KR102323879B1 - Method of repairing that provides electromagnetic shielding in concrete structures - Google Patents

Abstract

The present invention relates to a repair method for providing an electromagnetic wave shielding function in a concrete structure. As graphene-coated polyarylate fibers are used as repair materials, the repair method provides electromagnetic shielding performance while improving bending strength and water resistance, and improves the durability of the repair site. The repair method of the present invention includes a surface treatment step; a deteriorated part cleaning step; a surface reinforcement application step; a repair material application step; a surface protection material application step; and a ceramic coating material application step.

Description

Method of repairing that provides electromagnetic shielding in concrete structures

The present invention relates to a method for repairing a concrete structure, and more particularly, to a repair material that provides an electromagnetic wave shielding function and repairs deterioration in the cross section of a concrete structure that has been damaged by intrusion of chloride, neutralization of concrete, and chemical corrosion. It relates to a method of repairing a concrete structure using the composition.

Concrete generally consists of aggregates such as water, cement, sand, and gravel, and is used to form building structures using a hydration reaction in which cement and water react and harden.

Concrete durability is defined as the ability of concrete to resist weather, chemical erosion, abrasion, and other deterioration processes, which means that deterioration of concrete structures occurs due to various causes.

In general, the cause of deterioration of the concrete structure in the area where the repair material is applied can be divided into chemical deterioration and physical deterioration. The causes of physical deterioration include deterioration due to freezing and thawing, crack deterioration due to shrinkage and load, and the like, and can be divided into deterioration in special cases such as fire.

Due to the occurrence of such deterioration, when the damage is severe, the concrete falls off and the reinforcing bars in the concrete are exposed or corroded from the inside, resulting in deterioration of durability and load-bearing capacity, leading to problems such as shortening the service life of the structure. will do

Various technologies have been proposed as repair material compositions for repairing and reinforcing concrete structures. For example, in Korean Patent Registration No. 0975371, 16 to 19 wt% of ultra-fast cement, 4 to 5 wt% of straight steel fiber, 33 to 39 wt% of fine aggregate %, coarse aggregate 34-35% by weight, water 6-7.9% by weight, high-performance water reducer and retarder 0.5-0.6% by weight. A super-fast-hardening steel fiber-reinforced concrete composition and a pavement repair method using the same are described.

However, according to the above patent, there is a problem of cracking due to premature setting, which is inevitable due to the use of ultra-high speed cement, although emergency construction is possible by using ultra-velocity cement. As a result, post-cracking occurs due to repeated loads, etc.

Although various methods of repairing concrete structures have been developed so far, there is a continuous demand for the development of repair methods that express new functions, enhance performance, or make workability convenient.

An object of the present invention is to provide a method for repairing a concrete structure using a new repair material to which a specific function is added and components constituting the repair material are improved in order to satisfy the above requirements.

The present invention in order to solve the above problems, a surface treatment step of removing foreign substances and deteriorated parts of the concrete structure; Deteriorating part cleaning step of cleaning the foreign substances of the surface-treated concrete structure with high-pressure washing water; a surface reinforcement material application step of applying a surface reinforcement material to the concrete structure from which the foreign matter has been removed; On the surface reinforcing material application site, 30-40 wt% of cement, 30-50 wt% of silica sand, 5-10 wt% of expansion material, 5-20 wt% of admixture, 0.2-1.5 wt% of fluidizing agent, graphene-coated polyarylay A repair material application step of applying a repair material comprising 0.5 to 5% by weight of the fiber and 1 to 5% by weight of a polymer; a surface protection material application step of applying a surface protection material on the repair material application site; and a ceramic coat material application step of uniformly applying the ceramic coat material after the surface protection material is applied.

According to the present invention, the repair method using the repair material of the present invention uses graphene-coated polyarylate fiber as a repair material component, thus providing electromagnetic wave shielding performance and improving flexural strength and water resistance to improve the durability of the repair site. becomes

The repair method of the concrete structure of the present invention includes a surface treatment step of removing foreign substances or deteriorated parts from a part to be repaired of the concrete structure and treating the surface, and a deterioration part of washing the foreign substances of the surface-treated concrete structure with high-pressure washing water A cleaning step, a step of applying a surface reinforcement material to the concrete structure from which the foreign matter has been removed, a step of applying a concrete repair material on the surface reinforcement material applied thereon, applying a surface protection material on the repair material application site, and the surface It is made including the step of applying a ceramic coating material after application of the protective material.

In the surface treatment step, the cladding material is removed from the cross section of the concrete structure caused by aging phenomena such as salt damage, neutralization (carbonation) and chemical corrosion, or the exposed coarse aggregate is filled and compensated, water contamination is removed, or rust is contaminated. It deals with all the different types of phenomena, such as removing parts, removing floats and corrosion. As the most important pre-treatment step, first, the deteriorated concrete cross section is completely removed using a tool such as a grinder to level the surface and process it densely and densely.

The cleaning step is a process of washing foreign substances present on the cross-section of the surface-treated concrete structure with high-pressure washing water. get out and remove

The surface reinforcing material application step is a process of applying the surface reinforcing material to the concrete structure from which the foreign matter has been completely removed.

Using a roller, paint brush, or air spray gun, impregnate the surface reinforcing material at a level of 0.32 kgf/cm2 as it is and apply it evenly. As the surface reinforcing material, a commercially available surface reinforcing material may be used, and a permeable surfactant, reactive silica, or silica-based water repellent may be selected and used alone or in combination of two or more.

In the step of applying the repair material, cement 30-40% by weight, silica sand 30-50% by weight, expansion material 5-10% by weight, admixture 5-20% by weight, fluidizing agent 0.2-1.5% by weight, polyarylene coated with graphene A repair material comprising 0.5 to 5% by weight of the fiber and 1 to 5% by weight of the polymer is applied.

The repair material is applied to a thickness of about 1 to 1.5 cm at a time using hand-made plastering or rollers, and of course, it can be repeatedly applied several times depending on the damage thickness. For example, the cross-sectional thickness of the concrete structure to be repaired is 3 cm, and the cross-section restoration material is applied twice at an amount of 66.2 kg/m2.

As another embodiment, when applying the repair material on the cross section to be repaired of the concrete structure, it is important to secure the thickness so that the construction thickness is about 2 mm or more than the surface. The reason for securing the construction thickness to about 2 mm or more is because it is the minimum thickness required to deal with irregularities and defects on the outermost base surface of the concrete structure.

In the step of applying the surface protection material, the surface protection material is applied.

As the surface protection material, a commercially available surface protection material may be used, but a mixture of cement or slug, silica sand, an acrylic polymer (Acryl base polymer), and a surfactant may be used. The surface protection material is applied by hand plastering, and applied to a thickness of about 1.5 mm (2.2 kg/m2) when applied once.

In the step of applying the ceramic coating material, using a roller, a paint brush, an air spray gun, etc., the ceramic coating material is uniformly applied to the surface protection material as it is, 0.1 to 0.3 mm (0.44 to 0.46 kg/m 2 ) as it is. Apply.

As another embodiment of the present invention, a mixture of an acrylic polymer or a porous material may be used together with a ceramic-based material to be used as a surface coating material in the final finishing process.

A building or bridge constructed by the repair method of a concrete structure using the repair material composition for a concrete structure of the present invention has excellent adhesion, air permeability, hardness, etc. It can have antibacterial function to prevent growth activity of bacteria, etc. In addition, construction time is reduced due to convenient workability, and electromagnetic wave shielding is improved, so it is possible to protect against EMP exposure.

The composition component of the concrete repair material of the present invention is 30-40 wt% of cement, 30-50 wt% of silica sand, 5-10 wt% of expansion material, 5-20 wt% of admixture, 0.2-1.5 wt% of fluidizing agent, and graphene is coated 0.5 to 5% by weight of polyarylate fibers and 1 to 5% by weight of polymer.

The cement component is a main component used to secure various mechanical strengths such as compressive strength and flexural strength of the hardened body, and the cement reacts with water to produce calcium silicate hydrate and calcium aluminate hydrate, which are main hydration products. At this time, mechanical strength is exhibited, and it can be used as a material for construction and civil engineering for various purposes.

As the cement, one to five types of cement can be used depending on the purpose of the repair concrete. In particular, in order to increase the resistance to sulfate or calcium chloride used for resolving road freezing, a sulfate-resistant cement, a type 5 Portland cement, or It is effective to use slag cement or the like. In addition, crude steel cement or alumina cement may be used to quickly secure early strength.

The content of cement is composed of 30 to 40 wt% relative to the total weight of the cross-section repair material composition. When it is 30 wt% or less, the adhesion is reduced, and when it is 40 wt% or more, the surface strength is increased in the mortar mixed with silica sand (sand). Since the viscosity of the material increases and the on-site workability decreases, an appropriate content ratio is selected according to the characteristics of the concrete structure itself or the external environment to be repaired.

As the silica sand component, 30 to 50 wt% of the silica sand adjusted to an appropriate particle size is used based on the total weight of the cross-section repair material composition. The weight ratio of general cement or slag cement and silica sand is not particularly limited, but may be used in a mixing ratio of 1:1 or 1:3 so that a mortar whose mixing ratio is adjusted to match the characteristics of the cross section of the concrete structure to be repaired can be used.

The particle size of the silica sand is not particularly limited, but a particle size uniformly adjusted to a predetermined particle size within the range of 0.05 mm to 2 mm is used. This is in order not to affect the dispersibility of the section repair material according to the characteristics and purpose of the concrete structure to be restored and the air permeability in the porosity of the concrete after repair work.

The expansion material component may be used in an amount of 5 to 10 wt % based on the total weight of the cross-section repair material composition. If it is less than 5 wt %, there is no effect in reducing cracks due to shrinkage of cement, and if it is 10% or more, swelling due to expansion or expansion cracks etc. will occur.

The expansion material is calcium sulfo-aluminate, calcium oxide (Ca0), calcium sulfate (CaSO4), alumina cement, calcium aluminate hydrate and Portland cement containing calcium sulfoaluminate. (portland cement) can be used by mixing at least one or more.

Inorganic expansion materials can prevent shrinkage and cracking of cement by making the structure of the hardening body dense and minimizing drying shrinkage by exerting the expansion force of the expansion material.

As a preferred embodiment of the present invention, the inorganic expansion material included in the cross-section restoration material may use a CSA-based mineral, that is, calcium sulfo-aluminate as a main component, and when it reacts with water, the expandable material etringite ( ettringite), which reduces the drying shrinkage of the hardened cement and reduces the occurrence of cracks.

The admixture component is used to improve long-term durability, and pozzolan and/or fly ash may be used. Pozzolan, fly ash or slag powder imparts watertightness to the concrete structure and improves resistance to volume change due to wetting and freezing and thawing.

The admixture component may be used in an amount of 5 to 20 wt% based on the total weight of the cross-section repair material composition, and when 20 wt% or more is used, a decrease in initial compressive strength may occur.

The fluidizing agent component is added to provide workability in the repair method of concrete structures, and one or two or more of melamine-based, naphthalene-based, and carboxyl-based fluidizing agents are used in combination.

The fluidizing agent can be used in an amount of 0.2 to 1.5 wt % based on the total weight of the cross-section repair material composition, but when it is less than 0.2 wt %, there is no fluidity enhancing effect, and when used in excess of 1.5 wt %, there is no great effect on improving the fluidity, and When a large amount is used as an expensive material, the economic feasibility is greatly reduced.

The graphene-coated polyarylate fiber, as a reinforcing material, improves strength such as flexural strength and tensile strength in the concrete cross-section repair method, and improves resistance to drying shrinkage to suppress cracks during curing and improve initial dispersibility. improve

In addition, it is possible to strengthen eco-friendly and semi-permanent durability, prevent corrosion of concrete, and provide fire resistance and waterproof function, so that damage caused by salt damage, chemical corrosion, mold or bacteria bacteria, pathogenic microorganisms, etc. can be maintained to be minimized.

Graphene is a carbon-based nanomaterial with graphite peeled off further, and has a large surface area compared to other nanomaterials, has excellent mechanical strength, thermal and electrical properties, and has antibacterial properties.

Graphene-coated polyarylate fiber is a two-dimensional plate-shaped graphene, which maximizes the horizontal area, so it can perform excellently in the function of preventing moisture barrier properties and moisture movement. Since the tensile strength is increased, strength and workability can be improved when constructing a section repair work of a concrete structure using the section repair material composition.

In addition, due to the excellent thermal and electrical conductivity of graphene, a conductive network is formed in the repair layer formed by the repair, thereby increasing the conductivity, thereby improving external electromagnetic wave shielding properties. In addition, it is possible to control temperature cracking by rapidly transferring heat generated during cement hydration process.

Preferably, the content of graphene in the graphene-coated polyarylate fiber is 6 to 30% by weight. If it is less than 6% by weight, the electromagnetic wave shielding performance and water resistance decrease, and if it exceeds 30% by weight, it is economically undesirable. not.

The graphene-coated polyarylate fiber may be used in an amount of 0.5 to 5 wt% based on the total weight of the cross-section repair material composition. If it is less than 0.5 wt%, the improvement in mechanical strength and electromagnetic wave shielding properties is insignificant, and if it exceeds 5 wt%, agglomeration occurs. As a result, fluidity and performance may deteriorate.

As an example of the polyarylate fiber, Japan Kuraray's Vectran ^® fiber may be mentioned.

Vectran fiber is a copolymer of p-hydroxybenzoic acid in the benzene ring component and 6-hydroxy-2-naphthoic acid in the naphthalene ring component.

Vectran fiber is a high-strength, high modulus fiber, and has excellent mechanical properties compared to aramid fiber and carbon fiber, and has excellent tenacity, moisture resistance, environmental resistance, hydrolysis resistance, and vibration resistance.

For this reason, when Vectran fiber is used in the present invention, mechanical strength such as flexural strength and tensile strength can be improved, and cracks on the surface can be reduced during curing, so that the initial construction stability is excellent.

When Vectran fibers are processed by methods such as coating and water dispersion mixing, moisture absorbed by the fibers may remain in the fibers. Even after a long period of time, deterioration of physical properties does not occur.

Even when graphene is coated by these properties, the physical properties of the Vectran fiber do not deteriorate during the coating process, but rather the properties of graphene are added to improve the physical properties as a reinforcing material.

The graphene-coated polyarylate fiber of the present invention may be prepared by the following method.

Polyarylate fibers exhibit hydrophobicity due to the above-described properties, so that coating is not easy.

In the present invention, in order to solve this problem, reduced graphene oxide prepared by etching the surface of Vectran fiber, treating it with polyethyleneimine, treating graphene oxide with an aqueous dispersion solution to coat graphene oxide, and reducing graphene oxide Vectran fibers coated with pins can be used.

The etching is performed with a strong alkaline solution such as lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), rubidium hydroxide (RbOH), cesium hydroxide (CsOH), calcium hydroxide (Ca(OH) _{2 )} However, a KOH or NaOH solution is more preferable.

The treatment with the strong alkali solution can be processed under the conditions of 55 to 65 ℃ at a concentration of 30 to 45% by weight.

If it is less than the above condition, the surface of the Vectran fiber is not sufficiently wet to be able to accept polyethyleneimine, and if it is exceeded, the mechanical strength of the fiber is lowered, which is not preferable.

Polyethyleneimine solution is added to the suspension of Vectran fiber by the etching and mixed to obtain Vectran fiber having a cationized surface.

Polyethylenimine is a polymer having an amino group and exhibits cationic properties in a solvent.

Etched Vectran fibers are weakly negatively charged in water. When a cationic polymer is added here, electrostatic adsorption is made between negative and positive charges, so that polyethyleneimine is applied to the surface of Vectran fiber, and the surface is cationized because polyethyleneimine has a large number of positive charges. Due to this, the coating of graphene oxide may be facilitated.

Although graphene has excellent physical properties, it is easy to agglomerate and the specific surface area is greatly reduced, so it is not easy to process it into a coating or the like.

In the present invention, by using graphene oxide to coat graphene on Vectran fibers, coating is easy by functional groups and excellent adhesion is obtained. Then, graphene is made by reduced graphene oxide obtained by reducing graphene oxide. This is to enable the expression of unique characteristics.

Although graphene oxide contains a hydroxyl group, an epoxide group, a carboxyl group, a lactol group, etc., it has excellent adhesion to an adherend due to these functional groups, and also has excellent bending resistance due to its two-dimensional plate-like flexible structure. It has good elasticity and can be well attached to the surface of the adherend, does not deteriorate the properties of the adherend, and is advantageous in terms of price as a material in the previous stage for making graphene.

In addition, due to the flexible two-dimensional plate-like cross-sectional structure, the specific surface area is wide and the network by continuous contact of graphene can be formed, thereby improving electromagnetic wave shielding and rupture strength.

A solution in which graphene oxide is dispersed can be prepared by putting graphene oxide in an aqueous solvent or an organic solvent and performing high-speed stirring or ultrasonic treatment.

A Vectran fiber coated with graphene oxide can be obtained by adding a solution in which the graphene oxide is dispersed to the polyethylenimine-treated Vectran fiber suspension and mixing with stirring.

Thereafter, a reducing agent is added to reduce a portion, and then the reduction is completed by irradiating microwaves, thereby separating the reduced graphene oxide-coated Vectran fiber from the suspension, and reducing graphene oxide, that is, graphene-coated Vectran. fibers can be produced.

In this case, the reducing agent is selected from hydrazine, an alkyl hydrazine derivative, and ascorbic acid.

The graphene oxide obtained through the oxidation reaction of graphite has various oxygen functional groups in the molecule, and the physicochemical properties are deteriorated. For this reason, it is known that heat or chemical methods should be used for reduction treatment.

Reduction using a reducing agent in solution can be reduced at a low temperature, but during the reduction process, aggregation occurs due to van der Waals force, so that the graphene-coated Vectran fibers of the present invention are aggregated and dispersed again for the final product. There is a problem that a conductive network cannot be formed by graphene.

In the present invention, after adding a reducing agent, the reaction is carried out at room temperature, but the aggregation is suppressed by setting the amount of the reducing agent to be the same in weight ratio compared to graphene oxide, and then the reduction is completed by adding a microwave to solve the above problem.

Meanwhile, a polymer compound having an acidic group in a side chain may be further added to the solution in which the graphene oxide is dispersed.

Due to this, dispersibility and transparency of graphene oxide in an aqueous solvent are further improved, and adhesion with an adherend is further improved, so that the graphene coating film can be maintained even in the final product.

It is preferable that the number of acidic groups contained in the repeating unit of the polymer compound having an acidic group is 1 to 5 and a weight average molecular weight of 10,000 to 10,000,000.

The polymer compound having an acidic group includes carboxymethyl cellulose, alginic acid, polystyrene sulfonic acid, and the like.

The polymer compound having an acidic group is preferably used in an amount of 0.5 to 2 times by weight relative to graphene oxide.

In the graphene-coated Vectran fiber of the present invention, graphene oxide having a flexible and two-dimensional plate-like cross-sectional structure is uniformly and strongly attached to the surface to form a conductive network film, and while this structure is maintained as it is, graphene oxide is reduced. It is changed to graphene so that the intrinsic properties of graphene can be sufficiently expressed.

Due to this, excellent conductivity by graphene is expressed, and electromagnetic wave shielding performance and water resistance can be improved.

The polymer component is added to increase adhesion without being significantly affected by the conditions of the concrete or concrete base surface. Acrylic, EVA, polyvinyl alcohol, methyl methacrylate, vinyl acetate, SBR. etc. may be used.

When the polymer is added in an amount of less than 1 wt%, there is no great effect on improving fluidity and adhesion. When added in excess of 5 wt%, the strength of the hardened body is greatly reduced, and the viscosity of the concrete is increased, so that the surface is clean. There is a problem that the finishing work is difficult.

On the other hand, acrylic polymers are widely used at low cost, but their water resistance is weak, the adhesion to existing concrete is reduced even with a little moisture, and the performance is deteriorated even after absorbing a small amount of water after drying, which can cause cracks or lifting after repair. .

In addition, as the size of the polymer particles increases, aggregation of the polymer occurs due to the formation of large particles, which causes a decrease in adhesion and water resistance.

To solve this problem, a modified acrylic emulsion can be used as a polymer component.

The modified acrylic emulsion is an aqueous solution containing an anionic surfactant (C) a component consisting of a monomer (A) mainly containing an alkyl ester of (meth)acrylic acid having 4 to 8 carbon atoms in the alkyl group and an adhesion strengthening resin (B). By emulsifying and dispersing, a monomer emulsion (D) having an average particle diameter of 0.4 µm or less is prepared, and this is added dropwise to an aqueous polymerization solution (F) containing a water-soluble polymerization initiator and anionic surfactant (E) and polymerized to form polymer particles. It was prepared with an average particle size of 0.05 to 0.15 μm.

According to this production method, the oil oil formed by dissolving the adhesion-reinforcing resin (B) in the monomer (A) is mechanically forcibly emulsified and dispersed in the anionic surfactant (C) to prepare a monomer emulsion having a small particle size, which is then water-soluble Polymerization is carried out while dripping in an aqueous solution (F) for polymerization containing a polymerization initiator and anionic surfactant (E). A polymer having a small particle size can be obtained according to the dissolution and outflow of the monomer in the aqueous solution for polymerization (F).

In addition, in the modified acrylic emulsion prepared in this way, the polymer component is finely dispersed.

The modified acrylic emulsion prepared in this way improves the adhesion with concrete because the size of the polymer particles is small, and the water resistance, heat resistance and weather resistance are improved, and the performance of the concrete repair material can be improved because separation of the material does not occur.

The alkyl group (meth)acrylic acid alkyl ester having 4 to 8 carbon atoms in the alkyl group used in the modified acrylic emulsion of the present invention requires dissolving the adhesion strengthening resin in the monomer mixture, so that the alkyl group must have 4 or more carbon atoms. When carbon number of an alkyl group is 3 or less, it becomes difficult to melt|dissolve adhesion strengthening resin in the mixture of a monomer. In addition, when the carbon number of the alkyl group is 9 or more, the solubility in water decreases, and the unsaturated monomer in the monomer oil droplets does not migrate to the surfactant micelles, so it is difficult to reduce the average particle diameter of the aqueous emulsion of the synthetic resin.

Alkyl (meth)acrylate having 4 to 8 carbon atoms in the alkyl group used in the modified acrylic emulsion of the present invention is butyl, iso-butyl, t-butyl, pentyl, cyclohexyl, heptyl, octyl, and 2-ethylhexyl of acrylic acid or methacrylic acid. and alkyl esters, such as 2 ethylhexyl acrylate and n-butyl acrylate are more preferable. Content in monomer whole quantity is 50 weight% or more, in order to improve adhesive force and the solubility of adhesion-reinforced resin, Preferably it is 70 weight% or more.

The monomer having a carboxyl group used in the modified acrylic emulsion of the present invention is used to impart mechanical stability to the aqueous emulsion of the synthetic resin. In order to impart mechanical stability to the aqueous emulsion of synthetic resin by copolymerizing a monomer having a carboxyl group, it is preferable to neutralize the aqueous emulsion of synthetic resin with ammonia water, etc. to adjust the pH to 7 or higher. As a result, it is possible to reduce the amount of surfactants that reduce water resistance.

Examples of the monomer having a carboxyl group used in the modified acrylic emulsion of the present invention include methacrylic acid, acrylic acid, maleic acid, and itaconic acid. The content in the total amount of the unsaturated monomer is 0.5% by weight or more, preferably 1.0% by weight or more to improve the mechanical stability of the aqueous emulsion of the synthetic resin, and 5% by weight or less, preferably 3% by weight or less to improve water resistance.

In the present invention, various monomers copolymerizable with an unsaturated monomer having an alkyl (meth)acrylate having an alkyl group having 4 to 8 carbon atoms and a carboxyl group can also be used as long as the dissolution of the adhesion strengthening resin in the monomer mixture is not reduced. Examples thereof include esters of (meth)acrylic acid such as methyl, ethyl, propyl, benzyl, disyl, isodisyl, dodecyl, isododecyl, lauryl, tridecyl, isotridecyl, and tetradisyl. The content in the total amount of the monomer is preferably 49.5% by weight or less.

The monomer having an alkoxysilyl group used in the modified acrylic emulsion of the present invention can improve water resistance by suppressing the swelling of the dry film. Examples of the unsaturated monomer having an alkoxysilyl group used in the present invention include vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyldimethoxysilane, γ-acryloxypropyl trimethoxysilane, γ-acryloxypropyldimethoxysilane, and the like. The amount used is preferably 0.01 to 1.0% by weight, preferably 0.05 to 0.5% by weight. When the amount used is less than 0.01% by weight, the effect of improving water resistance becomes small, and when it exceeds 1.0% by weight, on the contrary, the film formability of the dry film decreases and the water resistance decreases.

Examples of the adhesion strengthening resin (B) used in the modified acrylic emulsion of the present invention include aliphatic petroleum resins, alicyclic petroleum resins, and hydrogenated rosin resins. In particular, adhesion-reinforced resins with a softening point of 80° C. or higher that do not easily diffuse into an aqueous phase, and adhesion-reinforced resins with an acid value and a hydroxyl value of 0.1 or less that do not easily diffuse into an aqueous phase are preferred. Among them, alicyclic petroleum resins are preferable. The amount of the adhesive-reinforced resin resin used is preferably 4 to 20 parts by weight in order to improve the adhesive force with respect to 100 parts by weight of all monomers.

The anionic surfactant (C) used in the modified acrylic emulsion of the present invention is used as an emulsifier, and an anionic surfactant having a polyoxyalkylene structure and an unsaturated double bond is preferable.

The stability of the monomer emulsion is improved by the polyoxyalkylene structure, and the mechanical stability of the polymer emulsion is improved by the unsaturated double bond.

Commercialized products include Aquaron KH-10 and KH-5 (Jeil Industrial Pharmaceutical Co., Ltd., Japan).

The amount to be used is 0.5 to 2.0 parts by weight based on 100 parts by weight of the unsaturated monomer mixture in the monomer emulsion (C) in which the monomer oil droplets having an average particle size of 0.4 μm or less are formed by emulsification and dispersion. Moreover, 0.1-2.0 weight part is used in (F) in surfactant aqueous solution.

As the water-soluble polymerization initiator used in the modified acrylic emulsion of the present invention, sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, tert-butyl hydroperoxide and the like may be used.

Since the modified acrylic emulsion of the present invention has a small particle size, it has excellent permeability and miscibility into the components of the repair material composition, improves the workability of the repair material, imparts a viscosity suitable for construction, and completely hydrates the cement-based compound. It is possible to three-dimensionally connect the pores of the hydration curing agent that are not formed to form a dense tissue and improve durability.

The composition of the concrete cross-section repair material of the present invention can suppress corrosion of reinforcing bars in concrete structures due to neutralization and extend the lifespan of concrete structures.

In addition, it is possible to improve adhesion to the deterioration repair site of concrete and provide electromagnetic wave shielding and antibacterial properties by graphene.

In addition, the adhesion and wettability to the repair section are improved, so that both roller and plastering work are possible, thereby improving work convenience.

Hereinafter, the concrete repair material of the present invention will be described in detail through the following preparation examples and examples.

[Production Example 1]

As a polyarylate fiber, Vectran (trade name) fiber (length 12 mm, diameter 0.022 mm, tensile strength 3,200 MPa, modulus of elasticity 75 GPA, elongation at break 3.8%) was treated at 60 ° C. for 5 minutes in NaOH solution of 30 wt % concentration. Vectran fibers with an etched surface were obtained.

After putting the Vectran fiber in a polyethyleneimine aqueous solution and stirring to uniformly mix it, an aqueous dispersion of graphene oxide prepared by the Hummer method is added and stirred to uniformly mix, so that 30 wt% of graphene oxide is coated A suspension of Vectran fibers was prepared.

The same amount of graphene oxide and hydrazine were added to the suspension of the Vectran fiber coated with graphene oxide, mixed, and reacted for 3 days to partially reduce.

Thereafter, the Vectran fiber was put into a microwave oven, and the microwave oven (2.45GHz) was operated at full power (1000W) for 30 seconds and then released for 20 seconds, which was repeated twice. The dispersion of the suspension gradually turned black to complete the chemical reduction of graphene oxide. The resulting dispersion was centrifuged for 15 minutes (5000 rotations per minute (rpm)) to finally produce reduced graphene oxide-coated Vectran fibers. Then, the Vectran fiber was dried in a vacuum atmosphere for 1 day to prepare a graphene-coated Vectran fiber.

[Production Example 2]

Graphene-coated Vectran fibers were prepared in the same manner as in Preparation Example 1, except that carboxymethylcellulose (Mw=300,000) was further added to the aqueous dispersion of graphene oxide in Preparation Example 1.

[Production Example 3]

80 g of 2-ethylhexyl acrylate, 17.44 g of methyl methacrylate, 2.4 g of acrylic acid, 0.16 g of γ-methacryloxypropyltrimethoxysilane, 10 g of Arcon M-135 (Arakawa Chemical Industries, Ltd., Japan, alicyclic petroleum resin) and stirred at room temperature until the mixture became uniform. Add 1.2 g of Aqualon KH-10 (Dai-Ichi Kogyo Seiyaku co., Ltd., Japan, anionic reactive surfactant) and 92 g of water to this, emulsify and disperse at a pressure of 400 kg/cm 2 with a high-pressure homogenizer, and average A monomer emulsion having a particle diameter of 0.25 µm was obtained.

An aqueous surfactant solution consisting of 0.8 g of Aqualon KH-10 (Dai-Ichi Kogyo Seiyaku co., Ltd., Japan, anionic reactive surfactant) and 34 g of water was added, and the temperature was raised to 80° C. while stirring. Here, 3% of the above-mentioned monomer emulsion and 0.06 g of potassium persulfate were added to initiate emulsion polymerization. After that, 97% of the monomer emulsion, 0.2 g of potassium persulfate, and 8 g of water were slowly added over 3 hours, aged at 80° C. for 2 hours, cooled to room temperature, and adjusted to pH 8.5 with 25% aqueous ammonia solution 180 A modified acrylic copolymer emulsion was prepared by filtration through a mesh wire mesh. The average particle diameter of the prepared modified acrylic copolymer emulsion was 0.11 μm, and the solid content was 45.1%.

[Example 1]

Cement 35% by weight, silica sand 46% by weight, CSA-based expansion material 7% by weight, pozzolan 7% by weight, naphthalene-based fluidizing agent 1% by weight, graphene-coated Vectran fiber of Preparation Example 1 1.5% by weight and acrylic resin 2.5 A concrete repair material was prepared using the composition consisting of weight %.

[Example 2]

A concrete repair material was prepared in the same manner as in Example 1, except that in Example 1, the graphene-coated Vectran fiber was used as in Preparation Example 2.

[Example 3]

A concrete repair material was prepared in the same manner as in Example 1, except that the modified acrylic copolymer of Preparation Example 3 was used instead of the acrylic resin in Example 1.

[Comparative Example 1]

A concrete repair material was prepared in the same manner as in Example 1, except that PP short fibers (length 12 mm, diameter 0.2 mm) were used instead of graphene-coated Vectran fibers in Example 1.

[Comparative Example 2]

Except for using 1.2 wt% of short polypropylene fibers (length 12 mm, diameter 0.2 mm) instead of Vectran fibers coated with graphene in Example 1, and making it 0.3 wt% of graphene powder in the composition A concrete repair material was prepared using the same method as in Example 1.

For the concrete repair materials of the Examples and Comparative Examples, the specimens were prepared by pouring 24 hours after pouring into the mold, and performing wet curing (temperature 20±3℃, RH 80±10%) until 7 and 28 days of age, Physical properties were evaluated according to KS F 4042.

The electromagnetic wave shielding rate was evaluated at 1 GHz according to the ASTM D 0304 test standard using a sample molded into a plate having an average thickness of 1 mm.

The evaluation results are shown in Table 1 below.

Age (days) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Compressive strength (Kgf/㎠) 7 days 411 409 412 392 384 28 days 493 486 499 463 451 Adhesive strength (Kgf/㎠) 7 days 20 21 22 20 19 28 days 26 26 27 25 24 Flexural strength (Kgf/㎠) 7 days 69 70 68 63 61 28 days 96 97 94 85 83 Length change rate (%) - 0.012 0.012 0.012 0.016 0.016 Water absorption coefficient (Kg/㎡·h ^0.5 ) - 0.09 0.10 0.08 0.76 0.68 anti-fungal test
(microorganism reduction rate %) 82 81 85 60 75 Electromagnetic wave shielding rate (dB) - 52 55 51 9 23

From the results of Table 1, it can be seen that the concrete repair material of the present invention has excellent electromagnetic wave shielding rate and excellent mechanical properties and water resistance.

It can be confirmed that the remarkably improved electromagnetic wave shielding property is due to the fact that graphene is uniformly dispersed by the fibers in the composition and a conductive network is formed by the network of the dispersed fibers.

Claims (5)

A surface treatment step of removing foreign substances and deteriorated parts of the concrete structure;
Deteriorating part cleaning step of cleaning the foreign substances of the surface-treated concrete structure with high-pressure washing water;
a surface reinforcement material application step of applying a surface reinforcement material to the concrete structure from which the foreign matter has been removed;
On the surface reinforcing material application site, 30-40 wt% of cement, 30-50 wt% of silica sand, 5-10 wt% of expansion material, 5-20 wt% of admixture, 0.2-1.5 wt% of fluidizing agent, graphene-coated polyarylay A repair material application step of applying a repair material comprising 0.5 to 5% by weight of the fiber and 1 to 5% by weight of a polymer;
a surface protection material application step of applying a surface protection material on the repair material application site; and
and a ceramic coat material application step of uniformly applying the ceramic coat material after the surface protection material is applied;
The graphene-coated polyarylate fiber,
After preparing an aqueous dispersion solution of graphene oxide in which graphene oxide and a polymer compound having an acidic group in the side chain are mixed and dispersed,
It is prepared by etching the surface of the polyarylate fiber, treating it with polyethyleneimine, treating the graphene oxide aqueous dispersion solution to coat the graphene oxide, and reducing the graphene oxide,
The high molecular compound having an acidic group in the side chain is selected from carboxymethyl cellulose or alginic acid and used in an amount of 0.5 to 2 times by weight relative to the graphene oxide, a repair method to provide an electromagnetic wave shielding function in a concrete structure . The method of claim 1,
A repair method for providing an electromagnetic wave shielding function in a concrete structure, characterized in that the graphene content is 6 to 30% by weight in the graphene-coated polyarylate fiber. delete The method of claim 1,
The reduction is a repair method for providing an electromagnetic wave shielding function in a concrete structure, characterized in that it is made by adding an equal amount of a reducing agent in a weight ratio to the graphene oxide, reacting at room temperature, and then applying a microwave. The method of claim 1,
Wherein the polymer is selected from acrylic, ethylene vinyl acetate, polyvinyl alcohol, methyl methacrylate, vinyl acetate and styrene-butadiene rubber.