IL170387A

Fiber reinforcement material, products made therefrom and method for making the same

Abstract

This record has no abstract on file.

IL170387A, drawing sheet 1 — Sheet 1 of 55

Term

No projected expiry on record.

88 claims: 17 independent, 71 dependent

1
CLAIMS:1. A fiber reinforcement material, comprising: a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament, twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).
12
A reinforcement for cementitious material, comprising:a plurality of polyolefin monofilaments of about 350 to about 6000 denier per filament, the plurality of monofilaments being in a twisted configuration, the degree of twist being greater than about 0.9 turns/inch (about 0.36 tums/cm).
17
A reinforcement for cementitious material, comprising:a plurality of polyolefin monofilaments, the plurality of monofilaments being in a twisted configuration, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the cementitious material is asphalt.
18
A reinforced cementitious material, comprising:a cementitious mass;and, a fiber component dispersed throughout the mass, the fiber component being a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).
27
A reinforced cementitious material, comprising:a cementitious mass;and, a fiber component dispersed throughout the mass, the fiber component being a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament 01620327\20-01 twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the cementitious mass is asphalt.
28
A reinforcement material for a cementitious material formed by twisting a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament into a fiber bundle for mixing into a cementitious mass, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).
33
A reinforcement material for a cementitious material formed by twisting a plurality of polyolefinic strands of monofilaments into a fiber bundle for mixing into a cementitious mass, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the cementitious mass is asphalt.
34
A reinforced cementitious material, comprising:a synthetic fiber blend distributed through a matrix of the cementitious material, the synthetic fiber blend, including: a first fiber component formed of a homopolymer polypropylene fiber;and a second fiber component being discrete from the first fiber component and being a copolymer formed of a polypropylene and a high density polyethylene, the second fiber component being a 01620327\20-01 plurality of monofilaments twisted to form a non-interconnected bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm),
45
A fiber reinforcement material, comprising:a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament, twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of strands of monofilaments are twisted to form a noninterconnected bundle in the absence of a wetting agent.
46
A fiber reinforcement material, comprising:a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament, twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of strands of monofilaments form a first fiber component, the fiber reinforcement material further comprising a second fiber component that is discrete from the first fiber component and is fibrillated and formed of a homopolymer material.
53
A reinforcement for cementitious material, comprising:a plurality of polyolefin monofilaments, the plurality of monofilaments being in a twisted configuration, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of monofilaments are twisted to form a non-interconnected bundle in the absence of a wetting agent.
54
A reinforcement for cementitious material, comprising:a plurality of polyolefin monofilaments, the plurality of monofilaments being in a twisted configuration, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of monofilaments form a first fiber component, the reinforcement for cementitious material further comprising a second fiber component that is discrete from the first fiber component and is fibrillated and formed of a homopolymer material.
62
A reinforced cementitious material, comprising:a cementitious mass;and, a fiber component dispersed throughout the mass, the fiber component being a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch 01620327\20-01 (about 0.36 tums/cm), wherein the plurality of strands of monofilaments are twisted to form a non-interconnected bundle in the absence of a wetting agent.
63
A reinforced cementitious material, comprising:a cementitious mass;and, a fiber component dispersed throughout the mass, the fiber component being a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of strands of monofilaments form a first fiber component, the reinforced cementitious material further comprising a second fiber component that is discrete from the first fiber component and is fibrillated and formed of a homopolymer material.
73
A reinforcement material for a cementitious material formed by twisting a plurality of polyolefinic strands of monofilaments into a fiber bundle for mixing into a cementitious mass, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of strands of monofilaments are twisted to form a noninterconnected bundle in the absence of a wetting agent.
74
A reinforcement material for a cementitious material formed by twisting a plurality of polyolefinic strands of monofilaments into a fiber bundle for mixing into a cementitious mass, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm), wherein the plurality of strands of monofilaments form a first fiber component, the reinforcement material further comprising a second fiber component that is discrete from the first fiber component and is fibrillated and formed of a homopolymer material.
85
A fiber reinforcement material, comprising:a plurality of polyolefinic strands of monofilaments of about 350 to about .6000 denier per filament, twisted to form a fiber bundle in the absence of a wetting agent.

Independent claims17

455 paragraphs in 18 sections, as filed

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a reinforcement material and, more particularly, to a synthetic fiber material for providing both structural and crack-controlling reinforcement to building materials.

Description of the Background of the Invention

It is well known that the addition of a reinforcement component to building materials such as cementitious materials, brick, asphalt, and the like improves the structural integrity of the material and reduces the likelihood of cracking. When incorporated into cementitious materials such as concrete, for example, the reinforcement component is added to reduce the effect of two main structural deficiencies: 1) low tensile strength; and 2) low strain at fracture. The tensile strength of concrete is relatively low because concrete, when formed, normally contains numerous micro-cracks. It is the rapid

PI-1028152 vl 0200020-0020 matrix, the cut fibers are dispersed through the mixture, open to form webs nets, and thereby improve the strength and binding characteristics of the cementitious matrix.

Some advances have been made in the area of fiber reinforcement to provide increased toughness and durability, and reduce cracking in the matrix of building materials, such as concrete. However, the prior art reinforced fibers have a number of disadvantages that weaken or, otherwise, limit their effectiveness. Accordingly, there is a need for an improved reinforcement fiber that imparts improved structural properties to the building materials to which they are added. In particular, the need exists for a synthetic reinforcement fiber that when added to, for example, cementitious materials, provides a building material that exhibits reduced permeability, increased fatigue strength, improved toughness, and reduced plastic shrinkage.

SUMMARY OF THE INVENTION

In one embodiment, the present invention provides a fiber reinforcement material that includes a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament, twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (0.36 tums/cm).

Tn another embodiment, the present invention provides a reinforcement for cementitious material that includes a plurality of polyolefin monofilaments, the plurality of monofilaments being in a twisted configuration, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).

The present invention also provides a reinforced cementitious material that includes a cementitious mass and a fiber component dispersed throughout the mass. The fiber component is a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament, twisted to form a fiber bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).

PCI7US2003/040385

Tn another embodiment, the present invention provides a synthetic fiber blend for use as reinforcement for cementitious material that includes a first fiber component and a second fiber component The first fiber component is fibrillated and formed of a homopolymer polypropylene fiber. The second fiber component is discrete from the first fiber component is a copolymer formed of a major amount of a polypropylene and a minor amount of a high density polyethylene, and includes a plurality of monofilaments twisted to form a non-interconnected bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm). The first fiber component is present in the synthetic fiber blend in amounts ranging from about 5 to about 50 by total weight percent while the second fiber component is present in the synthetic fiber blend in.amounts ranging from about 50 to about 95 by total weight percent

Tn another embodiment the present invention provides a reinforced cementitious material, comprising a synthetic fiber blend distributed through a matrix of the cementitious material, the synthetic fiber blend including a first fiber component and a second fiber component The first fiber component is formed of a homopolymer polypropylene fiber. The second fiber component is discrete from the first fiber component is a copolymer fonned of a polypropylene and a high density polyethylene, and includes a plurality of monofilaments twisted to form a noninterconnected bundle, the degree of twist being greater than about 0.9 tums/inch (about 0.36 tums/cm).

The present invention also provides a method of forming a reinforcement for cementitious material. The method includes twisting a plurality of polyolefinic strands of monofilaments of about 350 to about 6000 denier per filament into a fiber bundle for mixing into a cementitious mass to form the cementitious material, the twisting occurring to a degree that is greater than about 0.9 tums/inch (about 0.36 tums/cm).

In another embodiment, the present invention provides a method of forming a reinforced cementitous material. The method includes adding to a cementitious mass a plurality of

FIG. 2 illustrates a comparison between the length to width ratios of cracks in slabs containing different amounts of the synthetic fiber blend of the present invention based on percent by volume;

FIG. 3 illustrates a comparison between the time of the appearance of the first crack in slabs containing different amounts of the synthetic fiber blend of the present invention based on percent by volume;

FIG. 4 illustrates a comparison between crack areas between control slabs and slabs containing different amounts of the synthetic fiber blend of the present invention based on percent by volume;

FIG. 5 illustrates a comparison between crack area as a percentage of control in slabs containing different amounts of the synthetic fiber blend of the present invention based on percent by volume;

FIG. 6 illustrates a comparison of crack area reduction in slabs containing different amounts of the synthetic fiber blend of the present invention based on percent by volume;

FIG. 7 illustrates a comparison between the first crack strength in slabs containing different amounts of the synthetic fiber blends of the present invention based on percent by volume;

FIG. 8 illustrates a comparison between the modulus of rupture in slabs containing different amounts of the synthetic fiber blends of the present invention based on percent by volume;

FIG. 9 illustrates a comparison between the first crack toughness in slabs containing different amounts of the synthetic fiber blends of the present invention based on percent by volume;

FIG. 10 illustrates toughness indices versus fiber content in concrete slabs having different amounts of the synthetic fiber blends of the present invention based on percent by volume;

FIG. 11 illustrates Japanese toughness indices versus fiber content in concrete slabs having different amounts of the synthetic fiber blends of the present invention based on percent by volume;

FIG. 24 illustrates a stress - deflection diagram comparing flexural stress versus deflection ofthe synthetic fiber blends of the present invention at 1.9% by volume;

FIG. 25 illustrates a stress - deflection diagram comparing flexural stress versus deflection ofthe synthetic fiber blends of the present invention at 1.9% by volume;

FIG. 26 illustrates a stress - deflection diagram comparing flexural stress versus deflection ofthe synthetic fiber blends of the present invention at 1.9% by volume;

FIG. 27 illustrates a load deflection plot comparing load versus central deflection of the gynthpitir. fiber blends of the present invention in a shotcrete panel at 1.0% by volume;

FIG. 28 illustrates a load deflection plot comparing load versus central deflection of the synthetic fiber blends of the present invention in a shotcrete panel at 1.5% by volume;

FIG. 29 illustrates a load deflection plot comparing load versus central deflection of the synthetic fiber blends ofthe present invention in a shotcrete panel at 1.9% by volume;

FIG. 30 illustrates an embodiment of the present invention wherein the second fiber component is twisted at a particular degree of twisted, identified as X; and

FIG. 31 illustrates a problem in the prior art, wherein the individual strands of monofilament have some splitting and “paint brush” effect

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention. Those of ordinary skill in the art will recognize that associated elements and other items may be employed in the implementation of the present invention. However, because many such associated elements and items are well known in the art, they will not be discussed herein.

In the present detailed description of the invention, the invention will be illustrated in the form of a synthetic fiber reinforcement material for incorporation into a cementitious material. It will be understood, however, that the invention is not limited to embodiment in such form and may be reinforced cement, the resultant cracks of fiber reinforced concrete of the present invention are smaller in width, the permeability of the material is reduced, and the ultimate cracking strain is enhanced.

Furthermore, the blended fibers of the present invention are capable of carrying a load across the crack. In addition, as will be discussed below, tests of the fiber reinforced concrete of the present invention indicate that the concrete material has improved toughness or residual load carrying ability after the first crack, and may have substantially improved impact resistance.

The present invention is directed to a hybrid blend of high performance synthetic fibers and, more particularly, to a blend of synthetic fibers to reduce the effects of plastic shrinkage and improve hardened concrete properties. As will be discussed in greater detail below, it has been discovered that the combination of a first component fiber and a second component fiber to form the hybrid fiber blend of the present invention achieves surprising reinforcement properties and a variety of performance benefits greater than that of which each fiber component is individually capable. In particular, the fiber of the present invention improves control of plastic and settlement shrinkage cracking while improving impact strength, concrete toughness and other structural and long-term durability properties.

The first fiber component is a homopolymer polypropylene fibrous reinforcement material. The first fiber component is a collated, fibrillated, (network) fiber that may be approximately 100 to about 20,000 denier per filament For example, in one embodiment of the present invention the first fiber component is approximately 10,000 denier per filament and includes the following physical properties:

preferably a copolymer formed of major amounts, preferably about 75*80 percent by weight, polypropylene, preferably a low melt polypropylene (2-melt homopolymer), and minor amounts, preferably about 2025־ percent by weight, high-density polyethylene. The second fibers do not fibrillate; i.e., they do not pull apart to form a net like structure in the cementitious material.

The second fiber component is a high tenacity, polyolefinic thread having high resistance, and excellent flexibility. As incorporated in the hybrid blend of the present invention, the second fiber component includes monofilaments of approximately 350 to about 6000 denier per filament. The preferred embodiment of the second fiber component is preferably twisted to form a noninterconnected bundle of multiple strands of a nonfibrillating monofilament In one embodiment of the present invention, the second fiber component exhibits the following properties:

<td colspan="4"> PHYSICAL PROPERTIES OF THE SECOND FIBER COMPONENT</td>

<td> Material</td><td> Virgin Copolymer</td><td> Color</td><td> Gray</td>

<td> Form</td><td> Collated Hybrid- Twisted Monofilaments</td><td> Acid/AIkali Resistance</td><td> Excellent</td>

<td> Specific Gravity</td><td> 0.91</td><td> Absorption</td><td> Nil</td>

<td> Tensile Strength</td><td> 70-106 ksi. (485-730 Mpa)</td><td> Compliance</td><td> A.S.T.M. C-1116</td>

<td> Length</td><td> 2%(54mm)</td><td></td><td></td>

For example, in one embodiment of the present invention, the second component is approximately 750 denier per filament When used alone (not as a hybrid blend in combination with the first component, discussed above, and disclosed herein), the second component is typically added at a dosage rate of about 4 to about 30 pounds per cubic yard (1.8 to 13.6 kilograms per cubic meter) of cementitious material directly to file mixing system during, or after, the batching of the other ingredients and distributed therethrough. The resultant fiber reinforced material exhibits long term durability. It should be noted, however, that the second fiber component, by itself) when not twisted, exhibits less than optimum distribution properties in the building material during mixing operation. However, when the monofilaments of the second fiber component are twisted, as used in the preferred embodiment of the synthetic fiber blend of the present invention, to form the non-interconnected bundle, the synthetic fiber blend is easier to mix and is uniformly distributed throughout the cementitious material.

two or more connected monofilaments that are designed to break apart into individual monofilaments as a result of the act of twisting the fiber strands into the twisted bundle.

It was found through experimental testing that a pronounced improvement in mixing and distribution resulted when the second component was formed with a tighter twist above about 11 s tums/foot (about 0.9 tums/inch or about 0.36 tums/cm), These improved results were observed at a degree of twist less than about 2.2 tums/inch (about 0.87 tums/cm), which is approximately the highest degree of twist that an unheated fiber bundle can be twisted without significant “spring back” effect (i.e. the effect wherein a fiber bundle untwists from its twisted form and, possibly, unbundles due to the resilient properties of the polymer). Typically, the improved properties in mixing and distribution as a result of the degree of twist in the fiber bundle were measured at greater than about 11 tums/foot (about

0.9 tums/inch or about 0.36 tums/cm), and typically occurred in the range between greater than about tums/foot (about 0.9 tums/inch or about 0.36 tums/cm) and about 13 tums/foot (about 1.1 tums/inch or about 0.43 tums/cm), and may occur at a degree of twist of about 13 tums/foot (about 1.1 tums/inch or about 0.43 tums/cm). Moreover, it was found that with an increase in the degree of twist to greater than about 1 tums/inch (about 0.39 tums/cm), little or no splitting or “paint brush” effect was observed in the monofilaments, and nearly all the individual monofilaments that formed the fiber bundle completely separated from the bundle and were disbursed throughout the building material in which it was added. This was particularly evident in certain embodiments of the present invention that employ strands of filament, each strand comprising two ore more connected monofilaments that are designed to break apart into individual monofilaments as a result of the act of twisting the fiber strands into the twisted bundle, ultimately fanning the twisted bundle of monofilaments.

It is contemplated that some additional advantages may be obtained in the mixing and distribution of the second fiber component when the twisted fiber bundle configuration of the second fiber component is heated to below its melting point and twisted, which may allow the fiber bundle to be twisted to a degree of twist that is greater than about 2.2 tums/inch (about 0.87 turns/cm), Tn this embodiment, the individual monofilaments of the second fiber component may be heated, before or

PCT7US2003/040385

<td colspan="4"> PHYSICAL PROPERTIES OF THE FIBER BLEND</td>

<td> Material</td><td> Virgin Polypropylene/Virgin Copolymer</td><td> Color</td><td> Gray</td>

<td> Form</td><td> Collated Hybrid- Fibrillated/ Twisted Monofilament Bundle Fiber System</td><td> Acid/Alkali Resistance</td><td> Excellent</td>

<td> Specific Gravity</td><td> 0.91</td><td> Absorption</td><td> Nil</td>

<td> Tensile Strength</td><td> 90-110 ksi. (620758־ Mpa)</td><td> Compliance</td><td> A.S.T.M. C-1116</td>

<td> Length</td><td> (19mm). Γ/Γ (38mm), 2%54) ״mm), 216 (60mm)</td><td></td><td></td>

When incorporated into a building material such as concrete, the hybrid fiber blend of the present invention may be added to the mixture in amounts ranging from about 0.1 percent to about 2.0 percent by volume of concrete, and typically in amounts ranging from about 0.5 to about 2.0 percent by volume of concrete, to impart improved reinforcement characteristics thereto. The hybrid fiber blend may be added directly to the mixing system during, or after, the batching of the other ingredients and mixed at the time and speed recommended by the mixer manufacturer (typically four to five minutes).

The hybrid fiber blend of the present invention may be used to reduce plastic and hardened concrete shrinkage and settlement shrinkage prior to initial set that leads to cracking. Furthermore, the hybrid fiber blend improves impact strength, and increases fatigue resistance and concrete toughness as an alternate secondaiy/temperature/structural reinforcement. Moreover, in addition to the twisting of the second fiber component, it has been found that the combination of the first fiber component with the second fiber component substantially increases the ability of the second fiber component to be more evenly distributed throughout the mixture. It is believed that the improved distribution properties of the second fiber component, in part, account for the increase in improved reinforcement properties exhibited by the synthetic fiber blend of the present invention. In addition, the fiber of the present invention is non-corrosive, non-magnetic, and substantially resistant to the effects of the alkaline nature of conventional building materials, such as, for example, Portland cement concrete.

PCI7US2003/040385

EXAMPLES Example 1

The hybrid synthetic fibers of the present invention were tested to determine plastic shrinkage reduction of concrete using cement-rich mixes, known to exhibit a high potential for shrinkage cracking. The dosages of fiber used were 0.5,1.0 and 2.0 percent by volume of concrete. Three different batches of concrete were made and a total of 15 slabs were tested. The tests were conducted using a 2.0 inch (5.08 cm) thick slab that was 3 feet (91.4 cm) long and 2 feet (61 cm) wide. The crack development was enhanced by using fans that can produce a wind velocity of 14 mph (22.5 km/hr). The performance of these fibers was compared using the crack areas of control slab with no fibers and fiber reinforced slabs.

As illustrated below, the results of the tests indicate that the fibers of the present invention, at the dosages used, significantly reduced the plastic shrinkage in concrete. The crack area reduction varied from 100 to 92 percent of the plain concrete. No cracking was observed when a fiber dosage of 2.0 percent by volume of concrete was used. There was 98 percent and 92 percent reduction of plastic shrinkage cracking when the fiber dosages were respectively 1.0 percent and 0.5 percent by volume of concrete.

Test

Tests were conducted using 2 inch (5.08 cm) thick slabs that were 3 feet (91.4 cm) long and 2 feet (61 cm) wide. The slabs were restrained around the perimeter using wire meshes. After casting, the slabs were placed on a flat surface and subjected to a wind velocity of 14 mph (22.5 km/hr), using high-velocity fans.

The development ofcracks were observed within two to three and one half hours after casting. Although, typically, cracking is complete within about six to eight hours, the crack widths and lengths were measured after 24 hrs. The longer duration was chosen to ensure all cracks developed and stabilized. The crack width was measured at a number of locations along the length of the crack. The

Mixing Procedure and Casting the Specimens

All mixing was done in a nine cubic feet capacity mixer. The fibers were weighed and stored in a separate container. First the buffer mix was prepared. Thereafter, coarse aggregates were introduced into the mixer. Sand and two thirds of the water were then added and mixed for one minute. Cement was then added along with the remaining one third of the water. Thereafter, the fibers of the present invention were added and the ingredients were mixed for three minutes. Following mixing, the mixture was subject to a three minute rest period, followed by a final mixing stage for 2 minutes for proper fiber distribution.

Because the fiber reinforced cementitious mixes were of a flowing consistency, both mixing and placing were carried out without any problems. No segregation or balling of the fibers was observed in any of the mixes. In order to maintain consistency in placing, consolidating, and finishing the slabs, an experienced concrete contractor and finisher performed the placing, consolidating and finishing for all the slabs.

Three batches were made on three separate days. After each batch of reinforced cementitious material was prepared, the mixing drum was thoroughly cleaned. A buffer mix was prepared before preparing a subsequent mix. All of the mixes were prepared under identical conditions. Test Results and Discussion

Three cylinders were prepared for each of the six mixes with and without fibers according to the ASTM procedures. The cylinders were tested after 14 days of curing. The results are provided in Table 1, below. As illustrated in Table 1, the cylinder strengths in all the mixes were consistently close. The 14-day compressive strength results of all 18 specimens were approximately the same.

The measured crack lengths, widths, and areas for the control and fiber reinforced slabs are given in Tables Al to A3, Bl and B2, and Cl to C2 respectively for batches A, B, and C. Each table compares the mixes prepared on a particular day. The influences of various fiber dosages on the plastic shrinkage cracking are shown in illustrated in Figures 1 to 6. The summary of the test results

TABLEI

14-Day Compression Strength for Shrinkage Test Specimens

<td> Batch No.</td><td> Fiber Content (% by Vol.)</td><td> Specimen No.</td><td> Comp. Strength psi (k״/cm2)</td><td> Average psi (kg/cm*)</td>

<td> A</td><td> 0 (control)</td><td> FEP1-1 FEP1-2 FEP1-3</td><td> 4725.97 (332.27) 4793.98 (337.98) 4701.19 (330.53)</td><td> 4740.38 (338.28)</td>

<td> B</td><td> 0 (control)</td><td> FEP2-1 FEP2-2 FEP2-3</td><td> 4754.36 (334.27) 4833.59 (339.84) 4827.31 (339.39) .</td><td> 4805.09 (337.83)</td>

<td> C</td><td> 0 (control)</td><td> FEP3-1 FEP3-2 FEP3-3</td><td> 4793.97 (337.05) 4361.62 (306.65) 4765.68 (335.06)</td><td> 4640.42 (326.25)</td>

TABLE 3.

Comparison off Various Parameters for Different Fiber Contents

<td rowspan="2"> Slabs with Fiber</td><td rowspan="2"> Lab Batch</td><td rowspan="2"> Fiber Content (% by Vol.)</td><td rowspan="2"> Crack Area (mm2)</td><td rowspan="2"> Crack Length (mm)</td><td rowspan="2"> Crack Width (mm)</td><td rowspan="2"> L/W</td><td rowspan="2"> Time of First Crack (min)</td><td> SIS till</td>

<td> Hnmidi (%)</td>

<td></td><td> Batch C</td><td> 0.5</td><td> 15.09</td><td> 47.10</td><td> 1.02</td><td> 46.176</td><td> 170</td><td> 38</td>

<td></td><td> Batch A</td><td> 1.0</td><td> 6.73</td><td> 52.73</td><td> 1.37</td><td> 38.489</td><td> 195</td><td> 15</td>

<td></td><td> Batch B</td><td> 2.0</td><td></td><td></td><td></td><td></td><td></td><td> 39</td>

<td rowspan="2"> Control Slabs</td><td rowspan="2"> Lab Batch</td><td rowspan="2"> Crack Area (mm2)</td><td rowspan="2"> Crack Length (mm)</td><td rowspan="2"> Crack Width (mm)</td><td rowspan="2"> L/W</td><td rowspan="2"> Time of First Crack (min)</td><td> Casting</td><td> Conditi</td>

<td> Humidity (%)</td><td> Temper! (Peg-</td>

<td></td><td> Batch C</td><td> 192.77</td><td> 238.8</td><td> 5.35</td><td> 44.67</td><td> 120</td><td> 38</td><td> 75</td>

<td></td><td> Batch A</td><td> 304.85</td><td> 431.3</td><td> 9.99</td><td> 43.19</td><td> 125</td><td> 20</td><td> 99</td>

<td></td><td> Batch B</td><td> 399.39</td><td> 317.8</td><td> 9.13</td><td> 34.82</td><td> 120</td><td> 35</td><td> 87</td>

Notes: 1. The values under Crack area, Crack length and Crack width for the slabs with fiber from three slabs.

2. The values under Crack area, Crack length and Crack width for the control slabs t from two slabs.

3. All the three slabs in Batch B did not crack.

Table A2. Details of Crack Lengths, Widths & Areas; Batch A; Control Slab 2.

<td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Avg. Width (mm)</td><td> Area (mm1)</td><td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Avg. Width (mm)</td><td> Area (mm1)</td><td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Avg. Width (mm)</td><td> Area (mm1)</td><td> Crack No.</td><td> Length (mm)</td><td></td>

Table Bl־ Details of Crack Lengths, Widths & Areas; Batch B; Control Slab 1.

<td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Average Width (mm)</td><td> Area (mm1)</td>

<td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Average Width (mm)</td><td> Area (nun2)</td>

Total Area 373.81 |

Table Cl. Details of Crack Lengths, Widths & Areas; Batch C; Control Slab 1.

<td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Average Width (mm)</td><td> Area (mm2)</td>

<td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Average Width (mm)</td><td> Area (mm2)</td>

<td> Total Area</td><td> 210.47</td>

TABLE C3. Details of Crack Lengths, Widths & Areas; Batch C; Slabs Reinforced with Hyb (0.5%)

<td colspan="5"> Slabl ____________1</td><td></td><td colspan="4"> Slab!</td><td></td>

<td> 1 Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Avg. Width (mm)</td><td> Area (mirf)</td><td></td><td> Crack No.</td><td> Length (mm)</td><td> Width (mm)</td><td> Arg. Width (mm)</td><td> Area (nun1)</td>

<td> 5</td><td> 430</td><td> 0.20 030 030 030 030</td><td> 034</td><td> 1.03</td><td colspan="2"></td><td></td><td></td><td> Total Area</td><td> 13.59</td>

[ Total Area [ 26,42]

Slab 3

<td> Crack No.</td><td> Length (mm)</td><td> Width (nun)</td><td> Avg. Width (nun)</td>

Total Area

PCT7US2003/040385 ash and silica fume) the silica fume enhances adhesion and cohesion of the mix and reduces rebound; the fly ash increases paste volume which improves pumpability and shootability.

In order to maintain tight control over mixture proportions, the base shotcrete mix was drybatched. Bone-dry materials were used and all the ingredients were precision mass 5 batched with monitoring. The materials were premixed in a rotary pan mixer with counter rotating paddles, before being discharged into 30 kg paper bags. Shotcrete was supplied on pallets and protected by shrink-wrap and covered under tarps for moisture protection prior to use.

Shotcrete was batched in a modified Allentown Powercrete Pro mixer unit, attached 1□ to a 75 mm swing valve pump. Typically fourteen, 30 kg bags were batched at a time. Water was added to maintain a constant water/cement ratio between all mixes The fibers were added directly to the mixer unit during the mixing cycle and mixed for approximately 5 minutes to provide uniform fiber distribution prior to shotcrete discharge.

The following mixtures were produced: 1) Mixture F10 (nominally 1.0% by volume 15 fiber content); 2) Mixture F15 (nominally 1.5% by volume fiber content); and 3) Mixture F20 (nominally 2.0% by volume fiber content, increased paste volume).

The superplasticizer dosage was adjusted as necessary to provide the required slump for shooting. Mix F20 received a supplementary dose of fly ash and water to increase the paste volume in order to maintain good pumping properties in spite of the high fiber addition 20 rate. Actual admixture dosages for the three mixtures are shown in Technical Reports No. la to lc, below.

pressure. The shotcrete pump used in this testing program had a maximum operating pressure of approximately 16 MPa. The mixture with nominally 2.0% by volume fiber type F20 could be pumped generally satisfactory after the addition of file fly ash and water described above. Mix F20, however, approached the limit of pumpability with the existing equipment and modified base mixture. Several blockages of the shotcrete hoses occurred due to pressure-induced paste starvation near the 50 mm to 38 mm reducer piece with mix F20.

All fibers dispersed well in the shotcrete. No balling was observed. The shotcrete mixes adhered well to the substrates to which they were applied and did not slough.

3. Rebound Testing

Rebound testing was conducted on all mixes in a 2.5 m cube timber framed box, lined with form-ply, open on one vertical face. Shotcrete was applied on a vertical free at the back of the box to an area about 600 x 600 square x 100 mm deep, with four shooting nails demarcating the shooting area. Material which fell to the floor of the rebound chamber was recovered and weighed as rebound. The in-place material was then removed and weighed. Fiber wash-out testing was conducted on the entire rebound sample and on a representative sample of similar mass, taken from the in-place material. The following parameters were calculated: 1) as batched fiber content in kg/m3, percent by volume and percent by mass; 2) in-place fiber content in kg/m3, percent by volume and percent by mass; 3) fiber in rebound in kg/m3, percent by volume and percent by mass; 4) fiber rebound (= mass of all rebounded fibers / mass of all batched fibers x 100%); and 5) fiber retention (= in-place fiber content / as-batched fiber content x 100%).

WO 200S/016644

2. Australian Round Panel Test

One Australian Round Panel was shot for each mixture. The panels had a diameter of 800 mm and were approximately 80 mm thick After shooting, the panel surface was struck off with a wooden two-by-four and finished to a smooth finish with a steel trowel. The panels were moist cured under plastic sheeting in the field for 4 days, then moved into the fog room and stored at 23 +/- 2°C and 100% Relative Humidity until the time of testing.

3. South African Water Bed Test

One test panel with dimensions of 1600 x 1600 x 80 nun thick was shot for each mixture.

Void formers were placed at 1000 mm apart, i.e. at the locations where rock bolts would penetrate to restrain the panel from free vertical movement during the test on the water bed station. The panel ־was shot in a vertical orientation and finished to an equivalent to castconcrete surface finish, using a two-by-four for strike-off and steel trowel finishing.

After initial set, the shotcrete panels were covered with plastic sheets and kept moist and is protected for 7 days. The panels were stripped from the forms at age 21 days and allowed to field cure for a further 8 days prior to testing at age 28 days.

Hardened Shotcrete Properties

1. ASTM Standard Tests

a. Compressive Strength

Six, 75 mm diameter by about 110 mm long cores were extracted from each of the standard

ASTM test panels and tested for compressive strength to CSA A23.2-14C (which is equivalent to ASTM C42). Test results are given in Technical Reports No. 4, below. All force shotcrete mixtures achieved approximately 48 MPa compressive strength at 7 days. The following table shows the ratio of achieved vs. predicted (based on foe mixture

PCT7US2003/040385 calculated from these indices. Also shown are the Japanese Toughness Parameters and

Toughness Performance Levels3.

The results show that there was some instability in the load versus deflection response at deformations up to about 0.5 mm. This is primarily attributed to operation of the test machine in the open loop mode. The following table summarizes the flexural strength and toughness properties of the three mixtures tested.

<td> Mixture</td><td> Fiber Type and As-Batched Volumetric Addition Rate</td><td> Average Flexural Strength [MPa]</td><td> Ratio Flexural vs. Compressive Strength at 7 Days</td><td> Japanese Toughness Factor [MPa]</td><td> Toughness Performance Level</td>

<td> F10</td><td> 2nd generation, 1.0%</td><td> 6.8</td><td> 14%</td><td> 1.7</td><td> in</td>

<td> F15</td><td> 2nd generation, 1.5%</td><td> 6.1</td><td> 13%</td><td> 2.4</td><td> m</td>

<td> F20*</td><td> 2nd generation, 1.9%</td><td> 6.1</td><td> 13%</td><td> 4.0</td><td> IV</td>

<td> F2**</td><td> 1st generation, 2.0%</td><td> 6.5</td><td> 12% (at 8 days)</td><td> 4.1</td><td> IV.</td>

* This mixture was produced with an increased fly ash content ** Mix F2 was previously produced and tested at AGRA, see our Report VA04526

The flexural strengths of the mixtures exceeded the frequently specified minimum of 4 MPa for shotcrete construction projects in Western Canada. The Japanese Toughness Factors and Toughness Performance Levels for shotcrete show a good correlation between fiber dosage and ductility. The fibers performed at a relatively high level and developed good bond with the cement matrix. The fibers also developed most of their load-carrying capacity as indicated by numerous ruptured fibers in the fractured faces.

3 Morgan, D.R, Chen, L., and Beaupre, D., Toughness of Fiber reinforced Shotcrete, ASCE

The test results further showed that when compared to the Synthetic Industries S-152HPP fiber, the hybrid synthetic fibers of the present invention provide superior performance at

1.0% volume addition rate.

3. South African Water Bed Test

The 1600 x 1600 x 76 mm panels were tested on AGRA’s water bed reaction frame, adapted from the South African Water Bed Test developed by Kirsten*. The test set-up comprises a reinforced concrete pedestal with a steel confined reinforced rubber water bed, high tensile strength reaction bolts, and 100 x 100 x 10 mm rock bolt plates. The reaction bolts, which simulate rock bolts, were located on a 1000 mm square grid. The four cantilevered edges of the panels were supported against downward movement by four square hollow section steel profiles positioned by pairs of hydraulic jacks.

The center point deflection of the panels was measured by means of a retracting extensometer mounted on an aluminum bridge and attached to an epoxy glued hook at the center of the panel. A pressure transducer continuously monitored the water pressure in the is water bed, which is correlated to the load applied to the shotcrete test panel. A computer continuously recorded the load and deflection signals. The data were then analyzed and used to plot the load versus deflection curves. The electronically monitored data were verified by mechanical measurements of deflection (measuring tape) and water pressure (analog pressure gauge). Application of load to a total deformation of 150 mm took a total of about

40 minutes.

* Kirsten, H.A.D., System Ductility of Long Fiber Reinforced Shotcrete, Report prepared for Shotcrete Working Group, South Africa, June 1997, pp. 27 and appendices.

PCI7US2003/040385 toughness and system ductility that appears to be equivalent to some high quality steel fiber or welded wire mesh reinforced shotcretes, especially at larger crack widths, hi addition, the shotcrete with 1.9% by volume hybrid fiber provides toughness and system ductility that appears to perform equivalent or better than some high quality steel fiber and welded wire mesh reinforced shotcretes, especially at larger crack widths. TECHNICAL REPORT No.

SUBJECT: Base Wet-Mix Shotcrete Mixture Proportions, SSD Condition

<td> Material</td><td> Mass [kg]</td><td> Bulk Density [kg/m3]</td><td> Volume |m ]</td>

<td> Cement Type 10</td><td> 400</td><td> 3150</td><td> 0.1270</td>

<td> Silica Fume</td><td> 45</td><td> 2200</td><td> 0.0205</td>

<td> Coarse Aggregate (10 - 2.5 mm), SSD</td><td> 500</td><td> 2650</td><td> 0.1887</td>

<td> Water (estimate)</td><td> 180</td><td> 1000</td><td> 0.1800</td>

<td> Water Reducing Admixture: Mastefbuilder® Pozzqlith® 325-N</td><td> 1.40</td><td> 1000</td><td> 0.0014</td>

<td> Superplasticizer: Masterbuilder® Rheobuild® 3000 [L]*</td><td> 2.00</td><td> 1000</td><td> 0.0020</td>

<td> Air Entraining Admixture: Masterbuilder® Microair®</td><td> 0.40</td><td> 1000</td><td> 0.0004</td>

<td> Air Content as shot</td><td> 4.0%</td><td></td><td> 0.0400</td>

<td> Total</td><td> 2288.4</td><td></td><td> 1-θοοθ</td>

Specified 28 Day Strength = 40 MPa

W/(C+SiF+FA) Ratio = 0.38

Slump (after superplasticizer and fiber addition) = 70±20 mm

TECHNICAL REPORT No. lb

As-Batched Shotcrete Mixture Proportions

SUBJECT:

Batch Identification:

Fl 5 Calculated Fiber Content [% by vol.]: 1.51 %

Batch Size (bags):

water/cementing materials ratio: 0.33

<td> Material</td><td> Base shotcrete mass per batch, bone dry [kg]</td><td> Water, Admixtures, Fibers, Fly ash added, per batch [kg]</td><td> Bulk Density [SSD] [kg/nf]</td><td> Calculated SSD Mass per m3 [kg]</td>

<td> Cement Type 10</td><td> 81</td><td> 0</td><td> 3150</td><td> 412</td>

<td> Silica Fume</td><td> 9</td><td> 0</td><td> 2200</td><td> 46</td>

<td> Coarse Aggregate (10 . 2.5 mm)</td><td> 100</td><td> 0</td><td> 2650</td><td> 514</td>

<td> Water</td><td></td><td> 35.8</td><td> 1000</td><td> 164</td>

<td> Synthetic Fibers, FORTA® 1.5%</td><td></td><td> 2.685</td><td> 910</td><td> 13.7</td>

<td> Water Reducing Admixture (Pozzolith® 325-N) [L]</td><td></td><td> 0.360</td><td></td><td> 1.84</td>

<td> Superplasticizer Rheobuild® 3000 IL]*</td><td></td><td> 0.100</td><td></td><td> 0.51</td>

<td> Air Entraining Admixture (Microair®) [L]</td><td></td><td> 0.090</td><td></td><td> 0.46</td>

<td> Air Content At Pump As Shot</td><td> 8.0% 2.0%</td><td></td><td></td><td> 2.0%</td>

<td> Total</td><td> 420</td><td></td><td></td><td> 2345 |</td>

TECHNICAL REPORT No. 2

SUBJECT:

Site Conditions and Fresh Shotcrete Properties

<td rowspan="2"> Property</td><td rowspan="2"> Unit</td><td colspan="3"> I Mix Identification</td>

<td> As-batched Fiber Content</td><td> % by vol.</td><td> 1.01</td><td> 1.51</td><td> 1.90</td>

<td> Water Reducer Addition Rate</td><td> L/m3</td><td> 1.52</td><td> 1.84</td><td> 1.74*</td>

<td> Superplasticizer Addition Rate</td><td> L/m3</td><td> 1.03</td><td> 0.51</td><td> 0.48*</td>

<td> Air Entraining Agent Addition Rate</td><td> L/m3</td><td> 1 0.46</td><td> 0.46</td><td> 0.44</td>

<td> Ambient Temperature</td><td> °C</td><td>21</td><td> 21</td><td> 22</td>

<td> Ambient Wind Speed (estim.)</td><td> m/s</td><td> 2</td><td> 1</td><td> 2</td>

<td> Precipitation ______ ______</td><td></td><td> 0 ־</td><td> 0</td><td> 0</td>

<td> AS-BATCHED Slump (with Fibers and HRWR)</td><td> mm</td><td> 50</td><td> 30</td><td> 50</td>

<td> Air Content (with Fibers and HRWR)</td><td> %</td><td> 8.9</td><td> 8.0</td><td> 8.6</td>

<td> Shotcrete Temperature</td><td> °C</td><td>24</td><td> 26</td><td> 28</td>

<td> AS-SHOT Pumping Pressure (hydraulic circuit)</td><td> MPa</td><td> 11</td><td> 13</td><td> 11</td>

<td> Air Content</td><td> %</td><td> 1.9</td><td> 2**</td><td> 2.6</td>

n.a. =Not Available * mix contains additional fly ash and water for enhanced pumpability ** estimate based on the as-batched air content

TECHNICAL REPORT NO. 3

IS

SUBJECT:

Shotcrete and Fiber Rebound

<td rowspan="2"> Ma No.</td><td rowspan="2"> Mix Description</td><td> 1 Tote! 1 Rebound</td><td colspan="3"> As-batched Fiber Content</td><td colspan="3"> 1 in-place Fiber Content</td><td colspan="3"> Fiber in Rebound 1</td><td> Fiber Retention</td>

<td> F10</td><td> 1.0% Hybrid Fiber</td><td> !12</td><td> 9.1</td><td> 1.0</td><td> 039</td><td> 83</td><td> 0.94</td><td> 037</td><td> 213</td><td> 233</td><td> 0.92</td><td> 94</td>

<td> FI5</td><td> 13% Hybrid Fiber</td><td> 173</td><td> 13.7</td><td> IJ</td><td> 039</td><td> 10.7</td><td> 1.18</td><td> 0.46</td><td> 28.7</td><td> 3.16</td><td> 124</td><td> 78</td>

<td> F20</td><td> 2.0% Hybrid Fiber</td><td> 19.0</td><td> 182</td><td> 2.0</td><td> 0.79</td><td> 14.4</td><td> 138</td><td> 0.62</td><td> 34.7</td><td> 3.82</td><td> 130</td><td> 79</td>

TECHNICAL REPORT No. 6a

SUBJECT: ASTM C1018Toughness Parameters and Residual Strength Factors

Fiber Type: Hybrid Synthetic Fibers

Fiber Addition Rate: 1.0% by vol.

<td rowspan="2"> Sample No.</td><td rowspan="2"> I First-Crack Strength 1 (MPa)</td><td rowspan="2"> Ultimate Strength (MPa)</td><td colspan="3"> Toughness Indices</td><td colspan="2"> Residual Strength Factors</td>

N.A. = not available due to large initial deformations after first-crack

TECHNICAL REPORT No. 6b

SUBJECT: Japanese Toughness Parameters and Toughness Performance Levels

Fiber Type: Hybrid Synthetic Fibers

Fiber Addition Rate: 1.0% by vol.

<td rowspan="2"> 1 Sample No.</td><td rowspan="2"> II First-Crack Strength 1 (MPa)</td><td rowspan="2"> Ultimate Strength (MPa)</td><td colspan="2"> Japanese Toughness Parameters</td><td rowspan="2"> Toughness Ί Performance _______ Levels___________1</td>

<td> Toughness (kN-mm)</td><td> Toughness Factor (MPa)</td>

TECHNICAL REPORT No. 6e

SUBJECT: ASTM C1018 Toughness Parameters and Residual Strength Factors

Fiber Type:

Fiber Addition Rate:

Hybrid Synthetic Fibers 1.9% by vol.

<td rowspan="2"> Sample No.</td><td rowspan="2"> 1 First-Crack Strength 1 (MPa)</td><td rowspan="2"> Ultimate Strength (MPa)</td><td colspan="3"> Toughness Indices</td><td colspan="2"> Residual Strength 1 Factors 1</td>

N.A. = not available due to large initial deformations after first-crack

TECHNICAL REPORT No. 6f

SUBJECT: Japanese Toughness Parameters and Toughness Performance Levels

Fiber Type:

Fiber Addition Rate:

Hybrid Synthetic Fibers 1.9% by vol.

<td rowspan="2"> Sample No.</td><td rowspan="2"> First-Crack Strength (MPa)</td><td rowspan="2"> Ultimate Strength (MPa)</td><td colspan="2"> Japanese Toughness Parameters</td><td rowspan="2"> Toughness Performance Levels</td>

<td> Toughness (kN’mm)</td><td> Toughness Factor (MPa)</td>

A total of four mixes, one for each fiber content were made. The basic mixture proportions were the same for all four concrete mixtures, except for two mixes with 1.5 and 2.0 percent by fiber volume, the workability was increased by increasing water cement ratio. The fiber reinforced concrete mixtures were mixed, placed, consolidated, finished and cured under identical conditions. The test results indicate that there was no balling or segregation due to the addition of fibers at the recommended dosages for all four mixes.

Test results show that there was a significant increase in the flexural strength and a slight increase in the first crack strength as the fiber content was increased from 0.5 to 2.0 percent by volume. The ASTM toughness indexes and the Japanese toughness factors and equivalent flexural strengths were also significantly increased as the fiber content increased. There was also a significant increase in impact strength for an increase in fiber content.

Test results further show that very high average residual strengths (AIRS) (ASTM C1399) were obtained and the ARS values increased as the fiber content increased. The ARS values were 234 psi (16.45 kg/cm2), 451 psi (31.71 kg/cm2), 454 psi (31.92 kg/cm2), and 654 psi (45.98 kg/cm2) for fiber contents of 0.5,1.0,1.5,2.0 percent by volume, respectively.

Overall, the performance of reinforced concrete incorporating file fibers of the present invention were similar and/or better than the concretes reinforced with the best steel fibers available in the market compared on an equal weight or cost basis. The following pFirformance. related tests were performed to determine the physical characteristic of the fibers of the present invention: 1) the properties of fresh concretes with different dosages of fibers; 2) the properties of hardened concretes such as compressive strength, static modulus, static flexure strength, and unit weight; 3) the toughness indices by the ASTM method with the help of load deflection curves; 4) comparisons in tbe load deflection curves for the four fiber reinforced concretes; 5) comparisons in the toughness factor and equivalent flexural coarse aggregates were introduced into the mixer. Thereafter, sand and two thirds of the water were added and mixed for one minute. Cement was then added along with the remaining one third of the water. The fibers of the present invention were added and the ingredients were mixed for three minutes. Following a three minute rest period, the mixture underwent a final mixing stage for 2 minutes to completely distribute the fibers.

Test Specimens

The following specimens were cast from each mix: 1) four 101 x 101 x 356 mm (4in x 4in x 14in) beams for ASTM toughness test; 2) four 101 x 101 x 356 mm (4in x 4in x 14 in) beams for ARS Test (ASTM C 1399); 3) three 152 x 304 mm (6 in x 12 in) cylinders for compressive strength and static modulus; and 4) ten 152 x 63 mm (6 in x 2.5 in.) cylinders for impact test The specimens were cast according to the ASTM standards and covered with plastic sheets for 24 hours at room temperature. The specimens were then placed in a lime saturated water tank maintained at 22.22°C (72° F), and remained in water till they were is tested for 14-day strengths.

Tests for Fresh Concrete

Freshly mixed concrete was tested for slump (ASTM C143), air content (ASTM C231), fresh concrete unit weight (ASTM C 138), and concrete temperature. No balling or segregation

0 was observed due to the addition of fibers.

Tests for Hardened Concrete

1. Static Modulus and Compressive Strength

3. Load Deflection Behavior

The area under the curve represents the energy absorbed by the beam. Load deflection curves for both the pre first crack and post first crack data, were drawn. Toughness indices and the residual strength indices’ were calculated by using these curves.

4. Flexural Toughness (Energy Absorption)

Toughness, or energy absorption, of concrete is increased considerably by the addition of fibers. Toughness index is the measure of the amount of energy required to deflect the 100 mm (4 in) beam in the modulus of rupture test. The most important variable governing the toughness index of fiber reinforced concrete is the fiber efficiency. Other parameters influencing the toughness index are the position of the crack, the fiber type, aspect ratio, volume fraction and the distribution of fibers. Fiber efficiency is controlled by the resistance of the fiber to pull out from the matrix, which is developed as a result of the bond strength at the fiber matrix interface. The advantage of pullout type of failure of fiber is that, it is gradual and ductile, compared to a more rapid and catastrophic failure, which may occur, if fibers are brittle and foil in tension with little or no elongation. The fiber pullout or fracture depends on the yield strength of the fibers, the bond and anchorage between the matrix and the fiber.

Toughness index (ASTM CIO 18) is a dimensionless parameter, which defines or finger prints the shape of the load deflection curve. Indices have been defined on the basis of three service levels, identified as the multiples of the first crack deflection. The index is computed by dividing the total area under the load deflection curve up to the first crack deflection. The toughness index 15 is calculated at three times the first crack deflection. Likewise 110,120 and 130 are the indices up to 5.5,10.5 and 15.5 times the first crack deflection respectively.

adjusted to lightly contact the beam sample in accordance with the chosen method for obtaining net deflection so that readings were immediately obtained upon beam reloading.

The deflection-recording device was again brought to zero and reloaded at the specified rate.

The test was terminated at a deflection of 1.25 mm (0.50 in) as measured from the beginning of reloading.

Using the Excel package file graphs were drawn and die residual strengths were calculated by the formulas given below.

Test Apparatus and Set-Up

The test apparatus satisfied the ASTM standards. A specially designed frame was used to mount the dial gauge with 0.0025-mm (0.0001-in.) resolution. This frame was supported only at the four points, which are on the neutral axis above the supports. The dial gauge was fixed such that it was touching the center point of the bottom surface. This arrangement enabled the measurement of the true deflection excluding any extraneous deformations due to crushing of concrete at supports and load points and any deformations and strains induced in the testing frame. Because the deflection is measured at the center point, any slight warping or twisting of beam will not affect true deflections measured. In addition to the dial gage, LVDT was also mounted and the deflections were recorded by a data acquisition system. These readings were used for verification of dial gage readings.

Calculations

The average residual strength for loads at reloading deflections of 0.50, 0.75,1.00, and 1.25 mm (0.02,0.03,0.04, and 0.05 in) are calculated using the following formula:

1. Fresh Concrete Properties

Room temperature, humidity and concrete temperature were recorded to ensure that all the mixes were earned out under similar conditions. The room temperature and humidity varied in the range of 65°F to 85°F and 35% to 45% respectively. The concrete temperature varied from 65 to 73 F (18.3-22.8°C). The unit weights of higher dosage fiber concrete were slightly less than the concretes with lower fiber dosages. The fresh concrete properties are given in Table 5.

2. Workability

The test results indicate that satisfactory workability can be maintained even with the addition of the fibers. Hie concrete started to harden in about 40 to 45 minutes. The fibers mixed well and were uniformly distributed throughout the concrete. Overall, there was no bridging, bleeding or segregation. Even though the slump values show the decreasing trend with the addition of the fibers, no difficulty was encountered in placing and consolidating the concrete with the use of the table vibrator.

3. Air Content

The air content ranged from 1.4 to 1.8 %. No air-entraining agent was used. Therefore the measured air is considered as entrapped air.

Hardened Concrete Properties

1. Compressive Strength & Static Modulus Test

The results of the compressive strength test are tabulated in Table 6 and show that there is a variation in the compressive strength. Compressive strength depends on water cement ratio mode of failure from a brittle type to a ductile type is an important contribution due to the addition of fibers.

The static modulus test served primarily as a means of quality control. The results indicate that the mixes were reasonably consistent and the addition of fibers had no effect on the static modulus. The static modulus values are given in Table 6.

2. Static Flexural Strength (Modulus of Rupture)

The static flexural strength test results, the first crack load, ultimate load and flexural stress are given in Table 7. ’When the fiber concrete beams were loaded in flexure, the behavior was approximately linear up to the first crack and then the curve was significantly non-linear and reached its peak at the ultimate strength, or at the maximum sustained load. In contrast, the control (plain) concrete beams would fail immediately at the appearance of the first crack and hence the first crack strength and flexural strength (modulus of rupture) would be the same for control concrete. The factors that significantly influence the flexural strength and the toughness are the fiber type and the fiber volume. The first crack strength variation versus fiber content is shown in Figure 7. As illustrated, there is an increase in the first crack strength as the fiber content increased from 0.5 to 2.0 percent The modulus of rupture (static flexural strength) versus fiber content is shown in Figure 8. As illustrated, there is a significant increase in the flexural strengths for 1.5 and 2.0 percent fiber contents. The average flexural strength for mixes El and E2 were 643 psi (45 kg/cm2) and 658 psi (46 kg/cm2) respectively whereas for mixes E3 and E4, the strengths were 720 psi (51 kg/cm ) and 731 psi (51 kg/cm2)respectively which is a 13.7 percent increase.

5. Impact Strength

The drop weight (ACI Committee 544) impact test results are given in Table 10. The number of blows to first crack and final failure versus the fiber content are shown in Fig. 14. Though a relatively simple test, if more specimens are tested, the mean values indicate qualitatively a good index of the impact resistance of the material. Ten specimens were tested for each concrete and the average values are plotted in Fig. 14. The impact resistance increased considerably with an increase in fiber content. It is well known from previous testing that the plain concrete impact resistance will be about 1/6 to 1/15 of that fiber concrete with 0.25 to 2.0 percent by volume.

6. Average Residual Strength

Four beams were tested for fiber content. The average widths and depths of the beams, file loads obtained upon reloading at deflections of 0.5,0.75,1.0, and 1.25 mm (0.020,0.030, 0.040,0.050 inch), and the average residual strengths (ARS) are given in Table 11. The ' load-deflection curves obtained by reloading and re-testing the pre-cracked beam (without the steel plate) are given in FIGS. 15-26. The calculated ARS values for all four fiber reinforced concretes are shown in Fig. 7. The test results indicate that the average residual strength increased considerably with an increase in fiber content The ARS values were 234 psi (16.5 kg/cm2), 451 psi (31.7 kg/cm2), 454 psi (31.9 kg/cm2), and 654 psi (46.0 kg/cm2) for fiber contents of 0.5,1.0,1.5,2.0 percent by volume, respectively. It can be seen that 180 percent increase in ARS was obtained when the fiber content was increased from 0.5 to 2.0 percent by volume.

Since the ARS values are only due to the influence of fiber, irrespective of the compressive strength of the concrete, the ARS values were not normalized. The mixes El (with 0.5 indicated that the fiber was very effective in sustaining the post crack load. The ARS value increased with increases in fiber content. There was an 180 percent increase in the ARS value when the fiber content was increased from 0.5 to 2.0 percent by volume. This increase took place despite a reduction in compressive strength from 4960 psi (349 kg/cm2) to 3860 psi (271 kg/cm2). Accordingly, the performance of fiber reinforced concrete mixtures of the present invention were similar or superior than the concrete reinforced with the best steel fibers available in the market compared on an equal weight or cost basis.

Table 4

Mix Proportions

<td rowspan="2"> Mix Design.</td><td rowspan="2"> Water Cement Ratio</td><td colspan="2"> Fibers</td><td colspan="3"> Weight in kgflbs)</td><td rowspan="2"> Water kg(lbs)</td>

<td> kg(lbs)</td><td> Vol %</td><td> Cement kg(lbs)</td><td> Coarse Agg. kg(lbs)</td><td> Fine Agg kg(lbs)</td>

Table 6 Cylinder Compressive Strength and Static Modulus

<td> Specimen ID</td><td> Age (Days)</td><td> Diameter in. __(<™)</td><td> Length in. __</td><td> Unit weight Ib/ft3 (kg/m3)</td><td> Static modulus 106 psi (kg/cm2)</td><td> Comp, strength psi (kg/cm2)</td>

<td rowspan="2"> Average</td><td></td><td> (15.243)</td><td> (30.691)</td><td> (2419)</td><td> (0.273)</td><td> (343)</td>

<td> Average</td><td></td><td> (15.240)</td><td> (30.691)</td><td> (2387) 148</td><td> (0.273) 3.86</td><td> (329) 4760</td>

<td> Average</td><td></td><td> (15.156)</td><td> (30.691)</td><td> (2387) 148</td><td> (0.231) 3.68</td><td> (243) 3570</td>

<td> StdDev</td><td></td><td></td><td></td><td> (2371) 1.00</td><td> (0.259) 0.35</td><td> (251) 218</td>

<td> Average</td><td></td><td> (15.171)</td><td> (30.691)</td><td> (2339) 147</td><td> (0.229) 3.25</td><td> (277) 3860</td>

<td colspan="6"> SI Unit Conversion Factors</td><td></td>

linch= 2.54 cm 1 lb = 0.4536 kg psi = 703 kg/m2 Ib/ft3 = 16.02 kg/m3

TABLE 8

ASTM - TOUGHNESS INDICES -14 DAYS

<td rowspan="3"> Mixture Type</td><td rowspan="3"> Specimen #</td><td rowspan="3"> First Crack Toughness inch-lbs (Nm)</td><td colspan="4"> Toughness</td><td colspan="3" rowspan="2"> Toughness Ratios</td><td rowspan="2"></td>

<td></td><td> Average</td><td> 1.0(0.11)</td><td> 3.97</td><td> 7.37</td><td> 13.05</td><td> 17.79</td><td> 1.9</td><td> 1.8</td><td> 1.4</td><td></td>

<td></td><td> Average</td><td> 1.0(0.11)</td><td> 3.5</td><td> 6.2</td><td> 10.8</td><td> 14.8</td><td> 1.8</td><td> 1.7</td><td> 1.4</td><td></td>

<td></td><td> Average</td><td> 1.1 (0.12)</td><td> 4.0</td><td> 7.6</td><td> 14.7</td><td> 21.6</td><td> 1.9</td><td> 1.9</td><td> 1.5</td><td></td>

<td></td><td> Average</td><td> 1.5(0.17)</td><td> 4.0</td><td> 7.6</td><td> 14.3</td><td> 20.8</td><td> 1.9</td><td> 1.9</td><td> 1.5</td><td></td>

Conversion Factor: lin-lb = 0.113Nm

PCI7US2003/040385

TABLE 10

IMPACT TEST RESULTS -14 DAYS

<td rowspan="2"> Mixture Type</td><td rowspan="2"> Age (Days)</td><td rowspan="2"> Specimen #</td><td colspan="2"> Number of Blows to</td><td rowspan="2"> Difference in no. of blows from first crack to failure</td>

<td> First Crack</td><td> Failure</td>

<td></td><td></td><td> Average</td><td> 84</td><td> 193</td><td> 109</td>

<td></td><td></td><td> Average</td><td> 99</td><td> 404</td><td> 305</td>

<td></td><td></td><td> Average</td><td> 94</td><td> 351</td><td> 257</td>

<td></td><td></td><td> Average</td><td> 216</td><td> 464 1</td><td> 248</td>

As set forth above, it is contemplated that embodiments of the fiber composition of the present invention provide improved properties to various types of cementitious material, including asphaltbased material. For example, embodiments of the present invention were employed in test strips of asphalt roadways in amounts of about 2.0 to about 3.3 pounds per ton along with an oil emulsion and aggregate (3/8” (1 cm) limestone chip) and monitored for surface failures and damage resulting from typical environmental wear and use. The test strips were full width (edge of pavement to edge of pavement). Cold-mix asphalt roadways that did not employ the fiber compositions of the present invention had experienced surface failure, such as unraveling on hills, curves, and shaded areas of recently paved roads. Surface failures were due to longitudinal and transverse separation attributed to heave axle loads, such as, truck and farming equipment traffic. Road maintenance vehicles, such as snow plows, and their method of snow removal accentuated the surface failures. Test results indicated that areas of the asphalt roadway that did employ the fiber composition of the present invention showed little or no longitudinal or transverse separation relative to areas of the roadway that did not employ asphalt material reinforced with the fiber compositions of die present invention. It is believed that embodiments of the present invention may increase the life span of roadways from two to three years to up to ten years in cold-mix asphalt.

The foregoing examples demonstrate that the hybrid fibers of the present invention when used in building material, such as cementitious material, perform as well or better than many or all prior art reinforcement fibers, including steel reinforcement fibers. Further, the foregoing experiments demonstrate that relatively small concentrations of fiber will support substantially improved results. These observations are both surprising and unexpected.

31 members in 11 offices

This recordMember, by publication datePriority claim1 more office is in the list below

Priority claims8

Priority claims
Document	Office	Kind	Date
63302603	United States of America	A	2003-08-01
63302603	United States of America	A	2003-08-01
0340385	United States of America	W	2003-12-18
0340385	United States of America	W	2003-12-18
10633026	–	–	–
PCTUS2003040385	–	–	–
US20030633026	–	–	–
WO2003US40385	–	–	–

Members31

Family members, oldest first
Document	Office	Kind
CA2517276A1	Canada	A1	2004-02-24
US2004038027A1	United States of America	A1	2004-02-26
US6753081B1	United States of America	B1	2004-06-22
WO2005016644A1	World Intellectual Property Organization (WIPO)	A1	2005-02-24
AU2003297334A1	Australia	A1	2005-03-07
MXPA05010880A	Mexico	A	2006-03-21
EP1648700A1	European Patent Office (EPO)	A1	2006-04-26
CN1802254A	China	A	2006-07-12
HK1085695A1	Hong Kong, China	A1	2006-09-01
US7168232B2	United States of America	B2	2007-01-30
CN100431832C	China	C	2008-11-12
CN101428982A	China	A	2009-05-13
IL170387AThis record	Israel	A	2010-02-17
AU2003297334B2	Australia	B2	2010-03-11
EP2168931A2	European Patent Office (EPO)	A2	2010-03-31
EP1648700A4	European Patent Office (EPO)	A4	2010-05-26
ES2344398T1	Spain	T1	2010-08-26
EP2168931A3	European Patent Office (EPO)	A3	2010-09-22
HK1141268A	Hong Kong, China	A	2010-11-05
HK1141268A1	Hong Kong, China	A1	2010-11-05
CA2517276C	Canada	C	2012-07-17
EP1648700B1	European Patent Office (EPO)	B1	2013-05-22
EP2168931B1	European Patent Office (EPO)	B1	2013-06-26
PT1648700E	Portugal	E	2013-08-29
CN101428982B	China	B	2013-09-18
PT2168931E	Portugal	E	2013-09-25
EP2650125A1	European Patent Office (EPO)	A1	2013-10-16
ES2425742T3	Spain	T3	2013-10-17
ES2344398T3	Spain	T3	2013-11-07
EP2650125B1	European Patent Office (EPO)	B1	2021-10-20
PT2650125T	Portugal	T	2022-01-24

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2017-11-30	Patent renewedKB	KB
2013-11-28	Patent renewedKB	KB
2010-11-30	Patent grantedGrantedFF	FF
2010-11-30	Patent renewedKB	KB

Fiber reinforcement material, products made therefrom and method for making the same

Abstract

Term

BACKGROUND OF THE INVENTION

SUMMARY OF THE INVENTION

PCI7US2003/040385

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

PCT7US2003/040385

PCI7US2003/040385

TABLEI

WO 200S/016644

SUBJECT:

SUBJECT:

TECHNICAL REPORT NO. 3

IS

SUBJECT:

TABLE 8

ASTM - TOUGHNESS INDICES -14 DAYS

PCI7US2003/040385

TABLE 10

IMPACT TEST RESULTS -14 DAYS

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