DE102017127594B4 - Lossless transfer of micro / nano-structured surfaces to UHPC, concrete and other cementitious materials for the creation of diffractive optical components - Google Patents

Abstract

It is proposed an optical element comprising a plurality of regularly arranged surfaces made of concrete, wherein the edge lengths of the regularly arranged surfaces of concrete in a range of 10 nm to 50 microns.

Description

The invention is in the field of optical functional structures, in particular of blaze gratings, laminar gratings and diffractive optical elements and relates to their production from concrete.

Depending on the type, optical functional structures are produced in many different ways. Blaze grids are typically manufactured at great expense by photolithographic techniques or by micromechanical processes such as scribing, embossing or planing with diamond tools. However, these methods typically require a high equipment cost and long production times and are therefore costly.

The publication DE 20 2009 016 496 U1 describes decorative concrete elements with defined arranged translucent built-in parts. The publication DE 10 2008 027 799 A1 describes light-conducting stones, plates and stones with layers of substantially parallel light-conducting fibers. The publication WO 2008/031610 A1 describes a module with light-conducting fibers. On the other hand, by means of fine structuring of a concrete surface, structures in the micrometer and submicrometer range can be produced within a few hours, for example within 24 hours.

Against this background, the development of concrete technology is proposed for the cost-effective production of load-stable gratings and diffraction structures on the way of the molding of a formwork facing. In particular, an optical element according to claim 1, a method for producing such according to claim 10, a concrete molding according to claim 12 and the use of a material according to claim 16 are proposed. Other embodiments, modifications and improvements will become apparent from the following description and the appended claims.

According to a first embodiment, an optical element is proposed comprising a plurality of regularly arranged surfaces of concrete, wherein at least one edge length of the regularly arranged surfaces of concrete is in a range of 10 nm to 50 microns.

Advantageously, optical elements made of concrete, in particular diffractive optical elements, open up numerous fields of application for concrete technology. Such optical elements are easy to produce.

According to another embodiment, the proposed optical element is selected from a diffractive optical element, a sawtooth grating (Blaze grating) and an echelette grating. The mentioned grids can be designed both as a flat grating and as a concave grating.

Advantageously, these gratings can be used both in research, for example in radiation physics, but can also be used for targeted large-area modification of exposed concrete.

According to a further embodiment, a surface of the designated areas at least in sections on a roughness in the nanometer scale.

In particular, a roughness may be selected in the range of 10nm-250nm; in the range 50nm-200nm; or in the range 75nm to 150nm. Advantages of these roughness ranges relate to the optical quality of the gratings which can be produced in this way, for example the formation of pixel areas (see below).

According to another embodiment, the concrete used to form the optical element is a UHPC concrete.

Advantageously, it is precisely with UHPC concretes that it is possible to realize low roughness values of the resulting concrete surfaces.

According to a further embodiment, the optical element is set up for shaping and / or manipulation of coherent light in the energy range of the X-ray radiation. This coherent light, d. H. The X-ray radiation may have been generated for example in a free electron laser (FEL) or an electron storage ring.

Especially in particle physics there is a need for stable optically diffractive elements. From a die having the negative of the desired structure, a plurality of identical structures can be inexpensively molded within a relatively short time.

According to a further embodiment, the optical element is set up to trigger a color impression on an observer when exposed to white light.

This results in numerous applications in the field of architecture, for example, for a coloring and / or imaging.

According to a further embodiment, the optical element is set up to reflect IR radiation.

Advantageously, such IR radiation can be derived or for heating, for example of water, directed to be radiated from the corresponding surface.

According to a further embodiment, the optical element is selected under a grating, under a hologram, under an optical waveguide and / or under a photonic crystal.

These optical elements provide the applications described below.

According to a further embodiment, the proposed optical element is part of a concrete component and serves to identify the origin and / or the determination of the concrete component.

For example, it can serve as a security feature.

• - Bereitstellen eines Frischbetons, umfassend:
  • o einen Zement, beispielsweise gemäß DIN EN 197-1 ;
  • o eine Gesteinskörnung natürlichen oder künstlichen Ursprungs, wobei eine maximale Korngröße der Gesteinskörnung bevorzugt 2 mm beträgt;
  • o ein Gesteinsmehl natürlichen oder künstlichen Ursprungs oder einen anderen als Betonzusatzstoff bekannten oder zugelassenen Stoff, ausgewählt unter einer Flugasche (z.B. eines Kohlekraftwerkes), einem Trass, einer Mikrosilica oder einem Silicastaub, einem Hüttensandmehl oder einem gemahlenen Reststoff einer Erzverhüttung;
  • o Wasser, sodass ein Wasserzementwert in dem Frischbeton zwischen 0,15 bis 0,60; insbesondere zwischen 0,25 bis 0,35 einstellbar ist;
• - Bereitstellen einer nanostrukturierten Schalhaut, wobei die Schalhaut ein Negativ der gewünschten optisch aktiven Struktur aufweist;
• - In Kontakt-Bringen der Schalhaut mit dem Frischbeton;
• - Abbinden des Frischbetons;
• - Ausschalen und/oder Entformen des optischen Elements.

According to a further embodiment, a method for producing an optical element is proposed which comprises the following steps:

• Providing a fresh concrete, comprising:
  • o a cement, for example according to DIN EN 197-1 ;
  • o an aggregate of natural or artificial origin, a maximum grain size of the aggregate preferably being 2 mm;
  • o a rock meal of natural or artificial origin or another substance known or authorized as a concrete additive chosen from a fly ash (eg coal-fired power plant), a trass, a microsilica or a silica fume, a granulated blastfurnace or a ground residue of an ore smelting;
  • o water, so that a water cement value in the fresh concrete between 0.15 to 0.60; in particular between 0.25 to 0.35 is adjustable;
• - Providing a nanostructured formwork, wherein the formwork skin has a negative of the desired optically active structure;
• - bringing the formwork into contact with the fresh concrete;
• - setting the fresh concrete;
• - Stripping and / or removal of the optical element.

Advantageously, the process is robust and the raw materials used are available at low cost.

According to a further embodiment, the optical element is part of a concrete molding.

According to a further embodiment, a concrete part is proposed, which comprises at least one arranged on a surface of the concrete molding optical element according to at least one of the embodiments described above.

Advantageously, engineering structures comprising large areas can be assembled from individual concrete components. The optical elements of the individual components can jointly fulfill a function in their interaction. You can create a specific color or gradient without the need for expensive pigments. While, for example, the large-scale and coordinated application of pigments to produce a large area of a certain spectral iridescent spanning color impression is very complicated and expensive, on the simple use of surface structures on the surfaces of adjacent concrete components such a rainbow-like color distribution can be easily accomplished without z.T. to have to resort to very expensive pigments. Likewise, for example, a hologram can attest the authenticity of the origin of a concrete component and at least complicate a forgery of the concrete component.

According to a further embodiment, it is proposed to use a multiplicity of optical elements arranged on the surface of the component as pixels of an image composed of pixels. In other words, a visual impression when viewing the concrete surface in a viewer can give a picture impression. The individual optical elements or groups of optical elements need not necessarily be perceived as separate pixels.

According to a further embodiment, the optical element is used for directed optical waveguide.

Advantageously, incident sunlight can be guided. For example, IR components of incident sunlight can be used purposefully for heating a water tank or a water-bearing pipe.

According to a further embodiment, the optical element reflects an IR radiation.

Advantageously, such a heating of a building part can be reduced. The energy required for air conditioning (cooling) of premises of the building can be reduced.

According to a further embodiment, a material selected from a UHPC, a concrete, a blast furnace slag, is proposed, a blast-furnace slag meal, a quartz flour, a marble meal, a titanium dioxide, a lime-sandstone, a fly ash, a trass, a microsilica, a silica fume, a ground residue of an ore smelting and / or a metal powder for producing an optical element according to the above-mentioned embodiments.

The materials mentioned are available at low cost, so that a plurality of corresponding optical elements can be successively fabricated on a formwork skin once present, provided with the negative of an optical functional structure.

The above-described embodiments may be arbitrarily combined with each other.

Technological background

Concrete basically consists of cement (binder), water and aggregate. Ultra-High Performance Concrete (UHPC), is an ultra-high-strength concrete, which is characterized by a high structural density. This is, inter alia, by an optimizable packing of fines content (cement, usually Portland cement but also Portlandkompositzement after DIN EN 197-1 , and usually rock flour and possibly reactive additives) <0, 125mm achieved.

The invention described here makes use of this approach and shows the possibility that with decreasing particle size of the fine fraction a higher density of the mixture can be achieved (grading curve of the fine particles / sieving line of the aggregate), which allows structures in the μm and nm ranges produce. Fillers and reactants (such as blast furnace slag, blast furnace slags, quartz flours, titanium dioxide, marble flours, lime-sandstones, etc.) play an important role in achieving the desired amount of fines.

In addition, the gloss level of the concrete surface can be positively influenced (from dull to matt to high gloss) by setting the recipe. Quartz sands (up to preferably 2 mm grain size) as aggregate show good suitability for the creation of reflective surfaces. Further, other types of rocks may be used (e.g., basalt, granodiorite, etc.).

In addition, high performance flow agents (e.g., BASF Master Glenium 454, Grace AdvaFlow, etc.) can be added to the fresh concrete to achieve the desired fluidity while reducing water requirements. Similarly, shrinkage reducers (SRA), e.g. Sika Control, etc., and their liquefying and stabilizing properties are used in fresh concrete. The fresh concrete obtained is the addition of the above auxiliaries to a self-compacting mass.

• - einen Zement, beispielsweise gemäß DIN EN 197-1 ;
• - eine Gesteinskörnung natürlichen oder künstlichen Ursprungs, wobei eine maximale Korngröße der Gesteinskörnung bevorzugt 2 mm beträgt;
• - ein Gesteinsmehl natürlichen oder künstlichen Ursprungs oder einen anderen als Betonzusatzstoff bekannten oder zugelassenen Stoff, ausgewählt unter einer Flugasche (z.B. eines Kohlekraftwerkes), einem Trass, einer Mikrosilica oder einem Silicastaub, einem Hüttensandmehl oder einem gemahlenen Reststoff einer Erzverhüttung;
• - Wasser, sodass ein Wasserzementwert in dem Frischbeton zwischen 0,15 bis 0,60; insbesondere zwischen 0,25 bis 0,35 einstellbar ist.

It is proposed that the fresh concrete used in the process is selected from a concrete mixture comprising:

• a cement, for example according to DIN EN 197-1 ;
• - an aggregate of natural or artificial origin, with a maximum grain size of the aggregate preferably being 2 mm;
• - a powdered rock of natural or artificial origin or any substance known or authorized as a concrete additive, selected from fly ash (eg coal-fired power plant), trass, microsilica or silica fume, blastfurnace slag or milled scrap of an ore smelting plant;
• - Water, so that a water cement value in the fresh concrete between 0.15 to 0.60; in particular between 0.25 to 0.35 is adjustable.

Optionally, the concrete mix for the fresh concrete may comprise a concrete admixture.

Suitable concrete admixtures are used to control properties of the fresh concrete and / or the hardened concrete available from the fresh concrete. Examples of influenceable values concern reduced water demand (water requirement), liquefaction, stabilization, air entrainment, acceleration or retardation of cement hydration (solidification or hardening), the density of the concrete obtained (especially impermeability to water), shrinkage or swelling.

Advantages of this embodiment relate above all to the strength of the concrete obtained, or of the high-performance concrete (UHPC).

Furthermore, it has proven to be advantageous to counteract any shrinkage processes of the solidified UHPC with SRA.

The fresh UHPC mixture adapts to the surface structure of the shuttering material down to the nanometer range, which remains on its surface after solidification / hardening of the UHPC as a "negative". So can be obtained with a finely tuned Sieblinie the starting material in conjunction with PCE flow agents (polycarboxylate ethers) and equipped with the desired surface structure formwork material and a appropriate process control during filling and setting of the UHPC (venting or compaction and a proper post-treatment, which prevents excessive evaporation of the concrete feed water, eg by covering with a plastic foil) down to the nanometer scale detailed copy of the formwork in the concrete too produce.

Furthermore, according to the invention, the surface roughness is transferred from the formwork to the material during the solidification or hardening process.

To achieve a non-porous surface, the solidification of the fresh UHPC in the structured formwork can be carried out under vacuum in order to additionally avoid any air pockets.

The consideration of the above-mentioned principles as well as their coordinated application make it possible to produce surface structures on concrete by molding, which allow their application as diffractive optical elements.

The use of very elastic (ie reversibly highly stretchable) shell skins with intrinsically low surface energy (eg PDMS = polydimethylsiloxane) allows after curing a fresh concrete (UHPC or other cementitious materials) demolding of a negative of the desired optically active structure, for example, a complex freeform undercuts. This adaptation of the nanostructured formwork allows three-dimensional surface structuring of UHPC and other cementitious materials.

applications

The applications described below are based on diffraction phenomena.

If e.g. a structure in PDMS, consisting of fields with trenches or holes of different dimensions from nm to mm, used as shuttering skin, gives a negative copy of the structure on the concrete surface using the above formulation and transfer (see above).

If you now judge for example a commercial laser on the concrete surface, the laser beam is reflected on the surface structures and diffracted. This results in the following separately discussed applications:

Optical grids (diffractive optical elements) made of UHPC, concrete and other cementitious materials

If you use the o.g. Findings, it is e.g. able u.a. optical gratings (laminar grating and blaze grating) for use on FEL (Free Electron Laser) sources. Here, the grids are subject to high temperature loads during shelling with short-wave, high-intensity radiation and must be dimensionally stable. With an additional coating of the surface or also admixture of suitable metallic nanoparticles, the efficiency of these grids can be further optimized and increased.

By this method one is able to produce diffractive optical elements (DOE) in UHPC. These diffractive optical elements can be used if other replications can not withstand the energetic load. Replication with UHPC is not as costly and consistent as replication with plastics or hybrid polymers. With UHPC molding, structure sizes down to the nanometer range can be realized. Distinguishing for the UHPC is its durability. In addition, the use of this material is characterized by a time-saving production compared to the silicon technology, since once generated grid can be replicated several times by molding with UHPC.

The utilization of the moldability of a corresponding polymer formwork skin allows a full-surface, homogeneous transfer to UHPC, concrete and other cementitious materials of structures, which are exemplary in the 1a) to 1d) are shown. The resulting concrete surfaces reflect and diffract light, depending on the current structural widths.

The 1 shows corresponding structures schematically. Here, p - period, the period p is usually given in lines per millimeter. Preferred periods herein include values from 50 to 10,000 mm ^-1 . This corresponds to structure sizes of p = 0.1-20 μm at a height (h): 0.1 nm to 50 μm, the angle α being 0 <α <90 °.

Due to the fact that the feature widths approximately correspond to the wavelength of the incident light, light waves reflected at neighboring structures receive a path difference d = g (sin (θ) -sin (θ _i )) (g: lattice constant, θ: viewing angle and θ _i : angle of incidence), which leads to interference phenomena, in particular to constructive interference in the far field at the points where the path difference is an integer multiple of the wavelength.

These diffraction and interference effects have never before been described on surfaces of cementitious materials because most of the light was not diffracted, but diffusely reflected / scattered or absorbed. The high dimensional accuracy on the concrete surface and very low roughness in the transmission of the lattice structures make this possible. Only in this way can the multispectral light beams be split up by wavelength and then their respective intensity can be recorded by a detector.

Light-conducting or coloring micro- and nanostructures made of UHPC, concretes and other cement-bound materials

Other applications of such nanoscale or microscale structural surfaces are in the field of architecture, civil engineering, and environmental engineering. Here concrete surfaces with structures for forwarding z. B. visible light and IR radiation or be equipped with color effects. These are usually periodic structures (eg photonic crystals), consisting of transparent to the respective application wavelength range transparent layers with refractive index difference to the surrounding material and / or surrounding air, in their lateral structure dimensions and structure heights dimensions of a few microns to in the nanometer range. If these structures are combined with waveguide structures, the radiation can be selectively directed to the concrete surface and used elsewhere for conversion into heat or other energy.

• 2: Photonischer Kristall mit Wellenleiter, Strukturgrößen der Löcher 10nm bis zu einigen µm. Symmetrische Anordnung , mit Abständen von 50nm bis einigen µm
• 3: Photonischer Kristall mit Wellenleiter, (Säulen) Durchmesser von wenigen 10nm bis einigen 10µm. Abstände einige 100nm bis einige 100µm, Höhe bis zu einigen 10 µm.

The 2 and 3 show schematically different photonic crystals.

• 2 : Photonic crystal with waveguide, structure sizes of holes 10nm up to several μm. Symmetrical arrangement, with distances from 50nm to several μm
• 3 : Photonic crystal with waveguide, (pillars) diameter from a few 10nm to several 10μm. Distances some 100nm to several 100μm, height up to several 10 μm.

UHPC IR-reflecting surfaces, concretes and other cementitious materials

Furthermore, the degree of IR reflection of the UHPC surface can be enhanced to dissipate and redirect and otherwise utilize sunlight (here heat). In this way, equipped roof areas, facade areas or other facilities, could be cooled without further energy needs. In addition, the heat radiation can be productively produced by directional reflection, e.g. be used for hot water.

The ability to reflect IR radiation through the UHPC surface can be increased by adding additives to the concrete, e.g. Titanium dioxide, IR reflective polymer particles, corrosion resistant metal particles, or corrosion sensitive coated metal particles. In addition, the UHPC effect pigments can be added to increase the degree of reflection.

UHPC, concrete, and other cementitious materials for directional reflection of one or more wavelengths of the visible region, coloring microstructures or nanostructures

Coloring micro or nanostructures allow diffraction and interference of incident light as described above. In this case, however, the structures are designed such that incident light is specifically directed to a viewing point dependent on the wavelength, so that when viewing the surface from this point several specific colors are reproduced on the surface, thus producing a freely selectable true-color image.

This can be achieved, for example, by composing an image on the surface of pixels. Each pixel in turn consists of a few reflection grids, each reflecting a specific spectral color on the viewing point, eg three grids with the colors red, green and blue. The lattice constant of such a lattice is g = | λ m / (sin (θ _i ) + sin (θ)) |, with the desired wavelength λ, the diffraction order m, the angle of incidence θ _i at the location of the pixel and the angle θ between the solder to the surface and the place of the viewer. The intensities of the light of these spectral colors, which reach the observer, are adjusted specifically and independently of one another by the quality of the gratings (eg deliberately introduced roughness) or the area fraction that the grating occupies in the pixel. By specifically set relative and absolute intensities of the individual spectral colors selected pixels can be generated, which cause the viewer a specific color and brightness perception. An image composed of such pixels generated when illuminated by an external white light source, such as the sun or a spotlight, the viewer the impression of a bright real-color image, comparable to a display, TV or the like, only that this exclusively by the UHPC or Concrete surface and an external white light source is performed.

Applications for nanostructured UHPC surfaces can be found in the artistic sector (sculptures, etc., with structural, iridescent coloring by two- or three-dimensional periodic surface structures), the energy sector (parabolic surfaces for reflecting sunlight), the field of traffic safety ( warning reflector surfaces, white light holograms, etc.) as well as in many other areas of daily life.

UHPC or concrete surfaces, as well as surfaces of other cement-bound materials as hologram carriers (for certification purposes, among others)

A UHPC, concrete or other cement-bonded material that is specifically structured in the μm and nm range can be used as a hologram carrier. Diffractive optical elements (DOEs) are also used here. The structure sizes are here also in the range of a few microns to a few hundred nm. The product here is a hologram, which in turn u.a. Application in the field of architecture and traffic safety can be found. These holograms can also be used for product safety purposes. Holograms are virtually tamper-proof and can also be used to document, for example, the origin of components.

1. 1. Verwendung des Werkstoffes UHPC, Beton und sonstiger zementgebundener Werkstoffe zur Erstellung optischer Komponenten;
2. 2. Nutzung des fein gesiebten bzw. im Feinkornbereich abgestimmten UHPC zur flächendeckenden, homogenen Abformung von nano- bzw. mikroskaligen Oberflächen;
3. 3. Blazegitter aus UHPC, Beton, zementgebundenen Werkstoffen als DOE zur physikalischen Anwendung u.a. an FEL;
4. 4. Laminare Gitter aus UHPC, Beton, zementgebundenen Werkstoffen als DOE zur physikalischen Anwendung u.a. an FEL;
5. 5. Diffraktive optische Elemente aus UHPC, Beton und anderen zementgebundenen Werkstoffen;
6. 6. Herstellung von optischen Oberflächen an Gebäuden zur Unterstützung der Klimatechnik;
7. 7. Herstellung von optischen Strukturen zur Erzeugung eines vorbestimmten Farbverhaltens durch Nutzung von (nanoskaligen/mikroskaligen) DOE oder gerichtet diffusstreuenden Strukturen aus UHPC, Betonen und sonstigen zementgebundenen Werkstoffen;
8. 8. Nutzung von nano- oder mikrostrukturierten sowie durch Rezeptur voreingestellten UHPC-, Beton- und sonstigen zementgebundenen Werkstoffoberflächen zur gerichteten Weiterleitung elektromagnetischer Strahlung;
9. 9. Nutzung der (nanoskaligen) Betonoberflächen in der Strahlenphysik als diffraktive Bauelemente;
10. 10. Nutzung der (nanoskaligen) Betonoberflächen in der Verkehrssicherheit (z.B. durch Übertragung von Hologrammen);
11. 11. DOEs aus UHPC, Betonen und sonstigen zementgebundenen Werkstoffen zur Lichtbeugung.

The essence of the invention described here can be summarized under the following points:

1. 1. Use of the material UHPC, concrete and other cementitious materials for the production of optical components;
2. 2. Utilization of the finely sieved UHPC, which has been fine-grained, for the comprehensive, homogeneous impression of nano- or micro-scale surfaces;
3. 3. Blaze grille made of UHPC, concrete, cement-bound materials as DOE for physical application, inter alia to FEL;
4. 4. Laminar lattices made of UHPC, concrete, cement-bound materials as DOE for physical application, inter alia, to FEL;
5. 5. Diffractive optical elements made of UHPC, concrete and other cementitious materials;
6. 6. Production of optical surfaces on buildings in support of air conditioning technology;
7. 7. Production of optical structures to produce a predetermined color behavior by use of (nanoscale / microscale) DOE or directed diffusive structures of UHPC, concretes and other cementitious materials;
8. 8. Use of nano- or microstructured as well as pre-adjusted UHPC, concrete and other cement-bonded material surfaces for directional transmission of electromagnetic radiation;
9. 9. Use of (nanoscale) concrete surfaces in radiation physics as diffractive components;
10. 10. use of (nanoscale) concrete surfaces in traffic safety (eg by transfer of holograms);
11. 11. DOEs made of UHPC, concretes and other cementitious materials for light diffraction.

While specific embodiments have been illustrated and described herein, it is within the scope of the present invention to properly modify the illustrated embodiments without departing from the scope of the present invention. The following claims are a first, non-binding attempt to broadly define the invention.

Claims (17)

An optical element comprising a plurality of regularly arranged surfaces of concrete, wherein an edge length of the regularly arranged surfaces of concrete is in a range of 10 nm to 50 microns. Optical element after Claim 1 wherein the optical element is selected from a diffractive optical element, a laminar grating, an echelette grating, a sawtooth grating or a blaze grating, and / or a sine grating, said gratings being in the form of a planitter or a concave grating. Optical element according to one of the preceding claims, wherein a surface of the surfaces at least partially has a roughness in the range 10 nm to 50 microns. An optical element according to any one of the preceding claims, wherein the concrete is a UHPC concrete. Optical element according to one of the preceding claims, wherein the optical element is adapted for shaping and / or manipulation of coherent light in the energy range of an X-radiation. An optical element according to any one of the preceding claims, wherein the optical element is arranged when exposed to white light to trigger a color impression on a viewer. An optical element according to any one of the preceding claims, wherein the optical element is arranged to reflect IR radiation. Optical element according to one of the preceding claims, wherein the optical element is selected under a grid, under a hologram, under an optical waveguide and / or under a photonic crystal. Optical element according to one of the preceding claims, wherein the optical element is part of a concrete component and is used to identify a source and / or identification of a determination of the concrete component. A process for producing an optical element according to any one of the preceding Claims 1 to 9 comprising: providing a fresh concrete comprising: a cement; o an aggregate of natural or artificial origin, with a maximum aggregate grain size of 2 mm; o a rock meal of natural or artificial origin or another substance known or authorized as a concrete additive chosen from fly ash, a trass, a microsilica or a silica fume, a granulated blastfurnace or a ground residue of an ore smelting; o water, so that a water cement value in the fresh concrete between 0.15 to 0.60 is adjustable; - Providing a nanostructured formwork, wherein the formwork skin has a negative of the optical element; - bringing the formwork into contact with the fresh concrete; - setting the fresh concrete; - Stripping and / or removal of the optical element. Method according to Claim 10 , wherein the provided nanostructured formwork skin is elastic, so that the nanostructured formwork skin after setting of the fresh concrete allows stripping and / or demolding a complex freeform comprising undercuts. Method according to Claim 10 or 11 , wherein the optical element is part of a concrete molding. Concrete molding comprising at least one arranged on a surface of the concrete molding optical element according to at least one of Claims 1 to 9 , Concrete molding after Claim 13 wherein a plurality of optical elements disposed on the surface of the device are pixels of an image composed of pixels and / or give pixels. Concrete molding after Claim 13 or 14 , wherein the optical element is for directed optical waveguide. Concrete molding according to one of Claims 13 to 15 wherein the optical element reflects an IR radiation. Use of a material selected from a UHPC, a concrete, a blast furnace slag, a granulated blastfurnace, a quartz flour, a marble flour, a titanium dioxide, a lime sandstone, a fly ash, a trass, a microsilica, a silica fume, a ground residue of an ore smelting and / or a Metal powder for creating an optical element according to one of Claims 1 to 9 ,

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