KR102342438B1 - Mortar composition and repair-reinforcement method using the same - Google Patents

Abstract

A mortar composition of the present invention comprises: 20-40 wt% of any one or more cement selected from a group consisting of general cement, slag cement, and Portland cement; 5-20 wt% of a super water repellent including alkoxysilane and/or acetoxysilane in which at least one adhesive selected from a group consisting of epoxy, polyurethane, and acrylic urethane and silica aerogel of nanoparticles having a particle diameter of 10-1000 nanometers are dispersed at a weight ratio of 5: 1-1: 1; 3-15 wt% of an expansion material; 5-20 wt% of a filling material; 20-55 wt% of particle size adjustment silica; 0.2-1 wt% of any one of fluidizing agent selected from a group consisting of melamine-based, naphthalene-based, and carboxyl-based fluidizing agents; 0.05-2 wt% of a reactivity regulator; and 0.2-3 wt% of a stabilizer consisting of at least one of calcium-based, barium-based, zinc-based, and magnesium-based stearate. A method for repairing and reinforcing a cross section of an underwater concrete structure comprises: a preparing step of digging an underwater lowest surrounding unit and cleaning a repaired object part with high pressure; a step of installing a stand on the outer surface of the underwater concrete structure and measuring a status of the repaired object part; a step of installing a reinforcing frame by being separated at a predetermined distance along the outer surface of the underwater concrete structure; a step of placing mortar in a separation space between the underwater concrete structure and the reinforcing frame; and a step of filling the mortar in a digging part of a surrounding unit of the concrete structure in which the reinforcing frame is installed and hardening the same.

Description

Mortar composition with excellent adhesion on wet and dry surfaces and cross-section repair and reinforcement method using the same

The present invention relates to a mortar composition having excellent adhesion on a wet surface and a dry surface, and a cross-section repair and reinforcement method using the same, specifically for repairing and reinforcing damage to a damaged part of a reinforced concrete structure submerged in water or a reinforced concrete structure As a mortar composition, it relates to a mortar composition having excellent adhesion, especially on a wet and dry surface, and a cross-section repair and reinforcement method that uses the same to quickly restore damaged and lost cross-sections and strengthen adhesion and adhesion.

Considering the prevention of corrosion caused by the strong alkaline concrete itself in the construction of domestic and overseas ports and bridges, various types of concrete composition and structural reinforcement compositions and repair methods used for repair and improvement work are being developed.

Existing or new structures used in ports and bridges are mostly reinforced concrete structures. In terms of safety, durability, and lifespan, prevention and solution of serious underwater damage to concrete due to corrosion of internal rebars are particularly difficult in facilities that come into contact with water. very important.

In Korea, a large amount of budget is being invested in corrosion prevention, underwater damage prevention, and maintenance of underwater damaged parts in these underwater facilities.

Underwater concrete structures receive structurally concentrated loads or cracks due to shocks or other stimuli. Water penetrates into the cracks, and internal rebars corrode intensively, leading to gradual damage to the concrete.

Corrosion refers to the unwanted oxidation of metals. In particular, when iron among metals corrodes, it comes off the surface and continues to corrode, impairing the safety of the entire structure and causing accidents.

In the natural state, iron (Fe) is mainly combined with oxygen and exists in the most stable state in the ore, but when electric or thermal energy is applied, it becomes metal ionized and becomes thermodynamically unstable. At this time, it is exposed to an environment with water and air (oxygen) When the reaction proceeds as follows, it ^{is oxidized to Fe 3+} to become a hydrate (rust) of iron oxide.

Anode reaction Fe → Fe ²⁺ + 2e ^-

Fe ²⁺ + 2OH ^- → Fe(OH) ₂ ferrous hydroxide is formed

Fe(OH) ₂ + 1/2H ₂ O + 1/4O ₂ → Fe(OH) ₃ ferric hydroxide

Cathodic reaction H ₂ O + 1/2O ₂ + 2e ^- → 2OH ^- oxygen reduction

1/2O ₂ + 2H ⁺ + 2e ^- → H ₂ O

2H ⁺ + 2e ^- → H ₂ hydrogen production

In addition, the surface of the reinforcement in the reinforced concrete structure is covered with a protective film called a passivation film, and is protected from corrosion in an alkaline environment.

However, due to the intrusion of chloride and water or due to the neutralization of concrete, chloride ions destroy the passivation film and cause corrosion.

Corrosion of reinforcing bars in concrete increases to 2-3 times its original volume due to rust, and accordingly, it causes cracks in the clad concrete by the expansion pressure. This can cause peeling and dropping of surface concrete, reduced adhesion to reinforcing bars, and reduced strength, which can also cause the collapse of the concrete structure itself.

In addition, due to the characteristic difficulty in the process of repair and reinforcement in water, the adhesive force between the wet and dry surfaces is significantly lower than during repair and reinforcement on land, so there is a problem that the efficiency of the work and the results of the repair work are significantly worse. .

Therefore, the repair of the deteriorated part of the existing underwater concrete structure is carried out safely in consideration of the very difficult environment for underwater work, while preventing damage due to subsequent re-corrosion and working quickly and quickly through this, In order to increase the reconstruction rate and reinforcing power of the underwater concrete structure, it should be performed with a highly reliable repair and reinforcement method.

Therefore, it is necessary to develop materials for repair and reinforcement for internal rebar or concrete deterioration and corrosion of underwater concrete structures, and to develop a method for repairing and reinforcing underwater concrete structures that is safe and easy to work with and can prevent post-damage and environmental pollution. do.

In order to solve the above problems, the present invention is to develop a mortar for water hardening for rapid and safe repair and reinforcement in water, with strong adhesion between the wet and dry surfaces from corrosion of underwater concrete structures and concrete rupture.

In addition, another object of the present invention is to propose a safe and easy construction method for the repair and reinforcement of the destruction, corrosion, or deterioration of the concrete structure in the water, so that the adhesion is strengthened from further re-corrosion or environmental pollution of the concrete structure even after the repair work. It extends to proposing a repair and reinforcement method for underwater concrete structures that can be maintained as a structure.

The main component of the mortar composition according to an embodiment of the present invention may be cement, a super water-repellent curing agent, an expansion material, a filler, silica sand, a fluidizing agent, a reactivity modifier, and a stabilizer.

Specifically, since it is an underwater hardening mortar used to repair and reinforce the inner surface of an underwater concrete structure, it is configured to include the following composition ratio to strengthen the adhesion between the wet and dry surfaces.

That is, 20 to 40 wt% of any one or more cements selected from the group consisting of general cement, slag cement, and Portland cement, and any one or more adhesives selected from the group consisting of epoxy, polyurethane, and acrylic urethane and particle diameters of 10 to 1000 nanometers Metric nanoparticles of silica airgel are dispersed in a weight ratio of 5:1 to 1:1, 5 to 20 wt% of a super water-repellent curing agent containing alkoxysilane and/or acetoxysilane, 3 to 15 wt% of an expander, 5 to 20 wt% of a filler %, particle size adjustment 20 to 55wt% of silica sand, 0.2 to 1wt% of any one fluidizing agent selected from the group consisting of melamine-based, naphthalene-based, and carboxyl-based fluidizing agents, 0.05 to 2wt% of reactivity modifier, and calcium-based, barium-based, ah It may contain 0.2 to 3 wt% of a stabilizer consisting of any one or more of linkages, and magnesium-based stearate.

In another embodiment of the present invention, the mortar composition may further include a nano-carbon material or boron nitride in order to increase rigidity in addition to the above main components. Specifically, 0.01 to 3 wt% of at least one nano-carbon material or boron nitride (BN) selected from the group consisting of multi-wall carbon nanotubes, bundled carbon nanotubes, carbon nanoplates, plate-shaped graphite, graphene, and graphene oxide may include more.

In the present invention, the super water-repellent curing agent is characterized in that the adhesive and the silica airgel are dispersed in an anionic or non-ionic dispersant in an amount of 0.5 to 3 wt % based on the weight of the super water-repellent curing agent in an organic solvent.

In addition, the particle size of the silica airgel is not necessarily limited, but may be in the range of nanometers to micrometers, preferably 10 to 1000 nanometers, and more preferably 10 to 20 nanometers.

In one embodiment of the present invention, the expansion material is calcium sulfo-aluminate (CSA), gypsum, calcium oxide (Ca0), calcium sulfate (CaSO ₄ ), alumina cement (Alumina cement), and calcium aluminate ( It may be any one or more selected from the group consisting of calcium aluminate) hydrate.

In addition, the filler may be any one or more selected from the group consisting of fine silica powder, slag fine powder, fly ash fine powder, metakaolin fine powder, calcium carbonate (CaCO ₃ ) and/or _{fine clay containing titanium dioxide (TiO 2 ),} Preferably, it may be two or more fillers including slag fines.

wherein the fine clay is selected from the group consisting of bauxite, gibzite, diaspore, boehmite, amorphous hydrous alumina, limonite, quartz, feldspar, halloysite, kaolinite, nontronite, laterite, montmorillonite, bentonite It may be at least one, but is not necessarily limited thereto.

In addition, the particle size adjustment silica sand may be composed of 40 to 60 wt% of the particle size No. 5 silica sand and 60 to 40 wt% of the particle size No. 6 silica sand, but this is also not necessarily limited.

In the mortar composition according to an embodiment of the present invention, the reactivity modifier may be at least one selected from the group consisting of citric acid, sodium gluconate, tartaric acid, silicofluoride, methylcellulose, ethylcellulose, and boric acid.

The repair and reinforcement method of an underwater concrete structure using an underwater hardening mortar according to another embodiment of the present invention includes the preparation step, installation of the cradle and the measurement of the condition of the part to be repaired, the production and installation step of the reinforcement frame, the mortar pouring step, the finishing step after curing can be composed of

The preparation stage is the process of excavating the lowest periphery of the underwater concrete structure and high-pressure washing of the repair target area.

The stage of installing the cradle and measuring the status of the part to be repaired is a process of going down to the water, installing the cradle outside the underwater concrete structure to arrange the surrounding area, and measuring the number and condition of the part to be repaired in the underwater concrete structure in detail.

The reinforcing frame may be installed to be spaced apart from each other at predetermined intervals along the outer surface of the underwater concrete structure.

Then, a pouring process of injecting mortar for underwater hardening into the space between the underwater concrete structure and the reinforcing frame is performed. The water-curing mortar may have the composition quality and composition ratio as described above, but is not necessarily limited thereto.

After the water hardening mortar is hardened and hardened, the underwater hardening cement or the water hardening mortar according to an embodiment of the present invention is additionally filled in the excavation part of the periphery of the concrete structure in which the reinforcement frame is installed, and then the water hardening mortar is filled and finished.

In one embodiment, the step of installing the reinforcing frame includes: a first step of disposing a plurality of reinforcing plates spaced apart from the outer surface of the concrete structure by a predetermined distance and fixing the connecting portions of the reinforcing plates to each other with fixing pins; A second step of maintaining the separation distance by a support member connecting the outer surface of the concrete structure and the plurality of reinforcing plates through a hole in the second step, and repeating the first and second steps to the outer surface of the concrete structure Wrapping the plurality of reinforcing plates may include welding the opposing reinforcing plates at the final end.

Here, the shape and structure of the connection part of the plurality of reinforcing plates is not limited, and may be configured in various embodiments such as a concave-convex structure. Also, the fixing pin connecting the connection parts of the plurality of reinforcing plates is not limited in its shape, connection function, or connection structure, and may be configured in various embodiments.

In addition, the material, shape, and structure of the support member for firmly fixing the opposite surfaces of both sides while maintaining the space between the underwater concrete structure and the reinforcing frame is not limited, and a hole ( For example, the support member may be fixed through an anchor hole). For example, the support member may be fixed by welding through holes in the plurality of reinforcing plates as a material of steel.

In addition, as another embodiment of the present invention, in the pouring step of the cross-section repair and reinforcement method, at least one opening and closing mortar inlet is provided on the plurality of reinforcing plates, and the mortar is delivered and injected from the land through the mortar inlet. can be characterized as

The present invention is to develop a mortar composition for underwater hardening with excellent adhesion between the wet and dry surfaces in repairing the underwater concrete structure, and apply it to the deteriorated area of the underwater concrete structure to provide a method of maintenance in the water. It is possible to extend the life of the entire underwater concrete structure by suppressing corrosion of the internal reinforcement of the concrete structure due to corrosion in the water and strengthening and reinforcing the destroyed part.

In addition, in the present invention, since the main material is composed of inorganic materials, the physical and chemical behavior is similar to that of the concrete structure to be repaired, thereby improving adhesion to the deteriorated repair site, and developing and mixing a super water-repellent adhesive material. It can facilitate underwater work and improve underwater workability.

In addition, the underwater hardening mortar composition of the present invention is composed of a composition quality with a high degree of hardening in water, adhesion between wet and dry surfaces in water, and strength after hardening. can be

In addition, the repair and reinforcement method of the underwater structure using the underwater hardening mortar of the present invention can provide repair convenience and quickness, thereby reducing the working time and increasing the safety of the operator.

1 is a flowchart illustrating a cross-sectional repair and reinforcement method of an underwater concrete structure according to an embodiment of the present invention.
2 to 7 are exemplary views illustrating the state of each step of FIG. 1 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them with reference to the accompanying drawings. However, the present invention may apply various transformations and may be embodied in various different forms, and is not limited to the embodiments described herein. That is, it should be understood that the present invention is not limited to specific embodiments and includes all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.

The components of the water-hardening mortar composition of the present invention include cements, super water-repellent curing agents, expansion materials, fillers, silica sand, fluidizing agents, reactivity modifiers, and stabilizers.

The specific composition ratio is 20 to 40 wt% of any one or more cements selected from the group consisting of general cement, slag cement, and Portland cement, and any one or more adhesives selected from the group consisting of epoxy, polyurethane, and acrylic urethane and particle diameters of 10 to 1000 Silica airgel of nanometer nanoparticles is dispersed in a weight ratio of 5:1 to 1:1, 5 to 20 wt% of a super water-repellent curing agent containing alkoxysilane and/or acetoxysilane, 3 to 15 wt% of an expansion material, 5 to 5 fillers 20 wt%, particle size adjustment silica sand 20 to 55 wt%, melamine-based, naphthalene-based, carboxyl-based fluidizing agent 0.2 to 1 wt% of any one selected from the group consisting of, 0.05 to 2 wt% of reactivity modifier, and calcium-based, barium-based, It includes 0.2 to 3 wt% of a stabilizer composed of at least one of zinc-based and magnesium-based stearate, but is not necessarily limited thereto.

Ordinary cement can be used as the main component, but it may be more preferable to use slag cement or sulfate-resistant cement. In particular, in the case of structures placed under marine environmental conditions, slag cement or sulfate-resistant cement with excellent resistance to sulfate erosion should be used. It exhibits excellent characteristics in durability to use.

On the other hand, Portland cement can be used in grades 1 to 5 depending on the application purpose.

The content of cement is composed of 20 to 40 wt% based on the total weight of the water-hardening mortar composition. If it is 30 wt% or less, the adhesion is reduced, and if it is 40 wt% or more, the dispersibility with other materials is lowered and the viscosity of the material is increased. Since there is a disadvantage in that the workability is reduced, an appropriate content ratio is selected according to the marine environment characteristics of the concrete structure to be repaired.

The super water-repellent curing agent of the water curing mortar is a nano-sized silica airgel having a particle diameter of 10 to 1000 nanometers dispersed in an adhesive such as an epoxy adhesive, a polyurethane adhesive, and an acrylic urethane adhesive in a weight ratio of 5:1 to 1:1. will be. In addition, alkoxysilane and/or acetoxysilane are added thereto.

The amount to be added of the alkoxysilane and/or acetoxysilane is not particularly limited, but may be 1 to 30 wt%, preferably 1 to 10 wt%, more preferably 5 to 10 wt%, based on the total weight of the super water-repellent curing agent. have.

The super water-repellent curing agent is a hydrophobic property that repels moisture, and it deteriorates while pushing out moisture during pouring and curing of the underwater hardening mortar during underwater repair work. The reinforcing mortar quickly hardens and attaches to the destroyed part.

In the work of the underwater repair and reinforcement method, the wet and dry surfaces of the part to be repaired must be quickly cured and firmly attached. It can be prepared by dispersing hydrophobic silica gel having a particle size (eg, aerosil R972, etc., EVONIK) in a weight ratio of 5:1 to 1:1.

The particle diameter of the silica airgel may be 10 to 1000 nanometers, more preferably 10 to 20 nanometers.

The super water-repellent curing agent disperses the adhesive and the silica airgel using an organic solvent, in which case the organic solvent is not particularly limited, but preferably high-purity propylene glycol mono-methyl ehter acetate (PGMEA), propylene glycol methyl ehter (PGME). , isopropyl alcohol, acetone, ethanol, etc. may be used.

At this time, in order to increase the dispersibility in the organic solvent, 0.5 to 3 wt% of an anionic or nonionic dispersant may be used based on the weight of the super water-repellent curing agent.

The addition of alkoxysilane and/or acetoxysilane to the super water-repellent curing agent is to further strengthen the adhesion in water by quickly and firmly bonding and condensing the wet and dry surfaces during the repair and reinforcement of the underwater structure.

In one embodiment of the present invention, the expansion material is calcium sulfo-aluminate (CSA), gypsum, calcium oxide (Ca0), calcium sulfate (CaSO ₄ ), alumina cement (Alumina cement), and calcium aluminate ( calcium aluminate) is selected from the group consisting of hydrates.

Particularly preferably, CSA (Calcium Sulfo-Aluminate) and gypsum or alumina cement can be used as the expansion material. CSA reacts with gypsum to generate ettringite to speed up the curing speed of the mortar and to increase the curing speed of the hardened body. It serves to prevent cracking and lifting.

When the content of the expansion material is less than 3wt%, the setting time in water of the mortar is delayed, so there is a risk that the injected mortar is diluted with water by the flow of water. Since it becomes difficult to secure the working time for injection, it is included at a level of 3 to 15 wt% based on the total weight of the mortar for water curing.

On the other hand, the filler of the water curing mortar of the present invention is _{fine silica powder, slag fine powder, fly ash fine powder, metakaolin fine powder, calcium carbonate (CaCO 3} ) and/or titanium dioxide (TiO ₂ ) From the group consisting of fine clay containing It may be selected, and preferably, it may include slag fines.

The filler is added to improve the mixing performance of the underwater hardening mortar, as well as to improve the durability and long-term strength of the hardening body.

_{Calcium carbonate (CaCO 3} ) or titanium dioxide (TiO ₂ ) may be included in the filler in an embodiment of the present invention, but in order to prevent carbonation or neutralization of the concrete structure in advance, it is not preferable that the filler is composed of only these materials, so slag The fine powder is used as the main ingredient and as an auxiliary ingredient.

In particular, the fine slag powder is ^{a latent hydraulic material as particles having a grain fineness of 5,000 g/cm 2 or more, and by reacting with Ca(OH) 2} generated during the hydration reaction of cement to produce calcium silicate hydrate, fine gaps in the hardened body are densely formed. It is used for the purpose of not only creating a hardened body with excellent durability, but also increasing resistance to acid.

If the filler containing slag fines is 5 wt% or less, resistance to acid or durability effect is reduced, and if it is 20 wt% or more, the compressive strength and surface hardness at the initial age are lowered, which has a disadvantage in that it adversely affects workability.

The mortar for water hardening of the present invention contains nano carbon material or boron nitride (BN) as an additional composition material for water hardening mortar in order to prevent the part where the concrete surface hardness is lowered when the slag fine filler is included in a high weight ratio. can do it

Nano carbon materials that can be additionally used to increase rigidity may be selected from among multi-wall carbon nanotubes, bundled carbon nanotubes, carbon nanoplates, plate-shaped graphite, graphene, and graphene oxide. Preferably, the multi-walled carbon nanotubes and the plate-shaped graphite are included in a ratio of 2:1.

The nano carbon material or boron nitride may be added in an amount of 0.01 to 3 wt% based on the total weight of the mortar for curing in water.

Nano carbon material is plate-shaped and has a maximized horizontal area, so it can perform excellently on water barrier properties and functions to prevent moisture movement. Therefore, it is possible to improve strength and workability when constructing the repair work of underwater concrete structures.

Among the nano-carbon materials, carbon nanotubes can be classified into single-walled, double-walled, and multi-walled carbon nanotubes according to the number of walls forming the tube shape. In one embodiment of the present invention, the carbon nanotubes used in the mortar composition are By using carbon nanotubes, the efficiency of the moisture shielding function can be increased.

In addition, since the moisture barrier and strength can be increased from the nano-carbon material that has expanded the horizontal area by using bundled carbon nanotubes or carbon nanoplates, even if the concrete structure elapses time after repair work, Corrosion can be strongly prevented.

As a preferred embodiment, the nano-carbon material may be composed of a multi-walled carbon nanotube as a main material, and a material selected from plate-shaped graphite, graphene, and graphene oxide is added as an auxiliary, and the content ratio may be 2:1. .

The diameter of the nano-carbon material may be 1 to 50 nm, preferably 1 to 30 nm. When the diameter exceeds 50 nm, there is a problem in that the formation efficiency of the composite particles with the polymer in the waterproof layer is reduced, and when the length of the nano-carbon material is increased, it is difficult to obtain a uniform particle size due to entanglement.

As a preferred embodiment, multi-walled carbon nanotubes, bundled carbon nanotubes, carbon nanoplates, plate-shaped graphite, and graphene nano-carbon materials are surface-treated to increase dispersibility when forming a composite with a polymer in a mortar for water curing. can

In the surface treatment of the nano-carbon material, a carboxyl value (-COOH), a hydroxyl group (-OH), or an epoxy group may be introduced to the surface of the nano-carbon material through treatment with an oxidizing agent or acid.

As the acid for the surface treatment, an aqueous inorganic acid solution selected from sulfuric acid, hydrochloric acid, and nitric acid may be used, and hydrogen peroxide may be used as the oxidizing agent.

In addition, ultrasonic waves may be used to improve the dispersibility of the nano-carbon material, and surface treatment using an acid or an oxidizing agent and ultrasonic treatment may be used in parallel.

In another embodiment of the present invention, the nano-carbon material used as a mortar composition for underwater hardening of concrete structures increases tensile strength by forming a composite with other composition materials, increases moisture barrier properties, and has long-term heat resistance. It is possible to maintain high stability of the repaired concrete structure after the repair work.

On the other hand, in the filler of the mortar for water hardening according to the present invention, the fine clay is bauxite, gibzite, diaspore, boehmite, amorphous hydrous alumina, limonite, quartz, feldspar, halloysite, kaolinite, nontronite, It may include minerals such as laterite, montmorillonite, and bentonite.

The fine clay will suffice as long as it contains a mineral that can be obtained from ordinary clay or kaolin rather than a rare mineral, but may preferably include bauxite, kaolinite, and the like.

The fine clay may have a particle size of several micrometers and a specific gravity of 0.5 to 2 within the weight of the filler material.

Minerals in fine clay can function to improve durability and adhesion strength by penetrating into the deteriorated pores of the underwater concrete structure and maintaining the concrete structure densely after repair treatment.

The mortar for water hardening of the present invention may contain 20 to 55 wt% of particle size-adjusted silica sand, and may be used by mixing 40 to 60 wt% of particle size No. 5 silica sand and 60 to 40 wt% of particle size No. 6 silica sand.

In the present invention, the fluidizing agent is added to improve the injectability when pouring the underwater hardening mortar during the concrete structure reinforcement construction, and melamine-based, naphthalene-based, and carboxyl-based fluidizing agents are used.

If the fluidizing agent is less than 0.2 wt%, the effect of improving the fluidity is weak, so a large amount of mixed water is used to cause a decrease in compressive strength. Because the content is limited.

The reactivity regulator of the mortar for water curing of the present invention is to secure an appropriate time for the injection operation by controlling the reaction rate of the mortar. It can be used in combination with one component or two to three components among retarders such as

If the reactivity modifier is less than 0.05wt%, it has no great effect on material separation and settling delay. If it exceeds 20wt%, the setting time of the mortar for water hardening becomes very slow, so material separation and excessive settling delay, etc. may cause the effect of

In addition, the stabilizer of the mortar for water hardening of the present invention can use calcium-based, barium-based, zinc-based, and magnesium-based stearate, and serves to prevent setting delay and strength decrease caused by water penetrating into the mortar do When the stabilizer is less than 0.2wt%, the effect of preventing the internal diffusion of water is insignificant, and when used in excess of 3wt%, the strength and adhesion of the mortar are greatly reduced.

As a specific embodiment of the present invention, a simple environment similar to the underwater environment is created by using the two versions of the underwater hardening mortar in the following component materials and composition ratios, and the same thickness is applied to the repair target part of a predetermined concrete block. The physical properties of the mixed mortar for repair of competitor A and the mixed mortar for repair of competitor B were compared, respectively.

(Composition ratio of mortar for water curing according to Specific Example 1 of the present invention)

28wt% of ordinary cement or slag cement;

12wt% of super water-repellent curing agent,

CSA inflatable 7wt%,

10wt% of slag fines;

40wt% of particle size adjustment silica sand,

glidant 0.5 wt%,

1 wt% of tartaric acid as a reactivity modifier;

1.5wt% of magnesium-based stearate as a stabilizer

(Composition ratio of mortar for water hardening according to Specific Example 2 of the present invention)

28wt% of ordinary cement or slag cement;

12wt% of super water-repellent curing agent,

CSA intumescent material 5wt%,

10wt% of slag fines;

1.45 wt% of nano carbon material containing multi-walled carbon nanotubes and plate-shaped graphite in a ratio of 2:1,

boron nitride 0.05 wt%;

0.5 wt% of anionic or nonionic dispersant;

40wt% of particle size adjustment silica sand,

glidant 0.5 wt%,

1 wt% of tartaric acid as a reactivity modifier;

1.5wt% of magnesium-based stearate as a stabilizer

For Examples 1 and 2 and Comparative Examples 1 and 2 of Competitor A and B, respectively, according to the present invention, the physical property values were adhesion strength, compressive strength, expansion rate, and setting time, and the concrete block under a simple environment similar to an underwater environment After injecting and curing the compositions of Examples and Comparative Examples to a thickness of 10 mm on the fracture surface, the age of the compositions was all 10 days, and the results are shown in the following table.

Test Items unit property value Example 1 of the present invention Example 2 of the present invention Comparative Example 1 (Company A) Comparative Example 2 (Company B) Adhesive strength kgf/cm ² 25 27 13 22 compressive strength kgf/cm ² 358 412 308 317 expansion rate % 0.02 0.02 0.05 0.03 Condensation Time (Second Condensation) hours: minutes 2:06 2:12 5:40 5:49 Condensation Time (Closed) hours: minutes 3:21 3:03 8:13 8:22

The difference between the composition and component ratio of Examples 1 and 2 is the same, but in Example 2, the content of the CSA expansion material was reduced and 1.5 wt% of a mixture of nano-carbon material and boron nitride was further added, and the dispersibility in the mortar was improved. It is characterized in that 0.5wt% of a dispersant was added to increase it. Referring to the results of the above table, the overall physical properties of Examples 1 and 2 were not significantly different, but the compressive strength of Example 2 was higher than that of Example 1. Since the final setting time is reduced compared to Example 1, it can be seen that the mortar properties in the repair work of the underwater concrete are better.

Overall, the water hardening mortars of Examples 1 and 2 according to the present invention have excellent effects in physical properties such as adhesion strength, compressive strength, expansion rate, and setting time compared to products A and B of other companies.

In particular, the initial setting time of Comparative Example 1 and Comparative Example 2 is 5 hours or more. If repair and reinforcement work is performed in water using cement or mortar with these characteristics, the ion concentration is diluted with water and the normal hydration reaction of the cement is performed. In addition to interfering with this, external water diffuses into the cement and expands the pores of the microtubule to form a porous structure. In addition, the moisture diffused into the cement reduces the material's viscosity, causing the reinforcing material to be desorbed before hardening, making it difficult to use it for underwater repair and reinforcement work.

In contrast, the underwater hardening mortars of Examples 1 and 2 according to the present invention have a relatively low expansion rate within the age of age, but have significantly higher adhesion and compressive strength than those of Comparative Examples, and the initial setting and termination processes are superior. Since it is done in a short time, it can quickly harden the base repair and reinforcement material during underwater work and shorten the construction period, so it can be expected to increase the safety of underwater workers.

Hereinafter, a method of repairing and reinforcing a concrete structure in the water according to another embodiment of the present invention will be described with reference to FIGS. 1 to 7 .

1 is a flowchart showing the repair and reinforcement method of the overall underwater concrete structure, and FIGS. 2 to 7 are exemplary views showing the state of each step of FIG. 1 .

The repair and reinforcement method shown in Fig. 1 consists of five steps: preparation step (S1), cradle installation and repair target site status measurement step (S2, S3), reinforcing frame production and installation step (S4), underwater hardening mortar pouring Steps (S5, S6), and a closing step (S7).

And the reinforcing frame installation step (S4) is specifically a first step of arranging a plurality of reinforcing plates spaced apart from the outer surface of the concrete structure by a predetermined distance and fixing the connecting portions of the reinforcing plates to each other with fixing pins, provided in the reinforcing plate A second step in which the support member connects the outer surface of the concrete structure and the plurality of reinforcing plates through a predetermined hole to maintain the separation distance, and repeating the first and second steps to remove the outer surface of the concrete structure Covering the surface with the plurality of reinforcing plates and welding the opposing reinforcing plates at the final end.

Hereinafter, each process will be described in detail.

When the repair and reinforcement target 30 is generated due to cracks, destruction, deterioration, etc. of the concrete structure 40 in the water and it is decided to start the repair work, the first underwater concrete structure 40 in the preparation step (S1) of FIG. ), after floating a barge (10) or a construction auxiliary ship around We are working on cleaning up the damaged parts.

A detailed exemplary diagram for this is shown in FIG. 2 . Referring to FIG. 2 , the contractor or worker 20 dives and performs the excavation work while turning the lowest bottom surface of the lower periphery of the underwater concrete structure 40 to flatten the periphery. This is a pre-preparation work to ensure that the facilities for the subsequent repair and reinforcement frame construction and the compensation work of the structural destruction part are stably installed. In addition, as shown in FIG. 2 , cleaning is performed by removing the dirty and deteriorated parts using high-pressure water for the part to be repaired 30 .

Next, the cradle installation step (S2) of FIG. 1 and the step (S3) of arranging the periphery of the concrete structure and accurately measuring the part to be repaired are performed.

These steps are specifically illustrated in FIG. 3 , and the cradle 50 is installed in the periphery of the underwater concrete structure 40 , and the workers 20 or divers watch the outer surface of the underwater concrete structure 40 , while the repair target part It is a process of accurately measuring or observing the number and shape of water bodies, the deteriorated state, the surrounding aquatic environment, and the degree of flow velocity.

Because the area to be repaired may be wide or narrow, or the area to be repaired may be narrow but the number of deteriorated parts may be quite large, accurate measurement of the area to be repaired is an important pre-work in implementing the repair and reinforcement method.

According to an embodiment, a mortar prepared with a mixing ratio of a special composition with enhanced adhesion between the wet and dry surfaces according to the deterioration area and state diagram of the part to be repaired may be custom-made and implemented.

Next, the fabrication and installation step S4 of the reinforcing frame of FIG. 1 is specifically illustrated in FIG. 4 . Referring to FIG. 4 , the reinforcing frame 60 is configured in a form in which a plurality of reinforcing plates are connected.

Specifically, an enlarged view of the shape of the reinforcing frame 60 is shown in FIG. 4 .

As can be seen with reference to FIG. 4 , a plurality of reinforcing plates are lowered into the water from the barge 10 and connected at a predetermined interval while surrounding the lower end of the concrete structure 40 in the water by the reinforcing plate connecting portion 602 . and installed

A plurality of reinforcing plates may be sequentially connected by arranging them spaced apart from the outer surface of the concrete structure by a predetermined distance and fixing the connecting portions 602 of the reinforcing plates to each other with fixing pins or the like. Since it is impossible to fix the concrete structure and the reinforcing plate with a predetermined separation space only by connecting a plurality of reinforcing plates, the support member is then connected to the outside of the concrete structure through a predetermined hole 603 provided in the reinforcing plate. The surface and the plurality of reinforcing plates are coupled to maintain the separation distance.

By repeating this process, a plurality of reinforcing plates surround the outer surface of the concrete structure while forming a predetermined space like a folding screen. Finally, the reinforcing frame 60 may be completed by welding the reinforcing plate facing the final end.

Figure 5 briefly shows that the reinforcement frame is finally installed around the underwater concrete structure to be repaired while connecting a plurality of reinforcing plates.

At this time, the shape and structure of the connection portion 602 of the plurality of reinforcing plates is not limited, and may be configured in various embodiments such as a concave-convex structure. Also, the fixing pin connecting the connection parts of the plurality of reinforcing plates is not limited in its shape, connection function, or connection structure, and may be configured in various embodiments.

In an embodiment, the fixing pin includes a transverse fastening part having an empty space in the transverse direction while connecting the connecting parts of the two reinforcing plates in the transverse direction, and a longitudinal direction that can penetrate the empty space of the transverse fastening part in a vertical direction. The fastening part may be in a combined form. That is, the fixing pin may be formed in a fastening structure forming a pair of male and female screw type or cross type for connecting the two connecting portions of the reinforcing plate and simultaneously fixing in the vertical direction once more.

In an embodiment of the present invention, a plurality of reinforcing frames 60 have been disclosed to be interconnected by a connection portion 602 of the reinforcing plate, but the present invention is not necessarily limited thereto. Of course, it can be connected.

On the other hand, the material, shape, and structure of the support member for firmly fixing the opposite surfaces of the two while maintaining the space between the underwater concrete structure and the reinforcing frame is not limited, and a plurality of reinforcing plates of the reinforcing frame 60 are The support member may be fixed through the formed hole (which may be, for example, an anchor hole) 603 . For example, the support member may be fixed by welding through holes in the plurality of reinforcing plates as a material of steel.

Also, as can be seen with reference to FIGS. 4 and 5 , the plurality of reinforcing plates may include at least one mortar inlet 601 , through which mortar for water hardening may be poured.

After the reinforcing frame 60 is formed around the underwater concrete periphery in the same manner as in FIG. 5 , mortar is poured through the mortar inlet 601 , and the mortar is placed between the outer surface of the concrete and the space A of the reinforcing frame 60 . is hardened into existence.

The height and width of the reinforcing frame 60 are not significantly limited, but may be high enough to cover the area to be repaired, or may be formed in a stacked structure for this purpose.

The reinforcing frame 60 is spaced apart from the outer circumferential surface of the concrete structure by a predetermined interval to prepare a space for pouring the underwater hardening mortar in the subsequent process, and at the same time to reduce the pressure generated after hardening of the underwater hardening mortar to be poured. plays a supporting role. Although the predetermined interval is not significantly limited, it is preferable to calculate and secure an appropriate separation distance in consideration of the safety, convenience, and speed of underwater work, and the curing speed and time in water of the underwater curing mortar. Preferably, there may be a separation distance of at least 15 to 20 cm.

The next water hardening mortar pouring step (S5) in the repair and reinforcement construction method of FIG. 1 is specifically illustrated in FIG. 6 .

6, the pouring step (S5) is a process of hardening by injecting the mortar for water hardening of the composition according to the present invention into the spaced space (A) between the reinforcing frame 60 and the concrete structure 40. . Specifically, at this time, the mortar for water curing may be prepared with the composition quality and component ratio of Example 1 or Example 2 according to the table above.

The mortar for water hardening is general cement or slag cement, super water-repellent curing agent, CSA expansion material, slag fine powder, (nano carbon material and boron nitride, dispersant), particle size adjustment silica sand, fluidizing agent, tartaric acid, Magnesium-based stearate is mixed and stirred and pumped for injection and pouring. At this time, it is injected through the mortar inlet 601 in the reinforcing plate of the reinforcing frame, which is configured to be opened and closed so that the hardening state is maintained by blocking the inlet immediately after injection.

In addition, additionally, as the last step of the repair and reinforcement method of FIG. 1 , the mortar for water hardening or cement for water hardening is additionally poured into the excavated part (B) of the periphery of the concrete structure 40 and hardened (S6). As shown in FIG. 6 , it is possible to serve as an underwater support of the concrete structure by additionally pouring and hardening the mortar or cement for underwater hardening in the dug portion of the lowermost base surface of the periphery of the concrete structure 40 .

According to the embodiment, in consideration of economic feasibility, it may be poured by injecting a known grout rather than using the mortar for water hardening of the present invention.

Finally, the periphery of the concrete structure after the repair and reinforcement method has been performed in step S7 is finished. 7 shows a state in which the mortar for underwater hardening is injected and hardened in the space between the reinforcement frame 60 and the outer surface of the structure by performing the repair and reinforcement method of the underwater concrete structure.

In the repair and reinforcement method of the underwater concrete structure of the present invention, when the mortar for water hardening according to the present invention is used, it is possible to work quickly, safely and economically due to the high speed of hardening in water, and the compressive strength and adhesion strength after hardening are excellent. It has the advantage of extending the life of the repaired underwater concrete structure.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

10 : barge
20: laborer
30: part to be repaired
40: underwater concrete structure
50: cradle
60: reinforcement frame
601: underwater mortar inlet 602: reinforcing plate connection part
603: Hall

Claims (10)

delete delete delete delete delete delete delete A preparation step of digging the underwater lowest periphery of the underwater concrete structure, and high-pressure washing of the repair target area;
Installing a cradle on the outer surface of the underwater concrete structure and measuring the condition of the part to be repaired;
A first step of disposing a plurality of reinforcing plates to be spaced apart from the outer surface of the underwater concrete structure by a predetermined distance and fixing the connecting portions of the reinforcing plates to each other with fixing pins;
A second step of maintaining the separation distance by coupling the support member with the outer surface of the underwater concrete structure and the plurality of reinforcing plates through a predetermined hole provided in the reinforcing plate;
repeating the first and second steps to install a reinforcing frame by wrapping the outer surface of the underwater concrete structure with the plurality of reinforcing plates and welding the opposing reinforcing plates at the final end;
into the space between the underwater concrete structure and the reinforcing frame.
20 to 40 wt% of any one or more cements selected from the group consisting of general cement, slag cement, and Portland cement, and any one or more adhesives selected from the group consisting of epoxy, polyurethane, and acrylic urethane and a particle diameter of 10 to 1000 nanometers The silica airgel of nanoparticles is dispersed in a weight ratio of 5:1 to 1:1, and 5 to 20 wt% of a super water-repellent curing agent containing alkoxysilane and/or acetoxysilane in an amount of 1 to 30 wt% based on the total weight of the super water-repellent curing agent, and an expansion material 3 to 15wt%, filler 5 to 20wt%, particle size adjustment silica sand 20 to 55wt%, melamine-based, naphthalene-based, carboxyl-based fluidizing agent 0.2 to 1wt%, reactivity modifier 0.05 to 2wt% A pouring step of filling the site to be repaired by injecting a mortar composition containing 0.2 to 3 wt% of a stabilizer consisting of any one or more of calcium-based, barium-based, zinc-based, and magnesium-based stearate; and
A cross-sectional repair and reinforcement method of an underwater concrete structure comprising a finishing step of filling and hardening the mortar in the excavation part of the periphery of the concrete structure in which the reinforcing frame is installed. delete 9. The method of claim 8,
The pouring step is
At least one opening and closing mortar inlet is provided in the plurality of reinforcing plates, and the cross-section repair and reinforcement method of an underwater concrete structure, characterized in that the mortar is delivered and injected from the land through the mortar inlet.

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