Method for producing a composition suitable as a setting and / or hardening accelerator for a hydraulic binder

Abstract

The invention relates to a method for producing a composition suitable as a setting and / or hardening accelerator for a hydraulic binder B2 comprising the following successive steps: (i) mixing particles of a hydraulic binder B1 and water, (ii) adding to the mixture obtained in step (i) a dispersant for dispersing the hydraulic binder B1 particles and an additive selected in the group consisting of alkanolamines, glycerol phosphate disodium and mixtures thereof, (iii) and mixing.

Description

[0001] METHOD FOR PRODUCING A COMPOSITION SUITABLE AS A SETTING AND / OR HARDENING ACCELERATOR FOR A HYDRAULIC BINDER

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns a method for producing a composition suitable as a setting and / or hardening accelerator for a hydraulic binder.

[0004] BACKGROUND OF THE INVENTION

[0005] Setting or hardening accelerators are used in mineral binders in order to accelerate the setting or hardening of binder compositions after mixing with water.

[0006] In particular, in cement hydration, the various cement clinker phases can react with water to form hardened cement phases such as calcium silicate hydrate, ettringite, calcium aluminate ferrite phases, monosulfate, and portlandite.

[0007] Due to their high specific surface area, some nanoparticles are capable of accelerating the kinetics of cement hydration by stimulating the nucleation and precipitation process of calcium silicate hydrate (CSH) as agglomerates during the initial hours of reaction. This acceleration leads to a densification of the matrix by filling faster the space between cement particles with hydrated phases; thus, accelerating compressive strength development and reducing capillary porosity.

[0008] The use of calcium silicate hydrate (CSH) seeds to accelerate the hydration of cement has been described in WO 2010026155. The approach described in WO 2010026155 relies on a reaction of a water-soluble calcium component with a water-soluble silicon component in aqueous solution in the presence of a water-soluble comb polymer suitable as a plasticizer for hydraulic binders. The downside of this process is that the final composition contains unwanted parts of unreacted salts from the production process.

[0009] EP3538499A1 describes a method for producing a setting and / or hardening accelerator for mineral binders from solid material including Portland cement. A requirement of this process is that the mineral solid is subject to a grinding process in a solid or liquid medium to comminute particle size to a very low size, typically less than 600 nm, thus requiring a high input of grinding energy.

[0010] The high input of energy for the manufacture of such a product is undesirable not only from an economic point of view, but above all from an environmental point of view. There is therefore a need for improved accelerator formulations with reduced energy consumption and an improved environmental footprint.

[0011] BRIEF DESCRIPTION OF THE FIGURES

[0012] FIG. 1 shows the heat flow in mW / gram of cement for the cement pastes with accelerator compositions 1, CO and C6 from the examples.

[0013] SUMMARY OF THE INVENTION

[0014] The invention relates to a method for producing a composition suitable as a setting and / or hardening accelerator for a hydraulic binder B2 comprising the following successive steps:

[0015] (i) mixing particles of a hydraulic binder Bl and water,

[0016] (ii) adding to the mixture obtained in step (i) a dispersant for dispersing the hydraulic binder Bl particles and an additive selected in the group consisting of alkanolamines, glycerol phosphate di sodium and mixtures thereof,

[0017] (iii) and mixing.

[0018] Advantageously, mixing step (iii) starts between 5 minutes and 30 minutes, preferably between 7.5 minutes and 20 minutes after the start of mixing the hydraulic binder Bl and water in step (i).

[0019] Advantageously, the weight ratio of water / hydraulic binder Bl in step (ii) is from 1 to 6, preferably from 2 to 5.

[0020] Advantageously, the hydraulic binder Bl is a Portland cement.

[0021] Advantageously, the dispersant is a composition comprising a water-soluble polymer, preferably a polycarboxylate, more preferably a polycarboxylate ether and / or polycarboxylate ester.

[0022] Advantageously, the additive in step (ii) is an alkanolamine selected in the group consisting of Triisopropanolamine (TIPA), Triethanolamine (TEA), Diethanolisopropanolamine (DEIP A) and mixtures thereof and that the additive is added in an amount ranging from 0.02 % to 0.3% expressed in weight of additive relative to the weight of binder B 1.

[0023] Advantageously, the additive in step (ii) is P-Glycerophosphate di sodium salt pentahydrate added in an amount ranging from 0.1% to 0.7% in weight of additive relative to the weight of hydraulic binder B 1.

[0024] Advantageously, mixing step (iii) is carried out using mixing energy less than 80 kW / h, preferentially less than 70 kW / h.

[0025] Advantageously, the duration of mixing step (iii) ranges from 36 hours to 60 hours, preferentially from 42 hours to 54 hours.

[0026] The invention also relates to a method for accelerating setting and / or hardening of a hydraulic binder B2 comprising the following successive steps:

[0027] (j) producing a setting and / or hardening accelerator composition by the method as described above;

[0028] (jj) adding the composition obtained in step (j) to a composition comprising the hydraulic binder B2;

[0029] (jjj) optionally adding concrete admixtures as specified in EN 934-2 :2009+Al:2012 ; (jjjj) mixing.

[0030] Advantageously, the accelerator composition is added in step (j) in an amount ranging from 0.5% to 10%, preferably 0.5 % to 5%, more preferably 1% to 5%, expressed in weight of accelerator composition relative to the weight of hydraulic binder B2.

[0031] The method for accelerating setting and / or hardening of a hydraulic binder B2 can comprise the addition of water before step (jjj).

[0032] The invention also relates to a setting and / or hardening accelerator composition obtainable by the method as described above. The invention also relates to a setting and / or hardening accelerator as described above for accelerating the setting and / or hardening of a hydraulic binder B2.

[0033] Other aspects of the invention are as described below.

[0034] DEFINITIONS

[0035] A hydraulic binder is a material which sets and hardens by hydration. Setting is the changeover from the liquid or paste state to the solid state. Setting is followed or accompanied by a hardening phenomenon whereby the material acquires mechanical properties. Hardening generally occurs on completion of setting, in particular for cement.

[0036] A cement is a hydraulic binder comprising a proportion of at least 50 % by weight of calcium oxide (CaO) and silicon dioxide (SiCh). The cement is preferably a Portland cement as defined in the standard NF-EN-197-1 of April 2012. The expression “Portland cement” is understood to mean, for example, according to the invention, a cement of CEM I, CEM II, CEM III, CEM IV or CEM V or CEM VI type according to the “Ciment” [Cement] Standard NF EN 197-1 of April 2012 and NF EN 197-5 of May 2021.

[0037] DETAILED DESCRIPTION

[0038] The inventors have developed a method for producing a composition suitable as a setting and / or hardening accelerator that meets the needs expressed.

[0039] The invention gives the possibility of manufacturing efficient seeds accelerator from a hydraulic binder without implementing high energy consuming steps, especially without the need for excessive use of high shearing energy to reduce the hydraulic binder particle size.

[0040] Method for producing a composition suitable as a setting and / or hardening accelerator

[0041] A first object of the invention is thus a method for producing a composition suitable as a setting and / or hardening accelerator for a hydraulic binder B2 comprising the following successive steps: (i) mixing particles of a hydraulic binder Bl and water,

[0042] (ii) adding to the mixture obtained in step (i) a dispersant for dispersing the hydraulic binder Bl particles and an additive selected from the group consisting of alkanolamines, glycerol phosphate di sodium and mixtures thereof,

[0043] (iii) and mixing.

[0044] The method is a method for producing a setting and / or hardening accelerator composition.

[0045] Step (i)

[0046] The hydraulic binder Bl can be Portland cement as defined above, cement with special properties (as defined in the DIN 1164 standard), white cement, calcium aluminate cement or high-alumina cement (as defined in the EN 14647 standard), calcium sulfoaluminate cement, and specialty cements, or mixtures thereof.

[0047] Advantageously, the hydraulic binder Bl is a Portland cement. The Portland cement can be a CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI and is preferably a CEMI cement.

[0048] The hydraulic binder B 1 is in the form of a powder, i.e. in particulate form. For the present purposes, the term “particle” or “particulate form” or “powder” refers in particular to solids with a diameter D50 above 1 pm and / or a D90 above 10 pm.

[0049] The hydraulic binder Bl particles may have a D50 from 5 pm to 20 pm and / or a D90 from 15 pm to 100 pm.

[0050] D90, also noted as Dv90, corresponds to the 90thcentile of the volume distribution of particle sizes, i.e. 90% of the volume consists of particles for which the size is less than D90 and 10% with a size greater than D90.

[0051] Also, D50, also noted as Dv50, corresponds to the 50thcentile of the volume distribution of particle sizes, i.e. 50% of the volume consists of particles for which the size is less than D50 and 50% with a size greater than D50.

[0052] D50 or D90 of a set of particles may generally be determined by laser particle size measurement for particles with a size of less than 800 pm. Step (ii)

[0053] The dispersant for dispersing the binder particles is advantageously a composition comprising a water-soluble polymer, which is preferably a polycarboxylate, more preferably a polycarboxylate ether and / or polycarboxylate ester.

[0054] The composition comprises the water-soluble polymer and a suitable water-miscible solvent, preferably water. The water-soluble polymer is preferably the sole component having the function of dispersant in the composition.

[0055] The water-soluble polymer content in the composition can vary from provider to provider. The skilled person knows how to adapt the content of dispersant added in step (ii) on a case-by-case basis to obtain the dispersing effect.

[0056] The water-soluble polymer can be a comb polymer comprising a polycarboxylate backbone with polyether side chains bound thereto. The side chains are in particular bound to the polycarboxylate backbone via ester, ether, imide and / or amide groups.

[0057] Advantageous comb polymers are, for example, copolymers of acrylic acid and / or maleic acid monomers and also monomers selected from among polyalkylene glycol vinyl ethers, polyalkylene glycol (meth)allyl ethers and polyalkylene glycol isoprenyl ethers. Copolymers of maleic acid or derivatives thereof, allyl ethers, in particular allyl polyethylene glycols, and vinyl acetate, for example, are particularly suitable.

[0058] For example, copolymers of maleic acid or derivatives thereof, allyl ethers, especially allyl-polyethylene glycols, and methacrylic acid are likewise suitable.

[0059] Preferably, the comb copolymer is a polycarboxylate ether. Polycarboxylate ethers are structurally more stable than polycarboxylate esters which can be saponified, especially at neutral or alkaline pH.

[0060] The additive used in step (ii) is selected in the group consisting of alkanolamines, glycerol phosphate di sodium and mixtures thereof.

[0061] Advantageously, the additive in step (ii) is an alkanolamine selected in the group consisting of Triisopropanolamine (TIPA), Triethanolamine (TEA), Diethanolisopropanolamine (DEIP A) and mixtures thereof and the additive is added in an amount ranging from 0.02% to 0.3% in weight of additive relative to the weight of hydraulic binder B 1.

[0062] Advantageously, the additive in step (ii) is glycerol phosphate di sodium.

[0063] Glycerol phosphate disodium (GPD) can be hydrated and is preferably a pentahydrate (GPD, 5H2O). Advantageously the GPD is P-Glycerophosphate disodium salt pentahydrate and P-Glycerophosphate di sodium salt pentahydrate is preferably added in an amount ranging from 0.1% to 0.7% in weight of additive relative to the weight of hydraulic binder B 1.

[0064] Advantageously, the weight ratio of water / hydraulic binder Bl in step (ii) is from 1 to 6, preferably from 2 to 5.

[0065] Water here refers to the water from step (i), the water coming from the dispersant and possibly some additional water.

[0066] Mixing step (iii)

[0067] Mixing step (iii) takes place with a temporal offset. Advantageously, mixing step (iii) starts between 5 minutes and 30 minutes, preferably between 7.5 minutes and 20 minutes after the start of mixing the hydraulic binder Bl and water in step (i).

[0068] In some embodiments, the dispersant and the additive are added in step (ii) with such a temporal offset and mixing step (iii) starts just after step (ii).

[0069] Examples of mixing methods that can be used for step (iii) are stirring or shaking. Suitable processes and apparatus for mixing are known to the skilled person. Suitable mixing apparatuses are, for example, stirred tanks, dynamic and static mixers, single-shaft stirring mechanisms, examples being stirring mechanisms that have scraper devices, especially those as paste stirrers, multishaft stirrers, solid mixers, and also mixing / kneading reactors. In the context of the invention, mixing step (iii) does not induce high shearing. Examples of devices inducing high shearing and thus not suitable to perform mixing step (iii) are bead mill, ball mill, ultrasound devices or rotor-stator (e.g. IKA Ultra-Turrax), high-speed stirrers or disk-stirrers.

[0070] Advantageously, mixing step (iii) is not a grinding nor a milling step.

[0071] Advantageously, mixing step (iii) does not significantly alter the particle size distribution of the hydraulic binder Bl, i.e., that the D50 of the binder particles is not substantially modified.

[0072] By ‘not substantially modified’ it has to be understood that the D50 of the hydraulic binder Bl particles does not decrease by more than 50%.

[0073] In some cases, the D50 of the hydraulic binder Bl particles can be reduced of more than 50% but the D50 of the binder particles after step (iii) remains higher than 1 pm, preferably higher than 5 pm, more preferably higher than 10 pm.

[0074] Advantageously, the D50 of the hydraulic binder Bl particles after step (iii) ranges from 5 pm to 15 pm and / or the D90 ranges from 10 pm and / or 50 pm.

[0075] Advantageously, the mixing step (iii) is carried out using a mixing energy of less than 80 kwh, preferentially less than 70kwh per metric ton of composition.

[0076] Advantageously, the method for producing a composition suitable as a setting and / or hardening accelerator does not comprise a step of grinding nor milling.

[0077] The hydraulic binder Bl is at least partially, in particular completely, hydrated at the end of step (iii). In this context, “hydration” means that the binder Bl has reacted in a hydration reaction to form solid hydrates or hydrate phases. Simple deposition of or envelopment / encapsulation / coating by molecules of the liquid medium, in particular water, to form a hydration shell is in the present context not considered to be hydration. Advantageously, the duration of mixing step (iii) ranges from 36 hours to 60 hours, preferentially from 42 hours to 54 hours.

[0078] In the prior art, the process to manufacture efficient setting / or hardening accelerator for hydraulic binders involves grinding step with high energy shearing to reduce the particle size of hydraulic binder particles well below 1 pm.

[0079] The process according to the invention involves the use of a dispersant and specific additives with a temporal offset for mixing step (iii). This process eliminates the need for a grinding step with high energy shearing to reduce the particle size of hydraulic binder particles. The process thus consumes much less energy.

[0080] Method for accelerating setting and / or hardening of a hydraulic binder B2 using a setting and / or hardening accelerator composition according to the invention

[0081] Another object of the invention is a method for accelerating setting and / or hardening of a hydraulic binder B2 comprising the following successive steps:

[0082] (j) producing a setting and / or hardening accelerator composition by the method described above;

[0083] (jj) adding the composition obtained in step (j) to a composition comprising the hydraulic binder B2;

[0084] (jjj) optionally adding concrete admixtures as specified in EN 934-2 :2009+Al:2012 (jjjj) mixing.

[0085] The hydraulic binder B2 may be any hydraulic binder, as described above for the hydraulic binder B 1.

[0086] The composition comprising the hydraulic binder B2 in step (jj) can be any composition comprising such a said binder. It can be a cement composition, a composition for concrete, a composition for mortar, a composition for grout or a composition for a foam.

[0087] Advantageously, the accelerator composition is added in step (jj) in an amount ranging from 0.5% to 10%, preferably from 0.5% to 5%, more preferably from 1% to 5%, expressed in weight of accelerator composition relative to the weight of hydraulic binder B2.

[0088] Some water may be added before step (jjj) so that the water / hydraulic binder B2 weight ratio ranges from 0.2 to 1.0.

[0089] Concrete admixtures as specified in EN 934-2 :2009+Al:2012 may be further added in the optional step (jjj). Such concrete admixtures can be water retaining admixtures, air entraining admixtures, set accelerating admixtures, hardening accelerating admixtures, set retarding admixtures, water resisting admixtures or viscosity modifying admixture.

[0090] In particular, the concrete admixture added in step (jjj) can be an additional setting and / or hardening accelerator that is compatible with the setting and / or hardening accelerator used in step (j).

[0091] Accordingly, the setting and / or hardening accelerators can thus be combined. As a result, the accelerating action can be increased and / or matched in the best possible way to specific requirements where necessary for specific applications.

[0092] In principle, many substances known to a person skilled in the art can be used here. The additional setting and / or hardening accelerator can be: a) one or more amino alcohols and / or salts thereof b) one or more alkali metal nitrates and / or alkaline earth metal nitrates c) one or more alkali metal nitrates and / or alkaline earth metal nitrites d) one or more alkali metal thiocyanates and / or alkaline earth metal thiocyanates e) one or more a-hydroxy carboxylic acids f) one or more alkali metal halides and / or alkaline earth metal halides g) one or more aluminum salts h) one or more alkali metal hydroxides and / or alkaline earth metal hydroxides i) one or more alkali metal carbonates.

[0093] Another object of the invention is a setting and / or hardening accelerator composition obtainable by the method described above.

[0094] Another object of the invention is the use of a setting and / or hardening accelerator composition as described above for accelerating the setting and / or hardening of a hydraulic binder B2.

[0095] Methods

[0096] Laser Grain Particle Size Measurement Method

[0097] The grain particle size curves of the different powders are obtained with a laser Malvern MS2000 granulometer. The measurement is carried out in a suitable medium (for example, in an aqueous medium); the size of the particles should be comprised from 0.02 pm to 22 mm. The light source consists of a red He — Ne laser (632 nm) and a blue diode (466 nm). The optical model is the Fraunhofer one, the computation matrix is of the polydisperse type.

[0098] A measurement of background noise is first of all carried out with a pump rate of 2, 000 rpm, a stirring rate of 800 rpm and a measurement of noise over 10 s, in the absence of ultrasonic waves. It is then checked that the light intensity of the laser is at least equal to 80%, and that a decreasing exponential curve is obtained for the background noise. If this is not the case, the lenses of the cell have to be cleaned.

[0099] A first measurement is then carried out on the sample with the following parameters: pump rate of 2, 000 rpm, stirring rate of 800 rpm, absence of ultrasonic waves, obscuration limit between 10 and 20%. The sample is introduced in order to have an obscuration slightly greater than 10%. After stabilization of the obscuration, the measurement is carried out with a duration between the immersion and the measurement set to 10 s. The measurement’s duration is 30 s (30,000 analyzed diffraction images). In the obtained granulogram, the fact that a portion of the population of the powder may be agglomerated should be taken into account.

[0100] Next a second measurement (without emptying the tank) is then carried out with ultrasonic waves. The pump rate is brought to 2, 500 rpm, the stirring to 1, 000 rpm, the ultrasonic waves are 100% emitted (30 Watts). This rate is maintained for 3 minutes, and then one returns to the initial parameters: pump rate 2,000 rpm, stirrer rate of 800 rpm, absence of ultrasonic waves. After 10 s (for removing the possible air bubbles), a measurement is made for 30 s (30,000 analyzed images). This second measurement corresponds to a powder de-agglomerated by ultrasonic dispersion.

[0101] Each measurement is repeated at least twice in order to check the stability of the result. The apparatus is calibrated before each working session by means of a standard sample (silica CIO Sifraco) the particle size curve of which is known. All the measurements shown in the description and the announced ranges correspond to the values obtained with ultrasonic waves.

[0102] EXAMPLES

[0103] 1. Accelerator composition

[0104] 1.1. Materials :

[0105] Dispersant:

[0106] Glenium ACE 456 from MBCC: 30% solids in water

[0107] Additives:

[0108] P-Glycerophosphate disodium salt pentahydrate (GPD.5H2O), CAS No.: 13408- 09-8 : 10% solids in water

[0109] Glycerol

[0110] Alkanolamines: o Triisopropanolamine (TIP A): 1% solids in water o Diethanolisopropanolamine (DEIP A): 1% solids in water o Triethanolamine (TEA): 1% solids in water

[0111] - NaSCN: solid form

[0112] X-Seed 100 from MBCC : suspension of nanoparticles of calcium silicate hydrate (CSH): around 20% solids

[0113] Portland cement

[0114] CEM-I 52, 5N from Vai d' Azergues (Lafarge France) named as VZ Portland cement

[0115] CEM-I 52, 5N from Obourg (Holcim Belgium)

[0116] 1.2. Preparation of accelerator composition

[0117] Accelerator compositions are prepared as follows:

[0118] Laboratory conditions at 20°C: In a 50 mL bottle, 15 g of demineralized water is added.

[0119] The necessary quantities of dispersant and additives are then added (when they are present from the start of the synthesis - see compositions in Tables 1 and 2), followed by the necessary quantity of Portland cement (7.5 g) as hydraulic binder Bl.

[0120] The Portland cement is added using a funnel, in order to add it gradually into the bottle. The bottle is then closed. This time is considered as tO.

[0121] The bottle is then shaken vigorously for 1 minute and placed on a roller shaker (45 rpm) (Supplier Wheaton-DWK Life Sciences).

[0122] In a delayed mode (t0+10 minutes), the necessary quantities of dispersant and additives are added (see compositions in Tables 1 and 2) to the 50 mL bottle.

[0123] The bottle is then shaken vigorously for 1 minute before being placed back to the roller turner.

[0124] The weight ratio of dispersant (as a liquid) / Portland cement ratio is equal to 1.

[0125] The weight ratio of dry dispersant / Portland cement ratio is equal to 0,3.

[0126] Tables 1 and 2 respectively provide the composition of accelerator compositions from VZ Portland cement and Obourg Portland cement.

[0127] The weight ratio of water / Portland cement is from 2 to 2.9 depending on the accelerator compositions.

[0128] The accelerator compositions are left to shake for 48h.

[0129] Compositions named ‘CX’ - C0-C13 - are comparative compositions, not according to the invention.

[0130] Compositions named ‘ Y’ - 1-7 - are compositions according to the invention.

[0131] 2. Accelerating performances

[0132] The performances of the accelerator compositions described above are evaluated as follows.

[0133] 2.1. Test conditions

[0134] Laboratory test conditions at 20°C:

[0135] For each accelerator composition: in a Kenwood mixer bowl (Kenwood KM201), completely empty the 50 mL bottle containing the accelerator composition described above, which has been left to shake for 48 hours. This bottle is rinsed several times with some tap water to wash away all the remaining materials. Complete with tap water to reach a water / hydraulic binder B2 weight ratio of 0.35, taking into account the water provided by the accelerator composition (for the calculation, the assumption is made that 1g of hydraulic binder Bl has reacted with 0,4g of water to form hydrates).

[0136] Place the Kenwood bowl onto the mixer.

[0137] 637.5 g of CEM I 52.5N SPLC cement from Saint-Pierre La Cour as hydraulic binder B2 is introduced in the mixer bowl. The ratio (hydrated hydraulic binder Bl + dry dispersant) / hydraulic binder B2 is equal to 0.02.

[0138] Mixing procedure:

[0139] • Mixing at speed 1 for 15 seconds

[0140] • Stop mixing for 15 seconds to scrape the sides and bottom of the bowl with the paddle

[0141] • Mixing at speed 6 for 30 seconds

[0142] • Stop mixing for 15 seconds to scrape the sides and bottom of the bowl with the paddle

[0143] • Mixing at speed 6 for 45 seconds

[0144] A cement paste is obtained at the end of the mixing step.

[0145] 2.2. Calorimetry

[0146] To estimate the acceleration performance of the accelerator compositions in the cement pastes, measurements were carried out by isothermal heat flow calorimetry.

[0147] Immediately after mixing, 7.5 g of each cement paste are placed in a calorimetry cell which is inserted into a calorimeter (Calmetrix LCalFlex).

[0148] The evolution of the heat flow is measured over time. In particular, the instantaneous heat flow at 3 hours (mW / g cement) is recorded.

[0149] Figure 1 illustrates the evolution of heat flow for: a reference cement paste (with an accelerator composition CO comprising no dispersant and no additive); a cement paste manufactured from an accelerator composition (C6) comprising a dispersant and an additive but not according to the invention: the kinetics of cement hydration is not accelerated (heat flow at 3 hours below heat flow for the reference cement paste); a cement paste manufactured from an accelerator composition (1) comprising a dispersant and an additive according to the invention: in that case, the instantaneous heat flow at 3 hours is increased compared to the reference cement paste showing that cement hydration is accelerated.

[0150] 2.3. Results

[0151] Tables 1 and 2 respectively summarize the results obtained for the accelerator compositions from VZ Portland cement and Obourg Portland cement.

[0152] Table 1 : accelerator compositions from CEM I 52.5N Portland cement from VZ: composition and results (measurements of instantaneous flow at 3h for the cement pastes in the calorimetry test) Table 2: accelerator compositions from CEM I 52.5N Portland cement from Obourg: composition and results (measurements of instantaneous flow at 3 hours for the cement pastes in the calorimetry test)

[0153] The results demonstrate that the timing for addition of dispersant and additive further improves the performance of the accelerator composition. When the dispersant is added at tO (comparative examples C11-C13, Cl, C2) the desired instantaneous flow of the reference cannot be reached irrespectively if additional additives are used or not. Furthermore, the addition of additive at tO and subsequent addition of dispersant at t+10 min fails to meet the desired flow rates (comparative examples C4, C6). Surprisingly, it was found that the combined addition of dispersant and suitable additive at t+10 min significantly increases the flow rate. It was found that the addition of a suitable alkanolamine (e.g., TIPA, TEA or DEIPA) or GPD., 5H2O (Glycerol Phosphate Disodium) significantly increases the flow rate (examples 1-7 according to the invention). As disclosed in the examples, none of the alternative additives (NaSCN, Glycerol, or Xseed-100) reach the performance of the compositions manufactured using alkanolamines or GPD, 5H2O despite following the same two-step process (comparative examples C5, C7-C9).

Claims

CLAIMS1. A method for producing a setting and / or hardening accelerator composition for a hydraulic binder B2 comprising the following successive steps:(i) mixing particles of a hydraulic binder Bl and water,(ii) adding to the mixture obtained in step (i) a dispersant for dispersing the hydraulic binder Bl particles and an additive selected in the group consisting of alkanolamines, glycerol phosphate disodium and mixtures thereof,(iii) and mixing.

2. The method according to claim 1, characterized in that mixing step (iii) starts between 5 minutes and 30 minutes, preferably between 7.5 minutes and 20 minutes after the start of mixing the hydraulic binder Bl and water in step (i).

3. The method according to claim 1 or claim 2, characterized in that the weight ratio of water / hydraulic binder Bl in step (ii) is from 1 to 6, preferably from 2 to 5.

4. The method according to any one of the preceding claims, characterized in that the hydraulic binder Bl is a Portland cement.

5. The method according to any one of the preceding claims, characterized in that the dispersant is a composition comprising a water-soluble polymer, preferably a polycarboxylate, more preferably a polycarboxylate ether and / or polycarboxylate ester.

6. The method according to any one of the preceding claims, characterized in that the additive in step (ii) is an alkanolamine selected in the group consisting of Triisopropanolamine (TIPA), Triethanolamine (TEA),Diethanolisopropanolamine (DEIPA) and mixtures thereof and that the additive isadded in an amount ranging from 0.02 % to 0.3% expressed in weight of additive relative to the weight of binder B 1.

7. The method according to any one of claims 1 to 5, characterized in that the additive in step (ii) is P-Glycerophosphate di sodium salt pentahydrate added in an amount ranging from 0.1% to 0.7% in weight of additive relative to the weight of hydraulic binder B 1.

8. The method according to any one of the preceding claims, characterized in that mixing step (iii) is carried out using mixing energy less than 80 kW / h, preferentially less than 70 kW / h.

9. The method according to any one of the preceding claims, characterized in that the duration of mixing step (iii) ranges from 36 hours to 60 hours, preferentially from 42 hours to 54 hours.

10. Method for accelerating setting and / or hardening of a hydraulic binder B2 comprising the following successive steps:(j) producing a setting and / or hardening accelerator composition by the method according to any one of the preceding claims;(jj) adding the composition obtained in step (j) to a composition comprising the hydraulic binder B2;(jjj) optionally adding concrete admixtures as specified in EN 934- 2:2009+Al:2012 ;(jjjj) mixing.

11. The method according to claim 10, characterized in that the accelerator composition is added in step (j) in an amount ranging from 0.5% to 10%, expressed in weight of accelerator composition relative to the weight of hydraulic binder B2.

12. The method according to claim 10 or claim 11, characterized in that it comprises the addition of water before step (jjj).

13. Setting and / or hardening accelerator composition obtainable by the method according to any one of claims 1 to 9.

14. Use of a setting and / or hardening accelerator composition according to claim 13 for accelerating the setting and / or hardening of a hydraulic binder B2.

Images