Hydraulic binder composition comprising blast furnace slag

Abstract

The present invention relates to a hydraulic binder composition comprising: - a hydraulic binder comprising at least one aluminosilicate compound, preferably blast furnace slag, and an alkaline or sulfate activator and a maximum of 10 wt.% of clinker, preferably between 0 and 10 wt.% of clinker; - nitric acid or one of its salts except zinc nitrate.

Description

[0001] Hydraulic binder composition of blast furnace slag

[0002] The present invention relates to a hydraulic binder composition comprising at least one alumino-siliceous compound and an alkaline or sulfate activator, and a reduced quantity of clinker and the maintenance of the workability of the hydraulic composition obtained, in particular by adding water to the hydraulic binder composition.

[0003] Common cement compositions include a variable, sometimes significant, proportion of clinker. For example, a cement composition according to the NF EN 197-1 standard of 2012 includes 5 to 95% by weight of clinker.

[0004] However, clinker production requires the use of powerful kilns, which generate significant amounts of carbon dioxide. Extraction of raw materials also produces carbon dioxide.

[0005] We are therefore seeking to lower the clinker content of cement compositions in order to reduce their carbon impact, while maintaining their mechanical and rheological properties.

[0006] For this purpose, new hydraulic binder compositions are being developed in which the amount of clinker is reduced.

[0007] Cementitious compositions in which the hydraulic binder is an alumino-siliceous compound, for example, blast furnace slag, have been described; these compositions are generally activated. However, the workability of these compositions drops very rapidly, meaning that they change from a fluid to almost solid state in less than 30 minutes. From a rheological point of view, threshold stresses of 1 to 10 Pa are typically observed five minutes after mixing, increasing to 50 to 100 Pa between 30 and 60 minutes after mixing.

[0008] There is therefore an interest in providing a solution making it possible to improve the fluidity of compositions comprising at least one alumino-siliceous compound, preferably blast furnace slag.

[0009] An objective of the present invention is to provide a hydraulic binder composition comprising at least one alumino-siliceous compound and an alkaline or sulfate activator making it possible to obtain a hydraulic composition having improved fluidity maintenance. Another objective of the present invention is to provide a hydraulic binder composition comprising at least one alumino-siliceous compound and an alkaline or sulfate activator having good thixotropic properties and a good compromise between thixotropic properties and mechanical strength, in particular at 28 days.

[0010] Another objective of the present invention is to provide such a composition allowing fluidity to be maintained for 1 hour or 1 hour 30 minutes.

[0011] Still other objectives will appear upon reading the description of the invention which follows.

[0012] All these objectives are fulfilled by the present application which relates to a hydraulic binder composition (HBC) comprising: a hydraulic binder comprising at least one alumino-siliceous compound and an alkaline or sulfate activator and a maximum of 10% by weight of clinker, preferably from 0 to 10% by weight of clinker; nitric acid or one of its salts, the nitric acid salt not being a zinc nitrate.

[0013] The inventors have advantageously shown that the addition of nitric acid or one of its salts, with the exception of zinc nitrate, according to the invention allows the improvement of the maintenance of fluidity (also called maintenance of workability) over time of a hydraulic composition prepared from the hydraulic binder composition (CLH), in particular by adding at least water, compared to a composition not comprising nitric acid or one of its salts according to the invention.

[0014] In the context of the present invention, the improvement in maintaining workability, measured for example by the change in the threshold stress of a hydraulic composition obtained from the CLH composition, in particular by adding water, over time, is preferably long term, namely over a period greater than or equal to 45 minutes, in particular greater than 60 minutes, or even greater than 90 minutes when the composition is used at 20°C. Threshold stresses of the order of 1 to 10 Pa are therefore desired during the same time intervals, i.e. over a period greater than or equal to 45 minutes, in particular greater than 60 minutes, or even greater than 90 minutes when the composition is used at 20°C.

[0015] The threshold stress can be measured using a rheometer by taking several measurements of the applied stress to obtain each corresponding strain rate value. The applied stress below which the strain rate becomes very low or zero can be considered the threshold stress.

[0016] Thus, the inventors have shown that the use of nitric acid or one of its salts, with the exception of zinc nitrate, makes it possible to provide thixotropic properties to the hydraulic composition advantageously without significantly modifying the mechanical resistances, in particular the mechanical resistances at 28 days.

[0017] The hydraulic binder composition (CLH) may be clinker-free.

[0018] In the context of the present invention, the clinker may be a Portland cement, sulfoaluminous or sulfobelitic cement clinker.

[0019] In the context of the present invention, the term alumino-siliceous compound means blast furnace slags of pozzolanic materials (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.3), fly ash (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.4), calcined schists (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.5), or silica fumes (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.7) or mixtures thereof. Other minerals, not currently recognized by the Cement standard NF EN 197-1 (2012), may also be used.These include metakaolins, such as type A metakaolins conforming to standard NF P 18-513 (August 2012) or calcined clays, siliceous additions, such as siliceous additions of Qz mineralogy conforming to standard NF P 18-509 (September 2012), alumino-silicates, particularly of the inorganic geopolymer type, alumino-silicates containing iron oxides such as bauxite residues, norites or aplites from excavations.

[0020] Preferably, the alumino-siliceous compound is chosen from blast furnace slags, pozzolanic materials (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.3), fly ash (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.4), calcined schists (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.5), metakaolins, such as type A metakaolins conforming to the standard NF P 18-513 (August 2012) or calcined clays, alumino-silicates, in particular of the inorganic geopolymer type, alumino-silicates containing iron oxides such as bauxite residues, norites or aplites originating from excavations. The composition of the invention may comprise a mixture of alumino-siliceous compounds.

[0021] Preferably, the hydraulic binder composition comprises from 75 to 99% by weight of alumino-siliceous compound, preferably from 80 to 95% by weight, for example from 80 to 90% by weight, relative to the total weight of hydraulic binder.

[0022] In one embodiment, the hydraulic binder consists of an alumino-silica compound and an alkaline or sulfate activator.

[0023] The hydraulic binder may also comprise mineral additions, preferably from 0 to 10% by weight relative to the weight of hydraulic binder.

[0024] The term "mineral additions" refers to pozzolanic materials (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.3), calcined schists (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.5), limestones (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.6) or silica fumes (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.7) or their mixtures. Other additions, not currently recognized by the Cement standard NF EN 197-1 (2012), may also be used. These include siliceous additions, such as siliceous additions of Qz mineralogy in accordance with standard NF P 18-509 (September 2012).The proportions of additions and their nature may also comply with standard prEN 197-5, which defines CEM ll / CM cements comprising between 50 and 64% clinker and 36 to 50% blast furnace slag and CEM VI cements comprising 35 to 49% clinker, 31 to 59% blast furnace slag and 6 to 20% mineral additions as defined above.

[0025] Preferably, the alumino-siliceous compound is a blast furnace slag and the hydraulic binder may also comprise mineral additions.

[0026] Blast furnace slag is defined in particular in parts 3.7 and 3.6 of the NF EN 15167-1 standard. Blast furnace slags are predominantly vitreous materials and are by-products of cast iron manufacturing. Blast furnace slags used in hydraulic binder compositions are finely ground, preferably to a maximum diameter of 100 to 150 μm, the diameter being measured by any method known to those skilled in the art, for example by laser granulometry. Blast furnace slags generally require calcium or sulfo-calcium activation or using a strong base. The term “mineral additions” means pozzolanic materials (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.3), fly ash (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.4), calcined schists (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.5), limestones (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.6) or silica fumes (as defined in the Cement standard NF EN 197-1 (2012) paragraph 5.2.7) or their mixtures. Other additions, not currently recognized by the Cement standard NF EN 197-1 (2012), can also be used. These include metakaolins, such as type A metakaolins conforming to the standard NF P 18-513 (August 2012) or calcined clays, siliceous additions, such as siliceous additions of Qz mineralogy conforming to the standard NF P 18-509 (September 2012), alumino-silicates, particularly of the inorganic geopolymer type.The proportions of additions and their nature may also comply with standard prEN 197-5, which defines CEM ll / CM cements comprising between 50 and 64% clinker and 36 to 50% blast furnace slag and CEM VI cements comprising 35 to 49% clinker, 31 to 59% blast furnace slag and 6 to 20% mineral additions as defined above.

[0027] The hydraulic binder composition (CLH) of the invention comprises at least one alkaline or sulfate activator of alumino-siliceous compounds, in particular blast furnace slags. These activators are known and in particular described in Alkaline activation of different aluminosilicates as an alternative to Portland cement: alkali activated cements or geopolymers. Revista Ingeniena de ConstrucciônRICVol 32 N e22017. Preferably the activator is a calcium or sulfate activator, preferably sulfo-calcium, or an alkali salt, preferably carbonate, hydroxide, silicate, sodium or potassium, or mixtures thereof or a calcium sulfate activator. This activator is preferably used in proportions of 0.1 to 20% by dry weight relative to the weight of hydraulic binder, preferably 1% to 20% by dry weight relative to the weight of hydraulic binder.

[0028] Thus, the hydraulic binder composition may also include calcium sulfate, in particular in a proportion of 5 to 20% by weight. Such hydraulic binder compositions are also called super-sulfated cement (CSS) and are in particular as defined in standard NF EN 15743+A1.

[0029] Preferably, the hydraulic binder comprises, preferably consists of a blast furnace slag, an activator and from 0 to 10% by weight of clinker. Preferably, the hydraulic binder consists of a blast furnace slag and an activator as described above.

[0030] Preferably, the nitric acid salts are alkali or alkaline earth metal salts. Preferably, the nitric acid salts are calcium or sodium salts, preferably calcium salts.

[0031] It is known to add calcium nitrate to Portland cement compositions to accelerate the setting of the hydraulic composition. The inventors surprisingly discovered that adding nitric acid or salts to systems based on blast furnace slag and low in clinker (in particular less than 10% by weight of clinker) made it possible to fluidize them.

[0032] The amount of nitric acid or one of its salts in the hydraulic binder composition (CLH) is between 0.1 and 5% by dry weight, preferably between 1.0 and 2.5% by dry weight, relative to the total weight of hydraulic binder.

[0033] Preferably, the amount of nitric acid or one of its salts in the hydraulic binder composition (CLH) is between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

[0034] The hydraulic binder composition may also comprise a polymer (P) comprising units of the following formulae (I) and (II): in which:

[0035] - R 1 and R 2 independently represent a hydrogen or a methyl,

[0036] - R 3 represents a hydrogen or a group of formula -COO(M)i / m

[0037] - R 4 represents a group of formula -(CH2) P -(OAIk)q-R5in which:

[0038] - p represents 1 or 2,

[0039] - q represents an integer from 3 to 300,

[0040] - the Alk of each OAlk unit of the group -(OAIk) q - independently represents a linear or branched alkylene comprising from 2 to 4 carbon atoms,

[0041] - R 5 represents -OH or a linear or branched alkoxyl comprising from 1 to 4 carbon atoms,

[0042] - R 11 and R 12 independently represent hydrogen or methyl, - R 13 represents a hydrogen or a group of formula -COO(M)i / m ,

[0043] - M represents H or a cation of valence m,

[0044] - when M represents H, m represents 1 and when M represents a cation, m is the valence of the cation M,

[0045] - a is a number from 0.05 to 0.25, such that (100 x a) represents the molar percentage of units of formula (I) within the polymer, and

[0046] - b is a number from 0.75 to 0.95, such that (100 x b) represents the molar percentage of units of formula (II) within the polymer.

[0047] Preferably, the CLH composition comprises from 0.1 to 3.0% by dry weight of polymer (P), preferably from 0.3 to 1.0% by dry weight of polymer (P), relative to the total weight of hydraulic binder.

[0048] In the context of the present invention, the term "total weight of hydraulic binder" means the weight of the alumino-siliceous compounds, the activator, the clinker if present, and the mineral additions if present.

[0049] The following embodiments for formulas (I) and (II) of the units of the polymer (P) can be considered independently or combined with each other:

[0050] - R 1 represents H,

[0051] - R 3 represents H,

[0052] - R 1 and R 3 represent H,

[0053] - R 2 represents a methyl,

[0054] - p represents 1,

[0055] - Alk represents -CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CHMe-, - CHMe-CH2-,

[0056] - at least 80% of the Alk of the group -(OAIk) q - represent -CH2-CH2-, or even all the Alk of the group -(OAIk) q - represent -CH2-CH2-,

[0057] - q represents an integer from 5 to 200, in particular from 10 to 100, preferably from 25 to 75,

[0058] - R 5 represents -OH or -OMe, preferably R 5 represents -OH,

[0059] - the sum of a and b is 1,

[0060] - R 11 represents H,

[0061] - R 13 represents H,

[0062] - R 11 and R 13 represent H,

[0063] - R 12represents H, and / or - M represents H or a monovalent or bivalent cation, m then representing 1 or 2, the monovalent cation preferably being chosen from an ammonium salt NH4 + , a primary, secondary, tertiary or quaternary ammonium cation and a cation of an alkali metal, such as a sodium, lithium or potassium ion, and the bivalent cation preferably being a cation of an alkaline earth metal, such as a magnesium or calcium ion,

[0064] - a is a number from 0.05 to 0.20, preferably a represents a number between 0.10 and 0.20,

[0065] - b is a number from 0.80 to 0.95, preferably b represents a number between 0.80 and 0.90.

[0066] Preferably, the units of formula (I) of the polymer (P) have the following formula (I'): in which:

[0067] - R 2 independently represents hydrogen or methyl, preferably methyl,

[0068] - R' 4represents a group of formula -CH2-(O-CH2-CH2)q-R5 in which:

[0069] - q represents an integer from 3 to 500,

[0070] - R 5 represents -OH or -OMe, preferably -OH,

[0071] - a is a number from 0.05 to 0.25, such that (100 x a) represents the molar percentage of units of formula (I') within the polymer (P).

[0072] Preferably, the units of formula (II) of the polymer (P) have the following formula (II'): in which:

[0073] - R 12 represents hydrogen or methyl, preferably hydrogen,

[0074] - M represents H or a cation of valence m,

[0075] - when M represents H, m represents 1 and when M represents a cation, m is the valence of the cation M, - b is a number from 0.75 to 0.95, such that (100 x b) represents the molar percentage of units of formula (II') within the polymer.

[0076] Preferably, the polymer (P) comprises units of formulas (I') and (II').

[0077] The following embodiments for formulas (I') and (II') of the polymer (P) can be considered independently or combined with each other:

[0078] - q represents an integer from 5 to 200, in particular from 10 to 100, preferably from 25 to 75,

[0079] - R 5 represents -OH or -OMe, preferably R 5 represents -OH,

[0080] - a is a number from 0.05 to 0.20, preferably a represents a number between 0.10 and 0.20,

[0081] - b is a number from 0.80 to 0.95, preferably b represents a number between 0.80 and 0.90,

[0082] - the sum of a and b is 1 (which implies that the polymer is made up of units of formulas (I) and (II)), and / or

[0083] - M represents H or a monovalent or bivalent cation, m then representing 1 or 2, the monovalent cation preferably being chosen from an ammonium salt NH4 + , a primary, secondary, tertiary or quaternary ammonium cation and a cation of an alkali metal, such as a sodium, lithium or potassium ion, and the divalent cation preferably being a cation of an alkaline earth metal, such as a magnesium or calcium ion.

[0084] The polymer (P) may comprise one or more additional units in addition to those of formula (I) and (II). Preferably, the polymer (P) is free of the following unit of formula (III): in which M represents H or a cation, such as sodium. Particularly preferably, the polymer (P) is free of sulfonic acid and sulfonate groups.

[0085] Preferably, the polymer (P) consists of the units of formulae (I) and (II). It does not comprise any additional units in addition to those of formulae (I) and (II). The sum of a and b is then 1.

[0086] The weight average molar mass of the polymer is generally 10,000 to 200,000 g / mol, especially 10,000 to 100,000 g / mol.

[0087] Generally, the polymer (P) is obtained by free radical polymerization. The polymer (P) is therefore a comb polymer whose pendant groups are linked to the main carbon chain by ether groups.

[0088] The hydraulic binder composition (CLH) may also comprise polyalkoxylated polyphosphonate-based polymers, preferably in a proportion of between 0.1 and 3.0% by dry weight relative to the total weight of hydraulic binder optionally comprising mineral additions, preferably from 0.3 to 1.0% by dry weight, in particular described in patent EP0663892 (for example CHRYSOOFluid Optima 100).

[0089] In the context of the present invention, the polyalkoxylated phosphonate is preferably a polyalkoxylated phosphonate polymer of formula (V) or one of its salts, alone or as a mixture: in which:

[0090] R5 is a hydrogen atom or a monovalent hydrocarbon group comprising from 1 to 18 carbon atoms and optionally one or more heteroatoms; the Ri are similar or different from each other and represent an alkylene such as ethylene, propylene, butylene, amylene, octylene or cyclohexene, or an arylene such as styrene or methylstyrene, the Ri optionally contain one or more heteroatoms;

[0091] Q is a hydrocarbon group containing from 2 to 18 carbon atoms and optionally one or more heteroatoms;

[0092] A is an alkylidene group containing from 1 to 5 carbon atoms; the Rj are similar or different from each other and can be chosen from:

[0093] - the group A-PO3H2, A having the aforementioned meaning,

[0094] - the alkyl group containing from 1 to 18 carbon atoms and which can carry [R5-O(Ri-O)] groups m], R5 and Ri having the aforementioned meanings,

[0095] "m" is a number greater than or equal to 0,

[0096] "r" is the number of groups [R 5 -O(Ri-O) m ] carried by the set of Rj, "q" is the number of groups [R 5 -O(RiO) m ] carried by Q, the sum "r+q" is between 1 and 10,

[0097] "y" is an integer between 1 and 3, Q, N and Rj can together form one or more rings, this or these rings can also contain one or more other heteroatoms.

[0098] Particularly preferably, the polyalkoxylated phosphonate consists of a water-soluble or water-dispersible organic compound comprising at least one amino-di-(alkylene-phosphonic) group and at least one polyoxyalkylated chain or at least one of its salts.

[0099] Preferably, the polyalkoxylated phosphonate is a compound of formula (V) in which:

[0100] R 5 is a hydrogen atom or a monovalent hydrocarbon group, saturated or unsaturated, comprising from 1 to 8 carbon atoms and optionally one or more heteroatoms; the Ri represent ethylene or propylene or a mixture of ethylene or propylene, preferably 60 to 100% of the Ri are ethylene groups;

[0101] Q is a hydrocarbon group having from 2 to 8 carbon atoms and, optionally, one or more heteroatoms;

[0102] A is the methylene group; each of the Rj represents the CH2-PO3H2 group; m is an integer between 10 and 250; q is an integer equal to 1 or 2; y is an integer equal to 1 or 2.

[0103] In particular, the polyalkoxylated phosphonate may be a polyalkoxylated phosphonate of formula (V) in which R5 is a methyl group, Ri are ethylene and propylene groups, m being between 30 and 50, r+q is 1, Q is an ethylene group, A is a methylene group, y is 1 and Rj corresponds to the CH2-PO3H2 group.

[0104] Preferably, the hydraulic binder composition (CLH) according to the invention comprises from 0 to 3.0% by dry weight of polymer (P), preferably from 0 to 1% by dry weight of polymer (P), relative to the total weight of hydraulic binder.

[0105] The present application also relates to the use of nitric acid or one of its salts, with the exception of zinc nitrate, as defined above, for the preparation of a hydraulic binder composition as defined above or for the preparation of a hydraulic composition as defined above by adding nitric acid or one of its salts to a hydraulic binder composition comprising a hydraulic binder as defined above or to a composition comprising a hydraulic binder as defined above, water and optionally at least one granulate. The use according to the invention makes it possible to improve the fluidity maintenance of the hydraulic compositions compared to the same hydraulic composition not comprising nitric acid or one of its salts.

[0106] The present invention also relates to the use of the hydraulic binder composition (CLH) defined above for the preparation of a hydraulic composition (CH).

[0107] The invention also relates to a hydraulic composition (CH) comprising (or even consisting of) the hydraulic binder composition (CLH) defined above, water, and optionally at least one aggregate.

[0108] The present invention relates to a hydraulic composition (CH) comprising:

[0109] - a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkaline or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10% by weight of clinker, and optionally mineral additions as described above; water;

[0110] - possibly at least one granulate; nitric acid or one of its salts with the exception of zinc nitrate.

[0111] The alumino-siliceous compound, the activator and the mineral additions being as defined above.

[0112] The hydraulic composition may further comprise a polymer (P) as defined above.

[0113] The hydraulic binder, nitric acid and its salts, the activator, the mineral additions, as well as the polymer (P) are as defined above.

[0114] The hydraulic composition may further comprise a polymer based on polyalkoxylated polyphosphonates, preferably in a proportion of between 0.1 and 3.0% by dry weight relative to the weight of hydraulic binder, preferably from 0.3 to 1.0% by dry weight. This polymer is as described above.

[0115] The amount of nitric acid or one of its salts in the hydraulic composition is between 0.1 and 5% by dry weight, preferably between 1.0 and 2.5% by dry weight, relative to the total weight of hydraulic binder. Preferably, the amount of nitric acid or one of its salts in the hydraulic composition is between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

[0116] Preferably, the hydraulic composition comprises from 0 to 3.0% by dry weight of polymer (P), preferably from 0 to 1.0% by dry weight of polymer (P), relative to the total weight of hydraulic binder.

[0117] The hydraulic composition is preferably a composition of concrete, mortar or screed.

[0118] Aggregates are defined as a set of mineral grains with an average diameter of between 0 and 125 mm. Depending on their diameter, aggregates are classified into one of the following six families: fillers, sand, gravel, gravel and ballast (standard XP P 18-545). The most commonly used aggregates are:

[0119] - fillers, which have a diameter less than 2 mm and for which at least 85% of the aggregates have a diameter less than 1.25 mm and at least 70% of the aggregates have a diameter less than 0.063 mm, sands with a diameter between 0 and 4 mm (in standard 13-242, the diameter can go up to 6 mm),

[0120] - gravel with a diameter greater than 6.3 mm, gravel with a diameter between 2 mm and 63 mm.

[0121] Sands are therefore included in the definition of aggregate according to the invention.

[0122] Fillers can be of limestone or dolomitic origin.

[0123] Still other additives may be added to the hydraulic composition (CH) according to the invention, such as anti-air entrainment additives, antifoaming agents, a setting accelerator or retarder, a rheology modifying agent, another fluidizer (plasticizer or superplasticizer).

[0124] The present application also relates to a process for preparing a hydraulic composition according to the invention in which nitric acid or one of its salts, with the exception of zinc nitrate, the optional polymer (P) and the optional polymer based on polyalkoxylated polyphosphonate, are added to the hydraulic binder.

[0125] The present application also relates to a process for preparing a hydraulic composition according to the invention in which nitric acid or one of its salts, with the exception of zinc nitrate, the optional polymer (P) and the optional polymer based on polyalkoxylated polyphosphonate, is added with water, for example to the mixing water.

[0126] The hydraulic compositions are prepared in a conventional manner by mixing the aforementioned constituents. The polymer (P) according to the invention, and where appropriate the polymer based on polyalkoxylated polyphosphonate, can be added to the components of the hydraulic composition dry (generally in powder form) or in solution, preferably in aqueous solution. The water in said aqueous solution can be the mixing water or the pre-wetting water (part of the total water which is used to moisten the aggregates before mixing, making it possible to simulate the hygrometric state of the aggregates, which are often wet, in a concrete plant or on the construction site.

[0127] The present invention also relates to the use of nitric acid or one of its salts, with the exception of zinc nitrate, for the preparation of a hydraulic composition comprising a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkaline or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10.0% by weight of clinker, and optionally mineral additions as described above, water, optionally at least one aggregate.

[0128] The hydraulic binder, nitric acid and its salts, the activator, the mineral additions, are as defined above.

[0129] The present invention also relates to the use of nitric acid or one of its salts, with the exception of zinc nitrate, for improving the fluidity, in particular maintaining workability, of a hydraulic composition comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkaline or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10.0% by weight of clinker, and optionally mineral additions as described above, water, optionally at least one aggregate.

[0130] The hydraulic binder, nitric acid and its salts, the activator, the mineral additions, are as defined above.

[0131] The amount of nitric acid or its salts added to the hydraulic composition is between 0.1 and 5% by dry weight, preferably between 0.5 and 1.5% by dry weight, relative to the total weight of hydraulic binder. Preferably, the amount of polymer (P) added where appropriate to the hydraulic composition is between 0.1 and 3.0% by dry weight of polymer (P), preferably from 0.3 to 1.0% by dry weight of polymer (P), relative to the total weight of hydraulic binder.

[0132] Advantageously, the use according to the invention allows the improvement of the maintenance of fluidity (also called maintenance of workability) over time of the hydraulic composition compared to the same hydraulic composition not comprising nitric acid or its salts. This improvement in the maintenance of fluidity is as described above and makes it possible to obtain mechanical strengths at 24 hours of the same order of magnitude as a control not using the solution.

[0133] Advantageously, a polymer based on polyalkoxylated polyphosphonate as described above may also be added in particular in the proportions mentioned above.

[0134] The present invention also relates to a method for improving the maintenance of fluidity (also called maintenance of workability) over time of a hydraulic composition comprising a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkaline or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10% by weight of clinker, and optionally mineral additions as described above, water, optionally at least one aggregate, comprising the addition of nitric acid or one of its salts, with the exception of zinc nitrate as defined above.

[0135] This improvement in maintaining fluidity is as described above.

[0136] The hydraulic binder is as defined above.

[0137] Preferably, the method according to the invention comprises the addition of 0.1 to 5% by dry weight, preferably 1.0% to 2.5% by dry weight, relative to the total weight of hydraulic binder, of nitric acid or one of its salts. Preferably, the method according to the invention comprises the addition of 0.1 to 1.5% by dry weight, relative to the total weight of hydraulic binder, of nitric acid or one of its salts. The method of the invention may also comprise the addition of a polymer (P) as defined above.

[0138] Preferably, the method according to the invention, where appropriate, comprises the addition of 0.1% to 3.0% by dry weight of polymer (P), preferably 0.3 to 1.0% by dry weight of polymer (P), relative to the weight of hydraulic binder.

[0139] Nitric acid and its salts, and polymer (P) are as described above. The activator and mineral additions are as described above.

[0140] The method of the invention may further comprise the addition of polyalkoxylated polyphosphonate-based polymers, preferably in a proportion of between 0.1 and 3.0% by weight relative to the weight of hydraulic binder, preferably from 0.3 to 1.0% by weight. These polymers are as described above.

[0141] Nitric acid or its salts may be added to the hydraulic binder, and optionally the polymer (P) and the optional polyalkoxylated polyphosphonate-based polymer is added to the water, called mixing water. The polymer (P) according to the invention, and where appropriate the polyalkoxylated polyphosphonate-based polymer, may be added to the components of the hydraulic composition dry (generally in powder form) or in solution, preferably in aqueous solution. The water in said aqueous solution may be the mixing water or the pre-wetting water (part of the total water which is used to moisten the aggregates before mixing, making it possible to simulate the hygrometric state of the aggregates, often wet, in a concrete plant or on the construction site.

[0142] Nitric acid or its salts and, where appropriate, the polymer (P) and the possible polyalkoxylated polyphosphonate-based polymer may be added to the hydraulic binder.

[0143] The present invention will now be described with the aid of the examples below.

[0144] Thixotropy and fluidity monitoring tests on mortar

[0145] The composition of all mortars is as follows, only the composition of the binder changes depending on the case: [Table 1]

[0146] The mortar is stored in a Perrier-type mixer rotating continuously at 43 rpm. The slump measurements at the 700 cm cone 3 are carried out 5 min and 25 min after the start of mixing: to do this, the mixer is stopped for the time to fill the cone, then it is restarted.

[0147] After 25 minutes of mixing and the slump measurement, a quantity of mortar is placed in several sections of PVC pipe with a diameter of 44 mm and a height of 99 mm. The mortar is leveled and then a cover topped with a weight is added to prevent any evaporation and leakage of mortar from the bottom of the pipe.

[0148] At specific time intervals after placement, a pipe is lifted and the resulting mortar spread is measured. There comes a point where the mortar no longer flows and a cylinder is obtained reproducing the shape of the pipe. This point is noted and the results are then expressed as the time taken to reach this state.

[0149] Example 1 - Activated blast furnace slag mortars

[0150] The composition of the binder is given in the following table:

[0151] [Table 2]

[0152] The results obtained are as follows:

[0153] [Table 3]

[0154] It is clear that the adjuvanted version presents spreads greater than 5 and 25 min, a fluidity time before thixotropic consolidation longer than 15 min, while preserving the essential mechanical resistances, which decrease by 2 to 4 MPa depending on the temperature.

[0155] Example 2 - over-sulfated cement mortars The composition of the binder here is as follows:

[0156] [Table 4]

[0157] The results obtained are as follows:

[0158] [Table 5] the invention. The time before thixotropic stiffening is also significantly increased from 35 to 65 min. All this is achieved with a very small effect on the mechanical strengths at both temperatures. Example 3 - CEM lll / C type cement mortars activated by an alkaline compound

[0159] The binder is composed as follows:

[0160] [Table 6]

[0161] The performances obtained are as follows: [Table 7]

[0162]

[0163] The fluidity is slightly improved by the invention with spreads slightly higher than the control and a time before thixotropic stiffening a little longer of 15 min. The resistances are reduced by 5 to 7 MPa, but remain within an acceptable range.

Claims

DEMANDS 1. Composition of hydraulic binder comprising: - a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkali or sulfate activator and a maximum of 10% by weight of clinker, preferably from 0 to 10% by weight of clinker; - nitric acid or one of its salts, the salt of nitric acid not being a zinc nitrate, the quantity of nitric acid or one of its salts being between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

2. Hydraulic composition (CH) comprising: - a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkali or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10% by weight of clinker, and possibly mineral additions; - water; - possibly at least one aggregate; - nitric acid or one of its salts, the salt of nitric acid not being a zinc nitrate, the quantity of nitric acid or one of its salts being between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

3. Use of nitric acid or one of its salts, with the exception of zinc nitrate, to improve the fluidity, in particular the maintenance of workability, of a hydraulic composition comprising a hydraulic binder comprising at least one alumino-siliceous compound, preferably blast furnace slag, and an alkali or sulfate activator and a maximum of 10% by weight of clinker, preferably between 0 and 10.0% by weight of clinker, and possibly mineral additions, water, possibly at least one aggregate, the quantity of nitric acid or one of its salts being between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

4. A method for improving the long-term fluidity of a hydraulic composition comprising a hydraulic binder including at least one alumino-silica compound, preferably blast furnace slag, and an alkali or sulfate activator, and a maximum of 10% by weight of clinker, preferably between 0 and 10% by weight of clinker, water, and optionally at least one aggregate, comprising the addition to said hydraulic composition of nitric acid or one of its salts, with the exception of zinc nitrate, the quantity of nitric acid or one of its salts being between 0.1 and 1.5% by dry weight, relative to the total weight of hydraulic binder.

5. Hydraulic binder composition according to claim 1, hydraulic composition according to claim 2, use according to claim 3 or process according to claim 4, wherein the nitric acid salt is selected from alkali or alkaline earth metal salts, preferably the nitric acid salts are calcium or sodium salts, preferably calcium salts.

6. Hydraulic binder composition according to claim 1 and 5, hydraulic composition according to claim 2 and 5, use according to claim 3 and 5, or process according to claim 4 and 5, wherein the activator is selected from a calcium or calcium sulfo-activator or an alkali salt, preferably carbonate, hydroxide, sodium or potassium silicate, calcium sulfate.

7. Hydraulic binder composition according to claim 1, 5 and 6, hydraulic composition according to claim 2, 5 and 6, use according to claim 3, 5 and 6, or process according to claim 4, 5 and 6, wherein the alumino-siliceous compound is selected from blast furnace slags, pozzolanic materials (as defined in Cement standard NF EN 197-1 (2012) paragraph 5.2.3), fly ash (as defined in Cement standard NF EN 197-1 (2012) paragraph 5.2.4), calcined shale (as defined in Cement standard NF EN 197-1 (2012) paragraph 5.2.5), metakaolins, such as type A metakaolins conforming to standard NF P 18-513 (August 2012) or clays calcined, aluminosilicates in particular of the inorganic geopolymer type, alumino-silicates containing iron oxides such as bauxite residues, norites or aplites from excavations.

8. Hydraulic binder composition according to claim 1, 5, 6 and 7, hydraulic composition according to claim 2, 5, 6 and 7, use according to claim 3, 5, 6 and 7, or process according to claim 4, 5, 6 and 7, wherein the alumino-silica compound is blast furnace slag.

9. Hydraulic binder composition according to claim 1, 5, 6 to 8, hydraulic composition according to claim 2, 5, 6 to 8, or process according to the claims 4, 5, 6 to 8, wherein the hydraulic binder composition or the hydraulic composition further comprises: - a polymer (P) comprising units of the following formulas (I) and (II): in which: R 1 and R 2 independently represent a hydrogen or a methyl group, R 3 represents a hydrogen or a group with the formula -COO(M)i / m R 4 represents a group with the formula -(CH2)P -(OAIk)q-R5 in which: p represents 1 or 2, q represents an integer from 3 to 300, the Alk of each unit OAlk of the group -(OAIk) q - independently represents a linear or branched alkylene comprising 2 to 4 carbon atoms, R 5 represents -OH or a linear or branched alkoxyl comprising 1 to 4 carbon atoms, R 11 and R 12 independently represent a hydrogen or a methyl group, R 13 represents a hydrogen or a group with the formula -COO(M)i / m , M represents H or a cation of valence m; when M represents H, m represents 1, and when M represents a cation, m is the valence of the cation M; a is a number from 0.05 to 0.25, such that (100 x a) represents the mole percentage of formula (I) units within the polymer; and b is a number from 0.75 to 0.95, such that (100 x b) represents the mole percentage of formula (II) units within the polymer; and / or - polyalkoxylated polyphosphonate-based polymers; and / or - anti-air entrainment additives, anti-foaming agents, a setting accelerator or retarder, a rheology modifying agent, a fluidifier.

10. A method for preparing a hydraulic composition according to any one of claims 4 to 9, wherein nitric acid or one of its salts, with the exception of zinc nitrate, is added to the hydraulic binder.

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