FR3024727B1 - IMPROVING THE RHEOLOGY OF A HYDRAULIC COMPOSITION - Google Patents

Abstract

The present invention relates to a method for treating a pozzolanic material comprising a step of contacting the pozzolanic material with a mineral compound that can release a cation in solution, the mixture of the pozzolanic material and the inorganic compound comprising from 1 to 15% by weight of water, and the contacting between the pozzolanic material and the inorganic compound being carried out for at least 1 hour before the use of the pozzolanic material treated.

Description

IMPROVING THE RHEOLOGY OF A HYDRAULIC COMPOSITION

The present invention relates to the use of a mineral compound that can release a cation in solution for the treatment of a pozzolanic material.

One of the problems of hydraulic compositions comprising a pozzolanic material in partial replacement of the clinker is the reduction of spreading, especially 5 minutes after mixing. This decrease is due in particular to the demand for water and / or water-reducing agent of pozzolanic materials, which is higher than that of clinker.

There are several solutions for reducing the demand for water and / or water-reducing agent for pozzolanic materials and thus improving the rheology, in particular the spreading 5 minutes after mixing, of a hydraulic composition comprising a clinker and a material pozzolanic, but none of these solutions include a mineral compound that can release a cation in solution. Known solutions are generally chemical compounds, in particular polymers.

In order to meet the requirements of users, it has become necessary to find a means for improving the rheology of hydraulic compositions comprising a clinker and a pozzolanic material.

Also the problem to be solved by the invention is to provide a means for improving the spreading, particularly 5 minutes after mixing, a hydraulic composition comprising a clinker and a pozzolanic material.

Unexpectedly, the inventors have demonstrated that it is possible to use a mineral compound that can release a cation in solution in a particular process to improve the spreading, in particular 5 minutes after mixing, of a hydraulic composition. comprising a clinker and a pozzolanic material

The present invention relates to a method for treating a pozzolanic material comprising a step of contacting the pozzolanic material with a mineral compound that can release a cation in solution, the mixture of pozzolanic material and the inorganic compound comprising from 1 to 15% by weight of water, and the contacting between the pozzolanic material and the mineral compound being carried out for at least 1 hour, preferably for at least 1 day, before the use of the pozzolanic material treated.

Preferably, the inorganic compound can release a cation in aqueous solution.

Preferably, the mineral compound that can release a cation in solution is chosen from lime, potash, soda, cement kiln dusts, clinkers, cements and mixtures thereof. Preferably, the mineral compound that can release a cation in solution is chosen from lime, cements, clinkers and mixtures thereof. PA14011 EN

Preferably, the cation released in solution is selected from calcium, sodium, potassium and mixtures thereof.

Preferably, the amount of inorganic compound that can release a cation in solution is 0.5 to 15%, more preferably 1 to 10% expressed by weight relative to the weight of pozzolanic material.

The pozzolanic materials used according to the present invention may be chosen from natural or artificial pozzolans, for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.3 or in standard ASTM 595 chapter 8; fumed silica (for example as defined in standard NF EN 197-1 of February 2001 paragraph 5.2.7 or in standard ASTM 595 chapter 8); metakaolins (for example as defined in standard NF EN 197-1 of February 2001 section 5.2.3 or in standard ASTM 595 chapter 8) and biomass ash (for example as defined in standard ASTM 595 chapter 8). ).

Preferably, the pozzolanic material is chosen from natural or artificial pozzolans as described in standard NF EN 197-1 of February 2001 or in standard ASTM 595 chapter 8.

Preferably, the pozzolanic material is a metakaolin.

Preferably, the contacting between the pozzolanic material and the mineral compound that can release a cation in solution is a mixture or co-grinding.

If the contact between the pozzolanic material and the inorganic compound is a mixture, then the pozzolanic material preferably has a Dv90 less than or equal to 100 pm. If the contact between the pozzolanic material and the mineral compound is a co-grinding, then the size of the pozzolanic material does not matter.

If the pozzolanic material is not moist enough, that is to say if the pozzolanic material provides less than 10%, preferably less than 7% of water by weight relative to the mass of the mixture of pozzolanic material and of the mineral compound, water may be added when the pozzolanic material is brought into contact with the mineral compound that can release a cation in solution.

Preferably, the amount of water included in the mixture of the pozzolanic material and the mineral compound corresponds to the total water, that is to say the water initially and naturally present in the pozzolanic material and the water added to the pozzolanic material. mixed.

Preferably, the amount of water included in the mixture of pozzolanic material and the mineral compound that can release a cation in solution is from 1 to 10%, more preferably from 1 to 7% by weight relative to the mixture.

The present invention also relates to a treated pozzolanic material obtained by the process as described above.

PA14011 EN

The present invention also relates to a method for manufacturing a hydraulic binder comprising the following steps: a) treating a pozzolanic material according to the treatment method as described above, to obtain a pozzolanic material treated; b) at least 1 hour, preferably at least 1 day after step a), placed in contact between a clinker and a treated pozzolanic material as obtained according to step a).

Preferably, the amount of pozzolanic material treated according to the method described above is 5 to 75% by weight relative to the mass of binder, knowing that the binder comprises clinker, the possible calcium sulphate, the pozzolanic material treated according to the present invention and the possible further mineral addition.

Preferably, the amount of clinker is 20 to 95% by weight relative to the mass of binder, knowing that the binder comprises the clinker, the possible calcium sulphate, the pozzolanic material, the possible other mineral addition and the mineral compound capable of releasing a cation in solution.

The clinker may be selected from a Portland clinker, a sulfo-aluminous clinker, a belitic clinker, a sulfo-belitic clinker and mixtures thereof.

A clinker is obtained by high-temperature clinkerization of a mixture comprising limestone and, for example, clay. For example, a Portland clinker is a clinker as defined in standard NF EN 197-1 of February 2001.

A clinker is usually co-milled with calcium sulphate to give a cement. The calcium sulphate used includes gypsum (calcium sulfate dihydrate, CaSO4.2H2O), hemihydrate (CaSO4.1 / 2H2O), anhydrite (anhydrous calcium sulphate, CaSO4) or a mixture thereof. Gypsum and anhydrite exist in their natural state. It is also possible to use a calcium sulphate which is a by-product of certain industrial processes.

Preferably, the hydraulic binder comprises another mineral addition. The other mineral addition may, for example, be chosen from slags (for example as defined in standard NF EN 197-1 of February 2001, section 5.2.2), fly ash (for example as defined in standard NF EN 197-1 of February 2001, paragraph 5.2.4), calcined schists (for example as defined in the standard NF EN 197-1 of February 2001, paragraph 5.2.5), mineral additions based on carbonate calcium, for example limestone (for example as defined in standard NF EN 197-1 of February 2001, section 5.2.6) and their mixtures.

According to a variant of the process according to the present invention, the mineral compound can be brought into contact with a mixture of a pozzolanic material and another mineral addition.

PA14011 EN

Preferably, the amount of the other mineral addition is at most 70% by weight relative to the mass of binder, knowing that the binder comprises the clinker, the possible calcium sulphate, the pozzolanic material treated and the possible other mineral addition.

It is understood that replacing a portion of the clinker with a mineral addition reduces the carbon dioxide emissions (produced during the manufacture of the clinker) by decreasing the amount of clinker.

A hydraulic binder is a material that takes and hardens by hydration, for example a cement. A cement typically includes a clinker and calcium sulphate. The clinker may in particular be a Portland clinker.

For example, the cement may be: a Portland cement, which is generally a cement of the CEM I type according to standard NF EN 197-1 of February 2001 (see in particular Table 1 page 12); a pozzolanic cement, which is generally a cement of CEM IV type according to standard NF EN 197-1 of February 2001 (see in particular Table 1 page 12); or a compound cement, which is generally a CEM II, CEM III or CEM V type cement according to standard NF EN 197-1 of February 2001 (see in particular Table 1 page 12); an aluminous cement; a sulfoaluminous cement; a sulfo-belitic cement; or - a belitic cement.

The present invention also relates to a method of manufacturing a hydraulic composition, comprising a step of contacting water with a hydraulic binder as obtained according to the manufacturing method described above.

A hydraulic composition generally comprises a hydraulic binder and water, optionally aggregates and optionally adjuvants. Hydraulic compositions include both fresh and hardened compositions, such as cement grout, mortar or concrete. The hydraulic composition can be used directly on site in the fresh state and poured into a formwork adapted to the intended application, used in prefabrication plant or used as a coating on a solid support.

The amount of water is preferably such that the water / binder ratio is 0.2 to 1.0. The binder comprises clinker, any calcium sulphate, pozzolanic material treated and any other mineral addition.

The aggregates used include sand (whose particles generally have a maximum size (Dmax) less than or equal to 4 mm), and chippings (of which PA14011 FR particles generally have a minimum size (Dmin) greater than 4 mm and preferably a Dmax less than or equal to 20 mm).

Aggregates include calcareous, siliceous and silico-calcareous materials. They include natural, artificial materials, waste and recycled materials. Aggregates may also include, for example, wood.

The hydraulic composition can also comprise an adjuvant, for example one of those described in the standards EN 934-2 of September 2002, EN 934-3 of November 2009 or EN 934-4 of August 2009. Preferably, the hydraulic composition comprises also an adjuvant for hydraulic composition, for example an accelerator, an air entraining agent, a viscosity agent, a retarder, an inerting clays, a plasticizer and / or a superplasticizer. In particular, it is useful to include a superplasticizer, for example a polycarboxylate, in particular from 0.05 to 1.5%, preferably from 0.1 to 0.8% by weight.

Inerting clays are compounds that reduce or prevent the harmful effects of clays on the properties of hydraulic binders. Inerting clays include those described in WO 2006/032785 and WO 2006/032786.

The term "superplasticizer" as used in the present specification and accompanying claims is to be understood to include both water reducers and superplasticizers as described in the book entitled "Concrete Admixtures Handbook, Properties Science". and Technology, "VS Ramachandran, Noyes Publications, 1984.

A water reducer is defined as an adjuvant which typically reduces the amount of mixing water of a concrete by 10 to 15% for a given workability. Water reducers include, for example, lignosulfonates, hydroxycarboxylic acids, carbohydrates and other specialized organic compounds, for example glycerol, polyvinyl alcohol, sodium alumino-methyl-siliconate, sulfanilic acid and casein.

Superplasticizers belong to a new class of water reducers, chemically different from normal water reducers and able to reduce water amounts by about 30%. Superplasticizers were broadly classified into four groups: sulfonated condensates of naphthalene formaldehyde (SNF) (usually a sodium salt); sulphonated condensates of melamine formaldehyde (SMF); modified lignosulfonates (MLS); And the others. More recent superplasticizers include polycarboxylic compounds such as polycarboxylates, for example polyacrylates. A superplasticizer is preferably a new generation superplasticizer, for example a copolymer containing a polyethylene glycol as a grafted chain and carboxylic functions in the main chain such as a polycarboxylic ether. Sodium polycarboxylate polysulfonates and sodium polyacrylates can also be used. Phosphonic acid derivatives can also be used. The required amount of superplasticizer usually depends on the reactivity of the cement. The lower the reactivity, the lower the required amount of superplasticizer. To reduce the total amount of alkaline salts, the superplasticizer can be used as a calcium salt rather than as a sodium salt.

The mixing of the hydraulic composition can be carried out, for example, according to known methods.

According to one embodiment of the invention, the binder is prepared during a first stage, and any aggregates and water are added during a second stage.

The hydraulic composition used can be shaped to produce, after hydration and hardening, a shaped object for the field of construction. Objects shaped for the field of construction include, for example, a floor, a screed, a foundation, a wall, a partition, a ceiling, a beam, a worktop, a pillar, a bridge stack, a cinder block, a pipe, a pole, a staircase, a panel, a cornice, a mold, a road element (for example a curb), a roof tile, a covering (for example a road or a wall) or an insulating element (acoustic and / or thermal).

Dv90 is the 90th percentile of the particle size distribution, in volume, ie, 90% of the particles are smaller than or equal to Dv90 and 10% of the particles are larger than Dv90.

Particle size distributions and particle sizes of less than about 200 μm are measured using a Malvern MS2000 laser particle size analyzer. The measurement is carried out in ethanol. The light source consists of a red He-Ne laser (632 nm) and a blue diode (466 nm). The optical model is that of Mie and the calculation matrix is of the polydisperse type. The apparatus is calibrated before each working session using a standard sample (Sibelco C10 silica) with a known grain size curve.

The measurement is carried out with the following parameters: pump speed of 2300 rpm and agitator speed of 800 rpm. The sample is introduced so as to obtain an obscuration of 10 to 20%. The measurement is carried out after stabilization of the obscuration. Ultrasound is emitted at 80% for 1 minute to ensure deagglomeration of the sample. After about 30 seconds (to evacuate any air bubbles), a measurement is made for 15 seconds

PA14011 FR (15000 images analyzed). Without emptying the cell, the measurement is repeated at least twice to check the stability of the result and the evacuation of any bubbles.

All the measurements presented in the description and the ranges specified correspond to the average values obtained with ultrasound.

Particle size greater than 200 μm is generally determined by sieving. The moisture of a pozzolanic material, that is to say the water absorbed by the porosity or on the surface of the material, can be determined by heating, for example at a temperature of 100-110 ° C., of the pozzolanic material. while doing regular weighing, until there is no more mass loss.

In the present description, including the accompanying claims, the percentages are by mass unless otherwise specified.

The following non-restrictive examples illustrate exemplary embodiments of the invention.

EXAMPLES

The hydraulic composition tested was a standardized mortar according to the standard N F EN 196-1 of April 2006, the formulation of which is described below.

The standardized sand was a siliceous sand in accordance with the NF EN 196-1 standard of April 2006, whose supplier is Société Nouvelle du Littoral. The compositions tested in the examples all included 1350 g of sand.

The cement was a CEM I 52.5 N cement with a Blaine specific surface area of about 3390 cm 2 / g, from the Lafarge cement plant in Le Havre. The cement consisted of 2.4% by weight of gypsum, 1.6% by weight of anhydrite and 96% by weight of clinker which had the following chemical composition:

The total is not 100% because of minor elements not taken into account.

The pozzolanic material was: - a natural pozzolan from Blantyre having a Dv90 of about 13 pm and a reactive silica amount of about 39% by weight; a natural pozzolana from Rezina having a Dv90 of about 75 μm and a quantity of reactive silica of about 53% by weight; a natural pozzolan from Racos having a dv90 of about 17 μm and a quantity of reactive silica of about 59% by weight;

PA14011 EN

a natural pozzolan from Bulacan having a dv90 of approximately 33 μm and a quantity of reactive silica of approximately 37% by weight; a natural pozzolan from Songwe having a Dv90 of about 11 μm and a quantity of reactive silica of about 38% by weight; a natural pozzolana from St Bauzille having a Dv90 of about 38 μm and a quantity of reactive silica of about 66% by weight; a natural pozzolan from Bazian having a Dv90 of approximately 38 μm and a quantity of reactive silica of approximately 33% by mass; a natural pozzolana from Batangas having a Dv90 of about 29 μm and a quantity of reactive silica of about 44% by weight; a natural pozzolana from Banda Aceh having a Dv90 of about 44 μm and a quantity of reactive silica of about 34% by weight; a metakaolin having a Dv90 of approximately 40 μm and a quantity of reactive silica of approximately 46% by weight (Trade name: Argical 1200S, supplier: Imerys); and rice husk ash having a dv90 of about 61 μm and a reactive silica amount of about 90% by weight (Silpozz 4).

The mineral compound capable of releasing a cation was: - lime having a purity of 99% (Supplier: Aldrich); the same cement as that described above.

The pozzolanic material was treated according to the following protocol: put the pozzolanic material to be treated in the tank of an Eirich mixer; - add the treatment water; homogenize for 3 minutes at speed 1 (300 rpm); - add the mineral compound; homogenize for 3 minutes at speed 1; - Leave the pozzolanic material treated (in an airtight bag) to rest before using it.

After the rest period, the treated pozzolanic material was used to make a mortar.

The mortar was manufactured according to the protocol as described in standard NF EN 196-1 of April 2006. The spreads of the mortars obtained were determined by measuring the spread on the impact table (after 25 strokes) according to the ASTM C1437 standard, 5 minutes after mixing.

Example 1: Treatment of a pozzolan

The treatment method according to the present invention has been tested on several pozzolans. Tests 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19 were controls because these compositions included a pozzolan that had not been treated according to the method of the present invention.

Table 1 below shows the compositions tested and the results obtained for spreading at 5 minutes after mixing. Quantities are expressed in grams unless otherwise specified.

Table 1: Hydraulic compositions comprising pozzolans and spreads at 5 minutes after mixing

* mass percentage relative to the pozzolan mass According to Table 1 above, by comparing the control formulas (1, 3, 5, 7, 9, 11, 13, 15, 17 and 19) comprising a non-pozzolan treated according to the process of the present invention and formulas 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 comprising a pozzolan treated according to the process of the present invention, it is apparent that the treatment according to the The present invention makes it possible to improve the spreading at 5 minutes of a hydraulic composition comprising a pozzolan.

Example 2: Treatment of a metakaolin

The treatment method according to the present invention was tested on a metakaolin (Argical 1200S). Tests 1, 9 and 14 were controls because these compositions included a metakaolin which had not been treated according to the method of the present invention. Each of the compositions tested included 247.5 grams of cement and 135 grams of a siliceous filler (Trade name: C400, Supplier: Sibelco).

PA14011 EN

Table 2 below shows the compositions tested and the results obtained for spreading at 5 minutes after mixing. Quantities are expressed in grams unless otherwise specified.

Table 2: Hydraulic compositions comprising a metakaolin and spreads at 5 minutes after mixing

mass percentage relative to the mass of metakaolin According to Table 2 above, by comparing the control formulas (1, 9 and 14) comprising an untreated metakaolin according to the process of the present invention and the formulas 2 to 8, 10 to 13 and 15 to 17 comprising a metakaolin treated according to the method of the present invention, it is visible that the treatment according to the present invention makes it possible to improve the spreading at 5 minutes of a hydraulic composition comprising a metakaolin.

Example 3 Treatment of a Biomass Ash

The treatment method according to the present invention has been tested on biomass ash (rice husk ash). Tests 1 and 3 were controls because these compositions included rice husk ash that had not been treated according to the process of the present invention. Each of the compositions tested included 225 g of cement (Le Havre CEM I) and 135 g of a siliceous filler (C400).

Table 3 below shows the compositions tested and the results obtained for spreading at 5 minutes after mixing. Quantities are expressed in grams unless otherwise specified.

PA14011 EN

Table 3: Hydraulic compositions comprising rice husk ash (CCR) and spreads at 5 minutes after tempering

* mass percentage relative to the mass of rice husk ash According to Table 3 above, by comparing the control formulas 1 and 3 comprising an untreated rice husk ash according to the process of the present invention and respectively formulas 2 and 4 comprising a rice husk ash treated according to the process of the present invention, it is apparent that the treatment according to the present invention makes it possible to improve the spreading at 5 minutes of a hydraulic composition comprising an ash of rice husk.

Claims (2)

A method for treating a pozzolanic material comprising a step of contacting the pozzolanic material with a mineral compound capable of releasing a cation in solution, the mixture of the pozzolanic material and the inorganic compound comprising from 1 to 15% by mass water; the contact between the pozzolanic material and the mineral compound being carried out for at least 1 hour before the use of the pozzolanic material treated; and the amount of inorganic compound capable of releasing a cation in solution being from 0.5 to 15% by weight relative to the weight of pozzolanic material. 2- The method of claim 1, wherein the pozzolanic material is selected from natural or artificial pozzolans as described in NF EN 197-1 of February 2001 or in ASTM 595 chapter 8. 3- Method according to any one of the preceding claims, wherein the pozzolanic material is a metakaolin. 4. Process according to any one of the preceding claims, in which the inorganic compound capable of releasing a cation in solution is chosen from lime, potash, soda, cement kiln dusts, clinkers, cements and their mixtures. . 5. Process according to any one of the preceding claims, in which the bringing into contact is a mixture or co-grinding. 6- Processed pozzolanic material obtained by the process of any one of the preceding claims. 7. A method of manufacturing a hydraulic binder comprising the following steps: a) treating a pozzolanic material according to the method of any one of claims 1 to 5 to obtain a pozzolanic material treated; b) at least 1 hour after step a), placed in contact between a clinker and a treated pozzolanic material as obtained according to step a). 8- Method according to the preceding claim, wherein the amount of pozzolanic material treated is 5 to 75% by weight relative to the mass of binder. 9- A method of manufacturing a hydraulic composition, comprising a step of contacting water with a hydraulic binder as obtained according to the method of claim 7 or 8. 10- Method according to the preceding claim, in wherein the water / binder ratio is 0.2 to 1.