KR102693343B1 - Eco-friendly composite mortar using mineral carbonate obtained from natural oyster pods and repair and reinforcement method of concrete structures using the same - Google Patents

Abstract

The present invention relates to an eco-friendly composite mortar using mineral carbonate obtained from natural oyster shells and a method for repairing and reinforcing concrete structures using the same, and more specifically, to a method for repairing and reinforcing concrete structures, which comprises a result obtained by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air when repairing damaged parts of deteriorated concrete structures, which captures carbon in the air during the hardening process of the mortar, thereby creating a high-strength mortar and reinforcing the structure, thereby improving durability, thereby extending the repair effect and the lifespan of the structure, and at the same time, stably completing repair work in a short period of time, thereby providing excellent economic efficiency and excellent effect in preventing neutralization of concrete, and drastically improving chemical resistance, chemical resistance, salt resistance, waterproofing, wear resistance, rust resistance and adhesive strength, thereby dramatically increasing the durability of concrete structures in chemically harsh environments such as sewers, water purification plants, underground structures, bridges, parking lots, and marine concrete structures, and reducing maintenance costs of the facilities in the long term, and also providing a carbon reduction effect. It is.

Description

{Eco-friendly composite mortar using mineral carbonate obtained from natural oyster pods and repair and reinforcement method of concrete structures using the same}

The present invention relates to an eco-friendly composite mortar using mineral carbonate obtained from natural oyster shells and a method for repairing and reinforcing concrete structures using the same, and more specifically, to a method for repairing and reinforcing concrete structures, which comprises a result obtained by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air when repairing damaged parts of deteriorated concrete structures, which captures carbon in the air during the hardening process of the mortar, thereby creating a high-strength mortar and reinforcing the structure, thereby improving durability, thereby extending the repair effect and the lifespan of the structure, and at the same time, stably completing repair work in a short period of time, thereby providing excellent economic efficiency and excellent effect in preventing neutralization of concrete, and drastically improving chemical resistance, chemical resistance, salt resistance, waterproofing, wear resistance, rust resistance and adhesive strength, thereby dramatically increasing the durability of concrete structures in chemically harsh environments such as sewers, water purification plants, underground structures, bridges, parking lots, and marine concrete structures, and reducing maintenance costs of the facilities in the long term, and also providing a carbon reduction effect. It is.

Reinforced concrete structures are generally durable and can maintain their safety and appearance for over 100 years without deterioration. However, in terms of design, materials, and construction, cracks due to drying shrinkage, insufficient concrete cover thickness, poor compaction, etc., and depending on the environment in which the concrete structure is placed after construction, large and small cracks may occur and progress in the concrete due to carbonation, salt damage, freezing damage, alkaline aggregate reaction, sulfate erosion, etc. As a result, deterioration such as concrete peeling and spalling due to corrosion of the reinforcing bars is accelerated, and in some cases, the safety of the concrete structure is lost.

Therefore, since cracks ultimately occur and progress due to various deterioration phenomena occurring in reinforced concrete structures, it is very important to accurately diagnose the cause of crack occurrence, crack width, depth, etc. for each deterioration phenomenon and apply the optimal repair and reinforcement method appropriate for it. In particular, in order to prevent re-deterioration after repair and reinforcement, it is very important to develop a systematic method that fundamentally removes the cause of deterioration.

Accordingly, it is common to carry out repairs by removing the concrete portion containing deterioration factors such as delamination or detachment of the cross-section of the structure due to deterioration of the concrete, corrosion of steel, or other causes, and then filling or spraying the section with repair reinforcing materials to restore the cross-section to its original performance and shape.

Conventional repair materials for reinforcement and repair have mainly used cement-based mortar or polymer cement mortar. Most of these conventional repair materials have focused on increasing strength or improving bonding performance during initial construction in order to suppress deterioration of existing structures and improve durability beyond the current level. Therefore, there was a problem that frequent repair work was necessary because the surface was easily damaged again shortly after construction.

For example, Korean Patent Publication No. 10-2006-0079447 proposes a method for producing a mortar composition by adding CSA (Calcium sulfoaluminate) and a predetermined fine powder binder. However, the mortar composition produced using the above material uses expensive Hauyne cement, which causes an increase in the construction cost and fails to obtain sufficient results in terms of initial setting time and strength.

In addition, when constructing using existing repair methods, moisture and oxygen seep into the tiny gaps on the surface, causing corrosion of internal reinforcing bars due to oxygen and moisture, and deterioration of concrete due to moisture, making it difficult for the repair effect to last long, so frequent repair work is required, which increases the problem of increased maintenance costs.

Meanwhile, about 400,000 tons of shellfish such as oysters, abalones, cockles, and clams are produced in Korea every year. Although some of these are used as seed shells or as raw materials for the fertilizer industry, the utilization rate is very low at less than 10%, and the added value when recycled is low, so most shellfish are discarded as reclamation of public waters or coastal storage.

Due to this, especially in fishing villages with oyster farms, shellfish pile up like mountains, causing serious environmental and marine pollution problems, and the enormous scale of the waste makes it difficult to dispose of it, and the foul odor problem is causing another environmental problem. In order to deal with this, the Ministry of Agriculture, Food and Rural Affairs and each local government are proposing various alternatives, but their effectiveness is not very high.

To solve the problem of shellfish, some technologies have been proposed to use calcium oxide obtained from shellfish as an antibacterial agent, soil conditioner, calcium reinforcing agent, acid wastewater treatment agent, building interior materials, sedimentation agent for suspended solids, steel industry materials, food raw materials, and cosmetic raw materials.

However, although much research has been conducted to apply calcium oxide obtained from shellfish to various fields, shellfish, which has become an environmental problem because its consumption is not large, still remains an unresolved problem.

[Related prior art literature]

1. Republic of Korea registered patent no. 10-1882787

2. Republic of Korea registered patent No. 10-1907917

3. Republic of Korea Publication Patent No. 10-2006-0079447

The present invention has been developed in consideration of the above-mentioned circumstances of the prior art, and the present invention aims to provide a technology capable of utilizing shellfish, which are causing serious environmental and marine pollution problems in each fishing village, as a construction material, and in particular, a technology used to repair deteriorated parts of aging concrete structures.

Specifically, the present invention provides a technology for a concrete structure repair and reinforcement method, which is characterized in that the result obtained by the reaction of carbon in the atmosphere with mineral carbonate obtained from natural oyster shells in the repair of damaged parts of deteriorated concrete structures captures carbon in the atmosphere during the hardening process of the mortar, thereby creating high-strength mortar and reinforcing the structure, thereby improving durability, thereby extending the repair effect and the lifespan of the structure, while allowing the stable completion of repair work in a short period of time, and is also economical, and has an excellent effect in preventing concrete neutralization, and significantly improves chemical resistance, salt resistance, waterproofing, wear resistance, rust resistance and adhesion, thereby dramatically increasing the service life of concrete structures in chemically harsh environments such as sewers, water purification plants, underground structures, bridges, parking lots and marine concrete structures, and can reduce the maintenance costs of the facilities in the long term, while also having a carbon reduction effect.

In order to achieve the above task, the present invention

(1) A step of repairing the cross-section of a concrete structure requiring repair or reinforcement, or cleaning the surface using a surface treatment device and cleaning the surface using high-pressure washing;

(2) A step of dehumidifying and performing injection repair on the cracked area of the concrete structure;

(3) A step of applying a primer using an eco-friendly composite mortar composition obtained by mixing mortar and water with a carbonate mineral binder formed by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air on the cross-section or surface of the concrete structure;

(4) A step of performing intermediate coating using the eco-friendly composite mortar composition on the structure on which the above-mentioned lower coating has been performed; and

(5) A method for repairing and reinforcing a concrete structure is provided, comprising: a step of applying a topcoat by spraying using a paint containing mineral carbonate obtained from natural oyster shells and fluorinated graphene fibers to a structure on which the above intermediate treatment has been performed;

In one embodiment of the present invention, the mineral carbonate obtained from the natural oyster shell of (3) is characterized in that it is obtained by sequentially immersing washed and dried natural oyster shells in acid and alcohol, heating them while immersed in water to obtain an extract, and filtering and drying the obtained extract.

In addition, in one embodiment of the present invention, the mineral carbonate obtained from the natural oyster shell of (3) is characterized in that it is structured through a two-step reaction in which it first forms a carbonic acid mineral bond through a reaction with carbon supplied from the air or the outside, and then hardens by mixing mortar and water.

In addition, in one embodiment of the present invention, the mineral carbonate obtained from the natural oyster shell of (3) is characterized in that it is calcium carbonate.

In addition, the mortar of the above (3) is characterized by using a high-strength repair mortar manufactured by mixing filler and aggregate into a binder obtained by mixing 20 to 50 wt% of fast-setting cement, 30 to 60 wt% of portland cement, 5 to 30 wt% of gypsum, and 0.1 to 5.0 wt% of calcium nitrite.

In addition, in one embodiment of the present invention, the filler is characterized by being at least one selected from limestone, lime powder, and talc.

In addition, in one embodiment of the present invention, the mortar is characterized in that it further includes at least one additive selected from 0.1 to 10 parts by weight of a dispersant, 0.01 to 3 parts by weight of a defoaming agent, and 0.01 to 10 parts by weight of a retardant, with respect to 100 parts by weight of the binder.

In addition, in one embodiment of the present invention, the fluorinated graphene fiber is characterized by using an oxidized graphene fiber whose surface is modified with fluorine.

The characteristics and advantages of an eco-friendly composite mortar using mineral carbonate obtained from natural oyster shells according to the present invention and a method for repairing and reinforcing concrete structures using the same are described as follows.

First, when repairing a deteriorated concrete structure, the service life of the structure can be extended by performing injection repair after dehumidifying the cracked concrete area, thereby reducing the maintenance cost of the structure.

In addition, by applying eco-friendly composite mortar containing mineral carbonate obtained from natural oyster shells and paint containing fluorinated graphene synthetic fibers, earthquake-resistant and flame-retardant performance can be improved, and emergency escape time can be secured in case of a fire in a structure, minimizing casualties, and preparing for earthquakes that may occur at any time, there is an effect of significantly reducing earthquake damage.

In addition, the calcium carbonate formed by the reaction of the mineral carbonate obtained from the natural oyster shells with carbon in the air can be mixed with mortar and water and hardened to strengthen the structure, thereby drastically improving the chemical resistance, salt resistance, waterproofing, wear resistance, rust resistance and adhesive strength of the structure, thereby dramatically increasing the durability of concrete structures in chemically harsh environments such as sewers, water purification plants, underground structures, bridges, parking lots and marine concrete structures, and can also contribute to the prevention of global warming due to the carbon storage effect.

Below, the present invention is described in more detail.

As described above, the present invention comprises the following steps. Namely,

(1) A step of repairing the cross-section of a concrete structure requiring repair or reinforcement, or cleaning the surface using a surface treatment device and cleaning the surface using high-pressure washing;

(2) A step of dehumidifying and performing injection repair on the cracked area of the concrete structure;

(3) A step of applying a primer using an eco-friendly composite mortar composition obtained by mixing mortar and water with a carbonate mineral binder formed by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air on the cross-section or surface of the concrete structure;

(4) A step of performing intermediate coating using the eco-friendly composite mortar composition on the structure on which the above-mentioned lower coating has been performed; and

(5) It comprises a step of applying a topcoat by spraying using a paint containing mineral carbonate obtained from natural oyster shells and fluorinated graphene fibers to the structure on which the above-mentioned intermediate coating has been applied.

Below, each step is explained in detail.

1. Floor cleaning step

In concrete structures, cracks occur in the concrete due to deterioration, etc., and over time, the compressive strength of the concrete and the tensile strength of the reinforcing steel gradually decrease, and the concrete exposed through the cracks undergoes neutralization, causing corrosion of the reinforcing steel. If such a phenomenon occurs through safety diagnosis and inspection, the cross-section or surface of the concrete structure must be repaired and reinforced to maintain the life of the building for a long time.

In order to remove laitance and foreign substances from the surface of a concrete structure, which is the target conductor, processes such as sandpaper polishing or grinding are usually performed, and dust and dirt from the surface of the structure, such as the floor or wall, are removed using a high-pressure water sprinkler.

In addition, in cases where there are many damaged areas, the cross-section is mechanically crushed and trimmed until the cracked concrete and exposed reinforcing bars are removed and undamaged concrete is obtained. At this time, it is desirable to have a rough surface on the outermost surface of the trimmed concrete so that mortar can be easily adhered.

This stage is characterized by not applying a base agent (primer) for the purpose of external waterproofing and surface reinforcement protection of the structure, but in some cases or as needed, base preparation and block adjustment using a base agent can be additionally performed. This base agent application is a process of surface-treating uneven parts of the structure's surface before painting, and it is preferable to cure the base agent for 1 to 2 days to minimize harmful effects such as temperature, load, impact, or damage.

2. Dehumidification treatment and injection maintenance stage

After the above base surface has been cleaned, moisture is completely removed using a specialized dehumidifying device.

In addition, pre-repair work is performed using an injection agent on cracked areas of the structure.

In the present invention, the injection agent may be a urea injection agent, but is not limited thereto, and various types of maintenance injection agents used in the field to which the present invention pertains may be used without limitation.

By repairing the defective areas inside the structure through this type of dehumidification treatment and injection repair, it is possible to fundamentally prevent the progression of defects inside the structure even after the lower, middle, and upper coatings using eco-friendly composite mortar.

3. Sub- and intermediate layers using eco-friendly composite mortar

The structure that has undergone the above dehumidification treatment and injection repair is repaired by applying an eco-friendly composite mortar as a repair material to the cross-section or surface and applying a base and middle coat.

In the present invention, the above-mentioned repair material uses an eco-friendly composite mortar composition obtained by mixing mortar with water and a carbonic acid mineral binder formed by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air, and this is laid and applied using a gunite spraying device.

The mineral carbonate obtained from the above natural oyster shells primarily forms calcium carbonate through a reaction with carbon present in the atmosphere (e.g., carbon dioxide) or carbon supplied externally (e.g., carbon dioxide), and the calcium carbonate thus formed is mixed into a mortar to form an eco-friendly composite mortar used in the present invention.

In the present invention, since the carbon present in the air reacts very slowly, it is preferable to inject carbon from the outside to form calcium carbonate by reaction with mineral carbonate obtained from the natural oyster shell.

The present invention is an environmentally friendly technology because it can reduce carbon, the main culprit of global warming, through a chemical reaction using such carbon.

In the present invention, the mineral carbonate obtained from the natural oyster shell is a mineral carbonate extract (e.g., calcium carbonate) extracted from the natural oyster shell, which has the function of improving resistance to fire by imparting heat resistance and flame retardancy, and at the same time, plays a role in improving earthquake resistance.

Currently, piles of discarded oyster shells are piling up along the coasts around oyster farms, causing serious environmental pollution. However, because disposal costs are high, they cannot be disposed of, and they continue to pile up.

The present invention aims to suggest a method for utilizing waste oyster shells as a resource by providing a technology for utilizing such waste oyster shells in the construction field.

In the present invention, the mineral carbonate obtained from the natural oyster shell is obtained by sequentially immersing washed and dried natural oyster shells in acid and alcohol, heating the immersed shells in water to obtain an extract, and filtering and drying the obtained extract.

Specifically, first, the internal organs and fleshy parts are completely removed, and the washed and dried oyster shells are immersed in an acid solution and then in an alcohol solution. At this time, it is preferable to use an acid concentration of about 10 to 20 wt%, and the immersion time is appropriate for about 4 to 10 hours.

Additionally, methanol or ethanol can be used as alcohol, and it is recommended that the immersion time be 1 to 5 hours.

After the oyster shells are soaked, they are then heated while immersed in water.

When oyster shells are heated, the decomposition products begin to separate, and when they reach a certain concentration, they settle to the bottom.

Such a precipitate is an extract containing about 10 to 30 wt % of mineral carbonates (e.g. calcium carbonate).

The above extract is washed, filtered and dried to obtain a powder, which can be used to form calcium carbonate by reaction with carbon according to the present invention.

The mortar using the mineral carbonate obtained from the natural oyster shell according to the present invention has excellent flame retardancy and fire resistance, and further has the effect of increasing water resistance and chemical resistance.

Next, the obtained calcium carbonate is mixed with water in a repair mortar to form an eco-friendly composite mortar composition.

In the present invention, the mortar is characterized by using a high-strength repair mortar manufactured by mixing filler and aggregate into a binder obtained by mixing 20 to 50 wt% of fast-setting cement, 30 to 60 wt% of portland cement, 5 to 30 wt% of gypsum, and 0.1 to 5.0 wt% of calcium nitrite.

Specifically, it is preferable to use the above-mentioned fast-setting cement containing 20 to 50 parts by weight of a slag-containing mixture and 20 to 40 parts by weight of dihydrate gypsum phosphate.

The present invention uses gypsum mixed with the obtained fast-setting cement.

That is, when only the above-mentioned rapid-setting cement is used, the curing time is fast and initial shrinkage occurs, so by mixing and using gypsum that has a hydration speed similar to that of the rapid-setting cement and expandability, the curing shrinkage can be reduced compared to when only the rapid-setting cement is used due to the complementary effect between them. Therefore, the initial cracking can be prevented and the initial strength can be further improved compared to when the rapid-setting cement is used alone.

Additionally, in the present invention, calcium nitrite powder is mixed and used to protect rebar.

It is preferred to use the above calcium nitrite powder having a specific surface area of 1,000 to 8,000 cm ² /g.

The above calcium nitrite powder promotes the hydration reaction with C3A contained in cement and increases the amount of ettringite produced, thereby contributing to enhancing the initial strength of mortar. In addition, since the above calcium nitrite powder plays a role in protecting the internal reinforcing bars, the process of separately applying a reinforcing bar rust inhibitor after chipping can be omitted.

The above calcium nitrite powder is preferably included in the binder at 0.1 to 5.0 wt%. If the amount used is less than 0.1 wt%, the hydration promotion and reinforcing bar protection effects are reduced, and if it exceeds 5.0 wt%, the fluidity of the mortar is reduced, which may result in poor workability.

The present invention uses a repair mortar composition prepared by mixing 20 to 50 wt% of rapid-setting cement, 30 to 60 wt% of portland cement, 5 to 30 wt% of gypsum, and 0.1 to 5.0 wt% of calcium nitrite to prepare a binder, and then mixing filler and aggregate into the binder and mixing it with water.

In addition, for the purpose of repairing and reinforcing underwater concrete structures, an underwater anti-separation agent may be additionally included in the range of 0.1 to 3 wt%. The underwater anti-separation agent is added to improve the viscosity of the mortar composition in water and prevent it from being decomposed, and a cellulose-based thickener selected from methyl cellulose such as methyl cellulose, hydroxymethyl cellulose, and carboxymethyl cellulose; ethyl cellulose such as ethyl cellulose, hydroxyethyl cellulose, and carboxyethyl cellulose; and propyl cellulose such as hydroxypropyl cellulose can be used. It is preferable to use the content of 0.1 to 3 wt% because it exhibits an appropriate viscosity. If necessary, a water-soluble acrylic resin powder may be further added to further increase the viscosity in water. It is preferable to use the water-soluble acrylic resin powder in an amount of 1 to 30 wt% with respect to 100 wt% of the underwater anti-separation agent.

In the present invention, the fast-setting cement manufactured by the above method forms calcium sulfoaluminate and calcium aluminate by mixing cement as a source of CaO, gypsum phosphate as a source of CaSO ₄ , and calcium nitrite powder having a reinforcing bar protection effect in the above mixing ratio. When the calcium sulfoaluminate is mixed with water, it mainly produces ettringite or calcium hydroxide through a hydration reaction, thereby promoting hydration. In addition, the ettringite of the needle-shaped crystals produced through the hydration reaction fills the micropores of cement mortar and concrete to develop strength or cause expansion, thereby making it possible to manufacture mortar with excellent strength and a fast hardening speed. The calcium aluminate is a general term for substances having hydration activity whose main components are CaO and Al ₂ O ₃ . Specifically, the calcium aluminate reacts with water to form various calcium aluminate hydrates, and since the reaction occurs quickly in the early stage, a mortar composition exhibiting fast hardening can be produced.

In the present invention, it is preferable to use the fast-setting cement in an amount of 20 to 50 wt% of the total binding agent components. If it is less than 20 wt%, the mortar strength is reduced and a fast curing time cannot be obtained. If it exceeds 50 wt%, fast curing characteristics can be obtained, but cracks may occur due to excessive expansion caused by interaction with alpha-type hemihydrate gypsum.

In the present invention, among the binding components, portland cement is used to develop the later strength of the mortar. It is preferable to use type 1 portland cement, and it is preferable to use 30 to 60 wt% of the total binding components.

In the present invention, among the binding components, gypsum is used to produce a large amount of ettringite, which reacts with rapid-hardening cement at the initial stage of hydration to exhibit initial strength and expansion of the mortar, thereby preventing cracks due to excellent compressive strength and shrinkage. It is preferable to use 5 to 30 wt% of the total binding components. If it is less than 5 wt%, it is difficult to exhibit rapid-hardening or expansion properties of the mortar, and if it exceeds 30 wt%, it may cause cracks due to excessive expansion and an increase in the price of raw materials.

In the present invention, the binder composed of the above-described fast-setting cement, portland cement, gypsum, and calcium nitrite is preferably included in an amount of 20 to 50 wt% in a mortar composition for repairing concrete structures. If it is used in an amount of less than 20 wt%, initial strength and adhesive strength may decrease, and if it exceeds 50 wt%, initial cracks may occur due to rapid hardening and high hydration heat generation during use.

In the present invention, the filler may be at least one selected from limestone, limestone powder, and talc, and it is preferable to use the content in the range of 5 to 20 wt%. If it is less than 5 wt%, the effect of suppressing shrinkage of the hardened body is insignificant, and there is a concern that the drying shrinkage amount may increase, and if it exceeds 20 wt%, the amount of filler becomes excessive, which may deteriorate fluidity and workability.

In the present invention, the aggregate having a particle size of 0.2 mm to 2.5 mm is preferable because it is suitable for producing a mortar that does not separate from each other and has good adhesiveness. Considering the workability of the mortar, the aggregate preferably has a proportion of 40 to 70 wt% with respect to the entire mortar.

In addition, the present invention may further include, if necessary, one or more additives selected from 0.1 to 10 parts by weight of a dispersant, 0.01 to 3 parts by weight of a defoaming agent, and 0.01 to 10 parts by weight of a retardant, per 100 parts by weight of the binder.

The above dispersant is adsorbed on the surface of mortar particles and provides a charge to the particle surface to cause a repulsive force between the particles, thereby dispersing the agglomerated particles to increase flow and enabling strength enhancement due to the water reducing effect. A typical water reducing agent can be used as the above dispersant, and for example, a single agent or a mixture of two or more agents selected from the group consisting of lignin sulfonate, polynaphthalene sulfonate, polymelamine sulfonate or polycarboxylate water reducing agents can be used. The content of the dispersant is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the binder, and when it is used in an amount less than 0.1 parts by weight, the above performance is not exhibited, and when it exceeds 10 parts by weight, the mortar viscosity decreases due to excessive use, which has the disadvantage of causing material separation.

The above-mentioned defoaming agent is used to improve the strength and appearance of the mortar by removing large pores in the mortar. The defoaming agent includes mineral oil-based defoaming agents such as kerosene and liquid paraffin; fat-based defoaming agents such as animal and vegetable oils, sesame oil, castor oil, and alkylene oxide adducts thereof; fatty acid-based defoaming agents such as oleic acid, stearic acid, and alkylene oxide adducts thereof; fatty acid ester-based defoaming agents such as glycerin monoricinoleate, alkenyl succinic acid liquid, sorbitol monolaurate, sorbitol trioleate, and natural waxes; Oxyalkylene-based defoaming agents such as polyoxyalkylenes, (poly)oxyalkyl ethers, acetylene ethers, (poly)oxyalkylene fatty acid esters, (poly)oxyalkylene sorbitan fatty acid esters, (poly)oxyalkylene alkyl (aryl) ether sulfate ester salts, (poly)oxyalkylene alkyl phosphate esters, (poly)oxyalkylene alkyl amines, (poly)oxyalkylene amides, etc.; alcohol-based defoaming agents such as octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols, etc.; amide-based defoaming agents such as acrylate polyamines, etc.; phosphate ester-based defoaming agents such as tributyl phosphate and sodium octyl phosphate; metal soap-based defoaming agents such as aluminum stearate and calcium oleate, etc. A silicone-based defoaming agent such as dimethylsilicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil, etc. can be used. It is preferable to use 0.01 to 3 parts by weight of the defoaming agent based on 100 parts by weight of the binder. If it is used in an amount of less than 0.01 parts by weight, the performance of removing air bubbles generated during stirring is significantly reduced. If it exceeds 3 parts by weight, there is a disadvantage of reducing the strength of the composition.

The above retarder can be added for the purpose of adjusting the hydration speed of the binder to ensure workability for a certain period of time. Examples of the retarder include: boric acid, borax, sodium borate, potassium borate, and other borates; oxycarboxylic acids such as gluconic acid, citric acid, tartaric acid, glucoheptonic acid, arabic acid, malic acid, and citric acid, and inorganic or organic salts thereof such as sodium, potassium, calcium, magnesium, ammonium, and triethanolamine; monosaccharides such as glucose, fructose, galactose, saccharose, xylose, abitose, lipose, and isomerized sugars; oligosaccharides such as disaccharides and trisaccharides; oligosaccharides such as dextrin, or polysaccharides such as dextran; sugars containing these, such as molasses; sugar alcohols such as sorbitol; magnesium silicofluoride; phosphoric acid and its salts or boric acid esters; aminocarboxylic acids and their salts; Alkali-soluble proteins; fumic acid; tannic acid; phenol; polyhydric alcohols such as glycerin; phosphonic acids and derivatives thereof such as aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and alkali metal salts and alkaline earth metal salts thereof can be used. It is preferable to add 0.01 to 10 parts by weight based on 100 parts by weight of the binder.

In the present invention, an eco-friendly composite mortar including the high-strength repair mortar composition is applied to the outermost surface of a cross-section of a structure, and a lower and middle coat are applied. At this time, it is preferable to apply the lower coat to a thickness of about 5 to 15 mm and the middle coat to a thickness of 20 to 50 mm, but the thickness can be changed depending on the condition of the concrete.

In addition, in the present invention, when laying and applying the eco-friendly composite mortar, a gunite spraying device is used to apply the base and middle coats.

The above guniting spraying equipment is equipped with an accelerator and is equipment for spraying concrete or mortar using a high-pressure spraying system for construction, and in the present invention, it is used for the lower and middle coatings of mortar and for finishing.

Specifically, the above-mentioned gunite equipment is preferably grounded gunite equipment for safe construction, and is preferably equipped with a double movable height-adjustable propeller impeller, an integrated air fan equipped with a nano filler, a power rotary mortar, insulated and explosion-proof equipment, and lighting.

4. Painting with commercial paint

After applying the above eco-friendly composite mortar to the concrete crushed area, finishing it smoothly and drying it, elastic putty can be applied to the micro-cracks caused by shrinkage cracks and gaps that exist at the boundary between the newly applied repair material and the existing concrete structure.

In the present invention, a silicone-based elastic putty and a method of securing breathability by adding a certain amount of aerogel to the elastic putty can be used.

After the above putty work, the surface of the structure can be painted with a topcoat according to the present invention.

In the present invention, the surface coating is a paint containing mineral carbonate obtained from the natural oyster shell and fluorinated graphene fibers. The paint may be an acrylic paint, a urethane paint or a urea paint, and may be a one-component or two-component type.

The mineral carbonate obtained from the above natural oyster shell, as described above, when included in a paint, improves resistance to fire by imparting heat-resistant and flame-retardant performance, and at the same time plays a role in improving earthquake-resistant performance.

In addition, the fluorinated graphene fibers in the present invention are oxidized graphene fibers whose surface is modified with fluorine, and have the function of improving the waterproofness, fire resistance, and heat resistance of the paint.

Specifically, the surface-modified graphene oxide fibers with the above fluorine induce covalent bonding between the graphene oxide and the paint resin, so that the graphene within the paint film is uniformly dispersed in cracks, thereby exhibiting excellent waterproofing properties, heat resistance properties, and fire resistance properties.

The above-mentioned oxide graphene may be single-layer oxide graphene or graphite in which oxide graphene is stacked in several to several tens of layers, and such oxide graphene may be manufactured through a process of exfoliating graphite using a strong agent and an oxidizing agent. The oxide graphene may be manufactured at a reduced cost compared to graphene or reduced oxide graphene, and during the exfoliation process, oxygen functional groups such as hydroxyl groups are formed on the oxide graphene, making it easy to subsequently modify the surface with a fluorinated substance, and has the advantage of being able to be uniformly dispersed.

The coating composition according to the present invention may additionally contain a ceramic pigment to prevent internal corrosion due to the intrusion of acidic corrosion particles.

In the present invention, the ceramic pigment is prepared by mixing 5 to 40 wt% of mica having a particle size of 1 to 100 ㎛, 10 to 50 wt% of lime powder, 5 to 50 wt% of emulsion, 10 to 70 wt% of water, and 1 to 10 wt% of pigment, and can be used by including it in a range of 0.1 to 5 wt% based on 100 wt% of the topcoat.

In the present invention, the mica can be used in the form of flakes or powder, and when mica having the above particle size is used, adhesion to a conductor can be improved.

In addition, in the present invention, the stone powder may be a commonly used stone powder, or may be used by crushing natural stone or artificial stone. The stone powder may have a particle size similar to mica, and this serves to improve the adhesiveness with the conductor.

In the present invention, the emulsion may be ammonia or amine, and less toxic emulsion paint, water-soluble paint, etc. may also be used.

In addition, in addition to the method of mixing pigments as a method for imparting color, the surface of mica may be coated in advance using pigments. Specifically, a pigment such as an inorganic pigment or an organic pigment may be mixed and kneaded into mica to coat the surface of the mica with the pigment, and the mica coated with the pigment may be fired or hardened and cooled to impart color.

In addition, the present invention may additionally include a flexible resin to prevent the surface to be painted and the surface to be painted from being separated over a long period of time. The flexible resin can increase the flexibility of the surface to be painted, thereby further improving the adhesiveness. As the flexible resin used at this time, acrylic resin, methacrylic resin, urethane resin, phenoxy resin, styrene resin, natural rubber, SBR, NBR, etc. can be used, and it is preferable that the amount used is 0.01 to 1.0 weight part based on 100 weight parts of the main component.

In addition, various additives may be included within a range that does not impair the effects of the present invention, and the additives may further include additives such as dispersants, thickeners, anti-foaming agents, pigments, pH regulators, anti-freezing agents, preservatives, and antioxidants. It is preferable that such additives be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the topcoat.

In addition, in the present invention, the coating material can exhibit heat-insulating performance by using one that includes heat-insulating powder.

In the present invention, the heat-insulating powder effectively reflects infrared rays that generate heat energy in sunlight, thereby inhibiting the infrared rays from being converted into heat energy.

In the present invention, the heat-insulating powder may be, for example, at least one metal oxide selected from the group consisting of antimony tin oxide, indium tin oxide, cesium tungsten oxide, and antimony trioxide-zinc oxide.

The above heat-insulating powder may be in the form of particles such as spheres, rods, needles, etc., or in a hollow shape, and it is preferable to use one having an average particle size of 2 to 100 nm.

In the present invention, it is preferable that the heat-insulating powder is included in the topcoat paint in a range of 0.1 to 5 parts by weight.

In the present invention, the first topcoat is applied by brush painting and the second topcoat is applied by spray painting, so that preliminary painting can be performed on areas where spray painting is difficult, such as corners, floor and wall boundaries, and joints, and then painting can be performed by spraying using the ultra-fast curing method. Accordingly, the topcoat can be applied densely without any missing areas, so that a complete waterproofing protection effect can be achieved.

Above, the repair and reinforcement method of a concrete structure according to the present invention has been described in detail.

The earthquake-resistant repair and reinforcement construction method of a structure according to the present invention can extend the service life of a structure by performing injection repair after dehumidification of a concrete crack area when repairing a deteriorated concrete structure, thereby reducing the maintenance cost of the structure, and can improve earthquake-resistant performance and flame-retardant performance by applying an eco-friendly composite mortar containing mineral carbonate obtained from natural oyster shells and a paint containing fluorinated graphene synthetic fibers, and can secure emergency escape time in the event of a fire in the structure, thereby minimizing casualties, and can significantly reduce earthquake damage by preparing for an earthquake that may occur at any time, and can strengthen the structure by mixing calcium carbonate formed by the reaction of the mineral carbonate obtained from the natural oyster shells with carbon in the air with mortar and water and hardening it, thereby significantly improving the chemical resistance, chemical resistance, salt resistance, waterproofing, wear resistance, rust resistance, and adhesive strength of the structure, making it suitable for use in chemically poor environments such as sewers, water purification plants, underground structures, bridges, parking lots, and marine concrete structures. It can dramatically increase the durability of concrete structures under environmental conditions, and can also contribute to preventing global warming due to its carbon storage effect.

Hereinafter, the present invention will be described in more detail based on examples. However, the scope of the present invention is not limited by the following examples.

[Example]

(Example 1)

(1) Surface preparation work: The deteriorated parts of the cross-section and surface of the concrete structure to be coated were removed using chipping equipment and surface treatment equipment (e.g., sandpaper polishing), and dust and dirt on the surface of the structure were removed using a high-pressure sprinkler.

(2) Repair of structural defects: After the surface cleaning work described above, defective parts of the structure (e.g., cracked parts) were discovered and repairs were performed using an injection agent. In addition, moisture was completely removed using a special dehumidifying device.

(3) Application of base and intermediate coats: An eco-friendly composite mortar composition obtained by mixing calcium carbonate and mortar formed by the reaction of mineral carbonate obtained from natural oyster shells and carbon dioxide in the air with water was applied as base and intermediate coats on the surface on which the above surface treatment work was performed using gunite spray equipment.

At this time, the mineral carbonate obtained from the natural oyster shell was used by soaking the washed and dried waste oyster shell in acid and alcohol for 5 hours and 3 hours, respectively, and then heating it while soaking it in water to obtain a precipitate (extract), and filtering and drying the obtained extract.

The above mortar was obtained by mixing filler and aggregate into a binder obtained by mixing 30 wt% of fast-setting cement, 45 wt% of portland cement, 23 wt% of gypsum, and 2.0 wt% of calcium nitrite.

(4) Topcoat coating: After the above eco-friendly composite mortar was applied and hardened, the surface was topcoat-coated using an acrylic paint containing mineral carbonate obtained from natural oyster shells and fluorinated graphene fibers by spraying.

The above fluorinated graphene fibers were used by mixing a certain amount of oxidized graphene fibers whose surface was modified with fluorine.

(Comparative Example 1)

The same procedure as Example 1 was carried out, but using the mortar for the lower and middle layers.

Based on 100 parts by weight of cement, 1.5 parts by weight of vinyl acetate polymer, 0.2 parts by weight of expansive agent, 1.5 parts by weight of polycarboxylic acid type superplasticizer, and 100 parts by weight of silica are included, and additives are mixed to form the mortar. The cement is mixed in a weight ratio of 40 of portland cement, 35 of early-strength cement, and 30 of slag cement, and the silica is different only in that the mortar is obtained by using recycled aggregate having an average particle size of 0.3 to 1.5 mm.

(Comparative Example 2)

The same procedure as Example 1 was carried out, but using the mortar for the lower and middle layers.

A mortar comprising 13 parts by weight of fiber, 1.5 parts by weight of vinyl acetate polymer, 0.2 parts by weight of expandable agent, 1.5 parts by weight of polycarboxylic acid type superplasticizer, and 100 parts by weight of silica based on 100 parts by weight of cement, and mixed with additives, wherein the cement is mixed in a weight ratio of 40 of portland cement, 35 of early-strength cement, and 30 of slag cement, and the silica is different only in that a mortar obtained by using recycled aggregate having an average particle size of 0.3 to 1.5 mm is used.

(Comparative Example 3)

The same procedure as in Example 1 was followed, except that a two-component urethane paint was used, obtained by mixing 30 parts by weight of acrylic urethane resin, 20 parts by weight of silane, 3 parts by weight of wax, 5 parts by weight of bentonite, 2 parts by weight of urethane accelerator, 2.0 parts by weight of dispersant, 5 parts by weight of calcium carbonate, 5 parts by weight of extender pigment, and other additives.

[Performance Evaluation]

(1) Properties of mortar composition

Test specimens were manufactured using the mortar compositions manufactured in the above examples and comparative examples, and their physical properties were measured using the following test methods.

1) Coagulation time: KSF 2436

2) Flexural strength: KS F 2476 “Strength test method for polymer cement mortar”

3) Compressive strength: KSF 2405

4) Bonding strength: KS F 4716 “Strength test method for polymer cement mortar”

5) Length change rate: Measured according to KS F 2424, Length change test method for mortar and concrete. The value is set to 0 for the initial construction body, “-” indicates shrinkage rate, and “+” indicates expansion rate.

6) Flow: Conducted in accordance with KS L 5220.

The results are shown in Table 1 below.

item Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Congealing time (minutes) Super resolution 30 36 39 28 closing 39 55 60 35 Bending strength
(N/mm ² ) gin 31 15 13 29 Underwater 24 12 10 25 Compressive strength
(N/mm ² ) gin 80 54 49 79 Underwater 74 49 42 73 Bonding strength
(N/mm ² ) gin 8.5 3.7 3.5 8.7 Underwater 6.1 1.7 1.4 6.1 Length change rate (%) +0.005 +0.05 +0.03 +0.005 Flow (mm) 101 150 141 108

As shown in Table 1 above, the eco-friendly composite mortar according to the present invention has significantly superior physical properties compared to conventional mortar compositions, and in particular, it can be confirmed that the flexural strength, compressive strength, and bond strength in air and underwater are significantly superior, and the length change rate also provides significantly relatively superior performance.

(2) Evaluation of cross-sectional recovery performance

1) Weather resistance evaluation

Measured for 400 hours according to ASTM G 155.

2) Surface hardness evaluation

Pencil hardness was measured according to KS D 6711.

3) Water resistance evaluation

The time required for continuous surface deformation (cracking, blistering, etc.) to occur in 120℃ hot water was measured.

The results of the above evaluation are shown in Table 2.

Weatherproof (white) Surface hardness Water resistance Example 1 △E1.8 6H 890hr Comparative Example 1 △E2.2 4H 550hr Comparative Example 2 △E3.2 4H 480hr Comparative Example 3 △E2.0 6H 820hr

From the results in Table 1 and Table 2 above, it can be confirmed that when the eco-friendly composite mortar according to the present invention is used for cross-sectional repair and reinforcement construction, the mortar has excellent performance, excellent adhesion to concrete, and excellent physical properties such as weather resistance and water resistance, so that repair and reinforcement of underground concrete structures can be efficiently performed, thereby enhancing the long-term durability of the repair and reinforcement.

As described above, the present specification has disclosed preferred embodiments of the present invention, and although specific terms have been used, they have been used in a general sense only to easily explain the technical contents of the present invention and to help understand the invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modified examples based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims (8)

(1) A step of repairing the cross-section of a concrete structure requiring repair or reinforcement, or cleaning the surface using a surface treatment device and cleaning the surface using high-pressure washing;
(2) A step of dehumidifying and performing injection repair on the cracked area of the concrete structure;
(3) A step of applying a primer using an eco-friendly composite mortar composition obtained by mixing mortar and water with a carbonate mineral binder formed by a reaction between mineral carbonate obtained from natural oyster shells and carbon in the air on the cross-section or surface of the concrete structure;
(4) A step of performing intermediate coating using the eco-friendly composite mortar composition on the structure on which the above-mentioned lower coating has been performed; and
(5) A method for repairing and reinforcing concrete structures, comprising: a step of applying a topcoat by spraying using a paint containing mineral carbonate obtained from natural oyster shells and fluorinated graphene fibers to the structure on which the above intermediate treatment has been performed;
A method for repairing and reinforcing concrete structures according to claim 1, characterized in that the mineral carbonate obtained from the natural oyster shell of the above (3) is obtained by sequentially immersing washed and dried natural oyster shells in acid and alcohol, heating the immersed shells in water to obtain an extract, and filtering and drying the obtained extract.
A method for repairing and reinforcing a concrete structure, characterized in that in claim 1, the mineral carbonate obtained from the natural oyster shell of (3) first forms a carbonic acid mineral bond through a reaction with carbon supplied from the air or the outside, and then hardens by mixing mortar and water, thereby forming a structure through a two-step reaction.
A method for repairing and reinforcing a concrete structure, characterized in that the mineral carbonate obtained from the natural oyster shell of claim 1 (3) is calcium carbonate.
A method for repairing and reinforcing concrete structures, characterized in that in claim 1, the mortar of (3) is a high-strength repair mortar manufactured by mixing filler and aggregate into a binder obtained by mixing 20 to 50 wt% of fast-setting cement, 30 to 60 wt% of portland cement, 5 to 30 wt% of gypsum, and 0.1 to 5.0 wt% of calcium nitrite.
A method for repairing and reinforcing a concrete structure, characterized in that in claim 5, the filler is at least one selected from limestone, lime powder, and talc.
A method for repairing and reinforcing a concrete structure according to claim 5, characterized in that the mortar further contains at least one additive selected from 0.1 to 10 parts by weight of a dispersant, 0.01 to 3 parts by weight of a defoaming agent, and 0.01 to 10 parts by weight of a retardant, with respect to 100 parts by weight of the binder.
A method for repairing and reinforcing a concrete structure according to claim 1, characterized in that the fluorinated graphene fibers use oxidized graphene fibers whose surface is modified by fluorine.