KR102581530B1 - Composition for Concrete Surface Repair And Concrete Section Recovery And Method for Repairing Concrete Structures Using the Same - Google Patents

Abstract

The present invention relates to a repair material composition for concrete surface repair and cross-sectional restoration that not only has high compressive strength after construction but also has excellent salt resistance, and a repair method for concrete structures using the same. The repair material for concrete surface repair and cross-sectional restoration according to the present invention The composition includes a binder containing blast furnace slag cement and polymer including blast furnace slag fine powder, calcium sulfoaluminate (CSA), lime, anhydrous gypsum (CaSO ₄ ), calcium aluminate cement (CAC), or Portland cement; And for 100 parts by weight of the binder, 5 to 10 parts by weight of magnesium oxide (MgO) reinforcing fibers with nanostructures formed on the surface, 5 to 10 parts by weight of aluminum oxide (Al ₂ O ₃ ) powder, sodium hydroxide, water glass and water. It may contain 40 to 60 parts by weight of a three-component alkaline activator, 0.3 to 1.0 parts by weight of a thickener, and 10 to 20 parts by weight of filler.

Description

Repair material composition for concrete surface repair and section recovery and method for repairing concrete structures using the same {Composition for Concrete Surface Repair And Concrete Section Recovery And Method for Repairing Concrete Structures Using the Same}

The present invention relates to a repair material composition for concrete surface repair and cross-section restoration and a method for repairing concrete structures using the same, and more specifically, to a method of repairing concrete structures using the same. More specifically, the present invention relates to fine powder of blast furnace slag including calcium sulfoaluminate (CSA), lime, anhydrous gypsum (CaSO ₄ ), and calcium. Concrete surface repair and cross-section restoration using blast furnace slag cement and polymer made by mixing aluminate cement (CAC) or Portland cement as a binder, and containing magnesium oxide reinforcing fibers and/or magnesium oxide reinforcing fibers with nanowires formed on the surface. It relates to a repair material composition and a method for repairing concrete structures using the same.

After construction, the durability and usability of reinforced concrete structures deteriorate in the long term due to chemical corrosion such as salt damage, neutralization, and alkaline aggregate reaction, as well as corrosion and expansion of the reinforcing bars due to water infiltration. If the deterioration of these structures continues, there is a risk that the structure will eventually collapse, so there is a need for continuous management and repair.

Delamination of the surface of a structure or the occurrence of initial defects or cracks facilitates the movement of deterioration factors and accelerates the progress of deterioration. Therefore, to ensure the safety and performance of reinforced concrete structures, repair and reinforcement are performed in the early stages of deterioration to suppress further deterioration. There is a need to improve durability.

Therefore, after removing the concrete part containing deterioration factors such as delamination or peeling of the cross-section of the structure due to deterioration of concrete, corrosion of rebar, or other causes, filling or spraying cross-section repair material to restore the cross-section to its original performance and form. It is common to carry out repairs after construction.

In general, concrete section repair mortars are made of binders such as cement, blast furnace slag fine powder, fly ash, metakaolin, and silica fume, powdered polymer resins such as urethane resin, acrylic resin, and polyester resin, fillers such as glass powder, and fine aggregate, as well as hardeners. It consists of additives such as , fluidizer, and thickener. In the past, a large amount of Portland cement was used in section repair mortars, but due to its lack of chlorine ion penetration resistance, three types of blast furnace slag fine powder (powder degree 3,500~4,500㎠/g), fly ash, and silica fume were mixed to improve chemical resistance. , long-term strength is secured.

Recently, as the problem of heavy metal leaching from cement and the problem of carbon dioxide emissions from the cement firing process have been pointed out, various ways to reduce the amount of cement used have been researched, and ways to use blast furnace slag as a cement substitute for concrete cross-section repair mortar have also been researched. It is becoming.

Blast furnace slag cement is manufactured by mixing and pulverizing Portland cement (or clinker), gypsum, and blast furnace slag. The blast furnace slag cement manufactured in this way has the disadvantage of slow hardening and low initial strength compared to ordinary cement.

In addition, the concrete section repair composition using conventional blast furnace slag cement does not perfectly bond with the existing concrete structure, and the mismatch between the two materials causes moisture to penetrate into the connection area, causing secondary damage. do. In addition, in Korea's environment where the temperature difference between seasons is large, there is a problem that there is a large difference between the connection parts by season due to the difference in thermal expansion coefficient.

In addition, conventional concrete cross-sectional repair compositions have a problem in that it is difficult to suppress salt damage and deterioration of concrete structures due to the corrosion of reinforcing bars caused by chloride.

Republic of Korea Patent No. 10-1384788 Republic of Korea Patent No. 10-1119893 Republic of Korea Patent No. 10-2251021 Republic of Korea Patent No. 10-2150666

The present invention is to solve the above problems, and the object of the present invention is to provide a repair material composition for concrete surface repair and cross-sectional restoration that not only has high strength after construction but also has excellent bonding power with the concrete structure and salt resistance, and a concrete structure using the same. To provide a repair method.

The repair material composition for concrete surface repair and cross-sectional restoration according to the present invention to achieve the above object includes blast furnace slag fine powder, calcium sulfoaluminate (CSA), lime, anhydrous gypsum (CaSO ₄ ), and calcium aluminate cement (CAC). or a binder containing blast furnace slag cement and polymer containing Portland cement; And for 100 parts by weight of the binder, 5 to 10 parts by weight of magnesium oxide (MgO) reinforcing fibers with nanostructures formed on the surface, 5 to 10 parts by weight of aluminum oxide (Al ₂ O ₃ ) powder, sodium hydroxide, water glass and water. It may include 40 to 60 parts by weight of a three-component alkaline activator, 0.3 to 1.0 parts by weight of a thickener, and 10 to 20 parts by weight of a filler.

The magnesium oxide (MgO) reinforcing fiber is made by immersing magnesium metal in the form of fibers with a length of 5 to 20 mm and a diameter of 0.2 to 1.0 mm in a solution of oxalic acid in methanol or ethanol for a certain period of time to form a surface. After forming a nanostructure by the reaction of magnesium ions (Mg ²⁺ ) and C ₂ O ₄ ^2- ions, a protrusion-shaped magnesium oxide (MgO) nanostructure is formed on the surface through heat treatment at 300-500°C. It may be made of fiber.

The magnesium oxide (MgO) reinforcing fiber may be pretreated by firing at a temperature of 700 to 1000°C before being mixed with the binder.

The repair method for concrete structures of the present invention is,

A first step of removing impurities, laitance or deteriorated areas from damaged areas of the concrete structure;

The second step of applying primer to the concrete structure;

A third step of applying the repair material composition to the concrete structure in a primer-applied state or repairing the damaged area in case of cross-sectional damage; and,

A fourth step of applying a repair material composition or applying a durability-improving surface coating agent to the surface of the damaged area in the event of cross-sectional damage;

may include.

When performing surface repairs on the surface of a concrete structure, in the first step, efflorescence or spalling on the surface is removed by grinding, washed with high-pressure water, dried, and then a penetrating alkali reducing agent is applied to the carbonated concrete. Performed sequentially,

When cross-sectional restoration is performed due to severe deterioration of the concrete structure due to delamination, spalling, salt damage, neutralization, etc. of the concrete structure, in the first step, the deteriorated area is removed by chipping and foreign substances are removed through high-pressure water washing. After drying, the process of applying a penetrating alkaline reducing agent to the carbonated concrete is sequentially performed.

When performing the above-mentioned cross-sectional restoration, if reinforcing bars are exposed in the deteriorated concrete structure area, additional operations of removing rust of the reinforcing bars and applying a rust preventive to the reinforcing bars may be performed.

In the repair material composition for concrete surface repair and cross-section restoration of the present invention, magnesium oxide (MgO) reinforcing fibers mixed with a binder and an alkali activator act to significantly increase compressive strength, and at the same time, magnesium oxide (MgO) reinforcing fibers The formation of hydrotalcite, which has a Mg-Al bonding structure, can be promoted within the repair material by the reaction between aluminum oxide (Al ₂ O ₃ ) and the ion exchange effect of hydrotalcite produced within the repair material can produce chloride. Provides the effect of effectively suppressing infiltration.

In addition, by replacing most Portland cement with cementless cement containing blast furnace slag and calcium sulfoaluminate (CSA), it is eco-friendly, exhibits superior initial and late strength compared to existing products, and generates ettringite during the product hydration reaction. This suppresses the occurrence of cracks due to drying shrinkage, which is the biggest problem with existing repair products, and has the effect of maximizing durability.

In addition, the penetrating alkali reducing agent used in the repair method of concrete structures according to the present invention has the effect of penetrating into neutralized concrete, maximizing alkali recovery and improving the surface strength of concrete.

In addition, the surface coating agent used in the repair method of concrete structures according to the present invention uses a network acrylic emulsion as a binder, which improves chemical resistance and abrasion resistance by modifying the linear acrylic emulsion into a three-dimensional network structure through re-crosslinking. , inorganic fillers with submicron-sized particles and various admixtures are applied to further improve durability against external deterioration environments. Manufactured in a one-component form, no separate mixing process is required before use, and drying and curing times are reduced. There is also the effect of drastically shortening the construction period.

Figure 1 is a flowchart explaining a method of surface repair of a concrete structure using a repair material composition for concrete surface repair and cross-section restoration according to the present invention.
Figure 2 is a flowchart explaining a method of cross-sectional restoration of a concrete structure using a repair material composition for concrete surface repair and cross-sectional restoration according to the present invention.
Figure 3 is a view showing magnesium oxide (MgO) reinforcing fibers constituting the repair material composition for concrete surface repair and cross-section restoration according to the present invention.
Figure 4 is an SEM photograph showing an enlarged nanostructure of magnesium oxide (MgO) reinforcing fibers constituting the repair material composition for concrete surface repair and cross-section restoration according to the present invention.
Figure 5 is a graph showing TD/DTG results for examples and comparative examples of the repair material composition for concrete surface repair and cross-section restoration according to the present invention.

The repair material composition for concrete surface repair and cross-section restoration according to embodiments of the present invention and the repair method of concrete structures using the same will be described in detail. Since the present invention can be subject to various changes and can have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Additionally, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. Meanwhile, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

The repair material composition for concrete surface repair and cross-section restoration according to the present invention includes blast furnace slag fine powder, calcium sulfoaluminate (CSA), lime, anhydrous gypsum (CaSO ₄ ), and calcium aluminate cement (CAC); And a binder containing a polymer is mixed with magnesium oxide (MgO) reinforcing fibers with nanostructures formed on the surface and aluminum oxide (Al ₂ O ₃ ) powder, and the composition includes an alkali activator, thickener, and filler to create concrete. It is designed to be applied to damaged areas of the structure. It generates ettringite during the product's hydration reaction, suppressing the occurrence of cracks due to drying shrinkage, which is the biggest problem with existing products, maximizing durability, and preventing the oxidation. The creation of hydrotalcite in the repair material can be promoted through the reaction between magnesium (MgO) reinforcing fibers and aluminum oxide (Al ₂ O ₃ ) powder.

Preferably, the repair material composition for concrete surface repair and cross-section restoration includes 5 to 10 parts by weight of magnesium oxide (MgO) reinforcing fibers with nanostructures formed on the surface, based on 100 parts by weight of the binder containing blast furnace slag cement and polymer, Aluminum oxide (Al ₂ O ₃ ) powder is 5 to 10 parts by weight, a three-component alkaline activator consisting of sodium hydroxide, water glass and water is 40 to 60 parts by weight, thickener is 0.3 to 1.0 parts by weight, and filler is 10 to 20 parts by weight. It may be composed of a mixed composition.

Blast furnace slag cement contains blast furnace slag as _the largest component by weight, _and contains calcium _{sulfoaluminate (} CSA), lime, anhydrous gypsum (CaSO ₄ ), and calcium aluminate cement (CAC) are included as additional ingredients. At this time, part of the calcium aluminate cement (CAC) can be replaced with ordinary Portland cement.

Looking at the ingredients of blast furnace slag cement in detail, 45-65% by weight of blast furnace slag, 5-8% by weight of lime, 5-15% by weight of anhydrous gypsum, 5-15% by weight of calcium sulfoaluminate (CSA), water reducing agent or highly fluidized. It may contain 0.3 to 2.5% by weight, and the balance is calcium aluminate cement (CAC).

Ettringite, which is produced by the hydration reaction of blast furnace slag cement, is a needle-shaped crystal and has a fairly large volume, so it exhibits some expansion in the initial stage of hydration. As a result, it has excellent properties with almost no sinking or drying shrinkage, which are problems with general Portland cement. has

Potentially hydraulic blast furnace slag is hydrated by adding anhydrous gypsum (CaSO ₄ ), slaked lime (Ca(OH) ₂ ), or quicklime (CaO), which are stimulants. In the present invention, calcium sulfoaluminate (CAS) is added to promote hydration more actively to promote hardening and significantly increase initial strength. At this time, the calcium sulfoaluminate (CAS)-lime-anhydrous gypsum mixture not only promotes the development of strength of blast furnace slag, but also generates ettringite hydrate (3CaO·Al ₂ O ₃ ·CaSO ₄ ·2H ₂ O) in the early stages of hydration and drying. This suppresses the occurrence of cracks due to shrinkage.

The calcium sulfoaluminate (4CaO·3Al ₂ O ₃ ·SO ₃ ) includes limestone as the CaO component, bauxite or an inorganic material with Al ₂ O ₃ as the Al ₂ O ₃ component, and gypsum as the SO ₃ component. , raw materials mixed so that Cm (lime saturation ratio = C-0.7(F+T+S')/1.87S+0.55A) is more than 0.60 and A/S' (aluminum water sulfate ratio) is in the range of 2.0 to 4.5. It is characterized in that it is manufactured by firing at a temperature of 1,200 to 1,500 ° C. (Here, C: CaO2% by weight, F: Fe2O3% by weight, T: TiO2% by weight, S': SO3% by weight, S: SiO2% by weight, A: Al2O3% by weight)

Additionally, blast furnace slag fine powder reacts with an alkali activator to produce a geopolymer with excellent mechanical/physical properties. Geopolymer generates N-A-S-H through the following hydration reaction, and this N-A-S-H is superior to C-S-H gel in terms of durability.

SiO ₂ , Al ₂ O ₃ + alkali metal ion → condensation reaction → Alumino-silicate gel (NASH)

Alkaline-activated geopolymer using blast furnace slag has a very fast initial reaction rate, which can cause shrinkage and cracking as well as a decrease in strength, so the polymer is mixed with blast furnace slag at a predetermined weight ratio and used as a binder. .

Calcium aluminate cement (CAC) mixed with blast furnace slag powder not only has superior compressive and adhesion strength compared to ordinary Portland cement (OPC), but also has superior chlorine ion penetration resistance. However, when calcium aluminate cement (CAC) is exposed to high temperatures and humidity, there is a detrimental conversion of metastable hexagonal aluminate hydrate to stable cubic calcium aluminate hydrate. Stable cubic calcium aluminate hydrate has a higher density than metastable hexagonal aluminate hydrate, so internal shrinkage occurs, and this internal shrinkage can cause porous microstructure and weakening of strength. These harmful conversions can make calcium aluminate cement (CAC) susceptible to chloride attack and other durability problems such as carbonation.

The harmful conversion of calcium aluminate cement (CAC) can be inhibited by magnesium oxide (MgO) reinforcing fibers. Magnesium oxide (MgO) reinforcing fibers not only significantly increase the compressive strength of the repair composition, but also inhibit the conversion of calcium aluminate cement (CAC) into stable hydrates and react with metastable hydrates to produce hydrotalcite. It was confirmed that the mixing ratio of magnesium oxide (MgO) reinforcing fiber to suppress harmful conversion of calcium aluminate cement (CAC) and generate hydrotalcite is 5 to 10 parts by weight per 100 parts by weight of binder.

Polymers include ethylene vinyl acetate (EVA), NR (Natural Rubber), NBR (Natural Rubber-Butadiene Rubber), SBR (Styrene-Butadiene Rubber), and polyvinyl acetate. Any one selected or a mixture of two or more may be used. The polymer is preferably mixed in an amount of 0.5 to 1.5% by weight of the total weight of the binder.

Magnesium oxide (MgO) reinforcing fibers (10) are magnesium oxide (MgO) nanostructures (11) in the form of numerous protrusions or fibers on the surface of magnesium metal in the form of fibers having a predetermined length, as shown in FIGS. 3 and 4. ), which produces hydrotalcite with a Mg-Al bonded structure through reaction with aluminum oxide (Al ₂ O ₃ ) and calcium aluminate cement (CAC).

Magnesium oxide (MgO) reinforcement fiber 10 is made by immersing magnesium metal in the form of fibers with a length of 5 to 20 mm and a diameter of 0.2 to 1.0 mm in a solution of oxalic acid dissolved in methanol or ethanol for a certain period of time. After forming a nanostructure by the reaction of magnesium ions (Mg ²⁺ ) and C ₂ O ₄ ^2- ions on the surface, magnesium oxide (MgO) in the form of protrusions or fibers is formed on the surface through heat treatment at 300-500°C. ) A nanostructure was formed.

More specifically, when magnesium metal in the form of fiber is immersed in a solution of 1M oxalic acid dissolved in methanol or ethanol solvent, stirred, and maintained at a temperature of approximately 25 to 30°C for 1 to 4 hours. As a result of the hydrogen ions in the solution reacting violently on the surface of magnesium, magnesium is oxidized to Mg ²⁺ ions and simultaneously reduced to hydrogen gas. The continuously eluted Mg2+ ions combine with C ₂ O ₄ ^2- ions in the solution and precipitate on the surface, forming a magnesium oxalate nanostructure.

When the magnesium metal in the form of a fiber with magnesium oxalate nanostructures formed on its surface is heat-treated at a temperature range of 300 to 500°C, the magnesium oxide (MgO) nanostructures (11) are formed on the magnesium oxide (MgO) reinforcing fibers (10). is completed.

The magnesium oxide (MgO) reinforcing fiber 10 produces more hydrotalcite than powder-like magnesium oxide (MgO) due to the numerous protrusive or fiber-shaped magnesium oxide (MgO) nanostructures 11 formed on its surface. There is an advantage to being able to proceed actively.

Hydrotalcite with a Mg-Al bonded structure created inside the repair material composition by mixing magnesium oxide (MgO) reinforcing fibers (10) and aluminum oxide (Al ₂ O ₃ ) prevents the diffusion of chlorine ions inside the mortar due to the ion exchange effect. This can provide the effect of increasing safety by preventing corrosion of reinforcing bars in concrete structures.

In order to further increase the reactivity of the magnesium oxide (MgO) reinforcing fibers, it is more preferable to pre-treat the magnesium oxide (MgO) reinforcing fibers by firing them at a temperature of 700 to 1000°C before mixing them with the binder. The magnesium oxide (MgO) reinforcing fibers fired at a temperature of 700 to 1000°C are more reactive than the unfired magnesium oxide (MgO) reinforcing fibers and the magnesium oxide (MgO) reinforcing fibers fired at a high temperature exceeding 1000°C. It was confirmed that it causes the hydrotalcite production reaction more actively and is effective in reducing shrinkage.

Aluminum oxide (Al ₂ O ₃ ) powder with a purity of 95% or more is suitable.

The alkaline activator is mixed with the binder to create a repair material. The alkaline activator can be a three-component alkaline activator consisting of sodium hydroxide, water glass, and water, and can be mixed at 40 to 60 parts by weight for 100 parts by weight of the binder. .

The thickener may be one or more of ethylcellulose-based, methylcellulose-based, and acrylic-based, and may be used in an amount of 0.3 to 1.0 parts by weight based on 100 parts by weight of the binder.

Zirconium silicate (ZrSiO ₄ ) powder can be used as the filler. Zirconium silicate (ZrSiO ₄ ) has a low thermal expansion coefficient, and the elastic modulus and refractive tension in the sintered body are the best among silicate ceramics. Filler containing zirconium silicate (ZrSiO ₄ ) powder is mixed with binder and alkali activator to ensure that the repair material has high compressive strength in a room temperature environment, and when applied to injection and filling methods for crack repair or cross-section restoration of concrete, It increases the time and improves injectability and filling properties.

A method of performing surface repair and cross-section restoration of a concrete structure using the above-described repair material composition for concrete surface repair and cross-section restoration will be described with reference to FIGS. 1 and 2 as follows.

First, a first step (S110, S210) of removing impurities, laitance, or deteriorated areas from damaged areas of the concrete structure; The second step of applying primer to the concrete structure (S120, S220); A third step (S130, S230) of applying the repair material composition to the concrete structure to which the primer has been applied or repairing the damaged area in case of cross-sectional damage; And it proceeds sequentially in the construction order of the fourth step (S140, S240), which involves applying a repair material composition or applying a durability-improving surface coating agent to the surface of the damaged area in the event of cross-sectional damage.

When surface repair is performed because efflorescence or heaving occurs on the surface of a concrete structure, as shown in FIG. 1, in the first step (S110), efflorescence or heaving, etc. on the surface is removed by grinding (S111), and high-pressure water is used to remove the surface. After washing and drying (S112), a penetrating alkali reducing agent can be applied to the carbonated concrete to restore the alkalinity of the concrete (S113).

When performing surface repair of a concrete structure, the step (S130) of applying the repair material composition to the concrete structure or repairing the damaged area in case of cross-sectional damage may be omitted.

In the case where cross-sectional restoration is performed due to severe deterioration of the concrete structure, such as delamination, spalling, salt damage, or neutralization of the concrete structure, as shown in FIG. 2, in the first step (S210), the deteriorated area is removed by chipping (S211). ), foreign substances are removed through high-pressure water washing and dried (S213), and then a penetrating alkaline reducing agent is applied to the carbonated concrete to restore the alkalinity of the concrete (S215).

If there is exposed reinforcing steel in the deteriorated concrete structure, additional work is performed to remove rust from the reinforcing bars (S212) and apply a rust preventive to the reinforcing bars (S214).

The permeable alkaline reducing agent is hydrolyzed by adding 10 to 50% by weight of distilled water as a diluent to 10 to 50% by weight of a water-soluble silicate inorganic compound as a binder and stirring at 150 to 200 rpm for 60 minutes while maintaining the temperature at 30°C; Dropping 20 to 50% by weight of a lithium compound into the mixture hydrolyzed in the previous step, maintaining the temperature at 30°C, and stirring at 150 to 200 rpm for 30 minutes; Adding 10 to 50% by weight of sol-state metal oxide dropwise to the mixture of the lithium compound in the previous step, maintaining the temperature at 50°C, and stirring at 150 to 200 rpm for 60 minutes; Maintaining the temperature of the mixture of metal oxides in the previous step at 50°C and stirring at 150 to 200 rpm, slowly adding 5 to 20% by weight of a silane coupling agent dropwise over 30 minutes and stirring for 2 hours; It can be completed by adding 0.1 to 5% by weight of a wetting agent to the mixture of the silane coupling agent in the previous step and stirring for 10 minutes.

This penetrating alkali reducing agent penetrates into neutralized concrete to maximize alkali recovery and improve the surface strength of concrete.

The primer used in the second step contains 10 to 50% by weight of a water-soluble silicate inorganic compound as a binder and 10 to 50% by weight of distilled water as a diluent, and prevents neutralization by penetrating and reacting on the surface of cement or concrete to form a strong bond. , 20 to 50% by weight of lithium compound to strengthen the surface, 10 to 50% by weight of metal oxide in sol state to improve the water resistance of the composition, shorten the curing time of the composition, and improve the chemical resistance of the concrete surface, penetration power. It may be comprised of 5 to 20% by weight of a silane coupling agent and 0.1 to 5% by weight of a wetting agent to enhance and induce good dispersion of the compound.

In the primer, the water-soluble silicate inorganic compound is one or more of sodium silicate with a specific gravity of 1.38 and a SiO2/Na2O molar ratio of 3.10 to 3.30, and potassium silicate with a specific gravity of 1.30 and a SiO2/K2O molar ratio of 3.3 to 3.6. The lithium compound is composed of lithium silicate with a specific gravity of 1.15 to 1.20 and a SiO2/Li2O molar ratio of 4.5 to 5.0, and one or more mixtures of lithium nitrite with a purity of 99% or more. The metal oxide is used. A water-dispersed silica sol, alumina sol, titanium oxide sol, or zirconia sol with a particle size of 10 to 20 nm is used, or a mixture of one or more of them is used, and the silane coupling agent is an organometallic alkoxy silane compound called MPTMS (3 -Methacryloxypropyltrimethoxysilane), GPTMS (3-Glycidoxypropyltrimethoxysilane), APTES (3-Aminopropyltriethoxysilane), Acryloxypropyltrimethoxysilane, Vinyltriethoxysilane, (Methacryloxymethyl)phenyldimethylsilane, or a mixture of more than one is used.

When using the repair material composition for surface repair purposes in the third step, the repair material composition can be applied as is to the concrete surface. However, when the repair material composition is used for cross-sectional restoration, the cross-sectional damage can be repaired by mixing a predetermined amount of water and fine aggregate into the repair material composition to make a repair material mortar.

The durability improvement surface coating used in the fourth step is 20 to 70% by weight of emulsion resin, 10 to 30% by weight of distilled water as a diluent, and organic metal alkoxy silane to improve crosslinking with inorganic fillers, permeability, chemical resistance, and wear resistance. 10-20% by weight of compound, 0.5-5% by weight of nitric acid (HNO3) as a catalyst, 0.5-5% by weight of ammonia (NH4OH, 28%) as a pH adjuster, 0.5-5% by weight of sodium polyphosphate as a dispersant, anatase as an inorganic filler Organic/inorganic consisting of 5 to 40% by weight of titanium dioxide powder, 1 to 5% by weight of iron oxide (Fe3O4) pigment as a coloring agent, 0.5 to 5% by weight of thickener, 0.1 to 5% by weight of wetting dispersant, and 0.5 to 5% by weight of antifoaming agent. Use a complex one-component surface coating agent.

In the one-component organic-inorganic composite surface coating used as such a durability improvement surface coating, the emulsion resin has a solid content of 40 to 50% by weight, a pH of 8 to 10, a viscosity of 1,000 to 3,000, and a glass transition temperature (Tg) of -10°C. It is anionic in nature, and the organometallic alkoxy silane compound is an organometallic alkoxy silane compound, which includes MPTMS (3-Methacryloxypropyltrimethoxysilane), GPTMS (3-Glycidoxypropyltrimethoxysilane), APTES (3-Aminopropyltriethoxysilane), Acryloxypropyltrimethoxysilane, Vinyltriethoxysilane, and (Methacryloxymethyl)phenyldimethylsilane. It is a mixture of one or more types, and the thickener is preferably one of ethylcellulose-based, methylcellulose-based, and acrylic-based.

The concrete durability improvement surface coating agent uses a network acrylic emulsion as a binder, which improves chemical resistance and abrasion resistance by modifying the linear acrylic emulsion into a three-dimensional network structure through re-crosslinking, and is an inorganic filler with submicron-sized particles. And by applying various admixtures, durability against external deterioration environments was further improved. And because it is manufactured in a one-component form, there is no need for a separate mixing process before use, and the construction period can be significantly shortened by dramatically shortening the drying time and complete curing time.

Here, the organic-inorganic composite one-component surface coating agent used as a durability improvement surface coating agent is made by adding 10 to 30% by weight of distilled water to 20 to 70% by weight of acrylic emulsion resin, maintaining the temperature at 30°C, and applying 10 to 10% at 200 to 250 rpm. Stirring for a minute; 10 to 20% by weight of a mixture of two or more organometallic alkoxy silanes was added dropwise over 1 hour to the mixture of distilled water in the previous step, maintained at 50°C, and stirred at 100 to 150 rpm for 1 hour to cause a condensation reaction. step; Adding 0.5 to 5% by weight of nitric acid dropwise to the mixture of two or more types of organometallic alkoxy silanes in the previous step, maintaining the temperature at 50°C, and stirring at 100 to 150 rpm for 2 hours to complete the condensation reaction; Adding 0.5 to 5% by weight of ammonia water dropwise to the mixture of nitric acid in the previous step, maintaining the temperature at 30°C, and stirring at 100 to 150 rpm for 2 hours to adjust the pH; Stabilizing by adding 0.5 to 5% by weight of sodium polyphosphate to the mixture of ammonia water in the previous step and stirring at 100 to 150 rpm until natural cooling to room temperature; In the previous step, add 5 to 40% by weight of titanium dioxide powder, 1 to 5% by weight of iron oxide (Fe3O4) pigment, 0.5 to 5% by weight of hydroxypropylmethylcellulose (HPMC), and 0.1 to 5% by weight of wet dispersant. %, and 0.5 to 5% by weight of antifoaming agent, using a homomixer at 2,000 rpm for 30 minutes.

In the repair material composition for concrete surface repair and cross-section restoration of the present invention, magnesium oxide (MgO) reinforcing fibers mixed with a binder and an alkali activator act to significantly increase compressive strength, and at the same time, magnesium oxide (MgO) reinforcement The reaction between fiber and aluminum oxide (Al ₂ O ₃ ) can promote the formation of hydrotalcite, which has a Mg-Al bonding structure, within the repair material. The ion exchange effect of hydrotalcite produced within the repair material can promote It can effectively inhibit chloride penetration.

In particular, magnesium oxide (MgO) reinforcing fibers are mixed at 5 to 10 parts by weight per 100 parts by weight of the binder to suppress the harmful conversion of calcium aluminate cement (CAC) into stable hydrates and react with metastable hydrates to form hydrotalcite. There is also the advantage of preventing weakening of the porous microstructure and strength due to internal shrinkage.

Example

blast furnace slag cement
(g) Polymer (g) Portland cement (g) Magnesium oxide reinforcing fiber (g) Aluminum oxide (g) Filler (g) Alkaline activator (g) Thickener (g)
Example 1 990 10 - 50 100 100 500 5 Example 2 990 10 - 100 100 100 500 5 Comparative Example 1 10 990 0 0 100 500 5

After mixing the repair material composition for surface repair and cross-sectional restoration in the mixing amount (g) as shown in Table 1, the repair material composition for surface repair and cross-sectional restoration was poured into a mold and cured at room temperature to prepare a specimen. The blast furnace slag cement used in Table 1 is 60% by weight of blast furnace slag fine powder, 5% by weight of lime, 10% by weight of anhydrous gypsum, 15% by weight of calcium sulfoaluminate (CSA), 1.0% by weight of water reducing agent, and calcium aluminate cement (CAC). It was mixed at a mixing ratio of 9% by weight. Additionally, ethylene vinyl acetate-based resin was used as the polymer, and magnesium oxide reinforcing fiber was pretreated by firing at 700°C. As shown in Figure 4, as a result of TD/DTG for Examples 1 and 2 and Comparative Example 1, the amount of hydrotalcite produced in Example 1 in which magnesium oxide and aluminum oxide were mixed together was compared to Comparative Example 1. However, in the case of Example 2, it was confirmed that the amount of hydrotalcite produced was significantly increased.

In addition, as shown in Table 2 below, the compressive strength and chlorine ion permeability test results showed that Examples 1 and 2 had increased compressive strength and significantly improved chlorine ion penetration resistance compared to Comparative Example 1.

division Compressive strength (MPa) Chlorine ion penetration resistance (Coulomb) Example 1 61.2 285 Example 2 63.3 198 Comparative Example 1 58.4 902

In the above, the present invention has been described in detail with reference to examples, but those skilled in the art will be able to make various substitutions, additions, and modifications without departing from the technical spirit described above. It is natural, and such modified embodiments should also be understood as falling within the scope of protection of the present invention as defined by the patent claims attached below.

10: Magnesium oxide (MgO) reinforcement fiber
11: Magnesium oxide (MgO) nanostructure

Claims (5)

A binder containing blast furnace slag cement and polymer including blast furnace slag fine powder, calcium sulfoaluminate (CSA), lime, anhydrous gypsum (CaSO ₄ ), and calcium aluminate cement (CAC); and,
For 100 parts by weight of the binder, 5 to 10 parts by weight of magnesium oxide (MgO) reinforcing fiber with a nanostructure formed on the surface, 5 to 10 parts by weight of aluminum oxide (Al ₂ O ₃ ) powder, 3 consisting of sodium hydroxide, water glass and water. 40 to 60 parts by weight of an alkali activator, 0.3 to 1.0 parts by weight of a thickener, and 10 to 20 parts by weight of a filler;
Including,
The magnesium oxide (MgO) reinforcing fiber is made by immersing magnesium metal in the form of fibers with a length of 5 to 20 mm and a diameter of 0.2 to 1.0 mm in a solution of oxalic acid dissolved in methanol or ethanol for a certain period of time, After forming a nanostructure by the reaction of magnesium ions (Mg ²⁺ ) and C ₂ O ₄ ^2- ions on the surface, a protrusion-shaped magnesium oxide (MgO) nanostructure is formed on the surface through heat treatment at 300~500℃. It is made up of formed fibers,
A repair material composition for concrete surface repair and cross-section restoration, wherein the magnesium oxide (MgO) reinforcing fiber is pretreated by firing at a temperature of 700 to 1000°C before being mixed with the binder. delete delete A first step of removing impurities, laitance or deteriorated areas from damaged areas of the concrete structure;
The second step of applying primer to the concrete structure;
A third step of applying the repair material composition according to paragraph 1 to the concrete structure in the primer-applied state or repairing the damaged area in case of cross-sectional damage; and,
A fourth step of applying the repair material composition or applying a durability improvement surface coating agent to the surface of the repaired area when the cross-section is damaged;
A repair method for a concrete structure including. According to claim 4, when surface repair is performed on the surface of a concrete structure, in the first step, efflorescence or loosening of the surface is removed by grinding, washed with high pressure water and dried, and then a penetrating alkali is applied to the carbonated concrete. The process of applying the reducing agent is performed sequentially,
When cross-sectional restoration is performed due to severe deterioration of the concrete structure due to delamination, spalling, salt damage, neutralization, etc. of the concrete structure, in the first step, the deteriorated area is removed by chipping and foreign substances are removed through high-pressure water washing. After drying, the process of applying a penetrating alkaline reducing agent to the carbonated concrete is sequentially performed.
A method of repairing a concrete structure in which, when performing the cross-section restoration, if there is exposed reinforcing steel in the deteriorated concrete structure area, the work of removing rusting the reinforcing steel and applying a rust preventive to the reinforcing steel is additionally performed.

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