ES2673396B2 - SIDERURGIC CONCRETE REINFORCED WITH FIBERS - Google Patents

Abstract

The invention provides a concrete prepared from slag of electric arc furnace (EHEA) reinforced with fibers, which can be of the metallic or synthetic type, so that said concrete has optimum resistance, ductility, toughness and durability properties for its use in pavements under viable techniques and of immediate application in civil engineering, complying with the requirements established in the application regulations, reusing waste from the steel industry and avoiding the disadvantages of known concrete of the current state of the art.

Description

5

10

fifteen

twenty

25

30

35

SIDERURGIC CONCRETE REINFORCED WITH FIBERS

DESCRIPTION

TECHNICAL FIELD OF THE INVENTION

The present invention is framed in the field of Construction and Civil Engineering, in the field of New Materials, and in the Technical Sector of Recycling and Use of Waste from other industrial activities.

Thus, the invention provides a fiber reinforced steel concrete, this is a concrete that includes black arc furnace slag (EHEA) in partial replacement of natural arid components, which is also reinforced with metal or synthetic fibers. The concrete of the invention has optimum resistance, ductility, toughness and durability properties for use in pavements under viable techniques and of immediate application in civil engineering, complying with the requirements established in the application regulations.

Likewise, the invention relates to the use of steel reinforced concrete in screeds or pavements reinforced with fibers in place of the distribution mesh.

BACKGROUND OF THE INVENTION

The social requirement of environmental protection and sustainable development, leads us to the need to preserve natural resources, reduce the dumping of waste and reuse and recycle industrial waste and by-products, thus managing to control environmental pollution and the overexploitation of resources.

Many of the industrial waste contains a high amount of recyclable elements and can be a very low cost source of raw material. This is the case of the black slag electric arc furnace (EHEA), which, if it is an impacting residue for the natural environment, can become a useful resource for obtaining alternative materials to those manufactured with traditional materials and techniques.

5

10

fifteen

twenty

25

30

35

The phase of fusion of scrap metal in the steel mills of Spain leaves an amount of more than one million tons per year of Black Slag from Electric Arc Furnace. There are several investigations that study the application of this black slag, such as the manufacture of conventional concrete, mortar manufacturing, manufacturing of bituminous mixtures, use in base layers and sub-base of roads, in railways, etc ... [by example, Akinmusuru, JO, “Potential beneficial uses of steel slag wastes for civil engineering purposes”, Resources, Conservation and Recycling, 1991, 5 (1): p. 73-80; Fronek, B.A., “Feasibility of Expanding the use of Steel Slag as a Concrete Pavement Aggregate”, 2012, PhDT Cleveland State University; García, C., J.T. San José and J.I. Urreta, “Reuse and valorization in civil works of electric arc furnace (EAF) slag produced in CAPV”, Waste Treatment and clean Technology (REWAS, 1999, San Sebastian; Rubio, AR and JG Carretero, “The application of steel slag on roads ”, Civil Engineering, 1991. 80: p. 5-9; Serjun, VZ, B. Mirtic and A. Mladenovic,“ Evaluation of ladle slag as a potential material for building and civil engineering ”, Materiali in Tehnologije, 2013 , 47 (5): p. 543-550).

Despite these applications, HEA black slag preparations continue to exist, which drives the search for new alternatives to such waste that helps reduce them.

On the other hand, the world of construction requires a lot of material. Aggregates constitute, by definition, a product made from natural or industrial materials. They form the basis of most civil engineering structures and their annual consumption in the European Union is estimated at around 3 billion tons per year. In Spain in particular, this figure reaches 90 million tons per year. Traditionally, all this raw material comes directly from solid rocks or alluvium. In order to prevent the overexploitation of quarries and at the same time reduce the volume occupied by industrial waste, it seems logical that the world of industry is looking for substitutes for natural materials.

Until recently, research contemplated the application of steel concrete with a non-structural nature. However, in the construction of the “KUBIK” building, it has been used with structural function in the execution of the foundation slab and basement walls (Arribas, I. et al., “Application of steel slag concrete in the foundation slab and basement wall of the Tecnalia kubik building ”, 6th

5

10

fifteen

twenty

25

30

35

European Slag Conference Proceedings, 2010, Madrid, Euroslag), likewise recent research shows a high mechanical resistance and a progressive increase of it during its first year of curing (Polanco, JA et al., "Strength and durability of concrete made with electric steelmaking slag ”, ACI Materials Journal, 2011, 108 (2): p.196-203).

Some of the disadvantages that black slag causes in this type of concrete is, due to its great porosity and angularity, the decrease in workability in the fresh mix (Etxeberria, M. et al., "Properties of concrete using metallurgical industrial by-products as aggregrates ”, Construction and Building Materials, 2010, 24 (9): p.1594-1600) In spite of this, Manso et al. (Manso, JM et al.," Design and elaboration of concrete mixtures using steelmaking slags ”, ACI Materials Journal, 2011, 108 (6): p.673-681) concluded that it is possible to manufacture concrete with 100% thick steel aggregate and up to 65% fine steel aggregate, completing fine granulometry with natural siliceous aggregate.

On the other hand, during the hardening of concrete, the appearance of microcracks generated by the retraction of the material, typical of fragile matrices such as concrete, is frequent. Fiber reinforced concrete (HRF) is defined, according to EHE-08, annex 14 (Instruction for the realization of structural concrete works, M. de Fomento, 2008, Permanent Concrete Commission, Madrid), as those concretes included in its composition short, discrete and randomly distributed fibers in its mass.

The incorporation of fibers in conventional concrete provides a more ductile behavior, increasing its toughness, improving its resistance to flexotraction and decreasing its cracking by retraction (Bemal, S. et al., "Mechanical behavior of Steel fiberreformed alkali activated slag concrete ”, Building Materials, 2009, 59 (293): p. 53-62; Yazici, S. et al," Effect of aspect ratio and volume fraction of Steel fiber on the mechanical properties of SFRC ", Construction and Building Materials , 2007, 21 (6): p. 1250-1253; Turmo et al., "Study of the shear behavior of fiber reinforced concrete beams", Building Materials, 2008, 58 (292): 9. 5-13). Fiber reinforced concrete can be used, reducing or even eliminating conventional reinforcement, in applications such as shotcrete or flooring.

For the above, and taking into account that an effective system for

5

10

fifteen

twenty

25

30

35

stopping the propagation of the microcracks generated by the retraction is the incorporation of fibers as a reinforcing component, the present invention aims to manufacture steel concrete with good mechanical properties for use in pavements, by incorporating fibers into the mixture, which can be of the type metallic or synthetic

In addition, the present invention solves the problems of recycling waste materials in the steel industry. All this is compatible with an economic profitability and a process of simple obtaining and available to anyone, so that the proposal is attractive for its application.

Another advantage is the decrease in the energy required for its manufacture, by including in its composition industrial waste by-products as an alternative to traditional mineral loads, reducing the energy used in the aggregate extraction process.

DESCRIPTION OF THE INVENTION

The present invention is established and characterized in the independent claims, while the dependent claims describe other features thereof.

In one aspect, the object of the invention is to provide a concrete with electric arc furnace slag (EHEA) reinforced with fibers, which can be of the metallic or synthetic type, so that said concrete has strength, ductility, toughness properties. and optimum durability for use on pavements under viable techniques and for immediate application in civil engineering, complying with the requirements established in the applicable regulations and avoiding the aforementioned disadvantages of known concrete of the current state of the art.

In another aspect of the invention, a technically possible exit to the slag of HEA is provided, partially replacing the use of natural aggregates, thereby contributing to minimizing the exploitation of natural resources.

Thus, with reference to the first aspect of the invention, this refers to a steel reinforced concrete reinforced with fibers, metallic or synthetic, comprising a mixture of

5

10

fifteen

twenty

25

30

35

cement, steel aggregates, siliceous sands, water, superplasticizing additives and different proportions and types of metallic or synthetic fibers.

The concrete of the present invention has the following advantages over conventional concrete with fibers and steel concretes:

- Increased resistance to the appearance of the crack;

- Increase in the toughness of steel concrete;

- Improvement of the mechanical strengths of concrete (compressive, flexural, indirect tensile strength);

- Increased impact resistance, both until the appearance of the first fissure and until breakage.

DETAILED EXHIBITION OF THE INVENTION

In the present description, reference is made to the electric arc furnace slag with its acronym EHEA, these slags constituting the steel aggregate.

In the context of the description, the term "steel concrete" refers to a concrete with aggregate from steel production.

Similarly, in this context, the term "fibers" means elements of short length and small section that serve as reinforcement to concrete, "superplasticizer" refers to an additive that gives the concrete better workability and pumpability, "siliceous sands" refers to fine aggregate of siliceous nature.

As mentioned above, the present invention relates to a steel concrete reinforced with metal or synthetic fibers, comprising a mixture of cement, steel aggregates, siliceous sands, water, superplasticizer additives and metal or synthetic fibers, where steel aggregates they have a particle size distribution of coarse aggregate (granulometry 10-20 mm) and medium aggregate (4-10 mm) and sand (0-4 mm) and are present in a coarse / medium aggregate ratio: sand: cement of 3 : 3: 1, where the proportion of superplasticizer with respect to cement is 1 to 1.5% by weight, the proportion of metallic or synthetic fibers ranges between 0.30 and 0.60% by volume with respect to concrete, the water: cement ratio is 0.5 by weight and the sand includes 50% by weight of siliceous sands of granulometry 0-4 mm.

In one embodiment of the invention, the cement used to obtain the steel concrete is a Portland CEM I 42.5 R cement whose main constituent compounds, detected by X-ray fluorescence (FRX) analysis techniques, are CaO (60.4%), SiO2 (21.3%), Al2O3 (6.1%), Fe2O3 (4.0%) and in smaller proportions others such as Mg and Na, 95% Clinker and 5% limestone charge . Density of 3.15 g / cm3 and Blaine specific surface area of 3,400 cm2 / g.

In another embodiment, the superplasticizer used in the steel concrete 10 of the invention is an aqueous-based modified superplasticizer with an approximate density of 1.08 g / cm 3, an approximate pH of 5 and a solids content of 36%.

The chemical characterization of the different steel aggregate samples was carried out by X-ray fluorescence and is shown in the following table 1.

fifteen

Table 2 shows the physical-mechanical characterization of EHEA steel aggregates, including a comparison with the limits established in the reference regulation “Structural Concrete Instruction” (EHE-08) ”(REAL DECREE 1247/2008, of 18 July, which approves the instruction of structural concrete 20 (EHE-08)).

Table 1:

Chemical characterization of steel aggregates

 % weight

 Component (% weight)

 EHEA 0-4 mm EHEA 4-10 mm EHEA 10-20 mm medium

 CaO

 27.9 27.3 27.9 27.70

 Fe2O3

 27.0 26.7 26.8 26.83

 SiO2

 19.1 19.0 19.2 19.10

 Al2O3

 13.5 13.9 13.8 13.73

 MnO

 5.4 5.6 5.1 5.36

 C2O3

 2.5 2.8 2.2 2.48

 MgO

 2.4 2.5 2.7 2.53

 C

 0.33 1.11 0.05 0.50

 S

 0.109 0.108 0.125 0.11

Table 2:

Physical-mechanical characterization of steel aggregates

 Property and regulations

 Black slag EHEA Limits EHE-08

 0/4 4/20 Frac. fine Frac. gross

 Bulk density of particles (Kg / m3) UNE-EN 1097-6

 3640 3510

 Particle density after drying in an oven (Kg / m3) UNE-EN 1097-6

 3510 3130

 Density of saturated particles with dry surface (Kg / m3) UNE-EN 10976

 3540 3240

 Water absorption (%) UNE- EN 1097-6

 1.12 3.51 <5 <5

 Weight loss in five cycles of magnesium sulfate (%) UNE-EN 1367-2

   1.65 <18

 Friability coefficient (%) UNE-EN 1097-1

 - 15.40 - <40

 Loss of Angels (%) UNE-EN 1097-2

 - 23.87 - <40

 Index of Lajas (%) UNE-EN 933-3

 - 2.80 - <35

 Sand equivalent (%) UNE-EN 933-8

 98 -> 70-75 -

 Lumps of clay (%) UNE 7133

 Absence Absence <1 <0.25

In another embodiment of the invention, the siliceous sands of size 0-4 mm 5 used in the steel concrete of the invention have a fine content according to UNE-EN-933-1 of 1.58% and an equivalent of sand according to UNE-EN 933-8 of 89. The properties of siliceous sand are shown in table 3 below.

Table 3:

10 Properties of siliceous sand

 Property and regulations

 Silica sand 0-4 mm

 Organic matter (%) UNE-EN 1744-1

 more clear

 Particles under specific gravity (%) UNE-EN 1744-1

 0.00

 Total sulfur content (%) UNE-EN 17441

 0.0014

 Acid soluble sulfates (%) UNE-EN 1744-1

 0.00

 Chlorides (%) UNE-EN 1744-1

 0.0021

 Sand equivalent (%) UNE-EN 933-8

 89

 Content in fines (%) UNE-EN 933-1

 1.58

As mentioned above, the steel concrete of the invention is reinforced with fibers, which may be metallic or synthetic.

5

10

 RL-45/50-BN steel metal fibers

 Length (mm)

 fifty

 Diameter (mm)

 1.05

 Length / Diameter

 Four. Five

 Slenderness

 48

 Density (Kg / m3)

 7900

 Tensile strength (MPa)

 > 1000

 Young's Module (MPa)

 210,000

 Number of fibers per kg

 2800

 Wire length in 1 kg (m)

 140

 Amount recommended by the manufacturer (kg / m3)

 20-60

In one embodiment of the invention, the fibers used for the manufacture of reinforced steel concrete are metal fibers, preferably loose steel fibers, especially loose steel fibers with shaped ends (RL-45/50-BN). Table 4 below shows the properties of steel metal fibers used with particular preference.

Table 4

In another embodiment of the invention, the fibers used for the manufacture of reinforced steel concrete are synthetic fibers, preferably polyolefin fibers, especially monofilament polyolefin fibers (M-48). Table 5 below shows the properties of monofilament polyolefin fibers used with particular preference.

Table 5

Chemical composition

M-48 synthetic fibers

100% polyophilic -

 homopolymer

 Transformation proccess

 Extrusion

 Density (20 ° C) (kg / m3)

 910

 Water absorption (%)

 0

 Thickness (denniers)

 Approx. 3,500

 Equivalent Diameter (mm)

 0.93

 Length (mm)

 48

 Slenderness (mm)

 60

 Fiber frequency (ud / Kg)

 32895

 Tensile Strength (MPa) ASTM D- 638

 > 400

 Elongation (%) ASTM D-638

 7

 Modulus of elasticity (GPa) ASTM D-790

 > 6

 T distortion (° C) ASTM D-648

 110

 T decomposition (° C) ASTM D-648

 280

The manufacturing process of the fiber reinforced steel concrete of the invention is not particularly limited, the usual mixing-based preparation procedures being applicable. Briefly, aggregates 5 and dry cement are mixed first. Subsequently, the water is given slowly so that it is distributed homogeneously in the mixture and, subsequently, the plasticizer is added, which can also be mixed with the kneading water. Finally, the corresponding amount of metallic or synthetic fibers is added, distributing them evenly in the mixture, and kneading them until a perfect dispersion 10 is present in the mixture.

The following table 6 shows several examples of the realization of steel concrete reinforced with metallic fibers (EM1 and EM2) and with synthetic fibers (ES1 and ES2), obtained according to the process described above, with the following compositions:

fifteen

Table 6

 Dosage

 EM1 EM2 ES1 ES2

 Cement: C (Kg)

 363 363 363 363

 Water (l)

 181 181 181 181

 0-4 mm siliceous arid (Kg)

 498 498 498 498

 Slag aggregate 0-4 mm (Kg)

 514 514 514 514

 Fine slag aggregate 4-10 mm (Kg)

 669 669 669 669

 Coarse slag aggregate 10-20 mm (Kg)

 550 550 550 550

5

10

fifteen

twenty

25

Superplasticizer 1-1.5% C (Kg) 5.44 5.44 5.44 5.44

Metallic Fibers (Kg) 30 45 - -

Synthetic Fibers (Kg) - - 3.5 5

Referring now to the mechanical properties of the fiber reinforced steel concrete of the invention, tests were carried out to check the degree of compactability of the fresh concrete according to the UNE EN 12350-4 standard (test 1), its density (UNE 12350-6, test 2), MIP mercury intrusion porosimetry tests (test 3, a) minimum pore diameter, b) maximum pore diameter, c) microporosity), its resistance to water penetration by capillary adsorption according to UNE 83982 (test 4), as well as compressive strength tests (UNE EN 12390-3, test 5), flexural (UNE 83509, test 6), indirect tensile (UNE 12390-6, test 7), modulus of elasticity (UNE 83316, test 8), compression toughness (UNE 83508, test 9), first crack resistance and flexural strength (UNE 83510, test 10, a) first crack load, b) first crack resistance, c) flexural strength) and impact resistance (UNE 83514, ens a or 11, a) number of blows at first crack, b) number of blows until break), both for the concrete of the invention reinforced with metal fibers and for reinforced with synthetic fibers.

The results of these tests are shown in Tables 7 and 8 below (the values quoted correspond to the average value of the samples tested).

Table 7:

Mechanical properties of concrete reinforced with synthetic fibers (ES) according to the

invention

 Essay 1

 Test 2 (kg / m3) Test 3 Test 4 (min / cm2)

 1.18

 2852 a) (nm) b) (nm) c) (%) 558.40

 3.60

 216081.10 11.48

 Trial 5 (MPa)

 Test 6 (MPa) Test 7 (MPa) Test 8 (Mpa)

 7 days

 28 days 90 days 28 days 28 days 34000

 53.31

 57.70 62.52 6.37 5.42

 Trial 9 (Nmm)

 Trial 10 Trial 11

 1887900

 a) (KN) b) (MPa) c) Nmm) a) b)

 25.16

 7.55 35000 24 88

Table 8:

Mechanical properties of metal fiber reinforced concrete (EM) according to the invention

 Essay 1

 Test 2 (kg / m3) Test 3 Test 4 (min / cm2)

 1.16

 2865 a) (nm) b) (nm) c) (%) 558.40

 3.60

 215 992.4 10.27

 Trial 5 (MPa)

 Test 6 (MPa) Test 7 (MPa) Test 8 (Mpa)

 7 days

 28 days 90 days 28 days 28 days 40,000

 60.25

 67.85 80.55 6.35 6.94

 Trial 9 (Nmm)

 Trial 10 Trial 11

 1949300

 a) (KN) b) (MPa) c) Nmm) a) b)

 23.15

 7.85 39230 46 155

In order to compare the properties of the fiber reinforced steel concrete 10 of the invention, applying the same procedure indicated above, two comparative samples were obtained, the first (P) as a conventional concrete pattern with siliceous aggregates reinforced with metal fibers (according to dosage of

Turmo et al., See above) and the second (E) as a conventional concrete pattern with fiber-free steel aggregate.

The following table 9 shows the dosage of the concretes of the invention 5 (EM1, EM2 and ES1, ES2) and the comparatives (P, E) in the different kneaded, in Kg

for a m3 of concrete:

Table 9

 Dosage

 P E EM1 EM2 ES1 ES2

 Cement: C (Kg)

 363 363 363 363 363 363

 Water (l)

 181 181 181 181 181 181

 Silicon acid 0-4 (Kg)

 804 498 498 498 498 498

 Silicon acid 4-12 (Kg)

 574 - - - - -

 12-20 silicic acid (Kg)

 464 - - - - -

 Slag aggregate 0-4 (Kg)

 - 514 514 514 514 514

 Slag aggregate 4-10 (Kg)

 - 669 669 669 669 669

 Slag aggregate 10-20 (Kg)

 - 550 550 550 550 550

 Superplasticizer 1-1.5% C (Kg)

 3.63 5.44 5.44 5.44 5.44 5.44

 Metallic Fibers (Kg)

 30 - 30 45 - -

 Synthetic Fibers (Kg)

 - - - - 3.5 5

10 Likewise, tests 1 to 11 were carried out for the P and E standards (P conventional concrete pattern with siliceous aggregate reinforced with metal fibers and E conventional concrete pattern with steel aggregate without fibers). The results of these comparative tests are shown below:

15 Table 10:

P comparative concrete

 Essay 1

 Test 2 (kg / m3) Test 3 Test 4 (min / cm2)

 1.20

 2420 a) (nm) b) (nm) c) (%) 560

 7.30

 215152 8.20

 Trial 5 (MPa)

 Test 6 (MPa) Test 7 (MPa) Test 8 (Mpa)

 7 days

 28 days 90 days 28 days 28 days 32000

 39.59

 46.30 55.99 5.15 4.33

 Trial 9 (Nmm)

 Trial 10 Trial 11

 1625840

 a) (KN) b) (MPa) c) Nmm) a) b)

 21.60

 6.95 31800 19 50

Table 11:

Comparative concrete E

 Essay 1

 Test 2 (kg / m3) Test 3 Test 4 (min / cm2)

 1.25

 2860 a) (nm) b) (nm) c) (%) 558.40

 3.60

 216134 12.33

5

 Trial 5 (MPa)

 Test 6 (MPa) Test 7 (MPa) Test 8 (Mpa)

 7 days

 28 days 90 days 28 days 28 days 36000

 46.14

 58.80 72.11 6.30 4.20

 Trial 9 (Nmm)

 Trial 10 Trial 11

 -

 a) (KN) b) (MPa) c) Nmm) a) b)

 23.98

 7.19 8740 11 13

As derived from the results shown above regarding the fiber reinforced steel concrete of the invention (EM1, EM2, ES1, ES2) and the comparative concrete (P, E), the steel concrete of the invention has a resistance to compression at 28 days maximum on average 67.85 MPa with metal fibers and 57.70 MPa with synthetic fibers, while for the pattern with fibers

5

10

fifteen

twenty

25

30

35

comparative (P), this value is 46.30 MPa. which represents an improvement of 46.54%.

Likewise, in reference now to the flexural strength at 28 days average maximum of 6.35 MPa with metallic fibers and 6.37 MPa with synthetic fibers while, for the comparative fiber pattern (P), this value is of 5.15 MPa, which represents an improvement of 23.30%

The concrete according to the invention also improves the value corresponding to the indirect tensile strength at 28 maximum average days, of 6.94 MPa with metallic fibers and 5.42 MPa with synthetic fibers, while, for the comparative fiber pattern ( P), this value is 4.33 for P, which represents an improvement of 60.27%.

The same applies to the compression toughness of 1949300 Nmm with metal fibers and 1887900 Nmm with synthetic fibers, compared to 1625840 Nmm of the P pattern, which is an improvement of 19.89%

The resistance to the appearance of the first crack of the concrete of the invention is, on average, 7.85 MPa with metallic fibers and 7.55 MPa with synthetic fibers, higher values than those corresponding to comparative concretes (P-6 , 95 and E- 7.19).

The flexural strength of the concrete of the invention is, on average, 39.23 Nm with metal fibers and 35.00 Nm with synthetic fibers, higher values than those for comparative concrete with fibers (P-31.8).

The resistance to impact at first crack of the concrete of the invention is, on average, 46 strokes with metallic fibers and 24 strokes with synthetic fibers, values far superior to those corresponding to comparative concrete (P-19, E-11). In the case of resistance to breakage impact, it is 155 strokes with metal fibers and 88 strokes with synthetic fibers, values far superior to those found with comparative concrete (P-50, E-13).

In short, the fiber reinforced EHEA concretes described here provide notable advantages over conventional fiber reinforced concretes; in the same way, these concrete reinforced with fiber reinforced EHAE reach adequate values in properties that adapt their use as concrete

structural for use in floors and screeds that concrete with non-reinforced EHEA does not meet.

Claims (24)

5 10 fifteen twenty 25 30 35 1. - Steel reinforced concrete with metallic or synthetic fibers, comprising a mixture of cement, steel aggregates, siliceous sands, water, superplasticizer additives and metallic or synthetic fibers, where steel aggregates have a particle size distribution of coarse aggregate ( 10-20 mm granulometry) and medium aggregate (4-10 granulometry) and sand (0-4 mm) and are present in a coarse / medium arid ratio: sand: 3: 3: 1 cement, where the proportion of superplasticizer with with respect to cement is 1 to 1.5% by weight, the proportion of metallic or synthetic fibers ranges between 0.30 and 0.60% by volume with respect to concrete, the water: cement ratio is 0.5 in Weight and the fine steel aggregate includes 50% by weight of siliceous sands of granulometry 0-4 mm. 2. - Reinforced steel concrete according to claim 1, characterized in that the cement is a Portland CEM I 42.5 R X. cement with density 3.15 g / cm3 and Blaine specific surface area of 3,400 cm2 / g. 3. - Reinforced steel concrete according to claim 1, characterized in that the superplasticizer is a modified superplasticizer based on water with an approximate density of 1.08 g / cm3, an approximate pH of 5 and a solids content of 36%. 4. - Reinforced steel concrete according to claim 1, characterized in that the fibers are metallic fibers. 5. - Reinforced steel concrete according to claim 4, characterized in that the metal fibers are loose steel fibers, especially loose steel fibers with shaped ends. 6. - Reinforced steel concrete according to claim 1, characterized in that the fibers are synthetic fibers. 7. - Reinforced steel concrete according to claim 6, characterized in that the synthetic fibers are monofilament polyolefin fibers. 8. - Reinforced steel concrete according to claim 4, characterized in that 5 10 fifteen twenty 25 30 35 It has a maximum compressive strength at 28 days on average of 67.85 MPa as measured by applying the UNE EN 12390-3 standard. 9. - Reinforced steel concrete according to claim 4, characterized in that it has an average maximum flexural strength at 28 days of 6.35 MPa, as measured by applying UNE 83509. 10. - Reinforced steel concrete according to claim 4, characterized in that it has an average maximum tensile strength at 28 days average of 6.94 MPa, as measured by applying UNE 12390-6. 11. - Reinforced steel concrete according to claim 4, characterized in that it has a compressive toughness of 1949300 Nmm, as measured by applying UNE 83508. 12. - Reinforced steel concrete according to claim 4, characterized in that it has a medium resistance to the appearance of the first crack of 7.85 MPa, as measured by applying the UNE 83510 standard. 13. - Reinforced steel concrete according to claim 4, characterized in that it has an average flexural strength of 39.23 Nm, as measured by applying the UNE 83510 standard. 14. - Reinforced steel concrete according to claim 4, characterized in that the impact resistance at the first average crack is 46 strokes, as measured by applying the UNE 83514 standard. 15. - Reinforced steel concrete according to claim 4, characterized in that it has an average impact strength at 155 strokes, as measured by applying UNE 83514. 16. - Reinforced steel concrete according to claim 6, characterized in that it has a compressive strength at a maximum of 28 days on average of 57.70 MPa, as measured by applying the UNE EN 12390-3 standard. 17. - Reinforced steel concrete according to claim 6, characterized in that 5 10 fifteen twenty 25 30 It has an average maximum flexural strength at 28 days of 6.37 MPa, as measured by applying UNE 83509. 18. - Reinforced steel concrete according to claim 6, characterized in that it has an average maximum tensile strength at 28 days average of 5.42 MPa, as measured by applying UNE 12390-6. 19. - Reinforced steel concrete according to claim 6, characterized in that it has an average compression tenacity of 1887900 Nmm, as measured by applying UNE 83508. 20. - Reinforced steel concrete according to claim 6, characterized in that it has a medium resistance to the appearance of the first crack of 7.55 MPa, as measured by applying the UNE 83510 standard. 21. - Reinforced steel concrete according to claim 6, characterized in that it has an average flexural strength of 35.00 Nm, as measured by applying the UNE 83510 standard. 22. - Reinforced steel concrete according to claim 6, characterized in that the average resistance to impact at first crack is 24 strokes, as measured by applying the UNE 83514 standard. 23. - Reinforced steel concrete according to claim 6, characterized in that it has an average breaking resistance of 88 strokes, as measured by applying the UNE 83514 standard. 24. - Use of reinforced steel concrete according to any of the preceding claims in screeds or pavements reinforced with fibers in place of the distribution mesh.