Preparation method and application of a repairing mortar with steel bar rust conversion function

Abstract

The application discloses a kind of repair mortar preparation method with steel bar rust conversion function and application, belong to repair mortar technical field, including the following steps: one, rust inhibitor intercalation hydrotalcite, disodium hydrogen phosphate, sodium phytate are proportioned dry mixing, grinding to particle size≤50 μm;Two, cement, mineral admixture, aggregate, compound rust conversion agent are added to mixer according to formula proportion, dry mixing 3-5 minutes, make it fully mixed evenly;Three, water reducing agent, polymer emulsion are added to water, stir evenly, and prepared additive solution;Four, under the condition of continuous stirring, additive solution is slowly added to dry mixed material obtained in step two, stir 5-10 minutes, until the uniform, non-caking repair mortar is obtained.The application can effectively fill the corrosion site of reinforced concrete, restore the integrity of structure, significantly improve the durability of reinforced concrete in complex harsh environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of repair mortar, in particular to a repair mortar with steel rust conversion function and its preparation method and application. BACKGROUND

[0002] In the maintenance and repair process of concrete structures, steel corrosion is a key factor that cannot be ignored. Once the steel is corroded, its volume will expand due to oxidation reaction, which will exert a huge pressure on the surrounding concrete, causing damage such as cracking and spalling. In some extreme cases, this damage may endanger the stability and safety of the structure, and even cause the failure of the entire structure. Therefore, it is extremely important to research and develop a repair mortar that can effectively repair cracks and spalling and protect the internal steel from further corrosion. Such repair mortar not only prolongs the service life of the concrete structure, but also significantly reduces maintenance costs, with significant practical application value and economic benefits.

[0003] Currently, the main methods for treating steel corrosion are traditional repair methods, such as chiseling off the corroded part of the concrete, removing rust from the steel, and then re-pouring concrete or using ordinary repair mortar for repair. However, these methods have many shortcomings, such as tedious rust removal process, high labor intensity, high cost, and ordinary repair mortar does not have the function of converting steel rust, which cannot fundamentally solve the problem of steel re-corrosion, and the durability of the repaired structure is still difficult to be effectively guaranteed. Therefore, a new repair mortar is urgently needed, which not only can efficiently fill cracks, but also can effectively convert the rust layer on the surface of the steel, forming a protective barrier to prevent further corrosion of the steel. At the same time, this repair mortar should simplify the construction process, reduce the damage to the original concrete structure, and reduce the construction difficulty and time cost, so as to better adapt to the fast and efficient needs of modern construction engineering. SUMMARY

[0004] The purpose of the present application is to provide a repair mortar with steel rust conversion function and its preparation method and application, which aims to solve the technical defects of existing repair mortar in steel repair, simplify the construction operation process, improve the durability of reinforced concrete in complex and harsh environments, and realize efficient repair of concrete structures.

[0005] To achieve the above purpose, the present application provides a repair mortar with steel rust conversion function, which comprises the following components by mass fraction:

[0006] Cement: 30-50 parts, the cement is ordinary portland cement with a strength grade not lower than 42.5;

[0007] Mineral admixture: 10-20 parts, the mineral admixture includes one or more of fly ash, slag powder, silica fume;

[0008] Aggregate: 60-150 parts, the aggregate is quartz sand with a particle size of 0.1-2 mm;

[0009] Compound rust conversion agent: 5-10 parts, the compound rust conversion agent is a compound mixture of organic phosphate, phosphate and rust inhibitor intercalated hydrotalcite;

[0010] Water reducing agent: 0.2-1.5 parts, the water reducing agent is a polycarboxylic acid high-performance water reducing agent;

[0011] Polymer emulsion: 10-15 parts, the polymer of the polymer emulsion is an acrylate or epoxy resin polymer;

[0012] Water: 25-35 parts.

[0013] Preferably, in the above-mentioned repair mortar with steel bar rust conversion function, the compound rust conversion agent includes the following components by mass fraction:

[0014] Rust inhibitor intercalated hydrotalcite (INT-LDHs): 30-50 parts;

[0015] Disodium hydrogen phosphate (Na2HPO4): 20-40 parts;

[0016] Sodium phytate: 20-30 parts.

[0017] Preferably, in the above-mentioned repair mortar with steel bar rust conversion function, the INT-LDHs is obtained by intercalating modification of Mg-Al-CO3 type or Zn-Al-CO3 type hydrotalcite with small-molecule organic migration type rust inhibitor.

[0018] Preferably, in the above-mentioned repair mortar with steel bar rust conversion function, the polymer emulsion is a fast-hardening acrylate or epoxy resin polymer emulsion.

[0019] Preferably, the preparation method of the repair mortar with steel bar rust conversion function as described above comprises the following steps:

[0020] Step one: dry mix INT-LDHs, Na2HPO4 and sodium phytate in proportion, and grind to a particle size of ≤50 μm;

[0021] Step two: add cement, mineral admixture, aggregate and compound rust conversion agent to the mixer according to the formula proportion, dry mix for 3-5 minutes, and make them fully mixed and uniform;

[0022] Step three: add water reducing agent and polymer emulsion to water, stir until uniform, and prepare an additive solution;

[0023] Step four: slowly add the admixture solution to the dry mixture obtained in step two under continuous stirring, stir for 5-10 minutes until a uniform, non-caking repair mortar is obtained, and the water-binder ratio in the wet mixing stage is controlled to be 0.25-0.35.

[0024] Preferably, the application of the repair mortar with the steel bar rust conversion function as described above comprises the following steps:

[0025] Step one: clean the surface of the corroded steel reinforced concrete structure to remove loose, peeled concrete and rust and other impurities;

[0026] Step two: apply or spray the prepared repair mortar to the steel bar corrosion site and the surrounding concrete surface, with a thickness of 10-50mm;

[0027] Step three: maintain the repair mortar after application or spraying, and the curing time is not less than 7 days, keeping the surface of the repair mortar wet.

[0028] Preferably, the repair mortar is used for repairing existing steel reinforced concrete structures in chloride ion erosion or carbonation environments.

[0029] Therefore, the repair mortar with the steel bar rust conversion function prepared by the preparation method and application has the following beneficial effects:

[0030] (1) synergistic rust inhibition: the repair mortar of the present application is prepared by compounding INT-LDHs, sodium phytate and Na2HPO4, which fully utilizes the characteristics of sodium phytate and Na2HPO4 in promoting the regeneration of the passivation film, and at the same time utilizes the adsorption of INT-LDHs to the free chloride ions on the surface of the steel bar and its vicinity to enhance the stability of the passivation film, effectively prevent the further corrosion of the steel bar, and improve the durability of the building structure.

[0031] (2) efficient repair: the repair mortar can effectively fill the corrosion site of the steel reinforced concrete, restore the integrity of the structure, significantly improve the durability of the steel reinforced concrete in complex and harsh environments, realize the re-repair function of the steel bar, and fill the gap in the field of steel bar repair in the prior art.

[0032] (3) simple process: the preparation method is simple, the operation process is easy to control, the raw materials are widely available, the cost is low, and it is suitable for large-scale industrial production. In the application process, since steel rust removal is not required, the operation process is greatly simplified, the construction time and cost are reduced, and it is conducive to promoting its application and popularization.

[0033] The technical solutions of the present application will be further described in detail through the following examples. DETAILED DESCRIPTION

[0034] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0035] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two.

[0036] It should also be noted that the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the goods or devices including a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such goods or devices. Without more limitation, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the goods or devices including the element.

[0037] The present application provides a repairing mortar with a steel bar rust conversion function, which comprises the following components in parts by mass:

[0038] Cement: 30-50 parts, the cement is ordinary portland cement with a strength grade not lower than 42.5;

[0039] Mineral admixture: 10-20 parts, the mineral admixture includes one or more of fly ash, slag powder and silica fume;

[0040] Aggregate: 60-150 parts, the aggregate is quartz sand with a particle size of 0.1-2 mm;

[0041] Compound rust conversion agent: 5-10 parts, the compound rust conversion agent is a compound mixture of organic phosphate, phosphate and rust inhibitor intercalated hydrotalcite;

[0042] Water reducing agent: 0.2-1.5 parts, the water reducing agent is a polycarboxylic acid high-performance water reducing agent;

[0043] Polymer emulsion: 10-15 parts, the polymer of the polymer emulsion is an acrylate or epoxy resin polymer;

[0044] Water: 25-35 parts.

[0045] Specifically, the cement provides the basic strength and bonding performance of the repair mortar; the mineral admixture improves the workability, durability and microstructure of the repair mortar; the aggregate enhances the volume stability and strength of the repair mortar; the rust conversion agent is a compound mixture of organic phosphate, phosphate and rust inhibitor intercalated hydrotalcite, which can chemically react with rust to convert rust into a stable complex and prevent further corrosion of the steel bar; the water reducing agent is a polycarboxylic acid high-performance water reducing agent, which can ensure the fluidity of the repair mortar, reduce the water consumption, improve the strength and durability, and improve the physical structure and internal stress of the hardened cement paste, reduce the overall elastic modulus, reduce the water consumption, and improve the internal capillary pores of the hardened cement paste.

[0046] To further optimize the above technical solution, the rust conversion agent comprises the following components in mass fraction:

[0047] rust inhibitor intercalated hydrotalcite (INT-LDHs): 30-50 parts;

[0048] disodium hydrogen phosphate (Na2HPO4): 20-40 parts;

[0049] sodium phytate: 20-30 parts.

[0050] It should be noted that the rust inhibitor intercalated hydrotalcite (INT-LDHs) applied in concrete can release the rust inhibitor INT while adsorbing and solidifying the free chloride ions in the concrete, reducing the enrichment of chloride ions on the surface of the steel bar and the corrosion rate of the steel bar; the disodium hydrogen phosphate (Na2HPO4) can be used for surface treatment of the steel bar and surface conversion of rust, and the Fe 2+ reacts with disodium hydrogen phosphate: 3Fe 2+ + 2HPO4 2- → Fe3(PO4)2↓ + 2H + The reaction product can deposit on the surface of the steel bar and form a passivation film, achieving regeneration of the passivation film and effectively inhibiting corrosion of the steel bar; sodium phytate can react with iron ions on the surface of the steel bar to form a chelate of ferric phytate in an alkaline environment, and is adsorbed on the surface of the steel bar to form a protective film, helping to achieve re-passivation of the steel bar and inhibit corrosion.

[0051] To further optimize the above technical solution, the INT-LDHs are Mg-Al-CO3 type or Zn-Al-CO3 type hydrotalcite modified by small molecule organic migration type rust inhibitor intercalation.

[0052] To further optimize the above technical solution, the polymer emulsion is a fast-hardening type of acrylic ester or epoxy resin polymer emulsion.

[0053] For further optimization of the above technical solutions, the preparation method of the repair mortar with the steel bar rust conversion function as described above comprises the following steps:

[0054] Step one: dry mix INT-LDHs, Na2HPO4 and sodium phytate in proportion, and grind to a particle size of ≤50 μm;

[0055] Step two: add cement, mineral admixtures, aggregates and compounded rust conversion agent to the mixer according to the formula proportion, dry mix for 3-5 minutes, and fully mix and uniformize them;

[0056] Step three: add water reducing agent and polymer emulsion to water, and stir to prepare an additive solution;

[0057] Step four: under continuous stirring, slowly add the additive solution to the dry mixed material obtained in step two, stir for 5-10 minutes, and obtain uniform and lump-free repair mortar, wherein the water-binder ratio in the wet mixing stage is controlled to be 0.25-0.35.

[0058] For further optimization of the above technical solutions, the application of the repair mortar with the steel bar rust conversion function as described above comprises the following steps:

[0059] Step one: clean the surface of the corroded steel reinforced concrete structure, and remove loose, peeled concrete and rust and other impurities;

[0060] Step two: apply or spray the prepared repair mortar to the steel bar rusted part and the surrounding concrete surface, and the thickness is 10-50 mm;

[0061] Step three: maintain the repair mortar after application or spraying, and the maintenance time is not less than 7 days, and the surface of the repair mortar is kept wet.

[0062] For further optimization of the above technical solutions, the repair mortar is used for repairing the existing steel reinforced concrete structure in a chloride ion erosion or carbonization environment.

[0063] In order to more clearly and specifically introduce the preparation method and application of the repair mortar with the steel bar rust conversion function provided by the embodiments of the present application, the following will be described with reference to specific embodiments.

[0064] Embodiment 1

[0065] Preparation of repair mortar: Select cement 40 parts (select strength grade 42.5 ordinary Portland cement), mineral admixture (fly ash and silica ash mixed in a ratio of 1:1) 15 parts, quartz sand with particle size of 0.1-2mm 100 parts, compound rust conversion agent 8 parts, polycarboxylate superplasticizer 1 part, acrylic ester polymer emulsion 12 parts, water 30 parts. Among them, the compound rust conversion agent is composed of 40 parts of rust inhibitor intercalated hydrotalcite (INT-LDHs, Mg-Al-CO3 type hydrotalcite modified by small molecule organic migration type rust inhibitor intercalation), 30 parts of disodium hydrogen phosphate, 30 parts of sodium phytate. Put INT-LDHs, disodium hydrogen phosphate and sodium phytate into the grinding equipment in proportion, dry mix and grind to a particle size of ≤50μm. Put cement, mineral admixture, quartz sand and treated compound rust conversion agent into the mixer, dry mix for 4 minutes to ensure that the materials are fully mixed and uniform. Mix the water reducer and polymer emulsion in water, stir well to make an admixture solution. Under the condition of continuous stirring of dry mixed materials, slowly add the admixture solution, stir for 8 minutes until a uniform and lump-free repair mortar is obtained. The water-binder ratio in the wet mixing stage is controlled to be 0.3.

[0066] Application in building structure repair:

[0067] Cleaning the rusted part: Select a concrete structure where the steel bar is corroded due to chloride ion erosion, clean the surface of the corroded steel reinforced concrete structure, and carefully remove loose, peeled concrete and rust and other impurities with tools.

[0068] Apply repair mortar: evenly apply the prepared repair mortar to the steel rusted part and the surrounding concrete surface with a spreading tool, and control the thickness of the spreading to be 30mm.

[0069] Curing: After the spreading is completed, cover the surface of the repair mortar with plastic film, and regularly spray water to keep the surface of the repair mortar wet, and the curing time is 10 days.

[0070] After maintenance, the steel bars in the repaired part were detected, and it was found that a dense passivation film was formed on the surface of the steel bars. Through electrochemical test method, the corrosion potential and polarization resistance of the steel bars were measured, and the results showed that compared with the steel bars without using the repair mortar, the corrosion potential was obviously positive shift, and the polarization resistance was significantly increased, indicating that the corrosion rate of the steel bars was greatly reduced. This is because the INT-LDHs adsorbed on the surface of the steel bars, which enhanced the stability of the passivation film, and sodium phytate and sodium hydrogen phosphate promoted the regeneration of the passivation film, effectively preventing the further corrosion of the steel bars, which reflected the good synergistic rust inhibition effect and improved the durability of the building structure. After observing the repaired concrete structure, the repair mortar was closely combined with the original concrete without cracks, falling off and other phenomena, and the steel bar corrosion part was effectively filled, and the integrity of the structure was restored. The load test results of the repaired structure showed that its bearing capacity met the design requirements, and the durability in complex and harsh environment was significantly improved, which successfully realized the re-repair function of the steel bars, filled the part of the existing technology in the field of steel bar repair, and the whole process from preparation to construction application was simple and easy to control. In the preparation process, the raw materials were well mixed, and the equipment requirement was not high; during construction, there was no need for complex rust removal treatment of the steel bars, which reduced the construction process and saved a lot of construction time and cost. Compared with the traditional repair method, the construction efficiency was improved by about 30%, and the cost was reduced by about 20%, which was suitable for large-scale industrial production and popularization and application.

[0071] Example 2

[0072] Preparation of repair mortar: select cement 35 parts (ordinary portland cement with strength grade 42.5), mineral admixture (slag powder) 12 parts, quartz sand with particle size of 0.1-2mm 80 parts, complex rust conversion agent 6 parts, polycarboxylate high-performance water reducing agent 0.5 parts, epoxy resin polymer emulsion 10 parts, water 28 parts. The complex rust conversion agent is composed of 35 parts of rust inhibitor intercalated hydrotalcite (INT-LDHs, Zn-Al-CO3 hydrotalcite modified by small molecule organic migration type rust inhibitor), 35 parts of sodium hydrogen phosphate and 30 parts of sodium phytate. According to the preparation steps of example 1, the complex rust conversion agent is first dry mixed and ground, and then the dry mixed materials, preparation of admixture solution and wet mixing are carried out in turn, and the water-binder ratio is controlled to be 0.28 in the wet mixing stage.

[0073] Application in building structure repair:

[0074] Cleaning of corrosion part: for a concrete structure where the steel bars are corroded due to carbonization, the loose concrete and rust on the surface of the corroded steel bar concrete structure are cleaned.

[0075] Spraying repair mortar: the prepared repair mortar is sprayed to the steel bar corrosion part and the surrounding concrete surface by spraying equipment, and the spraying thickness is 20mm.

[0076] Curing: After the spraying is completed, water is sprayed by a spraying device for timed curing, and the curing time is 7 days.

[0077] The repaired steel bars are detected, and the linear polarization resistance method is used to monitor the corrosion of the steel bars, and the results show that the corrosion rate of the steel bars is obviously reduced. In the carbonization environment, the components in the repair mortar play a synergistic role, effectively inhibiting the corrosion of the steel bars and protecting the performance of the steel bars, providing a guarantee for the long-term stability of the building structure. The appearance of the repaired concrete structure is flat, and the repair mortar is firmly bonded with the original concrete. Durability tests are performed on the repaired structure, such as impermeability tests, and it is found that the impermeability performance is greatly improved compared to before repair, indicating that the repair mortar can effectively repair the damage caused by carbonization and improve the durability of the structure in the carbonization environment. During preparation, the raw materials are mixed uniformly, and the preparation process is stable. In terms of application, the spraying construction method is more efficient, and the damage to the original concrete structure during construction is small, reducing the construction cost, which reflects the advantages of the technology in practical engineering application, and is conducive to wide application in the field of building repair.

[0078] Therefore, the repair mortar with steel bar rust conversion function prepared by the method has the following advantages:

[0079] (1) Synergistic rust prevention: the repair mortar of the present application is prepared by compounding INT-LDHs, sodium phytate and Na2HPO4, which fully utilizes the characteristics of sodium phytate and Na2HPO4 in promoting the regeneration of passivation film, and utilizes the adsorption of INT-LDHs on the surface of steel bars and free chlorine ions nearby to enhance the stability of the passivation film, effectively prevent the further corrosion of the steel bars, and improve the durability of the building structure.

[0080] (2) Efficient repair: the repair mortar can effectively fill the corrosion parts of the reinforced concrete, restore the integrity of the structure, significantly improve the durability of the reinforced concrete in complex and harsh environments, realize the re-repair function of the steel bars, and fill the gap in the field of steel bar repair in the prior art.

[0081] (3) Simple process: the preparation method is simple, the operation process is easy to control, the raw materials are widely available, and the cost is low, which is suitable for large-scale industrial production. In the application process, since rust removal of the steel bars is not required, the operation process is greatly simplified, the construction time and cost are reduced, and the application and promotion of the present application are facilitated.

[0082] It should be pointed out finally that the above examples are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A repair mortar with steel rust conversion function, characterized in that, By mass, it includes the following components: Cement: 30-50 parts, wherein the cement is ordinary Portland cement with a strength grade of not less than 42.5; Mineral admixtures: 10-20 parts, wherein the mineral admixtures include one or more of fly ash, slag powder, and silica fume; Aggregate: 60-150 parts, wherein the aggregate is quartz sand with a particle size of 0.1-2mm; Compound rust converter: 5-10 parts, wherein the compound rust converter, by mass parts, includes the following components: rust inhibitor intercalated hydrotalcite: 30-50 parts; Disodium hydrogen phosphate: 20-40 parts; Sodium phytate: 20-30 parts; Water-reducing agent: 0.2-1.5 parts, wherein the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent; Polymer emulsion: 10-15 parts, wherein the polymer of the polymer emulsion is an acrylate or epoxy resin polymer; Water: 25-35 parts.

2. The repair mortar with steel rust conversion function according to claim 1, characterized in that, The rust inhibitor intercalated hydrotalcite is prepared by intercalation modification of Mg-Al-CO3 type or Zn-Al-CO3 type hydrotalcite with a small molecule organic migration type rust inhibitor.

3. The repair mortar with steel rust conversion function according to claim 1, characterized in that, The polymer emulsion is a fast-setting acrylate or epoxy resin polymer emulsion.

4. A method for preparing a repair mortar with steel rust conversion function as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Dry mix the rust inhibitor intercalated hydrotalcite, disodium hydrogen phosphate, and sodium phytate in a certain proportion, and grind them until the particle size is ≤50μm; Step 2: Add cement, mineral admixtures, aggregates, and compound rust converter to the mixer according to the formula ratio, and dry mix for 3-5 minutes to ensure thorough and uniform mixing; Step 3: Add the water-reducing agent and polymer emulsion to water, stir well, and prepare an admixture solution; Step 4: While continuously stirring, slowly add the additive solution to the dry mixture obtained in Step 2, and stir for 5-10 minutes until a uniform, lump-free repair mortar is obtained. During the wet mixing stage, control the water-cement ratio to be 0.25-0.

35.

5. The application of a repair mortar with steel rust conversion function as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Clean the surface of the corroded reinforced concrete structure to remove loose, peeling concrete and impurities such as rust; Step 2: Apply or spray the prepared repair mortar to the rusted steel bars and the surrounding concrete surface, with a thickness of 10-50mm; Step 3: Curing of the applied or sprayed repair mortar for at least 7 days, keeping the surface of the repair mortar moist.

6. The application according to claim 5, characterized in that, The repair mortar is used for the repair of existing reinforced concrete structures in environments subject to chloride ion corrosion or carbonization.