FR2858821A1 - Anti-corrosion compound for the preventive and curative treatment of metal reinforcement enclosed in mortar and concrete - Google Patents

Abstract

A compound with an anti-corrosion base has an association with an anti-rust agent with: (a) a polyfunctional derived phosphoric complex under the form of amine salts, which exacerbate the anti-rust properties; (b) a bipolar solvent which facilitates spreading and improves the anti-rust protection. Independent claims are also included for: (a) an anti-corrosion composition made up of this compound with an addition of a tensio-active anionic defloccuating, fluidising, plastifying derivative in the form of amine salts or mixed sodium/amine salts allowing the production of an anti-corrosion product for preventive treatments; (b) an anti-corrosion composition made up of this compound with an addition of an additive containing a fluoro-carbon surfactant lowering the superficial and interfacial tensions, notably in the form of amine or lithium salts to obtain an anti-corrosion product for curative treatments.

Description

ANTI-CORROSION COMPOSITIONS FOR TREATMENTS

  METAL FRONTS INCLUDED IN MORTAR AND CONCRETE

  The subject of the present invention is an anti-corrosion composition intended for the treatment of reinforcing metal reinforcement of mortars and concrete, constituted by a basic anti-corrosion combination to which is added a specific additive for the preventive treatments and another specific additive for curative treatments.

  Corrosion of reinforcing metal reinforcement of mortars and concretes is a serious problem that has long been of concern to specialists and is particularly present in mountain regions where melt salts (calcium chloride) are used during the winter; or around the sea where there is a saline atmosphere.

  Two distinct cases must be taken into consideration: - the preventive anti-corrosion treatment, which consists in protecting the rebars against the installation and development of rust phenomena leading to corrosion damage.

  This treatment is applied to fresh materials during their preparation.

  If at the time of their introduction these materials have good rheological characteristics (fluidity, spreading, plasticity) they will better coat the metal frames; these in alkaline medium will be better protected. A fortiori if a basic anticorrosive combination is combined with a rheology additive additive itself having a good anti-rust propensity.

  the curative anti-corrosion treatment which consists of interventions on old mortars or concretes, which present points of corrosion, most often due to the appearance of micro-cracks in the materials, and which serve as vectors for the oxygen and other agents giving rise to rust, then to the development of corrosion phenomena. It is therefore necessary to reduce or even eliminate them, and to ensure good protection against new oxidative aggressions.

  The intervention on hardened old materials requires a good control of penetration, diffusion, migration and the path of the active solution through the micro-channels, to the site to be treated where there is corrosion.

  It has been found that both of these problems can be solved by combining the same basic anti-corrosion combination with specific additives depending on whether preventive treatment or curative treatment is being sought.

  The articulation of the invention is thus the following: a base anti-corrosion composition to which is associated: a rheology agent additive for the preventive treatments an additive wetting agent spreading, diffusion, migration for curative treatments

DESCRIPTION

  A. Basic anti-corrosion combination al. The use of reducing agents such as, for example, sodium nitrite as anticorrosive agent for steels has been well known for a long time.

  In the context of the present invention, it has been found that the anti-rust properties of Sodium Nitrite solutions are exacerbated and very substantially improved when they contain, together with nitrite, one or more complexing agents, which are polyfunctional active against metal ions, in the form of amine salts, in particular, inter alia, salts of dimethyl amino ethanol, ethyl hexylamine, cyclohexylamine, morpholine, TEA, amino-methylene phosphonic acid 1-hydroxy-ethylene-1,1-diphosphonic acid, hexamethylene-diamine tetra (methylphosphonic acid), diethylene triamine penta (methylphosphonic acid), and in particular ethylene diamine tetra ( methyl phosphonic):

O O

  ## STR2 ## ## STR2 ##

O O

  And also: Nitrilotriacetic acid: N- (CH2-COOH) 3 in the form of amine salt including those indicated above.

  In general, the percentage of the complexing agent is between 3 and 10%, expressed as active material, relative to sodium nitrite.

  This synergistic effect results in a significant increase in anti-rusting power. Thus, comparative tests on metal fibers have shown that an aqueous solution containing 99.3% water and 0.65% sodium nitrite + 0.05% of the dimethyl amino ethanol salt of ethylene diamine tetra (methyl phosphonic acid) anti-rust virtually equivalent to an aqueous solution of 98.8% water and 1.2% sodium nitrite.

  a2. The passivation of steels by phosphoric acid and its derivatives is also well known for a long time.

  In the context of the invention, it has also been found that the combination of a phosphoric ester of general formula:

O

o e OH

RO RO

  (or R is an aliphatic or branched, hydrocarbon chain containing from four to eighteen carbon atoms, which chain may also be polyoxyethylenated, and comprise from three to nine units / EO in the form of an amine salt, in particular those indicated below. before in paragraph a1, and a polyfunctional complexing agent, phosphonate in the form of a salt of amines and in particular the dimethylaminoethanol salt of ethylene tetra (methylphosphonic acid) with a ratio of 1-0.1, had antirust 30 to 35% higher than that of the phosphoric ester alone, at the same dosages of use (1%).

  a3. In the context of the invention it has been found that if at the two bases (a1-a2) described above, a bipolar film-forming solvent is added, their spreading is substantially improved, and a homogeneous continuous film is formed which is fixed on the metal surfaces, thus improving their rust protection.

  According to the invention, this film-forming solvent is constituted by dimethyl esters of succinic, glutaric, and adipic diacids used alone, or as a mixture, and in particular by a 20/60/20 mixture of: CH3-OOC-CH2-CH2 --- COO CH3 succinic acid methyl diesters CH3-OOC --- CH2-CH2-CH2 --- COO CH3 glutaric acid methyl diesters CH3-OOC --- CH2-CH2-CH2-CH2-- -COO CH3 diesters methyl adipic acid whose distillation range is 195-225 C, and the surface tension, 35.5 dynes / cm.

  The basic anti-corrosion combinations claimed are composed of: - 60 to 75% of a reducing agent such as sodium nitrite - 20 to 10% of a polyfunctional complexing agent phosphonate amine salt - 20 to 15% of a bipolar film-forming solvent such as the methyl diester of a diacid The 60 to 75% of sodium nitrite can be replaced by 60 to 75% of an amine salt of a phosphoric ester, the other constituents remaining unchanged.

  On the other hand, the amine salts used according to the invention are obtained by leaving free an excess of amine. It maintains on the treatment site an alkaline amine atmosphere, having good anti-rust protection properties, especially with ethyl 2 hexylamine, and cyclohexylamine which form with water, always present, azeotropic.

  In anticorrosive, preventive and curative compositions, the level of amine left free is between 2 and 10%.

  B. Basic anti-corrosion additives to obtain the product for preventive treatment These are products that improve the rheological characteristics of the fresh materials in order to obtain a better coating of the metal reinforcements.

  These adjuvants are anionic derivatives, dispersing, deflocculating, plasticizing and fluidizing surfactants which, according to the invention, are used in the form of amine salts, which gives them a propensity for the anti-rust effect, such as: Lignosulfonates of amines, and inter alia lignosulfonate triethanolamine, dimethyl amino ethanol, cyclohexylamine, or ethyl 2 hexylamine.

  Polynaphthalene sulphonate in the form of amine salt, in particular from those mentioned above.

  Polymelamine formol sulfonate of amines among others of those already indicated above.

  Polymers, Copolymers, Terpolymers, most often acrylic, polyethoxylated polycarboxylates (PCP), in the form of sodium salts or sodium / amine mixed salts. These products (5th generation) are called in the field of application of hydraulic mortars and concretes: Superplasticizer Superfluidifier (SPSF) They are strongly adsorbed on the surfaces of cement grains and fine elements and cause their deflocculation, dispersion This results in a significant improvement of the rheological characteristics of the pasta of the fresh materials, facilitating their installation.

  The level of these specific adjuvants used separately or in a mixture, in the anti-corrosive preventive solution is such that at the dosage of the use thereof, it corresponds to 0.15 to 0.5% (expressed as active ingredient) of adjuvant relative to the weight of the cement used.

  The anti-corrosion compositions for preventive treatments claimed include: - 30 to 40% of the base anti-corrosion combination - 70 to 60% of anionic surfactant derivative, in the form of an amine salt and / or Polymer (SPSF) in the form of sodium or mixed Sodium / amine salts.

  C. Base anti-corrosion additives for obtaining the curative treatment product 40 These are products for wetting, spreading, penetrating, diffusing and tracking anti-corrosive solutions. .

  c.1 Surfactants lowering surface and interfacial tensions.

  The importance of the wetting mechanisms and the spreading of an aqueous solution on the surface of a solid are known. These depend on the connection angle at the solid-liquid-air boundaries. The WASHBURN law gives the speed of penetration of a liquid into a capillary; while the DUPRE equation and the HARKINS propositions make it possible to address the coefficients of spreading and adhesion tension.

  The knowledge of these physical phenomena, allows by the use of appropriate surfactants, to control the problems of diffusion, spreading and routing of the active anti-rust solutions, through micro-structures corroded hardened mortars and concretes.

  According to the invention, the curative anti-corrosion formulations comprise at least one fluorocarbon surfactant, most often anionic.

  These have exceptional surface properties which lead to lowering the surface tension of an aqueous solution at 0.1% o (0.1 per thousand) below 20 dynes / cm. These fluorocarbon surfactants correspond to the following general formulas: F (CF 2 -CF 2) x linked to various groups such as: - CH 2 -CH 2 -SO 3 M -sulfonate - ethoxyl (CH 2 -CH 2 -O) xH -ethoxyl Phosphate (CH 2 -CH 2 -O) y P- (OH), - carboxylic sulfide CH2CH2-S-CH2-CH2-OOOH or x = 1 to 10 y = 1 to 2 z = 2 to 1 y + z = 3 units M = metal: Sodium-Lithium-NH4- or Amine And in Particularly in the context of the invention will be used: F (CF2-CF2) X CH2-CH2-0) y P- (OH), in the form of amine salts, inter alia the following amines: Dimethylamino Ethanol, Ethyl2 Hexylamine , Cyclohexylamine, Morpholine, TEA or alternatively: F (CF 2 CF 2) x CH 2 -CH 2 -S-CH 2 -CH 2 -COO Li whose surface tension in aqueous solution at 0.02% is 20 dynes / cm. These two products also have a propensity for the anti-rust effect.

  The anti-corrosion compositions for claimed remedial treatments comprise: 95 to 99% of the base anti-corrosion combination; 5 to 1% of a fluoro carbonaceous surfactant in the form of an amine or lithium salt.

  C2. A polar solvent promoting the diffusion, the migration and the path through the micro-fissures of the materials of the anti-corrosive active solutions, to reach the sites where corrosion reigns.

  According to the invention, use will be made of: Dimethylsulfoxide (DMSO) CH3 CH3 \ S / O2858821 which has a vapor pressure at 20 C of 0.417 m / m Hg Or, and Dimethylformamide CH3 NHCO CH3 whose surface tension at 25 C is 35 dynes / cm Or, - Ethyl Lactate CH3 CH COO CH2 - CH3 1

OH

  These products are used alone or in mixture.

  The anti-corrosion compositions for curative treatments claimed comprise: - 70 to 80% of the base anti-corrosion combination - 30 to 20% of a polar solvent, such as Dimethylsulfoxide promoting their diffusion and migration.

[EXAMPLES

  The examples mentioned below illustrate the invention without however being limited to these formulations alone.

Examples 1 and 2:

  In Table 1/5 presented below, are mentioned Example 1 and Example 2 which correspond to products, obtained according to the invention, intended for 5o preventive anti-corrosion treatments. 10

TABLE N 115

Claims (3)

ANTI-CORROSION PRODUCTS FOR PREVENTIVE TREATMENT Example 1 Example 2 COMPONENTS Example Example N 1% N 2% 1n z Sodium nitrite 8.75 z - Alkyl phosphoric ester DMAE salt 8.50 Ethylene diamine tetra methyl phosphonate E2HA 1 , 50 eTD m Nitrilo Triacetate DMAE 2.00 oz δ - Di methyl esters of dibasic acids 2.00 2.00 (mixture) - E2HA lignosulfonate 5.00 - DMAE lignosulfonate 25.00 to z cl) - Acrylic terpolymer / polycarboxylate wz mixed salt Na / E2HA 30.00 H. Acrylic / polycarboxylate terpolymer mixed salt Na / DMAE 10.00 <1- n. - Alcohol (c8-c18) polyoxyhexylene 0.25 1.00 - E2HA (Ethyl 2 Hexylamine) 5.00 DMAE (dimethylamino ethanol) 5.00 - Water 47.50 46.50 They are used at the time of the preparation of mortars or fresh concrete. Most often by introduction into the mixing water at percentages included - depending on the cement - between 1 and 1.5% of the weight of cement. As shown by the results reported in Table 2/5 below, these formulations confer good rheological characteristics (plasticity, fluidity) to the fresh mortars, which then allows a good coating of the metal reinforcements, and later within the hardened materials , to ensure a good anti-rust prevention (see table 3/5 below). The rheological characteristics of the fresh materials (see Table 2/5 below) are evaluated in the laboratory, by the comparative measurements of the slumps on mortar, according to the NF EN 12706 standard, notably by the practical provisions of the P3 tests (self-leveling). ). The principle is the measurement of the spreading diameter of a cake of a given volume, always identical. 8 TABLE N 2/5   COMPARATIVE MEASUREMENTS OF SPREADING Example 1 Example 2 WITNESS Example 1 - Example 2 - Additive% / cement dosage 0 1.3 1 - Slump at T 0 (cm) 5.5 14 12.5 - Slump at T 60 '(cm) / 12 10.5 20 - Slump at T 120 '(cm) / 11 9.5 Composition of mortar (%) ^ Cement CPA 52.5 27 ^ Sand0.1 -0.5m / m 53 É Filler limestone 0.1 m / m 15 ^ Chalk (Omyalviolette) 5 É Water + Additive For the assessment of rust protection (see Table 3/5 below) the experimental method used in the laboratory is severe. It allows for accelerated comparative results. 9 TABLE N 3/5   ASSESSMENT OF THE RUST PROTECTION WITH THE   Examples 1 and 2 for the preventive treatment MORTIER MORTAR MORTAR with MORTAR Example 1 with Example 2% additive / cement 0 1.3 1.3 Exam 7 days x 0 0 days x 0 0 days xx 0 0 90 days xxx 0 0 days xxx 0 0 days xxx 0 0 days xxx 0 0 210 days xxx 0 0 240 days xxx 0 0 270 days xxx 0 0 300 days xxx 0 0 330 days xxx 0 0 1 year xxx 0 0 0: no rust spots x: some scattered rust spots 45 xx: more important rust (50%) xxx: generalized rust 5o We operate on mortar samples, frustoconical (diameter less than 4.2 cm, sup.5.3 cm, height 9.5 cm) obtained with 200 g of dry mortar tempered with water + additive = 40 g.   The composition of the mortar is identical to that indicated for the above slump tests: except limestone filler 0.1 mlm reduced to 10% (instead of 15%) + 5% steel fibers. 10   The products of Examples 1 and 2 were used at 1.3% of the weight of cement, ie for the 200 g test tube: 200 x 27% x 1.3% = 0.7 g added to 39.3 g of water.   The specimens kept in a humid chamber (95%) are demolded at thirty-six hours, and immediately immersed (immersed height 2 cm) in a 1% solution of Cl2Ca.   A sufficient quantity (about 6 kgs) of mortar is prepared so that it is possible to break (hammer), a first time after seven days of immersion, two test pieces, and then, two test pieces are broken every month for one year, and we appreciate the evolution of rust on the metal fibers included. Examples 3 and 4:   Their respective composition is shown in Table 4/5 below. TABLE N 4/5   CORROSION PRODUCTS FOR CURING TREATMENT EXAMPLE 3 Example 4 CONSTITUENTS Example Example   N 3 N 4% Io (1) Sodium nitrite 8.70 (2) Alkyl phosphoric ester DMAE salt 9.00 (3) Ethylene diamine DMAE tetra methyl phosphonate 2.60 (4) DMAE Nitrilo Triacetate 3.00 (5) Di-methyl esters of diacids (mixture) 2.50 2.50 (6) Li fluoro carbon carboxylate surfactant 0.30 co (7) DMAE fluorocarbon phosphate surfactant 0.30 (8) DMSO Dimethyl sulphoxide 4, 2 (9) DMFA Dimetyl formamide 4.50 w l (10) DMAE Dimetyl Amino ethanol 6.00 8.00 Ω <(11) Water 75.60 72.70 <I-O They are intended for anti-corrosion treatments curative: hardened concrete, old, corroded.   Evaluation of the Penetration, Diffusion, Migration, Flow of the Products of Examples 3 and 4 The tests are carried out on 4 × 4 × 16 cm samples, obtained with a mortar having the following composition: 450 g NF cement (CEMI 52.5, N CE CP2 NF) 5 1350 g CEN sand 225 g water Mixing, molding, demolding and preservation were carried out in accordance with Standard NF EN 1861.   The test pieces, after demolding, are stored for 28 days immersed in water and left for six hours in the open air before the migration test.   This was done compared to water (control test). For each product, 200 g of aqueous solution containing 1% of anti-corrosion agent (Example 3 / Example 4) are produced.   The water and the two solutions are put in three identical containers and a 4x4x16 strip is deposited vertically in each container, the height of the submerged part of each of the test pieces is two centimeters.   After forty-eight hours the height at which the liquids have been absorbed on each test piece is measured. The tests are done in duplicate, and it is found that the absorption heights are identical from one test to another.   Table 5/5 below reports the comparative results with formulations in which one or two constituents have been removed, which are supposed to influence the migration of the solution. TABLE N 5/5   EXAMPLE 3 EXAMPLE 4 FOR CURATIVE TREATMENT   APPRECIATION OF THE POWER OF MIGRATION   TEST LIQUID City water (control) Solution 1% Example 3 Solution 1% Example 4 Solution 1% Example 3 without components (6) and (8) 50% Solution 1% Example 3 without components (8) and (5) Solution 1% Example 3 without component (3) AT = total absorption 16 cm 40 HEIGHT OF MIGRATION   AFTER 48 HOURS cm 16 cm AT 16 cm AT cm 11 cm 14 cm Assessment of the anti-corrosion action Simple tests were carried out in the laboratory under the following severe conditions: Aqueous solutions of 200 g each containing 1% of inhibitors Example 3 and 4.   This solution is placed in a test container with 400 g of metal fibers (steel).   The whole of the fibers are agitated to wet well. These are removed after five minutes of contact with the test solution, and then left in the open air (TC 20 C + 2). Results: A control test carried out with town water alone reveals two days the first rust spots. These are generalized on the third day.   On the fifth day, all the fibers are covered with rust. For the metal fibers treated with the solutions (1%) of the inhibitors Example 3 and Example 4, no rust spots were observed on the fibers after one year of free storage in the laboratory.   Claim 1 Anti-corrosion base combination for reinforcing metal reinforcements included in mortars and concretes, characterized in that it consists of the combination of Sodium Nitrite of between 60 and 75% of a polyfunctional phosphonate salt complexing agent. an amine of between 10% and a di-acid methyl ester of between 15%.   Claim 2 A base anti-corrosion combination characterized in that it comprises an alkyl phosphoric ester and / or an alkyl ethoxy phosphoric ester in the form of amine salts of between 60% and 75%, a polyfunctional phosphonate salt complexing agent of amine salt ranging from 10% and a di-methyl ester of a diacid of between 15%.   Claim 3 Anti-corrosion composition according to Claim 1 and / or Claim 2, characterized in that an additive anionic anionic surfactant defoaming agent, plasticizer, is added to the basic anti-corrosion combination of between 40% and 30%. of amine salt or sodium / amine mixed salts of between 60 and 70% which makes it possible to obtain an anti-corrosion product intended for preventive treatments.   Claim 4 Anti-corrosion composition according to Claim 1 and / or 2 and Claim 3, characterized in that an additive of polymers, in particular polycarboxylates in the form of sodium salt, is added to the basic anti-corrosion combination of between 40% and 30%. sodium or mixed salt sodium / amine, deflocculant, plasticizer, plasticiser between 60 and 70 0/0 to obtain an anti-corrosion product for preventive treatments.   Claim 5 Composition according to Claim 1 and / or 2, characterized in that an additive containing a fluorocarbon-based surfactant is added to the basic anti-corrosion combination of 95% to 99% of the surface and interfacial tensions, in particular in the form of salt. of amines or lithium between 1 5% to obtain an anti-corrosion product for curative treatments.   A composition according to claims 1 and / or 2 and claim 4, characterized in that an additive containing a polar solvent promoting its diffusion and migration is added to the basic anti-corrosion combination of between 70% and 80%. other Dimethyl Sulfoxide between 30%, to obtain an anti-corrosion product for curative treatments.   2858821 14 Claim 7 Composition according to the set of claims 1 to 7 characterized in that they contain an excess of amine derivative of 2 to 10%.   Claim 8 4 0 Application of the compositions according to claims 1, 2, 3, 4 and 7 characterized in that they are used for preventive anticorrosion treatments, reinforcing metal reinforcements included in mortars and concretes.   A claim 9 Application of the compositions according to claims 1, 2, 5, 6 and 7 characterized in that they are used for anticorrosive healing treatments, reinforcing metal reinforcements included in the mortars and concretes.