which are selected as the additive fiber reinforcement, including mixtures and blends thereof. In addition, manmade cellulosic fibers such as rayon, acetate or triacetate can be employed in 100 percent form, formed as mixtures or blends with the foregoing synthetic polymer fibers and strands, as can fiberglass fibers and strands and steel and carbon fibers. All suitable fiber materials to form the package generally fall within the specific gravity range of 0.80 to 2.70. Continuous strand polymer fibers are typically melt spun and when cast upon a movable conveyor belt, a random, non woven fabric is formed, suitable for use as the package material. Discontinuous discrete fibers are deposited on a movable belt and then bonded together with a suitable binder such as a non cross- linked acrylic binder to produce a fabric, but not necessarily limited to such binders. Fabrics from either source of fiber type are then cut to form the package which, for example, may be a bag, or any other suitable container. Dimensions of a typical bag are approximately 14" by 18" (35.5 cm x 45.7 cm) to contain 1.5 pounds (0.675 kg) of reinforcing fiber and suitable dimensions to contain other reinforcing fiber dosages. Bag dimensions may be varied as dictated by packaging procedures, required bulk densities, and the like. Other types of containers may be, but are not limited, to pillows, cylinders, clamshells, boxes, soft boxes, and the like. Forming and sealing the container made from manmade or fiberglass fibers or strands is dependent on the container structure and make-up. Preferable methods may be heat sealing, gluing, bonding with an adhesive ultra-sonic sealing, folding, perforation, sewing, thermoforming, merely wrapping the contents, but are not limited to these procedures or methods. Bonding with a water soluble adhesive, binder, cement or the like is preferred.

With reference to the drawings, a package, according to the present invention, is depicted in Fig. 1 as a bag, indicated generally by the numeral 10. The package comprises an outer, non-paper, disintegratable fabric forming a container 12, having a sealed base 13 and a mouth 1 4 which is sealed at 1 5 after filling, and a first plurality of reinforcing fibers 20.

Unlike the prior art, which employs water-soluble films for bags, or non- water soluble paper, which merely disintegrates into small fragments of paper and paper pulp, the package of the present invention produces a second plurality of fibers 25 that is unexpectedly large. Taking as an example a bag measuring 14" x 1 8" x 2" or 504 square inches in area, we have calculated the number of fibers at approximately 1.25 inch lengths to range from about 5 x 10⁵ to 2.1 x 10⁶ per package, depending upon denier of the fiber and weight of the fabric forming the package. With a denier of 1.0 dpf and a fiber length of only 0.125", the total number of fibers available increases to 4.75 x 10 , adding significantly to the fibers added to the concrete for reinforcement purposes.

Addition of fibers to concrete according to the method of the present invention is simply a matter of introducing the desired number of packages 10 for the volume of concrete directly into the mixing apparatus, without pre-opening of the packages. The concrete is then mixed in a standard fashion which provides the mechanical agitation to tear, shred and destroy the package which permits 3- dimensional isotropic mixing of both the plurality of fibers 20, in the package 10 as well as the second plurality of fibers 25 from the disintegrated package. The fibers 25 depicted in Fig. 1 which comprise the container 12 can be either of the continuous or the discontinuous type, the fibers 25 have been shown schematically, without attempt to depict either type specifically.

Although the package 10 has been described as a container for reinforcing fibers 20, it should be apparent that the package has other utilities. In general, the package can be employed for the addition of other admixture components for cementitious materials such as those described in U.S. Pat. Nos. 5, 120,367 and 5,203,629, the subject matter of which is incorporated herein by reference. More broadly, the package can be employed wherever the addition of fibers 25 from the disintegration of the container 12 is desired or at least would not be detrimental to the material into which the package is placed. The amount of reinforcing fibers typically added to concrete and concrete mixtures is at the rate of about 0.025 to about one percent by volume which, depending upon density of the fiber material, represents about 0.375 pounds to 15 pounds (0.17 to 6.8 Kg) for polypropylene, per cubic yard of concrete, with 0.1 volume percent, or 1.5 pounds (0.68 Kg) per cubic yard being preferred. However, practice of the present invention is not limited to a particular amount of fibers, as the contractor can readily add fibers in the disintegratable packages to the concrete according to the requirements of the given job. Similarly, the other admixture components can be added at the rate specified for their proper functioning; practice of the present invention not being limited by such amounts. Based upon the foregoing disclosure, it should now be apparent that the present invention carries out the objects set forth hereinabove. it should be apparent to those skilled in the art that a wide variety of fiber types can be employed to fill the package. Although the invention has been described in terms of various fibers for the manufacture of the package, it is to be understood that such disclosure should not be construed as any limitation on the scope of the invention, as other types of fibers can be substituted for construction of a suitable container. Similarly, the type of fabric formed for the container and the configuration thereof are all deemed to be within the skill of the art. Finally, the selection of fibers for reinforcing the cementitious material, including graded fibers and, the amounts thereof added can all be determined from the disclosure provided herein. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific fabrics to form the container, the fiber reinforcements and admixture materials, as well as various uses of the package, per se, can be determined without departing from the spirit of the invention herein disclosed and described. Moreover, the scope of the invention shall Include all modifications and variations that may fall within the scope of the attached claims.

Claims

What is claimed is:CLAIMS

1. A package providing reinforcing fibers for a cementitious material comprising: a first plurality of reinforcing fibers; and a non-paper container therefor manufactured from a fabric formed from a second plurality of fibers, said fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing said first plurality of discrete reinforcing fibers and providing said second plurality of reinforcing fibers to the cementitious materials.

2. A package, as in claim 1, wherein said first and second plurality of reinforcing fibers are selected from the group consisting of polyolefins; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides and aromatic polyamides; polyacrylics; fiberglass; carbon fibers, steel fibers, manmade cellulosic fibers and mixtures and blends thereof.

3. A package, as in claim 2, wherein said reinforcing fibers comprise polypropyl- ene.

4. A package, as in claim 1 , wherein said reinforcing fibers are provided In a range of sizes.

5. A package, as in claim 1, wherein said reinforcing fibers are fibrillated.

6. A package, as in claim 1, wherein said second plurality of reinforcing fibers are discrete.

7. A package, as in claim 1, wherein said second plurality of reinforcing fibers are continuous strand fibers.

8. A fiber-reinforced concrete mixture comprising: a preselected amount of cementitious material and at least one package providing reinforcing fibers mixed therewith, said package comprising a first plurality of reinforcing fibers; and a non-paper container therefor manufactured from a fabric formed from a second plurality of reinforcing fibers, said fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material Is mixed, releasing said first plurality of discrete reinforcing fibers and providing said second plurality of reinforcing fibers to the cementi- tious materials.

9. A fiber-reinforced concrete mixture, as in claim 8, wherein said first and second plurality of reinforcing fibers are selected from the group consisting of polyolefins; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides and aromatic polyamides; polyacrylics; fiberglass; carbon fibers and steel fibers and mixtures thereof.

10. A fiber-reinforced concrete mixture, as in claim 9, wherein said reinforcing fibers comprise polypropylene.

1 1. A fiber-reinforced concrete mixture, as in claim 8, wherein said reinforcing fibers are provided in a range of sizes.

12. A fiber-reinforced concrete mixture, as In claim 8, wherein said reinforcing fibers are fibrillated.

13. A fiber-reinforced concrete mixture, as in claim 8, wherein said reinforcing fibers are added to said concrete in an amount of from about 0.025 to one percent by volume.

14. A package for admixtures added to cementitious materials comprising: a non-paper container therefor manufactured from a fabric formed from a plurality of fibers, said fabric having the ability to disintegrate during agitation within apparatus in which the cementitious material is mixed, releasing the admixture and providing said plurality of reinforcing fibers to the cementitious materials.

15. A package, as in claim 14, wherein said plurality of reinforcing fibers forming said fabric are selected from the group consisting of polyolefins; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides and aromatic polyamides; polyacrylics; fiberglass; carbon fibers, steel fibers, manmade cellulosic fibers and mixtures and blends thereof.

16. A package, as in claim 15, wherein said reinforcing fibers comprise polypropylene.

17. A package, as in claim 14, wherein said reinforcing fibers are provided in a range of sizes.

18. A package, as in claim 14, wherein said reinforcing fibers are discrete.

19. A package, as in claim 14, wherein said reinforcing fibers are continuous strand fibers.

20. A method for the addition of a plurality of fibers to cementitious materials which comprises the steps of: introducing at least one package providing a first plurality of reinforcing fibers and a non-paper container, manufactured from a fabric formed from a second plurality of reinforced fibers, to a quantity of cementitious material; and mixing the cementitious material in apparatus with sufficient agitation to shred said container, releasing said first plurality of reinforcing fibers and providing said second plurality of reinforcing fibers to the cementitious material.

21. A method, as in claim 20, wherein said first and second plurality of reinforcing fibers are selected from the group consisting of polyolefins; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides and aromatic polyamides; polyacrylics; fiberglass; carbon fibers, steel fibers, manmade cellulosic fibers and mixtures and blends thereof.

22. A method, as in claim 21, wherein said reinforcing fibers comprise polypropylene.

23. A method, as in claim 20, wherein said reinforcing fibers are provided in a range of sizes.

24. A method, as in claim 20, wherein said reinforcing fibers are fibrillated.

25. A method, as in claim 20, wherein said reinforcing fibers are added to said concrete in an amount of from about 0.025 to one percent by volume.

26. A method for the addition of an admixture to cementitious materials which comprises the steps of: introducing at least one package providing the admixture and a non-paper container, manufactured from a fabric formed from a plurality of reinforced fibers, to a quantity of cementitious material; and mixing the cementitious material in apparatus with sufficient agitation to shred said container, releasing the admixture and providing said plurality of reinforcing fibers to the cementitious material.

27. A method, as in claim 26, wherein said reinforcing fibers are selected from the group consisting of polyolefins; polyesters; polyvinyl chloride; polyvinylidene chloride; polyamides and aromatic polyamides; polyacrylics; fiberglass; carbon fibers, steel fibers, manmade cellulosic fibers and mixtures and blends thereof.

28. A method, as in claim 27, wherein said reinforcing fibers comprise polypropylene.

29. A method, as in claim 26, wherein said reinforcing fibers are provided in a range of sizes.

30. A method, as in claim 26, wherein said reinforcing fibers are discrete.

31. A method, as in claim 26, wherein said reinforcing fibers are continuous strand fibers.