Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/04—Portland cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00034—Physico-chemical characteristics of the mixtures
  • C04B2111/00103—Self-compacting mixtures
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
  • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength

Definitions

• the invention relates to fast binder compositions based on a calcium salt, used for the manufacture of concrete parts and structures.
• quick binders for mortar or concrete is meant fast setting and hardening binders. Concretes using such binders in their compositions, once implemented, acquire important mechanical characteristics in the short term. They preferably have a compressive strength RC of at least 1 MPa at 4 hours for the fluid concretes and at least 1
• These concretes are fluid or self-compacting concretes (or self-compacting) and have a working time of 1 hour minimum to 2 hours maximum.
• the workability of the fluid concrete is measured by the subsidence height at the Abrams cone -or slump- value (according to the French standard NF P 18-451, of December 1981) and it is estimated that a concrete is fluid when this sag is at least 150 mm, preferably at least 180 mm.
• the workability of self-compacting concretes is generally measured from the "slumpflow", according to the procedure described in "Specification and Guidelines for Concrete Compacting Concrete, EFNARC, February 2002, pl9-23"; the value of the spread is greater than 650 mm for self-compacting concretes (and in general less than 800 mm).
• the invention relates to concretes, and more particularly to fluid or self-compacting concretes (or self-compacting), intended for the production of parts and works, whether they be prefabricated parts in the factory, or realizations on building sites, such as for example concrete sails, slabs, etc.
• FR-A-2810314 discloses a fast binder for self-compacting concrete comprising Portland cement, calcium aluminate, calcium sulfate, an accelerator and a retarder, and a superplasticizer polyphosphonate polyox type.
• this binder makes it possible to have a workability greater than 1 hour, to pump the concrete thanks to this self-compacting formula, while having high mechanical compressive strengths at 6 o'clock and at 24 o'clock, including at temperatures between 10 and 35 ° C.
• the applications described in this document are the urgent repair of works, the temporary support of tunnels, galleries, or other similar works. There is no mention of concrete veil application.
• US-P-3427175 discloses compositions comprising an accelerator system containing a calcium nitrite. This document also describes a cure at a temperature that is not compatible with the outside temperatures conventionally encountered on the sites.
• JP-A-2000281412 describes accelerator systems containing a calcium salt which is a sulphite or calcium sulphate, in combination with an organic adjuvant and a superplasticizer. It is stated that compressive strengths are obtained in relatively short times, but the data provided are only 24-hour data.
• GB-A-2033367 and GB-A2058037 disclose accelerator systems comprising calcium aluminate in admixture with calcium sulfate, a hydroxy acid (eg citric acid) and an inorganic salt (eg example nitrite or nitrate, sodium carbonate being indicated as preferred).
• EP-A-537872 discloses an accelerator system comprising a nitrite or nitrate, for example calcium in combination with a specific copolymer superplasticizer
• SIKA products in particular Sikaprise SC2
• GRACE products in particular Polarset, containing calcium nitrite, calcium nitrate (and bromide salts), a small amount of thiocyanate, and methyldiethanamylamine.
• MBT products in particular the products in combination, the Pozzolith NC 534 accelerator, the Glenium 3030 high-speed superplasticizer and the Delvo retarder.
• US20030127026 discloses an accelerator system comprising in combination: a polycarboxylate superplasticizer, an accelerator and a retarder.
• the accelerator may be chosen in particular from alkaline earth metal nitrites, thiocyanates, halides, and especially calcium salts of acids, for example formic acid, etc. No mixing of these components is described.
• a retarder is in particular a carboxylic acid.
• the flexural strength is indicated as at least 2.8 MPa and the compressive strength as at least 15 MPa, within 4 hours after casting, at a temperature of 10-38 ° C.
• the cementitious compositions described according to this invention have a workability maintenance time limited to a maximum of 30 minutes, a high cement content and low water / cement ratios of between 0.25 and 0.40.
• US20040149174 describes a system similar to that of the previous application, but in combination with a salt lowering the freezing point of the mixture.
• a polycarboxylate superplasticizer alkaline earth metal nitrites are cited
• an accelerator cited thiocyanates and halides
• a retarder is cited carboxylic acids.
• the examples do not specify the exact compounds used, nor do they provide information on the maintenance of the workability and the mechanical strengths obtained at 4 or 6 hours. They relate to concretes which are not fluid or self-compacting concretes. The properties have been studied at temperatures which are in some cases of the order of -1 ° C.
• the invention relates to a rapid binder comprising: cement; at least one superplasticizer; calcium nitrite; and - at least one formic derivative.
• the invention further relates to an accelerator system comprising at least one superplasticizer, calcium nitrite, and at least one formic derivative.
• the invention also relates to a concrete composition or wet mortar comprising a fast binder according to the invention wasted with water.
• the invention also relates to a method for preparing mortar or concrete by mixing fast binder according to the invention and aggregates with water, in particular implemented at a temperature less than or equal to 10 0 C.
• the invention provides a method of preparing concrete objects or mortar with double stripping in one day, said double stripping being implemented at a temperature less than or equal to 10 0 C. DESCRIPTION OF EMBODIMENTS OF THE INVENTION.
• the invention is based on a combination of additives containing at least one accelerator system.
• the accelerator system according to the invention comprises at least three elements, namely a calcium salt which is calcium nitrite, a specific organic adjuvant which is a formic derivative and a superplasticizer.
• Calcium salt is calcium nitrite.
• This salt is present in the composition of the accelerator in amounts which can vary from 50 to 90% by dry weight. In general, the amount is such that the amount of calcium nitrite in the final binder is between 0.5 and 10%, preferably between 1.5 and 5% by dry weight relative to the final binder.
• the formic derivative may be in aldehyde form; it is formaldehyde or formaldehyde (it being understood that the polymers, for example urea-formaldehyde, are not formic derivatives within the meaning of the invention insofar as there is no release of the monomer formol or formic acid or salt-) .
• the formic derivative may be in the form of formic acid optionally in saline form with an alkali metal or alkaline earth metal.
• the formic derivative may be formalin, formic acid or a salt form of an alkali or alkaline earth metal, or the bisulfite formol of an alkaline or alkaline earth metal, especially sodium bisulfite, or formaldehyde sulfoxide.
• an alkali or alkaline earth metal such as sodium formaldehyde sulfoxylate (available as rongalite ® ).
• Single or bisulfite aldehyde forms are preferred, although all other forms are usable.
• the formic derivative is present in the composition of the accelerator in amounts which may vary from 1 to 5% by weight. In general, the amount is such that the amount of the formic derivative, relative to the calcium nitrite salt, is between 1 and 10% of the amount of calcium nitrite, preferably between 2 and 5%. With respect to the weight of the final binder, the amount is such that the amount of the formic derivative is between 0.01 and 1%, preferably between 0.05 and 0.5% by weight.
• the superplasticizer is any superplasticizer used in industry, such as those defined in the European standard EN 934-2.
• superplasticizers which are of the polyox polyphosphonate or polysulphonate polyox type, or better still of the polyox polycarboxylate (PCP) type.
• PCP polyox polycarboxylate
• An example of a superplasticizer is that described in EP-A-537872, EP-A-663892, US20030127026 and US20040149174, incorporated herein by reference.
• An example of a superplasticizer is that obtained by polymerization: at least one ionic monomer phosphonic, sulfonic or carboxylic type, preferably carboxylic and preferably of (meth) acrylic type; and at least one monomer of the polyethylene glycol (PEG) (meth) acrylate type, in particular PEG methyl ether (in the terminal position), the molecular weight of which is for example between 100 and 10,000, preferably between 500 and 5000 and advantageously between 750 and 2000.
• the first monomer / second monomer molar ratio can vary widely, for example 75:25 to 45:55, preferably 65:35 to 55:45.
• one or more monomer (s) for example those chosen from: (a) acrylamide type, for example N, N-dimethylacrylamide, 2,2'-dimethylamino (meth) acrylate or its salts, 2 , 2'-dimethylaminoalkyl (meth) acrylate or its salts with the alkyl group and in particular ethyl and propyl, and in general any monomer containing an amine or amide type function;
• acrylamide type for example N, N-dimethylacrylamide, 2,2'-dimethylamino (meth) acrylate or its salts, 2 , 2'-dimethylaminoalkyl (meth) acrylate or its salts with the alkyl group and in particular ethyl and propyl, and in general any monomer containing an amine or amide type function;
• hydrophobic type for example C1-C18 alkyl (meth) acrylate, in particular methyl or ethyl.
• the amount of this third monomer may be between 5 and 25 mol% of the total monomers.
• a particular example of a superplasticizer used in the invention is that obtained by polymerization of 40 to 65% of (meth) acrylic acid, 25 to 40% of PEG methyl ether (meth) acrylate, in particular of molecular weight between 750 and 2000, and 5 to 25% of a monomer of type (a) or (b), in particular of type (a) and especially 2,2'-dimethylaminoalkyl (meth) acrylate.
• Another example is a polyox polycarboxylate containing from 10 to 30 mol% of N-methylol acrylimide or derivative.
• Superplasticizers are in a form that can vary from the liquid form to the solid form, through the waxy form.
• This superplasticizer is present in the composition of the accelerator system in amounts which can vary from 10 to 30% by weight, calculated from the dry extracts of the constituents of the system.
• the dosage of the superplasticizer relative to the binder is generally between 0.1 and 5% by weight (% calculated from the solids content of the superplasticizer), preferably between 0.1 and 2% by weight relative to the weight of the binder.
• a liquid superplasticizer in general there will be a quantity such that it will be present preferably from 1 to 10, preferably 2 to 7 1 / m 3 of the final mixed concrete mix.
• the binder or accelerator system may contain other components in addition to the above three compounds.
• the following compounds can be mentioned, alone or as a mixture:
• thiocyanate and / or calcium bromide, sodium or potassium will be used as co-accelerators of calcium nitrite.
• the amount of these other compounds associated with the accelerator system may represent, for example, up to 20% by weight of the calcium nitrite.
• the binder intended to form wet concrete generally comprises, relative to the dry weight of the binder: 99.5 to 90% of Portland cement; 0.5 to 10% of the accelerator system.
• the binder comprises: 99 to 95% of Portland cement;
• Portland cement is traditional and conforms to the families described in the European standard EN 197-1. It is possible, for example, to use a CEM1 52.5 N or R, CEM2 cement of type 32.5, 32.5 R, 42.5 or 42.5 R.
• the cement may be of the HRI (High Initial Strength) type.
• the Portland cement is a cement, preferably ground to a fineness of at least 4000 cm 2 / g.
• the soluble alkali content will preferably be less than 1%, advantageously less than 0.6%, by weight expressed as Na 2 O equivalent.
• the amount of C4AF is less than 8% by weight, advantageously less than 4%, and the amount of C3S of the starting clinker is greater than 60% by weight.
• the final amount of the accelerator system depends on the temperature of use of the concrete, the exact method of implementation, the level of resistance to obtain, etc. Moreover, this quantity is adjusted according to the final quantities of the various components in the final concrete mix.
• the concrete comprising this superplasticizer is advantageously fluid or self-compacting (self-compacting).
• additives which may be used, mention may be made of: air entraining agents, defoaming agents, corrosion inhibitors, shrinkage reducing agents, fibers, pigments, rheology modifying agents, precursors of hydration, water-soluble polymers, pumpability assistants, alkali reducing agents, reinforcing agents, water-repellent compounds, and mixtures thereof.
• the compounds of the final concrete composition can be used in the following order: according to a first embodiment, all the components of the accelerator system are added from the start, during the mixing of the concrete, at the plant concrete; the cement and the complete accelerator system are lost, namely calcium nitrite, formic derivative and superplasticizer.
• Mixing at the concrete plant can be done either in a fixed mixer or in a truck mixer when it is used directly as a mixer.
• the invention therefore relates to the process in which all the components are introduced as soon as the fast binder is mixed with the aggregates and the water.
• the calcium nitrite will be added later than the other components of the accelerator system, for example at the level of the truck-top, before the departure of the concrete plant, or during the central path / site, or at the site just before casting.
• the invention therefore also relates to the process in which the calcium nitrite is introduced after kneading the other components of the fast binder with the aggregates and the water.
• the times selected for this delayed introduction can be from 10 to 90 minutes, preferably 20 to 60 minutes after mixing with the other components of the accelerator system, superplasticizer and / or formic derivative.
• the invention therefore also relates to the process in which the calcium nitrite is introduced from 10 to 90 minutes, preferably from 20 to 60 minutes later.
• cement cement, accelerator system components
• the ratio by weight of water effective on dry binder (E / C ratio) is generally between 0.45 and 0.65.
• the final composition comprises conventional aggregates (sands, gravel and / or pebbles).
• the constituents of the final composition have a size less than or equal to 20 mm, preferably less than or equal to 10 mm in the case of self-compacting concretes (or self-compacting concretes).
• the composition can thus be pumped easily.
• the dry weight ratio of aggregates to binder is generally between 4 and 5.
• the concrete compositions according to the invention are easy to implement and are of low cost. They have a suitable rheology, preferably involving a working time (after mixing) of a minimum hour and an hour and a half to a maximum of two hours and a very fast hardening.
• the workability of these concretes according to the invention is generally between 1 and 2 hours.
• workability time is meant the fluidity maintenance time, which corresponds to the setting start time; in general the slump values (fluid concrete) are at least 15cm, preferably at least 18cm.
• the concrete according to the invention may be a fluid concrete, especially a fluid concrete having at 90 minutes a sag of at least 15 cm, preferably at least 18 cm. It can have a compressive strength, from 4 hours after the end of mixing, of the order of at least IMPa and preferably at least 2 MPa, and at least
• the concrete according to the invention may also be a self-consolidating concrete, especially a self-compacting concrete having at 90 minutes a spread greater than 650 mm. It can have a compressive strength, from 5h from the end of mixing, of the order of at least IMPa and preferably at least 2MPa, and at least 12MPa at 24, measured on cylindrical specimens of dimension 16cmx32cm . As the mixing is implemented in a spin truck, the time is counted from the moment of introduction into the top of the last component of the concrete composition.
• the fast binder for fluid or self-compacting concretes (self-compacting) of the invention is easily pumpable or castable, especially without vibration in the case of self-compacting concretes, which makes it, for example, particularly suitable for the manufacture of concrete sails.
• the invention is particularly aimed at making concrete sails, by casting and / or pumping.
• the invention is useful for the manufacture of concrete sails at outside temperatures in particular between -5 ° C and 30 0 C, in particular below 10 0 C. It will be recalled that a concrete veil is defined in masonry as "any wall vertical and solid concrete banché ".
• the invention also provides a manufacturing method, in particular concrete sails, by double stripping daily at temperatures less than or equal to 10 0 C, in particular using the accelerator system according to the invention.
• the invention according to another embodiment, provides such a method that allows to cast two concrete sails in a day, even at low temperatures.
• the compositions according to the invention thanks to their fast setting properties even at low temperature, achieve this double stripping. It has also been found that it is possible, as long as the compositions are fast and maintain their workability, to break with the traditional approach, and to proceed even at low temperatures, to double-stripping.
• Example 1 illustrates the invention without limiting it.
• a mortar having the following composition (parts in kg / l, 5m 3 ) is prepared:
• the E / C ratio is 0.49.
• compositions comprising a superplasticizer which is Glenium 27 from MBT.
• the following compositions are tested:
• composition Al according to the invention has, at 90 min, a spread significantly greater than that obtained with the compositions Bl and Cl, with a difference of about 50 mm for a spread of more than 270 mm.
• the mechanical strengths of 5h30mn maturity are also significantly improved. Moreover, for the composition Al, the mechanical strength at 4 hours is 2.5 MPa.
• the composition A2 according to the invention has, at 90 min, a spread significantly greater than that obtained with the compositions B2, C2 and D2, with a difference of at least 80mm for a spread of 300 mm.
• the mechanical compressive strengths with a maturity of 5h30mn are also significantly improved with respect to the compositions B2 and C2, and of the same order as that of D2, despite a duration of maintaining the spread more than doubled.
• a concrete having the following composition (parts in kg / m 3 ) is prepared:
• the E / C ratio is 0.5.
• compositions are prepared:
• This example gives the results obtained with self-compacting (compacting) concrete using FBS (sodium formaldehyde bisulfite) and the effect of this on the rheology and the acquisition of resistances.
• the temperature is 20 ° C.
• Example 5 The tests were carried out in mortar with the following formula (parts in kg / m 3 )

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• Ceramic Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
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• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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• 2005
  • 2005-06-10 EP EP05291257A patent/EP1731491A1/de not_active Withdrawn
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