Free-flowing powder comprising a porous substrate functionalized with at least one accelerator

Abstract

The present invention relates to a free-flowing powder composition comprising at least one substrate, said substrate having pores and an outer surface between said pores, wherein said outer surface is functionalized with at least one accelerator for a hydraulic setting composition, said accelerator being liquid, or hygroscopic or deliquescent, and wherein at least 80 wt.% of said accelerator dissolves after immersion of said free-flowing powder composition in water at 20°C for 15 minutes, provided that said free-flowing powder composition is immersed in water in an amount sufficient to make it impossible to reach a saturated concentration of said accelerator. The present invention also relates to a process for the preparation of said free-flowing powder composition. The present invention also relates to the use of said free-flowing powder composition as an additive for a mortar or concrete composition to provide an accelerating effect, an anti-aging effect and an anti-dusting effect. The present invention also relates to a dry mortar or concrete composition comprising a hydraulic binder, said free-flowing powder composition and particles, a wet mortar or concrete composition and a hardened body obtained therefrom.

Description

Technical Field

[0001] This invention relates to the field of industrial mortar and concrete. In particular, this invention relates to an accelerator for mortar or concrete that includes a hydraulic binder.

[0002] More specifically, the present invention relates to a free-flowing powder comprising a porous substrate functionalized with at least one promoter. Background Technology

[0003] Cement-based dry mortar and concrete mixes typically require accelerators to ensure rapid setting and / or rapid development of strength and performance after they have been mixed with water and installed.

[0004] These accelerators are also used to partially compensate for the loss of reactivity in cement-based binders during storage due to exposure to air moisture or interaction with other components of the dry mix, a process commonly referred to as "aging".

[0005] In summary, the three main effects of accelerators are: accelerating solidification, increasing the kinetics of performance development, and compensating for aging effects.

[0006] Among commonly used accelerators, some are hygroscopic or deliquescent, or are available only in liquid form, such as alkanolamines (MEA, DEA, TEA, MDEA, TIPA).

[0007] Case of liquid accelerator:

[0008] Throughout this invention, unless otherwise stated, the term "liquid" means that the corresponding substance described as a liquid is in a liquid physical state at 20°C and 10¹³ mbar. Similarly, the term "solid" means that the corresponding substance described as a solid is in a solid physical state at 20°C and 10¹³ mbar.

[0009] For example, alkanolamines are commonly used as abrasives and are known to have a promoting effect, but they have several drawbacks that severely limit their practical application in dry mortar or concrete mixes.

[0010] In reality, alkanolamines are fluid liquids, very viscous liquids, or solids at typical dry mortar or concrete composition temperatures (5–35°C) due to their low melting points (below 30°C for DEA and 60°C for TIPA). Adding liquids during dry mixing can be difficult because their presence can lead to clumping. Furthermore, aqueous liquids cause hydration reactions with the cementitious binder particles surrounding the droplets, which can contribute to aging of the dry mortar or concrete composition. Additionally, the industrial handling and metering of these additives are highly complex because the viscosity of these liquids can vary considerably across the manufacturing temperature range, or even undergo a liquid / solid transition.

[0011] Therefore, it would be advantageous to provide a free-flowing powder containing a liquid accelerator, which would allow the liquid accelerator to be added to dry mortar or concrete compositions without causing disadvantages such as clumping, aging, or difficulty in handling, metering, and mixing.

[0012] Therefore, it would be beneficial to provide a free-flowing powder containing an accelerator that undergoes a liquid / solid transition at normal temperatures, so that the liquid / solid transition does not cause disadvantages such as agglomeration, aging, or difficulties in industrial processing, metering, and mixing.

[0013] Case of hygroscopic or deliquescent accelerators

[0014] For example, calcium chloride (CaCl2) is often used as an accelerator in cement-based mortar or concrete, but it has some drawbacks that severely limit its practical application.

[0015] Indeed, calcium chloride is a highly hygroscopic compound, which makes its industrial applications, especially its handling, difficult because it clumps very quickly. Therefore, metering its feeding is difficult, and in some cases even impossible. Furthermore, CaCl2 causes excessive and rapid corrosion of industrial tools. Most importantly, the highly hygroscopic behavior of CaCl2 makes its free-flowing powder form virtually nonexistent, as it rapidly transforms into a saturated liquid solution of CaCl2, also known as brine; therefore, free CaCl2 cannot be used in dry-mixed compositions.

[0016] Even where specific production organizations can be established to allow the industrial use of dry-mixed CaCl2 as a accelerator in the dry-mix mortar and concrete sector, its highly hygroscopic behavior results in faster and more dangerous aging of the dry-mixes under consideration. This faster and more dangerous aging is due to the localized formation of brine near the hygroscopic CaCl2 particles within the dry-mix. These droplets of saturated CaCl2 solution induce agglomeration in the dry-mix, reacting with the cementitious binder particles surrounding the CaCl2. As a result, after a period of time, the dry-mix mortar or concrete partially or completely loses its practical use due to aging into a hardened product and ceases to be a reactive mixture.

[0017] The amount of CaCl2 that can be added is limited because the formation of brine leads to the release of chlorides into the mortar or concrete, and due to the corrosive effects of chlorides, care must be taken not to exceed the chloride content limits specified in some national or international standards. Therefore, the maximum permissible amount of CaCl2 obtained is usually insufficient to achieve the desired promoting effect.

[0018] Therefore, calcium chloride can hardly be used in dry-mix mortar and concrete, and its use is usually limited to liquid (salt water) addition during on-site wet-mixing of dry-mixing agents.

[0019] Some efforts have been made to overcome these drawbacks. For example, US Patent 1,791,630 discloses a method and means for preserving calcium chloride under dry conditions when exposed to air. The proposed solution is to combine hygroscopic salts with non-hygroscopic powder materials. This combination is achieved by grinding the hygroscopic salts and non-hygroscopic materials together in a rotary hammer mill or equivalent. As a result, according to the authors, each hygroscopic salt is surrounded by finely powdered non-hygroscopic material, thereby preventing the hygroscopic salts from absorbing moisture.

[0020] The contents of Chinese patent applications CN106348643, CN110104988, and CN109250964 regarding methods for providing calcium chloride-modified diatomite may also be cited. These methods include a wet mixing process that causes calcium chloride to permeate into the pores of the diatomite.

[0021] Although these compositions allow for the treatment of hygroscopic salts in a dry state, the effect of hygroscopic salts in mortar compositions is negatively impacted. In fact, the hygroscopic salts are trapped in non-hygroscopic materials and are therefore less usable in wet mortar compositions because the release of the hygroscopic salts is slowed down.

[0022] Therefore, it would be beneficial to provide a free-flowing powder containing a liquid, hygroscopic or deliquescent accelerator that does not delay the release of the accelerator in a wet mortar or concrete composition.

[0023] Advantages of this invention over the prior art

[0024] One advantage of this invention is that it provides a dry powder form of a hygroscopic or deliquescent liquid accelerator, which is a ready-to-use dry mix formulation that can be processed without air prevention measures. In other words, the accelerator of this invention avoids the problems caused by the liquid form or hygroscopic or deliquescent behavior of prior art accelerators, and in particular, the accelerator of this invention allows for the preparation of ready-to-use dry mix formulations.

[0025] Another advantage of this invention is that it accelerates the hardening of the final mortar or concrete, which is one of the original purposes of introducing the accelerator.

[0026] Another advantage is the surprising reduction in aging of prepared dry mortar and concrete intended for storage before use. In effect, the hygroscopic additive, which traps moisture from the air, can induce the formation of a liquid in its vicinity. This liquid (a solution of the compound in water) can react with the cement, thereby hydrating and aging it, i.e., reducing its overall reactivity. This is visible, for example, by the formation of dark spots that highlight the presence of the liquid and localized hydration of the cement. Throughout the invention, this behavior is also referred to as the "anti-aging effect."

[0027] An additional advantage of this invention is that it eliminates the need for excessively metered accelerators. Instead, this invention surprisingly allows for a reduction in the amount of hygroscopic salt accelerator required to achieve the desired accelerating effect.

[0028] Furthermore, the present invention surprisingly has the advantage of reducing dust generated when processing ready-to-use prepared mortar or dry concrete mixtures. This allows for safer use because it reduces contact between potentially irritating dust (e.g., cement microparticles) and skin or mucus, and reduces the inhalation levels of potentially hazardous inhalable microparticles (e.g., crystalline silica). Invention Overview

[0030] The present invention relates to a free-flowing powder composition comprising at least one substrate having pores and an outer surface between the pores, wherein the outer surface is functionalized with at least one accelerator for a hydraulically curing composition, the accelerator being liquid, hygroscopic, or deliquescent, and wherein at least 80% by weight of the accelerator dissolves after immersing the free-flowing powder composition in water at 20°C for 15 minutes, provided that the free-flowing powder composition is immersed in an amount of water sufficient to make it impossible to reach a saturation concentration of the accelerator.

[0031] The present invention also relates to a method for preparing the free-flowing powder composition.

[0032] The present invention also relates to the use of the free-flowing powder composition as an additive to mortar or concrete compositions to provide promoting effects, anti-aging effects and anti-dust effects.

[0033] The present invention also relates to a dry mortar or concrete composition comprising a hydraulic binder, the free-flowing powder composition and particles, a wet mortar or concrete composition obtained therefrom, and a hardened body.

[0034] Brief description of the attached figures

[0035] Other features, details, and advantages are shown in the following detailed description and accompanying drawings, in which:

[0036] Figure 1 It is a cross-sectional view of a substrate with pores and an outer surface.

[0037] Figure 2 This is a graph comparing the chloride concentration versus time in existing technologies and the present invention.

[0038] Figure 3 This is a graph comparing temperature versus time with existing technologies and the present invention.

[0039] Figure 4 and 5 These are comparative photographs of the compositions of this invention and those of prior art.

[0040] Figure 6 This is a graph comparing the ultrasonic propagation speed of the prior art and the present invention against time. Invention Details

[0042] As described above, the present invention relates to a free-flowing powder composition comprising at least one substrate having pores and an outer surface between the pores, wherein the outer surface is functionalized with at least one accelerator for a hydraulically curing composition, the accelerator being liquid, hygroscopic, or deliquescent, and wherein at least 80% by weight of the accelerator dissolves after the free-flowing powder composition is immersed in water at 20°C for 15 minutes, provided that the free-flowing powder composition is immersed in an amount of water sufficient to make it impossible to reach the saturation concentration of the accelerator.

[0043] Unbound by any theory, it is believed that liquid, hygroscopic, or deliquescent accelerators absorb moisture trapped in the pores of porous substrates through capillary action.

[0044] definition

[0045] In the context of this invention, free-flowing powder refers to a solid in powder form that is sufficiently dry to be free of any agglomerates or agglomerates, or contains a small amount of such agglomerates or agglomerates so that it can be used industrially for metering and incorporating into dry blends without the use of specialized agglomeration breakup equipment. In other words, in the context of this invention, free-flowing powder refers to powder that may contain agglomerates or agglomerates that would disintegrate in a standard mixing process such as Sofraden's Ribbon mixer.

[0046] In the context of this invention, functionalization with at least one accelerator means that the accelerator is adsorbed onto the substrate in such a way that, in a dry composition, the accelerator essentially remains on the surface of the substrate. In fact, one object of this invention is to provide a free-flowing powder composition of a liquid, hygroscopic, or deliquescent accelerator, but in a manner that allows the accelerator to function in the formulation, particularly in wet mortar or concrete compositions. In other words, the liquid, hygroscopic, or deliquescent accelerator needs to be sufficiently bonded to the substrate so that the free-flowing composition of this invention can be processed without separating the liquid, hygroscopic, or deliquescent accelerator from the substrate, but will be released in wet compositions where the liquid, hygroscopic, or deliquescent accelerator is the active ingredient.

[0047] The term "accelerator" specifically refers to an additive used in mineral binder compositions that, compared to a reference composition without any such additive, shortens the time required to reach a given level of compressive strength and / or flexural strength after water is added to the mineral binder composition. In particular, within the context of this invention, the compressive strength and / or flexural strength of a mineral binder composition with added accelerator increase from 1 minute to 24 hours after mixing with water, compared to a reference composition without added accelerator.

[0048] The free-flowing powder composition of the present invention comprises a substrate having pores 1 and an outer surface 2. This substrate also defines an outer peripheral surface 3, which is the apparent surface of the substrate if the substrate has no pores. (Refer to...) Figure 1 The dashed line represents the portion of the outer peripheral surface 3 covering the pore 1, and the outer surface 2, marked with a thick line, corresponds to the outer peripheral surface 3 minus the portion of the outer peripheral surface 3 covering the pore 1. In other words, considering that the pore is a cavity with an open end located on the peripheral surface, the outer surface corresponds to the surface of the substrate between the pores.

[0049] In the context of this invention, "not reaching saturation concentration" means that the concentration of the accelerator after dissolving in water is less than its saturation concentration in water. Saturation concentration is the maximum possible amount of a substance that can dissolve in a standard volume of a specific solvent (e.g., water) under standard temperature and pressure conditions. In other words, "not reaching saturation concentration" means that there is enough water so that after immersing the free-flowing powder composition in water at 20°C and atmospheric pressure for 15 minutes, additional accelerator can still be dissolved in the water at 20°C and atmospheric pressure. Water as used herein refers to distilled water.

[0050] substrate

[0051] The substrate suitable for carrying out the present invention is any porous substrate on which liquids, particularly liquid water, can be absorbed and retained.

[0052] Advantageously, the substrate is a powder composed of porous particles having a diameter of at least 10 μm, preferably at least 15 μm, and more preferably between 20 μm and 100 μm. 50 diameter.

[0053] Particle size can be determined by laser diffraction as described in ISO 13320:2009. Specifically, a Mastersizer 2000 instrument with a Hydro 2000G dispersion unit and Mastersizer 2000 software from Malvern Instruments GmbH (Germany) can be used. 50 The value indicates that 50% of the particles have a smaller particle size and 50% have a larger particle size.

[0054] Advantageously, the substrate has a pore volume, as measured by mercury porosimetry, that accounts for at least 30%, preferably at least 40%, and more preferably at least 50% of the total apparent volume of the substrate. The total apparent volume corresponds to the sum of the pore volume and the volume of the substrate. In other words, the total apparent volume is equal to the volume occupied by the substrate if it were without pores. Mercury porosimetry can be performed according to ASTM D4404-18.

[0055] Advantageously, the substrate has an average pore size of less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm, which is measured by mercury porosimetry.

[0056] According to one embodiment, the substrate is a powder composed of porous particles, said porous particles having a diameter at least 10 μm, preferably at least 15 μm, more preferably 20 μm to 100 μm. 50 The diameter, and the average diameter of the hole is less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm.

[0057] According to another embodiment, the substrate is a powder composed of porous particles having a d50 diameter of at least 10 μm, preferably at least 15 μm, more preferably 20 μm to 100 μm, and the pore volume accounts for at least 30%, preferably at least 40%, more preferably at least 50% of the total apparent volume of the substrate, and the average diameter of the pores is less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm.

[0058] Therefore, one example is a powder composed of porous particles, wherein the d of the porous particles 50 The diameter is 20-100μm, and the average diameter of the pore is less than 10μm.

[0059] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50The diameter ranges from 20 to 100 μm, with an average pore diameter of less than 8 μm.

[0060] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50 The diameter is at least 10 μm and the average diameter of the pores is less than 5 μm.

[0061] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50 The diameter is at least 15 μm and the average diameter of the pores is less than 8 μm.

[0062] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50 The diameter is at least 10 μm, and the pore volume accounts for at least 40% of the total apparent volume of the substrate, and the average diameter of the pore is less than 8 μm.

[0063] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50 The diameter is at least 10 μm, and the pore volume accounts for at least 50% of the total apparent volume of the substrate, and the average diameter of the pore is less than 5 μm.

[0064] Therefore, another example is a substrate that is a powder composed of porous particles, the d of which 50 The diameter is 20μm-100μm, and the pore volume accounts for at least 30% of the total apparent volume of the substrate, and the average diameter of the pore is less than 10μm.

[0065] Therefore, the substrate is preferably selected from calcined clay, flaky vermiculite, zeolite, expanded perlite, precipitated silica, ground calcium carbonate, precipitated calcium carbonate, diatomaceous earth, calcined diatomaceous earth, and pulverized cementitious foam.

[0066] The calcined clay used as a substrate is preferably a porous calcined clay. Particularly preferred is that if the calcined clay is used as a substrate, the calcined clay is an expanded calcined clay.

[0067] In a particularly preferred embodiment, the substrate is diatomaceous earth.

[0068] Accelerator

[0069] According to the present invention, the accelerator may be liquid, hygroscopic or deliquescent.

[0070] In the context of this invention, a liquid accelerator refers to an accelerator that is liquid at room temperature, i.e., at a temperature between 5°C and 35°C. More specifically, in one embodiment of the free-flowing powder composition according to the invention, the accelerator is liquid and has a viscosity of less than or equal to 3000 Pa·s at 20°C and 1.013 bar.

[0071] More specifically, in another embodiment of the free-flowing powder composition of the present invention, the accelerator is a liquid and has a viscosity greater than or equal to 1.5 mPa·s at 20°C and 1.013 bar.

[0072] In the context of this invention, a moisture-absorbing accelerator refers to any accelerator that has moisture-absorbing behavior, that is, it can capture moisture from the air by adsorption.

[0073] In the context of this invention, a deliquescence accelerator refers to any accelerator that has deliquescent behavior, i.e., it can absorb moisture from the air until it forms a solution.

[0074] Therefore, in a preferred embodiment, the hygroscopic or deliquescent accelerator of the liquid is selected from the alkali metal or alkaline earth metal salts of any one of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium hydroxide, lithium sulfate, lithium carbonate, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, alkali metal nitrates, alkali metal nitrites, alkali metal thiocyanates, citric acid, formic acid, malonic acid, acetic acid, propionic acid, malic acid, or succinic acid, especially their sodium, potassium, or calcium salts, alkali metal silicates, alkanolamines, especially dimethylaminoethanol, diethylaminoethanol, N-methyldiethanolamine (MDEA), triethanolamine (TEA), triisopropanolamine (TIPA), diethanol-isopropanolamine (DEIPA), ethanol-diisopropanolamine (EDIPA), N,N,N',N'-tetrahydroxyethylethylenediamine (THEED), and mixtures thereof. It also includes hydrates of the above-mentioned additives, such as magnesium chloride including dried magnesium chloride, such as magnesium chloride hexahydrate, and calcium chloride including CaCl2·xH2O, where x is a value from 0 (inclusive) to 6 (inclusive). It also includes solutions of the above-mentioned additives in water or other solvents and suspensions in water or other liquids, such as magnesium chloride including aqueous solutions of magnesium chloride, calcium chloride including aqueous solutions of calcium chloride known as saline solutions; and triisopropanolamine (TIPA) including aqueous solutions of triisopropanolamine (TIPA).

[0075] In one specific embodiment, the accelerator is selected from calcium chloride, triethanolamine, and triisopropanolamine, and mixtures thereof. Advantageously, the accelerator is a mixture of calcium chloride, calcium chloride, and triethanolamine, or a mixture of calcium chloride and triisopropanolamine, and even more advantageously, calcium chloride.

[0076] As a result, in a particularly preferred embodiment, the substrate is diatomaceous earth and the moisture absorption promoter is calcium chloride.

[0077] In one specific embodiment, the accelerator is hygroscopic or deliquescent and has a particle size of 1 μm to 500 μm and a di of at least 8 μm, preferably at least 12 μm, preferably 15 μm to 80 μm. 50 Advantageously, the particle size of the accelerator is larger than the pore diameter of the substrate; more specifically, the particle size d of the accelerator... 50 The average pore size d of the substrate 50 .

[0078] In an advantageous embodiment, the weight ratio of the substrate (S) to the accelerator (A) is 0.01-5.

[0079] When the accelerator is calcium chloride, the weight ratio of the substrate (S) to the calcium chloride accelerator (Acl) is advantageously 0.2-5.

[0080] When the accelerator is an alkanolamine, the weight ratio of the substrate (S) to the alkanolamine accelerator (Aam) is advantageously 0.01-3.

[0081] Release of promoter

[0082] According to the present invention, at least 80% by weight of the accelerator dissolves after the free-flowing powder composition is immersed in water at 20°C for 15 minutes, provided that the free-flowing powder composition is immersed in a certain amount of water, the amount of water being sufficient to make it impossible to reach the saturation concentration of the accelerator.

[0083] For example, a method for evaluating the release of an accelerator from a free-flowing powder composition includes the following steps:

[0084] Step 1: Identify and quantify the accelerators or mixtures of accelerators contained in the free-flowing composition.

[0085] • Step 2: Measure the amount of accelerator released from the free-flowing powder composition over time.

[0086] The identification and quantification of the accelerator in step 1 can be performed by analyzing the free-flowing composition using any method well known to those skilled in the art. For example, such methods may include, but are not exhaustive, X-ray fluorescence, X-ray diffraction, infrared spectroscopy, titration, thermogravimetric analysis or differential thermogravimetric analysis, gas or liquid chromatography, ion chromatography, inductively coupled plasma optical / atomic or mass spectrometry (ICP-OES; ICP-AES or ICP-MS) spectroscopy, which is performed after the accelerator has been ground and / or liquid extracted in water or solvent.

[0087] The amount of accelerator is then expressed as an anhydrous content; for example, in a free-flowing composition containing calcium chloride hexahydrate as an accelerator, the amount of accelerator is expressed as the weight of anhydrous calcium chloride in the free-flowing composition.

[0088] Step 2 can be carried out by pouring the free-flowing composition into stirred distilled water at 20°C and atmospheric pressure. Importantly, the amount of free-flowing composition added should be such that the total amount of accelerator contained in the free-flowing composition is below the water saturation concentration of the accelerator, and the amount of accelerator dissolved in the water is determined after 15 minutes by in-situ measurement of the concentration of the corresponding cation or anion using an anion- or cation-sensitive probe, or non-in-situ after filtering the suspension and quantifying the accelerator dissolved in the resulting solution using any suitable technique.

[0089] For example, in the case of a free-flowing composition containing a chloride accelerator of calcium, potassium, magnesium, or sodium, a certain amount of the free-flowing composition (expressed in anhydrous form) containing 8 g of any of the above accelerators is added to 250 ml of distilled water in a borosilicate glass beaker. The resulting suspension is stirred for 15 minutes at 20°C using a magnetic stirrer rotating at 60 to 200 rpm. After 15 minutes, chloride ions (Cl) generated by the chloride accelerator of calcium, potassium, magnesium, or sodium are measured in situ using a chloride ion-sensitive immersion sensor. - The content of ) is then calculated. The amount of accelerator present in the free-flowing composition is then calculated.

[0090] For example, in the case of a free-flowing composition containing an alkanolamine accelerator, a certain amount of the free-flowing composition (expressed in anhydrous form) containing 1 g of the above accelerator is added to 250 ml of distilled water in a borosilicate glass beaker and stirred for 15 minutes. The resulting aqueous mixture is centrifuged to extract a solution free of solid particles. The amount of accelerator in the solution is determined by a method detailed in ASTM D7599-16 (2017). The amount of accelerator present in the free-flowing composition is then calculated.

[0091] Method for preparing free-flowing powder compositions

[0092] The present invention also relates to a method for preparing the above-described free-flowing powder composition.

[0093] Free-flowing powder compositions can be prepared by mixing the accelerator of the present invention with the substrate of the present invention. Mixing can be carried out in any suitable manner known to those skilled in the art.

[0094] According to an embodiment, the preparation of the free-flowing powder of the present invention includes the step of contacting a solid substrate with a solid hygroscopic or deliquescence accelerator, such that the particle size of the substrate and the hygroscopic or deliquescence accelerator is constant during the contact step. Preferably, this contact is carried out in a solid state.

[0095] The term "solid" refers to the contact process occurring in the absence of a solvent. In other words, the substrate and / or hygroscopic or deliquescent accelerator may contain moisture, but it will be in particulate form.

[0096] The term "constant" means that the average particle size is substantially the same before and after the contact step. In other words, in the context of this invention, if the average particle size d after the contact step... 50 If the reduction is less than 20%, the particle size is considered constant.

[0097] In a preferred embodiment, the step of contacting the substrate with the hygroscopic or deliquescent accelerator in a dry state is performed by mixing them.

[0098] Mixing in a dry state refers to any intermittent or continuous mixing method that allows for the production of a uniform volume distribution of particles with several properties. Within the framework of this invention, and not exhaustively, the following types, brands, and models of intermittent mixers may be used: a high-powered mixer from Eirich, model RV; a belt kneader from WAM Group, model WBH; a high-powered mixer from Sofraden, model MIB; a belt kneader from Sofraden, model MHR; and a soft mixer from Sofraden, model Sofragir. Within the framework of this invention, and not exhaustively, the following types, brands, and models of continuous mixers may be used: a high-powered mixer from WAM Group, model WAH; and a high-powered mixer from Eirich, model RV.

[0099] In comparison, the method disclosed in US 1,791,630 produces a finer powder through a grinding step. In other words, the particle size is reduced, and the porous material is broken down into smaller particles. Furthermore, the moisture-absorbing promoter is smaller and humidifies more quickly, allowing it to penetrate into the pores and largely remaining off the surface.

[0100] In fact, co-grinding of easily grindable compounds such as CaCl2 with less grindable compounds such as diatomaceous earth results in CaCl2 particles that are much finer than the size of diatomaceous earth.

[0101] According to another embodiment, the preparation of the free-flowing powder of the present invention includes the step of contacting a solid substrate with a liquid accelerator.

[0102] This preparation preferably includes the step of spraying accelerator droplets onto a substrate, followed by a drying step.

[0103] In the latter method, the accelerator is in a liquid state, so the liquid accelerator can be used as is or diluted in a solvent, preferably water. In the case of hygroscopic and deliquescent accelerators, the same dissolution step is performed before the spray droplet step. In one embodiment, the hygroscopic or deliquescent accelerator is dissolved in water at a concentration higher than 50% of its saturated solubility in water at 20°C and 1.013 bar.

[0104] According to the embodiments, the method for preparing a free-flowing powder composition as described above therefore includes the step of spraying an accelerator onto a substrate, said accelerator being liquid and used as is, or said accelerator being liquid, hygroscopic or deliquescent and diluted in a solvent, preferably water.

[0105] Using these two methods, the accelerator is essentially deposited on the outer surface of the porous substrate, and the penetration of the accelerator into the pores is strongly restricted.

[0106] In contrast, the methods disclosed in CN106348643, CN110104988, and CN109250964 also involve hygroscopic or deliquescent accelerators in liquid form, including the step of preparing a substrate and a dispersion of the hygroscopic or deliquescent accelerator. As a result, in the dispersion, the hygroscopic or deliquescent accelerator penetrates into the pores of the substrate, and most of the hygroscopic or deliquescent accelerator is not located on the surface.

[0107] Uses of free-flowing powder compositions

[0108] The present invention also relates to the use of the above-mentioned free-flowing powder composition as an additive to mortar or concrete compositions to provide promoting effects, anti-aging effects and anti-dust effects.

[0109] Therefore, preferably, the liquid, hygroscopic or deliquescent accelerator of the free-flowing powder composition of the present invention is capable of being used as an accelerator in mortar or concrete compositions including hydraulic binders.

[0110] Mortar or concrete composition

[0111] This invention also relates to dry mortar or concrete compositions, particularly cement-based tile adhesives, grouting materials, self-leveling base layers, self-leveling top layers, priming plasters, repair mortars, thin-bonding mortars or concretes, screeds, wall leveling agents for internal or external use, non-shrink grouts, thin-bonding mortars, waterproof mortars, or anchoring mortars, comprising a hydraulic binder, the aforementioned free-flowing powder composition, and particles with a d50 of 50 μm to 3 mm.

[0112] The particles can be any particles commonly used in hydraulic compositions. Typical particles include, for example, rocks, crushed stone, gravel, slag produced or converted from iron, steel, copper or other metals, sand, especially quartz sand, river sand and / or manufactured sand, recycled concrete, glass, expanded glass, pumice, perlite, vermiculite, and / or fine particles, such as ground limestone, ground dolomite, and / or ground alumina, or mixtures thereof.

[0113] In a preferred embodiment, the particles are quartz sand, river sand, artificial sand such as that from granite or limestone, or mixtures thereof.

[0114] Hydraulic binders are advantageously selected from Portland cement, alumina cement, sulfoaluminate cement, lime, sulfate and / or auxiliary cement or pozzolanic materials.

[0115] Portland cement can be any cement conforming to standard EN 197-1. In particular, CEM I, CEM II, CEM III, CEM IV and / or CEM V types, especially CEM I (also known as standard Portland cement - OPC). Portland cement conforming to other international standards, such as ASTM standards or Chinese standards, may also be used.

[0116] The term "alumina cement" specifically refers to cement having an aluminum content of at least 30% by weight, particularly at least 35% by weight, and especially 35-58% by weight, as measured in Al2O3. Preferably, the alumina cement is alumina cement according to standard EN 14647.

[0117] Preferably, the sulfoaluminate cement is calcium sulfoaluminate cement (CSA).

[0118] The term lime refers to natural hydraulic lime, prepared lime, hydraulic lime and air lime, as described in standard EN 459-1:2015.

[0119] More specifically, the term "natural hydraulic lime (NHL)" refers to a material derived solely from mineral sediments and naturally containing all elements (typically limestone, clay, and impurities) to produce hydraulic lime during calcination, typically at temperatures between 800°C and 1200°C. Natural hydraulic lime can be used as a hydraulic binder in mortar compositions. In the context of this invention, NHL belongs to any of the NHL2, NHL3.5, or NHL5 classes according to EN 459-1:2015.

[0120] The term "hydraulic lime (HL)" refers to a material that can be produced from limestone by thermal decomposition at temperatures ranging from 800°C to 1200°C in a process known as calcination. Hydraulic lime is essentially composed of CaO and / or Ca(OH)₂ and additional siliceous and / or aluminosilicate materials. In the context of this invention, HL falls under any one of categories HL2, HL3.5, or HL5 according to EN 459-1:2015.

[0121] Prepared lime (FL) refers to a material with hydraulic properties, which is based on air lime or NHL with the addition of additional hydraulic and / or pozzolanic materials.

[0122] In the context of this invention, sulfate is a material containing a certain amount of sulfate. It is particularly an inorganic salt of sulfate or sulfuric acid. Preferred sulfate sources herein are alkali metal salts of sulfuric acid, alkaline earth metal salts of sulfuric acid, aluminum sulfate, aluminum hydroxide, or alum (XAl(SO4)2·12H2O, where X is potassium or ammonium). These sulfates may exist in hydrated form. Sulfate sources are selected from sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and mixtures thereof. Particularly preferred sulfate sources are calcium sulfate. Calcium sulfate includes anhydrous gypsum, hemihydrate calcium sulfate in α and β forms, dihydrate calcium sulfate, and any mixtures thereof. Calcium sulfate may be based on LGD gypsum, phosphogypsum, fluorogypsum, and natural gypsum. Anhydrite is a mineral composed of CaSO4 without any water of crystallization.

[0123] Auxiliary cement-based materials refer to materials that can be hydrated in the presence of other cement or pozzolanic materials. This means that they can react with calcium hydroxide at room temperature to form compounds with cementing properties. These compounds are selected from granulated blast furnace slag (GGBS), steelmaking slag, alkaline oxygen-generating slag, steel ladle slag, argon-oxygen deashing furnace slag, vacuum oxygen deashing furnace slag, fly ash, silica fume, pyrolytic silica, precipitated silica, rice husk ash, pozzolanic ash, pumice, zeolite, crushed glass, calcined clay, especially metakaolin, and mixtures thereof.

[0124] A mixture of Portland cement, alumina cement, sulfoaluminate cement, lime, sulfate and / or auxiliary cement or pozzolanic materials may be used. There are no particular restrictions on the weight ratio of Portland cement, alumina cement, sulfoaluminate cement, lime, sulfate and / or auxiliary cement or pozzolanic materials, and they may vary in a wide range.

[0125] In a preferred embodiment, the content of the hydraulic binder is 10% to 60% by weight, the content of the free-flowing powder composition is 0.1% to 15% by weight, and the content of particles is 30% to 90% by weight.

[0126] In one specific embodiment, the dry mortar or concrete composition according to the invention further comprises at least one additive selected from fillers, plasticizers and / or superplasticizers, air-entraining agents, defoamers, stabilizers, rheology modifiers, especially thickeners, water-reducing agents, redispersible polymer powders, accelerators, retarders, water-resistant agents, strength-enhancing additives, fibers, dust removers, foaming agents, pigments, corrosion inhibitors, biocides, and chromium (VI) reducing agents.

[0127] In a preferred embodiment, the superplasticizer is selected from lignin sulfonates, sulfonated vinyl polymers, polynaphthalene sulfonates, sulfonated melamine-formaldehyde condensates, polyethylene oxide phosphonates, polycarboxylic acid ethers (PCE), or mixtures thereof. Preferably, the hydraulic composition of the present invention comprises PCE.

[0128] In a preferred embodiment, the thickener is selected from starch, pectin, amylopectin, modified starch, cellulose, modified cellulose such as carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, methyl hydroxyethyl cellulose, casein, xanthan gum, diutan gum, welan gum, galactomannan such as guar gum, tara gum, fenugreek gum, locust bean gum or cassia gum, alginate, tragacanth gum, dextran, polydextrose, layered silicates such as sepiolite, bentonite or vermiculite, and mixtures thereof.

[0129] In a preferred embodiment, the retarder is selected from sugar acids, sugars, sugar alcohols, hydroxycarboxylic acids or their salts, phosphates, phosphonates, borates and amines. Preferably, the retarder is selected from gluconic acid, citric acid, tartaric acid or their respective sodium salts.

[0130] The redispersible polymer is a powder. The term "redispersible polymer powder" refers to a powder containing a polymer that forms a stable dispersion upon introduction into water. Redispersible polymer powders include not only the polymer but also typically mixtures thereof with, for example, protective colloids, emulsifiers, and carrier materials. Redispersible polymer powders can be prepared, for example, by spray drying a polymer dispersion, as described in patent application EP1042391. Suitable redispersible powders are available, for example, under the trade name Vinnapas from Wacker Chemie AG. The use of redispersible powders of synthetic organic polymers is preferred for the purposes of this invention. Synthetic organic polymers within the scope of this invention can be produced by free radical polymerization of monomers selected from ethylene, propylene, butene, isoprene, butadiene, styrene, acrylonitrile, acrylic acid, methacrylic acid, acrylates, methacrylates, vinyl esters, and vinyl chloride. Preferably, the synthetic polymer is a copolymer synthesized from two or more, preferably two different, monomers. The sequence of the copolymer can be alternating, block, or random. Preferred synthetic organic polymers are copolymers of vinyl acetate and ethylene, vinyl acetate and ethylene and methyl methacrylate, vinyl acetate and ethylene and vinyl ester, vinyl acetate and ethylene and acrylate, vinyl chloride and ethylene and vinyl laurylate, vinyl acetate and vinylveratate, acrylate and styrene, acrylate and styrene and butadiene, acrylate and acrylonitrile, styrene and butadiene, acrylic acid and styrene, methacrylic acid and styrene, styrene and acrylate, and styrene and methacrylic acid. The glass transition temperature (Tg) of the synthetic organic polymer can vary over a wide range. A suitable synthetic organic polymer may have a Tg of, for example, -50°C to +60°C, preferably -45°C to +35°C, and more preferably -25°C to +15°C.

[0131] The present invention also relates to a wet mortar or concrete composition obtained by mixing the dry mortar or concrete composition of the present invention with water, preferably at a water / powder ratio of 0.1-0.6, more preferably 0.2-0.5, and more preferably 0.2-0.35.

[0132] The present invention also relates to a hardened body obtained by hardening a wet mortar or concrete composition according to the invention. Example

[0133] Example 1: Release and efficiency of the promoter

[0134] Three diatomaceous earth samples combined with calcium chloride (CaCl2) were prepared. In sample E1, the free-flowing powder composition of the present invention was prepared by mixing 100 g of diatomaceous earth with 100 g of CaCl2. In sample CE1, 100 g of diatomaceous earth and 100 g of CaCl2 were co-ground as disclosed in US 1,791,630. In sample CE2, a suspension of 100 g of diatomaceous earth and 100 g of CaCl2 in 300 mL of water was prepared, stirred, and dried at 200 °C for 24 hours as described in CN106348643, CN110104988, and CN109250964. Sample CE3, consisting of pure CaCl2, was also prepared.

[0135] Each of the four samples was added to water at 20°C to ensure that the total amount of CaCl2 (expressed in anhydrous form) was equal, i.e., 8 g of pure CaCl2 in 250 mL of water, 8 g of CE3 in 250 mL of water, and 16 g of E1, CE1, and CE2 in 250 mL of water. The resulting compositions were maintained with stirring while the chloride concentration was continuously recorded and expressed as chloride concentration in mol / L ([Cl... - The chloride was generated from the CaCl2 dissolved in water from the four samples. Therefore, for samples E1, CE1, and CE2, the change in chloride concentration over time reflects the release of calcium chloride from the diatomaceous earth.

[0136] like Figure 1 As shown in the graphs, for pure CaCl2 (CE3) and for the present invention (E1), the chloride concentration reaches greater than 0.28 mol / L in less than 5 minutes, indicating similar dissolution of CaCl2 in both samples. Therefore, CaCl2 is completely released from the free-flowing powder of the present invention (E1). In the case of samples CE1 and CE2, the maximum concentrations reached after stirring for 40 minutes were 0.16 mol / L and 0.22 mol / L, respectively, indicating only partial and delayed release of CaCl2. Therefore, the present invention (E1) does not waste CaCl2 compared to the prior art (CE1 and CE2).

[0137] Therefore, it is clear that the combination of diatomaceous earth and calcium chloride varies depending on the preparation method. The faster release and higher amount of calcium chloride indicate that, compared to prior art samples CE1 and CE2, in the sample (E1) according to the invention, most of the calcium chloride is located on the outer surface of the diatomaceous earth, rather than inside the pores.

[0138] Alternatively, when calcium chloride dissolves in water, an increase in solution temperature is observed because this is a highly exothermic process.

[0139] Four 80 mL solutions containing 20 g of CaCl2 were prepared: 20 g of sample (CE3) was added to 80 mL of water, and 40 g of samples E1, CE1, and CE2 were added to 80 mL of water. The three samples E1, CE1, and CE2 were then compared with free CaCl2 (CE3).

[0140] like Figure 2 As shown in the curves, in the case of free CaCl2, the peak of the temperature curve appears at approximately 4 minutes, while in the case of sample E1 of the present invention, the peak of the temperature curve appears at approximately 6 minutes. The peaks of the temperature curves of samples CE1 and CE2 appear after approximately 15 minutes and 10 minutes, respectively. Therefore, compared with the prior art (CE1 and CE2), the present invention (E1) releases CaCl2 more quickly.

[0141] In the same manner as described above, compared with samples CE1 and CE2 according to the prior art, the faster release and greater release of calcium chloride indicate that in the sample (E1) according to the invention, most of the calcium chloride is located on the outer surface of the diatomite, rather than inside the pores.

[0142] Example 2: Promoting Effect

[0143] Five mortars were prepared: mortar containing sample E1 (ME1), i.e., the free-flowing powder of this invention; mortar containing sample CE1 (MCE1); mortar containing sample CE2 (MCE2); mortar containing sample CE3 (pure CaCl2); and mortar without CaCl2 (MCE4). All compositions are given in Table 1 below. When preparing these five mortars, all powder materials were weighed according to their respective amounts and mixed in a mixing bowl on a Hobart mixer at 20°C and 50% relative humidity (RH) for 3 minutes. A visually homogeneous dry mixture was obtained in all mortars. Water was added to this dry mixture in an amount such that the water-to-powder weight ratio (w / p ratio) is as shown in Table 1. Mixing was then continued for another 3 minutes. The resulting wet mortar was poured into molds to allow for the measurement of the initial Vicat needle setting time according to EN196-3 (in Vicatronic L0722, from Controlab), and poured into 4×4×4 cm molds. 3 The mortar is placed in a mold and cured in a sealed plastic bag for 48 hours. After 48 hours, the hardened mortar is removed from the mold, and the compressive strength of a portion of it is tested. The other portion is cured in a sealed plastic bag until the compressive strength is tested 14 days after wet mixing.

[0144] Compressive strength was measured after the curing times shown in Table 1 and under the conditions described above. Measurements were taken on a 40x40x160mm prism according to EN 196-1:2016 and expressed in MPa.

[0145]

[0146] Table 1

[0147] As can be clearly seen from the initial Vicat setting time and compressive strength results in Table 1, mortars MCE3 and ME1 have very similar setting times, early strength (48 hours), and 14-day strength, which indicates that CaCl2 in mortar ME1 is released almost as quickly as pure CaCl2 in mortar MCE3.

[0148] It is equally evident that mortars MCE1 and MCE2, formulated with CaCl2 sources according to existing technology, exhibit much longer setting times and slower strength development.

[0149] Therefore, it is clear that the combination of diatomaceous earth and calcium chloride varies depending on the preparation method. Due to the free-flowing powder of this invention, a faster and higher promoting effect on setting time and strength development kinetics is achieved in the mortar of this invention.

[0150] Furthermore, when comparing MCE3 and ME1, the mortar of the present invention appears to exhibit a shorter setting time and higher early strength after 2 days than the mortar prepared with pure CaCl2. These results demonstrate the positive effect of pre-combining a high specific surface area substrate (diatomaceous earth), which acts as a germinative surface near the promoting additive (CaCl2).

[0151] Furthermore, comparing mortars MCE1 and MCE2 with mortar MCE4, it was concluded that the CaCl2 in mortars MCE1 and MCE2 did indeed have a promoting effect, but it had a factor of less than 2 for the initial setting time. Moreover, the compressive strength in mortars MCE1 and MCE2 was higher, but not as high as that in mortar MCE3 (pure CaCl2) and the mortar of the present invention.

[0152] Example 3: Evaluation of free-flowing powder

[0153] Seven samples were prepared as shown in Table 2 below.

[0154]

[0155]

[0156] Table 2

[0157] Sample CE3 corresponds to pure CaCl2, and sample CE5 corresponds to a premix consisting of CaCl2, a waterproofing agent, and mineral fillers, which is a commonly used accelerator formulation in the mortar industry. Samples E2, E3, and E4 correspond to the compositions of the present invention, containing CaCl2 on different substrates. Samples E5 and E6 correspond to the compositions of the present invention, containing TEA or TIPA solution on a diatomaceous earth substrate.

[0158] Each sample was placed in a thin (5 mm) layer at 20 °C and 50% relative humidity (RH), and their free-flow behavior was rated according to the following scores: 0 = visible liquid phase; 1 = no free flow: dry state + agglomeration; 2 = difficult to dry and free flow: some agglomeration; 3 = perfectly free flow.

[0159] As shown in Table 2 above, samples according to the invention remained in a free-flowing powder state for up to 14 days, and in some cases even up to 20 days, under high exposure to a humid atmosphere (thin layer, high contact surface). Furthermore, the invention is more effective and longer-lasting than known practices, which include premixing the moisture-absorbing material with a waterproofing agent and fine mineral fillers, as shown in sample CE5.

[0160] Example 3: Anti-aging effect of Portland cement composition

[0161] Portland cement, premixed with several hygroscopic additives, was exposed to air for 6 days at 35°C and 75% RH in the form of a thin layer (2 mm). Four different samples were prepared, as shown in Table 3 below.

[0162]

[0163]

[0164] Table 3

[0165] Moisture-absorbing additives that trap moisture from the air can cause liquid formation in their vicinity. This liquid (a solution of the compound in water) can react with the cement, causing the cement to age and lose its overall reactivity. This is visible as dark spots that highlight the presence of the liquid and localized hydration of the cement.

[0166] Although CaCl2 has high hygroscopic and deliquescent properties, when introduced in the form of this invention, the amount of moisture absorbed by the additive cement is greatly reduced, thus greatly reducing aging.

[0167] Example 4: Promoting and Anti-aging Effects of Dry Mortar Compositions

[0168] Example 4-1: Acceleration in plastering compositions

[0169] This embodiment provides the performance of the plastering composition of the present invention compared to prior art facade plastering (FC) compositions.

[0170] Plastering CE9 exemplifies the prior art FC, which is based on a mixed binder of ordinary Portland cement / hydraulic lime promoted by calcium nitride.

[0171] Plastering E8 exemplifies the accelerator system of plastering CE9, which has been replaced by the free-flowing powder of the present invention (diatomaceous earth and CaCl2 initially dry-mixed in a 50 / 50 weight ratio).

[0172] All powder materials of compositions CE9 and E8 were weighed individually and mixed in a mixing bowl on a Hobart mixer at 20°C and 50% relative humidity (RH) for 3 minutes. A visually homogeneous dry mixture was obtained. A certain amount of water was added to this dry mixture to obtain the water-to-powder weight ratio (w / p ratio) shown in Table 4 below. Mixing was then continued for another 3 minutes. The resulting wet plaster was poured into a mold, allowing continuous measurement of the ultrasonic propagation speed through the plaster during the hardening process (using an Ultratest IP-8 ultrasonic multiplier tester). The time to reach an ultrasonic propagation speed of 1500 m / s was recorded, as this speed represents the consistency required for convenient and visually effective artificial smoothing and finishing of facade plaster surfaces.

[0173]

[0174] Table 4

[0175] Clearly, using the free-flowing powder composition according to the invention as an additive can promote plastering more effectively than calcium nitride in the prior art, i.e., reduce the hardening time required for surface finishing.

[0176] Example 4-2: Promoting and Anti-aging Effects of Tile Adhesive Compositions

[0177] This embodiment provides an explanation of the performance of the formulation of the present invention compared to existing formulations of cement-based tile adhesives (CTA).

[0178] CTA CE10 illustrates a prior art CTA based on a mixed binder Portland cement / ground granulated blast furnace slag (OPC / GGBS), which is promoted by a combination of calcium formate (Ca(HCO2)2) and sodium chloride (NaCl).

[0179] CTA E9 illustrates a CTA in which the accelerator system of plastering CE10 has been replaced by the free-flowing powder of the present invention (diatomaceous earth and CaCl2 initially dry-mixed in a 50 / 50 weight percentage ratio).

[0180] CTA E10 corresponds to CTA E9, but the free-flowing powder according to the invention has been artificially aged (3 aging cycles) before being introduced into CTA E10. The composition of each CTA is detailed in Table 5 below.

[0181] The premix of the present invention and CTA were tested in their freshly prepared state and after three accelerated aging cycles.

[0182] One cycle of accelerated aging refers to:

[0183] - Packaged in standard paper and polyethylene film bags, filled only to 1 / 3 of the maximum volume capacity (this is to maximize air / dry mix contact).

[0184] - Store at 35°C and 80% RH for 6 days.

[0185] -Then store at 5°C and 80% RH for 24 hours to promote the condensation of moisture inside the bag.

[0186] The performance of the tested CTA was evaluated as follows:

[0187] - The viscosity after mixing serves as an indicator of ease of application.

[0188] - Initial adhesive strength at 5°C, tested 24 hours after application, serves as an indicator of the reactivity of CTA under challenging conditions.

[0189]

[0190]

[0191] Table 5

[0192] It can be seen that, for the same addition level (1.6% by weight), using the free-flowing powder composition of the present invention as an additive makes the accelerator more effective than using prior art accelerators, because CTA E9 showed better performance (0.43 MPa initial bond strength) than CTA CE10 (0.37 MPa), which did not significantly change the application behavior (no significant change in viscosity).

[0193] Furthermore, the CTA E9 according to the invention undergoes far less aging than the prior art CTA CE10, which experiences a significant decrease in applicability (+19% viscosity after aging) and even more significant performance degradation (-28% adhesive strength). In contrast, the viscosity and strength of CTA E9 do not change significantly (2% and 9% changes, respectively).

[0194] Furthermore, even based on a pre-aged accelerator system (E10), it achieves better performance than the existing technology CTA CE10.

[0195] It can be noted that the CTA of the present invention based on the pre-aged free-flowing powder composition (E10) exhibits very similar properties to the CTA E9 based on the freshly prepared free-flowing powder composition of the present invention. This confirms the inherent anti-aging properties of the free-flowing powder composition of the present invention.

[0196] Example 5: Anti-aging effect in wet mortar composition

[0197] Several CTA mortars were prepared and mixed with the same amount of water (21.5% by weight) according to the same procedure. The composition is given in Table 6 below.

[0198] Immediately after wet mixing, the wet mortar is placed in a Vicat needle setting time measuring device (EN 196-3 (in Vicat L0722, from Controlab)) and a unit equipped with ultrasonic velocity measurement (in IP-8 ultrasonic multiplier tester, from Ultratest).

[0199] This is to accurately measure the time required for each type of mortar to solidify (Vicat needle test) or harden to allow an ultrasonic propagation speed of 500 m / s to pass through the sample.

[0200] Testing was conducted immediately after the production of CTA dried mortar (test marked as before aging) or after three cycles of aging conditions, which have been described in Example 3 above.

[0201]

[0202]

[0203] Table 6

[0204] All CTA mortar compositions contain the same amount of accelerator (0.8% by weight), except for CE11 (2 accelerators, totaling 1.6% by weight) and CE12, which contain no accelerator.

[0205] CE11 is a strongly accelerated CTA mortar that combines calcium formate as a Portland cement accelerator with a special additive that promotes the activation and hydration of GGBS.

[0206] CE12 contains no accelerators.

[0207] CE13 contains pure CaCl2.

[0208] E11 contains 0.8% CaCl2 provided in the form of this invention, i.e., a dry premix of 50% CaCl2 and 50% diatomaceous earth M.

[0209] CE14 contains calcium acetate, and CE15 contains calcium nitride. Like calcium formate, they are commonly used additives in CTA.

[0210] To better highlight the results listed in Table 6 above, Figure 5 The graph shown represents velocity versus time. Figure 5 As can be seen from the wet mortar (E11) according to the present invention:

[0211] • The fastest solidification was shown, both measured by Vicat needle (675 minutes) or by ultrasonic speed (682 minutes).

[0212] • It showed faster setting compared to mortar containing the same amount of CaCl2 added directly to the dry mix (CE13). This confirms the positive effect of the pre-composition of the high specific surface area substrate (diatomaceous earth), which acts as a germination surface near the additive (CaCl2).

[0213] • It showed faster setting compared to mortar containing two accelerators (CE11), indicating that the invention is effective not only for Portland cement but also for GGBS binders.

[0214] • This demonstrates the lowest hardening delay caused by pre-aging (+105 minutes and +46 minutes, respectively, when tested using a Vicat needle or ultrasonic propagation speed). This demonstrates the anti-aging effect of the invention, which is due to the moisture absorption and storage effect in the pores of the diatomaceous earth.

[0215] It can be noted that the aging effect in E11 is very low compared to CE13 containing the same amount of CaCl2, which indicates that the present invention allows the introduction of CaCl2 without the aging effect induced by its high hygroscopic and deliquescent behavior.

[0216] It should also be noted that the mortar based on the present invention (E11) suffers less aging (i.e., less impact on setting time) than all other mortars (CE11, CE14 and CE15, which contain calcium formate, calcium acetate and calcium nitrite, respectively) containing less moisture accelerator than CaCl2.

[0217] Example 6: Effect of the weight ratio of substrate to accelerator

[0218] According to the present invention, another sample (E12) of diatomaceous earth combined with calcium chloride (CaCl2) was prepared. In sample E12, the free-flowing powder composition of the present invention was prepared by mixing 75g of diatomaceous earth with 25g of CaCl2.

[0219] According to the present invention, another sample (E13) of diatomaceous earth combined with triisopropanolamine (TIPA) has been prepared. In sample E13, the free-flowing powder composition of the present invention was prepared by mixing 80 g of diatomaceous earth with 20 g of TIPA.

[0220] Five additional mortars were prepared: mortar E1, containing the free-flowing powder of the present invention (ME1B); two mortars E12 (ME12 and ME12B); and two mortars E13 (ME13 and ME13B). All compositions are given in Table 7 below. The compositions of mortars ME1, MCE3, and MCE4 are also indicated in Table 7.

[0221]

[0222]

[0223] Table 7

[0224] Mortars MCE3, ME1, and ME12 contain the same amount of calcium chloride (1.5% dry composition), while ME1B and ME12B contain 0.75% CaCl2.

[0225] Clearly, for mortars containing the same amount of CaCl2, the effects of the additive are similar, based on observations of the initial setting time and compressive strength of the Vicat needles. It is evident that the mortars of the present invention (ME1 and ME12) exhibit shorter setting times and higher early strength after 2 days than the mortar containing the same amount of CaCl2 (mortar MCE3), confirming the positive effect of the pre-bonding of the high specific surface area substrate (diatomaceous earth), which promotes the germination of the surface near the additive (CaCl2).

[0226] Mortars containing a small amount of CaCl2 (ME1B and ME12B) and mortars containing different amounts of another accelerator, TIPA (ME13 and M13B), also exhibit suitable properties.

[0227] Example 7: Dust Removal Effect

[0228] Dry-mixed mortar or concrete prepared for mixing with water-based agents typically contains very fine particles, such as particles smaller than 10 μm, or even smaller than 5 μm; this mainly comes from binders, namely Portland cement, alumina cement, and ground granular blast furnace slag, which generate dust during processing.

[0229] To limit or suppress dust, mortar and concrete may contain special additives, such as oils, specifically designed to agglomerate the finest particles, which may exhibit the disadvantage of increased wetting and / or setting times.

[0230] Six dry mortar compositions were prepared. The ratio of binder to additive was selected to reflect standard methods in the art, and when quantifying the dust-suppressing ability of the accelerator, the standard dosage of the accelerator or existing dust suppressant was reflected. The particle size distribution of each sample in the dry state was analyzed using a laser particle size analyzer. The compositions and particle size distributions of the dry mortars are listed in Table 8 below.

[0231]

[0232] Table 8

[0233] As can be seen from Table 8, the dry mortars (ME4, ME5, and ME6) of this invention containing the newly prepared accelerator have reduced dust levels:

[0234] • Because the volume of particles smaller than 10 μm (18.67%, 18.45%, and 17.23% for CaCl2, TEA, and TIPA-based additives, respectively) and particles smaller than 5 μm (9.16%, 6.01%, and 6.13% for CaCl2, TEA, and TIPA-based additives, respectively) is similar to the volume of particles in mortar MCE17 containing prior art dust suppressants (oils), which are 19.94% and 8.35%, respectively.

[0235] • Because the volume of particles smaller than 10 μm (18.67%, 18.45%, and 17.23% for CaCl2, TEA, and TIPA-based additives, respectively) and particles smaller than 5 μm (9.16%, 6.01%, and 6.13% for CaCl2, TEA, and TIPA-based additives, respectively) is similar to that of particles in mortar MCE16 containing standard moisture-absorbing accelerators such as calcium formate, at 22.7% and 14.35%, respectively.

[0236] As can also be seen from Table 8, the dry mortar (ME4B) with a 3-day aging accelerator according to the present invention has a reduced dust level:

[0237] • Because the volume of particles smaller than 10 μm (16.33%) and particles smaller than 5 μm (5.98%) is lower than the particle volume in mortar MCE17 containing prior art dust suppressants (oils), which are 19.94% and 8.35%, respectively.

[0238] • Because the volume of particles smaller than 10 μm (16.33%) and particles smaller than 5 μm (5.98%) is smaller than the volume of particles in mortar MCE16 containing standard moisture accelerators such as calcium formate, which are 22.7% and 14.35%, respectively.

Claims

1. A method of preparing a free-flowing powder composition comprising at least one substrate having pores and an outer surface between the pores, wherein the outer surface is functionalized with at least one accelerator for a hydraulic setting composition, the accelerator being hygroscopic or deliquescent, and wherein at least 80 wt% of the accelerator is dissolved after immersing the free-flowing powder composition in water at 20°C for 15 minutes, provided that the free-flowing powder composition is immersed in water in an amount sufficient to make it impossible to reach a saturated concentration of the accelerator; the method comprising the step of contacting a solid substrate with a solid hygroscopic or deliquescent accelerator, such that the particle size of the substrate and the hygroscopic or deliquescent accelerator is constant during the contacting step; wherein the particle size d of the accelerator is 50 higher than the average pore diameter d of the substrate 50 , wherein the substrate is selected from the group consisting of calcined clay, zeolite, expanded perlite, precipitated silica, ground calcium carbonate, precipitated calcium carbonate, diatomite, calcined diatomite and pulverized cementitious foam.

2. The method according to claim 1, wherein the method comprises the step of contacting a solid substrate with a solid hygroscopic or deliquescent accelerator in solid state.

3. The method of claim 1, wherein the substrate is a powder composed of porous particles having a d 50 iameter of at least 10 pm.

4. The method of claim 1, wherein the substrate is a powder composed of porous particles having a d 50 iameter of at least 15 pm.

5. The method of claim 1, wherein the substrate is a powder composed of porous particles having a d 50 iameter between 20 pm and 100 pm.

6. The method according to any one of claims 1-5, wherein the accelerator is selected from the group consisting of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium hydroxide, lithium sulfate, lithium carbonate, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, alkali metal nitrate, alkali metal nitrite, alkali metal thiocyanate, alkali metal silicate, and mixtures thereof.

7. The method according to any one of claims 1 to 5, wherein the accelerator is calcium chloride.

8. The method according to any one of claims 1 to 5, wherein the weight ratio of substrate to accelerator is from 0.01 to 5.

9. The method according to any one of claims 1 to 5, wherein the accelerator is calcium chloride and the weight ratio of substrate to calcium chloride accelerator is from 0.2 to 5.

10. Use of a free-flowing powder composition prepared according to the method of any one of claims 1 to 9 as an additive to a mortar or concrete composition to provide an accelerating effect, an anti-aging effect and / or a dust-proof effect.

11. A dry mortar or concrete composition comprising a hydraulic binder, a free-flowing powder composition prepared according to the method of any one of claims 1 to 9 and particles having a particle size dso of from 50 pm to 3 mm.

12. The dry mortar or concrete composition according to claim 11, which is a cement-based tile adhesive, a grouting material, a self-leveling underbase, a self-leveling render, a base plaster, a repair mortar, a screed, a shrinkage-compensating paste, a thin joint mortar, a waterproofing mortar or an anchoring mortar.

13. The dry mortar or concrete composition according to claim 11, wherein the content of the hydraulic binder is from 10 wt% to 60 wt%, the content of the free-flowing powder composition is from 0.1 wt% to 15 wt%, and the content of the particles is from 30 wt% to 90 wt%; wherein the sum of all ingredients comprised in the composition shall amount to 100 wt%.

14. A wet mortar or concrete composition obtained by mixing the dry mortar or concrete composition according to any one of claims 11 to 13 with water in a water / powder ratio of 0.1 to 0.

6.

15. The wet mortar or concrete composition according to claim 14 obtained by mixing the dry mortar or concrete composition according to any one of claims 11 to 13 with water in a water / powder ratio of 0.15 to 0.

5.

16. The wet mortar or concrete composition according to claim 14 obtained by mixing the dry mortar or concrete composition according to any one of claims 11 to 13 with water in a water / powder ratio of 0.15 to 0.

35.

17. A hardened body obtained by hardening the wet mortar or concrete composition according to claim 14.

Images