ADVANCED FIBER REINFORCED CONCRETE MIX DESIGNS AND ADMIXTURES SYSTEMS

Abstract

A concrete mix having sand, fine aggregates, binder, fibers, and various admixtures is provided. The mix has a consistency from S2 to SF3, a compressive strength in the range of 30-80 MPa and a ductility represented by fc, ffl, fR1 and fR3 values, wherein the concrete mix contains at least 390 Kg of binder, the concrete mix has a paste volume of 300-600 liters, the concrete mix contains at least two systems of fibers and a general admixture system that is composed of at least 2 sub-admixture systems.

Claims

1. A concrete mix comprising sand, fine aggregates, binder, fibers, and various admixtures, having a consistency from S2 to SF3, a compressive strength in the range of 30-80 MPa and a ductility represented by the following values: 30<fc<80 MPa 3<ffl<12 MPa 3<fR1<12 MPa 2.5<fR3<15 MPa wherein the concrete mix contains at least 390 Kg of binder, the concrete mix comprises a paste volume of 300-600 liters, the concrete mix contains at least two systems of fibers A and B, the fibers system A consists of metallic fibers with a dosage of 25-100 kg/m3 with respect to the concrete mix and mechanical resistance of at least 1200 MPa, the fibers system B have a dosage of 0.2%-0-9% by m.sup.3 of the concrete mix, the concrete mix contains a general admixture system that is composed of at least 2 sub-admixture systems I and II, wherein the first Admixture system I comprises at least 2 polycarboxylic acid co-polymers (PCE), a strong water reducer PCE and a workability retention PCE, wherein the second Admixture system II is a stabilizer obtained from a compound selected from the group consisting of modified cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, natural starch, modified starch, branched modified starch, naturals gums, Xanthan gum, fine silica, colloidal silica, silica fume and any combination thereof.

2. Concrete mix according to claim 1, further comprising coarse aggregates.

3. Concrete mix according to claim 1, characterized in that the fibers of fibers system A have a length of 35-100 mm.

4. Concrete mix according to claim 1, wherein the fibers system B comprises 65-90% in volume of metallic fibers.

5. Concrete mix according to claim 4, wherein the metallic fibers have a length of 5-35 mm.

6. Concrete mix according to claim 1, wherein the dosing of the Admixture system I is of 0.5-5% weight percent with respect to the binder content and the dosing of the admixture system II is of 0.1-2% weight percent with respect to the binder.

7. Concrete mix according to claim 1, wherein the dosing of the Admixture system I is of 0.1-1% weight percent with respect to the binder content and the dosing of the admixture system II is of 0.1-0.5% weight percent with respect to the binder.

8. Concrete mix according to claim 1, wherein the concrete mix comprises an admixture system III, wherein the third Admixture system III is obtained from a compound selected from the group consisting of cellulose microfibers, synthetic waxes, natural waxes, superabsorbing polymers, starch crosslinked polymers, acrylate crosslinked polymers, hexylene glycol (2-Methyl-2,4-pentanediol) and any combination thereof and the dosage of the admixture system III is of 0.3-6 weight percent with respect to the binder.

9. Concrete mix according to claim 1, wherein fibers system C, comprising synthetic fibers, is added to the concrete mix.

10. Concrete mix according to claim 9, wherein the dosage of fibers system C is of 0.02% to 2% volume with respect to the concrete.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0140] FIG. 1. Flexural test results showing Crack Mouth Opening (CMOD) versus Strength according to EN 14651. This FIGURE shows the values ffl, fR1 and fR3.

EXAMPLES OF THE INVENTION

[0141] Various examples of mix designs and corresponding results are presented here according to the invention.

Example 1

[0142]

TABLE-US-00008 Material Unit Quantity Total binder content kg/m3 390 CEM II 32.5 N A-LL kg/m3 390 w/b eff 0.4 Admix System I % total binder content 0.80% Admix System II % total binder content 0.30% Sand 0/4 round kg/m3 736 Fine aggregates gravel 4/8 round kg/m3 461 Coarse aggregates gravel 8/16 round kg/m3 646 Fiber type A - l/d = 65-l = 60 mm, % volume 1.00% US = 1350 Mpa, YS = 1200 Mpa hooked Fiber type B - steel - l/d = 60-l = % volume 0.20% 16 mm, US = 2350 Mpa, YS = 2100 MPa straight Entrained air l/m3 25 Paste volume l/m3 308.87 Results Unit Value Slump class S3 Slump flow mm 145 Workability retention min 80 fc Mpa 32 ffl Mpa 4.1 fr1 Mpa 3.6 fr3 Mpa 3.9 E modulus Gpa 27.9

[0143] This example with a low paste volume enable to achieve SF2 slump class (or consistency). In this example, only steel fibers are used in Fiber system B.

Example 2

[0144]

TABLE-US-00009 Material Unit Quantity Total binder content kg/m3 430 CEM I 42.5 N kg/m3 300 Fly ash kg/m3 130 w/b eff 0.55 Admix System I % total binder content 0.10% Admix System II % total binder content 0.20% Sand 0/4 round kg/m3 735 Fine aggregates gravel 4/8 round kg/m3 327 Coarse aggregate gravel 8/11 crushed kg/m3 573 Fiber type A - l/d = 50-l = 55 mm, % volume 0.35% US = 1780 Mpa, YS = 1530 MPa hooked Fiber type B - glass - l/d = 57-l = % volume 0.20% 12 mm, US = 1650 Mpa, straight Entrained air l/m3 20 Paste volume l/m3 385.90 Results Unit Value Slump class S4 Slump mm 165 Workability retention min 85 fc Mpa 35.2 ffl Mpa 3.9 fr1 Mpa 3.3 fr3 Mpa 3.6 E modulus Gpa 27.2

[0145] This other example uses only metallic fibers in Fiber system B.

Example 3

[0146]

TABLE-US-00010 Material Unit Quantity Total binder content kg/m3 510 CEM II 42.5 R/A-P kg/m3 330 Fly ash kg/m3 130 Silica fume kg/m3 50 w/b eff 0.45 Admix System I % total binder content 1.30% Admix System II % total binder content 1.30% Admix System III % total binder content 2.80% Gluconate retarder % total binder content 0.20% Sand 0/2 round kg/m3 311 Sand 0/4 crushed kg/m3 543 Fine aggregates gravel 4/7 crushed kg/m3 389 Coarse aggregates gravel 6/12 crushed kg/m3 311 Fiber type A - l/d = 80-l = 44 mm, % volume 0.35% US = 2540 Mpa, YS = 2350 MPa, hooked Fiber type A - l/d = 90-l = 50 mm, % volume 0.25% US = 3020 Mpa, YS = 2860 Mpa, hooked Fiber type B - steel - l/d = 60-l = % volume 0.20% 6 mm, US = 2130 Mpa, YS = 1810 MPa, straight Entrained air l/m3 12 Paste volume l/m3 423.16 Slump class SF3 Slump flow mm 810 Workability retention min 120 Results Unit Value fc Mpa 57.9 ffl Mpa 6.8 fr1 Mpa 8 fr3 Mpa 7.8 E modulus Gpa 30.7

[0147] This example shows an alternative according to the inventions with 2 different types of metallic fibers used in fibers system A and only steel fibers in Fibers system B.

Example 4

[0148]

TABLE-US-00011 Material Unit Quantity Total binder content kg/m3 520 CEM III/A 42.5 N kg/m3 400 Limestone Filler kg/m3 120 w/b eff 0.4 Admix System I % total binder content 0.80% Admix System II % total binder content 0.48% Admix System III % total binder content 5.10% Sand 0/4 round kg/m3 1021 Fine aggregates gravel 4/9 Crushed kg/m3 682 Fiber type A - l/d = 50-l = 50 mm, % volume 0.35% US = 1250 Mpa, YS = 1080 MPa, straight Fiber type B - Basalt - l/d = 1100-l = % volume 0.35% 12 mm, US = 3500 Mpa, straight Entrained air l/m3 34 Paste volume l/m3 417.59 Results Unit Value Slump class S4 Slump mm 175 Workability retention min 60 fc Mpa 51.2 ffl Mpa 5.7 fr1 Mpa 5.1 fr3 Mpa 4.7 E modulus Gpa 34.9

[0149] This example uses only mineral fibers (basalt) in the Fibers system B.

Example 5

[0150]

TABLE-US-00012 Material Unit Quantity Total binder content kg/m3 650 CEM I 42.5 R kg/m3 400 Silica fume kg/m3 70 GGBS kg/m3 180 w/b eff 0.38 Admix System I % total binder content 3.70% Admix System II % total binder content 1.80% Admix System III % total binder content 0.70% Sand 0/1 round kg/m3 308 Sand 0/4 crushed kg/m3 228 Fine aggregates gravel 2/6 round kg/m3 403 Coarse aggregates gravel 4/13 round kg/m3 403 Fiber type A - l/d = 92-l = 60 mm, % volume 0.70% US = 2470 Mpa, YS = 2250 MPa, hooked Fiber type B - Steel - l/d = 60-l = % volume 0.25% 30 mm, US = 2850 Mpa, YS = 2650 hooked Fiber type B - Aramid - l/d = 100-l = % volume 0.10% 18 mm, US = 4500 Mpa, straight Entrained air l/m3 17 Paste volume l/m3 484.66 Results Unit Value Slump class SF1 Slump mm 600 Workability retention min 120 fc Mpa 78 ffl Mpa 11.4 fr1 Mpa 11.6 fr3 Mpa 14.3 E modulus Gpa 41.2

[0151] Example of very high ductility concrete, with 2 types of high strength fibers in Fibers system B (steel and aramid).

Example 6

[0152]

TABLE-US-00013 Material Unit Quantity Total binder content kg/m3 500 CEM II/A-T 42.5 N kg/m3 300 Fly ash kg/m3 200 w/b eff 0.49 Admix System I % total binder content 0.90% Admix System II % total binder content 0.20% Admix System III % total binder content 2.50% Accelerator - calcium formate % total binder content 2.00% Sand 0/4 round kg/m3 703 fine and coarse Gravel 4/12 round 861 Fiber type A - l/d = 50-l = 50 mm, % volume 0.50% US = 1220 Mpa, YS = 1070 MPa, hooked Fiber type B - Steel - l/d = 80-l = % volume 0.25% 30 mm, US = 3020 Mpa, YS 2810 = MPahooked Fiber type B - Glass - l/d = 80-l = % volume 0.10% 30 mm, US = 3020 Mpa, Entrained air l/m3 24 Paste volume l/m3 447.57143 Results Unit Value Slump class S5 Slump flow mm 220 Workability retention min 45 fc Mpa 46 ffl Mpa 4.9 fr1 Mpa 5.4 fr3 Mpa 5.7 E modulus Gpa 28.5

[0153] Example according to the invention where the Fibers system B contains both metallic and glass high strength fibers and a strength accelerator using calcium formiate in the admixtures system.

Example 7

[0154]

TABLE-US-00014 Material Unit Quantity Total binder content kg/m3 430 CEM II 32.5 B-LL kg/m3 280 Fly ash kg/m3 150 w/b eff 0.58 Admix System I % total binder content 1.70% Admix System II % total binder content 0.60% Sand 0/3 round kg/m3 725 Fine aggregates gravel 3/10 round kg/m3 403 Coarse aggregates gravel 10/20 round kg/m3 484 Fiber type A - l/d = 65-l = 55 mm, % volume 0.30% US = 1570 Mpa, YS = 1380 MPa, hooked Fiber type B - Steel - l/d = 55-l = % volume 0.20% 18 mm, US = 2360 Mpa, YS = 2130 MPa, straight Fiber type C - Polypropylene - l/d = % volume 0.28% 80-l = 50 mm, US = 750 Mpa, straight Entrained air l/m3 26 Paste volume l/m3 431.23 Results Unit Value Slump class SF2 Slump mm 710 Workability retention min 90 fc Mpa 34.9 ffl Mpa 3.5 fr1 Mpa 3.1 fr3 Mpa 4.7 E modulus Gpa 25.7

[0155] This mix design according to the invention includes the Fiber system C with synthetic low resistance fibers (Polypropylene) specifically designed for fire resistance applications.

Example 8

[0156]

TABLE-US-00015 Material Unit Quantity Total binder content kg/m3 390 CEM II 32.5 N A-LL kg/m3 390 w/b eff 0.4 Admix System I % total binder content 0.80% Admix System II % total binder content 0.30% Sand 0/4 round kg/m3 736 Gravel 4/8 round kg/m3 461 Gravel 4/16 round kg/m3 646 Fiber type A - l/d = 85-l = 50 mm, % volume 0.50% YS = 670 MPa, US = 755 Mpa, straight Fiber type B - Steel - l/d = 60-l = % volume 0.25% 20 mm, YS = 2740 Mpa, US = 3020 Mpa, hooked Fiber type B - Glass - l/d = 57-l = % volume 0.05% 12 mm, US = 2750 Mpa, straight Entrained air l/m3 32 Paste volume l/m3 311.81 Slump class S3 Slump mm 120 Workability retention min 80 fc Mpa 31.2 ffl Mpa 3.5 fr1 Mpa 2.1 fr3 Mpa 1.4 E modulus Gpa 26.7

[0157] This example shows that the ductility and mechanical resistance requirements are not achieved since the fibers in fibers system A have a resistance (YS and US) that are not matching the invention.

Example 9

[0158]

TABLE-US-00016 Material Unit Quantity Total binder content kg/m3 390 CEM II 32.5 N A-LL kg/m3 390 w/b eff 0.4 Admix System I % total binder content 0.80% Admix System II % total binder content 0.30% Sand 0/4 round kg/m3 736 Gravel 4/8 round kg/m3 461 Gravel 4/16 round kg/m3 646 Fiber type A - l/d = 85-l = 50 mm, % volume 0.40% YS = 1680 Mpa, US = 1845 Mpa, hooked Entrained air l/m3 32 Paste volume l/m3 311.81 Slump class S4 Slump mm 170 Workability retention min 80 fc Mpa 31.2 ffl Mpa 3.8 fr1 Mpa 1.4 fr3 Mpa 0.8 E modulus Gpa 27.3

[0159] Example 9 shows that a typical concrete mix design containing only fibers system A (although with high resistance) that is a reference on the market. Example evidences the need for fibers system B to achieve the level of ductility according to the invention.

[0160] It is clear that the invention is not limited to the provided examples and that the selection of the various ingredients depend on the final application, placing and mechanical targeted properties and cost of the mix design.