HU223747B1 - Compacted rolled fibre-reinforced concrete composition and method for producing a pavement based on same - Google Patents

Abstract

The invention is a fiber-reinforced, cylinder-compacted concrete mix, which contains admixture, hydraulic binder and deformable anchoring metal fibers. The essence is that the metal fibers consist of cylindrical wires (10), they have a straight middle part (11), to both ends of which a bent end part (12) is connected through a lead-through part (13). The shape of the curved end part (12) is designed to prevent the connection of adjacent fibers. The diameter of the fibers (d) is between 0.38 and 1.05 mm, the total length is between 19 and 80 mm, the length of the end parts (l, l') is between 1.5 and 4 mm; the transverse displacement (h, h') between the middle part (11) and the end part (12) is at least 0.75 mm. Furthermore, the angle (?, ?') between the lead-through part (13) and the central part (11) is at most 160°. The minimum tensile strength of the fibers is 900N/mm2; the concrete mix contains between 180 and 400 kg of hydraulic binder per cubic meter of concrete, between 90 and 150 l of water, between 25 and 60 kg of metallic fibers, and up to 1.8% by weight of the hydraulic binder, plasticizer and/or setting delay additive. The essence of the proposed procedure is that a concrete layer is made from a cylinder-compacted, fiber-reinforced concrete mixture, the bending strength of which changes continuously in a wide range of crack opening sizes, for example, with opening sizes between 0 and 4 mm, but without breaking the fibers. ŕ

Description

FIELD OF THE INVENTION The present invention relates to a fiber-reinforced and roll-compacted concrete mix, and to a process for producing continuous pavements, industrial coatings or the like from such a concrete mix.

Roller compacted concrete mixes are known to differ from conventional cast or vibrated concrete in that they require reduced amounts of cement and water with similar mechanical properties. This reduced water content allows such concrete mixtures to be significantly more load-bearing and can therefore be applied with an asphalt finisher, i.e. asphalt paving equipment. In addition, they can be compacted with vibrators or wheeled compactors and then immediately transferred to traffic. In contrast, conventional sliding or vibrating screed equipment is usually used for pouring concrete, but pavements made in this way can only be opened to traffic after a certain period of time, which is usually at least 7 days.

It is also known that metallic fiber reinforcement is widely used in conventional concrete mixtures. These metal fibers are also widely used in the production of industrial coatings and are generally formed into 1 mm diameter drawn fibers.

The reinforcing fibers currently used differ from each other in the type of active anchoring in the concrete structure of the concrete. There are wires made with so-called deformable anchors, such as hook wires, such as commercially known as "Dramix" (marketed by the Frog), and folded wires (such as Tréfli Arbed).

The latter company also markets "Twincone" wires with non-deformable conical sections at both ends. This type of anchoring is much stiffer than anchoring with hooks or folding, which is why these wire strands are also called "fully anchored" strands.

Conventionally vibrated or cast concrete can be used after its reinforcement with steel fibers for industrial substrates or pavements (often covered with abrasive coatings, and therefore less exposed to weather and temperature changes than paving). Such industrial coverings or substrates can be made on a surface of up to 2000 m ² without joints, ie expansion joints, because the properties of the reinforcing fibers ensure the connection.

However, practical experience has shown that conventional concrete is generally not suitable for continuous paving without joints. This is due to the fact that due to the relatively high amount of cement and water in conventional concrete mixtures, hydraulic shrinkage occurs in the concrete, which is even accompanied by thermal shrinkage. Meanwhile, the mechanical stresses are such that the fibers cannot absorb it. The consequence of this is that the concrete shrinkage phenomenon leads to the formation of noticeably larger cracks, and the opening size of these cracks is often unacceptably larger than 1 mm.

Thus, it is absolutely necessary to have connections in these vibrated fiber reinforced concrete pavements to localize the shrinkage effects and reduce crack openings. This, in turn, adversely affects the economics of continuous pavement construction and significantly reduces the efficiency of the entire road construction technology.

Conventional reinforced concrete using steel wires for reinforcement is known from U.S. Pat. No. 5,866,000, and this concrete has been modified to improve the compressive strength of the concrete to greater than 80 N / mm ² . In order to increase the compressive strength, this concrete mix contained, on the one hand, 5-10% by weight of the cement, based on the weight of the cement, such as burnt silicate, and thus made it possible to fill the pole volumes in the concrete. On the other hand, since water generally has the effect of reducing the strength of concrete, the water / cement ratio (ratio) has been kept below 0.4.

However, the cited U.S. Patent states that relatively high amounts of superplasticizer must be added to the concrete mix to compensate for the presence of relatively small amounts of water, although the presence of ultrafine fillers would require the use of larger amounts of water. In the second and third examples of the cited US patent, relatively large amounts of hydraulic binders (cement and micro porcelain soil) were used, which is in contrast to the relatively reduced cement content of roller compacted concrete. In addition, the amount of plasticizer was also very high (2.5%), but such a large amount is not required for compacted concrete having a similar water / cement ratio.

Further, a process is known for the production of continuous cast concrete pavements without joints. This process is also referred to as the "Continuously Reinforced" Concrete (CRC) process, which combines steel bars, typically 16 mm steel bars, in a continuous shape over the entire length of the pavement. Once the steel reinforcing bars are laid, concrete pouring begins, and sliding paving machines are usually used. However, this procedure is quite complicated and expensive based on practical experience.

Because of the advantages of roller compacted concrete compared to traditional cast, vibrated or extruded concrete manufacturing technologies, fiber reinforced compacted concrete has been proposed, where material composition and fiber selection have been made to provide continuous pavement or industrial concrete flooring. and have limited aperture sizes.

Comparative studies were carried out on road surfaces for cracks and compared2

GB 223 747 BI needles with conventionally compacted reinforced concrete using "Twincone" fibers. On the other hand, this was also compared with compacted reinforced concrete using folded fibers and the results of these tests are summarized in Table I below.

Table 1

constant reinforced concrete Compacted concrete with folded fibers Compressed concrete with "Twinconc" fibers Number of cracks 200 m long 60 11 15 Average distance between cracks (m) 3 20 15 Average crack size (mm) 1 2.5 1 Total cracks at 200 mesh (mm) 60 27.5 15

"Continuously reinforced concrete" in the first column is a continuous concrete with no joint gaps, which according to our experiments consisted of fine and evenly distributed cracks. For compacted concrete reinforced with folded fibers (see

The second column of Table I), the cracks were spaced apart but were wide. For concrete reinforced with "Twincone" fibers (third column of Table I), the overall crack opening was 30% smaller than for folded conventional fiber.

As a result of the above experiments, the properties of fully anchored fiber reinforced concrete appear to be closer to those of continuous reinforced concrete, the anchoring effect of this fiber reinforcement being more effective than that of folded fiber reinforced concrete. Based on Table I, i.e., the experimental results, it can be established that the cracks formed in "Twincone" fiber reinforced concrete roll are essentially the same as those formed in continuous reinforced concrete.

However, it is noted that the diagram in Figure 1 illustrates the results of a comparative test, namely the tensile tests of the full anchoring effect of the Twincone fibers, herein the diagram is denoted by the reference, and the tensile strength results of the deformable anchors B. The same diameter, i.e. 1 mm, was used for both fibers. It is clear from the diagram that the use of full anchoring fibers is necessary for the seamless manufacture of continuous pavements, since these fibers are more capable of limiting the opening size of the cracks.

FR-2684397 also discloses a concrete mixture for the production of joints without joints. This concrete mix includes rigid anchoring fibers such as those disclosed in EP-130191 and EP-098825.

In the art, to improve the anchoring effect, so-called first generation cylindrical hook wires have been used in cast concrete and these hooks have been flattened. Such fibers are, for example, reinforcements known in the art as "Dramix FL 45/50", which are described in more detail in WO-97/11239.

As shown above, the current trend toward fully anchoring fibers or very rigid anchoring fibers in the construction of seamless continuous pavements is that less rigid anchor fibers such as folded or hooked fibers are only used when used in industrial coatings or vibrated concrete mix is used for screeds.

It is an object of the present invention to provide an improved fiber reinforced, roller compacted concrete mix that allows only a limited amount of crack formation, while allowing the size of the crack opening to be controlled. It is a further object of the present invention to provide an improved process for making continuous concrete or industrial pavements from such a concrete mix.

The object of the present invention has been solved by a fiber-reinforced, roll-compacted concrete mixture comprising an additive, hydraulic binder and deformable anchoring metal fibers. The concrete mixture according to the invention consists in that the metallic fibers consist of approximately cylindrical wires having an approximately rectangular center portion having a bent end portion connected to each end through a passage section and the shape of the bent end portion preventing the adjacent fibers from bonding. The fibers have a diameter of 0.38 to 1.05 mm, a total length of 19 to 80 mm, and end lengths of 1.5 to 4 mm. The transverse displacement between the middle portion and the end portion is at least 0.75 mm and the obtuse angle between the through portion and the middle portion is less than or equal to 160 °. In addition, the through portion and the end portion are obtuse to each other. Furthermore, the fibers have a minimum tensile strength of 900 N / mm ² . The recommended concrete mix is 180 to 400 kg of hydraulic binder, 90 to 150 liters of water, 25 to 60 kg of metallic fibers and up to 1.8% of the weight of the hydraulic binder plasticizer and / or curing agent per cubic meter of concrete. contains additives.

According to the invention, the hydraulic binder consists of a combination of variable proportions of cement clinker, ground slag, fly ash, gypsum (phosphor gypsum or anhydrite) and ultrafine additives (smoked silicate, porcelain solution).

Quite unexpectedly, the fibers used for the roller compacted concrete mix of the present invention have achieved surprisingly good results in crack control and crack control. Fibers used in the present invention, such as those mentioned above, which have bent ends

EN 223 747 Β1 hand and approximately cylindrical along their entire length, they are surprisingly able to achieve a balance between limiting the number of cracks and the opening size of the cracks.

Full anchoring or very rigid anchoring fibers have a high anchorage strength up to a crack of 1 mm aperture. However, if the cracks continue to open, the fibers will no longer be able to exert this strong anchoring effect, and a very rapid reduction in the crack fixing effect can be observed.

In the present invention, the fibers provide a very strong anchoring effect up to an opening size of 1 mm of cracks, which is practically equivalent to a full anchoring effect. However, the anchoring feature can be maintained even with much larger crack openings, such as openings of up to 3-4 mm. The concrete mix according to the invention also exhibits a favorable extensibility property and significantly greater safety against fiber breaks at opening sizes greater than 1 mm than full anchor fibers, for example when the pavement underbody is locally collapsed and the crack sizes exceed 2 mm. t.

Preferably, the wires are comprised of fibers having a diameter of 0.65 to 0.85 mm and an overall length to diameter ratio of 65 to 85. It is particularly preferred that the fibers have an overall length / diameter ratio of about 80.

In the present invention, each of the bent end portions comprises a straight section which is connected to the middle portion through the lead-through portion and which includes at least two bends.

Preferably, the fibers have a total length of 60 mm, a diameter of about 0.75 mm, and a minimum tensile strength of 1100 N / mm ² . The advantage of such a fiber is that, when used in the same weight as the concrete mixture, it provides twice as much fiber as in the conventional solution of 1 mm fibers. Due to its higher tensile strength, the thinner fiber has a higher tensile strength than conventional 1 mm diameter fibers.

The cracks observed in concrete made from the concrete mix according to the invention generally have apertures of 0.3 to 1 mm. Thus, the size of the cracks can be effectively limited, since the particles of the concrete mix form irregular cracking surfaces and remain embedded in the matrix, which is due to the fibers anchored in the matrix of concrete on both sides of the crack. This mutual bonding effect between the concrete mixture particles and the fibers ensures that the edges of the cracks remain in a "bonded state", which means that the cracks that are controlled in accordance with the invention do not actually come off the entire structure of the pavement. Thus, the crack does not change under the heavy traffic that occurs during the continued use of the pavement. Furthermore, since the fracture edges remain mechanically embedded due to the interaction between the components of the concrete mix, the fibers are consequently subject to less fatigue load. Thus, the present invention provides surprisingly good durability for pavements. Furthermore, if the opening size of the crack is less than 1 mm, the water optionally containing salt will not flow into the crack even when it reaches the crack line. This effectively reduced the risk of fiber corrosion in the crack.

Generally, 70 to 100% crushed, i.e. crushed, material having sharp corners and edges and a particle size of 0 to 14 mm may be used as an additive to prevent segregation, i.e. separation of coarse and finer particles.

Preferably, the concrete mix according to the invention also comprises a plasticizer which facilitates a more compact placement of the components of the concrete mix, resulting in, for example, a density of the concrete of about 2400 kg / m ³ . This has the advantage of increasing strength and reducing the amount of hydraulic binder that can be used.

Preferably, the hydraulic binder content is between 250 and 300 kg per cubic meter of concrete, the water content is between 4 and 6% by weight of the dry weight of the concrete, i.e. between 100 and 150 liters per cubic meter of concrete, and its metallic fiber content is between 25 and 50 kg per cubic meter.

The metallic fiber content may optionally be between 30 and 40 kg per cubic meter of concrete. By way of example, the concrete mixture may contain 280 kg of hydraulic binder and 1101 water per cubic meter of concrete.

Preferably, the amount of plasticizer may be at least 0.3% by weight of the hydraulic binder. Optionally, a small amount of plasticizer, for example 0.3 to 0.5% by weight of the hydraulic binder, may be used for better bonding between the additive parts.

On the other hand, the bond retardant effect of concrete can be achieved, for example, by using the same product as plasticizer and bond retardant - by using a greater amount of plasticizer, for example at least 0.7% by weight of the hydraulic binder. This ensures that the fresh concrete is approx. It maintains its workability for up to 20 hours, for example, if we want to work the concrete laid the day before, even the next day.

The concrete mixture according to the invention can be used to manufacture or reinforce existing pavements which are subject to high rolling loads, for example from heavy vehicles, heavy vehicles or airplanes.

The concrete mixture according to the invention allows the laying of a concrete layer whose bending strength is constantly changing, for example in the range of 0 to 4 mm crack opening size, but without fiber breakage. Optionally, the variation in strength within this range may not differ by more than 20% from the nominal value.

HU 223 747 Β1

The concrete mixture according to the invention can be applied with a heavy finisher, which is generally used for the application of bituminous materials. The concrete can then be compacted with a multi-ton compactor which may have one or two vibrating rollers. This compaction may be followed by a kneading action with a rubber wheel compactor to which, for example, a load of 3 to 5 tons per wheel may be applied.

The fiber-reinforced compacted concrete can then be immediately covered with a bitumen layer. Concrete may be cured by applying a bitumen emulsion. The pavement thus formed includes as a base layer a concrete layer of the concrete mixture according to the invention, which is covered with a bituminous wear layer. The advantage of this is that the functions are separated, ie the concrete substrate provides the load-bearing structure even in heavy traffic with a long service life, while the bituminous top layer provides a carpet layer with special properties such as porous asphalt to bind rainwater and / or Noise Reducing Asphalt Limits Noise.

The concrete layer may be optionally covered with an optionally high cementitious microbond layer, which is actually a mixture of three components, namely cement, sand (a high proportion of fine particulate sand) and some fine aggregates with a fraction of 0.08 mm fine fraction in the sand. -20%.

Very good durability can be achieved by using the concrete mix according to the invention in the continuous production of continuous new pavements. The fiber reinforced, roller compacted concrete according to the present invention has been found to be excellent as a load-bearing structure for pavements. In addition, the method of the present invention also provides good control over the sensitivity of bituminous pavement layers to wheel tracks by applying a thin substrate of 5 to 18 cm in thickness from the concrete of the invention, which is then covered with a thin or very thin bituminous asphalt layer.

The invention will now be described in more detail with reference to the accompanying drawings, in which an exemplary embodiment of the present invention is illustrated. Further details, features, and advantages of the invention will be described below. In the drawing:

Figure 1 is a diagram illustrating the results of tensile strength tests of prior art complete anchors and deformable anchors using a uniform diameter of 1 mm;

Figure 2 is a schematic side view of a detail of a reinforcing fiber for use in a concrete mix according to the invention;

Figure 3 is a diagram illustrating the results of bending tests of prisms made from the concrete mix of the present invention and the prior art concrete mix.

As shown in Figure 2, the concrete mixture according to the invention includes reinforcing metal fibers, which in this case are wires 10 with bent end portions. The wires 10 are approximately cylindrical in shape along their entire length L and have a substantially rectilinear center portion 11 which is connected by an oblique lead-through portion 13 to the bent end portions 12. Each of the end portions 12 consists of a rectilinear portion which is connected to the middle portion 11 through the oblique passage portion 13 which has at least two bends. The diameter d of the wires 10 is selected from 0.38 to 1.05 mm. The wires 10 have a total length L of between 19 and 80 mm and a minimum tensile strength of 900 N / mm ² .

The end portions 12 of the wire 10 may be of different or identical shapes. The straight sections of the end portions 12 may have different or similar portions, and preferably have a length of 1.5 to 4 mm. The obtuse angles α or a 'of Fig. 2 are inclined at an angle of less than or equal to 160 [deg.], Which angles the oblique lead portion 13 with the rectangular center portion 11. The angles α and α can be the same or different.

One of the oblique passageways 13 of the end portions 12 need not be in the plane defined by the other intermediate passageway 13 and the rectilinear middle portion 11. However, it is to be noted that the end portions 12 need not necessarily be in the common plane defined by the lead-through portion 13 and the rectilinear middle portion 11. The offset value of the middle portion 11 and the end portions 12 displaced relative to it, respectively, may be the same or different, but preferably the size of the h or h 'values is at least 0.75 mm.

In the exemplary embodiment described, the concrete mixture according to the invention includes fibers commercially available as "Dramix 80/60". Such fibers are characterized by a total length L of 60 mm, an ad diameter of 0.75 mm, i.e. a λ ratio (L / d) of 80, and a tensile strength of at least 1100 N / mm ² . The values of the angles α and α 'may be approximately the same and the through portions, the end portions 12 and the middle portion 11 may be located approximately in the same plane.

II. As shown in Table II, different blends were prepared, with blends 1, 2 and 4 differing only in the type of fibers used. The

Mixture 1 contains fibers known as "Twincone" which are all anchored fibers; Mixture 2 comprises fibers of the type "Dramix FL 45/50" in which the fiber ends are formed as flattened hooks; The fiber content for each of the three compositions was 30 kg / m ³ . Mixture 3 contains "Dramix FL 45/50" type fibers, similar to Mixture 2, but at 35 kg / m ³ .

HU 223 747 Β1

Table 11

kg / m ³ 1. Concrete mix with "Twincone" fiber reinforcement Concrete mix 2 Dramix FL 45/50 fiber reinforcement scl 3. Concrete mix with "Dramix FL 45/50" fiber reinforcement 4. Concrete mix with 'Dramix 80/60' fiber reinforcement 5/15 gravel 1103 1103 1103 1103 0/5 sand 735 735 735 735 Cement (*) 400 400 400 400 Total amount of water 160 160 160 160 plasticizers 6 6 6 6 threads 30 30 35 30 V / C (νίζ / cement) ratio 0.4 0.4 0.4 0.4

(♦) CPA-CEM I 52.5 R cement

The above concrete mixes were assembled so that the compressed concrete had a compressive strength of between 50 and 60 MPa and a rating of NF P 98-128 for compacted concrete.

Compressive strength values were measured on specimens of dimensions 16 x 32 cm in accordance with current standards and the results of these measurements are shown in Appendix III. Table. The tests are shown in Figures 1-4. in the case of concrete mixes, we also carried out three test runs.

III. spreadsheet

Pattern 1 Pattern 2 Pattern 3 Average 1. concrete mix 50 MPa 54 MPa 50 MPa 51.3 MPa 2. concrete mix 52 MPa 52 MPa 52 MPa 52.3 MPa 3. concrete mix 61 MPa 59 MPa 57 MPa 59.0 MPa 4. concrete mix 58 MPa 57 MPa 52 MPa 55.7 MPa

To characterize the role of the fibers in their ability to maintain residual load during the cracking process in the material, bending tests were performed on prisms formed as experimental specimens. These prisms were subjected to circular bending. We chose long prisms for the size of the fibers, namely 45 by 70 cm in length, with a height of 20 cm and a width of 15 cm.

During bending tests, the distance between the points of support was 60 cm and the distance between the points of application of the load was 20 cm. 50

Each of the trial prisms was scored at a central location to localize the crack. The sensor bridging the groove was thus located directly at the crack opening.

Figure 3 is a graph showing the results of comparative bending tests, which illustrate the cracking properties of concrete when using different fibers.

The curves 1 through 4 correspond to those in Figs. concrete mixtures. 60

Approx. A load of 25 kN was applied at which a crack appeared.

The prism of the concrete mix 1 contained "Twincone" fibers, and in this prism we experienced a decrease in load immediately after the crack appeared until the crack aperture value reached 0.2 mm when the fibers were capable of loading. pick up. When the aperture value was reached about 1 mm, the maximum load-bearing capacity was reached during bending, whereby the fibers began to break, which resulted in a continuous reduction of the load and, ultimately, a very rapid reduction of the load in the prism.

The prism of the concrete mix 4 corresponds to the mixture according to the invention, where it is clearly seen that there is very little load reduction when the crack appears, and then the load applied increases. Maximum load-bearing capacity was achieved when the crack opening was between 1 and 1.5 mm. After that, the load-bearing capacity decreased very evenly and slightly.

The prism of concrete mix 2 contained 30 kg / m ³ of "Dramix FL 45/50" type fibers. This prism showed very strong load reduction (about 50% reduction) after the appearance of the crack. Curve 2 illustrates that a gradual load drop had to be considered after a 1.8 mm crack opening size. These load drops correspond to fiber breaks, as in the case of concrete mix 1.

In our tests with Prism 3 of concrete mix, we used 35 kg / m ³ of the fibers known as "Dramix FL 45/50" for the prism. The experimental results were similar to the concrete mix 2, the higher load capacity was obviously due to the increased fiber content.

After the appearance of the crack, the load-bearing capacity was approximately the same for concrete mixes 1, 3 and 4. The fibers allowed the formation of substantially identical cracks, but the size of the cracks was limited to 1 mm. Above this value, however, the behavior of the fibers changes the re6 due to tear or stretch

EN 223 747 Bl pedt section behavior. The fully anchored fiber shows the highest anchoring strength up to an opening size of 1m. If, on the other hand, the crack continues to open, the fibers will break, which is the reason for the very rapid reduction in load retention of the crack edge.

The crack has a slightly lower anchoring strength (less than about 7%) than the total anchoring fiber, up to a gap size of 1 mm. On the other hand, however, the fiber used in the present invention retains the good anchoring properties even at much larger crack openings, even with an opening size of 3-4 mm. However, this surprising additive effect is unimaginable when using full anchoring fibers or other conventional fibers.

Although the invention has been described above in connection with a particular embodiment, it will be apparent to one of ordinary skill in the art that it is not intended to be limited to this embodiment, and that many other combinations and embodiments may be practiced within the scope of the claimed application.

Claims (11)

A fiber-reinforced, roll-compacted concrete mixture comprising an additive, a hydraulic binder and deformable anchoring metal fibers, characterized in that the metal fibers consist of approximately cylindrical wires (10) having a substantially rectangular center portion (11) having a through portion (13) at each end thereof. a curved end portion (12) is connected thereto, the end portions (12) being formed to prevent adjoining fibers, the filaments having a diameter (d) of between 0.38 and 1.05 mm and a total length (L) of between 19 and 80 mm , the end portions (1, Γ) being between 1.5 and 4 mm; the transverse displacement (h, h ') between the middle portion (11) and the end portion (12) is at least 0.75 mm and the angle (a, a') between the through portion (13) and the middle portion (11) is less than or equal to 160 [deg.], The passage portion (13) and the end portion (12) being mutually obtuse, and the fibers having a minimum tensile strength of 900 N / mm <^2>; the concrete mixture contains from 180 to 400 kg of hydraulic binder, from 90 to 150 liters of water, from 25 to 60 kg of metallic fibers and up to 1.8% of the weight of the hydraulic binder plasticizer and / or curing agent per cubic meter of concrete contain. Concrete mixture according to Claim 1, characterized in that the wires (10) consist of fibers having a diameter (d) of between 0.65 and 0.85 mm and an overall length / diameter (L / d) ratio (λ). ) and between 65 and 85. The concrete mix according to claim 2, characterized in that the fibers have a total length / diameter ratio (λ) of about 80. Concrete mixture according to claim 3, characterized in that the fibers have a total length (L) of 60 mm, a diameter (d) of about 0.75 mm and a minimum tensile strength of 1100 N / mm ² . 5. Concrete mixture according to any one of claims 1 to 3, characterized in that each of the bent end portions (12) comprises a straight section which is connected to the middle portion (11) through the lead-in portion (13) and which has at least two bends. 6. A concrete mix according to any one of claims 1 to 3, characterized in that its hydraulic binder content is between 250 and 300 kg per cubic meter of concrete, its water content is between 4 and 6% by weight of dry weight of concrete, i.e. 100-150 liters per cubic meter of concrete. the metallic fiber content per cubic meter of concrete is between 25 and 50 kg. 7. A concrete mix according to any one of claims 1 to 3, characterized in that the plasticizer contains at least 0.3% by weight of the hydraulic binder. 8. A process for producing continuous road or industrial pavements without a gap, comprising the step of providing a rolled, fiber-reinforced concrete mixture according to claims 1-7. and a concrete layer having a continuously varying bending strength over a wide crack opening size range, for example at an opening size of 0 to 4 mm, but without breaking the fibers. 9. The process of claim 8, wherein the strength within said range is allowed to vary by up to 20% of the nominal value. Method according to Claim 8 or 9, characterized in that the concrete layer is covered with a bituminous wear layer or a microbeton layer, the latter being mixed with three components, namely cement, of at least 10 and 20% of fine granules of less than 0.08 mm. containing sand and other fine fractions containing sand. The method according to claim 8 or 9, characterized in that the fiber reinforced, roller compacted concrete layer is produced in a thickness of 5 to 18 cm and is used as a load-bearing structure of bituminous pavements or as a layer preventing wheel formation.