Method for protecting reinforcement of reinforced concrete structures during conservation of unfinished construction projects using migrating corrosion inhibitor

Abstract

FIELD: constructions.SUBSTANCE: methods for protecting reinforced concrete structures from corrosion of reinforcement during the period of long-term conservation of facilities whose construction has been suspended.Method which involves preparing the surface of reinforced concrete structures and applying a protective composition in the form of a migrating corrosion inhibitor (MCI) that does not form a film on the surface of the concrete. During preparation, the surface is zoned according to the degree of damage and humidity to determine the consumption of the MCI, the number of MCI application layers and the time interval between them, and the surface is cleaned. The application of MCI is carried out by a multi-layer saturated impregnation method with a total consumption of at least 0.5 l / m2. After application, control samples are installed on the structures in the form of concrete samples with reinforcement, simulating the composition and condition of the protective layer of the main structure, to monitor the concentration of MCI in them during the conservation period. If a minimum concentration of the active substance MCI is detected in the test samples, MCI is re-applied to the reinforced concrete structures.EFFECT: invention is aimed at extending the lifespan of load-bearing reinforced concrete structures of an unfinished construction project during the conservation period by 15-50 years without corrosion damage to the reinforcement to ensure the resumption of construction without large-scale repair work.3 cl, 5 dwg

Description

[0001] 1. Technical field

[0002] The invention relates to construction, specifically to methods for protecting reinforced concrete structures from reinforcement corrosion during long-term mothballing of facilities whose construction is suspended. The method prevents corrosive destruction of steel reinforcement caused by concrete carbonation, chloride penetration (from de-icing agents or the marine environment), and atmospheric exposure in the absence of permanent operational protection.

[0003] 2. State of the Art

[0004] Methods are known for protecting reinforcement using coatings based on migrating corrosion inhibitors (MIC), which are applied to the surface of concrete (e.g., Cortec MCI-2020, Sika FerroGard-903+, IFHAN MIK-80) / Alekseev S.N., Ratinov V.B., Rosenthal N.K., Kashurnikov N.M. Steel corrosion inhibitors in reinforced concrete structures. - Moscow: Stroyizdat, 1985 / [1]. The compositions penetrate through the concrete stone to the reinforcement and form a protective monomolecular layer on its surface, suppressing anodic and / or cathodic corrosion reactions.

[0005] A disadvantage of known methods for preserving unfinished construction projects is that they are designed for conditions of completed and operational structures. During preservation, structures often have high concrete moisture content, surfaces unprotected from the atmosphere, lack final water-repellent coatings, and are subject to temperature fluctuations. This reduces the effectiveness and predictability of migrating rebar corrosion inhibitors and their standard application methods.

[0006] A "Surface-Applied Corrosion Inhibitor" is known (Patent No. 2744612 C2 IPC C04 B 41 / 45 (2006.01)) which describes a sealant composition for a cementitious base and includes a non-aqueous mixture of a first silane and a second silane having a higher molecular weight than said first silane, and at least one corrosion inhibitor. Moreover, said corrosion inhibitor is soluble in silane, soluble in silane diluted with a solvent, and at least partially soluble in water.

[0007] A “Migrating corrosion inhibitor for steel reinforcement in concrete” is known (Patent No. 2413038 C1 C23F 11 / 00 (2006.01) in which the proposed composition, when applied to the surface of a reinforced concrete product or when added to a cement mortar used in repair work, is capable of migrating deep into the concrete stone and protecting the steel reinforcement of reinforced concrete structures already in use from corrosion.

[0008] "Migrating corrosion inhibitor for steel reinforcement in concrete" (Patent No. 2478734 C1 IPC C23F 11 / 00 (2006.01) and "Reinforcement corrosion inhibitor" (Patent No. 2527467 C2 IPC C04 B 24 / 18 (2006.01) are known, which determine the ratio of components of a salt of benzoic acid or substituted benzoic acid and a surfactant, additionally contain a salt of a dicarboxylic acid.

[0009] A significant drawback of these known corrosion inhibitors is that they do not contain a method of application and technology for using a migrating corrosion inhibitor of steel reinforcement for reinforced concrete structures during the conservation of unfinished construction projects.

[0010] A “Method for protecting and / or restoring a corroded metal surface and a coating composition obtained by this method” is known (Patent No. 2379320 C1 IPC C09D 5 / 08 (2006.01) C08L 63 / 04 (2006.01) B32B 15 / 092 (2006.01)) in which a resin based on Derakane 8084 polyesters is applied to the damaged surface as a primer layer, after drying, at least two layers of powder-bonded glass mat and three layers of surface veil are applied to the surface as a reinforcing layer, which are impregnated with a resin based on Derakane 411-350 polyesters, rolled with a roller, after drying, a protective coating is applied in the form of a wax topcoat based on isophthalic polyester resin.

[0011] However, this invention only applies to the protection of metal surfaces, such as oil product transportation tanks, and is not suitable for reinforced concrete structures of unfinished construction projects.

[0012] A method for applying a steel corrosion inhibitor is known (Patent No. 2446896 C2 IPC B05D 1 / 00 ​​(2006.01)), which describes the process of applying a corrosion inhibitor after preparing the inhibitor in a container using a circulation pump.

[0013] This method is only suitable for protecting steel structures from corrosion and can be used to protect overpasses, railway and road bridges and other metal structures and buildings.

[0014] 3. Disclosure of the invention

[0015] Technical task – creation of a method that ensures guaranteed long-term protection of the reinforcement of reinforced concrete structures under conditions of indefinitely long-term conservation of an unfinished construction project, taking into account the possible non-ideal state of the concrete and variable external conditions, using a migrating reinforcement corrosion inhibitor.

[0016] The technical result is an extension of the service life of the load-bearing reinforced concrete structures of the facility during the conservation period of the unfinished construction project by 15-50 years without corrosion damage to the reinforcement, which allows for the resumption of construction in the future without large-scale repair work.

[0017] The specified technical result is achieved in a method for protecting the reinforcement of reinforced concrete structures during the conservation of unfinished construction projects using a migrating corrosion inhibitor (MIC), including preparing the surface of reinforced concrete structures and applying a protective composition, according to the invention, a MIC that does not form a film on the surface of concrete is used as a protective composition, when preparing the surface of reinforced concrete structures, the surface is zoned according to the degree of damage and humidity to determine the consumption of MIC, the number of layers of application of MIC and the time interval between them, and cleaning the surface, while the application of MIC is carried out by a multi-layer saturated impregnation method with a total consumption of at least 0.5 l / m 2, and after application to the structures, control witness samples are arranged in the form of samples of concrete with reinforcement, simulating the composition and condition of the protective layer of the main structure, to control the concentration of MIC in them during the preservation period, and if a minimum concentration of the active substance MIC is detected in the witness samples, re-application of MIC to the reinforced concrete structures is carried out.

[0018] In a particular case, the implementation of the method for zones with cracks with an opening width of more than 0.3 mm is carried out, in addition to surface impregnation, by injecting the MIC composition into the body of the structure.

[0019] In another special case, the application of the MIC is carried out at a residual moisture content of the concrete that does not interfere with the capillary absorption of the composition.

[0020] This method is characterized by a combination of application methods (surface impregnation and injection into cracks / joints), staged monitoring of concrete moisture content, and the use of a migrating corrosion inhibitor as the primary and only protective agent during the preservation period. The migrating corrosion inhibitor is selected from among water-soluble compounds that do not form a film on the concrete, so as not to impede subsequent vapor permeability and adhesion to repair compounds upon resumption of construction and installation work.

[0021] 4. Brief description of drawings

[0022] The present invention is explained by graphic materials, which serve to clearly represent the sequence of operations and key technological features of the claimed method.

[0023] Fig. 1 - General flow chart (algorithm) for implementing the method. The diagram sequentially depicts the main stages: 1 - preparatory (inspection of structures, zoning, surface cleaning and local repairs if necessary), 2 - main (layer-by-layer application of the MIC, maintaining intervals between layers, injection) and 3 - control (marking, installation of witness samples, monitoring of the MIC concentration).

[0024] Fig. 2 - Schematic section of a fragment of a reinforced concrete structure illustrating the operating principle of the method. Shown: 1 - concrete surface; 2 - concrete body; 3 - steel reinforcement; 4 - protective layer of concrete; 5 - migrating corrosion inhibitor applied to the surface; 6 - direction of migration of molecules of the active substance of the inhibitor through capillaries and microcracks of the concrete to the surface of the reinforcement; 7 - protective mono- or polymolecular layer formed on the surface of the reinforcement.

[0025] Fig. 3 - Approximate zoning scheme of a typical reinforced concrete column or wall. The zones are marked with symbols: A - zone with normal concrete condition (MIC application by impregnation); B - zone with crack network (impregnation with increased consumption); C - zone with local damage to the protective layer and exposed reinforcement (preliminary repair, then impregnation); G - zone of the working joint or cold joint (MIC injection in addition to impregnation).

[0026] Fig. 4 - Schematic diagram of the control specimen (marker specimen) device. The specimen installed in the structure after treatment is shown: 8 - treated structure; 9 - control specimen (a small sample of concrete with reinforcement, simulating the composition and condition of the protective layer of the main structure); 10 - marking with information on the date of treatment and the type of MIC.

[0027] Fig. 5 - Dependence of the consumption of the MIC, the number of MIC application layers, and the time interval between MIC application layers on the zoning of the reinforced concrete structure.

[0028] 5. Implementation of the invention

[0029] The method for protecting the reinforcement of reinforced concrete structures during the conservation of unfinished construction projects using a migrating corrosion inhibitor is implemented in the following sequence:

[0030] 1) Preparatory stage.

[0031] A visual inspection (with instrumental assistance if necessary) and zoning of unfinished reinforced concrete structures based on their condition are conducted. Areas with visible cracks, chips, high humidity, defects, and exposed reinforcement are identified in accordance with Fig. 3.

[0032] Preparation of the surface of reinforced concrete structures. The concrete surface is cleaned of dirt, efflorescence, loose layers, and cement laitance. Medium-pressure water jetting (up to 180 bar) is used for cleaning. Ensure the surface is dry or slightly damp (not wet) for the layer-by-layer application of the MIK.

[0033] In areas with defects and exposed reinforcement, local repairs are performed if necessary. The reinforcement is cleaned of loose rust, then coated with an inhibitor (such as the same MIC) as a contact primer, and then the protective concrete layer is restored with a quick-setting repair compound.

[0034] 2) The main stage is the application of a migrating corrosion inhibitor to the surface of a reinforced concrete structure.

[0035] Apply the compound to the prepared surface using the infiltration method (saturated impregnation) - by repeated spraying or pouring with a roller. Apply 2-4 coats (3-4 coats on ceiling surfaces). Consumption is at least 0.5-0.7 l / m. 2 , but may be increased for high-density concrete. The interval between applications is from 30 to 120 minutes, depending on the temperature and absorbency. The number of layers, the total consumption of MIC, and the time interval between layers are determined in accordance with the application zone (Fig. 5). MIC application is carried out at a concrete and air temperature of +5°C to +40°C, with a forecast of no precipitation or frost for at least 12-24 hours after application and in accordance with the technical conditions for the MIC grade used.

[0036] 3) Control stage.

[0037] To monitor the effectiveness of the protection during the preservation period, concrete specimens with reinforcement are installed in specific areas of treated structures. At specified intervals (e.g., after 6, 12, and 24 months of preservation), core samples are collected in reinforced concrete structures treated with the MIK to a depth greater than the concrete protective layer to assess the penetration depth of the MIK and the condition of the reinforcement.

[0038] The test samples are removed and cut into equal parts (e.g. 1 cm each) and sent to the laboratory to determine the concentration of the active substance MIC in each part of the test sample using a chemical method.

[0039] If the minimum concentration of the active substance MIC is detected in the witness samples, the MIC is re-applied.

[0040] The surface of the structures is marked with warning signs about the treatment carried out with MIK, indicating the date of the treatment, the MIK grade used, the number of layers applied and the total consumption of MIK, the section number and zones of the reinforced concrete structure.

Claims

1. A method for protecting the reinforcement of reinforced concrete structures during the conservation of unfinished construction projects using a migrating corrosion inhibitor (MCI), including preparing the surface of reinforced concrete structures and applying a protective composition, characterized in that a MCI that does not form a film on the surface of concrete is used as a protective composition; when preparing the surface of reinforced concrete structures, the surface is zoned according to the degree of damage and humidity to determine the consumption of the MCI, the number of layers of application of the MCI and the time interval between them, and cleaning the surface; the application of the MCI is carried out by a multi-layer saturated impregnation method with a total consumption of at least 0.5 l / m 2, and after application to the structures, control witness samples are arranged in the form of samples of concrete with reinforcement, simulating the composition and condition of the protective layer of the main structure, to control the concentration of MIC in them during the preservation period, and if a minimum concentration of the active substance MIC is detected in the witness samples, re-application of MIC to the reinforced concrete structures is carried out.

2. The method according to paragraph 1, characterized in that for areas with cracks with an opening width of more than 0.3 mm, in addition to surface impregnation, an injection of the MIC composition into the body of the structure is used.

3. The method according to paragraph 1, characterized in that the application of the MIC is carried out at a residual moisture content of the concrete that does not impede the capillary absorption of the composition.

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