KR101931721B1 - Method for repairing concrete structure using eco-friendly inorganic polymer - Google Patents

Abstract

The present invention relates to a concrete structure repairing method using eco-friendly inorganic polymer of blast furnace slag and fly ash as a main material and using an alkali activator as a curing agent. According to the concrete structure repairing method, a concrete degradation portion of the concrete structure is removed; rust of reinforcing steel exposed from the concrete degradation portion is removed; repairing mortar is produced by stirring a mixture containing the blast furnace slag, the fly ash, zirconium silica fume, aggregates, the alkali activator, and water; and applying the repairing mortar to the concrete structure. The repairing mortar mixture contains 15-30 parts by weight of the zirconium silica fume with respect to 90-110 parts by weight of the blast furnace slag and 90-110 parts by weight of the fly ash to have 180 mm or more of slump flow of repairing mortar, maintained during a minimum of 40 minutes from a mixing point of the mixture, and to show 40 MPa or more of compression strength at 28 days of curing age. The present invention provides an excellent quality of repairing a concrete structure.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for repairing a concrete structure using an eco-friendly inorganic polymer,

Blast furnace slag, and fly ash as main materials and using an alkali activator as a curing agent.

As the industry develops, demand for concrete is increasing, for example, in the construction of structures and road construction. As the use of these concrete increases, the production of portland cement, which is the main component of concrete, is rapidly increasing. Such a cement industry is a representative industry for emitting a large amount of carbon dioxide together with the steel industry and the electric power industry. Such carbon dioxide is a type of greenhouse gas that is considered as a cause of global warming. Recently, in order to preserve the environment, various efforts have been made to reduce the generation of carbon dioxide worldwide, and the emission of greenhouse gases such as carbon dioxide It is in reality.

In particular, it is known that more than 0.8 tonnes of carbon dioxide is emitted to produce one ton of cement, which is the basis of concrete production. Accordingly, research for replacing cement with industrial byproducts such as blast furnace slag, fly ash, and the like is continuously being carried out. For example, a repair mortar has been developed in which blast furnace slag and fly ash are cured using an alkaline activator. In this way, the maintenance mortar using blast furnace slag and fly ash has the advantage of not only reducing carbon dioxide emissions but also having excellent chemical resistance. Cemented repair mortars are easily carbonated by carbon dioxide in the air and are easily corroded by sulfuric acid in acidic rock drainage from underground sewage structures and cut slopes, and are vulnerable to the proportional salts of coastal structures.

It takes at least 40 minutes to mix, stir, transport, pour, and finish the repair mortar. Accordingly, if the repair mortar loses its fluidity before 40 minutes, the repair work of the concrete structure becomes impossible or the maintenance quality of the concrete structure becomes very poor. However, the maintenance mortar using the blast furnace slag and the fly ash has the above merits. However, since the repair mortar caused by the alkali activator rapidly cures or the fluidity is lost due to the condensation, the maintenance work of the concrete structure is impossible, There is a problem that the maintenance quality becomes very poor.

Korean Patent No. 10-1366295 entitled " Powder type alkali activator for cement concrete, cement binder and cementless concrete using the same, " discloses a cement composition for cement concrete which can solve the problem of workability degradation due to the alkali activator Activation, cementless binder containing the same, and cement concrete containing the same. However, this conventional technique can not secure a slump flow of 180 mm required for mixing, stirring, transporting, casting, and finishing of the repair mortar for at least 40 minutes from the time of mixing, and the workability is very poor and the strength of the repair mortar is insufficient There is a problem.

Conventional concrete structure repair methods using cement repair mortar generally repair concrete structures by removing the deteriorated parts of concrete structures, removing rust of exposed reinforcing bars, and then applying cement repair mortar. As described above, the repair method using cementless maintenance mortar using only blast furnace slag and fly ash as an alternative agent for cement without using cement has a problem that the pH of the repair mortar hardened by blast furnace slag and fly ash is low, It has a problem of promoting corrosion rather.

Korean Patent No. 10-1472485 entitled " Geopolymer cement composition, mortar and method of using the same " refers to a method in which calcium oxide is used as a part of a material of a geopolymer cement composition so that the calcium oxide is reacted with water, However, when calcium oxide reacts with water, it shows a heat of about 100 degrees. This exothermic reaction not only threatens the safety of the workers manufacturing the mortar but also works poorly in mixing, transporting and pouring operations, resulting in deterioration of the maintenance quality. At high temperatures, as is well known, the alkali activator, blast furnace slag, fly ash There is a problem that the workability is drastically reduced due to the fact that the slump flow of 180 mm is maintained for at least 40 minutes because the reaction becomes active.

It uses at least 40 minutes of maintenance time for mixing mortar mixing, agitation, transportation, pouring, and plaster finish, while using blast furnace slag and fly ash as environmentally friendly inorganic polymer as main material and using alkali activator as hardening agent. And at the same time, the compressive strength of 28 days is more than 40 MPa, so that a concrete structure repairing method with excellent maintenance quality of concrete structure is provided. The present invention is not limited to the above-described technical problems, and another technical problem may be derived from the following description.

The method of repairing a concrete structure according to the present invention comprises the steps of removing a concrete deterioration part of a concrete structure; Removing rust of the exposed reinforcing bars from the concrete deteriorated portion; Preparing a repair mortar by stirring a mixture comprising blast furnace slag, fly ash, zirconium silica fume, aggregate, alkali activator, and water; And applying the prepared repair mortar to the concrete structure, wherein the slump flow of the repair mortar is maintained at least 40 minutes from the mixing point of the mixture at a slump flow of 180 mm or more, And 90 to 110 parts by weight of fly ash, 15 to 30 parts by weight of zirconium silica fume and 8 to 20 parts by weight of an alkali activator.

Wherein the mixture comprises 90 to 110 parts by weight of blast furnace slag, 90 to 110 parts by weight of fly ash, 15 to 30 parts by weight of zirconium silica fume, 8 to 20 parts by weight of an alkali activator, 250 to 350 parts by weight of aggregate, Section. The alkali activator is a non-aqueous form of Na ₂ SiO ₃ .nH ₂ O (n = 5, 6, 8, 9) free of H ₂ O and having a weight ratio of Na ₂ and SiO ₃ of 1: and a powder type of anhydrous sodium meta silicate (Na ₂ SiO ₃₎ may be used.

The mixture may further comprise 5 to 13 parts by weight of a pH adjusting agent. The pH adjuster may be a powder OPC of 6000 brain. The mixture may further comprise 5 to 20 parts by weight of limestone, 0.1 to 6 parts by weight of a fluidizing agent, 0.05 to 3 parts by weight of a shrinkage reducing agent, and fibers having a volume of 0.5 to 2% by volume based on the total volume of the repair mortar .

The method for repairing concrete structures according to the present invention comprises the steps of: applying a liquid film-hardening curing agent to the surface of a repair mortar applied to the concrete structure; And peeling the film-form curing agent from the surface of the repair mortar after the applied curing agent is cured in a film form.

The repair mortar used in the concrete structure repair method is prepared by stirring a mixture containing blast furnace slag, fly ash, zirconium silica fume, aggregate, alkali activator, and water, and the mixture is blended with 90 to 110 parts by weight of blast furnace slag, 15 to 30 parts by weight of zirconium silica fumarate and 8 to 20 parts by weight of an alkali activator are contained in an amount of 90 to 110 parts by weight based on 100 parts by weight of an ash-based inorganic polymer based on blast furnace slag and fly ash, The slump flow of the mortar is maintained at least 40 minutes from the mixing point of the mixture at 180 mm or more, so that the maintenance workability is excellent, and the compressive strength at 28 days is more than 40 MPa.

The mixture used in the production of the repair mortar is a mixture of 90 to 110 parts by weight of blast furnace slag, 90 to 110 parts by weight of fly ash, 15 to 30 parts by weight of zirconium silica fume, 8 to 20 parts by weight of alkali activator, 250 to 350 parts by weight of aggregate, And 30 to 50 parts by weight of water. The alkali activator comprises Na ₂ SiO ₃ .nH ₂ O (n = 5, 6, 8, 9) in a weight ratio of Na ₂ and SiO ₃ of 1: (H ₂ O) -free anhydrous form and powder type anhydrous sodium metasilicate (Na ₂ SiO ₃ ) is used to prevent the hardening of the repair mortar due to the alkali activating agent, thereby improving the mixing, stirring, transportation, pouring, The maintenance quality of the concrete structure is excellent as the compressive strength of the 28th day of the year exceeds 40MPa.

The mixture used in the preparation of the repair mortar further contains 5 to 13 parts by weight of a pH adjuster and the pH adjuster is a 6000 brain powder OPC so that the OPC contained in the maintenance mortar is almost completely hydrated during the curing period of 28 days The use of eco-friendly inorganic polymers such as blast furnace slag and fly ash is sufficient to produce enough calcium hydroxide in a short period of time to reduce the emission of greenhouse gases, which cause global warming, while greatly improving the neutralization resistance of the repair mortar. Occurrence can be prevented.

After the applied film curing type curing agent is applied to the surface of the reinforced mortar applied to the concrete structure and the applied curing agent is cured in the film form, the film type of curing agent is peeled off from the surface of the maintenance mortar, It is possible to protect the surface of the repair mortar from various weather phenomena and to prevent the foreign matter from penetrating the interface between the existing concrete structure and the repair mortar. In particular, chemical damage of the repair mortar caused by chlorine ion and sulfate ion can be prevented during the curing of the repair mortar applied to the coastal concrete structure.

1 is a flowchart of a method of repairing a concrete structure according to the present invention.
FIG. 2 is a photograph showing an actual construction of the curing system step 32 shown in FIG.
3 is a graph showing compression strengths of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention.
4 is a graph showing slump flows of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention.
5 is a graph showing compression strengths of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention.
6 is a graph showing slump flows of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention.
7 is a graph showing compressive strength and carbonation depth of Comparative Examples 14 to 16 of the present invention.
8 is a graph showing carbonation depths of Examples 9 to 12 and Comparative Examples 17 and 18 of the present invention.

The present invention relates to a method for repairing concrete structures using blast furnace slag and fly ash as environmentally friendly inorganic polymers as main materials and using an alkaline activator as a curing agent and more particularly to a method for repairing concrete structures using blast furnace slag and fly ash- As the hardening agent is used, the repair work time is required for at least 40 minutes for mixing, stirring, transporting, pouring, and finishing of the repair mortar. At the same time, the compressive strength of the 28 days of age exceeds 40 MPa, The present invention relates to a concrete structure repairing method having excellent maintenance quality. Hereinafter, this concrete structure repairing method will be briefly referred to as " concrete structure repairing method ".

The repair mortar used in the concrete structure repairing method according to the present invention is a mortar containing 90 to 110 parts by weight of blast furnace slag, 90 to 110 parts by weight of fly ash, 15 to 30 parts by weight of zirconium silica fume, 8 to 20 parts by weight of an alkali activator, 5 to 13 parts by weight of a pH adjusting agent, 5 to 20 parts by weight of limestone, 0.1 to 6 parts by weight of a fluidizing agent, 0.05 to 3 parts by weight of a shrinkage reducing agent, 30 to 50 parts by weight of water, Lt; RTI ID = 0.0 >% < / RTI > to 2% by volume. Since the fiber is very small in weight compared to other components and the specification of the weight portion is difficult, the content thereof is expressed as a volume ratio to the total volume of the repair mortar.

Among the components of the repair mortar, blast furnace slag, fly ash, zirconium silica fumarate, alkali activator, aggregate, pH adjuster, limestone, fluidizing agent and shrinkage reducing agent are in powder form before they chemically react to each other exist. Powder type blast-furnace slag and fly ash permeate between aggregates of various sizes, which is the main component of the repair mortar, and combine aggregates to serve as a binder to make the repair mortar into a single lump.

The blast furnace slag is mixed with the repair mortar to compensate the low initial strength of the repair mortar. When gypsum is added to the blast furnace slag, ettringite is produced. It is preferable that the blast furnace slag of the repair mortar used in the sewage pipe repairing method in which the sewage is to be flowed therein does not contain the gypsum because the ettringite is decomposed by binding with the hydrogen ion of the sulfuric acid generated in the sewage. The blast furnace slag preferably has a powder degree of 5000 to 7000 cm ² / g and a loss on ignition of 0 to 2%.

If the blast furnace slag has a powderity of less than 5000 cm ² / g, the particles become thick and reactivity with the activator becomes poor. When the blast furnace slag is more than 7000 cm ² / g, the viscosity of the repair mortar becomes excessively large. If the ignition loss exceeds 2%, excessive water is required and the strength of the repair mortar is lowered. The content of the blast furnace slag in the maintenance mortar is preferably 90 to 110 parts by weight. When the content of the blast furnace slag is less than 90 parts by weight, the strength of the repair mortar becomes low because the degree of hardening of the repair mortar is weak. When the blast furnace slag content exceeds 110 parts by weight, the reaction with the activator is excessively promoted, And the workability is deteriorated.

The fly ash preferably has a degree of powder of 3000 to 7000 cm ² / g and a loss on ignition of 0 to 2%. If the powdery degree of the fly ash is less than 3000 cm ² / g, the reactivity with the activator becomes thick due to the thick particles, and when the fly ash exceeds 7000 cm ² / g, the viscosity of the repair mortar becomes excessively large and the workability is deteriorated. If the ignition loss exceeds 2%, excessive water is required and the strength of the repair mortar is lowered. The content of fly ash in the maintenance mortar is preferably 90 to 110 parts by weight. When the content of the fly ash is less than 90 parts by weight, the components constituting the repair mortar are mixed, and the blast furnace slag reacts with the activator. As a result, the repair mortar hardens so rapidly that the components constituting the repair mortar are not uniformly mixed. If it exceeds, the strength is weakened at 28 days.

Zirconium silica fume improves the compressive strength of repair parts of concrete structures and densifies the structure, so that it has a high strength exceeding 40MPa compressive strength and a closed structure that does not cause cracks. Particularly, zirconium silica fume is used as a substitute material of silica fume generally used in maintenance mortar, thereby delaying the rapid curing time of the repair mortar caused by the alkali activating agent for a longer time. Thus, in order to secure the construction work time of the repair mortar, The flow is maintained at least forty minutes at 180 mm or more, and the compressive strength at the age of 7 days and at the age of 28 days is more than 40 MPa. The zirconium silica fume has a better slump loss than silica fume, but the slump loss can be further improved by using it in combination with the fluidizing agent.

The content of zirconium silica fume in the repair mortar is preferably 15 to 30 parts by weight. If the content of zirconium silica fumarate is less than 15 parts by weight, the strength of the repair mortar is not only insufficient, but also the workability of the repair mortar is short because of the short duration of the flowability of the repair mortar. If the content exceeds 30 parts by weight, Or even more, zirconium silica fume is an expensive material, and the manufacturing cost of the repair mortar becomes high, resulting in low economic efficiency.

Prior arts such as Korean Patent No. 10-1365664, No. 10-1375278, No. 10-1375279, "Super High Strength Concrete", etc., propose an ultra-high strength concrete capable of maximizing strength by applying zirconium silica fume and fibers have. However, this prior art does not use eco-friendly inorganic polymer such as blast furnace slag, fly ash, etc., and is related to cement concrete mainly made of cement. In order to secure the repair work time of concrete structure, the slump flow of the repair mortar is 180 mm or more It is not used to keep it for at least 40 minutes. As a result, the composition ratio between the components of the repair mortar of the present invention and the prior art concrete composition is completely different.

Alkali activator reacts with inorganic polymer such as blast furnace slag, fly ash and so on to harden the repair mortar. Activator is a slump flow of the repair mortar is held at least 40 minutes at least 180mm and the weight ratio of Na ₂ and SiO ₃ to more than 40 MPa compressive strength can be expressed, 1 is the composition as a 0.5 ~ ₂ Na 2 SiO ₃ and nH ₂ O (n = 5, 6, 8, 9) H ₂ O-free anhydrous form powdered anhydrous sodium metasilicate (Na ₂ SiO ₃ ) is used. The content of the alkaline activator in the maintenance mortar is preferably 8 to 20 parts by weight. If the content of the alkali activating agent is less than 8 parts by weight, the hardening of the repair mortar may not be sufficiently cured and the strength of the repair mortar may be lowered. If the amount of the alkaline activating agent is more than 20 parts by weight, the hardening reaction of the repair mortar proceeds too quickly, In addition, the alkaline activator is costly because it is expensive and the manufacturing cost of the repair mortar is high.

The aggregate is used as the main component of the repair mortar, No. 7 silica (SiO ₂ = 95%, density = 2.62 g / cm 3). The amount of the aggregate in the repair mortar is preferably 250 to 350 parts by weight. When the content of the fine aggregate is less than 250 parts by weight, water is excessively required as the viscosity of the repair mortar increases, and the shrinkage increases during the drying process of the repair mortar, so that cracks may occur in the repair mortar. The compressive strength is lowered and the surface of the repair mortar becomes rough.

The pH adjuster serves to prevent rebar corrosion inside the hardened repair mortar. As the pH adjusting agent, powdered OPC (Ordinary Portland Cement) of 6000 brain is used. When mixed with water, OPC generates calcium hydroxide (Ca (OH) ₂ ) as a hydrate. The pH of the cured preservative mortar is elevated to 12 or higher to form a passive coating on the reinforcing bars in the repair mortar, Prevent corrosion. Fly ash and blast furnace slag accelerate neutralization, that is, carbonation in an environment with a pH of 11 or less. The content of the pH adjuster in the maintenance mortar is preferably 5 to 13 parts by weight. When the content of the pH adjusting agent is less than 5 parts by weight, the neutralization of the repair mortar rapidly proceeds, and the probability of rusting of the reinforcing bar is very high. When the amount of the pH adjusting agent is more than 13 parts by weight, the content of other admixture decreases, There is a risk of shortening.

Limestone not only improves the initial strength of the repair mortar but also reduces the unit yield and bleeding. Limestone is a limestone fine powder having calcium oxide (CaO) of 90% or more, a powder viscosity of 5000 brains or more, and an average particle size of about 20 탆. When the repair mortar is cured due to blast furnace slag and fly ash, unreacted latence due to bleeding remains on the surface. The limestone fine powder increases the flow path of water rising by the bleeding phenomenon, thereby physically reducing the bleeding and reducing the unit yield, thereby effectively acting on the initial strength enhancement. The content of limestone in the repair mortar is preferably 5 to 20 parts by weight. If the content of limestone is less than 5 parts by weight, the initial strength of the repair mortar is weak and the unit yield and bleeding decrease are insufficient. When the amount is more than 20 parts by weight, the strength of the repair mortar is lowered.

The fluidizing agent serves to improve the durability and workability of the repair mortar by dispersing the powder particles of the repair mortar. As the fluidizing agent, a high-performance water reducing agent having a dispersing effect higher than that of a general water reducing agent is suitably used as a fluidized naphthalene type, organic acid type, melamine type, and polycarboxylic type. As the fluidizing agent, a high-performance water reducing agent in the form of a dark brown powder having a polycarboxylic acid-based density of 1.05 g / cm ³ and a specific gravity of 2.05 ± 0.05 at 20 ° C. is used. The content of the fluidizing agent in the repair mortar is preferably 0.1 to 6 parts by weight. If the content of the fluidizing agent is less than 0.1 parts by weight, the effect of reducing water hardly occurs. If the amount of the fluidizing agent is more than 6 parts by weight, separation of components having different specific gravity occurs.

The shrinkage reducing agent acts as a nonionic surface activating agent to reduce the surface tension in the capillary of the repair mortar to prevent drying shrinkage. Generally, shrinkage reducing agent and Awun-type swelling agent are used simultaneously to reduce shrinkage of maintenance mortar, but since Awun-type swelling agent causes expansion by sulfuric acid, it is not used for repair mortar for sewage pipe maintenance purpose. The content of the shrinkage reducing agent in the maintenance mortar is preferably 0.05 to 3 parts by weight. If the content of the shrinkage reducing agent is less than 0.05 part by weight, the shrinkage may increase during the drying process of the repair mortar to cause cracking in the repair mortar. If the shrinkage reducing agent is more expensive than 3 parts by weight, the manufacturing cost of the repair mortar becomes higher It is not economical.

It is preferable that water does not contain oil, acid, salts, organic matter and other harmful substances, and it controls the workability and strength of the whole repair mortar according to its content. The content of water in the maintenance mortar is preferably 30 to 50 parts by weight. When the content of water is less than 30 parts by weight, the water content of the repair mortar is insufficient as a whole, and workability is deteriorated. When the amount of water is more than 50 parts by weight, cracks are generated in the course of curing the repair mortar.

The fibers serve to prevent shrinkage cracking during the curing process of the repair mortar. The fibers may be selected from acrylic, nylon, polyvinyl alcohol, polypropylene, carbon fibers, and reinforced staple fibers of aramid. The fibers are hydrophilic polyvinyl alcohol reinforcing staple fibers having a thickness of 10 to 20 μm and a length of 4 to 8 mm or less. The volume fraction of fibers in the repair mortar preferably accounts for 0.5 to 2% by volume of the total volume of the repair mortar. If the volume percentage of the fibers is less than 0.2%, there is no effect of preventing the crack as described above. If the volume percentage of the fibers is more than 2%, bundles of fibers are formed in the repair mortar and the strength of the repair mortar is lowered.

1 is a flowchart of a method of repairing a concrete structure according to the present invention. Referring to FIG. 1, the concrete structure repairing method according to the present invention includes the following steps. In the deterioration site removal step (11), the concrete deterioration part is removed from the concrete structure by cutting the deterioration part of the concrete of the concrete structure to be repaired. For example, it is possible to cut concrete deterioration areas of concrete structures by injecting high-pressure water into concrete deterioration areas of concrete structures. Thus, when the deteriorated portion of the concrete is cut from the concrete structure, the reinforced concrete buried in the deteriorated portion of the concrete is exposed. In the reinforcing steel rust removing step (12), the rust of the reinforcing bar exposed from the concrete structure is removed by removing the deteriorated portion of the concrete in the deteriorating portion removing step (11).

In the rust preventive application step (13), the rust inhibitor is applied to the reinforcing bar from which the rust is removed in the reinforcing bar rust removal step (12). It is preferable to apply an organic or inorganic alkali rust inhibitor having a pH of 12 or more and containing zinc in the reinforcing bar. Applying such an anticorrosive agent having a pH of 12 or more to the reinforcing bars may form a passive film on the reinforcing bars to prevent corrosion of the reinforcing bars and to prevent contact between the reinforcing bars and harmful materials. Also, since the galvanic effect of the end of the year can prevent the corrosion of the steel reinforcing bars, the corrosion of the steel reinforcing bars can be prevented. In the adhesive applying step (14), new and old concrete adhesives are applied to the removed surface of the concrete deterioration area. Epoxy resin and polyester resin adhesives are mainly used for bonding joints of new and old concrete.

In the mixing and stirring step 20, a mixture composed of blast furnace slag, fly ash, zirconium silica fumarate, alkali activator, aggregate, pH adjuster, limestone, fluidizing agent, shrinkage reducing agent, water and fibers is homogenized by stirring, . The mixture of blast furnace slag, fly ash, zirconium silica fume, alkali activator, aggregate, pH adjuster, limestone, fluidizing agent, shrinkage reducing agent, water and fibers is homogenized by being introduced into the mixer and stirred for about 3-5 minutes . The mixture in the mixer may be automatically stirred by a propeller or the like rotated by a motor or the like, or may be manually stirred by an operator.

In the mixing and stirring step 20, 90 to 110 parts by weight of blast furnace slag, 90 to 110 parts by weight of fly ash, 15 to 30 parts by weight of zirconium silica fume, 8 to 20 parts by weight of an alkali activator, 250 to 350 parts by weight of aggregate, 5 to 13 parts by weight of limestone, 0.1 to 6 parts by weight of a fluidizing agent, 0.05 to 3 parts by weight of a shrinkage reducing agent, 30 to 50 parts by weight of water and 0.5 to 2% The bulked fibers are put into a mixer and mixed and stirred to prepare a repair mortar.

In the mortar applying step 31, the maintenance mortar manufactured in the mixing and stirring step 20 is applied to the adhesive application side of the concrete structure in which the adhesive application in the adhesive application step 14 is completed. In the curing system imparting step (32), the liquid film curing type curing agent is applied to the surface of the repair mortar of the concrete structure completed with the maintenance mortar in the mortar applying step (31). A liquid styrene-butadiene rubber may be used as the material of the liquid film curing type curing agent. In the curing system step (32), a liquid film-hardening curing agent is applied to the surface of the hardening mortar which has not yet been cured.

In the curing agent stripping step (33), the curing agent applied in the curing system step (32) is cured in the form of a film, and then the cured film form of curing agent is peeled off from the surface of the retentive mortar. In the surface coating application step 34, the chemical resistant surface coating is applied on the surface of the repair mortar exposed by the curing agent exfoliation in the curing agent stripping step (33). Here, the chemical resistant surface coating agent is preferably a water-soluble epoxy or a water-soluble ceramic based surface coating agent, but other general-purpose products may be used.

 In the early stage of the curing process, the surface of the repair mortar is removed from the weather phenomenon such as direct sunlight, rain, wind, frost, etc., since the hardening mortar is first applied to the concrete structure and then condensation starts by the hydration reaction. Curing is required to protect the surface of the repair mortar in order to protect the mortar, maintain the humidity suitable for curing of the repair mortar, minimize drying shrinkage of the repair mortar and prevent cracking. Such curing can be classified into wet curing which sprays water on the surface of the repair mortar, curing curing which covers the surface of the repair mortar with a film of vinyl, cloth or the like, and coating curing which sprayes the curing agent on the surface of the repair mortar .

In the case of repairing concrete structures, most of the cases where only the deteriorated part is removed from the top, bottom, and sides of the concrete structure and the repair mortar is applied. Since the area also varies from 0.1 ㎡ to several ㎡, It is practically impossible to carry out curing to protect the surface of the repair concrete. In the case of repairing offshore facilities, it takes several days for the repair mortar to harden and develop its strength. During the initial hardening period, when the repair mortar is immersed in seawater or exposed to flying salt, The reinforcing bars inside the repair mortar are damaged.

Generally, in a concrete structure, deterioration sites occur not only in various places, but also on irregularities on various surfaces such as top, bottom, and side surfaces. Therefore, wet curing may occur irregularly It is difficult to supply the water to the deteriorated part, and the wet curing has a problem that it is difficult to fix the membrane to the upper surface and the side surface of the concrete structure, and even if the membrane is fixed, it sticks to the surface of the repair mortar to damage the surface of the repair mortar. The oily curing agent roots on the surface of the repair mortar are emerging as an alternative. However, after the curing of the repair mortar, the surface coating agent is generally applied, and the coating curing has a problem that the residual component of the oily curing agent is likely to lower the adhesion force between the surface coating agent and the repair mortar.

FIG. 2 is a photograph showing an actual construction of the curing system step 32 shown in FIG. 2 (a) is a photograph showing a worker applying a liquid film-curing type curing agent on a surface of a repair concrete in a liquid state. Fig. 2 (b) is a photograph showing a state where the operator has completed the application of the liquid film-curing curing agent. FIG. 2 (c) is a photograph of a worker peeling a cured curing agent in a film form. 2 (d) is a photograph showing the latency attached to the curing agent film peeled from the surface of the repair mortar. FIG. 2 (e) is a photograph showing a latent image of a white thin film formed on the surface of the repair mortar after the curing of the repair mortar in the state that the liquid film curing type curing agent is not applied. Fig. 2 (f) is a photograph of the appearance of such latency appearing on the operator's hand.

The liquid film curing type curing agent is cured in a film form after 2 to 3 hours from the time when the liquid curing agent is applied on the surface of the repair mortar. The curing agent in the form of a film adheres to the surface of the repair mortar, and when the strength of the repair mortar is manifested above a certain level, the worker peels off the surface of the repair mortar. The application of the liquid film curing type curing agent to the surface of the maintenance mortar not only prevents moisture evaporation from the surface of the maintenance mortar but also protects the surface of the maintenance mortar from various weather effects and protects the surface of the existing concrete structure and the repair mortar Can block this penetration. In particular, chemical damage of the repair mortar caused by chlorine ion and sulfate ion can be prevented during the curing of the repair mortar applied to the coastal concrete structure.

As shown in Figs. 2 (e) and 2 (f), on the surface of the repair mortar containing blast furnace slag or fly ash, a latence layer made of unreacted material is formed by bleeding, The alkali component of the activator is exposed to the surface of the repair mortar. This latency is a cause of deteriorating the adhesion of the surface coating agent in the step of coating the surface coating, which is the final stage of the concrete structure repairing method. Therefore, it is inconvenient for the operator to remove the lattens formed on the surface of the repair mortar in order to realize the adhesive force of the surface coating agent as it is in the original performance of the surface coating agent product. According to the present invention, in the process of peeling the liquid film curing type curing agent from the surface of the repair mortar, latency is adhered to the surface of the curing agent in the film form, thereby enhancing the adhesion of the surface coating agent to the surface of the maintenance mortar.

The concrete structure repairing method according to the present invention can be more specifically understood by the following examples and comparative examples, and the following examples are merely examples for illustrating the present invention, It does not. Examples 1 to 4 and Comparative Examples 1 to 7 of the repair mortar of the present invention were prepared as follows to evaluate the workability and strength of the repair part of the concrete structure repair method according to the present invention. In particular, Examples 1 to 4 and Comparative Examples 1 to 7 are examples for evaluating the maintenance workability and the strength change of the repair portion according to the content of zirconium silica fume or the content thereof. Examples 1 to 4 of the repair mortar of the present invention were prepared with compositions and composition ratios as shown in Table 1 below.

unit division Example 1 Example 2 Example 3 Example 4



Powder (parts by weight) Blast furnace slag 100 100 100 100 Fly ash 100 100 100 100 Z-silica fume 15 20 25 30 Activator 14 14 14 14 aggregate 300 300 300 300 pH adjuster 9 9 9 9 Limestone 12 12 12 12 Fluidizing agent 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3

≪ Examples 1 to 4 >

As shown in Table 1, in Example 1 of the present invention, 100 parts by weight of blast furnace slag, 100 parts by weight of fly ash, 15 parts by weight of zirconium silica fume, 14 parts by weight of an alkali activator, 300 parts by weight of aggregate, 12 parts by weight of limestone, 3 parts by weight of fluidizing agent, 1.2 parts by weight of shrinkage reducing agent, 40 parts by weight of water and fibers having a volume of 1.3% based on the total volume of the repair mortar were mixed to prepare a repair mortar. In Examples 2 to 4 of the present invention, other components other than zirconium silica fume were mixed at the same composition ratios as those of Example 1 and different parts by weight of zirconium silica fume at 20, 25, and 30, respectively.

In Examples 1 to 4 of the present invention, powder of anhydrous sodium metasilicate having a weight ratio of Na ₂ and SiO ₃ of 1: 1 was used as the alkali activator, silica sand No. 7 was used as an aggregate, and 6000 brains Of powder type OPC was used as the limestone, powder type limestone of 5000 brain was used, the powder type naphthalene type water reducing agent was used as the fluidizing agent, the powder type nonionic surface activating agent was used as the shrinkage reducing agent, Vinyl alcohol reinforcing staple fibers were used. The repair mortars of Examples 1 to 4 were prepared with other manufacturing conditions and environments that could affect the performance of the repair mortar to be almost the same. For example, the mixture agitation inside the mixer proceeded for approximately three minutes for all of Examples 1-4.

Comparative Examples 1 to 3 of Examples 1 to 4 of the present invention were prepared with compositions and composition ratios as shown in Table 2 below.

unit division Comparative Example 1 Comparative Example 2 Comparative Example 3



Powder (parts by weight) Blast furnace slag 100 100 100 Fly ash 100 100 100 Silica fume 0 15 30 Activator 14 14 14 aggregate 300 300 300 pH adjuster 9 9 9 Limestone 12 12 12 Fluidizing agent 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3

≪ Comparative Examples 1 to 3 >

As shown in Table 2, in Comparative Example 1 of Examples 1 to 4 of the present invention, zirconium silica fume was not added to the mixer, and other components except for this were mixed in the same composition ratio as in Example 1. In Comparative Example 2-3, silica fume was added in place of zirconium silica fume, and the other components except for the silica fume were mixed in the same composition ratio as in Example 1. Particularly, in Comparative Example 2, the weight of the silica fume was set to 15, and in Comparative Example 3, the weight of the silica fume was set to 30. And other manufacturing conditions and environments that may affect the performance of the repair mortar were set to be substantially the same as Example 1 of the present invention, and the repair mortars of Comparative Examples 1 to 3 were produced.

Comparative Examples 4 to 7 for Examples 1 to 4 of the present invention were prepared with compositions and composition ratios as shown in Table 3 below.

unit division Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7



Powder (parts by weight) Blast furnace slag 100 100 100 100 Fly ash 100 100 100 100 Z-silica fume 5 10 35 40 Activator 14 14 14 14 aggregate 300 300 300 300 pH adjuster 9 9 9 9 Limestone 12 12 12 12 Fluidizing agent 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3

≪ Comparative Examples 4 to 7 >

As shown in Table 2, in Comparative Examples 4 to 7 of Examples 1 to 4 of the present invention, the other components except zirconium silica fume were the same as those of Example 1, and the weight parts of zirconium silica fume were 5 , 10, 35, and 40, respectively. Other repairing conditions and environments that could affect the performance of the repair mortar were prepared in the same manner as in Example 1 of the present invention, and the repair mortars of Comparative Examples 4 to 7 were produced.

≪ Test Example 1 >

Two specimens were prepared for each of the repair mortars of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention in accordance with the Korean National Standard KS F 2405 "Method for Testing Compressive Strength of Concrete", and a total of 11 pairs of specimens The compressive strength test was carried out as follows. The specimens of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention were cured under the same conditions as those of the concrete structure repair method according to the present invention, For each of the 11 specimens selected from 1 to 7, the compressive strength of each specimen was measured with a compression tester of KS B 5533 at 7 days of age and the remaining 11 specimens were measured for compressive strength Were measured. The test results are shown in Fig.

3 is a graph showing compression strengths of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention. The performance standard of the compressive strength of high strength concrete structures specified by the Government of the Republic of Korea is over 40MPa. Accordingly, in the embodiment of the present invention, the target compressive strength is 40 MPa. Referring to FIG. 3, it can be seen that the compressive strengths of all of Examples 1 to 4 of the present invention exceeded the target compressive strength of 40 MPa in all of "ZSF = 15, 20, 25, 30" at 7 days and 28 days. In particular, when the lower limit of 15 parts by weight and the upper limit of 30 parts by weight of the zirconium silica fume content of the present invention were used, the compressive strengths at 28 days were about 49 MPa and 56 MPa, respectively. Compared to the compressive strength of 32 MPa of Comparative Example 1, And 54% ~ 76%, respectively.

In Comparative Example 1 "SF = 0" in which no silica fume or zirconium silica fume was used, all the compressive strengths at the ages of 7 days and 28 days were far below the target compressive strength of 40 MPa. It can be seen that the compressive strength of Comparative Example 2 " SF = 15 " using silica fume instead of zirconium silica fume and Comparative Example 3 " SF = 30 " exceeds the target compressive strength of 40 MPa. However, in Comparative Example 2, the initial compressive strength at the age of 7 days is less than the target compressive strength of 40 MPa.

COMPARATIVE EXAMPLE 4 It can be seen that the compressive strength at the age of 28 days at "ZSF = 5" is less than the target compressive strength of 40 MPa. COMPARATIVE EXAMPLES 5 TO 7 It can be seen that the compressive strength at 28 days of age at the time of "ZSF = 10, 35, 40" exceeds the target compressive strength of 40 MPa at 28 days of age. When the content of zirconium silica fume is less than 15 parts by weight, the strength of the repair mortar is insufficient in comparison with the target compressive strength. When the content of zirconium silica fume exceeds 30 parts by weight, the rate of increase in the strength of the repair mortar is insufficient It can be seen that it is further decreased. If the content of zirconium silica fume in the repair mortar is excessively large, it is interpreted that the strength of the repair mortar is lowered as the content ratio of other components contributing to the strength of the repair mortar, for example, the alkali activator is decreased.

Particularly, in all of Comparative Examples 1 to 7, the initial compressive strength at the age of 7 days is less than the target compressive strength of 40 MPa. Repair of a concrete structure is generally carried out while the use of the concrete structure is suspended, but a concrete structure is often used even during a period in which the concrete structure is inevitably repaired such as a bridge. Therefore, in the repair method of concrete structure, it is very important that the initial strength before the hardening of the repair mortar is completely different from the construction method of the concrete structure. According to the present invention, even if the concrete structure is used during the repair period of the concrete structure, the probability of occurrence of the accident due to the damage of the repair portion of the concrete structure is increased as the initial strength of the 7 days of the repair portion of the concrete structure exceeds the target compressive strength of 40 MPa There are few.

≪ Test Example 2 &

According to Korean National Standard KS F 2476 " Test Method of Polymer Cement Mortar ", the flowability test for each of the repair mortars of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention was carried out as follows. The repair mortar of each of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention was filled into 22 slump cones, two of each of which were prepared according to each of the examples and the comparative examples, and evenly sintered.

After 10 minutes from the mixing time of the mixture in the mixer in the mixing and stirring step 20, 11 slumps were selected from 22 slump cones according to Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention, The cone was dropped 15 times for 15 seconds on the flow table. At this time, the length in the vertical direction was measured in the state where the repair mortar was spreading at the maximum, and the average value thereof was measured by the slump flow.

For the remaining 11 slump cones, the mixture was put into the mixer in the mixing and stirring step (20), and after 40 minutes passed from the mixing point, the dropping motion was performed 15 times for 15 seconds on the flow table. At this time, the length in the vertical direction was measured in the state where the repair mortar was spreading at the maximum, and the average value thereof was measured by the slump flow. The test results are shown in Fig. The concrete structure repairing method of the present invention requires at least 40 minutes from the mixing point of the mixture in the mixing and stirring step (20) to the mixing mortar mixing, stirring, transportation, pouring, and finishing finish do. Accordingly, in this test, the slump flow was measured twice at 10 minutes and 40 minutes after mixing.

4 is a graph showing slump flows of Examples 1 to 4 and Comparative Examples 1 to 7 of the present invention. The higher the fluidity of the repair mortar, that is, the longer the slump flow of the repair mortar is measured, the better the workability but the compressive strength of the repair site of the concrete structure is lowered. For this reason, the Architectural Engineering Standard Specification Specification and various specifications of the Japanese Construction Engineering Society suggest that the slump flow should be less than 180mm as a criterion that can satisfy both workability and compressive strength at the same time. In the embodiment of the present invention, the target slump flow is 180 mm.

Referring to FIG. 4, it can be seen that Examples 1 to 4 of the present invention, "ZSF = 15, 20, 25, 30" all have a slump flow of 10 minutes and 40 minutes after mixing exceeding a target slump flow of 180 mm. Particularly, the slump flow of 10 minutes and 40 minutes after mixing in the case of using the lower limit of 15 parts by weight and the upper limit of 30 parts by weight of the zirconium silicalum fume content of the present invention was 196 mm and 202 mm respectively, and the slump flow 171 of Comparative Example 1 mm and the workability is improved by 14 ~ 18%.

In Comparative Example 1 " SF = 0 " in which no silica fume or zirconium silica fume was used, it can be seen that both the slump flow of 10 minutes and 40 minutes after mixing did not reach the target slump flow of 180 mm. The slump flow of Comparative Example 2 " SF = 15 " using silica fume instead of zirconium silica fume and 10 minutes of mixing after " SF = 30 " of Comparative Example 3 exceeded the target slump flow of 180 mm but the slump flow of 40 minutes, It can be seen that it does not reach the flow. As described above, the slump flow of 40 minutes in Comparative Examples 1 to 3 in which silica fume or zirconium silica fume was not used or the silica fume in Comparative Examples 1 to 3 did not satisfy the target slump flow, so that the repair mortar hardened during the repair of the concrete structure, The castle is very poor.

It can be seen that the slump flow of 10 minutes after mixing at the comparative example 4, 5 "ZSF = 5, 10" exceeds the target slump flow of 180 mm but the slump flow of 40 minutes fails to reach the target slump flow. In Comparative Example 6, 7 "ZSF = 35, 40", the slump flow of 10 minutes and 40 minutes after mixing exceeds the target slump flow of 180 mm. From these test results, if the content of zirconium silica fumarate is less than 15 parts by weight, the maintenance time of the repair mortar is short and the workability is very poor. When the amount exceeds 30 parts by weight, expensive zirconium silica fume And the economical efficiency is lowered.

Examples 4 to 8 and comparative examples 8 to 13 of the repair mortar of the present invention were prepared as follows to evaluate the workability and strength of the repair part of the concrete structure repair method according to the present invention. In particular, Examples 4 to 8 and Comparative Examples 8 to 13 are examples for evaluating the change of the material of the alkali activator and the change of the repair workability and the repair portion strength according to the content. Examples 4 to 8 of the repair mortar of the present invention were prepared with composition and composition ratio as shown in Table 4 below.

unit division Example 5 Example 6 Example 7 Example 8



Powder (parts by weight) Blast furnace slag 100 100 100 100 Fly ash 100 100 100 100 Z-silica fume 20 20 20 20 Anhydrous activator 8 12 16 20 aggregate 300 300 300 300 pH adjuster 9 9 9 9 Limestone 12 12 12 12 Fluidizing agent 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3

≪ Examples 5 to 8 >

As shown in Table 4, in Example 5 of the present invention, 100 parts by weight of blast furnace slag, 100 parts by weight of fly ash, 20 parts by weight of zirconium silica fume, 8 parts by weight of an alkali activator, 300 parts by weight of aggregate, 12 parts by weight of limestone, 3 parts by weight of fluidizing agent, 1.2 parts by weight of shrinkage reducing agent, 40 parts by weight of water and fibers having a volume of 1.3% based on the total volume of the repair mortar were mixed to prepare a repair mortar. In Examples 6 to 8 of the present invention, other components other than the alkaline activator were mixed in the same proportions as in Example 5, and the weight of the alkaline activator was changed to 12, 16, and 20, respectively.

All the components of Examples 5 to 8 of the present invention were the same as all the components of Example 1 described above. For example, the alkali activator is the weight ratio of Na ₂ SiO ₃ and 1: The composition is a 0.5 ~ ₂ Na 2 SiO ₃ and nH ₂ O-free H ₂ O of (n = 5, 6, 8,9 ) the anhydrate form of a powder type of anhydrous sodium metasilicate (Na ₂ SiO ₃₎ was used. Similar to the above-described Examples 1 to 4, the repair mortars of Examples 5 to 8 were prepared with other manufacturing conditions and environments that could affect the performance of the repair mortar set almost the same.

Comparative Examples 8 and 9 for Examples 5 to 8 of the present invention were prepared with compositions and composition ratios as shown in Table 5 below.

unit division Comparative Example 8 Comparative Example 9



Powder or liquid phase
(Parts by weight) Blast furnace slag 100 100 Fly ash 100 100 Z-silica fume 20 20 Activator 8 (liquid phase) 8 (5H ₂ O) aggregate 300 300 pH adjuster 9 9 Limestone 12 12 Fluidizing agent 3 3 Shrinkage abatement agent 1.2 1.2 Liquid phase (parts by weight) water 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3

≪ Comparative Examples 8 and 9 >

As shown in Table 5, in Comparative Example 8 of Examples 5 to 8 of the present invention, the weight ratio of Na ₂ and SiO ₃ was changed to the ratio of Na ₂ and SiO ₃ in place of powdery anhydrous sodium metasilicate having a weight ratio of Na ₂ and SiO ₃ of 1: 1: 1 liquid anhydrous sodium metasilicate was used, and the other components were mixed at the same composition ratio as the same composition of Example 5 except for this. Comparative Example 9, the weight ratio of Na ₂ and SiO ₃ a 1: 1 powdered anhydrous sodium meta instead of silicate has a weight ratio of Na ₂ and SiO ₃ 1: 1 5H ₂ O of sodium meta been silicate is used, other than this, The other components were mixed at the same composition ratio as the same composition of Example 5. And other manufacturing conditions and environments that may affect the performance of the repair mortar were set to be substantially the same as Example 5 of the present invention, and the repair mortars of Comparative Examples 8 and 9 were produced.

Comparative Examples 10 to 13 for Examples 5 to 8 of the present invention were prepared with compositions and composition ratios as shown in Table 6 below.

unit division Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13



Powder (parts by weight) Blast furnace slag 100 100 100 100 Fly ash 100 100 100 100 Z-silica fume 20 20 20 20 Activator 2 4 24 28 aggregate 300 300 300 300 pH adjuster 9 9 9 9 Limestone 12 12 12 12 Fluidizing agent 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3

≪ Comparative Examples 10 to 13 &

As shown in Table 6, in Comparative Examples 10 to 13 of Examples 5 to 8 of the present invention, the other components except for the alkaline activator were the same as those of Example 5, and the weight of the alkaline activator was 2 , 4, 24, and 28 were mixed differently. Other repairing conditions and environments that could affect the performance of the repair mortar were prepared in the same manner as in Example 5 of the present invention, and the repair mortars of Comparative Examples 10 to 13 were produced.

≪ Test Example 3 >

Compression strength tests were conducted on the specimens of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention, respectively, in the same manner as in Test Example 1 described above. However, unlike Test Example 1, only the compressive strength of 28 days was measured. The test results are shown in Fig. 5 is a graph showing compression strengths of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention. Referring to FIG. 5, it can be seen that in all of Examples 5 to 8 of the present invention, the compressive strength at 28 days is greater than the target compressive strength of 40 MPa.

In Comparative Example 8 using liquid anhydrous sodium metasilicate instead of powdery anhydrous sodium metasilicate, the compressive strength at 28 days of age is less than the target compressive strength of 40 MPa. On the other hand, in Comparative Example 9 using 5H ₂ O sodium metasilicate in place of the powdery anhydrous sodium metasilicate, the compressive strength at 28 days of age exceeds the target compressive strength of 40 MPa. It can be seen that the compressive strengths of Comparative Examples 10 and 11 in which the weight parts of the powdery anhydrous sodium metasilicate were 2 and 4, respectively, did not reach the target compressive strength of 40 MPa. It can be seen that the compressive strength at 28 days in the case of Comparative Examples 12 and 13 in which the weight parts of the powdery anhydrous sodium metasilicate is 24 and 28, respectively, exceeds the target compressive strength of 40 MPa.

<Test Example 4>

In the same manner as in Test Example 2, the flowability tests of the repair mortars of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention were carried out. The test results are shown in Fig. 6 is a graph showing slump flows of Examples 5 to 8 and Comparative Examples 8 to 13 of the present invention. Referring to FIG. 6, in all of Examples 5 to 8 of the present invention, it can be seen that the slump flow of 10 minutes and 40 minutes after mixing exceeds the target slump flow of 180 mm.

Comparative Example 8 using liquid anhydrous sodium metasilicate instead of powdered sodium hydrosulfite, Comparative Example 9 using 5H ₂ O sodium metasilicate instead of powdery sodium hydrosulfite, Slump flow of 10 minutes and 40 minutes after mixing It can be seen that the target slump flow does not reach 180 mm. From the results of Test Examples 3 and 4, although the compressive strength at 28 days in the comparative example 9 using 5H ₂ O sodium metasilicate satisfies the target compressive strength, the comparative examples 8 and 9 do not satisfy the target slump flow The repair workability is very poor and the strength of the repair mortar is generally insufficient as compared with those of Examples 5 to 8.

Sodium metasilicate is distinguished from the hydrate form of Na ₂ SiO ₃ .nH ₂ O (n = 5, 6, 8, 9) and the anhydrous form without H ₂ O. Korean Patent No. 10-1366295 entitled " Powder type alkali activator for cement concrete, cement binder and cementless concrete using the same, " refers to an alkali activator prepared by mixing SiO ₂ : Na ₂ O in a weight ratio of 50:50 It shows the highest compressive strength and the slump loss is small. However, this prior art technique produces an alkali activator in such a manner that sodium oxide (Na ₂ O) and silicon oxide (SiO ₂ ) are completely dissolved in water, followed by drying and pulverization. The alkaline activator produced by this prior art corresponds to sodium hydrosulfate-type meta-silicate as in Comparative Example 9 since water is a substance in which sodium oxide and silicon oxide are combined as the binding water.

As described above, from the results of Test Examples 3 and 4, it can be seen that there are many differences in the strength and the fluidity duration of the maintenance mortar depending on the composition ratio of sodium metasilicate as well as the anhydrous form and the hydrate form. The present invention relates to a maintenance mortar which is not a general concrete, and it is necessary to secure a slump flow of 180 mm for at least 40 minutes necessary for the mixing, stirring, transportation, pouring and finishing of the repair mortar and at the same time to secure a compression strength of at least 40 MPa the alkali activator is Na ₂ SiO ₃ and having a weight ratio of 1 for: the composition from 0.5 to 2, and Na ₂ SiO ₃ and _{nH 2 O (n = 5,} 6, 8,9) H 2 O is not anhydrate of And anhydrous sodium metasilicate powder type was found to be suitable.

In Comparative Examples 10 and 11 in which the weight parts of the powdery anhydrous sodium metasilicate were 2 and 4 parts by weight, the slump flow of 10 minutes and 40 minutes after mixing exceeded the target slump flow of 180 mm. In Comparative Examples 12 and 13 in which the weight parts of the powdery anhydrous sodium metasilicate were 24 and 28, the slump flow of 10 minutes after mixing showed a target slump flow exceeding 180 mm but the slump flow of 40 minutes did not reach the target slump flow have. From the results of Test Examples 3 and 4, if the content of the powdery anhydrous sodium metasilicate is less than 8 parts by weight, the hardening of the repair mortar is not sufficiently cured and the strength of the repair mortar is lowered. If the amount is more than 20 parts by weight, The hardening reaction of the repair mortar progresses too quickly and the workability is deteriorated.

Examples 9 to 13 of the repair mortar of the present invention and Comparative Examples 14 to 21 were prepared as follows to evaluate the neutralization resistance and the strength of the repair portion of the concrete structure repair method according to the present invention. Particularly, Examples 9 to 13 and Comparative Examples 14 to 21 are examples for evaluating the neutralization resistance and the change in the strength of the repair portion according to the material change and the content of the pH adjuster. Examples 9 to 13 of the repair mortar of the present invention were prepared with compositions and composition ratios as shown in Table 7 below.

unit division Example 9 Example 10 Example 11 Example 12 Example 13



Powder (parts by weight) Blast furnace slag 100 100 100 100 100 Fly ash 100 100 100 100 100 Z-silica fume 20 20 20 20 20 Activator 14 14 14 14 14 aggregate 300 300 300 300 300 pH adjuster 5 7 9 11 13 Limestone 12 12 12 12 12 Fluidizing agent 3 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3 1.3

&Lt; Examples 9 to 13 >

As shown in Table 7, in Example 9 of the present invention, 100 parts by weight of blast furnace slag, 100 parts by weight of fly ash, 20 parts by weight of zirconium silica fume, 14 parts by weight of an alkali activator, 300 parts by weight of aggregate, 12 parts by weight of limestone, 3 parts by weight of fluidizing agent, 1.2 parts by weight of shrinkage reducing agent, 40 parts by weight of water and fibers having a volume of 1.3% based on the total volume of the repair mortar were mixed to prepare a repair mortar. In Examples 10 to 13 of the present invention, the other components except for the pH adjuster were the same as those of Example 9, and the pH adjuster was changed to 7, 9, 11, and 13 parts by weight, respectively.

All the components of Examples 9 to 13 of the present invention were the same as all the components of Example 1 described above. For example, a powdered OPC of 6000 brain was used as the pH adjusting agent. Like the above-described Examples 1 to 8, the repair mortars of Examples 9 to 13 were prepared with other manufacturing conditions and environments that could affect the performance of the repair mortar set to be almost the same.

Conventional cement mortar removers use only blast furnace slag and fly ash as the main binder. When these materials are reacted with an alkali activator and cured, they generally maintain the pH below 11. In order to use as a repair material for reinforced concrete, the pH of the repair material should be 12 or more to prevent the corrosion of the reinforcing bar by forming a passive film of the reinforcing bar. As described above, the present invention uses a powdered OPC of 6000 brain as a pH adjusting agent in order to adjust the pH of the repairing material to 12 or more.

Korean Patent No. 10-1472485 entitled " Geopolymer cement composition, mortar and method of using the same " refers to a method in which calcium oxide is used as a part of a material of a geopolymer cement composition so that the calcium oxide is reacted with water, However, when calcium oxide reacts with water, it shows a heat of about 100 degrees. This exothermic reaction not only threatens the safety of the workers manufacturing the mortar but also works poorly in mixing, transporting and pouring operations, resulting in deterioration of the maintenance quality. At high temperatures, as is well known, the alkali activator, blast furnace slag, fly ash As the reaction becomes active, it is difficult to maintain the slump flow of 180 mm for at least 40 minutes, resulting in a drastic drop in workability.

As another method for maintaining the pH of the maintenance mortar to 12 or more, it is possible to consider using calcium hydroxide, which is generally well known, as the material of the repair mortar. Calcium hydroxide has a molecular weight of about 74 g / mol, and it dissolves only about 1.26 g in 1 liter of water. It is not soluble in water but it has a high ionization degree. Once dissolved in water, calcium hydroxide has a strong basicity of about pH 12.5. For the purpose of enhancing the neutralization resistance of the repair mortar using such a high pH of calcium hydroxide, Comparative Examples 14 to 16 of Examples 9 to 13 of the present invention were prepared with compositions and composition ratios as shown in Table 8 below.

unit division Comparative Example 14 Comparative Example 15 Comparative Example 16
Powder
(Parts by weight) Blast furnace slag 100 100 100 Fly ash 100 100 100 Calcium hydroxide 0 One 2 Activator 14 14 14 aggregate 300 300 300 Liquid phase (parts by weight) water 40 40 40

&Lt; Comparative Examples 14 to 16 >

As shown in Table 8, in Comparative Example 14 of Examples 9 to 13 of the present invention, only blast furnace slag, fly ash, activator, aggregate, and water were fed into a mixer without adding a pH adjuster, And mixed. In order to prevent the effect of calcium hydroxide in the repair mortar from being obscured by the effect of other admixtures, a repair mortar was prepared by mixing and stirring only blast furnace slag, fly ash, calcium hydroxide, activator, aggregate and water.

In Comparative Examples 15 and 16, powdered calcium hydroxide was used in place of the powder OPC of 6000 brain as a pH adjusting agent, and the other components except for this were mixed at the same composition ratio as the same composition of Example 5. Particularly, in Comparative Example 15, the weight portion of calcium hydroxide was set to 1, and in Comparative Example 16, the weight portion of calcium hydroxide was set to 2. [ The other repairing conditions and environments that may affect the performance of the repair mortar were set to be substantially the same as Example 9 of the present invention, and the repair mortars of Comparative Examples 14 to 16 were produced.

&Lt; Test Example 5 >

Compression strength tests were performed on the specimens of Comparative Examples 14 to 16 of the present invention in the same manner as in Test Example 1 described above. Unlike Test Example 1, the compressive strength was measured up to 90 days of age. The test results are shown in Fig. 7 (a). 7 (a) is a graph showing the compressive strengths of Comparative Examples 14 to 16 of the present invention. 7 (a), in Comparative Examples 14 to 16, compressive strengths of 29 days, 28 MPa, 30 MPa, and 37 MPa according to 0, 1, and 2 parts by weight of calcium hydroxide were about 3 to 26 %, Respectively. The compressive strengths of 31 days, 31 days, 42 MPa and 41 MPa were increased by more than 40%.

The cause of this increase in compressive strength is analyzed as follows. The structure of SiO ₂ or SiO _2. Al ₂ O ₃ inside the fly ash is attacked, and Si (OH) 6 - and / or Si (OH) 6 - Al (OH) 4 &lt; - &gt; ions. These eluting ions react with Ca2 + ionized in calcium hydroxide to produce insoluble compounds by producing CSH and CAH while consuming calcium hydroxide which does not contribute to the intensity expression. The pores of the pozzolanic reaction fill the capillary pores of the mortar, thereby reducing capillary voids and tightening the texture of the mortar, thereby increasing the compressive strength.

&Lt; Test Example 6 >

According to Korean National Standard KS F 4042 "Test Method for Polymer Cement Mortar for Repairing Concrete Structure", each of the repair mortars of Comparative Examples 14 to 16 of the present invention was exposed to carbon dioxide for 8 weeks at the ages and the neutralization depth, , 2 weeks, 4 weeks, and 8 weeks, respectively. The test results are shown in Fig. 7 (b).

KS F 4042 sets the performance criterion for neutralization resistance of polymer cement mortar for concrete structure maintenance to 2mm or less in 4 weeks of exposure to carbon dioxide. Neutralization of concrete is a phenomenon that concrete which was alkaline is carbonated and becomes close to neutrality. If the carbonation depth of the concrete exceeds 2mm, the risk of rust on the rebar is increased. Accordingly, in the embodiment of the present invention, the target carbonation depth is set at 2 mm for four weeks at a time.

 7 (b) is a graph showing carbonation depths of Comparative Examples 14 to 16 of the present invention. Referring to FIG. 7 (b), it can be seen that the carbonation depths of all the Comparative Examples 14 to 16 of the present invention are much deeper than the target carbonation depth of 2 mm. The reason for this increase in carbonation depth is analyzed as follows. Calcium hydroxide has very low solubility in water. As described above, when the calcium hydroxide is added in an amount of 2 parts by weight or more due to the property of being insoluble in water, the calcium hydroxide is eluted to the hardened mortar surface to form a latence layer. As a result, the amount of calcium hydroxide that inhibits neutralization in the repair mortar is gradually reduced to increase the carbonation depth.

Therefore, in order to increase the strength of the repair mortar, it is effective to put calcium hydroxide in about 2 parts by weight. However, for the purpose of increasing the alkalinity of the interior of the repair mortar to prevent carbonation, the calcium hydroxide is exhausted by the pozzolanic reaction with fly ash which is not dissolved in water and used as a binding material of the repair mortar instead of cement, It is impossible to solve the problem of suppressing the neutralization of the repair mortar. In conclusion, the use of calcium hydroxide as an admixture for the purpose of increasing the pH of the repair mortar is not appropriate considering the low solubility of calcium hydroxide.

Comparative Examples 17 to 21 of Examples 9 to 13 of the present invention were prepared with composition and composition ratios as shown in Table 9 below.

unit division Comparative Example 17 Comparative Example 18 Comparative Example 19 Comparative Example 20 Comparative Example 21



Powder (parts by weight) Blast furnace slag 100 100 100 100 100 Fly ash 100 100 100 100 100 Z-silica fume 20 20 20 20 20 Activator 14 14 14 14 14 aggregate 300 300 300 300 300 pH adjuster 0 3 15 17 19 Limestone 12 12 12 12 12 Fluidizing agent 3 3 3 3 3 Shrinkage abatement agent 1.2 1.2 1.2 1.2 1.2 Liquid phase (parts by weight) water 40 40 40 40 40 Fiber (volume ratio) Polyvinyl alcohol 1.3 1.3 1.3 1.3 1.3

&Lt; Comparative Examples 17 to 21 &

As shown in Table 9, in Comparative Example 17 of Examples 9 to 13 of the present invention, the pH adjuster was not added to the mixer, and the other ingredients were mixed in the same composition ratio as in Example 9. In Comparative Examples 18 to 21, the other components except for the pH adjuster were the same as those of Example 9, and the weight parts of the pH adjusters were changed to 3, 15, 17, and 19, respectively. Other repairing conditions and environments that could affect the performance of the repair mortar were set to be substantially the same as Example 9 of the present invention, and the repair mortars of Comparative Examples 17 to 21 were produced.

&Lt; Test Example 7 >

In the same manner as in Test Example 5 described above, the neutralization resistance performance tests of the repair mortars of Examples 9 to 13 and Comparative Examples 17 to 21 of the present invention were carried out. The test results are shown in Fig. 8 is a graph showing carbonation depths of Examples 9 to 12 and Comparative Examples 17 and 18 of the present invention. Referring to FIG. 7, in Examples 9 to 12 of the present invention, it can be seen that the depth of carbonation at the age of 4 is less than the target carbonation depth of 2 mm. On the other hand, in Comparative Example 17 in which the pH adjuster is not used and Comparative Example 18 in which the weight adjuster is 3 parts by weight, the depth of carbonation at the age of 4 exceeds the target carbonation depth of 2 mm. On the other hand, in Example 13 and Comparative Examples 19 to 21 of the present invention, the change in the depth of carbonation was almost the same as in Example 12, and the graph was superimposed on the graph of Example 12 and its illustration was omitted.

The reason why general OPC powder is used is 3000 brains or high powder OPC of 6000 brains or more through OPC milling with a ball mill or the like. In the case of the repair mortar of the present invention, since the curing speed is faster than that of ordinary portland cement, In order to prevent the pH from dropping due to the reaction, it is necessary to shorten the generation time of the calcium hydroxide, which is a product due to the hydration reaction of the high-strength common portland cement. 3000 Brain OPC particles have an average particle diameter of 20 탆 and a hydration thickness of 5 to 10 탆 for 28 days. Half of the OPC particles are easy to be untreated. However, when the average particle diameter is halved by 6000 brains, Calcium hydroxide is sufficiently generated in the solution.

From the results of Test Example 7, it can be seen that as the OPC content increases, the carbonation depth drastically decreases in the section where the powder OPC content of the 6000 brain is increased to 5 parts by weight, and the OPC content in the range of 5 to 13 parts by weight And the depth of carbonation decreases as the water content increases. As described above, in the interval of 13 parts by weight or less, the compressive strength is increased due to the hydration reaction caused by the use of the high-powder cement at the same time as the polymerization reaction of the maintenance mortar and the calcium hydroxide is generated simultaneously with the inside of the repair mortar, Respectively. However, in the section exceeding 13 parts by weight, there is no significant change in the depth of carbonation even when the OPC content is increased.

6000 Brain Powder OPC reacts with zirconium silica fume to exhibit the effect of improving the strength of the repair mortar. In other words, the zirconium silica fume contained in the repair mortar should have calcium hydroxide to fill the pores in the repair mortar through the pozzolanic reaction and exhibit high strength. However, in the absence of calcium hydroxide, the strength enhancement effect is insignificant. Therefore, the high powder OPC of 6000 brain is used in the present invention for the purpose of increasing the pH of the repair mortar and increasing the strength through reaction with zirconium silica fume.

The main object of the present invention is to reduce the amount of greenhouse gases that cause global warming by reducing the amount of carbon dioxide generated in the cement production process by using industrial byproducts such as blast furnace slag and fly ash as environmentally friendly inorganic polymers have. Therefore, it is preferable to minimize the content of OPC used as a pH adjuster in the present invention. That is, when the content of the powdered OPC in the 6000 brains is less than 5 parts by weight, the neutralization of the repair mortar rapidly proceeds and the rebound of the reinforcing steel is highly likely to rust and the strength of the repair mortar is lowered. Neutralization resistance performance is insignificant and it is not environmentally friendly due to an increase in carbon dioxide emissions.

The preferred embodiments, comparative examples and test examples of the present invention have been described so far. Although the present invention has been described in detail by way of examples, comparative examples and test examples, it is not intended to limit the present invention, but merely to demonstrate the present invention. Therefore, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (7)

Removing the concrete deterioration portion of the concrete structure;
Removing rust of the exposed reinforcing bars from the concrete deteriorated portion;
Preparing a repair mortar by stirring a mixture comprising blast furnace slag, fly ash, zirconium silica fume, aggregate, alkali activator, and water; And
And applying the prepared repair mortar to the concrete structure,
The mixture is prepared by mixing 90 to 110 parts by weight of blast furnace slag, 90 to 110 parts by weight of fly ash slag, 100 parts by weight of fly ash so that the slump flow of the repair mortar is maintained at least 40 minutes from the mixing point of the mixture, 15 to 30 parts by weight of zirconium silica fumarate and 8 to 20 parts by weight of an alkali activator,
The mixture further comprises 5 to 20 parts by weight of limestone, 0.1 to 6 parts by weight of a fluidizing agent, 0.05 to 3 parts by weight of a shrinkage reducing agent, and fibers having a volume of 0.5 to 2% based on the total volume of the repair mortar Concrete structure repair method. The method according to claim 1,
Wherein the mixture further comprises 250 to 350 parts by weight of aggregate and 30 to 50 parts by weight of water. 3. The method of claim 2,
The alkali activator is an anhydrous form of Na ₂ SiO ₃ .nH ₂ O (n = 5, 6, 8, 9) free of H ₂ O and having a weight ratio of Na ₂ and SiO ₃ of 1: Characterized in that anhydrous sodium metasilicate (Na ₂ SiO ₃ ) is used. 3. The method of claim 2,
Wherein the mixture further comprises 5 to 13 parts by weight of a pH adjusting agent. 5. The method of claim 4,
Wherein the pH adjuster is a powdered ordinary Portland cement (OPC) having a viscosity of 6000 cm &lt; 2 &gt; / g of brain powder. delete The method according to claim 1,
Applying a liquid film curing type curing agent to the surface of the reinforcing mortar applied to the concrete structure; And
Further comprising the step of peeling the film-form curing agent from the surface of the repair mortar after the applied curing agent is cured in a film form.

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