Profiled Structural Concrete Fiber Material And Building Products Including Same, And Methods
A synthetic fiber material made with multipolymer blends which have been fibrillated in oriented film form is provided that is useful as a secondary reinforcement material, which has a low Young's modulus for a more uniform distribution throughout a cementitious mixture incorporating the fiber material, and imparts good finishability, strength, and improved plastic shrinkage crack control, in addition to providing improved conformability within cementitious forms, especially within forms comprising bends equal to or greater than about 45 degrees. Improved cementitious compositions and fiber-reinforced concrete building products incorporating the synthetic fiber materials are also provided, as well as methods for making the synthetic fiber materials.
1 . A synthetic fiber material comprising a multi-polymer blend containing a first polymer comprising polypropylene and a second polymer selected from polyethylene and polystyrene, and wherein the synthetic fiber material having undergone at least 5% fibrillation per square inch.
2 . A synthetic fiber material as in claim 1 , wherein the multi-polymer blend comprises (a) a highly isotactic polypropylene homopolymer, (b) high molecular weight polypropylene homopolymer of substantially lower melt flow rate than (a), and (c) high strength linear polyethylene.
3 . A synthetic fiber material as in claim 1 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 190 psi at 5 lbs. per cubic yard loading at 8 days cure.
4 . A synthetic fiber material as in claim 1 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 140 psi at 4 lbs. per cubic yard loading at 8 days cure.
5 . A synthetic fiber material as in claim 1 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 110 psi at 3 lbs. per cubic yard loading at 8 days cure.
6 . A synthetic fiber material as in claim 1 , wherein said synthetic fiber material exhibits a Young's modulus at 30% elongation of between 5.5 and 9.5 Gpa.
7 . A synthetic fiber material as in claim 1 , wherein said synthetic fiber material has a thickness of between 1.0 and 3.5 mil.
8 . A synthetic fiber material as in claim 1 , wherein the synthetic fiber material comprises a fibrous network have a laced configuration.
9 . A cementitious composition containing a hydratable cementitious material and a synthetic fiber material according to claim 1 .
10 . The cementitious composition of claim 9 , wherein the multi-polymer blend comprises (a) a highly isotactic polypropylene homopolymer, (b) high molecular weight polypropylene homopolymer of substantially lower melt flow rate than (a), and (c) high strength linear polyethylene.
11 . The cementitious composition of claim 9 , wherein the curable cementitious material comprises portland cement.
12 . The cementitious composition of claim 9 , wherein said synthetic fiber material exhibits a Young's modulus at 30% elongation of between 5.5 and 9.5 Gpa.
13 . The cementitious composition of claim 9 , wherein said synthetic fiber material has a thickness of between 1.0 and 3.5 mil.
14 . A fiber reinforced concrete building product containing a matrix comprising the cured product of a mixture including hydratable cementitious material and moisture, and a synthetic fiber material dispersed within the matrix, wherein said synthetic fiber material comprises a multi-polymer blend containing a first polymer comprising polypropylene and a second polymer selected from polyethylene and polystyrene, and wherein the synthetic fiber material having undergone at least 5% fibrillation per square inch.
15 . The fiber reinforced concrete building product of claim 14 , wherein the multi-polymer blend comprises (a) a highly isotactic polypropylene homopolymer, (b) high molecular weight polypropylene homopolymer of substantially lower melt flow rate than (a), and (c) high strength linear polyethylene.
16 . The fiber reinforced concrete building product of claim 14 , further comprising at least a first body portion and a second body portion generally oriented along respective first and second non-parallel planar directions, and said first and second body portions being connected by a bend arcing through an angle of at least 45 degrees (absolute) relative to at least one of the first and second planar directions.
17 . The fiber reinforced concrete building product of claim 14 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 190 psi at 5 lbs. per cubic yard loading at 8 days cure.
18 . The fiber reinforced concrete building product of claim 14 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 140 psi at 4 lbs. per cubic yard loading at 8 days cure.
19 . The fiber reinforced concrete building product of claim 14 , wherein said synthetic fiber material exhibits a residual strength per ASTM C1399 of at least 110 psi at 3 lbs. per cubic yard loading at 8 days cure.
20 . The fiber reinforced concrete building product of claim 14 , wherein said synthetic fiber material exhibits a Young's modulus at 30% elongation of between 5.5 and 9.5 Gpa.
21 . The fiber reinforced concrete building product of claim 14 , wherein said synthetic fiber material has a thickness of between 1.0 and 3.5.
22 . A method of making fibrillated synthetic fiber material, comprising:
heating and stretching a tape of extruded film comprising a multi-polymer blend containing a first polymer comprising polypropylene and a second polymer selected from polyethylene and polystyrene, effective to orient the film in the direction of advancement;
passing the oriented tape around and in contact with part of the periphery of a pinned rotary member having pin density of at least about 3.5 pins per square cm and at a pin rate of at least about 30 percent, effective to provide a synthetic fiber material having undergone at least 5% fibrillation per square inch.
23 . The method of claim 22 , wherein the pin density is at least about 5.5 pins per square cm and the pin rate is at least about 40 percent.