BG111998A - Accelerator of the thickening and hardening of hydraulic solutions and cement compositions containing this accelerator - Google Patents

Abstract

The invention relates to an accelerator of the thickening and hardening of hydraulic solutions containing the following proportions by weight: from 25 to 35% of at least one sulpho-aluminum clinker, from 45 to 55% of at least one source of sulphates with solubility above 4 g/l-1 in water at 20?C, and from 10 to 20% of at least one source of sulphates with solubility under 4 g/l-1 in water at 20?C, whereby the clinker contains mineralogical compounds of the calcium aluminates type. The cement composition which includes this accelerator of the thickening and hardening, can be used at temperatures from 5 to 35?C, and can be used for the preparation of shotcrete or mortar for sealing joints, or for surfacing with improved mechanical resistance to pressure.

Description

ACCELERATOR OF THICKENING AND HARDENING OF HYDRAULIC SOLUTIONS AND CEMENT COMPOSITIONS CONTAINING THIS ACCELERATOR.

Field of technology

The present invention relates to an accelerator for compaction and hardening of hydraulic mortars, cement compositions comprising an accelerator for compaction and hardening of hydraulic mortars, and to their application in particular to shotcrete concrete or mortars intended for sealing joints or leveling. .

BACKGROUND OF THE INVENTION

Shotcrete is a product that is transported at a very high speed by compressed air through a pipe and sprayed on a surface or some substrate to which it adheres. The shotcrete compositions allow the application of a layer of hydraulic mortar on substrates that are inclined, convex or concave. An example of this is generally the walls of underground galleries or tunnels. These compositions must be liquid enough to be sprayed, but at the same time sufficiently resistant to adhere to the walls on which they will be sprayed without flowing over them.

In addition to these limitations, specialists must also take into account other factors, such as ambient temperature, which may vary depending on the location and application of the shotcrete. The temperature of the environment has a strong influence on the durability of concrete in the short and long term. If the environment is very cold, the concrete will not have the necessary mechanical stability in the short term. If the environment is very warm, the long-term mechanical resistance will be lower than expected under normal conditions.

Mortars for filling joints and leveling surfaces allow the fixing of anchor reinforcement in activities with reinforced concrete due to their very high resistance to tearing. They can be used in any construction configuration (ceiling, walls and floor). They are available as a pre-prepared mixture (a mixture of binders, sand and additives) and are used after manual or mechanical mixing with water. Unlike grout filling solutions, surface leveling mortars are liquid, providing easy filling of irregularities, such as those obtained from heavy or vibrating machines, machine tools, centrifuges, forming a homogeneous homogeneous and stable base.

In these applications (joint filling and leveling), stability in the initial period is mandatory to provide the necessary working conditions in the short term. This resistance can be achieved by using, as binders, Portland Class R cement (fast-curing); however, sometimes very high resistance to mechanical impact is required in the short term and it can only be achieved by using special types of cement - aluminum type or sulfo-aluminum type. These special binders also have the advantage that, when carefully prepared, they cause less shrinkage, a quality which is particularly useful in this type of application.

In addition, the ambient temperature also affects the mechanical stability of the mortar for filling joints and leveling surfaces in the short and long term.

It is important for those skilled in the art to have a composition that remains in a liquid state and can be used for a longer or shorter period of time, but at the same time to change into a healthier consistency and to thicken and harden faster as soon as it has been applied. The latter condition can be achieved by adding a thickening accelerator and hardening the composition. Compression and curing accelerators known to those skilled in the art are, for example, nitrate salts, chlorine salts, alkanol-amines, formaldehyde, thiocyanates, colloidal suspensions of silica, alkaline aluminates.

However, these compression and curing accelerators can affect the mechanical properties of short-term stability and even prevent the achievement of a sufficiently high mechanical resistance, especially at low temperatures, such as at temperatures below 10 ° C and even below 5 ° C.

The use of cements or aluminum or sulpho-aluminum clinkers as accelerators of thickening and hardening is also known to those skilled in the art.

The use, for example, of accelerators for the thickening and hardening of, for example, cements or aluminum or sulpho-aluminum clinkers is a delicate matter. Indeed, any change or error in dosing when mixing this type of accelerator with hydraulic solution (Portland cement) can, under the influence of ambient temperature, inhibit or accelerate the hydration reactions of the binder, thus making it difficult to manage. the mechanical behavior of the solder binder / hydraulic element / accelerator.

In general, these compression and hardening accelerators are known for their effects at normal temperatures (around 20 ° C), but are not applicable in 'more extreme' temperatures.

Technical essence of the invention

There is a need for specialists in the field who use compositions of hydraulic solutions at high and low temperatures (from + 5 ° C to + 35 ° C), and their expectations for achieving stability in the short term (above 0.4 MPa, for 3 hours; over 30 MPa, for 28 days), to have an accelerator of thickening and hardening so as not to put in a risky situation the integrity of the structure in the long run.

Therefore, one of the objects of the present invention is to provide an accelerator for the thickening and hardening of hydraulic solutions, which overcomes the inconveniences described above.

Another object of the present invention is to provide a compaction and curing accelerator for cementitious compositions intended for use in mortars for leveling surfaces or for shotcrete, and in particular those suitable for use at low or high temperatures in which high short-term shrinkage resistance (Rc) is required while maintaining good long-term mechanical shrinkage resistance (Rc).

The present invention achieves these various objects thanks to the accelerator of compaction and hardening of hydraulic solutions containing the following mass ratios:

- from 25 to 35% of at least one sulpho-aluminum clinker,

- from 45 to 55% at least one source of sulphates with a solubility higher than 4 g / l. in water at 20 ° C, and

- from 10 to 20% at least one source of sulphates with solubility below 4 g / l. at 20 ° C, the clinker containing mineralogical compounds of the calcium aluminate type.

For the purposes of the present invention, the solubility is read in pure water and at a temperature of 20 ° C.

Mineralogical constituents are designated by their common name, followed by the cement nomenclature. The primary compounds are represented in the cement nomenclature by: C for CaO, S for SiO, A for AI2O3, $ for SO3, H for H2O; this nomenclature is used throughout the text.

Within the scope of the present invention, the thickening and hardening accelerator of the hydraulic mortars is intended to be added to a hydraulic mortar for the preparation of a cement mixture.

"Hydraulic solution" means a hydraulic solution within the meaning of standard EN 197-1, and in particular the definition in paragraph 4: "inorganic finely ground material which, when mixed with water, forms a product in the form of a slurry which thickens and hardens as a result of interactions and hydration, and which, after hardening, remains stable even under water. '

The term "finely ground" means a particle size of about 2500 to 5000 cm ² / g.

The term "calcium aluminate type mineralogical compound" means any mineralogical phase obtained by mixing alumina (chemical formula AI2O3 or "A" in the cement nomenclature) and calcium oxide (chemical formula CaO or "C" in nomenclature of cement) with other types of inorganic substances such as sulphates (with chemical formula SO3, or "$" in the nomenclature of cement), iron oxide (with chemical formula BegOz or "F" in the nomenclature of cement) or fluorine.

The sulfo-aluminum clinker can be mixed with aluminum clinker, with sulfocalcium silicate clinker, and / or fluorine aluminum clinker.

The term "sulpho-aluminum" means any material obtained by heating to a temperature in the range of 900 ° C to 1350 ° C of mixtures containing at least one source of lime, at least one source of alumina and at least one source of sulfates. The sulfo-aluminum clinker, which is part of the accelerator for hardening and hardening of hydraulic solutions according to the present invention, contains Yeelimite (with chemical formula 4CaO.3Al2O3.SiO3 or C4AZ $ according to the cement nomenclature) in amounts over 30% by weight, preferably from 50 to 70% by weight. The content of Belite (with chemical formula (CaO.SiO2 or C2S according to the cement nomenclature) of the sulfo-aluminum clinker is preferably such that the weight ratio of Yeelimite to Belite is greater than or equal to 1.5.

The term 'sulpho-belite' means any material obtained by heating to a temperature in the range of 900 ° C to 1350 ° C of mixtures containing at least one source of sulphates. The sulpho-belite clinker, which may be part of the accelerator for hardening and hardening of hydraulic solutions according to the present invention, contains Yeelimite (with chemical formula 4CaO.3Al2O3.SiO3 or C4AZ $ according to the cement nomenclature) in an amount exceeding 30% by weight, preferably in the range of 50 to 60% by weight. The Belite content of this sulfo-belite clinker is preferably above 20% by weight, so that the Yeelimite to Belite weight ratio is below 1.5.

The term "fluoroaluminum" means a product obtained by heating at high temperature (usually 1200 ° C-1350 ° C) of crude PORTLAND containing CaF ₂ fluoride in such quantities that the resulting clinker contains at least 15% calcium fluorine aluminate SpAuCaBg.

The degree of Blaine grinding in these sulfo-aluminum, sulfo-belite or fluoro-aluminum clinkers is in the range of 2500 to 5000 cm ² / g.

It is recommended that these calcium aluminate-type mineralogical compounds contained in the clinker be selected from the group of Yeelimite (C4AZ $), Mayenite (C12A7), calcium mono aluminate (CA) p tetra calcium aluminum ferrite (C4AF), aluminate (C3A), or a combination of several of these compounds, most preferably a combination of Yeelimite and one or more mineralogical compounds such as calcium aluminates.

Suitably, the total weight of these calcium aluminate-type mineralogical compounds in the clinker comprises more than 30% by weight of the total weight of the clinker, and in particular more than 50% by weight, i. the clinker according to the present invention comprises mineral phases of the aluminate type, and the sum of these phases constitutes at least half of the total mass of the clinker.

In a preferred embodiment, the calcium aluminate-type mineralogical compound forms the major part in the mixture of these calcium aluminate-type mineralogical compounds contained in the clinker and comprises more than 30% by weight of the total weight of the clinker, in particular more than 50% by weight of the clinker. %. Especially the main mineralogical phase of the aluminate type is Yeelimite (C4AZ $).

The term 'source of sulphates' means a substance obtained by dissolving sulphate ions. The most suitable sources of sulphates are sulphates |> 1> 1ГЙП1ГЙП.Ч »

salts, gypsum, sludge or other industrial waste products rich in sulphates (such as phosphorus gypsum, titanium gypsum). Sources of sulfates can also be used in mixtures of several sources. These products are rarely found in satisfactory purity in industrial quantities and this leads to their restrictive use due to the high cost. Therefore, it is necessary to look for options for working with mixtures containing impurities. In this case, specialists should adapt the required quantities of sulphate sources taking into account the required number of sulphate moles (expressed in SO3 "$" according to the cement nomenclature).

In the present invention, taking into account the solubility of the sulphates, the solubility of the sulphate ions contained is taken into account. In other words, in order to determine the solubility of the source of sulphates which are not in the pure state, the solubility of the main constituent of sulphate ions constituting that source of sulphates is taken into account.

It has been found that two sources of sulphates need to be present in order to obtain the desired strength characteristics of the cementitious compositions.

In particular, it has been found that each of the types of sulfate sources is likely to play an important role in the various stages of hydrate formation.

The presence of only one source of sulfates with a solubility of more than 4 g ^{l -1} ensures the formation of etringitis, which contributes to the stability of the material in the short term. Etringite is formed from the aluminate phases obtained simultaneously from both the hydraulic solution and the clinker.

Due to the presence of at least one source of sulphates with a solubility above 4rp.n '', it is possible for the water of the mixture to contain sufficient sulphate ions from which to form etringite, depending on the phases present.

It is important to create such conditions that hydrated calcium mono sulfo-aluminates do not form (AFm or C3AC-H12 according to the cement nomenclature). Indeed, sulfate deficiency leads to the formation of hydrated calcium mono sulfo-aluminate by the decomposition of etringite. This hydrated calcium mono sulfo-aluminate is very unstable and does not allow controlling the stability of the cement matrix. In addition, the presence of sources of sulphates in solution in water after the curing step will cause a reaction of formation of ettringite from the hydrated calcium mono sulpho 6 '| B1 || CC | T il | i | -1 | l C aluminate, which is called delayed etringitis. The formation of delayed etringitis is accompanied by swelling and can cause expansion, cracking and even explosion of the structure.

The presence of at least one source of sulphates, the solubility of which is less than ⁴ g, l 4 creates conditions for continuous release of sulphates within the cement matrix during maturation. This, in particular, makes it possible for the hydration reactions to take place in the long term and thus not alter the material which is formed rapidly at the beginning of the thickening (for example by converting etringite to hydrated calcium mono sulpho-aluminate).

Typically, calcium sulfates, especially gypsum or anhydrite, are added to Portland-type clinker during its production to produce a hydraulic solution. For example, the addition of gypsum in amounts of 3 to 8 5 (in mass ratios, pure gypsum is added) is carried out to regulate the compaction and in particular to prevent the phenomena of sharp compaction of Portland type cement.

Experimental studies have shown that the source of sulfates ground with Portland clinker does not allow it to create problems in achieving sufficient mechanical resistance in the short and long term, over a large temperature range (see comparative examples below).

It is recommended that at least one source of sulphates, the solubility of which is below Chg. L ' ^1, be optionally of gypsum (CaSO4.2H2O), anhydrite (CaBOD) or a mixture thereof. In one embodiment, the solubility of gypsum is 2.4 g / ^l and that of anhydrite is 2.1 g of ^{l -1} in pure water at 20 ° C.

It is possible that the clinker contains calcium sulphates with a solubility below 4 g l ' ¹ (sulphate residues), as these sulphate residues are always in concentrations below 10% by weight, and very often below 5% by weight, and thus are obtained by heating raw cement. This residual calcium sulphate content is not sufficient for the practice of the present invention. It is necessary to add another source of sulphate with solubility below 4GR.L ' ¹ to the aqua and any residual sulphate content.

Suitably at least one source of sulphates which has a solubility of more than 4 g. L ' ¹ is selected from, for example, aluminum sulphate dodeca and octadeca hydrate (Ca3OD.HN3O) or a mixture thereof. In one exemplary embodiment, the solubility of ferrous sulphate 7.H 2 O is 30 g, ^{1 l} , the solubility of aluminum sulphate I4-I6. H2O is

364 g l and the solubility of the semi-hydrate (gypsum) should be 8.5 g l in clean water at a temperature of 20 ° С.

The characteristics by which the two sources of sulphates can be distinguished are, in practice, the dissolution kinetics. However, this characteristic is difficult to determine a priori, as it depends on many factors and parameters. Indeed, it must be determined experimentally for each sulphate depending on numerous conditions such as: temperature, salinity of the medium, nature of the concentration of available ions), pH and others. Other characteristics influence the manner and importance of the kinetics of salting, such as the degree of grinding of the source of sulfates, the degree of crystallization, etc. In practice, it is more convenient to monitor the solubility of substances in water at a certain temperature. These characteristics are well known to those skilled in the art (CRC Handbook of Chemistry and Physics (92nd edition), William M. Haynes, Editions & CRC Press / | Taylor and Francis).

It has been found that solubility makes it possible to predict the dissolution kinetics of a particular substance without resorting to lengthy experiments. Of course, prediction errors are possible, but this criterion has the advantage of being simple and easy to implement, and it can lead to an initial choice, which can then be further developed with more precise dissolution kinetics tests if necessary.

The present invention can be practiced by combining several clinkers. For simplicity and accessibility, however, it is preferred that the embodiment of the present invention be with a single clinker (sulfo-aluminum clinker) containing mineralogical compounds such as calcium aluminates. It is most suitable for the accelerator of thickening and hardening of the hydraulic solutions to cover only one clinker.

It is very suitable for the accelerator of the thickening and hardening of hydraulic solutions to contain a single source of sulphates which have a solubility of more than 4rp№.

Further preferably, the accelerator setting and hardening of hydraulic solutions contain a single source of sulphates, having a solubility below Fgr.l ^-1.

According to a preferred embodiment of the present invention, the thickening and hardening accelerator of hydraulic solutions comprises one

a single clinker (sulfo-aluminum clinker), a single source of sulphates with a solubility of more than 4 g. ^{l '1,} and a single source of sulphates with a solubility of POD4GR.L' ¹ .

It will be apparent to those skilled in the art that the simplest embodiment of the present invention consists in mixing three sources, each of which corresponds to a particular clinker and two sulfates, to obtain a three-component mixture for accelerator for thickening and hardening of hydraulic solutions according to the present invention. However, embodiments of the present invention with more complex mixtures of one, two or three sources are also possible, i. consisting of a mixture of components.

The present invention differs from the compositions that exist in the prior art in the "over-sulfation" of cementitious compositions. Whatever the content of sulphates with a solubility of less than 4 g of L ¹ in the hydraulic solutions to which a compaction and curing accelerator is added, an additional amount of sulphates with a solubility of less than 4 g of l '' is added in the practice of the present invention.

Therefore, the composition according to the present invention is in no way a simple mixture of a hydraulic solution (for example Portland cement) with one clinker (sulpho-aluminum clinker) and one source of sulphates which has a solubility of more than 4 g. for example aluminum sulphate), as even the hydraulic solution itself or the clinker will contain significant amounts from the sulphate source, which has a solubility of less than ⁴ g.

In particular, the accelerator for the thickening and hardening of hydraulic solutions is characterized by a ratio of more than 5% of this source of sulphates with a solubility of less than 4 g, the weight of the source of the sulphate with a solubility below Dgr .l ' ¹ and this amount may be contained in the clinker and may be obtained by heating the crude cement mixture.

The content of calcium sulphates in hydraulic solutions and clinkers is different for each product and is provided by the manufacturers. When such data are lacking or there is doubt as to the accuracy of the content, these values can be determined, for example, by X-diffraction analysis to quantify the phases by the Rietveld method.

In particular, this accelerator for the compaction and hardening of hydraulic solutions is characterized by a ratio of more than 5% of this source of sulphates with

solubility below 4rp№ and at any amount of sulphate source with a solubility below 4g.l ^-1 which may be contained in the hydraulic solution.

An advantage of the accelerator for hardening and hardening of hydraulic solutions according to the present invention is the molar ratio between the source of sulphates with solubility below Dgr.l ' ¹ and mineralogical compounds of the type of calcium aluminates, which should be from 0.3 to 55, preferably from 0.4 to 12.

It is also advantageous for the accelerator of the thickening and hardening of hydraulic solutions, the molar ratio between the source of sulphates with a solubility of less than 4 g / l and the mineralogical compounds of the type of calcium aluminates to be from 0.15 to 27, preferably from 0 , 3 to 10.

Studies have shown that the molar ratios described above between:

- on the one hand, the sources of sulphates with a solubility below 4rp ^ ^q , including those contained in the clinker, and the content of mineralogical compounds of the type of calcium aluminates contained in the clinker, and

- on the other hand, the sources of sulphates with solubility over 4 g ^{l -1} and the content of mineralogical compounds of the type of calcium aluminates contained in the clinker allow to obtain high values for mechanical resistance in the short and long term in a wide temperature range within from about + 5 ° C to 35 ° C.

It is important to note that these molar ratios refer to the accelerator of the thickening and hardening of hydraulic solutions, and not to the cement composition containing this accelerator. In other words, the amount of the sulphate source with a solubility below or above 4 g, which may be present in the hydraulic solution, does not affect the molar ratios quoted above.

It is appropriate that the molar ratio between the source of sulphates with a solubility of less than 4 g and the mineralogical compounds of the calcium aluminate type be in the range from 1.5 to 12.

It is recommended that the molar ratio between the source of sulphates with a solubility above 4 g / l and the mineralogical compounds of the calcium aluminates type be in the range from 1.8 to 8.

Even more preferably, the thickening and curing accelerator of hydraulic solutions according to the present invention is characterized in that

- sulpho-aluminum clinker containing more than 30% by weight of Yeelimite, preferably from 50 to 70% by weight of Yeelimite, and

- the source of sulphates with a solubility of more than 4 g is aluminum sulphate, and

- the source of sulphates with solubility below 4 g ^{. l '!} to be gypsum or anhydrite.

The present invention also relates to a cementitious composition comprising a hydraulic mortar, the thickening and hardening accelerator described above and optionally water.

The cement composition according to the present invention may also contain, in addition to the accelerator of the thickening and hardening of hydraulic solutions, a hydraulic solution: fillers, additives, impurities, binders, auxiliaries or a combination thereof. The term "one" hydraulic solution is used in the present invention, but it will be apparent to those skilled in the art that the same function may have a combination of different known binders, such as two different Portland cements, without substantial to modify the features of the present invention.

By "filler" is meant finely ground inorganic material, 85% of which has an element diameter of less than 80 pm. Fillers are used to optimize compactness by filling cavities.

"Impurity" means finely ground inorganic material with or without pozzolanic action. The term "pozzolanic effect", in this case, means promoting the acquisition of mechanical resistance. The additives are generally finely ground and have a diameter of less than 400 pm, in particular less than 150 pm. The additives can be ground separately from the hydraulic solution or mixed in it.

The following can be cited as pozzolanic impurities and fillers: blast furnace slag, silica dust and smoke particles. Limestone and silicon fibers can be cited as fillers and impurities without pozzolanic action.

"Excipient" means a substance within the meaning of standard EN 206.1, and in particular the definition in paragraph 3.1.22: product added to concrete during the mixing process, in small quantities relative to the weight of the cement, for modification of the properties of fresh and hardened concrete.

'Admixture' means substances or materials which may be added to a cementitious composition but which are not impurities, fillers or excipients as described above. The following can be cited as an example of an additive: fibers whose function is the strengthening of the structure (metallic, organic, inorganic), oxides having a photocatalytic action (TYr), and the heavy particles allow the isolation of radiation (in particular from minerals, and in particular iron minerals), electrically conductive particles to protect structures from electromagnetic radiation by creating Faraday cells (such as graphite), thermally conductive particles (metals), phase change particles (PCM) : phase-changing materials) for calorific energy storage in the structure or light particles improving thermal and sound insulation (organic particles such as polystyrene or inorganic particles such as vermiculite, perlite, silico-aluminates or glass).

Preferably, the hydraulic solution is based on a Portland-type binder, optionally from the group consisting of CEM I, II, III, IV or V, preferably CEM I, more preferably CEM I PM ES. "PM ES" means a binder with a low content of three calcium aluminate (SZA), and in particular above 5%, according to standard NF P 15-317 and NF P 15-319.

It is recommended that the total amount of SO3 obtained from the source of sulphates with a solubility below 4 g / l ^_1 contained in the cement composition be well above 5% of the total weight of the cement composition.

According to a preferred embodiment, the cementitious composition according to the present invention contains a larger amount from the source of sulphates with a solubility below 4 g / l 'than the amount that can be obtained using the maximum permissible sulphation of a hydraulic solution according to standards. Standard EN 197-1 (paragraph 9.2.3) specifies quantities of SO3 in the range of 4 to 5% (by weight) depending on the type of cement.

In one embodiment of the present invention, the weight ratio between the compression and curing accelerator and the hydraulic solution is from 0.1 to 0.2; preferably from 0.14 to 0.18, and even more preferably from 0.15 to 0.17.

If the weight ratio is below 0.1, it is likely that stability is achieved in the short term, and at low temperatures this resistance is not sufficient.

If the weight ratio is above 0.2, then the stability is probably achieved in the long run and under conditions of high temperatures this stability is not sufficient.

Most preferably, the weight ratio between the compression accelerator and the hardening of hydraulic solutions is about 0.16.

It is recommended that the cementitious composition defined above be used in the temperature range of about 5 ° C to 35 ° C.

In a particular embodiment, the cement composition according to the present invention comprises, in addition to the thickening and hardening accelerator of hydraulic solutions, the hydraulic solution itself, one or more auxiliaries, in particular super-plasticizers, thickening retarders; also one or more auxiliaries optionally of plasticizers, thickening accelerators other than those according to the present invention (eg nitrates, thiocyanates and / or chlorides), other hardening accelerators other than those according to the present invention (especially alkaline carbonates), anti-shrinkage agents, anti-bubbling or foaming agents, impermeable substances (such as calcium stearate), anti-precipitation agents (in particular bentonites, attapulgites), inorganic or organic pigments, latexes (in particular styrene). butadiene copolymers or vinyl acetate vinyl compounds or vinyl acetate monomeric acrylic compounds) or rheology modifiers (in particular modified polysaccharides or unmodified polysaccharides preferably diutane resins, xanthan resins, body resins and velanic resins; preferably ether-starches or ether-celluloses).

The cementitious composition contains, in addition to the thickening and hardening accelerator of the hydraulic solution, an auxiliary super-plasticizer, in particular polycarboxylate.

The cementitious composition contains, in addition to the thickening and hardening accelerator of the hydraulic solution, a thickening retarder, in particular polycarboxylic acid, preferably tartaric acid or citric acid. Auxiliary retarders, paradoxically, are of interest in connection with the present invention, in particular in its application to wet shotcreting concretes. Indeed, with this type of application, it is necessary

precise control of the compression period to avoid compression of the binder mixture in the pumping and injection equipment and tools.

The present invention also relates to the use of the cementitious compositions described above, comprising the accelerator of the compaction and hardening of the hydraulic solution in concrete, in particular in shotcrete, mortar, in particular for compaction and leveling, screeds and plasters or cement mortars.

By "plaster" or "cement mortars" is meant material due to the addition of water to cement compositions according to the present invention. The difference between these two concepts lies in the difference in the weight ratio between water and cement, where if the ratio is below 0.35 the mixture is called cement mortar, when the ratio is above 0.35 the mixture is called plaster.

By "screed" is meant plaster or cement mortar to which very fine granules have been added, with a diameter of 150 pm to 1 pm (eg fillers).

"Mortar" means plaster or cement mortar to which fine granules have been added, i. granules with a diameter of 150 pm to 4 mm (such as sand) and possibly very fine granules.

By "concrete" is meant a mortar to which very large granules have been added, i. granules with a diameter of more than 4 mm.

Typically, concretes, mortars, plasters, screeds and cement mortars are excipients.

Shotcrete concrete and its applications are subject to standard NF P 95-102.

The mortars are defined in standard NF P 1504-6.

Leveling mortars are defined in standard NF P 18-821.

The present invention relates to the applications of the cementitious composition described above, a mixture of fine granules, large granules with a maximum diameter of less than 12 mm, optionally very fine granules, water, and optionally auxiliaries, for the preparation of shotcrete.

"Sand" means a mixture of granules consisting of very fine granules, or fine granules, or a combination of fine and very fine granules.

A distinction is made between compression accelerators and hardening accelerators. Compression accelerators act within a certain period of time (material strengthening time), while hardening accelerators act on the mechanical stability. Therefore, compression accelerators do not necessarily lead to high material stability in the short term. Within the scope of the present invention, it is appropriate to have both characteristics (thickening and hardening) available to achieve this effect.

It is preferable to use cementitious compositions, such as those defined above, characterized in that the shotcrete concrete has a compaction time of less than 5 minutes, in particular less than 1 minute, it is even more appropriate that the compaction time be instantaneous.

The compaction time of the trocret concrete achieved by the cement composition according to the present invention is almost instantaneous after the addition of the water, therefore the use of the shotcrete concrete according to the present invention is carried out by the dry method. It is also possible to apply the invention within shotcrete by the wet method, but this requires the addition of thickening retarders (e.g. citric acid or tartaric acid).

The dry and wet methods differ significantly when water is added. The dry spraying also differs in the absence of so-called stirring. The dry mixture is pre-homogenized and moved through a tube (through compressed air) to a nozzle, at the end of which water is added. The water flow rate can be adjusted to adjust the water content of the injected material. Pre-wetting within 5% (by weight) against the current is allowed to avoid inconveniences related to dust emissions during injection.

The present invention also relates successfully to the use of a cementitious composition described above in admixture with fine granules, water and possibly very fine granules, and optionally auxiliaries, for the preparation of a mortar for compacting and leveling surfaces.

The difference between mortar for leveling and compaction exists and consists in the consistency of the obtained material. The leveling mortar is characterized by a much more liquid consistency than that of compaction mortars; this higher flowability is achieved by increasing the water / powder ratio. The consistency of mortars is determined according to the provisions of standard NF EN 1015-3. If the spread of the shaking mass is more than 200 mm, then the mortar is classified as liquid (standard NF EN 1015-6, table 1). The construction mixture intended for leveling has a spread of over 200 mm. Conversely, the compaction construction mixture is spread below or equal to 200 mm.

As an example, a leveling compound with a setting time of approx. 1 to 4 hours can be prepared, which can be prepared from a cementitious composition containing from 0.1 to 1% by weight of a thickening retarding auxiliary according to the present invention. .

Also by way of example, a compaction construction mixture with a thickening time of from 1 to 2 hours approximately can be provided, which can be prepared from a cementitious composition containing from 0.1 to 1% by weight of a thickening retardant. according to the present invention.

We will quote from the numerous possible applications of mortars the following:

- sealing of beams, columns, acroters;

- sealing of doors, windows and auxiliary elements;

- compaction of urban facilities, signaling elements;

- compaction of inspection shafts on roads with heavy traffic with almost instantaneous restoration of traffic.

The use of thickening retardants is required in this type of application (compaction and leveling) in order to be able to apply the cement composition before its thickening.

It is suitable to use the cement composition according to the present invention in conditions of temperature ranges from 5 ° C to 35 ° C approximately.

The present invention also relates to concrete or a building mix containing the cementitious composition defined above and its use in conditions of temperature ranges of approximately 5 ° C to 35 ° C, characterized in that they have mechanical resistance. of shrinkage at 3 hours, which is above 0.4 MPa, in particular above 1 MPa, and more preferably above 2 MPa, and mechanical resistance to shrinkage at 28 days above 30 MPa.

The value of 0.4 MPa is noted within the scope of the present invention to show that the product has passed the thickening step and the level of sufficient hardening or sufficient structuring has been reached to overcome the leakage of the material. This material applied to the substrate is no longer subject to "processing".

I. Materials and methods

Standards

The definition of Portland clinker is given in European standard EN 197-1.

Control data on the mechanical properties of cements are obtained according to European standard EN 196, paragraphs 1 to 7.

1. Materials used

1.1. The granule

Two 0.8 mm granular mixtures from SOCLI were used; both materials are sieved and are in four particle size fractions or parts as shown in Table 1 (in% by weight):

Table 1

Wasselonne Cormeilles Sand 0 / 0.5 28.8 26.15 Sand 0.5 / 2.5 16.41 - Sand 0.5 / 1.25 - 20.51 Sand 2.5 / 4 21.88 - Sand 1.25 / 3.15 - 19.15 Gravillon 4/8 32.82 34.19

1.2. Cement / clinker

Portland cement

CEM I type 52.5 N PM ES HRC (low SZA content; standard NF P 15.317) produced by the plants of Beaucaire (Calcia), Gaurain (Calcia), St Vigor (Lafarge) were used. Their compositions are given in Table 2 (in% by weight).

Table 2

Factories C3S C2S C3A C4AF SO3 Beaucaire 75 10 2 14 2.3 Gaurain 55 28 2 12 2.7 St Vigor 55 26 0.5 14.5 2.5

Sulfo-aluminum clinker

Sulfo-aluminum clinker, sold under the trade name Alipre (Italcementi, Guardiaregia, Italy) was used in all embodiments below, except for example 9. The clinker contains about 60% by weight of Yeelmite (calcium sulfo-aluminate: C4AZ $).

Experimental sulfo-aluminum clinker with about 30% Yeelmite content was also used, but only in Example 9. This clinker was prepared in the laboratory by heating at high temperature a crude mixture of limestone, clay, bauxite and gypsum, which are mixtures of different oxides, in particular CaO, SiC> 2, Al2O3, ResO2, and SO3. The possibilities for preparing a crude mixture, depending on the mineralogical preconditions of the desired clinker, are well known to those skilled in the art (Special Inorganic, Ivan Older, 2000, CRC Press). The main mineralogical phases of these two sulfo-aluminum clinkers are given in Table 3 (in% by weight).

Table 3

С4АЗ $ C28 C $ C12A7 Alipre 64.2 10.4 2.9 2.4 Experimental clinker 31.6 29 3.2 9.8

1.3. Excipients

A thickening and hardening accelerator according to the present invention.

The composition for the thickening and curing accelerator includes aluminum sulphates (A1r (8O4) 3 to 16 H2O) (Meatusel), natural micronized anhydrite (calcium sulphate, Societe Mosellance anhydrite) and sulpho-aluminum clinker.

Compression accelerator according to the prior art

Powder compaction accelerator was used for shotcrete by dry method, commercially available from SICA (Sigunit 49AF).

Super-plasticizer vya

The super-plasticizer used is Melfix 2651 F (BASF). In this case it is a super-plasticizer from the group of polycarboxylates, which is in the form of a powder.

2. Method

2.1. Ingredient ratios

The granule

Several different dosages of sands and granules were studied as follows: 698, 713, 722, 726 kg. sand and granules for one ton of dry mix.

Portland type cement: Several different dosages of cement were used as follows: 240,250,280 kg. cement for one ton of dry mix.

Accelerator: The specified ratios between accelerator / cement are in parts by weight.

Super-plasticizer: some compositions also contain an over-plasticizer. Unless otherwise indicated, these compositions have dosages of 0.9% by weight of superplasticizer relative to cement.

Water: Two different dosages of water were used: E / C = 0.45 and 0.385

Portland water / cement weight ratio. These dosages correspond to the water / total powder ratios = 0.12 and 0.10. By total amount of powder is meant the total solid components of the cement composition, ie. Portland type cement, sulfo-aluminum clinker, sources of sulfate and granules (sand and gravel).

2.2. Execution

The experiments were performed under the following conditions:

1.8 kg is prepared. a mixture containing all the ingredients of the hardening accelerator, Portland cement and granules and / or sands.

This mixture is introduced into a mixer with a volume of 3 liters, stirred for 1 minute at low speed (140 rpm in epicycloidal mode (or planetary) drive of the stirring knife, at 1 revolution / second, to achieve good homogenizing the mixture.

The mixing vessel is tightly covered with a plastic lid, then stored for 24 hours under the conditions of the desired climatic environment (temperature, humidity).

Mix exactly 1.8 kg of the mixture with water at the desired temperature, mixing for 20 seconds at 280 rpm, in an epicycloidal mode for 2 rpm (high speed).

The mechanical stability tests are then carried out without any delay, as the compression begins very quickly.

2.3. Chemical and mineralogical analyzes

The analyzes of the different chemical compositions, in particular the different determinations of the SO2 values of the sulphate sources, are carried out by fluorescence X spectrometry (Magix spectrometer, Panalytical).

Mineralogical analyzes concerning the different phases of the clinkers or cement that make up this hydraulic solution are performed by X diffraction (DRX) in quantitative measurement of the mineralogical phases using the Rietveld method (XPERT, PRO, Panalytical, EVA and TOPAS programs).

2.4. Mechanical characteristics

Tests for mechanical resistance to bending and shrinkage, in accordance with standard EN196-1, and for density in the solidified state shall be carried out on test specimens of mortars (dimensions: 4 cm x 4 cm x 16 cm) at different temperatures:

- Samples are prepared at a temperature of 5 ° C and stored in an air environment at 5 ° C, at 90% relative humidity.

- Samples are prepared at a temperature of 20 ° C and stored in an air environment at 20 ° C, at 75% relative humidity.

- the samples are prepared at a temperature of 35 ° C and stored in an air environment at 35 ° C, at 90% relative humidity.

II. Results tswHaiMrwiww'iiii pp

The composition of the curing accelerator according to the present invention is presented in weight percentages of the three components: sulfo-aluminum clinker, source of sulfates with a solubility of more than 4 g l ' ¹ (aluminum sulfate) and source of sulfates with a solubility of less than 4 g. l ' ¹ (natural micronized anhydrite).

The amount of Portland cement and granules is in kg per ton of fresh concrete.

The indicated temperature is the temperature at which the test specimens are prepared and the measurements are performed.

Shrinkage resistance (Rc) is expressed in MPa, at three hours, 7 days and 28 days, from the start of mixing. The start of mixing corresponds to the moment of contact between the water and the powder, pre-mixed in the dry state.

EXAMPLES

From the compositions presented as Examples 1 to 9 (Tables 2 to 10), "functional" test specimens (measuring 4 x 4 x 16) were obtained, i. such exhibiting mechanical resistance above 0.4 MPa, for 3 hours, and over 30 MPa for 28 days at temperatures from + 5 ° C to + 35 ° C.

In the samples for the thickening and curing accelerator according to the present invention, containing, by weight, sulfo-aluminum clinker from 25 to 35%, the mechanical resistance to shrinkage (Rc) at 3 hours and at a temperature of 5 ° C is below 1.46 MPa.

The sulfo-aluminum clinker contains about 60% Yeelmite type C4AZ $ and approximately 3% C $ (in% by weight).

Example 1: Different ratios of sulfo-aluminum clinker / aluminum sulfate

Table 4

Composition № 1 2 3 11 Cement I CEM I 52.5 N PM ES “HRC” (Gaurain) 280 260 260 260 Wasselone type sand 698 698 698 698 Water / cement 0.45 0.45 0.45 0.45 Accelerator / cement ratio 0.16 0.16 0.16 0.16 Sulfo-aluminum clinker (%) 55 25 35 65 Aluminum sulfate (%) 25 55 45 15 Anhydrite (%) 20 20 20 20

C $ / C4Az $ (molar ratios) 2.36 5.18 3.70 1.99 А $ з / С4Аз $ (molar ratios) 0.76 3.66 2.14 0.38 Temperature 5 ^and C Rc (MPa) 3 hours 0.87 2.09 1.46 0.72 Rc (MPa) 7 days 33.90 28.66 35.58 31.57 Rc (MPa) 28 days 40.69 32.30 45.20 42.04 Temperature 35 ^U C Rc (MPa) 3 hours 8.41 5.42 7.19 11.06 Rc (MPa) 7 days 44.68 52.12 50.30 58.09 Rc (MPa) 28 days 55.84 50.58

The accelerator compositions used in compositions 1 (for comparison), 2, 3 and 11 (for comparison) (Table 4) have a constant content of micronized anhydrite (20%), but with different content of sulfo-aluminum clinker (from 25 up to 65%) and corresponding aluminum sulphate content (from 15 to 55%).

These 4 compositions show that at low temperature (5 ° C) the increase in the ratio of sulfo-aluminum clinker in the composition of the accelerator is unfavorable in terms of mechanical stability at 3 hours. Conversely, the mechanical resistance at 3 hours and at 5 ° C improves with increasing aluminum sulphate content in the accelerator composition.

Example 2: Different sources for granules and Portland cement

Table 5

Composition № 3 4 5 Cement I CEM I 52.5 N PM ES “HRC” (Gaurain) 280 260 Cement I CEM I 52.5 N PM ES “HRC” (St Vigor) 260 Wasselone type sand 698 Cormeilles type sand 698 698 Water / cement 0.45 0.45 0.45 Accelerator / cement ratio 0.16 0.16 0.16 Sulfo-aluminum clinker (%) 35 35 35 Aluminum sulfate (%) 45 45 45 Anhydrite (%) 20 20 20 CS / C4A3S (molar ratios) 3.70 3.70 3.70

А $ з / С4Аз $ (molar ratios) 2.14 2.14 2.14 Temperature 5 ^and C Re (MPa) 3 hours 1.46 1.79 2.35 Rc (MPa) 7 days 35.58 31.83 33.58 Rc (MPa) 28 days 45.20 Temperature 20 ^and C Rc (MPa) 3 hours 2.45 3.12 Rc (MPa) 7 days 34.19 34.48 Rc (MPa) 28 days Temperature 35 ^and C Rc (MPa) 3 hours 7.19 7.57 8.73 Rc (MPa) 7 days 50.30 47.88 35.76 Rc (MPa) 28 days 50.58

The accelerator used in formulations 3, 4 and 5 (Table 6) has a constant composition: it includes 35% sulfo-aluminum clinker, 45% aluminum sulfate and 20% micronized anhydrite (weight percent).

These compositions were tested to evaluate, on the one hand, the influence of the origin of the granules (compositions 3 and 4), and, on the other hand, the influence of the origin of the cement (compositions 4 and 5) on the mechanical properties. It can be seen that the influence of the accelerator used in the three compositions does not change with the change of the origin of the cement and the granules.

Example 3: Changes in the content of aluminum sulfate

Table 6

Composition № 7 10 Cement CEM 152.5 N PM ES “HRC” 260 Cement 152.5 N PM ES “HRC” (Gaurain) 260 Wasselone type sand 698 698 Water / cement 0.45 0l45 Accelerator / cement ratio 0.16 0.16 Sulfo-aluminum clinker (%) 55 35 Aluminum sulfate (%) 25 53 Anhydrite (%) 20 12 C $ / C4Az $ (molar ratios) 2.36 2.22 А $ з / С4Аз $ (molar ratios) 0.76 2.52

Temperature 5 ^and C Rc (MPa) 3 hours 0.49 2.00 Rc (MPa) 7 days 41.90 34.32 Rc (MPa) 28 days 46.21 35.82 Temperature 35 ° C Rc (MPa) 3 hours 2.74 8.19 Rc (MPa) 7 days 45.06 29.02 Rc (MPa) 28 days 52.15 33.80

Compositions 7 (for comparison) and 10 (Table 6) have a weight ratio of sulfoaluminum clinker to total, constant amount of sulfoaluminum clinker and anhydrite (0.73). Teddy two compositions differ in the content of aluminum sulfate in the composition of the accelerator.

It was found that increasing the amount of aluminum sulfate improves the mechanical resistance at 3 hours, but adversely affects the characteristics over longer periods of time (from 7 days to 28 days).

Example 4: Different ratios of sulfo-aluminum clinker / aluminum sulfate

Table 7

Composition № 8 10 Cement I CEM I 52.5 N PM ES “HRC” (Gaurain) 260 260 Wasselone type sand 698 698 Water / cement 0.45 0.45 Accelerator / cement ratio 0.16 0.16 Sulfo-aluminum clinker (%) 45 35 Aluminum sulfate (%) 38 53 Anhydrite (%) 17 12 CS / CiAjS (molar ratios) 2.45 2.22 А $ з / С4Аз $ (molar ratios) 1.40 2.52 Temperature 5 ° C Rc (MPa) 3 hours 0.75 2.00 Rc (MPa) 7 days 38.36 34.32 Rc (MPa) 28 days 38.12 35.82 Temperature 35 ^(, C

Rc (MPa) 3 hours 5.62 8.19 Rc (MPa) 7 days 41.21 29.02 Rc (MPa) 28 days 42.20 33.80

The compositions used for the accelerators № 8 (for comparison) and № 10 (Table 7) are at close ratios of C $ / C ₄ Az $ (about 2.3), but differ in terms of the ratios of A $ h / C ₄ Az $ which are very different.

It was found that at a very high ratio for A $ 3 / C ₄ I $ favors mechanical stability in the short term and adversely affects the mechanical resistance in the long run (especially in high temperature conditions). These observations correspond to the results obtained from the example !.

Example 5: Presence of superplasticizer (Melflux 2651 F)

Table 8

Composition № 12 13 14 Cement 152.5 N PM ES “HRC” 260 260 260 Cormeilles type sand 698 698 698 Water / cement 0.385 0.385 0.385 Accelerator / cement ratio 0.16 0.16 0.16 Sulfo-aluminum clinker (%) 55 25 35 Aluminum sulfate (%) 25 55 45 Anhydrite (%) 20 20 20 C $ / C ₄ I $ (molar ratios) 2.36 5.18 3.70 A $ h / C ₄ I $ (molar ratios) 0.76 3.66 2.14 Temperature 5 ^and C Rc (MPa) 3 hours 1.14 3.65 4.41 Rc (MPa) 7 days 69.8 33.66 42.07 Rc (MPa) 28 days 81.64 58.23 Temperature 20 ^and C Rc (MPa) 3 hours 7.73 6.11 9.2 Rc (MPa) 7 days 81.08 43.52 73.35 Rc (MPa) 28 days 82.38 86.92 Temperature 35 ° C Rc (MPa) 3 hours 18.89 8.19 10.92 Rc (MPa) 7 days 78.24 69.01 35.74 Rc (MPa) 28 days 85.3 36.02

From all compositions, "functional" samples (sample samples 4 x 4 x 16) were prepared, ie. those with shrinkage resistance above 0.4 MPa at 3 hours; and over 30 MPa at 28 days, at a treatment temperature of + 5 ° C to + 35 ° C.

Formulations 12 (for comparison), 13 and 14 (Table 8), respectively, have the same composition as that of compositions 1 (for comparison), 2 and 3 (Table 2), but with a larger amount of super-plasticizer - 0.9 wt. % in relation to cement.

It has been found that, in general, the presence of a super-plasticizer improves the mechanical properties of concretes, in particular those measured at 7 days and at 28 days.

Example 6: Shotcrete made in a gallery

Table 9

Composition № 17 18 Accelerator + super-plasticizer / cement ratio 0.165 0.165 Sulfo-aluminum clinker (%) 35 35 Aluminum sulfate (%) 45 45 Anhydrite (%) 20 20 Temperature 14 ° C Rc (MPa) 3 hours 7.3 13.4 Rc (MPa) 24 hours 39.6 22.3 Rc (MPa) 7 days 53.5 34.6 MS (MPa) 28 days 63.4 43.1

Table 9 shows the characteristics of the shotcrete concretes according to the present invention, which were obtained from the studies of 3 tons of concrete obtained with the granule type Cormeilles (composition 17) and type Wesselonne (composition 18). Gaurain type cement (CEM I 52.5 N PM ES 'HRC') was used in these two compositions. The tests were performed in a gallery at 14 ° C and at 95% relative humidity.

The super-plasticizer (MelfluxX 265IF) is in amounts of 0.5% relative to the cement (in weight ratios). The E / C ratio is 0.38. The total weight of the accelerator according to the present invention and the weight of the over-plasticizer constitute 4.3% by weight of the total weight of the concrete obtained (dry state).

The resistance measurement is performed on cubic test specimens (10 x 10 x 10 cm). The 24-hour measurement for composition 18 was the average of two results.

Example 7: (for comparison)

The compositions shown in Table 10 are the so-called "non-functional" compositions, i. they do not achieve the expected stability (resistance to shrinkage above 0.4 MPa, at 3 hours; and above 30 MPa, at 28 days, at operating temperatures from + 5 ° C to + 35 ° C), within the current invention.

Three formulations have been prepared to demonstrate that the presence of a sulphate source with a solubility of less than 4 g l ' ¹ and Portland cement is not sufficient to achieve acceleration of hardening and thickening (compositions without added anhydrites).

The latter composition 22 makes it possible to compare the accelerator according to the present invention with an accelerator according to the prior art (Sigunit 49 AF (SikA)).

Table 10

Composition № 18 20 21 22 Cement 152.5 N PM ES “HRC” (Beaucaire) 240 Cement 152.5 N PM ES “HRC” (Gaurain) 240 240 240 Wasselone type sand 722 726 722 726 Water / cement 0.45 0.45 0.45 0.45 Accelerator / cement ratio 0.16 0.14 0.16 0.14 Sulfo-aluminum clinker (%) 30 30 30 Aluminum sulfate (%) 70 70 70 Anhydrite (%) 0 0 0 C $ / СдАз $ (molar ratios) 0 0 0 - А $ з / СдАз $ (molar ratios) 3.88 3.88 3.88 - Temperature 5 ^and C Rc (MPa) 3 hours 0.60 1.81 - 1.02 Rc (MPa) 7 days 11.69 - - 15.01 Rc (MPa) 28 days 15.61 37.70 - 19.54 Temperature 20 ^and C Rc (MPa) 3 hours - - 4.11 - Rc (MPa) 7 days - - 12.45 -

Rc (MPa) 28 days - - 12.02 - Temperature 35 ° C Rc (MPa) 3 hours 1.72 3.49 - 3.18 Rc (MPa) 7 days 13.46 - - 4.02 Rc (MPa) 28 days 14.09 8.12 - 5.62

Composition 19 (for comparison)

The accelerator used in composition 19 contains 30% sulfo-aluminum clinker, 70% aluminum sulfate and does not contain micronized anhydrite (weight ratios).

Composition 19 is based on Portland cement type Beaucaire.

It was found that the values for stability at 28 days are half of those achieved. These compositions are considered "non-functional" because their mechanical resistance at + 5 ° C and at + 35 ° C is less than 30 MPa.

Composition 20 (for comparison)

The accelerator used in composition 20 contains 30% sulfo-aluminum clinker, 70% aluminum sulfate, and does not contain micronized anhydrite (in weight percent).

Gaurain Portland cement was used for composition 20 and the ratio between accelerator and Portland cement was 0.14.

It was found that the resistance at 28 days is acceptable at low temperatures, but is very unsatisfactory at a temperature of + 35 ° C. The resistance is below the required 30 MPa.

Composition 21 (for comparison)

The accelerator used in composition 21 contains 30% sulfo-aluminum clinker, 70% aluminum sulfate, and does not contain micronized anhydrite (in weight percent).

The composition 21 is comparable to the composition 19, except for the cement used, the nature of which may be different. Gaurain Portland cement is used in this composition 21.

It was found that the resistance at 28 days is very low at + 20 ° C and is below 30 MPa for shrinkage resistance at 28 days.

Composition 22 (for comparison)

The composition 22 contains a curing accelerator commercially available under the name Sigunit 49 AF from SIKA, instead of the accelerator according to the present invention.

For composition 22, an accelerator to Portland cement ratio of 0.14 is used.

Resistance at 28 days was found to be low at low temperatures. Resistance is very low, also at high temperatures at 28 days. At + 35 ° C the resistance stabilizes very quickly to low values: on the order of 5 MPa even for 7 days.

Claims (14)

CLAIMS \ J1. Accelerator for hardening and hardening of hydraulic solutions, containing the following weight ratios: - from 25 to 35% of at least one sulpho-aluminum clinker, - from 45 to 55% of at least one source of sulphates with a solubility above 4 g ^{-1 l} , in water, at 20 ° C, and - from 10 to 20% of at least one source of sulphates with a solubility below 4 g, in water, at + 20 ° C, the clinker containing mineralogical compounds of the calcium aluminate type. Compression and hardening accelerator according to claim 1, characterized in that the mineralogical compounds from the calcium aluminate tier contained in the clinker are optionally from Yeelmite (C4A3), Mayenite (C12A7), calcium mono-aluminate ( CA), tetra-calcium aluminoferrite (C4AF), tri-calcium aluminate (C3A) or a combination of several of these compounds; the combination of Yeelmite and one or more of the other calcium aluminate type mineralogical compounds is recommended. Compression and curing accelerator according to claims 1 and 2, characterized in that the at least one source of sulphates with a solubility below 4GP-L ' ¹ is optionally of gypsum (CaBO 4, H 2 O), anhydrite (CaSO4) or a mixture thereof. A thickening and curing accelerator according to any one of claims 1 to 3, characterized in that this at least one source of sulphates with a solubility of more than 4 g of ^{l -1} is optionally hydrated from dodeca to octadeca aluminum sulphate (A1r (8O4) 3-12 to 18 H2O), tetra to hepta hydrated ferrous sulphate (Fe (SO4) .4 to 7 H2O), gypsum (Ca3C3H3O) or a mixture thereof. A thickening and curing accelerator according to any one of claims 1 to 4, characterized in that the molar ratio between the source of sulphates with a solubility of more than 4 g. L ' ¹ and the mineralogical compounds of the type of calcium aluminates is in ranging from 0.3 to 55, preferably from 0.4 to 12. A thickening and hardening accelerator according to any one of claims 1 to 4, characterized in that the molar ratio between the source of sulphates with a solubility above 4 g. L ' ¹ and the mineralogical compounds of the type of calcium aluminates is in in the range from 0.15 to 27, preferably from 0.3 to 10. Compression and curing accelerator according to any one of claims 1 to 6, characterized in that - the clinker is a sulpho-aluminum clinker containing more than 30% by weight of Yeelmite (C4AZ $), preferably 50 to 70% by weight of Yeelmite, and - the source of sulphates with a solubility of more than 4 g '' is aluminum sulphate, and - the source of sulphates with solubility below 4GR.L ' ¹ is gypsum or anhydrite. y Cement compositions comprising a hydraulic mortar, a compaction and hardening accelerator according to any one of the preceding claims and optionally water. Cement composition according to claim 8, characterized in that the hydraulic solution is a Portland type binder, optionally of CEM I, III IV or V, preferably CEM I, and even more preferably CEM IPMES. Cement mortar according to claims 8 and 9, characterized in that the weight ratio between the compression and hardening accelerator and the hydraulic mortar is from 0.1 to 0.2; preferably from 0.14 to 0.18, more preferably from 0.15 to 0.17. Cement composition according to any one of claims 8 to 10, characterized in that the cement composition also comprises a thickening and hardening accelerator and a hydraulic solution, one or more auxiliaries, optionally a super-plasticizer, and / or compression retarders. j Use of a cementitious composition as defined in any one of claims 8 to 11, in admixture with fine granules, coarse granules with a maximum diameter of less than 12 mm, optionally very fine granules, water and possibly excipients, for the production of shotcrete. concrete. ~ xj Use of a cementitious composition as defined in any one of claims 8 to 11, in admixture with fine granules, water, and optionally very fine granules, and optionally excipients, for the preparation of a leveling and compaction mortar. . Use of a cementitious composition according to any one of claims 8 to 11, characterized in that the mixture is used in the temperature range from 5 ° C to 35 ° C, approx. Concrete or mortar containing a cementitious composition according to any one of the preceding claims 8 to 11, used in the temperature range from 5 ° C to 35 ° C, approximately characterized in that they have a mechanical resistance to shrinkage at 3 hours above 0.4 MPa, in particular above 1 MPa, preferably above 2 MPa, and mechanical resistance to shrinkage at 28 days above 30 MPa.