Cementitious compositions having highly dispersible polymeric reinforcing fibers

• US 20030082378A1
• Filed: 12/11/2002
• Published: 05/01/2003
• Est. Priority Date: 04/25/2001
• Status: Active Grant

• Current Assignee: GCP Applied Technologies Inc. (Compagnie De Saint-Gobain)
• Original Assignee: W.R. Grace & Co.-Conn. (WR Grace & Company)
• Inventors: Berke, Neal S., Ranganathan, Anandakumar, Rieder, Klaus-Alexander, Macklin, Michael B.
• Granted Patent: US 6,758,897 B2
• Time in Patent Office: Days
• US Class Current: 428/373
• CPC Class Codes: C04B 16/06 fibrous
• CPC Class Codes: C08J 5/04 Reinforcing macromolecular compounds with loose or coherent fibrous material
• CPC Class Codes: D01D 5/253 with a non-circular cross section; Spinnerette packs therefor D01D5/38 takes precedence
• CPC Class Codes: E04C 5/073 Discrete reinforcing elements, e.g. fibres
• CPC Class Codes: Y10T 428/249932 Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 428/24994 Fiber embedded in or on the surface of a polymeric matrix
• CPC Class Codes: Y10T 428/2904 Staple length fiber
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2922 Nonlinear [e.g., crimped, coiled, etc.]
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/2964 Artificial fiber or filament
• CPC Class Codes: Y10T 428/2967 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/2973 Particular cross section
• CPC Class Codes: Y10T 428/2978 Surface characteristic

Abstract

Synthetic polymer reinforcing fibers provide dispersability and strength in matrix materials such as concrete, masonry, shotcrete, and asphalt. The individual fiber bodies, substantially free of stress fractures and substantially non-fibrillatable, have generally quadrilateral cross-sectional profiles along their elongated lengths.

Claims

1. Fibers for reinforcing matrix materials, comprising:

a plurality of individual fiber bodies having an elongated length defined between two opposing ends and comprising at least one synthetic polymer,

said individual fiber bodies being substantially free of stress fractures and substantially non-fibrillatable when mechanically agitated within the matrix material to be reinforced,

said fiber bodies having a generally quadrilateral cross-sectional profile along said elongated length, thereby having width, thickness, and length dimensions,

wherein the average width is at least 1.0 mm;

wherein the average width is no more than 5.0 mm;

wherein the average thickness is at least 0.1 mm;

wherein the average thickness is no more than 0.3 mm;

wherein the average length is at least 20 mm; and

wherein the average length is no more than 100 mm.

2. The fibers of claim 1 wherein said average width is no less than 1.3 mm;

said average width is no greater than 2.5 mm;

said average thickness is no less than 0.15 mm;

said average thickness is no greater than 0.25 mm;

said average length is no less than 30 mm; and

said average length is no greater than 60 mm.

3. The fibers of claim 1 wherein, in said plurality of individual fiber bodies, said individual fiber bodies are separated from each other.

4. The fibers of claim 1 wherein, in said plurality of individual fiber bodies, said individual fiber bodies are partially separated from each other but are completely separable when mechanically agitated within the matrix material.

5. The fibers of claim 1 wherein, in said plurality of individual fiber bodies, said at least one synthetic polymer is selected from the group consisting of polyethylene, polypropylene, polyoxymethylene, poly(vinylidine fluoride), poly(methyl pentene), poly(ethylene-chlorotrifluoroethylene), poly(vinyl fluoride), poly(ethylene oxide), poly(ethylene terephthalate), poly(butylene terephthalate), polyamide, polybutene, and thermotropic liquid crystal polymers.

6. The fibers of claim 1 wherein said fiber bodies comprise polypropylene in an amount no less than 75% by weight and said fiber bodies comprise polypropylene in an amount up to 100%.

7. The fibers of claim 6 wherein said fiber bodies comprise a blend of at least two polymers or a co-polymer comprising at least two of said polymers.

8. The fibers of claim 7 wherein said fiber bodies comprise polypropylene and polyethylene.

9. The fibers of claim 1 wherein said fiber bodies have a Young'"'"'s modulus of elasticity of no less than 3 Giga Pascals and wherein said fiber bodies have a Young'"'"'s modulus of elasticity no more than 20 Giga Pascals.

10. The fibers of claim 1 wherein said fiber bodies have a tensile strength of no less than 350 Mega Pascals and wherein said fiber bodies have a tensile strength of no more than 1200 Mega Pascals.

11. The fibers of claim 1 wherein said fiber bodies have a minimum load carrying capacity in tension mode of no less than 40 Newtons per fiber body and said fiber bodies have a minimum load carrying capacity in tension mode of no more than 900 Newtons per fiber body.

12. The fibers of claim 1 wherein said fiber bodies have a width to thickness ratio of no less than 4 and wherein said fiber bodies have a width to thickness ratio of no more than 50.

13. The fibers of claim 1 wherein said fiber bodies have a width to thickness ratio of no less than 5 and wherein said fiber bodies have a width to thickness ratio of no more than 20.

14. The fibers of claim 1 wherein said fiber bodies have an average bendability “

B”

of no less than 20 mN<sup>−

1</sup>*m<sup>−

2</sup> and wherein said fiber bodies have an average bendability “

B”

of no more than 1300 mN<sup>−

1</sup>*m<sup>−

2</sup>, said bendability “

B”

of said fibers being determined in accordance with the formula, B=1/(3·

E·

I), wherein the moment of inertia “

I”

for a generally rectangular cross-section is computed in accordance with the formula, I_rectangle=1/12·

w·

t³, wherein “

w”

is the average width and “

t”

is the average thickness of the generally rectangular cross-section.

15. The fibers of claim 1 wherein said fiber bodies have an average bendability “

B”

of no less than 25 mN<sup>−

1</sup>*m<sup>−

2</sup> and wherein said fiber bodies have an average bendability “

B”

of no more than 500 mN<sup>−

1</sup>*m<sup>−

2</sup>, said bendability “

B”

of said fibers being determined in accordance with the formula, B=1/(3·

E·

I), wherein the moment of inertia “

I”

for a generally rectangular cross-section is computed in accordance with the formula, I_rectangle=1/12·

w·

t³, wherein “

w”

is the average width and “

t”

is the average thickness of the generally rectangular cross-section.

16. The fibers of claim 1 wherein said fiber bodies have an average surface square area “

S_A”

to volume “

V”

ratio of no less than 7.0 and wherein said fiber bodies have an average S_A to V ratio of no more than 22.1.

17. The fibers of claim 16 wherein said fiber bodies have an average surface square area “

S_A”

to volume “

V”

ratio of no less than 10 and wherein said fiber bodies have an average S_A to V ratio of no more than 15.

18. The fibers of claim 1 further comprising a second plurality of individual fiber bodies, wherein said second plurality differs in terms of fiber composition, dimensions, a physical characteristic, or combination thereof.

19. The fibers of claim 1 being coated, bundled, packaged, packeted, coated, adhered, or contained together.

20. The fibers of claim 19 wherein said individual fiber bodies are partially connected together as a scored sheet which is operative to separate into said individual fiber bodies when said sheet is introduced into, and mechanically agitated, in a hydratable cementitious composition.

21. The fibers of claim 1, wherein said matrix materials are hydratable cementitious compositions.

23. A matrix composition comprising said fibers of claim 1 and a matrix material selected from the group consisting of adhesives, asphalt, composite materials, plastics, elastomers, and hydratable cementitious materials.

24. The matrix composition of claim 23 wherein said matrix material is a hydratable cementitious composition and said fibers comprise polypropylene.

25. The matrix composition of claim 23 wherein said fibers are present in the matrix composition in the amount no less than 0.05% by volume and wherein said fibers are present in the matrix composition in an amount no greater than 10% by volume.

26. Method for modifying a matrix material, comprising introducing into a matrix material the fibers of claim 1.

32. The fibers of claim 1 wherein said individual fiber bodies have a variability of thickness or width along the individual fiber body length of no less than 2.5 percent deviation from average thickness or width as the case may be, and wherein said individual fiber bodies have a variability of thickness or width along the individual fiber body length of no greater than 25 percent deviation from the average thickness or width as the case may be.

33. The fibers of claim 1 wherein said individual fiber bodies comprise at least two synthetic polymers, one of said at least two synthetic polymers comprising an alkaline soluble polymer disposed on the outward fiber surface thereby being operative to dissolve when said fiber bodies are mixed into the alkaline environment of a wet concrete mix.

34. The fibers of claim 1 wherein said individual fiber bodies are coated with an alkaline soluble polymer operative to dissolve when said fiber bodies are mixed into the alkaline environment of a wet concrete mix.

35. The fibers of claim 1 wherein said plurality of fibers are contained in packaging with an admixture.

36. The fibers of claim 35 wherein said admixture is selected from the group consisting of a superplastizicer, water reducer, air entrainer, air detrainer, corrosion inhibitor, set accelerator, set retarder, shrinkage reducing admixture, fly ash, silica fume, pigments, or a mixture thereof.

22. Fibers for reinforcing matrix materials, comprising:

a plurality of individual fiber bodies having an elongated length defined between two opposing ends and comprising at least one synthetic polymer, said individual fiber bodies being substantially free of stress fractures and substantially non-fibrillatable when mechanically agitated within the matrix material to be reinforced, said fiber bodies having a generally quadrilateral cross-sectional profile along said elongated length, thereby having width, thickness, and length dimensions

wherein the average width is no less than 1.0 mm;

wherein the average width is no more than 5.0 mm;

wherein the average thickness is no less than 0.1 mm;

wherein the average thickness is no more than 0.3 mm;

wherein the average length is no less than 20 mm;

wherein the average length is no more than 100 mm;

wherein the average fiber width to thickness ratio is no less than 5;

wherein the average fiber width to thickness ratio is no more than 50;

wherein said fiber bodies have a Young'"'"'s modulus of elasticity no less than 3 Giga Pascals;

wherein said fiber bodies have a Young'"'"'s modulus of elasticity no more than 20 Giga Pascals;

wherein said fiber bodies have a tensile strength no less than 350 Mega Pascals;

wherein said fiber bodies have a tensile strength of no more than 1200 Mega Pascals;

wherein said fiber bodies have a minimum load carrying capacity in tension mode no less than 40 Newtons per fiber body;

wherein said fiber bodies have a minimum load carrying capacity in tension mode no greater than 900 Newstons per fiber body;

wherein said fiber bodies have an average square area to volume ratio no less than 7.0;

wherein said fiber bodies have an average square area to volume ratio no more than 22.1;

wherein said fiber bodies have an average bendability “

B”

no less than 25 mN<sup>−

1</sup>*m<sup>−

2</sup>; and

wherein said fiber bodies have an average bendability “

B”

no more than 500 mN<sup>−

1</sup>*m<sup>−

2</sup>.

said bendability “

B”

of said fibers being determined in accordance with the formula, B=1/(3·

E·

I), wherein the moment of inertia “

I”

for a generally rectangular cross-section is computed in accordance with the formula, I_rectangle =1/12·

w·

t³, wherein “

w”

is the average width and “

t”

is the average thickness of the generally rectangular cross-section.

27. Process for manufacturing fibers, comprising:

melt extruding at least one synthetic polymeric material through a sheet dye;

cooling the extruded sheet to below ambient temperature;

cutting the extruded sheet to form separate fibers to achieve a generally quadrilateral cross-sectional provide and resultant average width and thickness dimensions, wherein the average width is at least 1.0 mm, wherein the average width is no more than 5.0 mm, wherein the average thickness is at least 0.1 mm, and wherein the average thickness is no more than 0.3 mm;

stretching said fibers longitudinally by a factor no less than 10 and no greater than 20; and

cutting said fibers to provide average fiber length no less than 20 and no greater than 100 mm.

28. The process of claim 27 wherein said stretching said fiber longitudinally precedes said cutting to provide average fiber lengths of no less than 20 and no greater than 100 mm.

29. The process of claim 27 wherein said cutting to provide average fiber lengths of no less than 20 and no greater than 100 mm precedes said stretching.

30. The process of claim 27 wherein said cooling comprises taking up said melt extruded polymeric material on a chill roll.

31. The process of claim 27 wherein said cooling comprises passing said melt extruded polymeric material through a water bath.