Composition of shotcrete, process and structure of hardened shotcrete

Abstract

The invention relates to a process comprising a shotcrete composition, process and hardened shotcrete structure. A shotcrete composition comprising a) a cement binder; b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; and c) an alkali-free aluminum-based shotcrete accelerator. The invention further relates to a process comprising providing a cement composition comprising a) a cement binder and b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; mixing an alkali-free aluminum-based shotcrete accelerator with the cement composition to obtain a shotcrete composition; and applying the shotcrete composition to a surface to obtain a shotcrete structure and enabling the shotcrete structure to harden.The invention also relates to a hardened sprayed concrete structure obtained by this process.

Description

1 / 40 COMPOSITION OF SHOTCRETE, PROCESS AND STRUCTURE OF HARDENED SHOTCRETE

[001] The present invention relates to a sprayed concrete composition and a method for its application.

[002] Shotcrete (or sprayed concrete) is a mortar or concrete product that is transported from distribution equipment via, for example, a hose, and pneumatically projected at high speed onto a surface. It has been used to protect exposed rocks from degradation due to disintegration and deposition, as well as to provide support for loose rock blocks in broken or overstressed soils. Typically, additives are introduced into the cement / aggregate mixture to improve its physical properties.

[003] In mining applications, the aim is to reduce the time spent preparing excavations, shafts, or tunnels to increase the productivity of the structure without compromising worker safety. In open excavations, when an elevator is removed and as the newly exposed soil has a limited support time, shotcrete is sprayed first for stabilization, and then rock bolts or some other means of support are installed for permanent support. In tunnel excavation and mining, the exposed face is often sprayed with shotcrete until the next round is prepared for blasting. Additionally, the tunnel surface is often sprayed with shotcrete until rock bolts or steel rings or segmental concrete linings can be installed.

[004] Conventional shotcrete can cure in just a few minutes, but it is relatively slow to harden, taking several days to reach most of its strength. This means there is a significant delay after the shotcrete has been sprayed while Petition 870230082677, dated 09 / 18 / 2023, page 8 / 62 2 / 40 of the time it hardens until it is safe to resume mining activities in the vicinity of the shotcrete. This delay depends on what is considered an acceptable strength that the concrete needs to achieve. This delay slows down mining operations and limits the applications in which shotcrete can be used. The delay can be minimized by using a shotcrete mix that hardens quickly and develops high early strengths. Especially in difficult working conditions, such as unstable soil where rapid advance rates are required, or if thick layers have to be sprayed high up, the high early strength of shotcrete is crucial.

[005] Wang et al., Materials 2019, 12, 20133, “Comparison of Effects of Sodium Bicarbonate and Sodium Carbonate on the Hydration and Properties of Portland Cement Paste”, discuss sodium carbonates and bicarbonates as accelerators for sprayed concrete.

[006] Another problem in the manufacture of shotcrete is the trade-off between setting time and initial strength development, and the pumpability and sprayability of the shotcrete. Improving the pumpability and sprayability of shotcrete will minimize energy consumption and the risk of blockages.

[007] Furthermore, there is a desire to provide shotcrete that has reduced influence of low temperatures on strength development and is therefore suitable, for example, for use in winter construction.

[008] WO 2017 / 212045 A1 describes construction chemical compositions comprising a glyoxylic acid bisulfite adduct or salts thereof and an inorganic binder. The composition is described as advantageously affecting the properties of mortar, such as open time, processability, setting and compressive strength.

[009] There is a need for shotcrete compositions with high compressive strength a few hours after the curing time, without Petition 870230082677, dated 09 / 18 / 2023, page 9 / 62 3 / 40 compromise its pumping and spraying capacity or even have improved pumping and spraying capacity. Furthermore, there is a need for shotcrete compositions that are suitable for shotcrete in colder conditions.

[010] The above problems are solved by a shotcrete composition comprising a) a cement binder; b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; and c) an alkali-free, aluminum-based engineered concrete accelerator.

[011] The invention also relates to a process comprising - to provide a cement composition comprising a) a cement binder and b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; - Mix an alkali-free, aluminum-based shotcrete accelerator into the cement mix to obtain a shotcrete mix; and - Apply the sprayed concrete mix to a surface to create a sprayed concrete structure and allow the sprayed concrete structure to harden.

[012] In some forms, the shotcrete structure is in the form of a shotcrete layer.

[013] The invention further relates to a hardened shotcrete structure obtained by the process mentioned above.

[014] After the hydration of a cement system, ettringite is generated in a rapid reaction. Ettringite is a compound of aluminum and calcium sulfate with the formula Ca6Ab(SO4)3 * 32 H2O or, alternatively, 3 CaO * Al2O3 * 3 CaSO4 * 32 H2O. This reaction is responsible for Petition 870230082677, dated 09 / 18 / 2023, page 10 / 62 4 / 40 Development of early compressive strength of the cement composition. Ettringite forms as long, needle-shaped crystals. The newly formed small, needle-like ettringite crystals, however, tend to deteriorate the workability or flowability of the cement composition. Furthermore, ettringite contains 32 moles of water in its stoichiometric formula. This means that after ettringite formation, a significant amount of water is bound to the solid crystals, and the flowability of the composition is reduced.

[015] According to the invention, an ettringite formation controller is added to the composition in order to retard the reaction and improve workability. The controller retards the onset of hydration by inhibiting the dissolution of reactive cement components, in particular aluminates, and / or by masking calcium ions, thus slowing down the hydration reaction.

[016] According to the invention, the ettringite formation controller comprises (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct. The glyoxylic acid condensate or glyoxylic acid adduct is believed to suppress ettringite formation from aluminate phases originating from the cement binder by stabilizing the aluminate phases and thus delaying the dissolution of the aluminate phases.

[017] In one embodiment, the glyoxylic acid condensate is an amine-glyoxylic acid condensate. The term amine-glyoxylic acid condensate is intended to mean a glyoxylic acid condensate with a compound containing amino or amide groups reactive with aldehydes. Examples of compounds containing amino or amide groups reactive with aldehydes include urea, thiourea, melamine, guanidine, acetoguanamine, benzoguanamine and other acylguanamines and polyacrylamide.

[018] Preferably, the amine-glyoxylic acid condensate is a melamine-glyoxylic acid condensate, a urea-glyoxylic acid condensate, a melamine-urea-glyoxylic acid condensate and / or a Petition 870230082677, dated 09 / 18 / 2023, page 11 / 62 5 / 40 polyacrylamide-glyoxylic acid condensate. Urea-glyoxylic acid condensates are particularly preferred.

[019] Glyoxylic acid-amine condensates are obtained by reacting glyoxylic acid with a compound containing aldehyde-reactive amino or amide groups. Glyoxylic acid can be used as an aqueous solution or as glyoxylic acid salts, preferably alkali metal salts of glyoxylic acid. Similarly, the amine compound can be used as a salt, for example, as guanidinium salts. In general, the amine compound and glyoxylic acid are reacted at a molar ratio of 0.5 to 2 equivalents, preferably 1 to 1.3 equivalents, of glyoxylic acid per aldehyde-reactive amino or amide group. The reaction is carried out at a temperature of 20 to 120 °C, preferably 25 to 80 °C. The pH value is from 0 to 7. The viscous products obtained in the reaction can be used as such, adjusted to a desired solids content by dilution or concentration, or evaporated to dryness, for example, by drum drying or flash drying.

[020] In general, amine-glyoxylic acid condensates have molecular weights in the range of 500 to 25,000 g / mol, preferably 1,000 to 10,000 g / mol, particularly preferably 1,000 to 5,000 g / mol.

[021] In one embodiment, the glyoxylic acid adduct is a glyoxylic acid bisulfite adduct, or a salt or a mixed salt thereof. The term glyoxylic acid bisulfite adduct is intended to mean a glyoxylic acid adduct with a sulfur- and oxygen-containing compound capable of adding a bisulfite equivalent, i.e., hydrogen sulfide (HSO3), to glyoxylic acid.

[022] Preferably, the bisulfite adduct has the general formula (I) OH M1OOC—CH SO3M1(|)where Petition 870230082677, dated 09 / 18 / 2023, page 12 / 62 6 / 40 M1 is independently selected from H or an equivalent cation Kr, where K is selected from an alkali metal, alkaline earth metal, zinc, copper, iron, aluminum, ammonium or phosphonium cation, or mixtures thereof, er is 1 / v, where v is the valence of the cation.

[023] If M1 is a Kr cation equivalent, the resulting compound is a salt that also includes mixed salts. In a further embodiment, the salt is selected from an alkali metal, alkaline earth metal, zinc, copper, iron, aluminum, ammonium or phosphonium salt, preferably from an alkali metal salt, such as sodium or potassium salt.

[024] Bisulfite adducts are commercially available or can be prepared by conventional methods known to those skilled in the art. See, for example, WO 2017 / 212045 A1 for more details in this regard.

[025] In a preferred embodiment, the ettringite formation controller further comprises (ii) a carbonate source. Components (i) and (ii) have been found to act synergistically. The presence of the carbonate source ensures that the mixing water is initially highly concentrated in carbonate ions. The carbonate ions are believed to inhibit ettringite crystallization. The carbonate source can be an inorganic carbonate with an aqueous solubility of 0.1 gL-1 or more. The aqueous solubility of the inorganic carbonate is determined in water at pH 7 and 20 °C. These characteristics are well known to those skilled in the art.

[026] Inorganic carbonate is intended to mean a salt of carbonic acid, that is, a salt that is characterized by the presence of a carbonate ion (CO32-) and / or hydrogen carbonate ion (HCO3-).

[027] Inorganic carbonate can be suitably selected from alkali metal carbonates, such as sodium carbonate or lithium carbonate, and alkaline earth metal carbonates that satisfy the required aqueous solubility, such as magnesium carbonate. Petition 870230082677, dated 09 / 18 / 2023, page 13 / 62 7 / 40 Additional suitable inorganic carbonates include nitrogen-based carbonates, such as guanidinium carbonate and ammonium carbonate.

[028] Alternatively, the carbonate source is selected from organic carbonates. Organic carbonate denotes an ester of carbonic acid. The organic carbonate is hydrolyzed in the presence of the cement system to release carbonate ions. In one embodiment, the organic carbonate is selected from ethylene carbonate, propylene carbonate, glycerol carbonate, dimethyl carbonate, di(hydroxyethyl)carbonate or a mixture thereof, preferably ethylene carbonate, propylene carbonate and glycerol carbonate or a mixture thereof, and in particular ethylene carbonate and / or propylene carbonate. Mixtures of inorganic carbonates and organic carbonates may also be used.

[029] The weight ratio of component (i) to component (ii) is normally in the range of about 10:1 to about 1:10, preferably about 5:1 to about 1:5 or about 1:1 to about 1:4.

[030] In one embodiment, the ettringite formation controller further comprises (iii) a component selected from - polycarboxylic acids or salts thereof with a milliequivalent number of carboxyl groups of 5.00 meq / g or higher, preferably 5.00 to 15.00 meq / g, assuming that all carboxyl groups are in the non-neutralized form; and - α-hydroxycarboxylic acids or salts thereof.

[031] The term polycarboxylic acid, as used in this document, means a compound or polymer with two or more carboxyl groups in the molecule.

[032] Suitable polycarboxylic acids are - Low molecular weight polycarboxylic acids (with a molecular weight of, for example, 500 g / mol or less), in particular aliphatic polycarboxylic acids, such as oxalic acid, malonic acid, Petition 870230082677, dated 09 / 18 / 2023, page 14 / 62 8 / 40 succinic acid, glutaric acid, adipic acid, pimelic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid or malic acid; - phosphonoalkylcarboxylic acids, such as 1-phosphonobutane-1,2,4-tricarboxylic acid, 2-phosphonobutane-1,2,4tricarboxylic acid, 3-phosphonobutane-1,2,4-tricarboxylic acid, 4phosphonobutane-1,2,4-tricarboxylic acid, 2,4-diphosphonobutane-1,2,4tricarboxylic acid, 2-phosphonobutane-1,2,3,4-tetracarboxylic acid, 1-methyl-2phosphonopentane-1,2,4-tricarboxylic acid or 1,2-phosphonoethane-2dicarboxylic acid; - aminocarboxylic acids, such as ethylenediaminetetraacetic acid or nitrilotriacetic acid; - Polymeric carboxylic acids, such as acrylic acid homopolymers, methacrylic acid homopolymers, polymaleic acid, copolymers such as ethylene / acrylic acid copolymer and ethylene / methacrylic acid copolymer; acrylic acid and / or methacrylic acid copolymers with sulfo- or sulfonate-containing monomers. In one embodiment, the sulfo- or sulfonate-containing monomers are selected from the vinylsulfonic acid, (methyl)allylsulfonic acid, 4-vinylphenylsulfonic acid or 2-acrylamido-2-methylpropylsulfonic acid (ATBS) group, with ATBS being particularly preferred. It is possible that one or more of the sulfo- or sulfonate-containing monomers mentioned above are contained in the copolymers.

[033] In general, the molecular weight of polymeric carboxylic acids is in the range of 1,000 to 30,000 g / mol, preferably from 1,000 to 10,000 g / mol.

[034] Suitable α-hydroxycarboxylic acids or salts thereof include tartaric acid, citric acid, glycolic acid, gluconic acid and their salts and mixtures thereof. Sodium gluconate is particularly preferred. Petition 870230082677, dated 09 / 18 / 2023, p. 15 / 62 9 / 40

[035] The weight ratio of component (i) to component (ii) is normally in the range of about 10:1 to about 1:10, preferably about 5:1 to about 1:5 or about 3:1 to about 1:1.

[036] Preferably, the dosage of (i), or the sum of (i) and (ii), or the sum of (i), (ii) and (iii) is 0.05 to 3%, preferably 0.1 to 1%, relative to the weight of the cement binder.

[037] The ettringite formation controller may be present as a solution or dispersion, in particular an aqueous solution or dispersion. The solution or dispersion suitably has a solids content of 10 to 50% by weight, in particular 25 to 35% by weight. Alternatively, the ettringite formation controller may be present as a powder which may be obtained, for example, by drum drying, spray drying or quick drying. The ettringite formation controller may be introduced into the mixing water or introduced during the mixing of the mortar or concrete before the addition of water.

[038] The weight ratio of ettringite forming controller (b) to cement binder (a) in the mix of shotcrete is normally in the range of about 0.05 to about 10%, preferably about 0.1 to about 4% or about 0.2 to about 3%.

[039] Typically, a cement composition is provided comprising a) the cement binder and b) the ettringite formation controller as defined above. The cement composition may comprise additional ingredients that are conventional in the art and are exemplified below. The cement composition is mixed with water. The cement composition mixed with water is also referred to as cement paste.

[040] An alkali-free, aluminum-based shotcrete accelerator is mixed into the cement mix to obtain the shotcrete mix. In accordance with European regulations (PREN 934-5 Petition 870230082677, dated 09 / 18 / 2023, page 16 / 62 10 / 40 Admixtures for Sprayed Concrete - Definitions, Requirements, Conformity, Marking and Labeling (Aditivos para Concreto Pulverizado - Definições,requisitos, Conformidade, Marcação e Rotulagem)), an accelerator is classified as “alkali-free” when the concentration of sodium and potassium, expressed as Na2O equivalents, is less than 1%. Lithium is also an alkali metal; however, scientific literature shows that it does not negatively affect concrete and is therefore not considered in the calculation of Na2O equivalents. Alkali-free accelerators may include alkaline earth metal compounds, such as calcium salts, magnesium salts, and mixtures thereof.

[041] Typically, alkali-free aluminum-based shotcrete accelerator is included in a shotcrete accelerator formulation for ease of handling. In addition to the alkali-free aluminum-based shotcrete accelerator, the shotcrete accelerator formulation contains additives to provide shelf stability and other desirable properties for the shotcrete accelerator formulation. The shotcrete accelerator formulation may be in liquid or solid form, such as powder form.

[042] As shown in the examples in this document, the use of alkali-free accelerators has significant advantages over alkali-containing accelerators with respect to the early strength of shotcrete compositions. In addition, the disadvantages associated with the presence of alkali-containing accelerators can be avoided.

[043] In particular, sprayed concrete accelerators containing alkalis, such as alkali metal aluminates, alkaline earth metal aluminates, alkali metal silicates, alkaline earth metal silicates and mixtures thereof, can negatively affect long-term mechanical strength. Furthermore, due to their alkaline nature, they are Petition 870230082677, dated 09 / 18 / 2023, page 17 / 62 11 / 40 Irritants to the skin and contact with the eyes should be strictly avoided. Therefore, special protective devices are required for worker safety. Furthermore, alkaline metal substances react with aggregates and can promote the reaction of alkaline silica, which impairs the properties of concrete. Additionally, when the alkaline content in shotcrete is too high, it can lead to corrosion of steel reinforcements. Finally, shotcrete accelerators containing alkalis release alkaline substances which, by increasing the pH of groundwater, can be dangerous pollutants.

[044] The alkali-free accelerators of the compositions of the invention are based on aluminum compounds, for example, aluminum salts, such as sulfates, nitrates, fluorides and / or their hydrates; aluminum oxides; and aluminum hydroxides. The alkali-free accelerators can be selected from aluminum salts, aluminum complexes, aluminum oxides, aluminum hydroxides and mixtures thereof. Preferably, the alkali-free accelerator is selected from aluminum salts, especially aluminum sulfates.

[045] The weight ratio of cement binder (a) to alkali-free aluminum-based shotcrete accelerator (c) in the shotcrete mix is ​​normally in the range of about 1,000:1 to about 3:1, preferably about 100:1 to about 10:1 or about 35:1 to about 5:1.

[046] Alkaline-free sprayed concrete accelerator formulations can be stabilized by various chemicals. Examples of such stabilizers include organic acids, such as carboxylic acids, dicarboxylic acids, hydroxycarboxylic acids, aminocarboxylic acids, phosphoric acid, phosphorous acid, phosphonic acids, sulfamic acid; inorganic acids, such as sulfuric acid, nitrous acid, phosphoric acid, phosphorous acid, hydrofluoric acid, hexafluorosilicic acid and mixtures thereof; urea; polymeric stabilizers, such as Petition 870230082677, dated 09 / 18 / 2023, page 18 / 62 12 / 40 polyacrylamides, polycarboxylates, polysulfonates and copolymers and mixtures thereof; aluminosilicates, such as attapulgite, sepiolite and bentonite; and colloidal silica. In addition, sprayed concrete accelerators may further comprise calcium and magnesium compounds, such as, for example, sulfates, as well as amines, for example, alkanolamines, such as diethanolamine, triethanolamine, diisopropanolamine and triisopropanolamine and mixtures thereof.

[047] Suitable alkali-free accelerators and their manufacture are described, for example, in WO 2008 / 006410 A1, WO 2010 / 063777 A1, WO 98 / 18740 A1, WO 03 / 029163 A2 and EP 1 167 317 A1.

[048] Preferably, the shotcrete composition according to the invention further comprises at least one dispersant for inorganic binders, especially a dispersant for cement mixtures such as concrete or mortar. Preferably, the dispersant is included in the cement composition before mixing the alkali-free aluminum-based shotcrete accelerator.

[049] Examples of useful dispersants include - comb polymers with a carbon-containing main chain to which are attached pendant cement anchoring groups and polyether side chains, - non-ionic comb polymers with a carbon-containing back chain to which pendant hydrolyzable groups and polyether side chains are attached, the hydrolyzable groups after hydrolysis releasing cement-anchoring groups, - sulfonated melamine-formaldehyde condensates, - lignosulfonates, - sulfonated ketone-formaldehyde condensates, - sulfonated haphthalene-formaldehyde condensates, - dispersants containing phosphonate, - dispersants containing phosphate, and Petition 870230082677, dated 09 / 18 / 2023, page 19 / 62 13 / 40 mixtures of these.

[050] In one embodiment, the dispersant is a comb polymer with a carbon-containing back chain to which are attached pendant cement anchoring groups and polyether side chains. The cement anchoring groups are anionic and / or anionogenic groups, such as carboxylic groups, phosphonic or phosphoric acid groups or their anions. Anionogenic groups are the acidic groups present in the polymeric dispersant, which can be transformed into the respective anionic group under alkaline conditions.

[051] Preferably, the structural unit comprising anionic and / or anionogenic groups is one of the general formulas (Ia), (Ib), (Ic) and / or (Id): H R1_μ μ ' II ' HC=OIX R2 I was in which R1 is H, C1-C4 alkyl, CH2COOH or CH2CO-X-R3A, preferably H or methyl; X is NH-(CniH2ni) or O-(CniH2ni) with n1= 1, 2, 3 or 4, or a chemical bond, the nitrogen atom or the oxygen atom being bonded to the CO group; R2 is OM, PO3M2 or O-PO3M2; with the condition that X is a chemical bond if R2 is OM; R3Aé PO3M2ou O-PO3M2; H R3 / II x -4—cc—μ1 1 ?4 H (CnH2n)-R4 Petition 870230082677, dated 09 / 18 / 2023, p. 20 / 62 14 / 40 lb in which R3 is H or C1-C4 alkyl, preferably H or methyl; n is 0, 1, 2, 3 or 4; R4é PO3M2 or O-PO3M2; z Ic in which R5 is H or C1-C4 alkyl, preferably H; Z is O or NR7; R7 is H, (CnlH2nl)-OH, (CnlH2nl)-PO3M2, (CniH2ni)-OPO3M2, (C6H4)PO3M2 or (CeH4)-OPO3M2, and n1 is 1, 2, 3 or 4; H R6 / IH —HC— ' II;o=cc=o Q OM R' ID in which R6 is H or C1-C4 alkyl, preferably H; Q is NR7 or O; R7 is H, (CnlH2nl)-OH, (CnlH2nl)-PO3M2, (CniH2ni)-OPO3M2, (C6H4)PO3M2 or (CeH4)-OPO3M2, n1 is 1, 2, 3 or 4; and where each M, independently, is H or an equivalent cation. Petition 870230082677, dated 09 / 18 / 2023, p. 21 / 62 15 / 40

[052] Preferably, the structural unit comprising a polyether side chain is one of the general formulas (Ila), (lib), (He) and / or (IId): R10R11 R12c„2H2.I2-ze-gHao;vr'3 There is in which R10, R11 and R12, independently of each other, are H or C1-C4 alkyl, preferably H or methyl; Z2 is O or S; E is C2-C6 alkylene, cyclohexylene, Chh-CeHio, 1,2-phenylene, 1,3phenylene or 1,4-phenylene; G is O, NH, or CO-NH; or E and G, together, form a chemical bond; A is C2-C5 alkylene or ChhChKCeHs), preferably C2-C3 alkylene; n2 is 0, 1, 2, 3, 4 or 5; a is an integer from 2 to 350, preferably from 10 to 150, more preferably from 20 to 100; R13 is H, an unbranched or branched C1-C4 alkyl group, CONH2 or COCH3; R16R17 R18(Cn2H2n2)-O-E2-N-(AO)a-R19(LO)d-R20llb where R16, R17 and R18, independently of each other, are H or C1-C4 alkyl, preferably H; Petition 870230082677, dated 09 / 18 / 2023, p. 22 / 62 16 / 40 E2 is C2-C6 alkylene, cyclohexylene, CH2-C6H10, 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, or it is a chemical bond; A is C2-C5 alkylene or ChhChKCeHs), preferably C2-C3 alkylene; n2 is 0, 1, 2, 3, 4 or 5; L is C2-C5 alkylene or ChhChKCeHs), preferably C2-C3 alkylene; a is an integer from 2 to 350, preferably from 10 to 150, more preferably from 20 to 100; d is an integer from 1 to 350, preferably from 10 to 150, more preferably from 20 to 100; R19 is H or C1-C4 alkyl; and R20 is H or C1-C4 alkyl; Γ- „21 „22 - RR --C---CT|a|T r R C---W--(AO)a The LLC in which R21, R22 and R23, independently, are H or C1-C4 alkyl, preferably H; W is O, NR25 or is N; V is1 if W= O or NR25, eé2ifW=N; A is C2-C5 alkylene or ChhChKCeHs), preferably C2-C3 alkylene; a is an integer from 2 to 350, preferably from 10 to 150, more preferably from 20 to 100; R24 is H or C1-C4 alkyl; R25 is H or C1-C4 alkyl; Petition 870230082677, dated 09 / 18 / 2023, p. 23 / 62 17 / 40 lid in which R6 is H or C1-C4 alkyl, preferably H; Q is NR10, NouO; V is 1 if Q = 0 or NR10, and is 2 if Q = N; R10 is H or C1-C4 alkyl; A is C2-C5 alkylene or ChhChKCeHs), preferably C2-C3 alkylene; and a is an integer from 2 to 350, preferably from 10 to 150, more preferably from 20 to 100; where each M, independently, is H or an equivalent cation.

[053] The molar ratio of structural units (I) to structural units (II) varies from 1:3 to about 10:1, preferably from 1:1 to 10:1, more preferably from 3:1 to 6:1. Polymeric dispersants comprising structural units (I) and (II) can be prepared by conventional methods, for example, by free radical polymerization. The preparation of dispersants is, for example, described in EP 0 894 811, EP 1 851 256, EP 2 463 314 and EP 0 753 488.

[054] Several useful dispersants contain carboxyl groups, salts thereof, or hydrolyzable groups that release carboxyl groups upon hydrolysis. Preferably, the milliequivalent number of carboxyl groups contained in these dispersants (or of carboxyl groups releaseable upon hydrolysis of hydrolyzable groups contained in the dispersant) is 4.90 meq / g or less, assuming that all carboxyl groups are in the unneutralized form.

[055] More preferably, the dispersant is selected from the group of polycarboxylate ethers (PCEs). In PCEs, the anionic groups Petition 870230082677, dated 09 / 18 / 2023, page 24 / 62 18 / 40 are carboxylic and / or carboxylate groups. PCE is preferably obtained by radical copolymerization of a polyether macromonomer and a monomer comprising anionic and / or anionogenic groups. Preferably, at least 45 mol%, preferably at least 80 mol%, of all structural units constituting the copolymer are structural units of the polyether macromonomer or the monomer comprising anionic and / or anionogenic groups.

[056] An additional class of suitable comb polymers with a carbon-containing main chain to which pendant cement anchoring groups and polyether side chains are attached comprise structural units (III) and (IV): III in which T is phenyl, naphthyl, or heteroaryl with 5 to 10 atoms in the ring, of which 1 or 2 atoms are heteroatoms selected from N, O, and S; n3 is 1 or 2; B is N, NH, or O, with the condition that n3 is 2 if B is N, and n3 is 1 if B is NH or O; A is C2-C5 or CH2CH(C6Hs) alkylene, preferably C2-C3 alkylene; a2 is an integer from 1 to 300; R26 is H, C1-C10 alkyl, Cs-Cs cycloalkyl, aryl or heteroaryl with 5 to 10 atoms in the ring, of which 1 or 2 atoms are heteroatoms selected from N, O and S; The structural unit (IV) is selected from structural units (IVa) and (IVb): Petition 870230082677, dated 09 / 18 / 2023, p. 25 / 62 19 / 40 I OF IVa OM in which D is phenyl, naphthyl, or heteroaryl with 5 to 10 atoms in the ring, of which 1 or 2 atoms are heteroatoms selected from N, O, and S; E3 is N, NH, or O, with the condition that m is 2 if E3 is N and em is 1 if E3 is NH or O; A is C2-C5 or CH2CH(C6Hs) alkylene, preferably C2-C3 alkylene; b is an integer from 0 to 300; M is either H or an equivalent cation; V2----r7A IVb in which V2 is phenyl or naphthyl and is optionally replaced by one or two radicals selected from R8, OH, OR8, (CO)R8, COOM, COOR8, SO3R8 and NO2; R7A is COOM, OCH2COOM, SO3M or OPO3M2; M is H or an equivalent cation; and R8 is C1-C4 alkyl, phenyl, naphthyl, phenyl-C1-C4 alkyl or C1-C4 alkylphenyl.

[057] Polymers comprising structural units (III) and (IV) are obtained by polycondensation of an aromatic or heteroaromatic compound with a polyoxyalkylene group attached to the aromatic or heteroaromatic core, an aromatic compound with a carboxylic, sulfonic or phosphate moiety and an aldehyde compound, such as formaldehyde. Petition 870230082677, dated 09 / 18 / 2023, p. 26 / 62 20 / 40

[058] In one embodiment, the dispersant is a nonionic comb polymer with a carbon-containing back chain to which pendant hydrolyzable groups and polyether side chains are attached, the hydrolyzable groups after hydrolysis releasing cement anchoring groups. Conveniently, the structural unit comprising a polyether side chain is one of the general formulas (Ila), (lib), (llc) and / or (lld) discussed above. The structural unit with pendant hydrolyzable groups is preferably derived from acrylic acid ester monomers, more preferably hydroxyalkyl acrylic monoesters and / or hydroxyalkyl diesters, more preferably hydroxypropyl acrylate and / or hydroxyethyl acrylate.The ester functionality will hydrolyze into acidic (deprotonated) groups upon exposure to water at a preferably alkaline pH, which is provided by mixing the cement binder with water, and the resulting acidic functional groups will then form complexes with the cement component.

[059] Suitable sulfonated melamine-formaldehyde condensates are of the type frequently used as plasticizers for hydraulic binders (also referred to as MFS resins). Sulfonated melamine-formaldehyde condensates and their preparation are described, for example, in CA 2 172 004 A1, DE 44 1 1 797 A1, US 4,430,469, US 6,555,683 and CH 686 186 and also in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., vol. A2, page 131, and Concrete Admixtures Handbook - Properties, Science and Technology, 2nd Ed., pages 411, 412. Preferred sulfonated melamine-formaldehyde condensates encompass (extremely simplified and idealized) units of the formula i2SO3Na+ Petition 870230082677, dated 09 / 18 / 2023, page 27 / 62 21 / 40 where n4 generally means 10 to 300. The molar weight is preferably in the range of 2,500 to 80,000. In addition to sulfonated melamine units, other monomers can be incorporated by condensation. Urea is particularly suitable. Furthermore, additional aromatic units can also be incorporated by condensation, such as gallic acid, aminobenzenesulfonic acid, sulfanilic acid, phenolsulfonic acid, aniline, ammoniobenzoic acid, dialkoxybenzenesulfonic acid, dialkoxybenzoic acid, pyridine, pyridinemonosulfonic acid, pyridinedisulfonic acid, pyridinecarboxylic acid and pyridinedicarboxylic acid. An example of melaminesulfonate-formaldehyde condensates are the Melment® products distributed by BASF Construction Solutions GmbH.

[060] Suitable lignosulfonates are products obtained as byproducts in the paper industry. They are described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., vol. A8, pages 586, 587. They include units of the highly simplified and idealized formula. OCH, OCH, J w·

[061] Lignosulfonates have molar weights between 2,000 and 100,000 g / mol. In general, they are present in the form of their sodium, calcium and / or magnesium salts. Examples of suitable lignosulfonates are the Borresperse products distributed by Borregaard LignoTech, Norway. Petition 870230082677, dated 09 / 18 / 2023, page 28 / 62 22 / 40

[062] Suitable sulfonated ketone-formaldehyde condensates are products incorporating a monoketone or diketone as a ketone component, preferably acetone, butanone, pentanone, hexanone, or cyclohexanone. Condensates of this type are known and are described in WO 2009 / 103579, for example. Sulfonated acetone-formaldehyde condensates are preferred. They generally comprise units of the formula (according to J. Plank et al., J. Appl. Poly. Sci. 2009, 2018-2024): where m2 and n5 are generally each from 10 to 250, M2 is an alkali metal ion, such as Na+, and the m2:n5 ratio is generally in the range of about 3:1 to about 1:3, more particularly about 1.2:1 to 1:1.2. Furthermore, it is also possible for other aromatic units to be incorporated by condensation, such as gallic acid, aminobenzenesulfonic acid, sulfanilic acid, phenolsulfonic acid, aniline, ammoniobenzoic acid, dialkoxybenzenesulfonic acid, dialkoxybenzoic acid, pyridine, pyridinemonosulfonic acid, pyridinedisulfonic acid, pyridinecarboxylic acid and pyridinedicarboxylic acid. Examples of suitable sulfonated acetone-formaldehyde condensates are the Melcret K1L products distributed by BASF Construction Solutions GmbH.

[063] Suitable sulfonated naphthalene-formaldehyde condensates are products obtained by sulfonation of naphthalene and subsequent polycondensation with formaldehyde. They are described in references including Concrete Admixtures Handbook - Properties, Science and Technology, 2nd ed., pages 411-413 and in Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Vol. A8, pages 587, 588. They comprise units of the formula Petition 870230082677, dated 09 / 18 / 2023, page 29 / 62 23 / 40

[064] Typically, molar weights (Mw) between 1,000 and 50,000 g / mol are obtained. In addition, it is also possible for other aromatic units to be incorporated by condensation, such as gallic acid, aminobenzenesulfonic acid, sulfanilic acid, phenolsulfonic acid, aniline, ammoniobenzoic acid, dialkoxybenzenesulfonic acid, dialkoxybenzoic acid, pyridine, pyridinemonosulfonic acid, pyridinedisulfonic acid, pyridinecarboxylic acid and pyridinedicarboxylic acid. Examples of suitable sulfonated β-naphthalene-formaldehyde condensates are the Melcret 500 L products distributed by BASF Construction Solutions GmbH.

[065] Generally, dispersants containing phosphonates incorporate phosphonate groups and polyether side groups.

[066] Suitable phosphonate-containing dispersants are those conforming to the following formula R-(OA2)n6-N-[CH2-PO(OM32)2]2 where R is H or a hydrocarbon residue, preferably a C1-C15 alkyl radical, A2 is, independently, C2-C18 alkylene, preferably ethylene and / or propylene, more preferably ethylene, n6 is an integer from 5 to 500, preferably from 10 to 200, more preferably from 10 to 100 and M3 is H, an alkali metal, half an alkaline earth metal, and / or an amine. Petition 870230082677, dated 09 / 18 / 2023, p. 30 / 62 24 / 40

[067] The cement binder is suitably selected from Portland cement, calcium aluminate cement and / or sulfoaluminate cement.

[068] Mineralogical phases are indicated by their common name followed by their cement notation. Primary compounds are represented in cement notation by the oxide varieties: C for CaO, S for SiO2, A for AbO3, S for SO3, F for Fe2O3, H for H2O; this notation is used everywhere.

[069] The term Portland cement denotes any cementitious compound containing Portland slag, especially CEM I, II, III, IV and V within the meaning of EN 197-1, paragraph 5.2. A preferred cement is ordinary Portland cement (OPC) according to DIN EN 197-1 which may contain calcium sulfate (<7% by weight) or is essentially calcium sulfate-free (<1% by weight). The phases constituting Portland cement are mainly alite (C3S), belite (C2S), calcium aluminate (C3A), calcium ferroaluminate (C4AF) and other minor phases. Alite (C3S) mainly provides strength properties.

[070] Calcium aluminate cement (also known as high aluminate cement) means a cement containing calcium aluminate phases. The term aluminate phase denotes any mineralogical phase resulting from the combination of aluminate (chemical formula Al2O3, or A in cement notation) with other mineral species. The amount of alumina (in the form of AbO3) is > 30% by weight of the total mass of the aluminate-containing cement, as determined by X-ray fluorescence (XRF). More precisely, the said aluminate-type mineralogical phase comprises tricalcium aluminate (C3A), monocalcium aluminate (CA), mayonite (C12A7), tetracalcium aluminoferrite (C4AF), or a combination of several of these phases. Petition 870230082677, dated 09 / 18 / 2023, page 31 / 62 25 / 40

[071] Sulfoaluminate cement has a ye'elimite content (chemical formula 4CaO.3Al2O3.SO3 or C4A3$ in cement notation) greater than 15% by weight.

[072] In one embodiment, the cement binder comprises a mixture of Portland cement and aluminate cement, or a mixture of Portland cement and sulfoaluminate cement, or a mixture of Portland cement, aluminate cement and sulfoaluminate cement.

[073] In one embodiment, where the cement binder contains an aluminate-containing cement, the cement composition may additionally contain at least one source of calcium sulfate. The calcium sulfate source may be selected from calcium sulfate dihydrate, anhydrite, α- and β-hemihydrate, i.e., α-bassanite and β-bassanite, or mixtures thereof. Preferably, the calcium sulfate source is α-bassanite and / or β-bassanite. In general, the calcium sulfate source comprises an amount of about 1 to about 20% by weight, based on the weight of the aluminate-containing cement. In one embodiment, the construction chemical composition additionally contains at least one alkali metal sulfate, such as potassium sulfate or sodium sulfate, or aluminum sulfate.

[074] Shotcrete compositions may also contain latent hydraulic binders and / or pozzolanic binders. Typically, these latent hydraulic binders and / or pozzolanic binders are included in the cement composition before mixing the alkali-free aluminum-based shotcrete accelerator. For the purposes of the present invention, a latent hydraulic binder is preferably a binder in which the molar ratio (CaO + MgO):SiO2 is 0.8 to 2.5 and, particularly, 1.0 to 2.0. In general terms, the aforementioned latent hydraulic binders may be selected from industrial and / or synthetic slag, particularly blast furnace slag, electrothermal phosphorus slag, steel slag and mixtures thereof. Pozzolanic binders may generally be Petition 870230082677, dated 09 / 18 / 2023, pp. 32 / 62 26 / 40 selected from amorphous silica, preferably precipitated silica, pyrogenic silica and microsilica, ground glass, metakaolin, aluminosilicates, fly ash, preferably brown coal fly ash and hard coal fly ash, rice husk ash, natural pozzolans such as tuff, volcanic glass (trass) and volcanic ash, natural and synthetic zeolites and mixtures thereof.

[075] Slag can be industrial slag, that is, waste products from industrial processes, or synthetic slag. The latter can be advantageous because industrial slag is not always available in consistent quantity and quality.

[076] Blast furnace slag (BFS) is a waste product of the glass furnace process. Other materials are granulated blast furnace slag (GBFS) and ground granulated blast furnace slag (GGBFS), which is granulated blast furnace slag that has been finely pulverized. Ground granulated blast furnace slag varies in terms of grinding fineness and grain size distribution, which depend on the origin and treatment method, and grinding fineness influences reactivity here. The Blaine value is used as a parameter for grinding fineness, and typically has an order of magnitude of 200 to 1,000 m2kg-1, preferably 300 to 500 m2kg-1. Finer grinding offers superior reactivity.

[077] For the purposes of the present invention, the term blast furnace slag is intended to encompass materials resulting from all levels of treatment, grinding and quality mentioned (i.e., BFS, GBFS and GGBFS). Blast furnace slag generally comprises 30 to 45% by weight of CaO, about 4 to 17% by weight of MgO, about 30 to 45% by weight of SiO2 and about 5 to 15% by weight of Al2O3, typically about 40% by weight of CaO, about 10% by weight of MgO, about 35% by weight of SiO2 and about 12% by weight of Al2O3.

[078] Electrothermal phosphorus slag is a waste product of electrothermal phosphorus production. It is less reactive than high slag. Petition 870230082677, dated 09 / 18 / 2023, page 33 / 62 Steel slag is a residual product of various steel production processes with a highly variable composition. It is produced in furnaces 27 / 40 and comprises approximately 45 to 50% by weight of CaO, approximately 0.5 to 3% by weight of MgO, approximately 38 to 43% by weight of SiO2, approximately 2 to 5% by weight of Al₂O₃, and approximately 0.2 to 3% by weight of Fe₂O₃, as well as fluoride and phosphate.

[079] Amorphous silica is preferably X-ray amorphous silica, that is, silica for which the powder diffraction method reveals no crystallinity. The SiO2 content in the amorphous silica of the invention is advantageously at least 80% by weight, preferably at least 90% by weight. Precipitated silica is obtained on an industrial scale by means of precipitation processes from liquid glass. The precipitated silica from some production processes is also called silica gel.

[080] Pyrogenic silica is produced by the reaction of chlorosilanes, for example, silicon tetrachloride, in a hydrogen / oxygen flame. Pyrogenic silica is an amorphous SiO2 powder with a particle diameter of 5 to 50 nm and a specific surface area of ​​50 to 600 m2g-1.

[081] Microsilica is a byproduct of silicon or ferrosilicon production and, similarly, consists mainly of amorphous SiO2 powder. The particles have diameters on the order of 0.1 pm. The specific surface area is on the order of 15 to 30 m2g-1.

[082] Fly ash is produced, among other things, during the combustion of coal in central power stations. Class C fly ash (brown coal fly ash) comprises, according to WO 08 / 012438, about 10% by weight of CaO, whereas Class F fly ash (hard coal fly ash) comprises less than 8% by weight, preferably less than 4% by weight and normally about 2% by weight of CaO.

[083] Metakaolin is produced when kaolin is dehydrated. Considering that at 100 to 200 °C kaolin releases physically bound water, Petition 870230082677, dated 09 / 18 / 2023, page 34 / 62 28 / 40 Between 500 and 800 °C, dehydroxylation occurs, leading to the collapse of the lattice structure and the formation of metakaolin (AbSi2O7). Consequently, pure metakaolin comprises approximately 54% by weight of SiO2 and approximately 46% by weight of Al2O3.

[084] For the purposes of the present invention, aluminosilicates are the reactive compounds mentioned above based on SiO2 together with Al2O3 that harden in an aqueous alkaline environment. Obviously, it is not essential here that silicon and aluminum be present in oxide form, as is the case, for example, in Al2Si2O7. However, for purposes of quantitative chemical analysis of aluminosilicates, it is common to state the proportions of silicon and aluminum in oxide form (i.e., as SiO2 and Al2O3).

[085] The cement composition can be, for example, concrete, mortar, or plaster. The term mortar or plaster denotes a cement paste containing fine aggregates, i.e., aggregates whose diameter is between 150 µm and 4 mm (e.g., sand), and optionally very fine granules. A plaster is a mixture of sufficiently low viscosity to fill voids or gaps. The viscosity of mortar is high enough to support not only the weight of the mortar itself, but also that of the masonry placed above it. The term concrete denotes a cement paste containing coarse aggregates, i.e., aggregates with a diameter greater than 4 mm.

[086] The aggregate, in this invention, may be, for example, silica, quartz, sand, crushed marble, glass beads, granite, basalt, sandstone, calcite, marble, serpentine, travertine, dolomite, feldspar, gneiss, alluvial sands, any other durable aggregate and mixtures thereof. The aggregates are often also called fillers and, in particular, do not function as a binder.

[087] The composition of shotcrete may additionally include additives, such as: Petition 870230082677, dated 09 / 18 / 2023, page 35 / 62 29 / 40 - grinding aids, such as amines, amino alcohols, glycols, glycol derivatives, glycerol, glycerol derivatives, molasses, corn syrup; - nucleating agents, such as calcium silicate hydrate compounds in the form of fine grains; - Strength enhancers, such as alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal oxides, alkaline earth metal oxides, alkali metal nitrates, alkaline earth metal nitrates, alkali metal nitrites, alkaline earth metal nitrites, alkali metal thiocyanates, alkaline earth metal thiocyanates, alkali metal halides, alkaline earth metal halides, and alkaline earth metal formates; - setting retarders such as sucrose, glucose, polymeric sugars and phosphonic acids; - Mechanical reinforcement, such as synthetic polymer fibers (e.g., polypropylene), natural fibers, steel fibers, or meshes made from these materials; - Stabilizers or thickeners such as cellulose ethers and cellulose derivatives, starch, starch ethers and other starch derivatives, xanthan gums, Welan gums, diuthan gums, high molecular weight polyacrylamides and copolymers thereof comprising acrylic acid and / or ATBS; - Polymer dispersions in liquid or solid form, such as powder form, like polyacrylates, styrene-butadiene copolymers and ethylene-vinyl acetate copolymers; and - mixtures of these. [ 088] Typically, these additives are included in the cement mix before mixing in the alkali-free, aluminum-based shotcrete accelerator. [ 089] The process according to the invention comprises: Petition 870230082677, dated 09 / 18 / 2023, pp. 36 / 62 30 / 40 - to provide a cement composition comprising a) a cement binder and b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; - Mix an alkali-free, aluminum-based shotcrete accelerator into the cement mix to obtain a shotcrete mix; and - Apply the sprayed concrete mix to a surface to create a sprayed concrete structure and allow the sprayed concrete structure to harden.

[090] Preferably, the shotcrete mix is ​​pneumatically sprayed onto the surface.

[091] In one embodiment, the alkali-free aluminum-based shotcrete accelerator or shotcrete accelerator formulation is mixed into the cement mix using a static mixing device, such as an extruder or a standard sprayed concrete nozzle, or a dynamic mixing device, such as a standard mechanical mixer like a concrete mixer. The shotcrete accelerator formulation may be mixed into the cement mix in the form of an aqueous solution, in the form of an aqueous suspension, in the form of a solid, or in a mixture of these forms.

[092] There are two basic projection technologies to which the present process is applicable: the dry process, in which a mixture of cement, fine and / or coarse aggregates and a powder accelerator is pneumatically conveyed through a nozzle to a distribution hose where water is added through a water ring to the essentially dry materials; and the wet process, in which the cement, aggregates and water are mixed to a plastic consistency before being hydraulically conveyed to the nozzle, where compressed air is added to pneumatically project the wet material. Petition 870230082677, dated 09 / 18 / 2023, page 37 / 62 31 / 40 on the surface. However, there are "mixed" sprayed concrete application technologies.

[093] In one embodiment, the sprayed concrete composition of the invention can be used for 3D printing of various articles, which can be used for construction, decoration and additional purposes.

[094] The invention will be described in more detail by the accompanying drawings and subsequent examples.

[095] Figs. 1a and 1b show the experimental results of mini-drop tests of concrete mixtures.

[096] Figs. 2a and 2b show the experimental results of tests to determine the compressive strength of concrete mixtures.

[097] Figs. 3a and 3b show the experimental results of tests to determine the compressive strength of additional concrete mixtures.

[098] Figs. 4a and 4b show the experimental results of tests to determine the penetration resistance strength of mortar mixtures.

[099] Figs. 5a and 5b show the experimental results of tests to determine the penetration resistance strength of additional mortar mixtures. Examples A.) Materials

[0100] Two types of sprayed cement typical of Germany and In Austria, the following were used: Mergelstetten CEM I 52.5R and a 2:1 (w / w) Eiberg CEMI 52.5N:Fluasit mixed cement (the latter being a mixture of limestone, slag, and fly ash). Both types of cement comprise Portland cement slag and a sulfate source.

[0101] As plasticizers MasterGlenium SKY 594 (further abbreviated as MG SKY 594 or SKY 594) and Melflux 6680L (abbreviated Petition 870230082677, dated 09 / 18 / 2023, pp. 38 / 62 32 / 40 additionally as MF), both available from BASF Construction Solutions GmbH, were used. Both MasterGlenium SKY 594 and Melflux 6680L are polycarboxylate ether (PCE) based plasticizers.

[0102] In the reference mixtures, the hydration control additive MasterRoc HCA 10 (further abbreviated as MR HCA 10 or HCA 10), available from BASF Construction Solutions GmbH, was used. MasterRoc HCA 10 is an aqueous solution of organic acids comprising phosphonic acid and citric acid.

[0103] As MasterRoc pulverized concrete accelerators SA 160 and SA 167, both available from BASF Construction Solutions GmbH, were used. Both MasterRoc SA 160 and SA 167 are alkali-free aqueous suspension-type accelerators based on aluminum sulfate with a solids content in the range of 50±4% and 60±5%, respectively. As reference accelerators, sodium aluminate as an aqueous solution with a solids content of 40% and sodium silicate as an aqueous solution with a solids content of 41.5%, both alkali-containing accelerators, were included in the experiments.

[0104] A glyoxylic acid urea condensate was synthesized as follows: Glyoxylic acid (1.2 g glyoxylic acid, 50% by weight solution in water) was charged into a reaction vessel and aqueous potassium hydroxide (40% by weight) was added until a pH value of 5 was reached. 1 g of urea was added and the mixture was heated to 80 °C. After 7 hours, the highly viscous substance was analyzed by the gel permeation chromatography (GPC) method as described below. The glyoxylic acid urea condensate thus obtained is an aqueous solution with a solids content of 49.3%.

[0105] An ettringite formation controller was prepared according to the following method: Petition 870230082677, dated 09 / 18 / 2023, pp. 39 / 62 33 / 40 BMF: Glyoxylic acid urea condensate was mixed with sodium gluconate and sodium carbonate in a solids / active ingredient weight ratio of 3:1:3. B.) Analytical methods Gel Permeation Chromatography (GPC)

[0106] Combination column: OH-Pak SB-G, OH-Pak SB 804 HQ and OH-Pak SB 802.5 HQ by Shodex, Japan; eluent: 80% by volume of aqueous HCO2NH4 solution (0.05 mol / l) and 20% by volume of acetonitrile; injection volume of 100 µl; flow rate of 0.5 ml / min. Molecular weight calibration was performed with poly(acrylate) standards for the RI detector, acquired from PSS Polymer Standards Service, Germany. C.) Application Tests C. 1) Concrete Tests

[0107] The concrete mixtures were prepared based on the compositions according to the following table. Basic Composition Component B1 B2 Cement (2:1 (w / w) Eiberg CEMI 52.5N:Fluasit) 680 g — Cement (Mergelstetten CEMI 52.5R) — 670 g Standard sand (DIN EN196-1) 1350 g 1350 g Gravel (2-5 mm), washed, limestone-based, DIN EN 12620:2002 900 g 900 g Water (total quantity) 293.9 g 288.1 g

[0108] Eight concrete mixtures were prepared, comprising a base composition as well as the components according to the following table. Concrete Mix C1 C2 C3 C4 * C5 C6 C7 C8 * Base Composition B1 B1 B1 B1 B2 B2 B2 B2 Additional Components [% by weight] Plasticizer (MG SKY 594) ** — — — 0.4 — — — 0.3 Plasticizer (Melflux 6680L) ** 0.025 0.005 0.02 — 0.06 0.005 0.04 — Hydration control additive (MasterRoc HCA 10) *** — — — 0.2 — — — — Petition 870230082677, dated 09 / 18 / 2023, pp. 40 / 62 34 / 40 Ettringite Formation Controller (BMF) ** 1.05 1.75 0.7 — 0.7 1.75 1.05 — * comparative example * * % by weight of the sum of solids of active components in relation to the weight of cement (bwoc) * ** % by weight of aqueous solution in relation to the weight of cement (bwoc)

[0109] Concrete mixtures C1 to C8 were prepared by mixing all components and fall arrest was evaluated. Concrete Mixing Procedure:

[0110] The concrete mix was made in a mixer Hobart dual-action mixer (shaft and planetary) using a 4.7-liter capacity bowl. Sand, gravel, and cement were placed in the bowl and mixed in a dry state at speed 1. Subsequently, 80% of the water was added, and the resulting mixture was mixed at speed 1 for another 2 minutes. After that, an aqueous solution of plasticizer and, if applicable, MasterRoc HCA 10, in the remaining 20% ​​of the water were added, and the mixture was mixed again for 2 minutes at speed 1.

[0111] For mixtures with the ettringite formation controller BMF, a modified mixing procedure was used, in which the plasticizer and the ettringite formation controller are dissolved in 100% of the mixing water for the concrete mix and added all at once after the initial premixing of dry components. The further mixing procedure is the same as in the case mentioned above.

[0112] When the mixture is additionally used for drop retention evaluation, the concrete mixture is transferred to a mini-drop cone (see mini-drop test description below) after a total of 5 minutes of mixing.

[0113] When the mixture is additionally mixed with an accelerator, the mixing speed is changed to speed 2 after a total of 5 minutes and the accelerator is injected into the mixture by means of a Petition 870230082677, dated 09 / 18 / 2023, pp. 41 / 62 35 / 40 syringe as quickly as possible. After 15 seconds of mixing with the accelerator, the mixtures are filled into 4 χ 4 χ 16 cm prism molds, densified on a vibrating table for 30 seconds, sealed with plastic foil and stored at 20 °C, 65% relative humidity, for additional strength measures. Mini-drop test:

[0114] The mini-drop test is a modified concrete drop test for small volumes of concrete, which allows for the accurate prediction of the results of the standardized concrete drop test DIN EN 12350-2. For the mini-drop test, a modified mini-drop cone is used, which represents a “half” of a standard Abrams cone (truncated cone with dimensions of 50, 100 and 150 mm upper inner diameter, lower inner diameter and height). This cone is placed on a flat plate, filled with the fresh concrete mix in two stages of approximately equal volume, and each layer is compacted 15 times. Subsequently, the upper concrete surface is leveled, and then the cone is removed and the drop (difference between the height of the cone and the height of the resulting concrete mound) is recorded.

[0115] This test is repeated as often as necessary (in this case every 15 to 30 min) to assess the slump retention of the mixes. For each repeated slump test, the concrete mix is ​​premixed with a Hobart mixer for 1 minute at speed 1.

[0116] Fig. 1a shows the results of the mini-slump test of concrete mixes C1 to C4. Fig. 1b shows the results of the mini-slump test of concrete mixes C5 to C8. The ettringite controller dosage was varied in both cement types to investigate its effect on slump retention as well as on strength development in the presence of accelerators. The initial slump of the mixes was adjusted to the same initial value when adjusting the plasticizer dosage, in order to allow comparability of the mixes. Petition 870230082677, dated 09 / 18 / 2023, pp. 42 / 62 36 / 40

[0117] It is evident that concrete mixtures comprising the ettringite formation controllers of the invention exhibit a sufficiently long opening time, which can be adjusted to the desired value by varying the dosage of the ettringite controller.

[0118] Furthermore, it was found that visually, concrete mixtures comprising ettringite formation controllers of the invention, with and without accelerator, are initially less viscous than comparative concrete mixtures without ettringite formation controllers, indicating a higher degree of pumpability and pulverization.

[0119] The accelerators were added to the concrete mixes as prepared above (“accelerated concrete mixes”) according to the following tables. Accelerated Concrete Mix C1-A2 C4-A1 ** C4-A2 ** C1-A3 C1A4 C4-A3 ** C4-A4 ** Concrete Mix Components C1 C1 C4 C4 C1 C1 C4 C4 Additional Components [% by weight]* Accelerator (SA 160) 6 8 6 8 — — — — Accelerator (SA 167) — — — — 5 7 5 7 Accelerated Concrete Mix C5A1 C7A1 C8A1 ** C8-A2 ** C5-A2 C7A2 C7A3 C8-A3 ** C8-A4 ** Concrete Mix Components C5 C7 C8 C8 C5 C7 C7 C8 C8 Additional Components [% by weight] * Accelerator (SA 160) 6 8 6 8 — — — — — Accelerator (SA 167) — — — — 5 5 7 5 7 * % by weight of aqueous solution relative to the weight of cement (bwoc) ** comparative example

[0120] The compressive strength of prisms prepared comprising accelerated concrete mixtures was measured after 4, 6 and 24 hours according to DIN EN 206-1 / DIN 1045-2. When using a Petition 870230082677, dated 09 / 18 / 2023, pp. 43 / 62 37 / 40 ZWICK 1446 machine, each prism was broken into two equal parts. Thus, two values ​​could be obtained for each prism.

[0121] The results are shown in Figs. 2a, 2b, 3a and 3b. It is evident that the concrete mixtures comprising the ettringite formation controller of the invention show significantly higher initial strength than the corresponding comparative concrete mixtures, which is particularly relevant for the earlier re-entry time in mines and tunnels and under difficult working conditions, such as unstable soil where rapid advance rates are required, or if thick layers need to be sprayed above. C.2) - Mortar Tests

[0122] Mortar mixtures from M1 to M12 with compositions according to the following tables were prepared. Mortar Mixture Component M1 M2 M3 * M4 * M5 M6 * Cement [g] (2:1 (w / w) Eiberg CEMI 52.5N:Fluasit) 836 836 836 836 — — Cement [g] (Mergelstetten CEMI 52.5R) — — — — 836 836 Standard Sand [g] (DIN EN196-1) 135 0 135 0 135 0 135 0 135 0 135 0 Plasticizer [% by weight]** (MG SKY 594) — — 0.4 0.4 — 0.3 Plasticizer [% by weight]** (Melflux 6680 L) 0.02 5 0.02 5 — — 0.04 — Accelerator [% by weight]*** (SA 160) — 8 — 8 — — Accelerator [% by weight]*** (SA 167) 7 — 7 — 7 7 Hydration control additive [% by weight]*** (MasterRoc HCA 10) — — 0.2 0.2 — — Ettringite formation controller [% by weight]** (BMF) 1.05 1.05 — — 1.05 — Water [g] (total quantity) 376.2 376.2 376.2 376.2 376.2 376.2 * Comparative example * * % by weight of the sum of solids of active components in relation to the weight of cement (bwoc) * ** % by weight of aqueous solution in relation to the weight of cement (bwoc) Component Mortar Mix M7 M8 * M9 * M10 M11 * M12 * Cement [g] (2:1 (w / w) Eiberg CEMI 52.5N:Fluasit) 836 836 836 — — — Cement [g] (Mergelstetten CEMI 52.5R) — — — 836 836 836 Normal sand [g] (DIN EN196-1) 1350 1350 1350 1350 1350 1350 Petition 870230082677, dated 09 / 18 / 2023, pp. 44 / 62 38 / 40 Plasticizer [% by weight]** (Melflux 6680 L) 0.02 5 0.02 5 0.02 5 0.04 0.04 0.04 Accelerator [% by weight]*** (SA 167) 7 — — 7 — — Accelerator [% by weight]*** (sodium aluminate) — 7 — — 7 — Accelerator [% by weight]*** (sodium silicate) — — 7 — — 7 Ettringite formation controller [% by weight]** (BMF) 1.05 1.05 1.05 1.05 1.05 1.05 Water [g] (total quantity) 372.6 372.6 372.6 372.6 372.6 372.6 * comparative example * * % by weight of the sum of solids of active components in relation to the weight of cement (bwoc) *** % by weight of aqueous solution in relation to the weight of cement (bwoc)

[0123] Mortar mixtures from M1 to M6 were obtained in a similar manner to the concrete mixtures described above, however, the difference in composition is that these mortar mixtures do not comprise aggregates in the range of 2 to 5 mm, so as to allow the measurement of the penetration resistance force using an electronic pulverized concrete penetrometer (Mecmesin AFG 500N) equipped with a 1.6 mm needle. Mixing and measuring procedure:

[0124] All components, except the accelerator, were mixed for 3.5 minutes, with the same initial consistency, and prepared in equally large buckets. Subsequently, the accelerators were added, and the mixtures were further mixed for 40 seconds. The resulting accelerated mortar mixtures were then compacted in the buckets to create a smooth, flat surface. The resistance force to penetration of a needle (1.6 mm diameter) into the mortar mixtures of the smoothed upper surface was measured over a period of 6 minutes to 6 hours (10 measurements for each time point to calculate an average), starting from the addition of the accelerators using the penetrometer mentioned above (Mecmesin AFG 500N). The results of the penetration resistance force measurements are directly correlated with the strength of the mortar mixtures and can be used as a Petition 870230082677, dated 09 / 18 / 2023, pp. 45 / 62 39 / 40 prediction for the corresponding large-scale concrete tests. The measurement results are shown in Figs. 4a, 4b, 5a and 5b.

[0125] Fig. 4a shows the results for mortar mixtures M1 to M4 comprising Eiberg CEMI 52.5N: Fluasit cement in a 2:1 (w / w) ratio. Comparison of M1 with M3 shows that in the presence of alkali-free accelerator SA 167, the mortar mixtures comprising the ettringite formation controller of the invention show significantly higher initial strength (6 minutes to 6 hours) than the mortar mixtures comprising reference hydration control additive HCA 10. Comparison of M2 with M4 shows that this effect is also observed in the presence of alkali-free accelerator SA 160.

[0126] Fig. 4b shows the results for mortar mixtures M5 and M6 comprising Mergelstetten CEMI 52.5R cement. Again, it is evident that in the presence of the alkali-free accelerator SA 167, the mortar mixture comprising the ettringite formation controller of the invention shows significantly higher initial strength (6 minutes to 6 hours) than the mortar mixture not comprising any ettringite formation controller.

[0127] Fig. 5a shows the results for mortar mixtures M7 to M9 comprising Eiberg CEMI 52.5N:Fluasit cement in 2:1 (w / w) and ettringite formation controller BMF. It is evident that in the presence of the alkali-free accelerator SA 167, the mortar mixture exhibits significantly higher initial strength (6 minutes to 6 hours) than in the presence of accelerators containing sodium aluminate and sodium silicate alkalis, respectively.

[0128] Fig. 5b shows the results for M10 to M12 mortar mixtures comprising Mergelstetten CEMI 52.5R cement and ettringite formation controller BMF. Again, it is evident that in the presence of alkali-free accelerator SA 167, the mortar mixture shows significantly higher initial strength (6 minutes to 6 hours). Petition 870230082677, dated 09 / 18 / 2023, pp. 46 / 62 40 / 40 greater than in the presence of accelerators containing alkaline sodium aluminate and sodium silicate, respectively. Petition 870230082677, dated 09 / 18 / 2023, pp. 47 / 62

Claims

1 / 4 CLAIMS 1. Shotcrete composition, characterized in that it comprises a) a cement binder; b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; and c) an alkali-free aluminum-based shotcrete accelerator selected from aluminum salts, aluminum complexes, aluminum hydroxides and mixtures thereof.

2. Composition according to claim 1, characterized in that the glyoxylic acid condensate is an amine-glyoxylic acid condensate, preferably a melamine-glyoxylic acid condensate, a urea-glyoxylic acid condensate, a melamine-urea-glyoxylic acid condensate and / or a polyacrylamide-glyoxylic acid condensate.

3. Composition according to claim 1 or 2, characterized in that the glyoxylic acid adduct is a glyoxylic acid bisulfite adduct or a salt or a mixed salt thereof, wherein the bisulfite adduct preferably has the general formula (I) OH M1OOC—CH XSO3M1 (|) wherein M1 is independently selected from H or an equivalent of Kr cation, wherein K is selected from an alkali metal, alkaline earth metal, zinc, copper, iron, aluminum, ammonium or phosphonium cation, or mixtures thereof, er is 1 / v, wherein v is the valence of the cation.

4. Composition, according to any of the preceding claims, characterized in that the ettringite formation controller further comprises (ii) a carbonate source, which is preferably selected from inorganic carbonates with an aqueous solubility of 0.1 g L-1 or more, organic carbonates and mixtures thereof.

5. Composition according to claim 4, characterized in that the inorganic carbonate is selected from sodium carbonate, lithium carbonate and magnesium carbonate; and the organic carbonate is selected from ethylene carbonate and propylene carbonate.

6. Composition, according to any of the preceding claims, characterized in that the ettringite formation controller further comprises (iii) a component selected from - polycarboxylic acids or salts thereof having a milliequivalent number of carboxyl groups of 5.00 meq / g or higher, preferably 5.00 to 15.00 meq / g, assuming that all carboxyl groups are in the unneutralized form; and - α-hydroxycarboxylic acids or salts thereof.

7. Composition according to claim 6, characterized in that the polycarboxylic acid is selected from phosphonoalkyl carboxylic acids, aminocarboxylic acids and polymeric carboxylic acids.

8. Composition, according to any of the preceding claims, characterized in that the cement binder is selected from Portland cement, calcium aluminate cement and / or sulfoaluminate cement.

9. Composition, according to any of the preceding claims, characterized in that the composition further comprises a latent hydraulic binder or a pozzolanic binder, or mixtures thereof. Petition 870240086870, dated 09 / 10 / 2024, page 13 / 19 3 / 4 10. A composition, according to any of the preceding claims, characterized in that it further comprises a dispersant.

11. Composition according to claim 10, characterized in that the dispersant is selected from the group of - comb polymers with a carbon-containing main chain to which pendant cement anchoring groups and polyether side chains are attached, - nonionic comb polymers with a carbon-containing main chain to which pendant hydrolyzable groups and polyether side chains are attached, the hydrolyzable groups releasing cement anchoring groups upon hydrolysis, - sulfonated melamine-formaldehyde condensates, - lignosulfonates, - sulfonated ketone-formaldehyde condensates, - sulfonated naphthalene-formaldehyde condensates, - phosphonate-containing dispersants, - phosphate-containing dispersants and - mixtures thereof.

12. Process, characterized in that it comprises: - providing a cement composition comprising a) a cement binder and b) an ettringite formation controller comprising (i) a glyoxylic acid condensate and / or a glyoxylic acid adduct; - mixing an alkali-free aluminum-based shotcrete accelerator selected from aluminum salts, aluminum complexes, aluminum hydroxides and mixtures thereof into the cement composition to obtain a shotcrete composition; and Petition 870240086870, dated 09 / 10 / 2024, page 14 / 19 4 / 4 - applying the shotcrete composition to a surface to obtain a shotcrete structure and allowing the shotcrete structure to harden. Petition 870240086870, dated 09 / 10 / 2024, page 15 / 19

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