Calcium silicate hydrate composition

Abstract

The present invention relates to a composition comprising calcium silicate hydrate, water and a water-soluble polymeric dispersant, wherein the ratio of calcium silicate hydrate to the water-soluble polymeric dispersant is 15:1 to 1:3 and wherein the composition comprises 0.3 to 25 wt.-% of α-dicalcium silicate hydrate based on the dry weight of the composition. Furthermore, processes for producing the composition according to the invention and the use of the composition as curing accelerator for hydraulic binders are disclosed. Further the use of α-dicalcium silicate hydrate in a calcium silicate hydrate suspension comprising water and a water-soluble polymeric dispersant is disclosed, to improve storage stability by reducing the viscosity increase.

Description

[0001] BASF SE 240796W001

[0002] 1

[0003] Calcium silicate hydrate composition

[0004] The present invention relates to a composition comprising calcium silicate hydrate, water and a water-soluble polymeric dispersant, wherein the composition comprises 0.3 to 25 wt.-% of a -dicalcium silicate hydrate (a -C2SH) based on the dry weight of the composition. Furthermore, processes for producing the composition according to the invention and the use of the composition as curing accelerator for hydraulic binders are disclosed.

[0005] In cement hydration, the various cement clinker phases react with water to form mainly the hydrate phases calcium silicate hydrate, ettringite, calcium-aluminate-ferrite phases, monosulfate (kuzelite) and portlandite.

[0006] Accelerating cement hydration by addition of calcium silicate hydrate nuclei to cement is known from WO 2010 / 026155. The strength development of a cement can thus be accelerated by the addition of such calcium silicate hydrate nuclei. The calcium silicate hydrate nuclei are obtainable by reaction of a water-soluble calcium component with a water-soluble silicon component in aqueous solution or by reaction of a calcium compound with silicon dioxide, in each case in the presence of a water-soluble comb polymer which is suitable as plasticizer for hydraulic binders. The compositions obtained here have an excellent accelerating effect but also a relatively high viscosity which can make use difficult, for example when the composition has to be pumped or sprayed.

[0007] A setting and curing accelerator for siliceous, hydraulic binders which is obtained, in particular, from the hydration of portland cements, comminuted portland clinkers or formulated portland cements or mixtures of the abovementioned starting materials by hydration at < 90° C and subsequent milling is known from WO 95 / 04007.

[0008] WO 2013 / 017391 describes a process for producing a quick-setting hydraulic binder by milling a cement clinker with from 0.1 to 5% by weight of a material comprising more than 15% by weight of calcium silicate hydrate. Water reducers, which are polyoxyalkylene polycarboxylates, can also be comilled here. The commercially available, crystalline Circolit® is used as calcium silicate hydrate-comprising material.

[0009] WO 2017 / 032719 describes a process for producing a composition which is suitable as accelerator for the curing of cement. The process comprises contacting of a hydraulic or latent hydraulic binder with a dispersant which is suitable for dispersing inorganic particles in water.

[0010] The accelerators based on calcium silicate hydrate which are known from the prior art either have an unsatisfactory accelerating effect or are associated with use disadvantages (excessively high viscosity, corrosivity), so that the economically feasible use possibilities are limited.BASF SE 240796W001

[0011] 2

[0012] WO 2018 / 154012 describes a curing accelerator composition for hydraulic binders which comprises a mineral constituent and a polymeric water-soluble dispersant. The mineral constituent comprises a semi-ordered calcium silicate hydrate having an apparent crystallite size of 15 nm or less and less than 35% by weight of crystalline phases other than the semi-ordered calcium silicate hydrate. The composition provides an excellent accelerating effect in hydraulic binders. A disadvantage of this curing accelerator is a viscosity increase of the suspension over time, which gets further accelerated with higher temperatures. After a few weeks storage at room temperature, the suspension reaches a viscosity > 2000 mPas and loses its workability and transforms into a gel.

[0013] WO 2019 / 058313 describes an accelerating admixture for hydraulic compositions based on C-S-H seeds, which is obtainable by hydration in aqueous suspension of a hydraulic binder based on Portland cement or other hydraulic binders with a mainly silicate base, with a water / binder ratio (W / B) ranging from W / B = 1 to W / B = 6, at a temperature ranging from 10° C to 90° C, for times ranging from 2 hours to 300 hours, in the presence of carboxylic acids, the calcium salts thereof, polyethanolamines, or mixtures thereof. A disadvantage of this curing accelerator is the high amount of aluminate phases which results in higher incompatibility with respect to rheology in the application when the curing agent is used in cementitious composition. Furthermore the curing agent according to WO 2019 / 058313 shows increased viscosity of the suspension resulting in problems during sample handling and application for example when the composition has to be pumped or sprayed.

[0014] WO 2022 / 073961 relates to a process for producing calcium silicate hydrate under hydrothermal conditions with improved storage stability, wherein an organic compound is added in at least one of the process steps and wherein the organic compound has a molecular weight of 100 to 600 g / mol and from 0,02 to 0,035 functional groups per gram of the organic compound, wherein the functional groups being selected from -OH, -COOH, -COOMa, -SO3H or -SO3Ma, or -C(=O)H, wherein M is hydrogen, a mono-, di- or trivalent metal cation, ammonium ion or an organic amine radical and a is 1 / 3, 1 / 2 or 1.

[0015] It is therefore an object of the present invention to provide a alternative calcium silicate hydrate composition which, in particular, has a satisfactory accelerating effect on the curing of hydraulic and latent hydraulic binders and a improved long-term storage stability as a suspension. In particular, the composition should be easy-to-handle, in particular have a viscosity which allows easy pumping and spraying of the composition even after a prolonged storage time at room temperature and elevated temperature (e.g. 40 ° C), and be suitable as curing accelerator for hydraulically or latently hydraulically setting binders and thus improve the early strength of the hydraulically or latently hydraulically setting binders, in particular portland cement. Furthermore, the composition should be able to be produced economically advantageously using cheap and readily available raw materials.

[0016] The term early strength in connection with hydraulically setting binders is for the present purposes the compressive strength 6 hours after mixing of the hydraulically setting binderBASF SE 240796W001

[0017] 3

[0018] with water. In the case of latently hydraulically setting binders, the early strength is the compressive strength 7 days after mixing the hydraulically setting binder with water.

[0019] The expression “comprising” or “comprises” used here also encompasses the expressions “consisting essentially of” and “consisting of” without being synonymous with these expressions.

[0020] It has surprisingly been found that this object is achieved by a calcium silicate hydrate composition comprising water and a water-soluble polymeric dispersant, wherein the ratio of calcium silicate hydrate to the water-soluble polymeric dispersant is 15:1 to 1:3, wherein the composition comprises 0.3 to 25 wt.-% of a -dicalcium silicate hydrate, XRD evaluation with the Rietveld method, based on the dry weight of the composition.

[0021] It has been found that the composition has an excellent accelerating effect on the curing of hydraulic or latent hydraulic binders. Furthermore, the compositions of the invention remains pumpable even at high solids contents over a long period of time.

[0022] It is preferred that the composition according to the invention comprises 0.8 to 15 wt.-%, in particular from 1.0 - 12 wt.-%, particularly preferably from 1.2 - 8 wt.-% of a -dicalcium silicate hydrate based on the dry weight of the composition.

[0023] In a further preferred embodiment the calcium silicate hydrate composition according to the invention consists of particles with a d(50) particle size of < 800 nm, preferably < 400 nm, more preferably < 300 nm, particularly preferably < 200 nm determined by static light scattering according to ISO 13320:2020.

[0024] It is also preferred that the calcium silicate hydrate composition according to the invention comprises 20 - 93 wt.-%, preferably 40 - 88 wt.-%, in particular from 65 - 85 wt.-% of calcium silicate hydrate based on the dry weight of the composition.

[0025] In a further preferred embodiment the calcium silicate hydrate composition comprises between 24 to 99 wt.-%, preferably between 30 to 80 wt.-%, particularly preferably between 40 to 60 wt.-% of water.

[0026] It is also preferred that the ratio of calcium silicate hydrate to the water-soluble polymeric dispersant is 12:1 to 1:2, preferably 10:1 to 1:1,5 particularly preferably 5:1 to 1:1.

[0027] In a further preferred embodiment the calcium silicate hydrate composition of the invention is essentially free of cement, cement clinker and / or ettringite. Here, “essentially free” means less than 10 wt.-% or less than 8 wt.-%, preferably less than 5 wt.-% or 3 wt.-% and in particular 1 wt.-% or 0 wt.-%, in each case based on the dry weight of the composition.BASF SE 240796W001

[0028] 4

[0029] The present invention provides several alternatives to produce the calcium silicate hydrate composition according to the invention comprising a -dicalcium silicate hydrate.

[0030] The preparation of a -dicalcium silicate hydrate (a-C2SH) is known to the person skilled in the art.

[0031] From H. Ishida, S. Yamazaki, K. Sasaki, Y. Okada, T. Mitsuda, "Dicalcium Silicate Hydrate: Preparation, Decomposed Phase, and Its Hydration," J. Am. Ceram. Soc. 76, pp. 1707-1712, 1993, it is known that a -dicalcium silicate hydrate ( a -C2SH) is formed at 200 ° C through a two-hour hydrothermal treatment of quick lime and silica.

[0032] Further the preparation of a -dicalcium silicate hydrate is known from US 4,330,519 reference example 5, wherein quick lime is used as a lime material and minus 350 mesh siliceous sand powder (Tyler scale) as a siliceous material. The materials are dispersed in water in a calcium oxide to silicium dioxide mole ratio of 2.0: 1 to prepare a slurry having a water to solids ratio of 4:1 by weight. The slurry is placed in an autoclave and subjected to hydrothermal reaction at a temperature of 191 ° C and a saturated vapor pressure of 12 kg / cm2with heating for 5 hours to obtain a slurry of a -dicalcium silicate hydrate. The x-ray diffraction of the crystals shows diffraction peaks (29 ) at 16.6° , 27.3° and 37.2° peculiar to a -dicalcium silicate hydrate crystals.

[0033] The process product as disclosed in US 4,330,519 is suitable to be used in the present invention.

[0034] WO 2007 / 017142 discloses a process to produce a -dicalcium silicate hydrate as an intermediate for the production of a Belite-binder.

[0035] The process comprising the steps:

[0036] a) Seeding of a starting material containing calcium oxide and silicon dioxide in a molar Ca:Si ratio between 2.5:1 and 1.5:1, with crystallization seed of a -dicalcium silicate hydrate;

[0037] b) Hydrothermal treatment of the thus seeded starting material at a temperature between 100 and 300 ° C.

[0038] The process product as disclosed in WO 2007 / 017142, which predominantly consists of a -dicalcium silicate hydrate is also suitable to be used in the present invention.

[0039] In a preferred embodiment the composition comprising calcium silicate hydrate according to the invention is produced by a process wherein

[0040] a) an aqueous solution or suspension of a calcium source is reacted with an aqueous solution or suspension of a silicate source and wherein

[0041] b) the reaction of step a) is made in the presence of at least one water-soluble polymeric dispersant or the at least one water-soluble polymeric dispersant is added after step a) and whereinBASF SE 240796W001

[0042] 5

[0043] c) a composition comprisinga -dicalcium silicate hydrate is introduced before the start of the reaction in step a) or is added during or after step a).

[0044] In a first preferred embodiment step a) is carried out in a closed vessel, for example an autoclave, at a temperature in the range from 100° C to 400° C, in particular from 110 to 300° C or from 110 to 230° C or from 130 to 200° C or from 130 to 180° C or from 155 to 180 or from 160 to 180° C, and a pressure resulting therefrom. In this embodiment the calcium source is a calcium hydroxide source, in particular calcium oxide or calcium hydroxide, it is possible to use, for example, quicklime, slacked lime, etc. and the silicate source is silicon dioxide, in particular silicon dioxide are silica sand or quartz flour, microsilica, etc. Furthermore, pozzolanic binders such as flyashes, slags such as blast furnace slag, and / or metakaolins can also be used as silicon dioxide source. In order to assist the reaction and shorten the reaction time, the starting materials are generally used with an average particle size of < 1 mm. The silicon dioxide source generally has a particle size d(99) in the range from 1 to 100 pm, in particular from 1 to 90 pm. The amount of calcium hydroxide source and the silicon dioxide source is generally selected so that the molar ratio of Ca / Si in the process product in step a) is in the range from 0.5 to 2.5, preferably from 0.8 to 2.2, particularly preferably from 1.0 to 2.0.

[0045] It has been found to be advantageous to use a foaming agent in step a), in particular aluminum powder or a paste comprising metallic aluminum, in the hydrothermal production of the mineral constituent.

[0046] It has been found to be advantageous to comminute the process product from step a) after the hydrothermal synthesis. Conventional apparatuses such as crushers and ball mills are suitable for this purpose. Comminution is carried out until a particle size (d(97)) of < 5 mm, preferably < 2 mm and in particular a particle size (d(97)) in the range from 0.05 mm to 5 mm, preferably from 0.1 mm to 2 mm, in particular from 0.3 mm to 1 mm, is attained. Comminution is carried out at a temperature of < 80 ° C, in particular < 60 ° C, preferably < 50 ° C.

[0047] The process product from step a) according to the first preferred embodiment obtained after the hydrothermal synthesis is preferably firstly subjected to mechanical comminution at a temperature of < 80 ° C, in particular < 60 ° C, preferably < 50 ° C.

[0048] After mechanical comminution, the process product from step a) has a particle size (d(97)) of < 5 mm, preferably < 2.5 mm and in particular < 1 mm. For example, the particle size (d(97)) of the process product from step a) after mechanical comminution is in the range from 0.05 mm to 5 mm, preferably from 0.1 mm to 2 mm, in particular from 0.3 mm to 1 mm.

[0049] The product from step a) preferably has a specific BET surface area in the range from 30 to 150 m2 / g, preferably from 80 to 150, in particular from 90 to 150 m2 / g, particularly preferably from 100 to 150 m2 / g, determined in accordance with DIN ISO 9277:2003-05.BASF SE 240796W001

[0050] 6

[0051] The process in step a) according to the first preferred embodiment of the invention preferably comprises at least 95 wt.-%, more preferably at least 98 wt.-%, based on the dry weight of the process product from step a), of calcium oxide (CaO) and silicon oxide (SiO2). The molar ratio of Ca / Si in the the process product from step a) is preferably in the range from 0.5 to 2.5, more preferably from 0.8 to 2.2, particularly preferably from 1.0 to 2.0 or from 1.6 to 2.0.

[0052] Owing to production-related impurities, the process product from step a) can comprise small amounts of aluminum ions, with the molar ratio of silicon / aluminum in the process product from step a) being from 10 000:1 to 2:1, preferably from 1000:1 to 5:1 and particularly preferably from 100:1 to 10:1.

[0053] The process product from step a) is essentially free of cement, cement clinker and / or ettringite. Here, “essentially free” means less than 10 wt.-% or less than 5 wt.-%, preferably less than 1 wt.-% and in particular 0 wt.-%, in each case based on the total dry weight of the process product from step a).

[0054] Preference is given to no foreign ions such as alkali metal ions, chloride ions or nitrate ions or only a very small amount of foreign ions being introduced into the composition according to the invention via the mineral constituent. In one embodiment, the composition of the invention comprises 2 wt.-% or less of alkali metals, based on the dry weight of the process product from step a).

[0055] In the first preferred embodiment the process product from step a) is obtained by a hydrothermal process with adherence to particular conditions, i.e. by reaction of a calcium hydroxide source, e.g. calcium oxide or calcium hydroxide, with a silicon dioxide source, e.g. silicon dioxide, in the presence of water and at an elevated temperature from 100° C to 400° C and elevated pressure, advantageously in an autoclave. Here, the process product from step a) is obtained as solid with physically adsorbed water. The process product from step a) produced in this way comprises preferably semi-ordered calcium silicate hydrate, crystalline foreign phases including the unreacted crystalline foreign phases or the crystalline foreign phases formed in the reaction, e.g. quartz, portlandite, calcite, etc., and also X-ray-amorphous phases.

[0056] For the purposes of the present invention, “semi-ordered” means that the calcium silicate hydrate has (1) a lower degree of order than a macroscopic crystalline calcium silicate hydrate and (2) a higher degree of order than amorphous calcium silicate hydrate. Semiordered calcium silicate hydrate has physical properties which differ both from the pure crystalline form and from the pure amorphous form.

[0057] One suitable method for determining whether a calcium silicate hydrate is present in semiordered form employs X-ray diffraction. Diffraction patterns of the calcium silicate hydrateBASF SE 240796W001

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[0059] can be recorded using a commercial powder diffractometer. The X-ray diffraction pattern of the semi-ordered calcium silicate hydrate differs from the X-ray diffraction pattern of a crystalline calcium silicate hydrate. Semi-ordered calcium silicate hydrate displays a diffraction pattern in which the reflections or diffraction lines or “peaks” are broader or less well-defined and / or partly absent compared to the diffraction pattern of the crystalline form. In the following, a “peak” is a maximum in the plot of the X-ray diffraction intensity against the diffraction angle. The main diffraction peak of the semi-ordered calcium silicate hydrate has, for example, a width at half height which is at least 1.25 times, usually at least 2 times or at least 3 times, the width at half height of the corresponding main diffraction peak of the crystalline form having a crystallite size of 50 nm or more.

[0060] Furthermore, the X-ray diffraction pattern of the semi-ordered calcium silicate hydrate also differs from the purely X-ray-amorphous form. The X-ray diffraction pattern of the semiordered calcium silicate hydrate displays few broad phase-specific X-ray diffraction maxima which indicate a certain degree of order of the calcium silicate hydrate, while the X-ray-amorphous form displays no distinguishable X-ray diffraction maxima. No calcium silicate hydrate phase can be assigned unambiguously to the X-ray-amorphous form.

[0061] Semi-ordered calcium silicate hydrate has a long-range order of less than 100 repeating units, usually less than 20 repeating units, of the unit cell in at least one direction in space. If the coherently scattering regions (crystallites), which correspond to the repeating units of the unit cell, are very small in a sample, the individual crystallites which are actually present in the reflection plane are often slightly tilted relative to one another. In addition, the disruption of the structure at the grain boundaries results in changes in the diffraction behavior. The angle range in which reflection and thus a diffraction signal still occurs is broadened thereby. An “apparent” crystallite size can be calculated by the method of Scherrer from the widths at half height of X-ray diffraction signals:

[0062] / 3 = A / E cos 9

[0063] / 3 = width at half height

[0064] A = wavelength

[0065] s = apparent crystallite size

[0066] 9 = Bragg angle

[0067] In practice, the “whole pattern fitting structure refinement (PFSR)” of Hugo Rietveld (“Rietveld analysis”) has been found to be useful for evaluating the diffraction pattern. This software method serves to refine a number of measurement parameters, including lattice parameters, signal width and signal shape. Theoretical diffraction patterns can be calculated in this way. As soon as the calculated diffraction pattern is virtually identical to the data of an unknown sample, precise quantitative information as to crystallite size and amorphous content can be determined.BASF SE 240796W001

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[0069] According to the invention, the semi-ordered calcium silicate hydrate has preferably an apparent crystallite size of 15 nm or less, in particular 10 nm or less, preferably 5 nm or less, determined by means of X-ray diffraction analysis and subsequent Rietveld analysis. The apparent crystallite size is preferably at least 1 nm, e.g. from 1 to 15 nm, or from 1 to 10 nm and particularly preferably from 1 nm to 5 nm.

[0070] The unit cells of the ordered regions of the semi-ordered calcium silicate hydrate, the size of which is described with the aid of their apparent crystallite size in the present patent application, are derived from crystalline calcium silicate hydrate phases (C-S-H). Crystalline calcium silicate hydrate phases are, in particular, foshagite, hillebrandite, xonotlite (belovite), xonotlite (kudohite), nekoite, clinotobermorite, 9A - tobermorite (riversiderite), 10A - tobermorite, 11A - tobermorite (C / S 0.75 and 0.66), 14 A - tobermorite (plombierite), jennite, metajennite, calcium chondrodite, afwillite, a - C2SH, del laite, jaffeite, rosenhahnite, killalaite, bultfonteinite, reinhardbraunsite, kilchoanite, C8S5, okenite, reyerite, gyrolith, truscottite, K-phase, Z-phase, scawtite, fukalite, tylleite, spurrite and / or suolunite, preferably as xonotlite, 9A - tobermorite (riversiderite), 11A - tobermorite, 14 A -tobermorite (plombierite), jennite, metajennite, afwillite and / or jaffeite.

[0071] The unit cells of the ordered regions are preferably derived from 9A - tobermorite (riversiderite), 10A - tobermorite, 11A - tobermorite (C / S 0.75 and 0.66), 14 A - tobermorite (plombierite), scawtite and / or xonotlite or mixtures.

[0072] For the present purposes, it has been found to be a sufficient approximation for the determination of the apparent crystallite size to be based exclusively on the unit cell of 14 A - tobermorite (plombierite).

[0073] In an prefered embodiment the process product from step a) comprises a semi-ordered calcium silicate hydrate having an apparent crystallite size of 15 nm or less. The process product from step a) further preferably comprises less than 35% by weight, based on the dry weight of the mineral constituent, of crystalline phases other than the semi-ordered calcium silicate hydrate, i.e. crystalline phases which are not calcium silicate hydrate phase (C-S-H) (hereinafter also: “crystalline foreign phases”). Crystalline foreign phases are portlandite (Ca(OH)2), calcite (CaCO3), aragonite (CaCO3), vaterite (CaCO3) and a -quartz (SiO2). The content of crystalline foreign phases can be in the range from 0.1 to less than 35% by weight, preferably from 1 to 25% by weight, based on the dry weight of the process product from step a). The dry weight is determined by drying the process product from step a) to constant weight at 105°C.

[0074] In the case of contamination with aluminum, the process product from step a) can also comprise aluminum-comprising phases such as gibbsite (AI(OH)3).

[0075] The process product from step a) according to the first preferred embodiment typically also comprises an X-ray-amorphous phase in addition to the semi-ordered calcium silicateBASF SE 240796W001

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[0077] hydrate (and possibly crystalline foreign phases). In one embodiment, the process product from step a) comprises at least > 10% by weight, preferably > 40% by weight, particularly preferably > 60% by weight and in particular from 10 to 99.9% by weight or from 10 to 80% by weight, preferably from 40 to 80% by weight, of X-ray-amorphous phase, based on the dry weight of the process product from step a), determined by means of X-ray diffraction analysis and subsequent Rietveld analysis.

[0078] The sum of semi-ordered calcium silicate hydrate and X-ray-amorphous phase is preferably at least 65% by weight, e.g. from 65 to 99% by weight, based on the dry weight of the process product from step a), determined by means of X-ray diffraction analysis and subsequent Rietveld analysis.

[0079] In the first preferred embodiment the at least one water-soluble polymeric dispersant is preferably added after step a). In one embodiment of the process the process product from step a) is brought into contact with at least one water-soluble polymeric dispersant in an aqueous medium.

[0080] For the contacting with the water-soluble polymeric dispersant, the process product from step a) can be used in the form of a suspension or as dry powder. The water-soluble polymeric dispersant is then added all at once or in two or more portions to the process product from step a), either as solid or in the form of an aqueous solution. However, the process product from step a) is preferably added all at once or in two or more portions as solid or as aqueous suspension to an aqueous solution of the water-soluble polymeric dispersant.

[0081] In the process according to the first embodiment, the weight ratio of calcium silicate hydrate from step a) (calculated as dry component) to water-soluble polymeric dispersant (calculated as dry component) is preferably in the range from 15:1 to 1:3, in particular in the range from 10:1 to 1:1.5, particularly preferably in the range from 5:1 to 1:1. It is further preferred that the composition comprises preferably 24 - 93 wt.-%, more preferably 40 - 88 wt.-%, in particular from 65 - 85 wt.-% of calcium silicate hydrate based on the dry weight of the composition.

[0082] The determination of the dry weight of the composition is carried out by drying the material to constant weight at 105 ° C in a laboratory oven and measuring the resulting loss in weight on drying.

[0083] The water content of the suspension (determined by drying the suspension to constant weight at 105 ° C) in the contacting of the process product from step a) with the water-soluble polymeric dispersant is preferably in the range from 24 wt.-% to 93 wt.-%, in particular in the range from 30 wt.-% to 80 wt.-%, particularly preferably 40 wt.-% to 60 wt.-%.BASF SE 240796W001

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[0085] If desired, the process can be carried out with addition of portland cement, portland cement clinker and / or a latent hydraulic binder, with the proportion by mass of portland cement, portland cement clinker and / or latent hydraulic binder, based on the sum of the amount of process product from step a), being from 0.01 to 10 wt.-%, preferably from 0.01 to 5 wt.-%. The addition can be carried out before contacting with the water-soluble polymeric dispersant, or after mechanical comminution of the mineral constituent.

[0086] In preferred embodiments, the process is carried out essentially without addition of other constituents and in particular essentially without addition of portland cement, portland cement clinker and / or ettringite.

[0087] The contacting of the process product from step a) with the water-soluble polymeric dispersant in step b) according to the first preferred embodiment is carried out preferably with introduction of kinetic energy, for example by mixing or shearing. Virtually all devices known to a person skilled in the art are suitable for this purpose.

[0088] For the purposes of the present invention, mixing is blending or homogenization which intensifies contact of the components to be mixed and thus allows uniform and / or rapid formation of the desired product.

[0089] Methods which effect mixing are, for example, stirring, shaking, injection of gases or liquids and irradiation with ultrasound. Suitable methods and apparatuses which bring about mixing are known to a person skilled in the art. Suitable mixing apparatuses are, for example, stirred vessels, dynamic and static mixers, single-shaft stirring apparatuses, for example stirring apparatuses with scraping devices, in particular paste stirring apparatuses, multishaft stirring apparatuses, in particular PDSM mixers, solids mixers and mixing / kneading reactors.

[0090] In a preferred embodiment, contacting takes place with introduction of shearing energy, with more than 50 kWh, in particular more than 200 kWh, preferably more than 400 kWh, especially from 100 to 5000 kWh, in particular from 200 to 3000 kWh, particularly preferably from 300 to 1000 kWh, of shearing energy being introduced per metric ton of the composition.

[0091] The shearing energy is defined as the effective work Wwwhich can be calculated from the shearing power Pwapplied for milling and the milling time t according to the following equation (1):

[0092] Equation (1): Ww= Pw■ t

[0093] The shearing power which acts on the suspension can be calculated from the difference between effective power Pp(power uptake of the apparatus during milling of the suspension) and the null power Po(power uptake of the apparatus running empty withoutBASF SE 240796W001

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[0095] suspension and if applicable without milling media, e.g. in the case of a bead mill, ball mill or toothed colloid mill) by means of the following equation (2):

[0096] Equation (2): Pw= PP- Po

[0097] The null power (equation (3a)) or the effective power (equation (3b)) can be calculated from the effective voltage U and the effective current I, which is measured by means of a current measuring instrument on the apparatus in operation:

[0098] Equation (3a): Po= Uo- l0■ cos <j> ; cos <j> = 1

[0099] Equation (3b): Pp= UP■ lP■ cos <j> ; cos <j> = 1

[0100] The ratio of effective power Ppto apparent power Psof the apparatus is described by cos <j> according to equation (4):

[0101] Equation (4): cos <j> = Pp / Ps

[0102] Since the apparent power is very apparatus-specific and the effective power can be measured easily (by measuring the effective voltage and the effective current), cos = 1 is assumed in the interests of simplicity.

[0103] Preference is therefore given to processes which introduce a high shearing energy. The process of the invention is therefore particularly preferably carried out for at least part of the time using an apparatus from the group consisting of mills, ultrasonic apparatuses, rotor-stator mixers (e.g. IKA Ultra-Turrax) and high-speed mixers. In particular, the introduction of shearing energy can be carried out by milling, for example in a toothed colloid mill, bead mill, ball mill or preferably stirred ball mill. The stirred ball mill comprises a milling chamber in which the milling media are present, a stator and a rotor which are arranged in the milling chamber. Furthermore, the stirred ball mill preferably comprises an inlet opening for material being milled and an outlet opening for material being milled to effect introduction and discharge of material being milled into or from the milling chamber, and also a milling media separation device which is arranged upstream of the outlet opening in the milling chamber and serves to separate milling media carried with the material being milled from the material being milled before the latter is discharged from the milling space through the outlet opening.

[0104] In order to increase the mechanical milling power introduced into the material being milled in the milling chamber, pins which project into the milling space are preferably present on the rotor and / or on the stator. During operation, a contribution to the milling power is thus firstly produced directly by impacts between the material being milled and the pins.

[0105] Secondly, a further contribution to the milling power is produced indirectly by impacts between the pins and the milling media entrained in the material to be milled and theBASF SE 240796W001

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[0107] subsequent impacts between the material being milled and the milling media. Finally, shear forces and tensile forces acting on the material being milled also contribute to comminution of the suspended particles of the material being milled.

[0108] In one embodiment, the contacting with the water-soluble polymeric dispersant is carried out in two stages. In the first stage, contacting is carried out until the particle size d(99) of the process product from step a) is < 300 pm and in particular is in the range from 0.5 to 300 pm. This can be carried out using an apparatus selected from among a milling apparatus, an ultrasonic apparatus, a rotor-stator mixing system and a high-speed mixer disk.

[0109] In the second stage, step b) is carried out until the process product from step a) has a d(50) particle size of < 800 nm, preferably < 400 nm, particularly preferably < 300 nm, determined by means of static light scattering according to ISO 13320:2020 (analyzed after Mie theory, refractive index = 1.59). This is, in particular, carried out using a milling apparatus.

[0110] It has been found to be advantageous for a rest time of the suspension of from 0.01 hour to 48 hours, preferably from 4 hours to 24 hours, particularly preferably from 6 hours to 16 hours, to be observed before the introduction of kinetic energy, during which time the suspension rests or is stirred in order to prevent sedimentation in a stirred vessel without action of high shearing energy, i.e. shearing energies of < 50 kWh per metric ton of suspension. When the contacting with the water-soluble polymeric dispersant is carried out in two stages, the rest time can be implement before the first stage or between the two stages.

[0111] Before, during or after contacting of the process product from step a) with the dispersant, an acidic compound having preferably a molecular weight from 40 to 99 g / mol, can be added. The addition of acidic compound is preferably carried out after contacting of the process product from step a) with the water-soluble polymeric dispersant has occured. The acidic compound is, for example, selected from among nitric acid, sulfamic acid, methanesulfonic acid, formic acid, acetic acid, sulfuric acid and mixtures thereof, preferably sulfamic acid, methanesulfonic acid, acetic acid and mixtures thereof. The amount of the acidic compound is appropriately selected so that a pH of the suspension of 11.0 - 13.0, preferably 11.4 - 12.5, particularly preferably 11.8 - 12.4, is obtained immediately after the addition of acid (10 to 60 seconds) or after complete homogenization.

[0112] In the scope of the first embodiment it is specifically preferred that a calcium silicate hydrate is brought into contact with at least one water-soluble polymeric dispersant in an aqueous medium by introducing kinetic energy, wherein the calcium silicate hydrate has been produced by reacting calcium oxide or calcium hydroxide with silicon dioxide in the presence of water under hydrothermal conditions at a temperature in the range from 100° C to 400° C for a period of from 1 hours to 30 hours.BASF SE 240796W001

[0113] 13

[0114] In the scope of the first embodiment a composition comprising a -dicalcium silicate hydrate is introduced before the start of the reaction in step a) or is added during or after step a). It is specifically preferred that the composition comprising or consisting of a -dicalcium silicate hydrate is added before step a) as a suspension or in solid form.

[0115] In a further embodiment it is possible to introduce the composition comprising a -dicalcium silicate hydrate after step a) but before step b) or during step b).

[0116] In a further embodiment in the scope of the first embodiment a composition comprising a -dicalcium silicate hydrate is added to the process product after completion of step b). Most preferably the composition comprising a -dicalcium silicate hydrate is added immediately after completion of step b), preferably less than 24 h, in particular less than 1 h after completion of step b). This has the advantage that the viscosity increase of the suspension resulting after step b) is prevented or at least significantly slowed down and the best long-term storage stability can be achieved.

[0117] Surprisingly, it was found that a later addition of a composition comprisinga -dicalcium silicate hydrate after step b) when the viscosity is already above 500 mPa*s or 1000 mPa*s, 1500 mPa*s, 2000 mPa*s, 2500 mPa*s, 3000 mPa*s, 3500 mPa*s, 4000 mPa*s, 4500 mPa*s, 5000 mPa*s, 5500 mPa*s, 6000 mPa*s, 6500 mPa*s in particular above 7000 mPa*s led to a significant reduction of the viscosity of the calcium silicate hydrate composition according to the invention.

[0118] In a second preferred embodiment of the invention, step a) of the process is made in the presence of at least one water-soluble polymeric dispersant. In this embodiment the calcium source in the form of a water-soluble calcium compound is preferably mixed with the aqueous solution which contains at least one water-soluble polymeric dispersant, so that a mixture preferably present as a solution is obtained, to which the silicate source in the form of a water-soluble silicate compound is added in a subsequent second step. The water-soluble silicate compound of the second step can also contain the water-soluble polymeric dispersant.

[0119] The aqueous solution may also contain one or more further solvents (for example alcohols like ethanol and / or isopropanol) in addition to water. Preferably the weight proportion of the solvent other than water to the sum of water and further solvent (e.g. alcohol) is up to 20 wt.-%, more preferably less than 10 wt.-% and most preferably less than 5 wt.-%. However most preferable are aqueous systems without any solvent.

[0120] The temperature range in which the process according to the second preferred embodiment is carried out is not especially limited. Certain limits however are imposed by the physical state of the system. It is preferable to work in the range of 0 to 100 ° C, more preferable 5 to 80 ° C and most preferable 15 to 35 ° C. High temperatures can be reached especially when a milling process is applied. It is preferable not to exceed 80 ° C.BASF SE 240796W001

[0121] 14

[0122] Also, the process can be carried out at different pressures, preferably in a range of 1 to 5 bars.

[0123] The pH-value depends on the quantity of reactants (water-soluble calcium compound and water-soluble silicate) and on the solubility of the precipitated calcium silicate hydrate. It is preferable that the pH value is higher than 8 at the end of the synthesis, preferably in a range between 8 and 13.5.

[0124] In a further preferred embodiment within the scope of the second preferred embodiment, the aqueous solution containing the water-soluble polymeric dispersant is provided and the water-soluble calcium compound and the water-soluble silicate compound are added simultaneously. This means that the reaction of the water-soluble calcium compound and the water-soluble silicate compound in order to precipitate calcium silicate hydrate occurs in the presence of an aqueous solution which contains the water-soluble polymeric dispersant according to this invention.

[0125] A further preferred embodiment within the scope of the second preferred embodiment is characterized in that a solution of a water-soluble calcium compound and a solution of a water-soluble silicate compound are added preferably separately to the aqueous solution containing the water-soluble polymeric dispersant.

[0126] To illustrate how this aspect of the invention can be carried out, for example three solutions can be prepared separately (solution (I) of a water-soluble calcium compound, solution (II) of a water-soluble silicate compound and a solution (III) of the water-soluble polymeric dispersant). Solutions (I) and (II) are preferably separately and simultaneously added to solution (III). Advantage of this preparation method is besides its good practicability that relatively small particle sizes can be obtained.

[0127] In a further preferred embodiment of the invention the previous standing embodiment can be modified in that the solution of a water soluble calcium compound and / or the solution of a water-soluble silicate compound contain the water-soluble polymeric dispersant. In this case the method is carried out in principle in the same way as described in the previous embodiment, but solution (I) and / or solution (II) preferably contain also the water-soluble polymeric dispersant. In this case the person skilled in the art will understand that the water-soluble polymeric dispersant is distributed to at least two or three solutions. It is advantageous that 1 to 50 wt.-%, preferably 10 to 25 wt.-% of the total of the water-soluble polymeric dispersant are contained in the calcium compound solution (e.g. solution (I)) and / or silicate compound solution (e.g. solution (II)). This preparation method has the advantage that the water-soluble polymeric dispersant is present also in the solution of the water-soluble calcium compound and / or the solution of the water-soluble silicate compound.BASF SE 240796W001

[0128] 15

[0129] In a further preferred embodiment of the invention the previous embodiment can be modified in that the aqueous solution containing water-soluble polymeric dispersant contains a water-soluble calcium compound or a water-soluble silicate compound.

[0130] In this case the method is carried out in principle in the same way as described in the previous embodiment, but solution (III) would contain a water-soluble calcium compound or a water-soluble silicate compound. In this case the person skilled in the art will understand that the water-soluble calcium compound or the water-soluble silicate compound is distributed to at least two solutions.

[0131] In a preferred embodiment the process is characterized in that the addition of the water-soluble calcium compound and of the water-soluble silicate compound to the aqueous solution containing the water-soluble polymeric dispersant is carried out in a cyclic semibatch process with a first and a second reactor in series, the second reactor containing initially an aqueous solution of the water-soluble polymeric dispersant, the first reactor being fed with the solution of the water-soluble silicate compound, the solution of the water-soluble calcium compound and with the contents of the second reactor and the outflow of the first reactor being added to the second reactor or characterized in that said addition is carried out in a continuous process in which the water-soluble calcium compound, the water-soluble silicate compound and the aqueous solution which contains the water-soluble polymeric dispersant are mixed in the first reactor and the resulting outflow is fed into a mixed flow reactor or into a plug flow reactor.

[0132] Preferably the ratio of the volumes of the first and second reactor is from 1 / 10 to 1 / 20.000. Preferably the mass flow rate of the water-soluble calcium and water-soluble silicate compounds is small compared to the mass flow leaving the second and entering the first reactor, preferably the ratio is from 1 / 5 to 1 / 1000. Typically, the first reactor can be a static or a dynamic mixing unit, preferably the mixing in the first reactor should be effective.

[0133] In the scope of the second preferred embodiment, the components are used in the following ratios:

[0134] i) 0.01 to 75, preferably 0.01 to 51, most preferably 0.01 to 15 % by weight of water-soluble calcium compound,

[0135] ii) 0.01 to 75, preferably 0.01 to 55, most preferably 0.01 to 10 % by weight of water-soluble silicate compound,

[0136] iii) 0.001 to 60, preferably 0.1 to 30, most preferably 0.1 to 10 % by weight of the water-soluble polymeric dispersant,

[0137] iv) 24 to 99, preferably 50 to 99, most preferably 70 to 99 % by weight of water.

[0138] Often, the water-soluble calcium compound is present as calcium chloride, calcium nitrate, calcium formate, calcium acetate, calcium bicarbonate, calcium bromide, calcium carbonate, calcium citrate, calcium chlorate, calcium fluoride, calcium gluconate, calcium hydroxide, calcium hypochloride, calcium iodate, calcium iodide, calcium lactate, calciumBASF SE 240796W001

[0139] 16

[0140] nitrite, calcium oxalate, calcium phosphate, calcium propionate, calcium silicate, calcium stearate, calcium sulphate, calcium sulphate hemihydrate, calcium sulphate dihydrate, calcium sulphide, calcium tartrate calcium aluminate, tricalcium silicate and / or dicalcium silicate. Preferably the water-soluble calcium compound is not a calcium silicate. The silicates calcium silicate, dicalcium silicate and / or tricalcium silicate are less preferred because of low solubility (especially in the case of calcium silicate) and for economic reasons (price) (especially in case of dicalcium silicate and tricalcium silicate).

[0141] The water-soluble calcium compound is preferably present as calcium citrate, calcium tartrate, calcium formate and / or calcium sulphate. Advantage of these calcium compounds is their non-corrosiveness. Calcium citrate and / or calcium tartrate are preferably used in combination with other calcium sources because of the possible retarding effect of these anions when used in high concentrations.

[0142] In a further embodiment of the invention the calcium compound is present as calcium chloride and / or calcium nitrate. Advantage of these calcium compounds is their good solubility in water, low price and good availability.

[0143] Often, the water-soluble silicate compound is present as sodium silicate, potassium silicate, waterglass, aluminium silicate, tricalcium silicate, dicalcium silicate, calcium silicate, silicic acid, sodium metasilicate and / or potassium metasilicate.

[0144] The water-soluble silicate compound is preferably present as sodium metasilicate, potassium metasilicate and / or waterglass. Advantage of these silicate compounds is their extremely good solubility in water.

[0145] Preferably species of different types are used as the water-soluble silicate compound and as the water-soluble calcium compound.

[0146] In a preferable process water-soluble alkali metal ions (for example lithium, sodium, potassium) are removed from the hardening accelerator composition by cation exchangers and / or water-soluble nitrate and / or chloride ions are removed from the hardening accelerator composition by anion exchangers. Preferably the removal of said cations and / or anions is carried out in a second process step after the preparation of the hardening accelerator composition by the use of the ion exchangers. Acid ion exchangers suitable as cation exchanger are for example based on sodium polystyrene sulfonate or poly-2-acrylamido-2-methylpropane sulfonic acid (poly AMPS). Basic ion exchangers are for example based on amino groups, like for example poly (acrylamido-N-propyltrimethylammonium chloride) (poly APTAC).

[0147] In the scope of the second preferred embodiment a composition comprisinga -dicalcium silicate hydrate is introduced before the start of the reaction in step a) or is added during orBASF SE 240796W001

[0148] 17

[0149] after step a). It is specifically preferred that the composition comprising or consisting of a -dicalcium silicate hydrate is added before step a) as a suspension or in solid form.

[0150] In a further embodiment in the scope of the second embodiment a composition comprising a -dicalcium silicate hydrate is added to the process product after completion of step a). Most preferably the composition comprising a -dicalcium silicate hydrate is added immediately after completion of step a), preferably less than 24 h, in particular less than 1 h after completion of step a). This has the advantage that the viscosity increase of the suspension resulting after step a) is prevented or at least significantly slowed down and the best long-term storage stability can be achieved.

[0151] Surprisingly, it was found that a later addition of a composition comprisinga -dicalcium silicate hydrate after step a) when the viscosity is already above 500 mPa*s or 1000 mPa*s, 1500 mPa*s, 2000 mPa*s, 2500 mPa*s, 3000 mPa*s, 3500 mPa*s, 4000 mPa*s, 4500 mPa*s, 5000 mPa*s, 5500 mPa*s, 6000 mPa*s, 6500 mPa*s in particular above 7000 mPa*s led to a significant reduction of the viscosity of the calcium silicate hydrate composition according to the invention.

[0152] The invention further concerns in a third preferred embodiment for producing a composition comprising calcium silicate hydrate by reaction of a calcium compound, preferably a calcium salt, most preferably a water-soluble calcium salt with a silicon dioxide containing component under alkaline conditions characterized in that the reaction is carried out in the presence of an aqueous solution of a water-soluble polymeric dispersant.

[0153] Typically the calcium compounds are calcium salts (e.g. calcium salts of carboxylic acids). The calcium salt can be for example calcium chloride, calcium nitrate, calcium formate, calcium acetate, calcium bicarbonate, calcium bromide, calcium carbonate, calcium citrate, calcium chlorate, calcium fluoride, calcium gluconate, calcium hydroxide, calcium oxide, calcium hypochloride, calcium iodate, calcium iodide, calcium lactate, calcium nitrite, calcium oxalate, calcium phosphate, calcium propionate, calcium silicate, calcium stearate, calcium sulphate, calcium sulphate hemihydrate, calcium sulphate dihydrate, calcium sulphide, calcium tartrate, calcium aluminate, tricalcium silicate and / or dicalcium silicate. Preferable are calcium hydroxide and / or calcium oxide because of their strong alkaline properties. Preferably the water-soluble calcium compound is not a calcium silicate. The silicates calcium silicate, dicalcium silicate and / or tricalcium silicate are less preferred because of low solubility (especially in the case of calcium silicate) and for economic reasons (price) (especially in case of dicalcium silicate and tricalcium silicate). Less preferable are also not so good soluble calcium salts like for example calcium carbonate and also calcium salts with retarding anions (e.g. citrate, gluconate, tartrate can retard the hardening of hydraulic binders). In the case of neutral or acid calcium salts (e.g. calcium chloride or calcium nitrate) it is preferable to use a suitable base to adjust the pH-value to alkaline conditions (e.g. lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, magnesium hydroxide or any other earth alkali hydroxide). Preferable is a pH-BASF SE 240796W001

[0154] 18

[0155] value higher than 8, more preferable higher than 9 and most preferable higher than 11. The pH-value is measured preferably at 25 ° C and with a solid content of the suspension of 1 weight %.

[0156] It is possible to use any material which contains silicon dioxide, for example microsilica, pyrogenic silica, precipitated silica, blast furnace slag and / or quartz sand. Small particle sizes of the silicon dioxide containing material are preferable, especially particle sizes below 1 pm. Further it is possible to use compounds which are able to react in an aqueous alkaline environment to silicon dioxide like for example tetraalkoxy silicon compounds of the general formula Si(OR)4. R can be the same or different and can be for example selected from a branched or non-branched Cl to CIO alkyl group. Preferably R is methyl, especially preferably ethyl.

[0157] In the scope of the third preferred embodiment the silicon dioxide containing compound is preferably selected from the group of microsilica, pyrogenic silica, precipitated silica, blast furnace slag and / or quartz sand. Preferable are microsilica, pyrogenic silica and / or precipitated silica, especially precipitated and / or pyrogenic silica. The types of silica, which are listed above are defined in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Release 2009, 7thEdition, DOI 10.1002 / 14356007.a23_583.pub3.

[0158] It is preferable to apply mechanical energy, preferably by milling, to the reaction mixture in order to activate and / or accelerate the reaction of the calcium salt with the usually low water-soluble silicon dioxide containing component. The mechanical energy is also advantageous in order to reach the desired small particle sizes of the calcium silicate hydrates. The wording “milling" means in this embodiment any process in which high shear forces are exerted on the reaction mixture in order to accelerate the reaction and to obtain a suitable particle size. For example milling can be carried out in a planet ball mill in a continuous or batch operation mode. Alternatively, an ultradisperser, preferably with a number of revolutions higher than 5.000 r.p.m. can be used. Also it is possible to apply a so-called shaker equipment in which small grinding bodies, preferably smaller than 1 mm in diameter are put together with the reaction mixture into a receptacle and are shaken. The respective shaker equipment is for example available from the company Skandex.

[0159] Typically the pH-value in the third preferred embodiment for producing the composition comprising calcium silicate hydrate is higher than 9.

[0160] Preferably the molar ratio of calcium from the calcium compound to silicon from the silicon dioxide containing component is from 0.6 to 2, preferably 1.1 to 1.8.

[0161] In the scope of the third embodiment a composition comprising a -dicalcium silicate hydrate is introduced before the start of the reaction in step a) or is added during or after step a). It is specifically preferred that the composition comprising or consisting of a -dicalcium silicate hydrate is added before step a) as a suspension or in solid form.BASF SE 240796W001

[0162] 19

[0163] In a further embodiment in the scope of the third preferred embodiment a composition comprisinga -dicalcium silicate hydrate is added to the process product after completion of step a). Most preferably the composition comprising a -dicalcium silicate hydrate is added immediately after completion of step a), preferably less than 24 h, in particular less than 1 h after completion of step a). This has the advantage that the viscosity increase of the suspension resulting after step a) is prevented or at least significantly slowing down and the best long-term storage stability can be achieved.

[0164] Surprisingly, it was found that a later addition of a composition comprisinga -dicalcium silicate hydrate after step a) when the viscosity is already above 500 mPa*s or 1000 mPa*s, 1500 mPa*s, 2000 mPa*s, 2500 mPa*s, 3000 mPa*s, 3500 mPa*s, 4000 mPa*s, 4500 mPa*s, 5000 mPa*s, 5500 mPa*s, 6000 mPa*s, 6500 mPa*s in particular above 7000 mPa*s led to a significant reduction of the viscosity of the calcium silicate hydrate composition according to the invention.

[0165] In an alternative preferred embodiment, the -dicalcium silicate hydrate is simultaneously formed as a process product during the production of the calcium silicate hydrate in a hydrothermal process. Step a) of the process is carried out in a closed vessel, for example an autoclave, at a temperature in the range from 100° C to 400° C, in particular from 110 to 300° C or from 110 to 230° C or from 130 to 200° C or from 130 to 180° C or from 155 to 180 or from 160 to 180° C, and a pressure resulting therefrom. In this embodiment the calcium source is a calcium hydroxide source, in particular calcium hydroxide, preferably as slacked lime suspension, and calcium oxide. The silicate source is silicon dioxide, in particular silicon dioxide are silica sand or quartz flour, microsilica, etc. Furthermore, pozzolanic binders such as flyashes, slags such as blast furnace slag, and / or metakaolins can also be used as silicon dioxide source. In order to assist the reaction and shorten the reaction time, the starting materials are generally used with an average particle size of < 1 mm. The silicon dioxide source generally has a particle size d(99) in the range from 1 to 100 pm, in particular from 1 to 90 pm. The total amount of calcium source and the silicon dioxide source is generally selected so that the molar ratio of Ca / Si in the process product in step a) is in the range from 0.5 to 2.5, preferably from 0.8 to 2.2, particularly preferably from 1.0 to 2.0. To assist the reaction a -dicalcium silicate hydrate seeds can be added to the reaction mixture. It is preferred that the composition comprises 0.005 - 10 wt.-%, more preferably 0.01 - 3 wt.-% and in particular from 0.02 - 1.2 wt.-% a -dicalcium silicate hydrate seeds based on the dry weight of the composition.

[0166] In step b) of the process the product of step a) is brought into contact with at least one water-soluble polymeric dispersant in an aqueous medium. The contacting of the process product from step a) with the water-soluble polymeric dispersant in step b) is carried out preferably with introduction of kinetic energy, for example by mixing or shearing. Virtually all devices known to a person skilled in the art are suitable for this purpose.BASF SE 240796W001

[0167] 20

[0168] Methods which effect mixing are, for example, stirring, shaking, injection of gases or liquids and irradiation with ultrasound. Suitable methods and apparatuses which bring about mixing are known to a person skilled in the art. Suitable mixing apparatuses are, for example, stirred vessels, dynamic and static mixers, single-shaft stirring apparatuses, for example stirring apparatuses with scraping devices, in particular paste stirring apparatuses, multishaft stirring apparatuses, in particular PDSM mixers, solids mixers and mixing / kneading reactors.

[0169] In a preferred embodiment, contacting takes place with introduction of shearing energy, with more than 50 kWh, in particular more than 200 kWh, preferably more than 400 kWh, especially from 100 to 5000 kWh, in particular from 200 to 3000 kWh, particularly preferably from 300 to 1000 kWh, of shearing energy being introduced per metric ton of the composition.

[0170] Preference is therefore given to processes which introduce a high shearing energy. The process is therefore particularly preferably carried out for at least part of the time using an apparatus from the group consisting of mills, ultrasonic apparatuses, rotor-stator mixers (e.g. IKA Ultra-Turrax) and high-speed mixers. In particular, the introduction of shearing energy can be carried out by milling, for example in a toothed colloid mill, bead mill, ball mill or preferably stirred ball mill. The stirred ball mill comprises a milling chamber in which the milling media are present, a stator and a rotor which are arranged in the milling chamber. Furthermore, the stirred ball mill preferably comprises an inlet opening for material being milled and an outlet opening for material being milled to effect introduction and discharge of material being milled into or from the milling chamber, and also a milling media separation device which is arranged upstream of the outlet opening in the milling chamber and serves to separate milling media carried with the material being milled from the material being milled before the latter is discharged from the milling space through the outlet opening.

[0171] In order to increase the mechanical milling power introduced into the material being milled in the milling chamber, pins which project into the milling space are preferably present on the rotor and / or on the stator. During operation, a contribution to the milling power is thus firstly produced directly by impacts between the material being milled and the pins.

[0172] Secondly, a further contribution to the milling power is produced indirectly by impacts between the pins and the milling media entrained in the material to be milled and the subsequent impacts between the material being milled and the milling media. Finally, shear forces and tensile forces acting on the material being milled also contribute to comminution of the suspended particles of the material being milled.

[0173] In one embodiment, the contacting with the water-soluble polymeric dispersant is carried out in two stages. In the first stage, contacting is carried out until the particle size d(99) of the process product from step a) is < 300 pm and in particular is in the range from 0.5 to 300 pm. This can be carried out using an apparatus selected from among a millingBASF SE 240796W001

[0174] 21

[0175] apparatus, an ultrasonic apparatus, a rotor-stator mixing system and a high-speed mixer disk.

[0176] In the second stage, step b) is carried out until the process product from step a) has a d(50) particle size of < 800 nm, preferably < 400 nm, particularly preferably < 300 nm, determined by means of static light scattering according to ISO 13320:2020 (analyzed after Mie theory, refractive index = 1.59). This is, in particular, carried out using a milling apparatus.

[0177] It has been found to be advantageous for a rest time of the suspension of from 0.01 hour to 48 hours, preferably from 4 hours to 24 hours, particularly preferably from 6 hours to 16 hours, to be observed before the introduction of kinetic energy, during which time the suspension rests or is stirred in order to prevent sedimentation in a stirred vessel without action of high shearing energy, i.e. shearing energies of < 50 kWh per metric ton of suspension. When the contacting with the water-soluble polymeric dispersant is carried out in two stages, the rest time can be implement before the first stage or between the two stages.

[0178] Before, during or after contacting of the process product from step a) with the dispersant, an acidic compound having preferably a molecular weight from 40 to 99 g / mol, can be added. The addition of acidic compound is preferably carried out after contacting of the process product from step a) with the water-soluble polymeric dispersant has occured. The acidic compound is, for example, selected from among nitric acid, sulfamic acid, methanesulfonic acid, formic acid, acetic acid, sulfuric acid and mixtures thereof, preferably sulfamic acid, methanesulfonic acid, acetic acid and mixtures thereof. The amount of the acidic compound is appropriately selected so that a pH of the suspension of 11.0 - 13.0, preferably 11.4 - 12.5, particularly preferably 11.8 - 12.4, is obtained immediately after the addition of acid (10 to 60 seconds) or after complete homogenization.

[0179] In the scope of this embodiment the invention further concerns a process for producing a composition comprising calcium silicate hydrate, wherein calcium silicate hydrate is brought into contact with at least one water-soluble polymeric dispersant in an aqueous medium by introducing kinetic energy, wherein the calcium silicate hydrate comprising a -dicalcium silicate hydrate has been produced by reacting calcium oxide with silicon dioxide, wherein the molar ratio of Ca / Si in the range from 0.5 to 2.5, preferably from 0.8 to 2.2, particularly preferably from 1.0 to 2.0, in the presence of water under hydrothermal conditions at a temperature in the range from 100° C to 300° C, in particular from 110 to 300° C or from 110 to 230° C or from 130 to 200° C or from 130 to 180° C or from 155 to 180 or from 160 to 180° C, for a period of from 1 hours to 30 hours, preferably from 4 hours to 24 hours, particularly preferably from 6 hours to 16 hours, wherein from 1 to 90 wt.-%, preferably from 1.5 to 89 wt.-%, in particular from 2 to 88 wt.-% or from 2.5 to 86 wt.-% or from 3 to 84 wt.-% or from 3.5 to 82 wt.-% or from 4 to 80 wt.-% of the total CaO is slaked with water in a separate reaction to form calcium hydroxide and introduced into the reaction mixture prior to the hydrothermal reaction.BASF SE 240796W001

[0180] 22

[0181] In an alternative preferred embodiment from 1 to 50 wt.-%, preferably from 1 to 30 wt.-%, in particular from 1 to 25 wt.-% or from 1.5 to 20 wt.-% or from 1.5 to 15 wt.-% or from 2 to 12 wt.-% or from 3 to 11 wt.-% or from 5 to 10 wt.-% of the total CaO is slaked with water in a separate reaction to form calcium hydroxide and introduced into the reaction mixture prior to the hydrothermal reaction.

[0182] In an preferred embodiment the slaked CaO is in the form of a lime milk or hydrated lime slurry, most preferably a lime milk.

[0183] The water-soluble polymeric dispersant according to the invention preferably comprises at least two monomer units. It may also, however, be advantageous to use copolymers having three or more monomer units.

[0184] “Water-soluble polymers” in the sense of the present specification are polymers which in water at 20° C under atmospheric pressure have a solubility of at least 1 gram per liter, more particularly at least 10 grams per liter, and very preferably of at least 100 grams per liter.

[0185] In one preferred embodiment, said at least one water-soluble polymeric dispersant comprises polyether groups of the structural unit (I)

[0186] *-U-(C(O))k-X-(AlkO)n-W (I)

[0187] where

[0188] * indicates the bonding site to the polymer,

[0189] U is a chemical bond or an alkylene group having 1 to 8 carbon atoms,

[0190] X is oxygen, sulfur or a group NR1,

[0191] k is 0 or 1,

[0192] n is an integer whose average value based on the polymer is in the range from 3 to 300, Aik is C2-C4alkylene, it being possible for Aik to be identical or different within the group (Alk-O)n,

[0193] W is a hydrogen, a Cx-C6alkyl or an aryl radical or is the group Y-F, where

[0194] Y is a linear or branched alkylene group having 2 to 8 carbon atoms and may carry a phenyl ring,

[0195] F is a 5- to 10-membered nitrogen heterocycle which is bonded via nitrogen and which as ring members, besides the nitrogen atom and besides carbon atoms, may have 1, 2 or 3 additional heteroatoms, selected from oxygen, nitrogen, and sulfur, it being possible for the nitrogen ring members to have a group R2, and for 1 or 2 carbon ring members to be present in the form of a carbonyl group,

[0196] R1is hydrogen, Cx-C4alkyl or benzyl, and

[0197] R2is hydrogen, Cj-C4alkyl or benzyl.BASF SE 240796W001

[0198] 23

[0199] With particular preference, the water-soluble polymeric dispersant of the invention comprises at least one group from the series of carboxyester, carboxyl, phosphono, sulfino, sulfo, sulfamido, sulfoxy, sulfoalkyloxy, sulfinoalkyloxy, and phosphonooxy group.

[0200] With more particular preference, the water-soluble polymeric dispersant of the invention comprises an acid group.

[0201] The term “acid group” is understood in the present specification to refer both to the free acid and to the salts thereof. The acid may preferably be at least one from the series of carboxyl, phosphono, sulfino, sulfo, sulfamido, sulfoxy, sulfoalkyloxy, sulfinoalkyloxy, and phosphonooxy group. Particularly preferred are carboxyl and phosphonooxy groups.

[0202] In one particularly preferred embodiment, the water-soluble polymeric dispersant comprises a polycondensation product comprising

[0203] (II) a structural unit comprising an aromatic or heteroaromatic group and the polyether group, and

[0204] (III) a phosphated structural unit comprising an aromatic or heteroaromatic group.

[0205] The structural units (II) and (III) are preferably represented by the following general formulae

[0206] (II) A-U-(C(O))k-X-(AlkO)n-W

[0207] where

[0208] A is identical or different and is represented by a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbons in the aromatic system, the other radicals possessing the definition stated for structural unit (I);

[0209] (III)

[0210]

[0211] where

[0212] D is identical or different and is represented by a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbons in the aromatic system.

[0213] Furthermore, E is identical or different and is represented by N, NH or 0,BASF SE 240796W001

[0214] 24

[0215] m = 2 if E = N and m = 1 if E = NH or O.

[0216] R3and R4independently of one another are identical or different and are represented by a branched or unbranched Cxto C10alkyl radical, C5to C8cycloalkyl radical, aryl radical, heteroaryl radical or H, preferably by H, methyl, ethyl or phenyl, more preferably by H or methyl, and especially preferably by H. Furthermore, b is identical or different and is represented by an integer from 0 to 300. If b = 0, E = O. More preferably D = phenyl, E = O, R3and R4= H, and b = 1.

[0217] The polycondensation product preferably comprises a further structural unit (IV) which is represented by the following formula

[0218]

[0219] where

[0220] Y independently at each occurrence is identical or different and is represented by (II), (III) or further constituents of the polycondensation product.

[0221] R5and R6are preferably identical or different and represented by H, CH3, COOH or a substituted or unsubstituted, aromatic or heteroaromatic compound having 5 to 10 carbons. R5and R6here in structural unit (IV) are independently of one another preferably represented by H, COOH and / or methyl.

[0222] In one particular preferred embodiment, R5and R6are represented by H.

[0223] The molar ratio of the structural units (II), (III), and (IV) in the phosphated polycondensation product of the invention may be varied within wide ranges. It has proven useful for the molar ratio of the structural units [(II) + (III)]: (IV) to be 1:0.8 to 3, preferably 1:0.9 to 2, and more preferably 1:0.95 to 1.2.

[0224] The molar ratio of the structural units (II): (III) is normally 1:10 to 10:1, preferably 1:7 to 5:1, and more preferably 1:5 to 3:1.

[0225] The groups A and D in the structural units (II) and (III) in the polycondensation product are usually represented by phenyl, 2-hydroxyphenyl, 3-hydroxyphenyl, 4-hydroxyphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, naphthyl, 2-hydroxynaphthyl,

[0226] 4-hydroxynaphthyl, 2-methoxynaphthyl, 4-methoxynaphthyl, preferably phenyl, and A and D may be selected independently of one another and may also each consist of a mixture of the stated compounds. The groups X and E are represented independently of one another preferably by O.BASF SE 240796W001

[0227] 25

[0228] Preferably, n in structural unit (I) is represented by an integer from 5 to 280, more particularly 10 to 160, and very preferably 12 to 120, and b in structural unit (III) is represented by an integer from 0 to 10, preferably 1 to 7, and more preferably 1 to 5. The representative radicals whose length is defined by n and b may consist here of uniform structural groups, though it may also be useful for them to comprise a mixture of different structural groups. Furthermore, the radicals of the structural units (II) and (III) may independently of one another each have the same chain length, with n and b in each case being represented by one number. In general, however, it will be useful for these each to be mixtures having different chain lengths, and so the radicals of the structural units in the polycondensation product have different numerical values for n and, independently for b.

[0229] In one particular embodiment, the present invention further envisages a sodium, potassium, ammonium and / or calcium salt, and preferably a sodium and / or potassium salt, of the phosphated polycondensation product.

[0230] The phosphated polycondensation product of the invention frequently has a weight-average molecular weight of 5000 g / mol to 150 000 g / mol, preferably 10 000 to 100 000 g / mol, and more preferably 20 000 to 75 000 g / mol.

[0231] With regard to the phosphated polycondensation products for preferred use in accordance with the present invention, and to their preparation, reference is additionally made to patent applications WO 2006 / 042709 and WO 2010 / 040612, the content of which is hereby incorporated into the specification.

[0232] In a further preferred embodiment, the water-soluble polymeric dispersant comprises at least one copolymer which is obtainable by polymerization of a mixture of monomers comprising

[0233] (V) at least one ethy lenically unsaturated monomer which comprises at least one radical from the series of carboxylic acid, carboxylic salt, carboxylic ester, carboxylic amide, carboxylic anhydride, and carboxylic imide

[0234] and

[0235] (VI) at least one ethylenically unsaturated monomer comprising a polyether group, the polyether group being represented preferably by the structural unit (I).

[0236] The copolymers in accordance with the present invention contain at least two monomer units. It may, however, also be advantageous to use copolymers having three or more monomer units.

[0237] In one preferred embodiment, the ethylenically unsaturated monomer (V) is represented by at least one of the following general formulae from the group of (Va), (Vb), and (Vc):BASF SE 240796W001

[0238]

[0239] In the monocarboxylic or dicarboxylic acid derivative (Va) and in the monomer (Vb) present in cyclic form, where Z = 0 (acid anhydride) or NR16(acid imide), R7and R8independently of one another are hydrogen or an aliphatic hydrocarbon radical having 1 to 20 carbons, preferably a methyl group. B is H, -COOMa, -CO-O(CqH2qO)r-R9, -CO-NH-(CqH2qO)r-R9.

[0240] M is hydrogen, a mono- or di- or trivalent metal cation, preferably sodium, potassium, calcium or magnesium ion, or else ammonium or an organic amine radical, and a = 1 / 3, 1 / 2 or 1, according to whether M is a mono-, di- or trivalent cation. Organic amine radicals used are preferably substituted ammonium groups which derive from primary, secondary or tertiary alkylamines,

[0241]

[0242] alkanolamines, C5.8cycloalkylamines, and C6.14arylamines. Examples of the corresponding amines are methylamine, dimethylamine, trimethylamine, ethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, cyclohexylamine, dicyclohexylamine, phenylamine, diphenylamine in the protonated (ammonium) form.

[0243] R9is hydrogen, an aliphatic hydrocarbon radical having 1 to 20 carbons, a cycloaliphatic hydrocarbon radical having 5 to 8 carbons, an aryl radical having 6 to 14 carbons, this radical optionally being substituted as well, q = 2, 3 or 4 and r = 0 to 200, preferably 1 to 150. The aliphatic hydrocarbons here may be linear or branched and also saturated or unsaturated. Preferred cycloalkyl radicals are cyclopentyl or cyclohexyl radicals, and preferred aryl radicals are phenyl or naphthyl radicals, which in particular may also be substituted by hydroxyl, carboxyl or sulfonic acid groups.

[0244] Furthermore, Z is O or NR16, where R16independently of each occurrence is identical or different and is represented by a branched or unbranched Cxto C10alkyl radical, C5to C8cycloalkyl radical, aryl radical, heteroaryl radical or H.

[0245] The following formula represents the monomer (Vc):

[0246]

[0247] BASF SE 240796W001

[0248] 27

[0249] In this formula, R10and R11independently of one another are hydrogen or aliphatic hydrocarbon radical having 1 to 20 carbons, a cycloaliphatic hydrocarbon radical having 5 to 8 carbons, an optionally substituted aryl radical having 6 to 14 carbons.

[0250] Furthermore, R12is identical or different and is represented by (CnH2n)-SO3H with n = 0, 1, 2, 3 or 4, (CnH2n)-OH with n = 0, 1, 2, 3 or 4; (CnH2n)-PO3H2with n = 0, 1, 2, 3 or 4, (CnH2n)-OPO3H2with n= 0, 1, 2, 3 or 4, (C6H4)-SO3H, (C6H4)-PO3H2, (C6H4)-OPO3H2and

[0251] (CnH2n)-NR14bwith n = 0, 1, 2, 3 or 4 and b by 2 or 3.

[0252] R13is H, -C00Ma, -CO-O(CqH2qO)r-R9, -CO-N H-(CqH2qO)r-R9, where Ma, R9, q and r possess the definitions stated above.

[0253] R14is hydrogen, an aliphatic hydrocarbon radical having 1 to 10 carbons, a cycloaliphatic hydrocarbon radical having 5 to 8 carbons, an optionally substituted aryl radical having 6 to 14 carbons.

[0254] Furthermore, Q is identical or different and is represented by NH, NR15or O, where R15is an aliphatic hydrocarbon radical having 1 to 10 carbons, a cycloaliphatic hydrocarbon radical having 5 to 8 carbons or an optionally substituted aryl radical having 6 to 14 carbons.

[0255] In one particularly preferred embodiment, the ethylenically unsaturated monomer (VI) is represented by the following general formulae (Via)

[0256] (Via)

[0257]

[0258] >

[0259] in which all the radicals having the definitions above.

[0260] In a further-preferred embodiment, the ethylenically unsaturated monomer (VI) is represented by the following general formulae (Vlb)

[0261]

[0262] BASF SE 240796W001

[0263] 28

[0264] where

[0265] R1, R2, R3independently of one another, identically or differently, are H, CH3,

[0266] R4is linear or branched alkylene,

[0267] R5, R6independently of one another, identically or differently, are H, Cj-C^ alkyl, C3- C15cycloalkyl, aryl, -CH^O-C C^ alkyl, CH2-O-C2-C20alkenyl, and R5and R6may also together form a C3-C6alkylene,

[0268] R7independently at each occurrence, identically or differently, is H, C!-C4alkyl,

[0269] O

[0270] — C-R8

[0271] R8is Ci-022 alkyl, C2-C22alkenyl, and

[0272] n independently at each occurrence, is identical or different and is an integer from 2 to 200.

[0273] In particular, the copolymer has an average molar weight (Mw) of between 5000 and 150 000 g / mol, more preferably 10 000 to 80 000 g / mol, and very preferably 15 000 to 60 000 g / mol, as determined by gel permeation chromatography.

[0274] The polymers are analyzed for average molar mass and conversion by means of size exclusion chromatography (column combinations: Shodex OH-Pak SB 804 HQ and OH-Pak SB 802.5 HQ from Showa Denko, Japan; eluent: 80 vol% aqueous solution of HCO2NH4(0.05 mol / l) and 20 vol-% MeOH; injection volume 100 pl; flow rate 0.5 ml / min).

[0275] The preparation of the comb polymers which comprise the structural units (V) and (VI) is carried out in a conventional way, for example by free-radical polymerization. It is, for example, described in EP0894811, EP1851256, EP2463314, EP0753488.

[0276] The copolymer of the invention preferably fulfills the requirements of the industry standard EN 934-2 (February 2002).

[0277] In one preferred embodimenta -dicalcium silicate hydrate is used in a calcium silicate hydrate suspension comprising water and a water-soluble polymeric dispersant, to improve storage stability by reducing the viscosity increase.

[0278] In a preferred embodiment viscosity increase of the calcium silicate hydrate suspension comprising water, a water-soluble polymeric dispersant and a -dicalcium silicate hydrate is less than 1500 mPa*, preferably less than 1000 mPa*, most preferably less than 500 mPa* after storage of the composition for 60 days at 60° C, wherein the composition comprises 25 wt.-% calcium silicate hydrate.

[0279] In a further preferred embodiment, the calcium silicate hydrate composition according to the invention is used as curing accelerator for hydraulic or latent hydraulic binders.BASF SE 240796W001

[0280] 29

[0281] Preferably the hydraulic or latent hydraulic binders are in particular cement, slag, preferably granulated blast furnace slag, flyash, silica flour, metakaolin, natural pozzolanas, calcined oil shale, calcium sulfoaluminate cements and / or calcium aluminate cements, preferably the binders comprising predominantly cement as hydraulic binder.

[0282] The building material mixture can also comprise further additives which are typically used in the field of building chemicals, for example other curing accelerators, dispersants, plasticizers, water reducers, setting retarders, antifoams, air pore formers, retarders, shrinkage-reducing agents, redispersible powders, freezing protection agents and / or antiefflorescence agents.

[0283] Preferably the calcium silicate hydrate composition according to the invention is dosed at 0.01 to 10 wt.-%, most preferably at 0.1 to 2 wt.-% of the solids content with respect to the hydraulic binder, preferably cement. The solids content is determined in an oven at 60 ° C until a constant weight of the sample is reached.

[0284] The invention will be illustrated by the the following examples and figures.BASF SE 240796W001

[0285] 30

[0286] Examples

[0287] Measurement of calorimetric performance:

[0288] For the calorimetric test all working materials must be conditioned to room temperature (20-23 ° C). The test is performed in cement paste with a water / cement ration of 0.4.

[0289] Following steps are performed:

[0290] • Weighting in 50.00g (+ / - 0.05g) of cement (CEM I) into a sealable cup (laboratory scale).

[0291] • For reference sample: weighting in 0.75 g (+ / - 0.005 g) of HyCon S 7042 F powder (commercial CSH seed) with an analytical balance and add to the cup with cement. Then the cup is closed and homogenized by shaking by hand. Weight in 20 g water (w / c = 0.4).

[0292] • For the tested sample material: weighting in the CSH suspension (+ / - 0.01g) and then the water (+ / - 0.1 g). The water introduced from the CSH suspension has to be taken into account.

[0293] • Homogenization using an IKA stirrer motor (setting: 2000 rpm) for 90 s

[0294] • Fill 5-6 g of the cement paste containing the CSH seeds into the calorimetry ampoule with a pipette and screw the lid on tightly

[0295] • Finally, the ampule is placed into the calorimeter (TAM Air) and the measurement started (measurement at 20 ° C).

[0296] To determine the performance, the measured cumulative heat between 0.5 and 4 h of the C-S-H suspension to be tested is compared to the HyCon S 7042 F reference.

[0297] Measurement of viscosity:

[0298] The viscosity is determined by a Brookfield viscometer (type: EV). The sample is placed in a container and shaken for 15 s. The viscosity is measured with the appropriate spindle after 1 min at 12 rpm.

[0299] Spindle types:

[0300] • up to 250 mPas: spindle no. 61

[0301] • 250 - 2500 mPas: spindle no. 62

[0302] • from 2500 mPas: spindle no. 63

[0303] Estimation of particle size of the raw materials:

[0304] Determination of particle size distribution by light scattering using Beckman-Coulter LS 13320. Procedure:

[0305] Droping 10 - 13 drops of CSH suspension into sample vials with 7 ml of demineralized water for pre-dilution

[0306] Homogenization of the dilution without introducing air bubbles using a pipette Dispensing the diluted CS-Slurry dropwise into the measuring device using a pipette until the optimal measurement concentration is reached

[0307] Optimal measurement concentration PIDS 40 - 45%; ensure freedom from air bubbles! Refractive index used: 1.59BASF SE 240796W001

[0308] 31

[0309] X-ray diffraction analysis (XRD) and Rietveld analysis

[0310] The content of the crystalline phases and the amorphous phase was determined by X-ray diffraction (XRD). The samples (suspension or granulate) were dried before sample preparation (at 150 ° C) and ground in a micronizer mill. The measured diffraction patterns were evaluated using the Rietveld method. The amorphous content was evaluated using an internal standard (CaF2), allowing for the determination of the absolute content of each crystalline phase, including a -dicalcium silicate hydrate.

[0311] The XRDs were performed using a Bruker AXS D8 ENDEAVOR (CuKct radiation, 40 kV, 35 mA), and the Rietveld measurements were conducted using Bruker's Topas 6.0 software. For the XRD analysis, the hydrothermal calcium silicate hydrate from the autoclave process was crushed to a particle size with a d(95) value of < 1 mm using a jaw crusher and an impact mill. Subsequently, 5 g of the powder was dried at 105° C for 1 hour in a laboratory oven. For the XRD analysis, 3 g of the dried powder was ground in an agate mortar until the sample could pass through a sieve with a mesh size of 36 pm.

[0312] The sample for the determination of the amount of a -dicalcium silicate hydrate (a-C2SH) was a homogeneously mixed powder containing the sample and a known amount of an internal crystalline standard. The use of the internal standard is for determining the amorphous content. For these investigations, 15 wt.-% to 30 wt.-% fluorite (CaF2) was homogenously blended with the sample (particle size < 36 pm) in an agate mortar. Then, the homogenized powder, which contains fluorite as an internal standard, was prepared and measured using "front loading" technique. The prerequisite for using fluorite as an internal standard is that fluorite is not present in the original sample. A standard with a mass attenuation coefficient (MAC) that is similar to that of the sample should be chosen to minimize X-ray absorption contrast. The samples have a MAC value for Cu Ka radiation between 75 and 80 cm2 / g. Therefore, CaF2with a MAC value of 94.96 cm2 / g was chosen. According to the scientific literature, for the amount of internal standard, about 20 wt.-% is recommended for an amorphous content of the sample to be determined, ranging from 30 wt.-% to 90 wt.-% (Scrivener, Snellings, and Lothenbach. "Chapter 4. X-Ray Powder Diffraction Applied to Cement." A Practical Guide to Microstructural Analysis of Cementitious Materials. CRC / Taylor & Francis Group, 2016. 107-176). The examined samples contain 10 wt.-% to 98 wt.-% of X-ray amorphous or nanocrystalline phases with crystal sizes < 5 nm, so 15 wt.-% and 30 wt.-% of internal standard were used.

[0313] The X-ray diffraction patterns recorded by X-ray diffraction analysis (diffractograms) were subsequently analyzed using the Rietveld analysis with Topas 6.0 software. The Rietveld method is a standard procedure for analyzing diffractograms obtained by X-ray diffraction analysis of powder samples. The method is extensively described, for example, in G. Will (2006): Powder Diffraction - The Rietveld method and the two-stage method, Springer Verlag, and R. Young (1995): The Rietveld method, lUCr Monographs on Crystallography, vol. 5, Oxford University Press.

[0314] For the Rietveld analysis of the present samples, the following structural data were used according to the Inorganic Crystal Structure Database (ICSD):BASF SE 240796W001

[0315] 32

[0316] a -Dicalcium silicate hydrate (a -C2SH): ICSD number 73404

[0317] Tobermorite (mineral of calcium silicate hydrates): ICSD number 152489

[0318] Calcite: ICSD number 79674

[0319] Quartz: ICSD number 174

[0320] Portlandite: ICSD number 15471

[0321] Fluorite: ICSD number 60368

[0322] By means of Rietveld analysis, in addition to the phase content of individual phases, the crystal size of the calcium silicate hydrate phase tobermorite was determined. The crystal size is reflected in the full width at half maximum (FWHM) of the reflections of a phase and is determined during the refinement process of the Rietveld analysis. The relationship between FWHM of a reflection in the diffractogram and the crystal size is described, for example, in Chapter 5.4.1 from page 142 in R. Dinnebier, S. Billinge (2008): Powder Diffraction - Theory and Practice, RSC Publishing, as well as on page 113 in G. Will (2006): Powder Diffraction - The Rietveld method and the two-stage method, Springer Verlag, and R. Young (1995): The Rietveld method, lUCr Monographs on Crystallography, vol. 5, Oxford University Press.

[0323] The determination of the amorphous phase content using an internal standard is used to quantify the absolute amount of crystalline phases and amorphous phases and was performed according to the publication by I. Madsen, N. Scarlett, and A. Kern, "Description and survey of methodologies for the determination of amorphous content via X-ray powder diffraction." Zeitschrift fur Krista I logra ph ie Crystalline Materials, Band 226, Heft 12 (2011): 944-955. During the Rietveld refinement, the known amount of the internal standard is given and the other phases are related to it. The difference between the sum of crystalline phases ( a -C2SH, tobermorite, calcite, quartz, portlandite, fluorite) and 100 wt.-% corresponds to the amorphous content of the sample.

[0324] Fig. 1 shows X-ray diffraction spectra of samples of semi-ordered calcium silicate hydrate (i) without a -dicalcium silicate hydrate (a-C2SH) ("htCSH3" according to citation WQ2018154012, page 39, line 36ff), (ii) with a low content of a -C2SH (C2SH_1), and (iii) with a high content of a -C2SH (C2SH_2).

[0325] The distinguishable peaks or maxima with the highest intensities were assigned to the phases. The abbreviations for the phases are:

[0326] * - a -dicalcium silicate hydrate (a-C2SH)

[0327] P - Portlandite

[0328] Cc - Calcite

[0329] Qz - alpha-quartz

[0330] T - Tobermorite 14 A

[0331] sCSH - semi-ordered calcium silicate hydrate

[0332] Unlabeled peaks are assigned to various phases from the listed phase list.BASF SE 240796W001

[0333] 33

[0334] As can be seen in fig. 1 (sample C2SH_2), the measured a -dicalcium silicate hydrate shows a well-resolved spectrum with sharp peaks. Even in a sample of semi-ordered calcium silicate hydrates with a low proportion of a -dicalcium silicate hydrate (C2SH_1), a -dicalcium silicate hydrate is easy to identify. The peaks at 16.6° 26 , 27.2° 26 , and 37.1° 26 , indicated in the figure, are crucial for the identification of a -dicalcium silicate hydrate using the Cu-K a radiation (corresponding to the crystal planes of a -dicalcium silicate hydrate with the Miller indices (0 0 2), (1 2 2), and (2 2 3)).

[0335] Figure 1: XRD spectrum of htCSH containing no a -dicalcium silicate hydrate (htCSH3), low amounts (4.3 wt.-%) of a -dicalcium silicate hydrate (C2SH_1) and high amounts (45 wt.-%) of a -dicalcium silicate hydrate (C2SH_2).

[0336] Due to the good crystallinity of a -dicalcium silicate hydrate, the limit of determination is at 0.2 wt.-% using XRD evaluation with the Rietveld method. An illustrative example for this is shown in figure 2.

[0337] Figure 2: The main peak of a -dicalcium silicate hydrate at 27.2 ° 2 Th (using Copper K alpha radiation with a wavelength of 1.5406 A) is still visible in a CSH sample containing 0.2 wt.-% of a -dicalcium silicate (“C2SH_3”), compared to a sample without a -dicalcium silicate (“htCSH3”).

[0338] Example 1

[0339] Method 1:

[0340] Preparation of hydrothermal calcium silicate hydrate comprising a -dicalciumsilicate hydrate

[0341] htCSHa and htCSHb:

[0342] 185 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm), 70 kg lime milk (14 kg calcium oxide slaked with 56 kg water) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 410 kg water under constant stirring. Depending on the targeted a -C2SH content (e.g. > 30 wt.-% - htCSHb) small amounts of a -C2SH seeds can be added at this step to the composition to promote a -C2SH formation. The suspension was poured into a form and demolded after getting puncture resistant. The hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block was granulated by a crusher and finely ground as a suspension with 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI by a bead mill up to a fineness of < 3 pm. The suspension was diluted to a solid content of 30 wt.-%. The phase analysis and the amount of a -dicalcium silicate hydrate in the hydrothermal calcium silicate hydrate granulate was determined after the granulation step prior to the wet milling via XRD.BASF SE 240796W001

[0343] 34

[0344] htCSHa_l:

[0345] 180 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm), 100 kg lime milk (20 kg calcium oxide slaked with 80 kg water) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 386 kg water under constant stirring. The suspension was poured into a form and demolded after getting puncture resistant. The hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block was granulated by a crusher and finely ground as a suspension with 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI by a bead mill up to a fineness of < 3 pm. The suspension was diluted to a solid content of 30 wt.-%. The phase analysis and the amount of a -dicalcium silicate hydrate in the hydrothermal calcium silicate hydrate granulate was determined after the granulation step prior to the wet milling via XRD.

[0346] htCSHa_2:

[0347] 156 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm), 219 kg lime milk (43.8 kg calcium oxide slaked with 175.2 kg water) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 291 kg water under constant stirring. The suspension was poured into a form and demolded after getting puncture resistant. The hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block was granulated by a crusher and finely ground as a suspension with 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI by a bead mill up to a fineness of < 3 pm. The suspension was diluted to a solid content of 30 wt.-%. The phase analysis and the amount of a -dicalcium silicate hydrate in the hydrothermal calcium silicate hydrate granulate was determined after the granulation step prior to the wet milling via XRD.

[0348] htCSHa_3 (only lime milk):

[0349] 69 g quartz powder (d95 < 63 pm) were added to 424 g lime milk (137 g calcium oxide slaked with 287 g water) under constant stirring. The suspension was poured into a flask and placed into a pressure cell (500 mL), which contains 30 g water on the bottom. The cell was placed into an oven. The cell was open and demolded after the C-S-H got puncture resistant. The hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block was granulated crushed and finely ground. The phase analysis and the amount of a -dicalcium silicate hydrate in the hydrothermal calcium silicate hydrate granulate was determined after the granulation step prior to the wet milling via XRD.BASF SE 240796W001

[0350] Table 1: Composition of htCSH synthesized in example 1, method 1.

[0351]

[0352] Synthesis of dispersant DI:

[0353] In a 1-liter four-necked flask with a thermometer, a reflux cooler, and a connection for two inlets, 875 g of a 40% aqueous solution of polyethylene glycol hydroxybutyl monovinyl ether is introduced. Details regarding the molar masses of the respective polyethylene glycol hydroxybutyl monovinyl ether can be found in Table 2. The solution is then cooled to 20 'C. Acrylic acid (99%) is slowly added to the polyethylene glycol hydroxybutyl monovinyl ether solution in the flask. The pH value decreases to about 4-5. Afterward, 0.5 g of iron (ll)sulfate heptahydrate, as well as 5 g of Rongalit and mercaptoethanol, are added. After brief stirring, 3 g of 50% hydrogen peroxide are also added. The temperature increases from 20 ° C to about 30 ° C to 65 ° C. The solution is then stirred for 10 minutes before it is neutralized with caustic soda (20%). A slightly yellow-colored, clear aqueous polymer solution with a solid content of about 40% by weight is obtained. The quantities of the chemicals used (mercaptoethanol, and acrylic acid) and the molar masses of the respective polyethylene glycol hydroxybutyl monovinyl ethers (PEG-HBVE), weight average molar mass, and the charge density of the polymer (number of moles of carboxylate and / or carboxyl groups / total molar mass of the PCEs) (mol / (g / mol)) can be found in the Table 2.

[0354] Table 2: Chemical properties of the polymer used for the CSH accelerator suspensions

[0355]

[0356] BASF SE 240796W001

[0357] Method 2:

[0358] Addition of a -dicalciumsilicate hydrate as a solid phase to hydrothermal calcium silicate hydrate (solid-solid mixture).

[0359] 200 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 410 kg water under constant stirring. The suspension was poured into a form and demolded after getting puncture resistant. The hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block was granulated by a crusher.

[0360] Table 3: Composition of htCSH synthesized in example 1, method 2.

[0361]

[0362] 94.5 parts of the received product htCSHc was mixed with 4.5 parts of a granulated material containing a -C2SH according to htCSHb (example 1, method 1). The mixture was homogenized. The homogenized mixture, water and dispersant DI were mixed and finely ground as a suspension by a bead mill up to a fineness of < 3 pm, wherein the composition comprised 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI. The final suspension was diluted to a solid content of 30 wt.-%. The a -dicalcium silicate hydrate content was 2.0 wt.-% based on the dry weight of the composition.

[0363] Method 3:

[0364] Addition of a -dicalcium silicate hydrate suspension to a hydrothermal calcium silicate hydrate suspension.

[0365] 200 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 410 kg water under constant stirring. The suspension was poured into a form and demolded after getting puncture resistant. Hydrothermal reaction was proceeded at 170 ° C (about 8 bar) for 12 h.BASF SE 240796W001

[0366] 37

[0367] The resulting calcium silicate hydrate-block (corresponding to htCSHc) was granulated by a crusher and finely ground as a suspension with 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI by a bead mill up to a fineness of < 3 pm. The suspension was diluted to a solid content of 30 wt.-%. The phase analysis of the granulate was determined after the granulation step prior to the wet milling via XRD.

[0368] 95.5 parts of the received product from the granulate htCSHc was mixed with 4.5 parts of a suspension containing a -C2SH according to htCSHb.

[0369] The mixture of the two suspensions was homogenized for 5 min using a magnetic stirrer. The final suspension has a solid content of 30 wt.-% and the a -dicalcium silicate hydrate content was 2.0 wt.-% based on the dry weight of the composition.

[0370] Method 4:

[0371] Addition of a -dicalcium silicate hydrate suspension to an aged hydrothermal calcium silicate hydrate suspension.

[0372] 200 kg calcium oxide (d95 < 90 pm), 100 kg quartz powder (d95 < 63 pm) and 222 g aluminum paste (solid content 60 %, d50 = 15 pm) were added to 410 kg water under constant stirring. The suspension was poured into a form and demolded after getting puncture resistant. Hydrothermal hardening was proceeded at 170 ° C (about 8 bar) for 12 h. The resulting calcium silicate hydrate-block (corresponding to htCSHc) was granulated by a crusher and finely ground as a suspension with 30 wt.-% calcium silicate hydrate and 6.4 wt.-% dispersant DI by a bead mill up to a fineness of < 3 pm. The suspension was diluted to a solid content of 30 wt.-%. The phase analysis of the granulate was determined after the granulation step prior to the wet milling via XRD.

[0373] The suspension was placed into an oven at 60° C for 28 days.

[0374] 82.3 parts of the received product was mixed with 17.8 parts of a suspension containing a -C2SH according to htCSHb.

[0375] The mixture of the two suspensions was homogenized for 5 min using a magnetic stirrer. The final suspension has a solid content of 30 wt.-% and the a -dicalcium silicate hydrate content was 8.1 wt.-% based on the dry weight of the composition.BASF SE 240796W001

[0376] 38

[0377] Table 4: Viscosity development of htCSH suspensions with and without a -dicalcium silicate hydrate as introduced by Method 1-4. The storage temperature was 60 ° C.

[0378]

[0379] REF: The reference sample of calcium silicate hydrate was prepared according to Method 3 without adding a suspension containing a -dicalcium silicate hydrate.

[0380] All samples in Table 4 were stored at 60° C.

[0381] The reference sample (REF) in Table 4 shows the typical increase of viscosity of a calcium silicate hydrate suspension over time. All methods 1 to 4 according to the invention lead to a significantly reduced increase in viscosity over time or even reduce the viscosity, as shown with Method 4.

[0382] Example 2

[0383] Samples EX 2.1 to EX 2.5 were prepared according to example 1, Method 3. In EX 2.1 the suspension containing a -dicalcium silicate hydrate was not added. In EX 2.2 to EX 2.5, the suspension containing a -dicalcium silicate hydrate was added in an amount such that the dry weight of the composition reached the amount of a -dicalcium silicate hydrate given in table 5. The samples were stored at 60 ° C and the viscosity was measured by a Brookfield viscometer.BASF SE 240796W001

[0384] 39

[0385] Table 5: Development of viscosities of htCSH suspensions as function of a -dicalcium silicate hydrate content. The storage temperature was 60 ° C.

[0386]

[0387] Table 5 shows the relation between the added amount of a -C2SH and the development of viscosity over time at 60 ° C storage.

[0388] Example 3

[0389] Calcium silicate hydrate:

[0390] The calcium silicate hydrate suspension was synthesized according to WO 2010 / 026155, page 40, example “Acc. 5” in table 2.

[0391] Calcium silicate hydrate containing a -dicalcium silicate hydrate:

[0392] Calcium silicate hydrate comprising -dicalcium silicate hydrate was synthesized according to example 1, method 1 using htCSHb.

[0393] The suspension of calcium silicate hydrate htCSHb containing a -dicalcium silicate hydrate, prepared according to the procedure described in example 1, method 1, was dosed to the calcium silicate hydrate suspension according to WO 2010 / 026155 in an amount such that the dry weight of the composition reached the amount of a -dicalcium silicate hydrate given in Table 6 and Table 7. In table 6 the calcium silicate hydrate suspension according to WO 2010 / 026155 was aged for 120 days at 20 ° C before the suspension of calcium silicate hydrate containing -dicalcium silicate hydrate was added. In table 7 the calcium silicate hydrate suspension according to WO 2010 / 026155 was prepared and the suspension of calcium silicate hydrate containinga -dicalcium silicate hydrate was immediately added. The samples in table 6 and 7 were stored at 60 ° C and the viscosity was measured by a Brookfield viscometer.

[0394] Table 6: Development of viscosities of CSH suspensions, prepared according to WO 2010 / 026155, page 40, example “Acc. 5” in table 2, and the subsequent addition of a -BASF SE 240796W001

[0395] 40

[0396] dicalcium silicate hydrate containing htCSH-suspension. The storage temperature was 60 ° C

[0397]

[0398] Table 6 shows the relation between the added amount of a -C2SH and the development of viscosity over time at 60 ° C storage.

[0399] Table 7: Development of viscosities of fresh CSH suspensions, prepared according to WO 2010 / 026155, page 40, example “Acc. 5” in table 2, and the subsequent addition of a -dicalcium silicate hydrate containing htCSH-suspension. The storage temperature was 60 ° C.

[0400]

[0401] BASF SE 240796W001

[0402] 41

[0403] Table 7 shows the relation between the added amount of a -dicalcium silicate hydrate and the development of viscosity over time at 60 ° C storage.

[0404] Example 4

[0405] The calcium silicate hydrate suspension was synthesized according to WO 2010 / 026155, page 40, example “Acc. 5” in table 2, with the exception of adding a a -dicalcium silicate hydrate containing suspension to Solution 3 before the subsequent addition of Solution 1 and Solution 2. The a -dicalcium silicate hydrate was synthesized according to example 1, method 1 using htCSHb. The suspension containing a -dicalcium silicate hydrate was added in an amount such that the dry weight of the final composition reached the amount of a -dicalcium silicate hydrate given in Table 8.

[0406] Table 8: Development of viscosities of fresh CSH suspensions, prepared according to WO 2010 / 026155, page 40, example “Acc. 5” in table 2, with and without addition of a-C2SH containing htCSH-suspension to solution 3. The storage temperature was 23° C.

[0407]

[0408] Table 8 shows, that the presence of a -C2SH according to invention leads to a significantly reduced increase in viscosity over time. The effect of a -C2SH on the acceleration performance is negligible.

Claims

BASF SE 240796W00142Claims1. Calcium silicate hydrate composition comprising water and a water-soluble polymeric dispersant, wherein the ratio of calcium silicate hydrate to the water-soluble polymeric dispersant is 15:1 to 1:3, characterized in that the composition comprises 0.3 to 25 wt.- % of a -dicalcium silicate hydrate, measured by XRD evaluation with the Rietveld method, based on the dry weight of the composition.

2. Calcium silicate hydrate composition according to claim 1, wherein the composition comprises 24 - 93 wt.-% of calcium silicate hydrate based on the dry weight of the composition.

3. Calcium silicate hydrate composition according to claims 1 or 2, wherein the composition comprises between 24 to 99 wt.-% of water.

4. Calcium silicate hydrate composition according to any of claims 1 to 3, wherein the composition consists of particles with a d(50) particle size of < 800 nm, determined by static light scattering according to ISO 13320:2020.

5. Calcium silicate hydrate composition according to any of claims 1 to 4, wherein the water-soluble polymeric dispersant has polyether side chains represented by the structural unit (I),*-U-(C(O))k-X-(AlkO)n-W (I)where* indicates the bonding site to the polymer,U is a chemical bond or an alkylene group having 1 to 8 carbon atoms,X is oxygen, sulfur or a group NR1,k is 0 or 1,n is an integer whose average value based on the polymer is in the range from 3 to 300,Aik is C2-C4alkylene, it being possible for Aik to be identical or different within the group (Alk-O)n,W is a hydrogen, a Cx-C6alkyl or an aryl radical or is the group Y-F, whereY is a linear or branched alkylene group having 2 to 8 carbon atoms and may carry a phenyl ring,F is a 5- to 10-membered nitrogen heterocycle which is bonded via nitrogen and which as ring members, besides the nitrogen atom and besides carbon atoms,BASF SE 240796W00143may have 1, 2 or 3 additional heteroatoms, selected from oxygen, nitrogen, and sulfur, it being possible for the nitrogen ring members to have a group R2, and for 1 or 2 carbon ring members to be present in the form of a carbonyl group, R1is hydrogen, Cj-C4alkyl or benzyl, andR2is hydrogen, Cj-C4alkyl or benzyl.

6. Calcium silicate hydrate composition according to any of claims 1 to 5, wherein the water-soluble polymeric dispersant is a polycondensation product comprising(II) a structural unit comprising an aromatic or heteroaromatic group and the polyether group, and(III) a phosphated structural unit comprising an aromatic or heteroaromatic group.

7. Use of calcium silicate hydrate composition according to claim 1 or 6, as curing accelerator for hydraulic or latent hydraulic binders.

8. A process for producing a composition comprising calcium silicate hydrate according to claims 1 to 6, whereina) an aqueous solution or suspension of a calcium source is reacted with an aqueous solution or suspension of a silicate source and whereinb) the reaction of step a) is made in the presence of at least one water-soluble polymeric dispersant or the at least one water-soluble polymeric dispersant is added after step a) and whereinc) a composition comprising a -dicalcium silicate hydrate is introduced before the start of the reaction in step a) or is added during or after step a).

9. A process according to claim 8, characterized in that the composition comprising a - dicalcium silicate hydrate is added before step a).

10. A process for producing a composition comprising calcium silicate hydrate according to claims 1 to 6, wherein calcium silicate hydrate is brought into contact with at least one water-soluble polymeric dispersant in an aqueous medium by introducing kinetic energy, wherein the calcium silicate hydrate comprisinga -dicalcium silicate hydrate has been produced by reacting calcium oxide with silicon dioxide, wherein the molar ratio of Ca / Si in the range from 0.5 to 2.5, in the presence of water under hydrothermal conditions at a temperature in the range from 100° C to 300° C for a period of from 1 hours to 30 hours, wherein from 1 to 90 wt.-% of the total CaO is slaked with water in a separate reaction to form calcium hydroxide and introduced into the reaction mixture prior to the hydrothermal reaction.

11. A process according to claim 10, wherein the kinetic energy is effected by introduction of mixing or shearing energy.BASF SE 240796W0014412. A process according to claim 10, wherein the kinetic energy is effected by milling.

13. A process according to any of claims 9 to 11, wherein the kinetic energy is introduced until the mineral constituent has a d(50) particle size of < 800 nm determined by static light scattering according to ISO 13320:2020.

14. A process according to any of claims 9 to 12, wherein the reaction of calcium oxide or calcium hydroxide with silicon dioxide in the presence of water under hydrothermal conditions is made in the presence of a foaming agent.

15. Use of a -dicalcium silicate hydrate in a calcium silicate hydrate suspension comprising water and a water-soluble polymeric dispersant, to improve storage stability by reducing the viscosity increase.

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