IL104317A - Metal fiber mat reinforced composites - Google Patents

Metal fiber mat reinforced composites

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Publication number
IL104317A
IL104317A IL10431793A IL10431793A IL104317A IL 104317 A IL104317 A IL 104317A IL 10431793 A IL10431793 A IL 10431793A IL 10431793 A IL10431793 A IL 10431793A IL 104317 A IL104317 A IL 104317A
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Prior art keywords
fibers
structural member
mat
inch
fiber
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IL10431793A
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IL104317A0 (en
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Ribbon Technology Corp
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Publication of IL104317A0 publication Critical patent/IL104317A0/en
Publication of IL104317A publication Critical patent/IL104317A/en

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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/38Fibrous materials; Whiskers
    • C04B14/48Metal
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04CSTRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/01Reinforcing elements of metal, e.g. with non-structural coatings
    • E04C5/012Discrete reinforcing elements, e.g. fibres
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04CSTRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/01Reinforcing elements of metal, e.g. with non-structural coatings
    • E04C5/02Reinforcing elements of metal, e.g. with non-structural coatings of low bending resistance
    • E04C5/04Mats

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Structural Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Laminated Bodies (AREA)

Description

METAL FIBER MAT REINFORCED COMPOSITES RIBBON TECHNOLOGY CORPORATION C:16217 Docket No. R-1884-002 PATENT METAL FIBER MAT REINFORCED COMPOSITES The present invention relates to a cement itious member reinforced by a non-woven mat of long steel fibers.
U.S. Patent 3,429,094 to Romualdi, U.S. Patents 3,986,885/ 4, 366,255 and 4,513,040 to Lankard, U.S. Patent 4,617,219 to Schupak and U.S. Patent 2,677,955 to Constant inesco disclose metal fiber reinforced cementitious composites.
While these composites have been commercially successful, there are several areas in which improvement would be desirable. The fiber-filling step can be time-consuming and therefore expensive. The quantity of fiber required to develop improved resistance to thermal and mechanical shock is high. In practice, the complete strength of the fiber is not always utilized.
Summary of the Invention In accordance with the present invention, a metal fiber-reinforced structural member or composite is provided wherein the member comprises a non-woven, pre-formed mat of metal fibers which is infiltrated by and encased in a hardened cementitious composition; the mat is characterized in that the fibers are .004 to .060 inches in effective diameter, greater than 3 inches in length and have an aspect ratio (length/diameter) of about 400 to 1000 or they are continuous, and the density of the mat expressed as a percentage of the fiber occupied volume to the total volume of the mat is about 1 to 10%.
The fiber mat-reinforced composite of this invention is advantageous for several reasons. First, for a comparable volume . - - of fibers, the composites of the invention provide higher fLexurai strength. Consequently, for comparable flexural strength, the volume of fibers in the composite can be reduced.
The fiber mat reinforced composites of the invention exhibit higher energy absorption capacity than composites reinforced with discrete fibers, and their energy absorption efficiency (energy absorption capacity per unit volume of fibers) is unexpectedly higher. The superior performance of the mat reinforcement over the discrete fibers is related to the bonding of the mat fibers in the composite. With discrete fibers having relatively short embedment length (e.g., 1 in.) fiber pullout. is the primary failure mode. For example, see U.S. Patent 3,986,885, Col. 5, lines 2-8 and U.S. Patents 3,429,094, Col 4, lines 5-10. Once a crack forms in the member under flexural load, the energy absorption capacity of the specimen reflects the energy required to propagate and enlarge this single crack.
Energy absorption is dictated by fiber pullout resistance.
Composites reinforced with the metal fiber mats in accordance with this invention represent a departure from the prior art. The mode of failure in flexure is distinctly different. Here, multiple cracking occurs in the composites.
Ultimate failure occurs through fiber breakage in high tensile stress zones of one or more of the crack planes. The energy absorption capacity of the mat reinforced composites reflects the total energy required to initiate, enlarge, and propagate all of the cracks and to break a portion of the fibers in one or more of the cracks. In the fiber mat reinforced composites described herein, the yield strength of the steel is more fully utilized. Contrary to what one skilled in the art might have expected based on short fiber reinforced composites, energy absorption is not dictated by fiber pull out resistance. A further advantage of reinforcing concrete composites in accordance with this invention as opposed to using individual fibers is that a known amount of fiber can be placed into the composite at a known cost. oc e o. - - Brief Description of the Drawing Fig. 1 is a photograph of a steel fiber mat useful in accordance with the invention.
Fig. 2 is a perspective view of a reinforced concrete structure in accordance with the present invention.
Fig. 3 is a cross-sectional view of fiber mat reinforced structural member in accordance with the invention.
Fig. 4 is a photograph of a craciced steel fiber reinforced comparative composite.
Fig. 5 is a photograph of a craciced long steel fiber mat composite in accordance with the invention.
Definition The term "non-woven" as used herein with respect to the metal fiber mats means that the fibers forming the mat are not systematically woven. The mat is held together by random entanglement of the fibers.
The term "effective diameter" is used herein as it is used in the art, namely, to mean the diameter of a circle the area of which is equal to the cross -sectional area of the steel fiber .
Detailed Description of the Invention The fibers forming the reinforcing mat used in the present invention are greater than 3 inches long, preferably greater than 6 inches long and still more preferably about 7 to 12 inches long. The fibers have an aspect ratio of about 400 to 1000.
Fiber mats useful in accordance with the invention are commercially available from Ribtec, Ribbon Technology .
Corporation, Gahanna, Ohio under the tradename SIMCON. One such mat is shown in Fig. 1.
Metal fiber mats useful in the present invention can be prepared by the methods and apparatus described in U.S. Patents 4,813,472 and 4,930,565 to Ribbon Technology Corporation. These patents disclose the production of metal filamentary materials ranging from a size less than one inch up to semicon inuous fibers. To prepare metal fiber mats, the aforesaid methods may be used to prepare fibers. The fibers are drawn from the molten metal using a melt overflow or melt extraction technique similar to that described in these patents and related patents. Other methods may be used to prepare long fibers. For example, slit sheet processes and milling processes may be used to prepare long fibers which in turn are air layed and compressed into mats. The fibers are preferably about 7 to 12 inches long and more preferably about 9 inches long. The fibers are blown into a chute where they are air layed on a conveyor and compressed into a mat. By controlling the rate of the conveyor and the extent of compression of the mat, the density of the mat can be controlled to produce mats in the range of 1.5 to 6.0% density.
The optimum fiber length may vary with each particular application and the nature of the fiber, e.g., its diameter, steel composition and the method by which it is manufactured. A length may be selected at which the force required to pull the fiber from the concrete exceeds the force required to form a new crack, in the concrete, i.e., the minimum fiber length should be sufficient to prevent pullout.
Typically, the fibers are steel fibers such as carbon steel, stainless steel or manganese steel. Stainless steel fibers are preferred for refractory applications. The fibers commonly range in effective diameter from about .004 to .060 incr. and more preferably form about .010 to .025 inch. Smaller diameter fibers are shown to provide higher energy absorption capacity in Examples 1 and 2 below. The fibers typically are not circular in cross -section but have thickness and width dimensions. For example in the examples they range from about .02 to .05 in width and from about .005 to .015 inch in thickness. A fiber having a circular cross section is also useful, but noncircular fibers are more commonly available and often less expensive. Depending upon the strength of the fibers, they may be corrugated. However, for smaller diameter wires most commonly used (e.g., .010 or .020 inch) corrugation is generally not desirable under tensile stress, the corrugation tends to be pulled out of the wire. As the corrugation is pulled out of the wire, the wire strength does not reinforce the concrete and the concrete cracks and fails.
The amount of fiber in the mat and the composite may range from about 1 to 10% by volume. In order to incorporate more than about 10% fiber into a composite, the mat must be compressed to an extent that it cannot readily be infiltrated with a cementitious mixture. Typical composites in accordance with the invention are prepared from mats which contain about 2 to 6% by volume fiber.
The fibers may be randomly oriented in the composite or oriented to maximize the strength of the composite in a selected direction. For example, the mat fibers may be oriented parallel to the direction in which the structural member will encounter its principal tensile stress. In many applications, due to the geometry of the structural member, the fibers will assume some degree of orientation. For example, typically, the fibers are about 7 to 12 inches long. In making a panel 2 inches thick, the fibers will be oriented generally perpendicular to the thickness or Z direction of the panel and generally parallel to the X-Y plane of the panel. Within the X-Y planes, the fibers may assume a parallel or a random alignment.
Any cementitious composition which will infiltrate the fiber mat may be used in the present invention including hydraulic and polymer cements. Mortar and concrete compositions oc et o. - - are useful. Representative examples of useful cements include Portland cement, calcium aluminate cement, magnesium phosphate cement, and other inorganic cements. Useful aggregates may range up to about 30 mesh (0.023 inch) so they are not strained from the composition as they impregnate the mat. Examples of aggregates incLude sand and small gravels. Refractory concretes are used in making refractory shapes such as plunging bells, injection lances and ladle lip rings.
A superplastici 2 ing agent may be added to the slurry of the cementitious material to better enable it to infiltrate the fibers and fill the mold. A superplasticizing agent is not required but is preferred. Without the superplasticizer , more water must be added to the slurry to infiltrate the mat.
Superplasticizing agents are known and have been used in flowing concrete and water-reduced, high strength concrete. See for example "Superplast icized Concrete", ACI Journal, May, 1977, pp. N6-N11 and "Flowing Concrete", Concrete Constr., Jan., 1979 ( pp 25-27). The most common superplasticizers are sulfonated melamine formaldehyde and sulfonated naphthalene formaldehyde. The superplasticizers used in the present invention are those which enable the aqueous cementitious slurry to fully infiltrate the packed fibers. Of those plasticizers that are commercially available, Mighty 150, a sulfonated naphthalene formaldehyde available from ICI is preferred.
Composites in accordance with the invention are useful in making a variety of structural members including panels, beams, columns, pavement slabs and refractory shapes. A typical embodiment of a reinforced structure in accordance with the invention is shown in FIG. 2. The embodiment there shown is of a panel 10 provided with a non-woven metal fiber reinforcing mat 12 which is completely embedded in a cementitious composition 13. The face 14 of the panel 10 generally has fibers of the reinforcing layer incorporated therein and clearly visible. In this embodiment, the fibers are randomly oriented. The ends 18 Docket No. R-1884-002 of fibers forming the mat 12 can be seen from the sides 20 and 21 of panel 10.
In one embodiment of the invention, the mat fiber reinforced panel may be incorporated in a sandwich construction where a pair of mac fiber reinforced panels sandwich a layer of a large aggregate concrete or a layer of concrete reinforced by-discrete metal fibers. Such a structural member can be prepared by placing a fiber mat in a form and infiltrating that mat with a concrete slurry containing an aggregate which will not infiltrate the mat, e.g., a stone aggregate greater than 35 mesh. The large aggregate will be "screened" from the slurry and collect on the top surface of the mat. A second mat is placed in the form overlying the first and sandwiching the layer of large aggregate therebetween. This second mat is infiltrated with a cement slurry not containing the larger aggregate resulting in a slab in which the large area surfaces are mat reinforced and the core is larger aggregate concrete. Alternatively, metal fibers of the type referred to in the Romualdi and Lankard patents may be mixed with the concrete in an amount of 1 or 2% and poured between two long fiber mat reinforced concrete layers to form a sandwich construction.
FIG. 3 illustrates, in a cross-sectional view, the sandwich structure 30 described above. This structure comprises two layers 22 and 24 which are formed from a hydraulic cement matrix with or without aggregate fillers and reinforced with non-woven elements 23 and 25 and which are separated from each other by a layer of concrete 26. The thickness of the two reinforced outer layers 22 and 24 can be the same or different and the relative thickness of the two outer layers versus the thickness of the inner mortar or concrete layer can be varied over a wide range depending upon the particular application for which the resulting structure is to be employed. The inner layer of mortar or concrete 26 can be reinforced, if desired, by means such as discrete metal fibers and the like to impart additional Docket No. R-1884-002 structural strength to the sandwich structures of the invention. The particular embodiment illustrated in FIG. 3 has two outer reinforcing layers enclosing a concrete core. However, as will be apparent to one si illed in the art, sandwich structures in accordance with the invention can be provided in which there are a plurality of non-woven mat reinforced layers each cf which is separated form its neighbor by a layer of concrete.
The reinforced structures of the invention can be prepared conveniently in a straightforward manner. In one preparation, the reinforcing member such as that illustrated in FIG. 1 is placed in a tray or mold the internal surface of which optionally may be previously treated with a conventional mold release agent. An appropriate amount of cementitious composition necessary to completely infiltrate and encapsulate the reinforcing member is then deposited on the latter. Means such as vibration, ultrasonic stimulation, and the like, can be employed in order to ensure thorough permeation of the reinforcing member by the cementitious composition. The upper surface of the mix can then be screeded if desired in order to ensure a planar surface of the desired finish. Thereafter, the impregnated reinforcing material is caused to cure by any conventional means.
The invention is illustrated in more detail by the following non-limiting examples.
Example 1 Two 304 stainless steel fiber mats were provided. Mat A is 2 inch thick x 18 inch wide x 38 inch long. The weight of Mat A is 8.2 lb. These dimensions and the weight yield a fiber volume of 2.3 percent. The individual fibers comprising this mat have a length of 8.81 inch, a width of around 0.04 inch, and thickness of about 0.011 inch (average of measurements on 10 fibers randomly selected from the mat).
Doc et No. - - Mat B measures 2-1/2 to 3 inch thick x 20 inch wide x 38-1/2 inch long. The mat weighs 24.2 lb. These dimensions and weight yield a fiber volume percent of 4.5. However, when compressed to a 2 inch thickness, the fiber volume is 5.7 percent. The mats were individually placed in a plywood form for a 2 inch x 20 inch x 40 inch long panel. Mat B is compressed to a final thickness of about 2 inch by the sides of the form. All joints in the form are silicone sealed to contain the infiltrating slurry.
The fiber mats are infiltrated with a fine-grained refractory concrete slurry (Wahl Refractories SIFCA Composition). Approximately 180 lb. of the slurry was used at a water content of 18.5 percent to fill the form.
Following the slurry infiltration step, the slurry was cured for 24 hours at 85 to 90' F. Following this curing period, the panels were removed from the mold and given a further four days cure at 80° F at 100 percent relative humidity in a fog room. Following the fog room curing period, each panel was cut into 4 inch wide beams using a diamond saw. Specimens 2 inch x 4 inch x 20 inch were then oven dried at 230" F prior to testing the flexural strength properties.
For comparison, a composite reinforced by discrete fibers was prepared using 1.0 inch long stainless steel fibers. These specimens were prepared using the procedure described in U.S. Patent No. 4,366/255. The fiber content of the comparison composite is 14 volume percent. The composite specimens were cured and dried in the same manner as the composites prepared using the stainless steel fiber mats.
Flexural strength testing was done on two of the 2 inch x 4 inch x 20 inch beams prepared form the various composites. Testing was done using third-point loading and a 12 inch span. Load-deflection data were recorded during the flexural strength testing. Testing was done in accordance with ASTM C1018, The Standard Test Method For Flexural Toughness and First-Crack Doc et No. - - Strength of Fiber-Reinforced Concrete (using beam with third-point loading). The results are shown in Table 1. Table 1 compares the ultimate flexural strength and a measure of the flexural toughness index for the three composites investigated here. The comparison composite with a fiber loading of 14 volume percent had an ultimate flexural strength of 6440 psi. The composite prepared with Mat B (fiber loading = 5.7 volume percent) had 40 percent of the fiber loading of the conventional composite yet exhibited an ultimate flexural strength 85 percent that of the conventional composite (5470 psi vs. 6440 psi).
Table 1. Flexural Strength Properties of Composites Reinforced with Ty Stainless Steel Fibers in Mat Form and in Discrete 1.0 Inch L (a) Total area measured under the load-deflection curve to a deflection (b) Relative to the composite yielding the highest area under the load- (Mat B) oc e o. - - Load-def Lection data were recorded during the flexural strength testing of the composites. To permit a comparison between the composites evaluated here, a total area under the load-deflection curve to a maximum deflection of 0.35 inch was calculated. These results are also presented in Table 1.
A comparison of the areas under the load-deflection curves between the comparison composite at 14 volume percent fiber and Mat B at 5.7 volume percent fiber establish the superior energy absorbing capacity provided by the long fiber mat mode of reinforcement. The superior performance of the mat reinforcement over the discrete fibers is related to the bonding of the long mat fibers in the composite. In the comparison composite, the relatively short embedded length of the fibers (about 1.0 inch) results in fiber pullout as the primary failure mode. Once a crack forms in a comparison specimen under a flexural load, the energy absorption capacity of the specimen reflects the energy required to propagate and enlarge this single crack. Energy absorption is dictated by fiber pullout resistance. The cracked sample is shown in Fig. 4.
In the composites reinforced with the stainless steel fiber mats, multiple cracking occurs in the specimen subjected to flexural loading. In the specimens containing the mat reinforcement, at least 50 cracks have developed in that portion of the specimens subjected to high tensile stresses. The energy absorption capacity of this composite reflects the energy required to initiate, enlarge, and propagate all of these cracks and to break a portion of the 304 stainless steel fibers.
Ultimate failure in the mat reinforced composite is breaking of fibers in one or more of these crack planes. This cracked sample is shown in Fig. 5. The cracks have been blackened for illustration.
The improvement which the invention provides in energy absorption efficiency as calculated by dividing the energy absorption capacity by the volume percent fiber loading is shown in Table 1A oc e o. - - Table 1A Energy Absorption Efficiency (A) (B) Mat Fiber Load Energy Absorption Eff iciencv % (v/o) Capacity (B)/(A) A 2.3 428 186 B 5.7 1326 232 Comparison 14.0 926 66 Example 2 Four carbon steel (manganese) fiber mats were used in the preparation of panels. The mats measured approximately 40 inch x 20 inch x 2 to 3 inch thick.. The mats are identified as follows: 1% v/o Effective Diameter 0.010 inch MN Steel 2% v/o Effective Diameter 0.013 inch MN Steel 4% v/o Effective Diameter 0.021 inch MN Steel 4% v/o Effective Diameter 0.013 inch MN Steel Ten fibers from each mat were selected at random for characterization. The characterization included measurements of weight, length, width, and thickness. The results of the characterization measurements are presented in Table 2. The fiber loading values differ from the intended values of 1.0, 2.0 and 4.0 volume percent. The reported values above were calculated based on fiber mat weight and dimensions.
Characteri zation Measurements of Hibtec Carbon S (Manganese) Fibers Incorporated Into Fiber "Mats on August 2, 1991 ! i lici We i <|li t , ijin l.engt h , i n. Widt h, in. Th i ck ld. ll 1 f 1 ( ,) 1 ) on R ng Average Range Average Range Average R ng 0.01 2 «> .348 0.021 0.004 M t C Lo 0.1213 to 9.577 to 0.022 t o 0.010 1 ilx i 0.1364 9.603 0.02) 0.007 0.1446 6.491 0.02 ) 0.006 Kit D to 0.204') to 9.265 to 0.025 to 0.2459 9.62'j 0.027 0.010 0.21») 9.506 0.037 0.010 Mil E t 0.3962 to 9.590 to 0.039 to 0.021 l itter 0. 356 9.621 0.042 0.012 0.1446 6.491 0.023 0.006 Kit F to 0.2045 to 9.265 to 0.025 to 0.013 fiber 0.2459 9.625 0.027 0.010 .
The Length of the individual fibers is about 9-1/2 inch. Fiber width varied from 0.022 inch to 0.039 inch with thickness varying from 0.006 inch to 0.011 inch.
Each of fiber mats C-F was enclosed in a 20 inch x 40 inch x 2 inch wooden mold with the open face (filling port) being the 2 inch x 40 inch dimension. A calcium aluminate cement-based slurry (SIFCA Slurry manufactured by Wahl Refracto ies, Fremont, Ohio) was used to infiltrate these panels. Once infiltration was achieved, the panels were cured one day in the mold and then placed in a 74'F/100%RH environment until cwo individual specimens (roughly 2 inch x 4 inch x 20 inch) were sawcut from each panel.
For comparison purposes, three 2 inch x 4 inch x 14 inch beam specimens were also prepared with the comparison composite containing 14 volume percent 1 inch long 304 stainless steel fibers prepared in Example 1. These specimens were also cured az 74" F/100%RH until sawcutting of the panels was complete.
Following the sawcutting step, all of the specimens were oven dried at 230' before flexural strength testing.
The criteria used for evaluating the reinforcement efficiency of these composites was flexural strength and flexural load-deflection behavior. Flexural strength testing was done on two beams for each fiber loading using third-point leading and a 12 inch span. Table 3 compares the ultimate flexural strength and a measure of the flexural toughness for the composites investigated here.
Load-deflection data were recorded during the flexural strength testing of the composites. To permit a comparison between the composites evaluated here, a total area under the load-deflection curve to a maximum deflection of 0.35 inch, was calculated.
The mode of failure of the mat specimens in flexure is through a breaking of the fibers at the point of highest tensile stress in the specimen (bottom surface of the beam specimens in the flexural strength test). The mat composites do not fail Table \ . I) I t im.it e I'lcxiir.il St . reinjt.It .IIKI Knergy A sot pt io f. Miirujiinese Steel Mnt Ho inforced Composit ? Cont 1.2 to 3.6 Volume Percent 1·' i bers Average Fl Fiber Ul t i mate Ultimate Absor Compos i te Spec i men Load ng , Flexur 1 Flexura 1 Type Number v/o Strength, Strenth, Area psi ps i L-D Curv 5a 1.2 1925 MAT C 1950 20 Reinforced 5b 1.2 1970 6a 1.7 3190 MAT D 3205 71 Re i nl orcod 6b 1.7 3225 7a 3.3 4680 MAT E 4805 71 Re i nforced 7b 3.3 4930 8a 3.6 4730 MAT F 4865 109 Reinforced 8b 3.6 5000 la 14.0 6910 Comparison 6440 92 .0 in. Fi ers lb 14.0 59 0 . catastrophically inasmuch as the fibers in zones away from the highest tensile stress zone do not fail at the same strain capacity. Fibers on the compression surface of the beams (top side) remain intact even at extremely nigh deflections.
The mode of failure of the comparison composite with the 1.0 inch fibers is principally fiber pullout.
The average ultimate flexural strength of the comparison composite (14 volume percent 1 inch fibers) is 6440 psi.
Manganese carbon steel Mats E and F at fiber loadings of 3.3 and 3.6 volume percent respectively provided an ultimate flexural strength of 4800 psi in the composite (roughly 75 percent that cf the comparison composite). Manganese steel fiber Mat D at a fiber loading of 1.7 volume percent had an average ultimate flexural strength of 3200 psi or 50 percent that of the comparison composite. Manganese steel Mat C at a fiber loading of 1.2 volume percent had an average ultimate flexural strength of 1950 psi or around 30 percent that of the comparison composite.
The efficiency of the mat concept regarding the achievement of flexural strength in composites is clearly demonstrated by these results. Mat F at a reinforcement level only 25 percent that of the Comparison composite had an ultimate flexural strength 75 percent that of the Comparison. Mat D at a reinforcement level only 12 percent that of the Comparison provided an ultimate flexural strength of 50 percent that of the Comparison.
The reinforcement efficiency of the mat of reinforcement over the standard discrete fiber approach is even more clearly demonstrated by the ability of the mats to enhance energy absorption capacity of these composites and by the significant enhancement in energy absorption efficiency shown in the long fiber mats. Mat F with a fiber loading only 25 percent that of the Comparison had an energy absorption capacity 15 percent greater than the Comparison. Energy absorption efficiency is shown in Table 3A.
Docket No. R-1884-002 Table 3A Energy Absorption Efficiency Ma Fiber Load Energy Absorption Efficiency ( ¾ ) Capac ity C 1.2 204 170 D 1.7 712 419 E 3.3 718 218 F 3.6 1091 303 Comparison 14.0 926 66 A comparison of the energy absorption capacity of the composites reinforced with Mat D and Mat E reveal the important effect of fiber diameter on this property in the mat reinforced composites. Mat D provided a fiber loading roughly half that of Mat E , yet provided an equivalent energy absorption capacity in the composite. The only intended difference in the two mats is a smaller fiber diameter in Mat D (0.013 inch) relative to Mat E (0.021 inch).
The influence of fiber diameter is also seen in the comparison of the energy absorption capacity of the composites prepared with Mat E and Mat F. Here, the fiber loading is roughly equivalent (3.3 and 3.6 volume percent) but the energy absorption capacity in the finer diameter steel Mat F is 35 percent greater than that in the composite containing the coarser fiber Mat E. The ultimate flexural strength of these two mat reinforced composites is equivalent (around 4800 psi).
The reason for the effect of fiber diameter on energy absorption capacity was revealed by an inspection of the beam specimens following flexural strength testing. In the composite containing the larger diameter fiber (Mat E), considerably fewer cracks were formed relative to the specimens containing the fine . fiber (equivalent diameter = 0.013 inch). For example, in the coarse fiber composite (Mat E) the number of cracks formed was around five while in the fine fiber composite (Mat D) over 20 cracks were formed. Additionally, in the composite prepared with Mat F (3.6 volume percent of the 0.013 inch diameter fiber) ultimate failure occurred through a shear plane oriented roughly at a 45 degree angle to the long dimension of the beam. Multiple cracking also occurred around this diagonal crack.
Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
What is claimed is:

Claims (25)

20 104317/2 Claims :
1. A reinforced cementitious structural member comprising a non-woven mat of reinforcing metal fibers infiltrated by and encased in a hardened cementitious composition, said fibers being about .004 to .060 inch in effective diameter, greater than 3 inches long and having an aspect ratio of about 400 to 1000, said mat containing about 1 to 10 % by volume metal fibers.
2. The structural member of claim 1 wherein said metal fibers are randomly oriented.
3. The structural member of claim 1 wherein said metal fibers are oriented substantially parallel to the direction of principal tensile stress in said member.
4. The structural member of claim 1 wherein said cementitious composition contains aggregate having a particle size less than 30 mesh.
5. The structural member of claim 4 wherein said cementitious composition is a hydraulic cement.
6. The structural member of claim 4 wherein said cementitious composition is a polymer cement.
7. The structural member of claim 4 wherein said cementitious composition is a refractory concrete.
8. The structural member of claim 1 wherein said member is a panel .
9. The structural member of claim 8 wherein said panel includes a first face reinforced with said mat, a second face reinforced with a second mat and a core of a large aggregate 21 104317/2 concrete .
10. The structural member of claim 1 wherein said metal fibers are drawn from molten metal by melt overflow or melt extraction .
11. The structural member of claim 10 wherein said metal fibers are stainless steel, carbon steel or manganese steel fibers .
12. The structural member of claim 11 wherein said fibers are greater than 4 inches long.
13. The structural member of claim 12 wherein said fibers are about 6 to 12 inches long.
14. The structural member of claim 13 wherein said fibers are about .005 to .015 inch in effective diameter.
15. The structural member of claim 14 wherein said fibers have an aspect ratio of about 400 to 800.
16. The structural member of claim 11 wherein said fibers are sufficiently long that said fibers are bonded to said cementitious composition such that upon failure of said member under tensile stress, said fibers do not substantially pull out from said member.
17. The structural member of claim 16 wherein said metal fibers are present in said member in an amount of about 2 to 6 percent by volume.
18. The structural member of claim 17 wherein said composite exhibits higher energy absorption efficiency as compared to a composite formed from an equal volume of discrete metal fibers. 22 104317/3
19. The structural member of claim 18 wherein said fibers are continuous .
20. The structural member of claim 15 wherein said fibers have an effective diameter of about .010 to .025 inch.
21. The structural member of claim 20 wherein said mat contains about 2 to 6% by volume metal fibers.
22. A reinforced cementitious structural member comprising a non-woven mat of reinforcing metal fibers infiltrated by and encased in a hardened cementitious composition, said fibers being drawn from molten metal and being about .004 to .060 inch in diameter, greater than 3 inches long and having an aspect ratio of about 400 to 1000 or being continuous, said mat containing about 1 to 10% by volume metal fibers.
23. The structural member of claim 22 wherein said fibers have an effective diameter of about .005 to .015 inch, said fibers are greater that 4 inches long.
24. The structural member of claim 23 wherein said fibers are discontinuous fibers and have an aspect ratio of 400 to 800.
25. The structural member of claim 24 wherein said fibers have an effective diameter of about .010 to .025 inch, said fibers are about 6 to 12 inches long, and said mat contains about 2 to 6% by volume metal fibers. C: 16217
IL10431793A 1992-03-16 1993-01-06 Metal fiber mat reinforced composites IL104317A (en)

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IL104317A true IL104317A (en) 1995-10-31

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US5308572A (en) * 1992-11-17 1994-05-03 Ribbon Technology Corporation Method for manufacturing a reinforced cementitious structural member
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JPH08502014A (en) 1996-03-05

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