Advanced fiber reinforced concrete mix designs and admixtures systems
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.
1. A concrete mix comprising sand, aggregates, binder, fibers, and various admixtures,
having a consistency from concrete-slump class S2 to slump-flow class SF3, based on European Standard concrete slump test,
a compressive strength in the range of 30-80 MPa and
a ductility represented by the following values:
30<compressive strength (fc)<80 MPa
3<flexural strength (ffl)<12 MPa
3<strength for Crack Mouth Opening Device (CMOD) at 0.5 mm (fRl)<12 MPa
2.5<strength for CMOD at 2.5 (fR3)<15 MPa,
wherein
the concrete mix contains at least 390 Kg of binder per m 3 of the concrete mix,
the concrete mix comprises a paste volume of 300-600 liters,
the concrete mix contains at least two systems of fibers A and B,
wherein the fibers system A comprises metallic fibers with a dosage of 25-100 kg/m3 with respect to the concrete mix and mechanical resistance of at least 1200 MPa,
wherein the fibers system B comprises mono- or multifilament fibers and have a dosage of 0.2%-0-9% by volume 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 sub-admixture system I comprises at least 2 polycarboxylic acid co-polymers (PCE) selected from the group consisting of a water reducer PCE and a workability retention PCE,
wherein the sub-admixture system II is a stabilizer 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, 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 , wherein 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 a dosing of the sub-admixture system I is of 0.5-5% weight percent with respect to the binder content and the dosing of the sub-admixture system II is of 0.1-2% weight percent with respect to the binder.
7. Concrete mix according to claim 1 wherein a dosing of the sub-admixture system I is of 0.1-1% weight percent with respect to the binder content and the dosing of the sub-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 a sub-admixture system III, wherein the sub-admixture system III is 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 sub-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 a dosage of fibers system C is of 0.02% to 2% volume with respect to the concrete.