CH714982B1 - Ultra high performance concrete. - Google Patents

Abstract

Dry mix for the production of an ultra-high-strength concrete, comprising: aggregate with a CaCO 3 content of at least 75%; a first filler with a particle size of 10 µm to 125 µm and a second filler with a particle size of 0.7 µm to 10 µm. The first and second filler has a CaCO 3 content of at least 75%.

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 producing 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 its production.

State of the art

[0002] In contrast to common types of concrete, ultra-high-performance concrete or ultra-high-strength concrete (UHFB) is characterized, among other things, 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 around the aggregates in the event of a crack, but is characterized by cracks passing through them.

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

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

Presentation of the invention

[0005] Despite the clear advantages in terms of stability, weight and space requirement compared to the usual types of concrete, no UHFB has yet been able to establish itself as a mass product. One reason for this is the complex production process and the relatively high cost of the starting materials, which have to be prepared, processed and stored separately.

A significant disadvantage of the known ultra-high performance concretes is the occurrence of the alkali-silica reaction. The calcium hydroxide in the cement reacts with the quartz to form various calcium silicates, such as wollastonite. The alkali-silica reaction is particularly problematic when the concrete is exposed to moisture and air, as the silicates swell when they absorb water, which can lead to cracking in the concrete. In Germany alone, the need for rehabilitation of airport runways damaged due to the alkali-silica reaction was estimated at 1.2 billion euros in 2016.

It is therefore the object of the invention to further develop the prior art in the field of ultra-high strength concretes 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 more cost-effective UHFB compared to the prior art is provided.

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

[0009] These objects are solved in a general manner by the subject matter of the independent patent claims.

[0010] Further advantageous embodiments emerge from the dependent claims and the disclosure as a whole.

In a first aspect, the invention relates to a dry mix (the so-called premix) for producing an ultra-high-strength concrete, comprising an aggregate with a CaCO3 content of at least 75%. Furthermore, the dry mixture comprises a first filler with a particle size of essentially 10 μm to 125 μm and a second filler with a particle size of essentially 0.7 μm to 10 μm. The first and second filler each have a CaCO3 content of at least 75%. It has been shown that due to the high CaCO3 content of the aggregate and the first and second filler, a particularly dense packing and a particularly strong bond between the particles in the UHFB can be achieved, which also increases its strength. This effect is additionally intensified by the use of a first and a second filler with different particle sizes, since this avoids voids and the formation of pores in the UHFB produced from the dry mixture according to the invention. It has been shown that the claimed particle size ranges of the first and second filler achieve a synergistic effect, since the first filler efficiently fills the larger voids in the packing of the aggregate and the second filler fills the smaller voids in the packing of the second filler.

The person skilled in the art understands that, as is usual in the production of concrete, the specified particle sizes are a particle size distribution and therefore small proportions of the filler may also be below the specified range. For example, the mean particle size of the second filler is preferably 2 to 6 μm. In addition, a person skilled in the art is familiar with the term aggregate, for example from the EN 12620:2018 standard.

The use of quartz sand is preferably dispensed with, as a result of which a very cost-effective and stable ultra-high performance concrete can be obtained by means of a dry mixture according to the invention.

In a further embodiment, a dry mix according to the invention for the production of an ultra-high-strength concrete additionally comprises a binder or an additive, for example cement, lime or fly ash.

In some embodiments, the dry mix for producing an ultra high performance concrete additionally comprises a fibrous material. This fiber material can be steel fibers, carbon fibers, mineral fibers, e.g. made of basalt, plastic fibers, e.g. made of polypropylene, textile fibers or glass fibers or a mixture thereof.

[0016] Typically, the dry mixture additionally comprises microsilica with a particle size of 0.1 μm to 10 μm, preferably 0.1 μm to 5 μm. Commercially available compacted microsilica is typically used. Alternatively, however, it is also possible to use uncompacted microsilica. The wear resistance and the service life of the UHFB according to the invention can be increased through the use of microsilica.

In a further embodiment, the dry mixture additionally comprises a deaerator, preferably an alkyl phosphate such as triisobutyl phosphate, triethyl phosphate or tri-n-butyl phosphate. By using a deaerator, the volume of air voids in the fresh ultra high performance concrete and ultra high performance concrete produced from the dry mix 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 CaCO3 content of 75% to 99%, preferably 90 to 99%, particularly preferably 93% to 99%. Preferably, the aggregate, first filler and/or second filler is resistant to the alkali-silica reaction (alkaline aggregate resistant). This resistance can be achieved, inter alia, 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 are 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 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 phyllosilicates such as mica, kaolinite, chlorite and swellable materials in the aggregate, the first filler and/or the second filler is less than 6%. The proportion of swellable minerals is preferably below 0.1%.

In a further embodiment, the aggregate, the first filler and/or the second filler has a silicate 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 particle sizes from 0.1 μm to 40 μm.

In a further embodiment, the binder comprises calcium sulfoaluminate or CEM I cement (Portland cement with a maximum of 5% other materials). The proportion of calcium sulfoaluminate in the binder is preferably 50 to 85%, preferably 75 to 85%.

In a preferred embodiment, the dry mix for producing a UHFB comprises lithium carbonate. By using lithium carbonate, the processing time and the consistency of the fresh ultra-high performance concrete produced from the dry mix can be regulated in terms of time. In particular, the setting of the fresh ultra-high performance concrete can be accelerated. The lithium carbonate content is preferably 0.2 to 1%, particularly preferably 0.5%, based on the weight of the binder.

In a further embodiment, the dry mix for producing a UHFB comprises at least one fruit acid, for example tartaric acid, malic acid or citric acid. These are preferably added to the dry mixture as a 20 to 50% aqueous solution. It has been shown that the processing time of the fresh ultra-high performance concrete produced from the dry mix can also be regulated by the fruit acid. In particular, this can delay the onset of setting of the fresh ultra-high performance concrete. The content of the at least one fruit acid is preferably 0.25 to 5%.

In some embodiments, the ratio of aggregate:first filler:second filler in the dry mix may be substantially 8.5:1:0.5. A particularly stable UHFB can be obtained as a result.

In a further embodiment, the dry mixture additionally comprises hard particles to protect against abrasion of the ultra-high performance concrete produced from the dry mixture. The hard particles are typically made of an abrasion-resistant material, such as corundum or silicon carbide (Lonsicar).

In some embodiments, the dry mixture can consist of aggregate with a CaCO3 content of at least 75%, 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 . Alternatively, the dry mixture can also consist of one or more of the components mentioned above, such as binders, fiber material, microsilica, deaerating agents, lithium carbonate and/or acid acids.

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

In a preferred embodiment, the fresh ultra-high performance concrete comprises, 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

[0032] In further embodiments, the fresh ultra-high performance concrete comprises, 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 and 30 to 41%, preferably 35 to 37%, binder.

[0033] In further embodiments, the fresh ultra-high performance concrete comprises, 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 and 5 to 17%, preferably 9 to 12%, fiber material and 4 to 10%, preferably 6 to 9%, water.

Typically, the fresh ultra-high performance concrete comprises at least one superplasticizer, including in particular acrylic polymers, for example Dynamon NRG 1020 (Mapei), polycarboxylates, polycarboxylate ethers and polycarboxylate esters. Furthermore, the fresh ultra-high performance concrete can contain at least one deaerator. Alkyl phosphates such as, for example, triisobutyl phosphate, triethyl phosphate or tri-n-butyl phosphate can be used as deaerators. In addition, the fresh ultra-high performance concrete can have hard particles to protect against abrasion.

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

The use of the fresh ultra-high performance 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 achieves a compressive strength of more than 100 MPa after two days. Furthermore, the fresh ultra-high performance 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 backed up for a long time.

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

A further aspect of the invention relates to a method for producing an ultra-high-strength concrete, comprising the steps: a) providing a dry mix 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 performance concrete. The mixing time in step b) is preferably 5 to 15 minutes. Typically, the fresh ultra-high performance concrete is then used in a process according to the invention, for example via injection molding. Then, in step c), the fresh ultra-high performance concrete obtained in step b) is dried. Optionally, the fresh ultra-high performance concrete can be covered to protect it from premature drying out, mechanical or chemical stress and extreme temperatures.

In a further preferred embodiment, the fresh ultra-high performance concrete is smoothed and/or coated. Here, the fresh ultra-high performance concrete is preferably coated with a curing product. The curing product protects the fresh ultra-high performance concrete from drying out due to the effects of heat and wind and thus delays the evaporation of moisture from the concrete surface, which prevents plastic shrinkage and the formation of cracks.

A polymer resin or a mixture of polymer resins is preferably used as the after-treatment product. This is preferably in the form of an aqueous emulsion. For example, Mapecure E30 (Mapei Suissa SA) or Mapacrete Film 14 (Mapei Suisse SA) can be used as after-treatment product.

In some preferred embodiments, lithium carbonate can be added to the fresh ultra-high-performance concrete to adjust the processing time, so that the ultra-high-performance concrete achieves a compressive strength of 20 MPa after just 2 hours.

In preferred embodiments, at least one fruit acid, for example malic acid, tartaric acid or citric acid, can be added to the fresh ultra-high-performance concrete to adjust the processing time. The at least one fruit acid is preferably added as a 20 to 50% aqueous solution.

In further embodiments, binders (for example calcium sulfonate), hard particles, lithium carbonate, deaerators and/or fiber materials are additionally added in step b).

In a preferred embodiment, in step b) the water and the binder are first added and mixed, preferably for 2 to 15 minutes. Thereafter, the fiber material is 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 addition of the binder and mixing has taken place. In some embodiments, the fiber materials are already contained in the dry mixture according to the invention and therefore do not have to be added in an additional step. The fiber materials can preferably be added to the dry mixture according to the invention by means of suitable fiber metering systems.

After the fresh ultra-high performance concrete has been used, for example as shotcrete or for repairs, it is typically dried.

A further aspect of the invention relates to an ultra-high-strength concrete which can be obtained 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 invention fulfills group RF1 according to the fire protection regulations BSV 2105 and thus makes no contribution to the fire.

A further aspect of the invention relates to a parts set comprising a dry mixture according to the invention as described above and hard particles. The hard particles are typically made of an abrasion-resistant material, for example corundum or silicon carbide (Lonsicar) and are preferably applied to the fresh ultra-high-performance concrete produced from the dry mix. This can typically be done by sprinkling and possibly pressing.

In a preferred embodiment, the kit of parts comprises a dry mixture according to the invention as described above and an aftertreatment product, preferably polymer resins, which are typically present as an aqueous emulsion. Optionally, the parts set can also include hard particles.

Brief explanation of the figures

Aspects of the invention are explained in more detail on the basis of the following exemplary embodiments and the figures. 1 shows a grading curve analysis of a first filler according to the invention of an embodiment of the invention; 2 shows a grading curve analysis of a second filler according to the invention of a further embodiment of the invention; 3 shows a grading curve analysis of an aggregate according to the invention of a further embodiment of the invention; and FIG. 4 shows a grading curve analysis of a cement according to the invention of a further embodiment of the invention.

Ways to carry out the invention

Some examples of formulations for dry mixes 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 performance concrete

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 Mapeplast SF (manufacturer: Mapei), particle size 0.1 µm to 5 µm

Example 1b: Fresh ultra high performance concrete

Aggregate 835, particle size 125 to 500 μm (Figure 3) First filler 120, particle size 10 to 125 μm (Figure 1) Second filler 40, particle size 0.7 to 10 μm (Figure 2) Microsilica 143 Mapeplast SF (manufacturer: Mapei), particle size 0.1 µm to 5 µm cement 940 CEM I 52.5 R (LafargeHolcim Dotternhausen plant), particle size 0.1 µm to 40 µm (Figure 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 the production of an ultra high performance concrete

Aggregate 763, particle size 125 to 500 μm (Figure 3) First filler 135, particle size 10 to 125 μm (Figure 1) Second filler 50, particle size 0.7 to 10 μm (Figure 2) Microsilica 175 Mapeplast SF (manufacturer: Mapei), particle size 0.1 µm to 5 µm

Example 2b: Fresh ultra high performance concrete

Aggregate 763, particle size 125 to 500 μm (Figure 3) First filler 135, particle size 10 to 125 μm (Figure 1) Second filler 50, particle size 0.7 to 10 μm (Figure 2) Microsilica 175 Mapeplast SF (manufacturer: Mapei), particle size 0.1 µm to 5 µm cement 940 CEM I 52.5 R (LafargeHolcim Dotternhausen plant), particle size 0.1 µm to 40 µm (Figure 4) steel fiber 280 diameter less than 0.20 mm, fiber length less than 13 mm superplasticizer 42.3 Dynamon NRG 1020 (manufacturer: Mapei) deaerator 4.7 triisobutyl phosphate (AIR BREAKER - RCT GmbH) Water 201

To produce a fresh ultra-high performance concrete according to example 2a, the following procedure can be followed: In a first step, the aggregate, the first and second filler, the microsilica can be weighed in and mixed for a dry mixing time of 30 seconds. In a further step, the cement and the water are then added during continuous mixing. After a mixing time of 5 to 15 minutes, the steel fibers are added slowly, continuously and with stirring. Alternatively, the fibers may already be included in the dry blend as described above. After a mixing time of 5 to 10 minutes, the freshly produced ultra high performance concrete can be used.

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

In the above examples, the aggregate, the first filler and/or the second filler has a CaCO3 content of 95 to 99%.

Claims (21)

1. Dry mix for the production of an ultra high performance concrete comprising: aggregate with a CaCO3 content of at least 75%; a first filler with a particle size of 10 µm to 125 µm and a second filler with a particle size of 0.7 µm to 10 µm, the first and second filler having a CaCO3 content of at least 75%. 2. Dry mix according to claim 1 comprising a binder and/or a fiber material and/or a deaerator and/or microsilica, the microsilica having a grain size of 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 a particle size of 125 μm to 2 mm, preferably 125 to 500 μm. 4. Dry mixture according to one of the preceding claims, wherein the aggregate, the first filler and/or the second filler have a CaCO3 content of 75% to 99%, preferably 90 to 99%. 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 at most 0.01%. 6. Dry mix according to one of the preceding claims, wherein the aggregate, the first filler and/or the second filler have a silicate content of 0.05% to 10%, preferably 0.05% to 5%. 7. Dry mix according to any 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 any one of claims 2 to 7, wherein the binder comprises cement, preferably calcium sulfoaluminate or CEM I cement. 9. Dry mix according to claim 8, wherein the cement has grain sizes of 0.1 microns to 40 microns. 10. Dry mix according to one of the preceding claims additionally comprising lithium carbonate and/or at least one fruit acid. 11. Dry mixture according to one of the preceding claims, wherein the ratio of aggregate: first filler: second filler is essentially 8.5:1. is 0.5. 12. Dry mixture according to one of the preceding claims, wherein the dry mixture additionally comprises hard particles. 13. Fresh ultra high performance concrete comprising a dry mix according to any one of the preceding claims, a binder and water. 14. Fresh ultra high performance 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; 5 to 17%, preferably 9 to 12%, fiber material; and 4 to 10%, preferably 6 to 9% water. 15. Fresh ultra high performance concrete according to claim 13 or 14 additionally comprising hard particles, a superplasticizer and/or a deaerator. 16. Use of the fresh ultra-high performance concrete according to any 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, canals, buildings and tracks. 17. A method for producing an ultra-high performance concrete, comprising the steps: a) providing a dry mix according to any one of claims 1 to 12; b) addition of water to the dry mixture and addition of binder and optional addition of lithium carbonate, at least one fruit acid, hard particles, deaerator and/or fiber materials; and mixing to produce a fresh ultra high performance concrete; c) drying. 18. The method according to claim 17, wherein the fresh ultra-high performance concrete produced in step b) is smoothed and/or coated with an after-treatment product. 19. Ultra high performance concrete obtained by the method according to any one of claims 17 or 18. 20. Ultra high performance concrete according to claim 19, wherein the concrete has a compressive strength of at least 20 MPa after 2 hours. 21. Parts set comprising a dry mixture according to any one of claims 1 to 12 and hard particles and/or an aftertreatment product.