Cementitious binders for geopolymers, geopolymers, and their uses

Abstract

The present invention relates to a binder for geopolymers comprising: a) at least 30% by weight of a mixture of at least two chemically distinct aluminosilicates; b) at least 20% by weight of ordinary Portland cement; and c) 8-20% by weight of calcium sulfoaluminate cement or a mixture of calcium aluminate cement and a calcium sulfate source, wherein the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate in the mixture is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.6 and 1.1. The present invention also relates to geopolymers employing such binders and their use in various construction methods.

Description

Technical Field

[0001] The present invention relates to a binder for geopolymers, comprising at least two chemically different aluminosilicates, Portland cement, calcium sulfoaluminate cement or calcium aluminate cement, and a calcium sulfate source. The present invention also relates to geopolymers using such binders and their use in various processes.

Background Art

[0002] Geopolymers are known as alternatives to Portland cement-based building materials. The term "geopolymer" was first used by Joseph Davidovits, and the respective materials were proposed as early as 1981 (see, for example, European Patent No. 0026687 assigned to J. Davidovits and CORDIS). According to this, a binder is produced by reacting an alkaline silicate solution with silicon and aluminum in a raw material of geological origin or in a by-product material such as fly ash. Since the chemical reaction that occurs is a polymerization process, the term "geopolymer" is used for these binders. Subsequently, geopolymers generally consist of an aluminosilicate component and an alkali metal silicate component that react with each other in a geopolymerization reaction. Examples of the aluminosilicate component used include fly ash, slag, and metakaolin.

[0003] Geopolymers are considered environmentally friendly building materials because they produce far less CO2 in the production of their starting materials than the production of Portland cement.

[0004] Geopolymer compositions and, in particular, geopolymer binders are described in many publications. For example, US Patent Application Publication No. 2011 / 0271876 (S. Alter et al.) discloses a geopolymer composition based on a mixture of blast furnace slag and bauxite, alumina slag, or tailings and activated by an alkali silicate.

[0005] Geopolymers can exhibit rapid setting and hardening characteristics and can have high compressive strength in the hardened state. Geopolymers are also reported to have good resistance to chemical attack (see, for example, "Resistance of geopolymer mortar to acid and chloride attacks" by H. J. Zhuang et al. in Procedia Engineering, 2017, Vol 210, p. 126 - 131).

[0006] However, geopolymers are also reported to have low adhesion to materials such as aggregates or steel reinforcements. Geopolymers also often exhibit large shrinkage compared to Portland cement - based building materials. For this reason, the development of low - shrinkage geopolymer compositions such as those disclosed in International Publication No. 2013 / 163009 pamphlet (US Gypsum Company) has been carried out. This International Publication No. 2013 / 163009 pamphlet discloses a geopolymer composition containing a thermally activated aluminosilicate mineral, calcium sulfoaluminate cement, and a calcium sulfate source as a binder activated with an alkali metal salt and / or an alkali metal base. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] There is still a need for compositions that combine some of the advantages of geopolymers, such as high resistance to chemical attack, with some of the advantages of Portland cement-based binders, such as low shrinkage. Accordingly, the present invention proposes a novel cementitious binder for geopolymers and a geopolymer to address this need.

Means for Solving the Problems

[0008] One of the objects of the present invention is to provide a cementitious binder for geopolymers. Another object of the present invention is to provide a geopolymer composition that utilizes such a cementitious binder. In particular, the cementitious binder for geopolymers, and thus the geopolymer compositions using them, should exhibit one or more of the following characteristics: (i) Low autogenous shrinkage or chemical shrinkage during hardening, (ii) High compressive strength after hardening, (iii) High resistance to chemical attack, particularly acid attack, sulfate attack, chloride attack, and / or salt-water attack in the hardened state, (iv) High freeze-thaw resistance in the hardened state.

[0009] Surprisingly, it has been found that a combination of Portland cement, at least two chemically different aluminosilicates, and calcium sulfoaluminate cement or a mixture of calcium aluminate cement and calcium sulfate is a suitable cementitious binder for geopolymers that exhibits such advantages.

[0010] In particular, it has been found that a combination of at least two chemically different aluminosilicates and Portland cement provides improved resistance of the hardened composition to chemical attack, particularly acid attack. A combination of two chemically different aluminosilicates and Portland cement provided higher resistance to chemical attack than the use of each aluminosilicate alone.

[0011] Also surprisingly, it has been found that the resistance to chemical attack and the shrinkage behavior are optimized by further using a mixture of calcium sulfoaluminate and / or calcium aluminate and a calcium sulfate source in a specific weight ratio.

[0012] Accordingly, the object of the present invention is solved by the cementitious binder for the geopolimer composition claimed in claim 1.

[0013] Other aspects of the invention are the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

DETAILED DESCRIPTION OF THE INVENTION

[0014] In a first aspect, the present invention is a cementitious binder for geopolymers, where (in each case, based on the total dry weight of the cementitious binder), a) a mixture of at least two chemically different aluminosilicates of 30% by weight or more, b) ordinary Portland cement of 20% by weight or more, c) a mixture of calcium sulfoaluminate cement or calcium aluminate cement and a calcium sulfate source of 8 - 20% by weight, wherein in the mixture, the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate is between 0.08 - 1.5, preferably 0.3 - 1.1, more preferably 0.6 - 1.1, relates to a cementitious binder containing the same.

[0015] The aluminosilicate in this situation is a pozzolanic and / or latent hydraulic material having aluminosilicate as a constituent. The chemical composition of the aluminosilicate can be measured by XRF as described in the standard EN 196-2:2013. The aluminosilicate of the present invention, as measured by XRF analysis, mainly consists of silica (SiO2, or "S" in cement notation), alumina (Al2O3, or "A" in cement chemical notation), calcium oxide (CaO, or "C" in cement chemical notation), iron oxide (Fe2O3, or "F" in cement chemical notation), and one or more of a small amount of MgO, SO3 ($ in cement chemical notation), TiO2, P2O5, Na2O, and K2O.

[0016] Examples of the aluminosilicate of the present invention are steelmaking slag, Class F fly ash according to ASTM C618, clay minerals, especially calcined clay, glass pumice, vitreous volcanic ash, zeolitized tuff, diatomaceous earth, burned oil shale, and combustion residues of organic substances. According to a preferred embodiment, the first aluminosilicate is steelmaking slag, and the further aluminosilicate is selected from Class F fly ash according to ASTM C618 and / or calcined clay.

[0017] The steelmaking slag in this situation is a by-product of the steelmaking process. The steelmaking slag is obtained, for example, when converting iron to steel in the Thomas process, Linz-Donawitz process, Siemens-Martin process, or an electric arc furnace. The steelmaking slag is produced when treating hot untreated iron with oxygen to remove carbon and another element having a higher affinity for oxygen than iron. The liquid slag is separated from the crude steel and cooled in a pit or ground bay to form crystalline or partially crystalline steelmaking slag. The cooled slag can then be crushed, pulverized, and sieved to obtain the desired powder fineness.

[0018] Steelmaking slag may be any slag obtained from steelmaking. In particular, the steelmaking slag is any one of granulated blast furnace slag (GGBFS), basic oxygen furnace slag (BOS), ladle slag, or electric arc furnace slag. According to a preferred embodiment, the steelmaking slag is granulated blast furnace slag powder. Particularly preferably, the steelmaking slag, especially GGBFS, has a Blaine fineness of at least 4000 cm 2 / g, preferably at least 4500 cm 2 / g, a glass content of at least 75%, and a weight ratio of CaO + MgO / SiO2 + Al2O3 of at least 1. The Blaine fineness can be measured in accordance with the standard ASTM C204-18e1 or the standard NF EN 196-6.

[0019] In this situation, the clay minerals are solid materials composed of at least 30% by weight, preferably at least 45% by weight, and particularly at least 75% by weight of clay minerals based on the dry weight. Such clay minerals preferably belong to the kaolin group (such as kaolinite, dickite, nacrite, or halloysite), the smectite group (such as montmorillonite, nontronite, or saponite), the vermiculite group, serpentine, palygorskite, sepiolite, chlorite, talc, pyrophyllite, mica (such as biotite, muscovite, illite, glauconite, sericite, and fencite), or mixtures thereof. Clay minerals belonging to the kaolin group, particularly kaolinite, and mica, particularly muscovite and illite, and mixtures thereof are particularly preferred. The clay minerals in this situation can be any type of clay minerals, such as raw clay, low-temperature fired clay, or high-temperature fired clay. Raw clay is, for example, clay minerals collected from a quarry, optionally purified, and optionally dried. Low-temperature fired clay is clay heat-treated at a temperature between 500 and 1200 °C. For example, low-temperature fired clay minerals can be produced in a rotary kiln or a flash calciner. High-temperature fired clay is clay minerals heat-treated at a temperature exceeding 1200 °C, typically between 1300 and 1400 °C. High-temperature fired clay is typically crystalline or contains a large amount of crystalline phases, particularly mullite.

[0020] The clay mineral in this situation is preferably low-temperature calcined clay. The low-temperature calcined clay is preferably a clay material that has undergone heat treatment at a temperature between 500 and 1200 °C or a flash firing process at a temperature between 800 and 1100 °C. A suitable flash firing process is described, for example, in WO 2014 / 085538. According to a particularly preferred embodiment of the present invention, the calcined clay is metakaolin. Metakaolin is a material obtained by the low-temperature calcination of kaolinite or a mineral rich in kaolinite, having a kaolinite content of at least 30 wt%, preferably up to at least 35 wt% based on its dry weight. The firing temperature for producing metakaolin is typically in the range of 500 to 900 °C.

[0021] The particle size of the aluminosilicate material of the present invention can be analyzed by sieve analysis as described in the standard ASTM C136 / C136M. This method separates fine particles from coarser particles by passing the material through a number of sieves of different mesh sizes. The material to be analyzed is vibrated through a series of successively smaller sieves using one or a combination of horizontal, vertical, or rotational motion. As a result, the percentage value of the particles retained on a particular size sieve is determined.

[0022] According to an embodiment, the appropriate particle size D50 of the aluminosilicate material of the present invention is between 1 μm and 100 μm, preferably between 2 μm and 30 μm. The particle size D50 of a particular material is the particle size at which 50% of the particles of this material are larger and 50% of the particles are smaller. According to a particular embodiment, both the particle size D10 and D90 of the aluminosilicate material of the present invention are between 0.5 μm and 100 μm, preferably between 1 μm and 50 μm. The particle size D10 of a particular material is the particle size at which 90% of the particles of this material are larger and 10% of the particles are smaller, and the particle size D90 is the particle size at which 10% of the particles are larger and 90% of the particles are smaller.

[0023] One measure of the fineness of the aluminosilicate material of the present invention is the Blaine fineness. The Blaine fineness can be measured in accordance with Standard ASTM C204-18e1 or Standard NF EN 196-6.

[0024] According to an embodiment, the Blaine surface of the aluminosilicate of the present invention, particularly steelmaking slag, is over 3000 cm 2 / g, preferably over 4000 cm 2 / g, more preferably over 4500 cm 2 / g, even more preferably over 5000 cm 2 / g, and particularly over 6000 cm 2 / g. Typically, the aluminosilicate of the present invention has a Blaine fineness of less than 12000 cm 2 / g.

[0025] In this context, it is important that at least two chemically different aluminosilicates are used in the cementitious binder for geopolymers. "Chemically different" means that the chemical composition of each aluminosilicate, measured by XRF as described in EN 196-2:2013, is different. It is possible to use a combination of two chemically different aluminosilicates, or a combination of three chemically different aluminosilicates, or a combination of four or more chemically different aluminosilicates.

[0026] According to an embodiment, at least two chemically different aluminosilicates are Class F fly ash according to ASTM C618 and steelmaking slag, particularly granulated blast furnace slag powder. Thus, according to an embodiment, the cementitious binder of the present invention is characterized in that at least two chemically different aluminosilicates are selected from steelmaking slag and Class F fly ash according to ASTM C618, preferably with a weight ratio of steelmaking slag to fly ash of between 1.5:1 and 1:2, preferably between 1.3:1 and 1:1.5.

[0027] According to a further embodiment, at least two chemically different aluminosilicates are class F fly ash according to ASTM C618, steelmaking slag, in particular granulated blast furnace slag powder, and clay minerals, preferably calcined clay, in particular metakaolin.

[0028] According to a further embodiment, two chemically different aluminosilicates selected from steelmaking slag, in particular granulated blast furnace slag powder, and clay minerals, preferably calcined clay, in particular metakaolin, are present in the cementitious binder of the present invention.

[0029] According to a further embodiment, at least two chemically different aluminosilicates are class F fly ash according to ASTM C618, and clay minerals, preferably calcined clay, in particular metakaolin.

[0030] By using a combination of at least two chemically different aluminosilicates, in particular a combination of class F fly ash according to ASTM C618 and granulated blast furnace slag powder, or a combination of class F fly ash according to ASTM C618, granulated blast furnace slag powder, and calcined clay, in particular metakaolin, or a combination of granulated blast furnace slag powder and calcined clay, in particular metakaolin, the resistance of the cementitious binder for geopolymers or the cured geopolymers according to the present invention to acid attack increases.

[0031] At least two chemically different aluminosilicates are present in the cementitious binder for geopolymers in an amount of 30% by weight or more, preferably between 30% and 70% by weight, based on the total dry weight of the cementitious binder. This weight percentage value relates to the sum of all aluminosilicates present.

[0032] The ordinary Portland cement in this situation may be any one of the cements conforming to the standard ASTM C150. The ordinary Portland cement may also be the cement of types CEM I or CEM II / A-L, B-L, A-LL, B-LL conforming to the standard EN 197-1. Naturally, equivalent cements conforming to alternative standards, such as those of Japan, China, or India, are equally suitable. White Portland cement is also a suitable type of ordinary Portland cement.

[0033] The ordinary Portland cement is present in the cementitious binder for geopolymers in an amount of 20% by weight or more, preferably between 20% and 60% by weight, based on the total dry weight of the cementitious binder.

[0034] According to an embodiment, in the cementitious binder of the present invention, the weight ratio of the ordinary Portland cement to the sum of at least two heat-activated aluminosilicates is between 0.1 and 2, preferably between 0.3 and 2, more preferably between 0.6 and 1.6. When calculating this ratio, the total weight of all the heat-activated aluminosilicates present should be used.

[0035] The calcium sulfoaluminate cement (CSA cement) of the present invention is a cement containing a clinker containing C4(A 3-x F x )$(C: CaO; A: Al2O3; F: Fe2O3; $: SO3), where x is an integer from 0 to 3. The CSA of the present invention typically contains aluminates (CA, C3A, C 12A7) It includes a further phase selected from belite (C2S), ferrite (C2F, C2AF, C4AF), ternesite (C5S2$), and anhydrite. According to certain embodiments, the CSA of the present invention comprises, based on the total dry weight of the CSA cement, 15 - 75 wt% of C4A3$, 0 - 10 wt% of aluminate, 0 - 70 wt% of belite, 0 - 35 wt% of ferrite, 0 - 20 wt% of ternesite, and 0 - 20 wt% of anhydrite. Suitable CSA is commercially available, for example, from Heidelberg Cement AG, Buzzi Unicem, or commercially available under the trade name Calumex from Caltra B.V.

[0036] The calcium aluminate cement (CAC) of the present invention is preferably a cement compliant with the standard EN 14647:2006 - 01. However, the calcium aluminate cement of the present invention may also be an amorphous material mainly composed of an amorphous calcium aluminate phase.

[0037] The calcium sulfate source may be any source of CaSO4 anhydrite (also referred to as anhydrite throughout the present invention), CaSO4 α - and β - hemihydrates, and CaSO4 dihydrate. The calcium sulfate source is, for example, natural gypsum, phosphogypsum, and FGD - gypsum. It has been found that anhydrite gives the best performance in this situation. Thus, according to a preferred embodiment, in the cementitious binder of the present invention, the calcium sulfate source is anhydrite.

[0038] The weight ratio of calcium sulfate in the cementitious binder of the present invention to calcium sulfoaluminate and / or calcium aluminate is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.5 and 1.1. When calculating this ratio, it is necessary to consider all the calcium sulfate present in the cementitious binder. In the aluminate phase, especially C4(A 3-x F x) The calcium sulfate that combines therein should not be regarded as the calcium sulfate when calculating this ratio. When calculating this ratio, it is necessary to consider all the useful calcium aluminate and calcium sulfoaluminate phases contained in the calcium sulfoaluminate cement or calcium aluminate cement. Such useful phases are as described above, and particularly useful phases are C4(A 3-x F x ) (where x is an integer from 0 to 3), CA, C3A, C 12 A7, C2AF, and / or C4AF.

[0039] It is important for ensuring high dimensional stability of the geopolymers upon curing that the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.6 and 1.1. High dimensional stability means, in particular, low autogenous shrinkage or chemical shrinkage, and little expansion. When used throughout the present invention, shrinkage or expansion is measurable in accordance with the standard ASTM C157 / C157 - M08.

[0040] As described above, according to an embodiment, two chemically different aluminosilicates selected from class F fly ash according to ASTM C618 and steelmaking slag, particularly granulated blast furnace slag powder, are present in the cementitious binder of the present invention. In particular, in such an embodiment, the presence of calcium sulfate, and calcium sulfoaluminate and / or calcium aluminate in a specific weight ratio serves to reliably achieve the targeted resistance of the geopolymer composition after curing to chemical attack.

[0041] According to an embodiment, the cementitious binder of the present invention further contains 5 to 15% by weight, preferably 6 to 8% by weight, of silica fume based on the total dry weight of the cementitious binder. By further using silica fume, the resistance of the cementitious binder for geopolymers according to the present invention or the cured geopolymers to acid attack is further increased. Furthermore, it has been found that by using silica fume, the adhesiveness of the cementitious binder of the present invention or the geopolymer composition of the present invention during shotcreting and / or in vertical or overhead applications can be improved.

[0042] According to an embodiment, the cementitious binder for geopolymers is (in each case, based on the total dry weight of the cementitious binder) a) a mixture of 30 to 70% by weight of at least two chemically different aluminosilicates, and b) 20 to 60% by weight of ordinary Portland cement, and c) a mixture of 8 to 20% by weight of calcium sulfoaluminate cement or a mixture of calcium aluminate cement and a calcium sulfate source, wherein in the mixture, the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.6 and 1.1, comprising or consisting of.

[0043] According to a particularly useful embodiment, the cementitious binder for geopolymers is (in each case, based on the total dry weight of the cementitious binder) a) a mixture of 30% by weight or more of Class F fly ash according to ASTM C618, steelmaking slag, particularly granulated blast furnace slag powder, and clay minerals, preferably calcined clay, particularly metakaolin, and b) 20% by weight or more of ordinary Portland cement, and c) 8 to 20% by weight of calcium sulfoaluminate cement or a mixture of calcium aluminate cement and a calcium sulfate source, wherein in said mixture, the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.5 and 1.1, and d) 5 to 15% by weight, preferably 6 to 8% by weight of silica fume, and comprises or consists of.

[0044] According to a further particularly useful embodiment, the cementitious binder for geopolymers is (in each case based on the total dry weight of the cementitious binder) a) a mixture of 40 to 50% by weight of granulated blast furnace slag powder and a clay mineral, preferably calcined clay, in particular metakaolin, and b) 20 to 30% by weight of ordinary Portland cement, and c) 14 to 20% by weight of calcium sulfoaluminate cement or a mixture of calcium aluminate cement and a calcium sulfate source, wherein in said mixture, the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate is between 0.08 and 1.5, preferably between 0.3 and 1.1, more preferably between 0.6 and 1.1, and comprises or consists of.

[0045] According to an embodiment, in the cementitious binder of the present invention, when silica fume, calcined clay, and Class F fly ash according to ASTM C618 are present, the weight ratio of the total of silica fume and calcined clay to fly ash is between 0.1 and 0.5. Thus, the total of silica fume and calcined clay means the total weight of silica fume and calcined clay present in the composition.

[0046] The cementitious binder for geopolymers or the geopolymers of the present invention preferably do not contain any alkali silicate, particularly do not contain sodium silicate or potassium silicate.

[0047] In a second aspect, the present invention relates to a) the aforementioned cementitious binder, and b) aggregates and / or fillers, and c) optionally further additives, and refers to a geopololymer composition comprising the same.

[0048] The aggregate can be any material that is non-reactive in the hydration reaction of the hydraulic binder. The aggregate can be any aggregate typically used in cementitious compositions. Typical aggregates are, for example, rocks, crushed stones, gravels, sands, especially silica sand, river sand, and / or crushed sand, recycled concrete, glass, expanded glass, hollow glass beads, glass ceramics, perlite, vermiculite, quarry waste, raw, fired, or melted earth or clay, porcelain, electrically melted or sintered abrasives, fired supports, silica xerogel, or biological aggregates such as plant materials. Fillers are fine aggregates. Fillers are, in particular, limestone powder, dolomite powder, and / or aluminum oxide powder.

[0049] Particularly preferred aggregates are sands. Sand is a natural granular material composed of finely crushed rock or mineral particles. It is available in various forms and sizes. Examples of suitable sands are silica sand, limestone sand, river sand, or crushed aggregates. Suitable sands are described, for example, in the standards ASTM C778 or EN 196-1.

[0050] Further additives can be any other additives common in the mortar and / or concrete industry, such as plasticizers and / or superplasticizers, air-entraining agents, defoamers, stabilizers, rheology modifiers, in particular thickeners, water reducers, accelerators, retarders, shrinkage reducing agents, stimulants, promoters, water resistance agents, strength improvers, fibers, dust suppressants, foaming agents, pigments, corrosion inhibitors, biocides, and / or chromium (VI) reducing agents, etc. It may be advantageous to combine two or more of the described further additives in one cementitious composition. In particular, thickener superplasticizers, accelerators, and retarders.

[0051] According to an embodiment, the further additive is selected from lithium carbonate, alkali silicate, particularly sodium silicate or potassium silicate, citric acid, tartaric acid, sugar, sugar acid, sugar alcohol, aluminum sulfate, modified cellulose, organosilane, glycol, magnesium oxide, calcium oxide, calcium silicate hydrate, phosphate, polycarboxylate ether, naphthalenesulfonate, ligninsulfonate, and / or melamine formaldehyde condensate.

[0052] According to an embodiment of the present invention, the diopolymer composition contains, in each case based on the total dry weight of the diopolymer composition, 20 to 60% by weight, preferably 30 to 45% by weight, of the aforementioned cementitious binder, 40 to 70% by weight, preferably 50 to 65% by weight, of aggregate and / or filler, and 0 to 10% by weight, preferably 0.1 to 5% by weight, of a further additive.

[0053] According to an embodiment, the diopolymer composition of the present invention is a dry composition. The dry composition means that the water content is less than 5% by weight, preferably less than 1% by weight, based on the total weight of the composition.

[0054] The dry diopolymer composition of the present invention can be mixed with water. The solidification and hardening of the diopolymer composition start when it comes into contact with water. The appropriate weight of water to the cementitious binder in the diopolymer composition is between 0.2 and 0.7, preferably between 0.3 and 0.5.

[0055] According to an embodiment, the diopolymer composition of the present invention is a wet diopolymer composition. The wet diopolymer composition contains a) the aforementioned cementitious binder, b) aggregate and / or filler, c) optionally a further additive, d) water in an amount such that the weight ratio of water to the cementitious binder is between 0.2 and 0.7, preferably between 0.3 and 0.5. and.

[0056] All of the embodiments described as preferred above are also relevant to this aspect.

[0057] The cementitious binders of the present invention, and geopolymers based on such binders, can be used in a variety of construction methods.

[0058] In a further aspect, the present invention provides a method for repairing a concrete or mortar structure or a masonry, comprising: a) providing the cementitious binder or the geopolymer composition as described above; b) mixing the cementitious binder or the geopolymer composition provided in step a) with water; c) applying the mixture obtained in step b) to the surface of the hardened concrete or mortar structure; d) optionally, curing the applied mixture. The method includes the above steps.

[0059] The mixing in step b) can be carried out by any means well known to those skilled in the art. For example, the mixing can be carried out by a hand-held stirrer, a Hobart mixer, a mixing bucket, a paddle mixer, a jet mixer, a screw mixer, an auger mixer, a horizontal single-shaft mixer, a twin-shaft paddle mixer, a vertical-shaft mixer, a ribbon blender, an orbital mixer, a change-can mixer, a vertical stirring chamber, or an air agitation operation. The mixing can be continuous, semi-continuous, or batchwise. Continuous mixing offers the advantage of high material throughput.

[0060] The application in step c) can be carried out by any means well known to those skilled in the art. According to an embodiment, the mixture is applied in step c) by means of a trowel, a brush, or a roller. According to another embodiment, the mixture is applied in step c) by means of a spraying device. Spraying has the advantage that the application can be carried out very quickly in a continuous manner. Devices suitable for spraying applications are well known to those skilled in the art. The mixture can be applied in step c) with various thicknesses according to actual needs. It is also possible to apply the mixture in step c) so as to fill holes or cracks.

[0061] The curing in step d) is typically carried out by leaving the applied mixture under environmental conditions. Thus, according to an embodiment, the curing is carried out at a temperature between 5 and 35 °C and a pressure of about 1023 mbar. According to another embodiment, the curing is carried out at a high temperature, for example above 40 °C and up to a temperature of 100 °C or 120 °C.

[0062] According to an embodiment, the method for repairing a concrete or mortar structure or a masonry is a method that conforms to the principles of standard EN 1504-9:2008. In particular, the method for repairing a concrete or mortar structure or a masonry conforms to Principle 2, especially 2.2, Principle 3, especially 3.1 and 3.3, Principle 4, especially 4.4, 4.5, 4.6, Principle 5, especially 5.1 and 5.3, Principle 6, Principle 7, especially 7.1, or Principle 8, especially 8.2 of the standard EN 1504-9:2008.

[0063] In particular, the method for repairing a concrete or mortar structure or a masonry of the present invention is suitable in an environment where there is contact with aggressive chemical substances, especially acidic aqueous solutions, sulfates, chlorides, and / or salt water.

[0064] In a further aspect, the present invention is a method for protecting a structure, especially a concrete or mortar structure or a masonry structure, comprising a) providing the cementitious binder or the geopolymer composition as described above; b) mixing the cementitious binder or the geopolymer composition provided in step a) with water; c) applying the mixture obtained in step b) to the surface of the cured structure; d) optionally, curing the applied mixture; and relates to a method comprising the same.

[0065] In particular, mixing, application, and curing in the method for protecting a structure can be performed as described above.

[0066] The structure treated by the protection method of the present invention may be a structure that is permanently dry, a structure that is frequently wetted, such as a wet room, or a structure that is permanently in contact with water. For example, the structure to be treated may be a balcony, a bathroom, a kitchen, a swimming pool, a port structure, a water pipe, a water tank, a sewage structure, a sewer pipe, a manhole, a lift station, a pump yard, a collection device, a wastewater treatment plant, a coastal area, or a part of a ship's bridge deck, such as a floor, a wall, and / or a ceiling.

[0067] In particular, the method for protecting a structure of the present invention is suitable in an environment where there is contact with aggressive chemicals, especially acidic aqueous solutions and / or salt water.

[0068] In a further aspect, the present invention relates to a method for waterproofing a structure, particularly a concrete or mortar structure or a masonry structure, comprising: a) providing the cementitious binder or the geopolymer composition as described above; b) mixing the cementitious binder or the geopolymer composition provided in step a) with water; c) applying the mixture obtained in step b) to the surface of the cured structure; d) optionally, curing the applied mixture; and relates to a method comprising the same.

[0069] In particular, mixing, application, and curing in the waterproofing treatment method of the structure can be performed as described above.

[0070] The term "waterproofing treatment" in this context includes both waterproofing treatment and moisture-proofing treatment as defined in ACI 515.1R-85.

[0071] The structure treated by the waterproofing treatment method of the present invention may be a structure that is permanently dry, a structure that is frequently wetted, such as a wet room, or a structure that is in permanent contact with water. For example, the structure to be treated may be a balcony, a bathroom, a kitchen, a swimming pool, a port structure, a water pipe, a water tank, a sewage structure, a sewer pipe, a manhole, a lift station, a pump yard, a collection device, a wastewater treatment plant, a coastal area, or a part of a bridge deck, such as a floor, a wall, and / or a ceiling.

[0072] In particular, the waterproofing treatment method of the structure of the present invention is suitable in an environment where there is contact with aggressive chemicals, particularly acidic aqueous solutions and / or salt water.

[0073] In a further aspect, the present invention is a method for 3D printing a mortar composition, a) providing the cementitious binder or the geopololymer composition as described above; b) mixing the cementitious binder or geopololymer composition provided in step a) with water; c) optionally, transferring the mixture obtained in step b) to a print head, preferably a print head mounted on a movable arm; c) applying the mixture obtained in step b) layer by layer from the print head to form a three-dimensional object; d) optionally, curing the three-dimensional object; and relates to a method comprising the above steps.

[0074] According to a preferred embodiment, in the 3D printing method of the present invention, a cementitious binder or geopololymer composition in which two chemically different aluminosilicates are selected from steelmaking slag, particularly granulated blast furnace slag powder, and clay minerals, preferably calcined clay, particularly metakaolin, is used. The preferred weight ratio of steelmaking slag, particularly granulated blast furnace slag powder, to clay minerals, preferably calcined clay, particularly metakaolin, in the cementitious binder for geopolymers used in the 3D printing method is between 2:1 and 5:1, particularly 3.5:1. The total amount of clay minerals, preferably calcined clay, particularly metakaolin, in the cementitious binder for geopolymers used in the 3D printing method is preferably 20% by weight or less, more preferably 16% by weight or less, and even more preferably 11% by weight or less. In particular, a larger amount of metakaolin can cause insufficient extrusion and higher pressure during extrusion. Further, fly ash can be present.

[0075] In particular, mixing, application, and curing in the 3D printing method of the mortar composition can be performed as described above.

[0076] In particular, the 3D printing method of the mortar composition can be performed using an apparatus as described below. For example, any of the features described below in connection with this apparatus can be implemented in the method described above accordingly.

[0077] According to an embodiment, an apparatus for manufacturing a three-dimensional object, particularly a robot system, in the method of the present invention includes a supply device for a cementitious binder or geopololymer composition mixed with water, a supply line for supplying the cementitious binder or geopololymer composition mixed with water to a print head, a mixing unit, and a control unit.

[0078] Preferably, the mixing unit is a static and / or dynamic mixer and is arranged downstream of the supply device and upstream of the outlet nozzle. In particular, the mixing unit is arranged such that the cementitious binder or geopololymer composition mixed with water is mixed before entering the supply line, when passing through the supply line, and / or after leaving the supply line.

[0079] The device includes a print head that is preferably movable in at least one spatial direction to form a three-dimensional structure. The print head has a print head outlet, in particular an outlet nozzle, for applying a cementitious binder or geopololymer composition mixed with water. Optionally, the print head can include a controllable outlet, in particular in the form of an openable and closable outlet nozzle. In this case, the openable and closable outlet nozzle is preferably controllable by a control unit.

[0080] According to an embodiment, the device includes at least one mixer, in particular a static and / or dynamic mixer, which is arranged downstream of the supply device for adding an additive to the cementitious binder or geopololymer composition mixed with water. In particular, at least one mixer is arranged between (i) the print head outlet, in particular the outlet nozzle, and (ii) the supply device and the inlet nozzle for adding an additive to the cementitious binder or geopololymer composition mixed with water. In a further preferred embodiment, the device optionally includes an additive supply device having an additive inlet nozzle configured to add an additive to the cementitious binder or geopololymer composition mixed with water in the print head, in the mixing device, and / or in the supply line.

[0081] According to an embodiment, the control unit of the device includes a processor, a storage device, a plurality of interfaces for receiving data, and a plurality of interfaces for controlling the individual components of the device.

[0082] Figure 1 schematically shows a representative system 1 for performing a 3D printing method according to the present invention.

[0083] System 1 includes a moving device 2 having a movable arm 2.1. A print head 3 is attached to the free end of the arm 2.1, which can be moved in all three spatial dimensions by the arm 2.1. As a result, the print head 3 can move to any position within the operating area of the moving device 2.

[0084] Internally, the print head 3 has a tubular passage 3.1 through which a mixture of a cementitious material and water passes, extending from the end face facing the arm 2.1 (the upper part in FIG. 1) to the opposite free end face. At the free end, the passage 3.1 opens into a controllable outlet 4 in the form of a nozzle that can be continuously opened and closed.

[0085] In some embodiments, an inlet nozzle 5 for adding an additive opens laterally into the passage 3.1 within the region facing the arm 2.1. Through the inlet nozzle 5, an additive, such as a rheology aid, can be added as needed to the mixture of the cementitious material and water moving through the passage 3.1.

[0086] According to an embodiment, inside the print head 3 downstream of the inlet nozzle, a static mixer 6 is arranged in the passage 3.1, which further mixes the mixture of the cementitious material, water, and optional additive.

[0087] A measuring unit 8 for determining the pressure within the tubular passage 3.1 can be arranged within the region of the controllable outlet 4. The sampling rate of the measuring unit 8 is, for example, 10 Hz.

[0088] According to an embodiment, a device 7 for degassing the mixture of the cementitious material and water is also attached to the print head 3. This device is designed as a vacuum treatment device and can reduce the amount of air in the mixture of the cementitious material and water. For this purpose, for example, a section of the wall of the passage 3.1 can be designed as a gas-permeable membrane, whereby air is extracted from the mixture of the cementitious material and water by evacuating the outside of the passage 3.1.

[0089] A system 1 for applying a mixture of a cementitious material and water has a supply device 9 corresponding to the input side having containers 11.1, 11.2, and optionally 11.3 and 11.4. Container 11.1 houses a first component which is a cementitious composition for geopolymers or a geopolymer composition according to the present invention. The second component present in the second container 11.2 consists of water. The third component is optional. In the optional additive reservoir 11.4, optionally, for example, a rheology aid is present.

[0090] On the discharge side, the supply device 9 has at least two, optionally three separate outlets, each of which is connected to one of the inlets 10.1, 10.2, and optionally 10.3 of the mixing device 10. The supply device 9 also has individually controllable metering devices (not shown in FIG. 1), whereby the individual components in the individual containers 11.1, 11.2, and optionally 11.3 and 11.4 can be metered and supplied individually into the mixing device 10.

[0091] According to an embodiment, the mixing device 10 is designed as a static mixer or as a dynamic mixer, preferably as a continuous dynamic mixer, and in addition can include an integrated transfer device in the form of a screw conveyor. In the mixing device, the individually metered components are mixed together and transferred to the flexible conduit 12 attached to the outlet side of the mixing device.

[0092] The mixture of the cementitious material and water can be transferred through the flexible conduit 12 which is open up to the tubular passage 3.1 at the end of the print head facing the arm 2.1 up to the print head 3 and can be continuously applied through the controllable outlet 4.

[0093] Optionally, a part of the system 1 is also the measuring unit 13, which is integrated into the delivery line 12 in the region between the mixing device 10 and the print head 3. This measuring unit includes, for example, an ultrasonic transducer designed to determine the flow characteristics of a mixture of a cementitious material and water. The sampling rate of the measuring unit 13 is, for example, 10 Hz.

[0094] The central control unit 14 of the system 1 includes a processor, a storage device, a plurality of interfaces for receiving data, and a plurality of interfaces for controlling the individual components of the system 1.

[0095] In this regard, the mixing device 10 is connected to the control unit 14 via a first control line 15a, while the supply device is connected to the control unit 14 via a second control line 15b. As a result, the individual components in the containers 11.1, 11.2, and optionally 11.3 can be metered and supplied into the mixing device 10 by the central control unit according to a predetermined recipe stored in the control unit, and can be transferred into the deflecting line 12 at an adjustable transfer speed.

[0096] Each of the controllable outlet 4, the inlet nozzle 5, and optionally the device 7 for degassing the mixture of the cementitious material and water at the print head is similarly connected to the control unit 14 via separate control lines 15c, 15d, 15e, and can be controlled or monitored by the control unit 14.

[0097] The moving device 2 is also connected to the control unit 14 via a further control line 15g. This means that the movement of the print head 3 can be controlled by the control unit 14.

[0098] If the measuring unit 8 is present, it is connected to the control unit 14 by a data line 15h, whereby the print data recorded in the unit can be transmitted to the control unit 14.

[0099] Similarly, when the measuring unit 13 is present, it is connected to the control unit 14 by the data line 15f, whereby data characterizing the flow properties recorded in the measuring unit can be transmitted to the control unit 14.

[0100] In a further aspect, the invention is a shotcreting method comprising: a) providing the cementitious binder or the geopolymer composition as described above; b) mixing the cementitious binder or geopolymer composition provided in step a) with water; c) transferring the mixture obtained in step b) to a gun; d) optionally mixing an additional accelerator with the mixture obtained in step b); c) spraying the mixture from the gun into voids and / or onto a surface; d) optionally curing the mixture. The invention relates to a method comprising the above steps.

[0101] According to an embodiment, the additional accelerator added in step d) is an accelerator for shotcrete, in particular a composition based on aluminum sulfate. Preferably, the composition based on aluminum sulfate is added to the mixture prepared in step b) during transfer or in the gun.

[0102] Guns suitable for spraying the mixture in step c) are well known to those skilled in the art. In particular, suitable guns are conventional guns for shotcrete (also called sprayed concrete), preferably having a spray nozzle.

[0103] According to an embodiment, in the shotcreting method according to the present invention, a base material is coated. In particular, the base material is the surface of a tunnel, a mine, a cave, a bay, a well, and / or a drainage ditch. According to a further embodiment, in the shotcreting method according to the present invention, voids are filled. According to a further embodiment, in the shotcreting method according to the present invention, a free-form structure is formed.

Brief Description of the Drawings

[0104]

Figure 1

Examples

[0105] Table 1 below shows an overview of the chemical composition of some of the raw materials used.

[0106]

Table 1

[0107] White ordinary Portland cement Type I (w-PC) with a Blaine fineness of 4280 cm2 / g from Royal White Cement was used.

[0108] Calcium sulfoaluminate cement (CSA) in an amount of 69.4 wt% C4A3$, 2.6 wt% anhydrous gypsum, and <25 wt% C2S was used.

[0109] The calcium sulfate used was anhydrous gypsum.

[0110] The sand used was a mixture of silica sand with a particle size of 0.1 - 2.5 mm.

[0111] The fine filler (filer) used was feldspar powder with an average particle size of 45 microns.

[0112] The polycarboxylate ether (PCE) of type Melflux 6681 supplied by Azelis Americas Inc was used as an additive.

[0113] Example 1 - Geopolymer Test To prepare a cementitious binder or geopolymer formulation for geopolymers, the dry components in the amounts shown in Tables 2 - 5 below were weighed into a Hobart mixer and mixed for 3 minutes at 23°C and 50% relative humidity. Next, water was added to achieve the cementitious binder to water weight ratio (w / b ratio) shown in Tables 2 - 5 below, and mixing was continued for an additional 3 minutes. Test specimens were cast directly from the resulting geopolymer compositions. Measurements were taken as follows.

[0114] Shrinkage was measured in accordance with Standard ASTM C157 / C157 - M08 after curing at 23°C / 50% r.h. for 24 hours. Shrinkage of 1500 μm / m or less is desirable. In this situation, expansion (shown as positive values in Tables 2 - 5 below) is preferred over shrinkage.

[0115] Compressive strength (described as C.S. in Tables 2 - 5 below) was determined in accordance with Standard ASTM C109 / C109M using cylinders 25.4 mm in height and 25.4 mm in diameter. Compressive strength was measured after curing at 23°C / 90% r.h. for 7 days and subsequent immersion in tap water for 7 days.

[0116] Acid resistance (described as A.R. in Tables 2-5 below) was measured by comparing the compressive strength of the test specimens. For comparison, as described above, in accordance with ASTM C109 / C109M, a first test specimen was made from each mixture. A second test specimen was made from each mixture in the same procedure, but instead of curing at 23 °C / 90% r.h. for 7 days and then immersing in tap water for 7 days, this second test specimen was cured at 23 °C / 90% r.h. for 7 days and then immersed in 0.5 M sulfuric acid for 7 days. The difference in compressive strength between each of the two test specimens was calculated and reported below as a difference in % units (negative values indicate a decrease in compressive strength during storage in acid, and positive values indicate an increase in compressive strength during storage in acid).

[0117] For ease of reference, the calculated weight ratio of calcium sulfate to calcium sulfoaluminate (Ratio C$:CSA) is shown in Tables 2-5 below for each mixture.

[0118] Compositions C-1 to C-9 are not according to the present invention and are included for comparison purposes. Compositions G-1 to G-13 are according to the present invention.

[0119]

Table 2

[0120] As can be seen from the above examples, the geopolimer composition (C-1) according to Davidovits' teachings gives good strength and acid resistance, but also shows a very large shrinkage. The use of a Portland cement-based binder reduces shrinkage, but also reduces acid resistance (Examples C-2 to C-4). Even when using Portland cement, CSA, and calcium sulfate in combination without using aluminosilicate, acceptable shrinkage was obtained, but the acid resistance was low. Interestingly, when using the only aluminosilicate in combination with a binder based on Portland cement, CSA, and calcium sulfate, it was insufficient to obtain high strength, and at the same time the acid resistance increased (see Examples C-6 and C-7).

[0121] When CSA was used alone without any anhydride, low shrinkage was obtained, but the desired acid resistance was achieved.

[0122]

Table 3

[0123] As can be seen from the results in Table 3, by combining at least two chemically different aluminosilicates with a binder based on Portland cement, CSA, and calcium sulfate, the acid resistance is enhanced and furthermore low shrinkage is exhibited.

[0124] Also, when the ratio of the weight of calcium sulfate to calcium sulfoaluminate increases, the shrinkage is improved (Examples G-2 to G-4).

[0125] By partially replacing fly ash with metakaolin and silica fume, the acid resistance was further enhanced.

[0126]

Table 4

[0127] From the results in Table 4 above, it can be seen that when the weight ratio of calcium sulfate to calcium sulfoaluminate increases, the shrinkage is improved (Examples G-7 to G-9).

[0128] Also, when comparing the results from Tables 3 and 4 (see Examples G-1 and G-10), it can be seen that when the weight ratio of GGBS to fly ash increases, the strength increases but the acid resistance decreases. However, it should be noted that the acid resistance was acceptable in both of these examples.

[0129]

Table 5

[0130] From the results in Table 5, it can be seen that the composition according to the present invention has very low shrinkage and high compressive strength compared to the reference. The binder having a combination of GGBS and fly ash had lower shrinkage than the binder having a combination of GGBS and metakaolin, but also slightly lower compressive strength (see Examples G-10 and G-11). By adding additional silica fume, the shrinkage can be further reduced and the compressive strength and acid resistance can be increased (see Examples G-13 and G-10). The balance ratio of GGBS to fly ash can also further reduce shrinkage and improve acid resistance (see Examples G11 and G-12).

[0131] Example 2 - 3D Printing The geopolimer composition was 3D printed using the system shown in Figure 1. Layers of material 5 cm wide and 0.5 cm high were applied. The geopolimer composition consisted of (the raw materials mentioned above): 16.3 wt% GGBS, 9.4 wt% w-PC, 2 wt% MK, 5.8 wt% CSA, 0.5 wt% CaSO4, 43 wt% sand, 16.7 wt% CaCO3 powder (D50: about 30 μm), 5 wt% CaCO3 fine filler (D50: 0.8 μm), 0.2 wt% PCE, and 1.1 wt% additives (a mixture of diutan gum and modified cellulose thickener, gluconate, and aluminum sulfate). A water-to-powder weight ratio of 0.16 was used.

[0132] According to visual inspection, it showed good printability as indicated by all of the following: individual layers showed very limited sagging and did not flow, the adhesion between layers was good, and at least three layers could be applied on top of each other. The printing time for forming an object 20 cm high was 13 minutes. The initial hose pressure was 200 psi and the final hose pressure was 260 psi. Thus, the geopolimer composition according to the present invention showed smooth extrusion and excellent finish.

[0133] The strength of the printed object at 24 hours and 28 days was high. Surprisingly, it was higher than that of an object printed using a conventional cement-based 3D printing ink.

Description of Symbols

[0134] 1 System for 3D printing of mortar compositions 2 Moving device 2.1 Movable arm 3 Print head 3.1 Passageway 4 Outlet 5 Inlet nozzle 6 Static mixer 7 Degassing device 8 Measuring unit 9 Feeding device 10 Mixing device 10.1~10.3 Inlet 11.1~11.4 Container 12 Flexible pipeline 13 Measuring unit 14 Control unit 15a~15h Control line, data line

Claims

1. A cement-based binder for geopolymers, wherein the cement-based binder is based on the total dry weight of the cement-based binder in each case. (a) A mixture of at least 30% by weight of two chemically different aluminosilicates, (b) 20% by weight or more of ordinary Portland cement, (c) A mixture of 8 to 20% by weight of calcium sulfoaluminate cement or calcium aluminate cement with a calcium sulfate source, wherein the weight ratio of calcium sulfate to calcium sulfoaluminate and / or calcium aluminate in the mixture is 0.08 to 1.5, preferably 0.3 to 1.1, more preferably 0.6 to 1.1, A cement-based binder containing [the specified ingredient].

2. The cement-based binder according to claim 1, wherein the at least two chemically distinct aluminosilicates are selected from steelmaking slag and class F fly ash according to ASTM C618, preferably with a weight ratio of steelmaking slag to fly ash of 1.5:1 to 1:2, more preferably 1.3:1 to 1:1.

5.

3. The cement-based binder according to claim 1, wherein the first aluminosilicate is steelmaking slag, and a further aluminosilicate is selected from class F fly ash and / or calcined clay according to ASTM C618.

4. The cement-based binder according to claim 1, comprising two chemically distinct aluminosilicates selected from steelmaking slag, particularly granulated blast furnace slag powder, and clay minerals, preferably calcined clay, particularly metakaolin.

5. The cement-based binder according to any one of claims 1 to 4, wherein the cement-based binder further comprises 5 to 15% by weight, preferably 6 to 8% by weight, of silica fume based on the total dry weight of the cement-based binder.

6. The cement-based binder according to any one of claims 1 to 4, wherein the weight ratio of ordinary Portland cement to the total of at least two heat-activated aluminosilicates is 0.1 to 2, preferably 0.3 to 2, and more preferably 0.6 to 1.

6.

7. The cement-based binder according to claim 1, comprising silica fume, calcined clay, and class F fly ash according to ASTM C618, wherein the weight ratio of the total silica fume and calcined clay to the fly ash is 0.1 to 0.

5.

8. The cement-based binder according to any one of claims 2 to 4, wherein the steelmaking slag is water-granulated blast furnace slag powder.

9. The cement-based binder according to any one of claims 1 to 4, wherein the calcium sulfate source is anhydrous gypsum.

10. A geopolymer composition, (a) The cement-based binder described in claim 1, (b) Aggregates and / or fillers, (c) Further additives may be optionally selected, A geopolymer composition containing [the specified element].

11. A method for repairing concrete or mortar structures or masonry, wherein the above method comprises the following steps: (a) To provide a cement-based binder according to any one of claims 1 to 4, or a geopolymer composition according to claim 10, (b) Mixing the cement-based binder or the geopolymer composition provided in step (a) with water, (c) Apply the mixture obtained in step (b) to the surface of a hardened concrete or mortar structure, (d) Optionally, curing the applied mixture, Methods that include...

12. A method for protecting a structure, particularly a concrete or mortar structure or a masonry structure, wherein the method comprises the following steps: (a) To provide a cement-based binder according to any one of claims 1 to 4, or a geopolymer composition according to claim 10, (b) Mixing the cement-based binder or the geopolymer composition provided in step (a) with water, (c) Apply the mixture obtained in step (b) to the surface of the hardened structure, (d) Optionally, curing the applied mixture, Methods that include...

13. A waterproofing method for structures, particularly concrete or mortar structures or masonry structures, wherein the method comprises the following steps: (a) To provide a cement-based binder according to any one of claims 1 to 4, or a geopolymer composition according to claim 10, (b) Mixing the cement-based binder or the geopolymer composition provided in step (a) with water, (c) Apply the mixture obtained in step (b) to the surface of the hardened structure, (d) Optionally, curing the applied mixture, Methods that include...

14. A 3D printing method for a mortar composition, wherein the method comprises the following steps: (a) A step of providing a cement-based binder according to any one of claims 1 to 4, or a geopolymer composition according to claim 10, (b) Mixing the cement-based binder or the geopolymer composition provided in step (a) with water, (c) Optionally, the mixture obtained in step (b) is transferred to a print head, preferably a print head mounted on a movable arm. (c) Applying the mixture obtained in step (b) layer by layer from the print head to form a three-dimensional object, (d) By choice, harden the three-dimensional object, Methods that include...

15. A shot cleaning method, wherein the above method comprises the following steps: (a) To provide a cement-based binder according to any one of claims 1 to 4, or a geopolymer composition according to claim 10, (b) Mixing the cement-based binder or the geopolymer composition provided in step (a) with water, (c) Transferring the mixture obtained in step (b) to the gun, (d) Optionally, adding an additional accelerator to the mixture obtained in step (b), (c) spraying the mixture from the gun into the gaps and / or onto the surface, (d) Optionally, curing the applied mixture, Methods that include...

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