Accelerators for mineral binder compositions

Abstract

The present invention relates to an accelerator for a mineral binder composition, the accelerator comprising: a) an aqueous suspension of calcium hydroxide; and b) at least one material I selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, especially lithium carbonate, alkali metal bicarbonates, especially sodium bicarbonate, organic acids, or mixtures thereof. The present invention also relates to a method for accelerating a mineral binder composition with such an accelerator.

Description

[Technical Field]

[0001] The present invention relates to an accelerator for a mineral binder composition. The present invention also relates to a method for accelerating a mineral binder composition. [Background technology]

[0002] Cement is a mineral binder used primarily in concrete and mortar. When cement is mixed with water, it sets and hardens in a chemical process called cement hydration. The cement hydrate thereby formed acts as a binder for the aggregates in concrete and mortar, usually sand, gravel, and stone, to form a solid material. There are many applications for mortar and concrete where rapid setting and hardening, and therefore rapid strength development, are very important.

[0003] There are various ways to accelerate the setting and / or hardening of cement. A very common approach is to add accelerators, such as calcium chloride, calcium nitrite, or sodium nitrite, and / or amines, such as alkanolamines. Some accelerators are known to specifically affect the setting of mineral binders, while others are known to affect hardening, leading to increased early and / or late strength of the mineral binder composition.

[0004] Many accelerators for mineral binder compositions are known in the prior art. For example, EP 3 536 677 (Yara International) discloses the use of nitrates as setting and hardening accelerators, and U.S. Pat. No. 4 337 094 (Euclid Chem) discloses the use of nitrates in combination with alkanolamines. The use of calcium formate and thiocyanate as accelerators for Portland cement is known, for example, from DE 2 611 419 (Degussa). A combination of thiocyanate and alkanolamine is disclosed in U.S. Pat. No. 4 373 956 (Martin Marietta). WO 2010 / 026155 (Construction Research & Technology) discloses calcium silicate hydrate as an accelerator for mineral binder compositions.

[0005] A particularly useful accelerator for mineral binder compositions is calcium hydroxide. The use of an aqueous suspension of calcium hydroxide as an accelerator for mineral binder compositions is known from WO 2019 / 180191 (Sika Technology).

[0006] Known accelerators for mineral binder compositions are not always capable of simultaneously increasing early and later strength. In addition, it would be desirable to have an accelerator composition that increases early and later strength for both mineral binders that consist essentially of Portland cement, as well as mineral binders that are based on blended cements, such as limestone cement, slag cement, or mixtures of Portland cement with other supplemental cementitious materials.

[0007] Thus, there is a continuing need for improved accelerator compositions and methods for accelerating mineral binder compositions, particularly blended cement-based mineral binder compositions. Summary of the Invention [Means for solving the problem]

[0008] It is an object of the present invention to provide an accelerator for a mineral binder composition. In particular, the accelerator of the present invention should improve the early-age strength of the mineral binder composition when compared to the same mineral binder composition without the accelerator. Early-age strength refers to the strength, particularly compressive strength, measured within 1 to 24 hours after adding water to the mineral binder composition. In particular, the accelerator of the present invention should improve the early-age strength of blended cements.

[0009] It is also an object of the present invention to provide a method for promoting mineral binder compositions, especially mineral binder compositions based on blended cements.

[0010] Surprisingly, these objects have been solved by the accelerators and methods according to the independent claims.

[0011] Preferred embodiments of the invention are the subject of the dependent claims. DETAILED DESCRIPTION OF THE INVENTION

[0012] Methods of carrying out the present invention In a first aspect, the present invention provides an accelerator for a mineral binder composition, the accelerator comprising: a) an aqueous suspension of calcium hydroxide; b) at least one material I selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, in particular lithium carbonate, alkali metal bicarbonates, in particular sodium bicarbonate, organic acids, or mixtures thereof; The present invention relates to an accelerator comprising:

[0013] Acceleration of the mineral binder composition can be measured as an increase in strength, particularly compressive strength, of the mineral binder composition when compared to the same mineral binder composition without the addition of the accelerator, measured at a predetermined time point after the onset of hardening.

[0014] Acceleration can also be measured as a decrease in setting time.

[0015] The mineral binder composition may be a mineral binder such as cement or a binder comprising cement. The mineral binder composition may be a formulated product such as dry mortar, wet mortar, or concrete.

[0016] The mineral binder composition is therefore characterized in that it comprises at least one mineral binder. The mineral binder in the context of the present invention is in particular cement. The mineral binder composition may also comprise additional minerals commonly used in the concrete or mortar industry. In particular, the mineral binder composition may comprise fillers, aggregates, and admixtures.

[0017] An "aqueous suspension" in the context of the present invention is a suspension of particles in a continuous liquid phase that comprises or consists essentially of water. Specifically, the continuous liquid phase does not contain, apart from water, other solvents such as, for example, alcohols, glycols, or ketones. The liquid phase may also contain a surfactant.

[0018] It is highly preferred that calcium hydroxide is present in the aqueous suspension in the form of suspended nanoparticles. "Nanoparticles" are particles with a particle size in the nanometer range. These ultrafine particles are known for their very high specific surface area and consequent specific properties. "Nanoparticles" in this specification refer to particles with a particle size of less than 1 μm. The particle size of nanoparticles in suspension can be measured by dynamic light scattering with photon cross-correlation spectroscopy in accordance with the ISO 22412:2017 standard.

[0019] Within the context of the present invention, the average particle size corresponds in particular to the D50 value (50% of the particles are smaller than the specified value and 50% are correspondingly larger than the specified value). Thus, the value "D10" indicates that 10% of the particles have a particle size smaller than this value. The value "D90" indicates that 90% of the particles have a particle size smaller than this value.

[0020] According to an embodiment, the accelerator of the invention is characterized in that the aqueous suspension comprises calcium hydroxide in the form of nanoparticles, in particular calcium hydroxide having a particle size D90 of less than 800 nm, preferably less than 600 nm, more preferably less than 400 nm, in particular less than 200 nm, measured by dynamic light scattering with photon cross-correlation according to the ISO 22412:2017 standard.

[0021] For the purposes of this invention, the particle size of calcium hydroxide particles has been determined using a Nanophox instrument from Sympatec, Germany, where the particle size is determined by dynamic light scattering with photon cross-correlation.

[0022] Suspensions containing calcium hydroxide particles having the particle size described above are particularly storage stable and highly effective in promoting mineral binder compositions, especially cementitious compositions.

[0023] According to an embodiment, at least 50% by weight, preferably at least 66% by weight, more preferably at least 90% by weight, and especially substantially all, of the calcium hydroxide present in the aqueous suspension is in the form of suspended nanoparticles.

[0024] According to an embodiment, the aqueous suspension further comprises at least one organic compound to stabilize the suspension: at least one organic polymer containing carboxylate, sulfate, sulfonate, phosphate, and / or phosphonate groups. The organic polymer preferably acts as a plasticizer for the mineral binder composition, especially for cementitious compositions. Examples of suitable organic polymers include lignosulfonates, sulfonated naphthalene-formaldehyde condensates, sulfonated melamine-formaldehyde condensates, sulfonated vinyl copolymers, poly(meth)acrylic acid, copolymers of (meth)acrylic acid with (meth)acrylic acid esters or hydroxyalkyl (meth)acrylates, polyalkylene glycols containing phosphonate groups, polyalkylene glycols containing phosphate groups, comb polymers with anionic groups and polyether side chains, or salts thereof, or mixtures of these polymers.

[0025] The organic polymer is more particularly a comb polymer comprising a polymer backbone with polyalkylene oxide side chains and anionic groups attached to the backbone, where the side chains are attached to the polycarboxylate backbone, particularly via ester, ether, imide and / or amide groups. The comb polymer preferably comprises polyalkylene oxide units, more particularly polyethylene oxide units.

[0026] The aqueous suspension of calcium hydroxide is preferably obtained as described in WO 2019 / 180191 (Sika Technology).

[0027] The at least one material I is selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, in particular lithium carbonate, alkali metal bicarbonates, especially sodium bicarbonate, organic acids, or mixtures thereof.

[0028] Alkanolamine is an amine having at least one pendant hydroxyalkyl group.Preferred alkanolamines are monoethanolamine, diethanolamine, diisopropanolamine, triethanolamine (TEA), isopropanolamine, triisopropanolamine (TIPA), N-methyldiethanolamine (MDEA), N-methyldiisopropanolamine (MDIPA), ethyldiisopropanolamine (EDIPA), diethanolisopropanolamine (DEIPA), tetrahydroxyethylethylenediamine (THEED), and tetrahydroxyisopropylethylenediamine (THIPD).Particularly preferred alkanolamines are triethanolamine (TEA), triisopropanolamine (TIPA), and N-methyldiethanolamine (MDEA).

[0029] Suitable organic acids are especially formic acid, acetic acid, propionic acid, caprylic acid, lauric acid, linoleic acid, myristic acid, oleic acid, behenic acid, benzoic acid, oxalic acid, and succinic acid.

[0030] Particularly suitable materials I are mixtures of sodium nitrate and alkanolamines, especially mixtures of sodium nitrate with triethanolamine (TEA), triisopropanolamine (TIPA) or N-methyldiethanolamine (MDEA).

[0031] Another particularly suitable material I is a mixture of sodium nitrate and sodium thiocyanate.

[0032] Another particularly suitable material I is a mixture of sodium nitrate, calcium nitrate, and sodium thiocyanate.

[0033] Further particularly suitable materials I are mixtures of sodium nitrate, calcium nitrate, sodium thiocyanate with alkanolamines, especially triethanolamine (TEA), triisopropanolamine (TIPA), or N-methyldiethanolamine (MDEA).

[0034] Further particularly suitable materials I are mixtures of sodium nitrate, calcium nitrate, sodium thiocyanate, formic acid with alkanolamines, especially triethanolamine (TEA), triisopropanolamine (TIPA), or N-methyldiethanolamine (MDEA).

[0035] According to an embodiment, the enhancer of the present invention is in the form of a single component that is an aqueous suspension.

[0036] The term "single-component" means that the aqueous suspension of calcium hydroxide also contains at least one material I. Preferably, in a single-component accelerator, at least one material I is dissolved in the aqueous suspension of calcium hydroxide. Thus, the accelerator of the present invention is in the form of a single component, comprising the aqueous suspension of calcium hydroxide and at least one material I in one container. Such a single-component accelerator is particularly easy to handle and dispense.

[0037] According to an embodiment, the accelerator of the present invention is in the form of two components, in which the aqueous suspension of calcium hydroxide and the at least one material I are stored in spatially separated containers and are only mixed during or immediately before use.

[0038] The term "two-component" means that the aqueous suspension of calcium hydroxide and the at least one component I are stored in spatially separated containers and are mixed only during or immediately before use. In such cases, the at least one component I may be in the form of a powder or an aqueous preparation, preferably in the form of an aqueous solution. Such two-component accelerators have the advantage that the dosage ratio of the individual components can be easily adjusted.

[0039] According to an embodiment, the accelerator of the invention is characterized in that calcium hydroxide is present in an amount of 5 to 65% by weight, preferably 8 to 15% by weight, and at least one material I is present in an amount of 20 to 66% by weight, in each case based on the total weight of the accelerator. It will be clear to those skilled in the art that water and further additives, in particular at least one organic polymer as described above, together make up 100% by weight of the accelerator.

[0040] In the case where the at least one material I comprises a mixture of two or more of alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, especially lithium carbonate, alkali metal bicarbonates, especially sodium bicarbonate, organic acids, the dosage ranges refer to the sum of all these chemicals in such mixture.

[0041] The accelerator of the present invention may contain further additives. For example, the accelerator of the present invention may contain a setting retarder such as a sugar, a sugar acid, or a hydroxycarboxylic acid, especially citric acid, lactic acid, or tartaric acid. For example, the accelerator of the present invention may contain a thickener such as a cellulose ether, starch, a modified starch, a layered silicate, or an alkaline thickening polymer. For example, the accelerator of the present invention may contain a defoamer, a biocide, a corrosion inhibitor, or a pigment.

[0042] The accelerators of the present invention may also comprise glycols, surfactants, in particular non-ionic surfactants such as alkyl polyglucosides, gemini surfactants, such as sodium lauryl ether sulfate, calcium stearate, silicones, alkoxylated phosphonates or phosphates, 1,3-propanediol, carboxylic acids, sulfonated amino alcohols, boric acid, borates, borax, salts of phosphonates or phosphoric acids, gluconates, iron sulfate, tin sulfate, antimony salts, glycerol, water-absorbing substances, in particular in the form of superabsorbent polymers or layered silicates such as vermiculite, bentonite, sugars, sugar acids, sugar alcohols, tall oil, polysaccharides, such as starch, jute gum, xanthan gum, gellan gum, guar gum, welan gum or carrageenan, cellulose ethers, polyvinyl alcohol, proteins, in particular gelatin and / or casein, and mixtures thereof.

[0043] In another aspect, the present invention provides a method of promoting a mineral binder composition, said method comprising: 1) providing a mineral binder composition; 2) providing an accelerator comprising: a) and b) a) an aqueous suspension of calcium hydroxide; b) at least one material I selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, in particular lithium carbonate, alkali metal bicarbonates, in particular sodium bicarbonate, organic acids, or mixtures thereof, and 3) mixing said mineral binder composition with said at least one material I; The present invention relates to a method for providing the same.

[0044] The above-described embodiment also applies to this aspect.

[0045] In particular, a particularly suitable material I for use in the method of the present invention is a mixture of sodium nitrate and an alkanolamine, particularly a mixture of sodium nitrate and triethanolamine (TEA), triisopropanolamine (TIPA), or N-methyldiethanolamine (MDEA). Another particularly suitable material I for use in the method of the present invention is a mixture of sodium nitrate and sodium thiocyanate. Another particularly suitable material I for use in the method of the present invention is a mixture of sodium nitrate, calcium nitrate, and sodium thiocyanate. Another particularly suitable material I for use in the method of the present invention is a mixture of sodium nitrate, calcium nitrate, sodium thiocyanate, and an alkanolamine, particularly triethanolamine (TEA), triisopropanolamine (TIPA), or N-methyldiethanolamine (MDEA). Another material I that is particularly suitable for use in the method of the invention is a mixture of sodium nitrate, calcium nitrate, sodium thiocyanate, formic acid and an alkanolamine, in particular triethanolamine (TEA), triisopropanolamine (TIPA) or N-methyldiethanolamine (MDEA).

[0046] The mineral binder composition may be a mineral binder such as cement or a binder comprising cement. The mineral binder composition may be a formulated product such as dry mortar, wet mortar, or concrete.

[0047] The mineral binder composition is therefore characterized in that it comprises at least one mineral binder. The mineral binder within the context of the present invention is in particular cement.

[0048] According to an embodiment, in the method of the present invention, the mineral binder composition comprises or consists of ordinary Portland cement, blended cement, aluminate cement, and / or calcium sulfoaluminate cement.

[0049] Ordinary Portland cement is particularly CEMI according to the EN197-1 standard. The term "blended cement" refers to a mixture of cement, particularly Portland cement, with auxiliary cementitious materials such as limestone, pozzolana, and latent hydraulic materials. The blended cement is particularly CEMII, CEMII, CEMIV, or CEMV according to the EN197-1 standard, or CEMII or CEMVI according to the EN197-5 standard. Blended cements according to other standards, such as ASTM C595, are also suitable. The blended cement is particularly a mixture of ordinary Portland cement with at least one of limestone, slag, fly ash, silica fume, clay (calcined or raw), tuff, marl, pumice, volcanic ash, zeolitic tuff, diatomaceous earth, kiln dust, microsilica, pyrogenic silica, precipitated silica, calcined oil shale, and organic matter calcination residues. Gypsum is usually present as part of ordinary Portland cement or may be added as an additional component.

[0050] According to an embodiment, in the method of the present invention, the mineral binder comprises a blend of Portland cement and limestone.

[0051] Particularly suitable blended cements comprise or consist of ordinary Portland cement, limestone, clay, preferably calcined clay, and optionally gypsum.

[0052] According to an embodiment, in the method of the present invention, the accelerator is introduced in an amount to provide calcium hydroxide in an amount of 0.01 to 1.0 wt. %, preferably 0.1 to 0.2 wt. %, based on the dry weight of the mineral binder.

[0053] According to an embodiment, in the method of the invention, the accelerator is introduced in an amount to provide at least one material I in an amount of at least 0.1% by weight, preferably at least 0.44% by weight, more preferably at least 0.7% by weight, relative to the dry weight of the mineral binder.

[0054] According to an embodiment, in the method of the invention, the accelerator is introduced in an amount to provide at least one material I in an amount of not more than 5% by weight, preferably not more than 2.66% by weight, relative to the dry weight of the mineral binder.

[0055] According to an embodiment, the accelerator is introduced in an amount to provide calcium hydroxide in an amount of 0.01 to 1.0% by weight, preferably 0.1 to 0.2% by weight, and at least one material I in an amount of 0.1% by weight or more, preferably 0.44% by weight or more, more preferably 0.7% by weight or more, and 5% by weight or less, preferably 2.66% by weight or less, based on the dry weight of the mineral binder.

[0056] When material I consists of or comprises MDEA, it is preferred that the total loading of MDEA relative to the mineral binder is 0.2% by weight or less, more preferably 0.16% by weight or less.

[0057] When material I consists of or comprises sodium thiocyanate, the total amount of sodium thiocyanate relative to the mineral binder is preferably 3.0% by weight or less, more preferably 1.5% by weight or less.

[0058] Dosages of calcium hydroxide and / or at least one material I below the lower limit defined above usually result in reduced and often insufficient acceleration, whereas dosages of calcium hydroxide and / or at least one material I above the upper limit defined above usually do not lead to a further increase in acceleration but may lead to increased costs or even reduced acceleration.

[0059] According to an embodiment, in the method of the present invention, the accelerator is added to the mineral binder compositions before or during their grinding.

[0060] In this case, the mineral binder composition is a dry mineral binder composition, which may advantageously be ordinary Portland cement, a blended cement or a component of a blended cement as defined above.

[0061] According to an embodiment, in the method of the present invention, the accelerator is added to the mineral binder composition together with the mixing water or immediately after the mixing water.

[0062] Further advantageous embodiments of the present invention will become apparent from the following examples. [Example]

[0063] Nanophox particle size The particle size of calcium hydroxide nanoparticles in aqueous suspension was determined by dynamic light scattering with photon cross-correlation. The instrument used for the measurements was a Nanophox from Sympatec GmbH, Germany. The aqueous suspension was analyzed without further dilution. Prior to the measurement, the sample was homogenized with an ultrasonic probe for 1 minute.

[0064] Chemicals used Unless otherwise stated, chemicals were purchased at high purity from Sigma Aldrich and used as received.

[0065] Preparation of an aqueous suspension of calcium hydroxide A first solution was prepared by dissolving 174.4 g of Ca(NO3)2·4H2O (0.739 mol) and 10 g of comb polymer (copolymer of acrylic acid and polyethylene glycol methacrylate; polyethylene glycol Mw: 5000 g / mol) in 82 g of water. A second solution was prepared by dissolving 59.1 g of NaOH (1.478 mol) in 220 g of water. The first solution was placed in a 1-liter round-bottom flask. While vigorously stirring with a propeller stirrer, the second solution was added via a dropping funnel over 5 minutes. The resulting suspension was stirred for an additional 60 minutes. The resulting suspension was purified by ultrafiltration using a polyethersulfone membrane with a size exclusion limit of 30 kDa. In this procedure, NaNO3 was removed and the suspension was concentrated. The suspension was then diluted with purified water to a content of 10 wt% Ca(OH)2 in the form of nanoparticles. The obtained suspension S1 had a content of 10% by weight of Ca(OH)2 in the form of nanoparticles. The particle size D50, measured as defined above, was 163 nm.

[0066] Mortar preparation and testing 750 g of cement (CEMI52.5R or CEMII A-LL, as shown in Tables 1-4 below), 738 g of sand (0-1 mm), 1107 g of sand (1-4 mm), and 1154 g of sand (4-8 mm) were dry mixed in a Hobart mixer for 1 minute at 25°C. Next, a superplasticizer (polycarboxylate ether; 1 wt.% based on cement) and water were added in amounts to achieve a water-to-cement weight ratio (w / c) of 0.39. The water from suspension S1 was taken into account in the w / c ratio calculation. Mixing then continued for 30 seconds. Mixing was stopped, the mixing bowl scraped, and the accelerator, type and amount shown in Table 1 below, was added. Mixing then continued for another minute.

[0067] The compressive strength of the obtained mortar mixtures was tested according to the EN12190 standard on a prism of 4x4x16 cm after the times shown in Tables 1 to 4 below.

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3]

[0071] [Table 4]

[0072] From the above examples it can be seen that the accelerator according to the present invention increased the early strength of the mineral binder composition.

Claims

1. 1. An accelerator for a mineral binder composition, said accelerator comprising: a) an aqueous suspension of calcium hydroxide; b) at least one material I selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, in particular lithium carbonate, alkali metal bicarbonates, in particular sodium bicarbonate, organic acids, or mixtures thereof; A promoter comprising:

2. 2. The accelerator of claim 1, wherein said at least one material I is a mixture of sodium nitrate, calcium nitrate, and sodium thiocyanate.

3. 2. The accelerator according to claim 1, wherein the at least one material I is a mixture of sodium nitrate, calcium nitrate, sodium thiocyanate and an alkanolamine, in particular triethanolamine (TEA), triisopropanolamine (TIPA), or N-methyldiethanolamine (MDEA).

4. 4. The accelerator according to claim 1, wherein the aqueous suspension comprises calcium hydroxide in the form of nanoparticles, in particular calcium hydroxide having a particle size D90 of less than 800 nm, preferably less than 600 nm, more preferably less than 400 nm, in particular less than 200 nm, measured by dynamic light scattering with photon cross-correlation according to the ISO 22412:2017 standard.

5. 5. The accelerator according to claim 1, wherein the accelerator is in the form of a single component comprising the aqueous suspension of calcium hydroxide and the at least one material I in one container.

6. 6. The accelerator according to claim 1, wherein the accelerator is in the form of two components, the aqueous suspension of calcium hydroxide and the at least one material I being stored in spatially separated containers and being mixed only during or immediately before use.

7. 7. Accelerator according to any one of claims 1 to 6, characterized in that calcium hydroxide is present in an amount of 5 to 65% by weight, preferably 8 to 15% by weight, and the at least one material I is present in an amount of 20 to 66% by weight, in each case relative to the total weight of the accelerator.

8. 1. A method of promoting a mineral binder composition, said method comprising: 1) providing a mineral binder composition; 2) providing an accelerator comprising: a) and b) a catalyst; a) an aqueous suspension of calcium hydroxide; b) at least one material I selected from alkanolamines, sodium thiocyanate, sodium nitrate, sodium nitrite, calcium nitrate, calcium silicate hydrate, sodium silicate, aluminum sulfate, sodium sulfate, sodium aluminate, alkali metal carbonates, in particular lithium carbonate, alkali metal bicarbonates, in particular sodium bicarbonate, organic acids, or mixtures thereof, and 3) mixing said mineral binder composition with said at least one material I; A method comprising:

9. 9. The method of claim 8, wherein the mineral binder composition comprises or consists of ordinary Portland cement, blended cement, aluminate cement, and / or calcium sulfoaluminate cement.

10. 10. The method of claim 9, wherein the mineral binder comprises a blend of Portland cement and limestone.

11. 11. A method according to any one of claims 8 to 10, characterized in that the accelerator is introduced in an amount to provide calcium hydroxide in an amount of 0.01 to 1.0 wt. %, preferably 0.1 to 0.2 wt. %, relative to the dry weight of the mineral binder.

12. 12. The method according to any one of claims 8 to 11, characterized in that the accelerator is introduced in an amount to provide the at least one material I in an amount of at least 0.1 wt.-%, preferably at least 0.44 wt.-%, more preferably at least 0.7 wt.-%, relative to the dry weight of the mineral binder.

13. 13. The method according to any one of claims 8 to 12, characterized in that the accelerator is introduced in an amount to provide the at least one material I in an amount of not more than 5% by weight, preferably not more than 2.66% by weight, relative to the dry weight of the mineral binder.

14. The method according to any one of claims 8 to 13, characterized in that the accelerator is added to the mineral binder composition before or during grinding.

15. A method according to any one of claims 8 to 13, characterized in that the accelerator is added to the mineral binder composition together with the mixing water or immediately after the mixing water.

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