CH714974A1 - Ultra-high-performance concrete. - Google Patents

Abstract

A dry mix for producing an ultra-high strength concrete comprising: aggregate having a CaCO 3 content of at least 75%; a first filler with a grain size of 10 microns to 125 microns and a second filler with a grain size of 0.7 microns to 10 microns. The first and second filler have a CaCO 3 content of at least 75%.

Description

Description Technical field The invention relates to the field of concrete construction, in particular the field of ultra-high-strength concrete. It relates to a dry mix for the production of an ultra-high-strength concrete, a fresh ultra-high-strength concrete, and its use in concrete construction, an ultra-high-strength concrete, and a method for the production thereof.

PRIOR ART In contrast to conventional types of concrete, ultra-high-performance concrete or ultra-high-strength concrete (UHFB) is distinguished, inter alia, by a very high compressive strength of over 120 MPa. Due to the high compressive strength and strong binding effect, the UHFB does not fail when there is a crack around the aggregates, but is characterized by the fact that cracks pass through them.

Due to its greatly increased compressive strength, UHFB is particularly suitable for the production of components subject to pressure, such as columns, supports and walls, in particular high-rise buildings, bridges or tunnels. The beneficial effect of UHFB increases with increasing building height, since more stable support structures with less space are possible. In addition, the use of UHFB in building construction allows new creative and constructive solutions that cannot be implemented using other concretes due to the lack of stability. In addition to components subject to pressure, UHFB is also suitable for the production of components subject to bending, such as beams or beams, e.g. Bridges or oil platforms.

Known ultra high-strength concretes contain, in addition to cement, especially finely ground quartz sand, which is required to achieve the very high structural density. Furthermore, the ultra-high-strength concretes known in the prior art are distinguished by comparatively low water cement values (wz) of 0.3 to 0.2, as a result of which the distance between the individual cement grains is significantly reduced. While the reduction in the water cement value has an advantageous effect on the strength of the concrete, it also makes it difficult to process. For this reason, the fresh ultra-high-strength concrete or the UHFB contains relatively large amounts of superplasticizer. To avoid brittle failure and to increase stability, the ultra-high-strength concretes can contain fiber materials.

DESCRIPTION OF THE INVENTION Despite the clear advantages in comparison with the conventional types of concrete in terms of stability, weight and space requirements, no UHFB has yet been able to establish itself as a mass product. One reason for this is the complex production and the relatively high costs of the raw materials, which have to be prepared, processed and stored separately.

[0006] A significant disadvantage of the known ultra-high-strength concretes is the occurrence of the alkali-silica reaction. The calcium hydroxide of the cement reacts with the quartz to form various calcium silicates, for example wollastonite. The alkali-silica reaction is particularly problematic when the concrete is exposed to moisture, since the silicates swell strongly when absorbed in water, which can lead to cracking in the concrete. In Germany alone, the renovation needs of airport runways damaged by the alkali-silica reaction were estimated at 1.2 billion euros in 2016.

It is therefore the object of the invention to further develop the state of the art in the field of ultra-high-strength concrete and preferably to overcome disadvantages of the prior art. In advantageous embodiments, the invention provides a UHFB which has a very high resistance to the alkali-silica reaction. In a further embodiment, a UHFB that is less expensive than the prior art is provided.

Another object of the invention is to further develop the state of the art in the field of UHFB manufacturing processes. In advantageous embodiments, a particularly stable and durable UHFB can be provided by a manufacturing method according to the invention.

These objects are generally achieved by the subject matter of the independent claims.

Further advantageous embodiments result from the dependent claims and the disclosure as a whole.

In a first aspect, the invention relates to a dry mix for producing an ultra-high-strength concrete comprising an aggregate with a CaCO ₃ content of at least 75%. Furthermore, the dry mixture comprises a first filler with a grain size of essentially 10 μm to 125 μm and a second filler with a grain size of essentially 0.7 μm to 10 μm. The first and second fillers each have a CaCO ₃ content of at least 75%.

The person skilled in the art understands that, as is customary in concrete production, the specified grain sizes are a grain size distribution and thus, if appropriate, small proportions of the filler can also be below the specified range. For example, the average grain size of the second filler is preferably 2 to 6 μm.

CH 714 974 A1 [0013] In a further embodiment, a dry mix according to the invention for producing an ultra-high-strength concrete additionally comprises a binder, for example cement, lime or fly ash.

[0014] In some embodiments, the dry mix to produce an ultra high strength concrete additionally comprises a fibrous material. This fiber material can be steel fibers, carbon fibers, mineral fibers, e.g. from basalt, plastic fibers, e.g. act from polypropylene, textile fibers or glass fibers or a mixture thereof.

Typically, the dry mixture additionally comprises microsilica with a grain size of 0.1 μm to 10 μm, preferably 0.1 μm to 5 μm. By using Microsilica, the wear resistance and the service life of the UHFB according to the invention can be increased.

In a further embodiment, the dry mixture additionally comprises a deaerator, preferably an alkyl phosphate, such as, for example, triisobutyl phosphate, triethyl phosphate or tri-n-butyl phosphate. By using a deaerator, the air pore volume in the fresh ultra-high-strength concrete and ultra-high-strength concrete produced from the dry mixture is reduced. The proportion of the deaerator, based on the binder, is preferably 0.2 to 1%.

In a further embodiment, the aggregate has grain sizes of 125 μm to 2 mm, preferably 125 to 500 μm.

In a preferred embodiment, the aggregate, the first filler and / or the second filler have a CaCO ₃ content of 75% to 99%, preferably 90 to 99%, particularly preferably 93% to 99%. The aggregate, the first filler and / or the second filler are preferably resistant to the alkali-silica reaction (alkali aggregate resistant). This resistance can be achieved by the relatively low silicate and silicate rock content of the aggregate, the first filler and / or the second filler. In particular, due to the absence of large amounts of quartz sand, the aggregate, the first filler and / or the second filler is resistant to the alkali-silica reaction. The density of the first filler and / or the second filler is typically in a range from 2 to 3 g / cm ³ , preferably between 2.5 and 2.9 g / cm ³ .

In a further embodiment, the aggregate, the first filler and / or the second filler has a pyrite content of at most 0.05%, preferably of at most 0.01%. Furthermore, the sulfur content of the aggregate, the first filler and / or the second filler is below 0.1%.

In advantageous embodiments, the proportion of unsuitable sheet silicates such as mica, kaolinite, chlorite and swellable materials in the aggregate, in the first filler and / or in the second filler is below 6%. The proportion of swellable minerals is preferably less than 0.1%.

In a further embodiment, the aggregate, the first filler and / or the second filler has a silicate rock content of 0.05% to 10%, preferably 0.05% to 5%, particularly preferably 0.05 to 3%.

In a preferred embodiment, the binder comprises cement with grain sizes from 0.1 μm to 40 μm.

In a further embodiment, the binder comprises calcium sulfoaluminate. The proportion of calcium sulfoaluminate in the binder is preferably 75 to 85%.

[0024] In a preferred embodiment, the dry mixture for producing a UHFB comprises lithium carbonate. By using lithium carbonate, the processing time and the consistency of the fresh ultra high-strength concrete made from the dry mix can be regulated in time. The content of the lithium carbonate is preferably 0.1 to 1%, particularly preferably 0.5%, based on the weight of the binder.

[0025] In some embodiments, the ratio of the aggregate: first filler: second filler in the dry mixture can be essentially 8.5: 1: 0.5.

Another aspect of the invention relates to a fresh ultra-high strength concrete comprising a dry mix according to the invention as described above for the production of an ultra high strength concrete and water.

In a preferred embodiment, the fresh ultra-high strength concrete, based on the concrete bulk density [kg / m ³ ]: 29 to 35%, preferably 31 to 33%, aggregate; 0.1 to 7%, preferably 3 to 5%, of the first filler; 0.1 to 5%, preferably 1 to 3%, of the second filler; 30 to 41%, preferably 35 to 37%, binder, 5 to 17%, preferably 9 to 12%, fiber material and 4 to 10%, preferably 6 to 9%, water.

Typically, the fresh ultra-high strength concrete comprises at least one flow agent, in particular comprising acrylic polymers, for example Dynamon NRG 1020 (Mapei), polycarboxylates, polycarboxylate ethers and polycarboxylate esters. Furthermore, the fresh ultra high strength concrete can contain at least one deaerator. Among other things, alkyl phosphates, such as triisobutyl phosphate, triethyl phosphate or tri-n-butyl phosphate, can be used as deaerators.

Another aspect of the invention relates to the use of a fresh ultra high strength concrete according to the invention as a building material. The fresh ultra-high strength concrete according to the invention is typically used for the production of concrete components, repair or maintenance of concrete structures, such as pillars, supports or beams, bridges, drainage systems or channels. The fresh ultra-high strength concrete according to the invention is additionally used as a building material for traffic routes, such as roads, walkways, tracks or airport runways.

CH 714 974 A1 The use of fresh ultra-high strength concrete for the repair and maintenance of bridges is particularly advantageous since its use does not significantly change the statics of the bridge. Typically, the UHFB according to the invention already reaches a compressive strength of over 100 MPa after two days. Furthermore, the fresh ultra high-strength concrete can harden very quickly, so that a compressive strength of at least 20 MPa is achieved after only 2 hours. This means that traffic routes, such as a motorway bridge, can be repaired quickly without the traffic having to be diverted or jammed for a long time.

In further embodiments, the fresh ultra high-strength concrete according to the invention is used for the production of precast concrete parts, for example stairs, floor or road slabs. Furthermore, the fresh ultra high-strength concrete can be used in the manufacture of wind turbines. The fresh ultra high strength concrete is typically used as shotcrete.

Another aspect of the invention relates to a method for producing an ultra high-strength concrete comprising the steps: a) providing a dry mixture according to the invention and as described above; b) adding water to the dry mixture from step a) and mixing to produce a fresh ultra-high strength concrete. The mixing time in step b) is preferably 10 to 15 minutes. Typically, the fresh ultra high-strength concrete is then used in an invention, for example via injection molding. The fresh ultra-high strength concrete obtained in step b) is then dried in step c).

In some preferred embodiments, the fresh ultra high strength concrete lithium carbonate can be added to adjust the consistency so that the ultra high strength concrete reaches a compressive strength of 20 MPa after only 2 hours.

In further embodiments, the addition of binder, lithium carbonate, deaerator and / or fiber materials takes place in step b).

In a preferred embodiment, the water and the binder are first added and mixed in step b), preferably for 10 to 15 minutes. The fiber material is then added, followed by mixing, preferably for 5 to 10 minutes. The mixing time should not last longer than 20 minutes, otherwise a very unfavorable cement matrix will form.

Typically, the fiber material is added slowly, continuously and with stirring. The fiber material is particularly preferably added only after the binder has been added and mixed.

After the use of the fresh ultra high strength concrete, for example as shotcrete or for repair, it is typically dried.

Another aspect of the invention relates to an ultra-high-strength concrete, which is obtainable by an embodiment of the method according to the invention. The UHFB according to the invention preferably has a compressive strength of at least 20 MPa after 2 hours.

In preferred embodiments, the ultra-high-strength concrete according to the fire protection regulations BSV 2105 meets group RF1 and thus does not contribute to fire.

BRIEF EXPLANATION OF THE FIGURES Aspects of the invention are explained in more detail with the aid of the following exemplary embodiments and the figures. It shows:

1 shows a sieve line analysis of a first filler according to the invention in an embodiment of the invention;

2 shows a sieve line analysis of a second filler according to the invention of a further embodiment of the invention;

3 shows a sieve line analysis of an aggregate according to the invention of a further embodiment of the invention; and

4 shows a sieve line analysis of a cement according to the invention of a further embodiment of the invention.

WAYS OF IMPLEMENTING THE INVENTION Some examples of recipes for dry mixtures according to the invention for producing an ultra-high-strength concrete and for a fresh ultra-high-strength concrete are listed below.

Example 1a: dry mix for the production of an ultra-high-strength concrete

CH 714 974 A1

component Proportion in kg comment aggregate 835 Particle size 125 to 500 μm, according to FIG. 3 First filler 120 Particle size 10 to 125 μm, according to Fig. 1 Second filler 40 Particle size 0.7 to 10 μm, according to Fig. 2 microsilica 143 Mapepiast SF (manufacturer: Mapei), particle size 0.1 pm to 5 pm Example 1b: Fresh ultra-high hardened concrete component Proportion in kg comment aggregate 835 Particle size 125 to 500 μm (Fig. 3) First filler 120 Particle size 10 to 125 μm (Fig. 1) Second filler 40 Particle size 0.7 to 10 μm (Fig. 2) microsilica 143 Mapepiast SF (manufacturer: Mapei), Particle size 0.1 to 5 μm CEM I 52.5 R (Holcim Lafarge plant cement 940 Dotternhausen), particle size 0.1 μm to 40 μm (Fig. 4) steel fiber 280 Diameter less than 0.20 mm, fiber length less than 13 mm superplasticizer 37.6 Dynamon NRG 1020 (manufacturer: Mapei) water 195

Example 2a: dry mix for producing an ultra-high-strength concrete

component Proportion in kg comment aggregate 763 Particle size 125 to 500 μm (Fig. 3) First filler 135 Particle size 10 to 125 μm (Fig. 1) Second filler 50 Particle size 0.7 to 10 μm (Fig. 2) microsilica 175 Mapepiast SF (manufacturer: Mapei), particle size 0.1 to 5 μm Example 2b: Fresh ultra-high hardened concrete component Proportion in kg comment aggregate 763 Particle size 125 to 500 μm (Fig. 3) First filler 135 Particle size 10 to 125 μm (Fig. 1) Second filler 50 Particle size 0.7 to 10 μm (Fig. 2) microsilica 175 Mapepiast SF (manufacturer: Mapei), particle size 0.1 μm to 5 μm cement 940 CEM I 52.5 R (Holcim Lafarge plant in Dotternhausen), particle size 0.1 μm to 40 μm (Fig. 4) steel fiber 280 Diameter less than 0.20 mm, fiber length less than 13 mm superplasticizer 42.3 Dynamon NRG 1020 (manufacturer: Mapei) ventilator 4.7 Triisobutyl phosphate (ENTLÜFTER-RCT GmbH)

CH 714 974 A1

component Proportion in kg comment water 201

The following procedure can be used to produce fresh ultra high-strength concrete according to Example 2a:

In a first step, the aggregate, the first and second filler, the microsilica can be weighed out and mixed for 30 seconds dry mixing time. In a further step, the cement and the water are then added during continuous mixing. After a mixing time of 10 to 15 minutes, the steel fibers are added slowly, continuously and with stirring. After a mixing time of 5 to 10 minutes, the fresh ultra high-strength concrete can be used.

In the production of the fresh ultra high-strength concrete, the mixed water is usually completely consumed, so that no communicating capillary pores can form and the water entry from the outside is negligible.

In the above examples, the aggregate, the first filler and / or the second filler has a CaCOs content of 95 to 99%.

Claims (20)

claims 1. A dry mix for producing an ultra high strength concrete comprising: aggregate with a CaCO ₃ content of at least 75%; a first filler with a grain size of 10 μm to 125 μm and a second filler with a grain size of 0.7 μm to 10 μm, the first and second filler having a CaCO ₃ content of at least 75%. 2. Dry mixture according to claim 1 comprising a binder, a fiber material, a deaerator and / or microsilica with a grain size 0.1 μm to 10 μm, preferably 0.1 μm to 5 μm. 3. Dry mixture according to one of the preceding claims, wherein the aggregate has grain sizes of 125 μm to 2 mm, preferably 125 to 500 μm. 4 to 10%, preferably 6 to 9% water. 4. Dry mixture according to one of the preceding claims, wherein the aggregate, the first filler and / or the second filler have a CaCO ₃ content of 75% to 99%, preferably 90 to 99%. 5 to 17%, preferably 9 to 12%, fiber material; and 5. Dry mixture according to one of the preceding claims, wherein the aggregate, the first filler and / or the second filler have a pyrite content of at most 0.05%, preferably of at most 0.01%. 6. Dry mixture according to one of the preceding claims, wherein the aggregate, the first filler and / or the second filler have a silicate rock content of 0.05% to 10%, preferably 0.05% to 5%. 7. Dry mixture according to one of claims 2 to 6, wherein the fiber material comprises steel fibers, carbon fibers, glass fibers, plastic fibers and / or textile fibers. 8. Dry mix according to one of claims 2 to 7, wherein the binder comprises cement. 9. Dry mixture according to claim 8, wherein the cement has grain sizes from 0.1 μm to 40 μm. 10. Dry mix according to one of claims 2 or 9, wherein the binder comprises calcium sulfoaluminate. 11. Dry mixture according to one of the preceding claims additionally comprising lithium carbonate. 12. Dry mix according to one of the preceding claims, wherein the ratio of aggregate; first filler: second filler is essentially 8.5: 1: 0.5. 13. Fresh ultra high strength concrete comprising an ultra high strength concrete composition according to any one of the preceding claims and water. 14. Fresh ultra high strength concrete according to claim 13, comprising 29 to 35%, preferably 31 to 33%, aggregate; 0.1 to 7%, preferably 3 to 5%, of the first filler 0.1 to 5%, preferably 1 to 3%, of the second filler; 30 to 41%, preferably 35 to 37%, binder; 15. Fresh ultra high strength concrete according to claim 13 or 14 additionally comprising a flow agent and / or a deaerator. 16. Use of the fresh ultra-high strength concrete according to one of claims 13 to 15 as a building material, in particular for the production, repair or maintenance of concrete components, concrete structures, bridges, traffic routes, channels, buildings and tracks. 17. A method of making ultra high strength concrete comprising the steps of: CH 714 974 A1 a) provision of a dry mixture according to one of claims 1 to 12; b) adding water to the dry mixture and optionally adding binder, lithium carbonate, deaerator and / or fiber materials; and mixing to produce a fresh ultra high strength concrete; c) drying. 18. Ultra high strength concrete obtainable by the method according to claim 17. 19. Ultra high strength concrete according to claim 18, wherein the concrete has a compressive strength of at least after 2 hours Has 20 MPa. CH 714 974 A1