KR101308084B1 - Repairing method of reinforced concrete structures using inorganic self-healing materials - Google Patents

Abstract

PURPOSE: A self-healing repairing and restoring method of a concrete structure using inorganic self-healing materials is provided to reduce repairing and restoring costs by improving repairing and restoring effects without additional works due to additional cracking. CONSTITUTION: A self-healing repairing and restoring method of a concrete structure using inorganic self-healing materials comprises the following steps: grinding and drilling a cracking part and applying a permeable liquid reaction material to the drilled part; filling a self-healing cement paste which is a mixture of a binding material mixed with cement and an inorganic self-healing blending material, a water reducing agent, and water; and applying self-healing cement mortar which is a mixture of cement, a binding material with an inorganic self-healing blending material, fine aggregates, and water. [Reference numerals] (AA) Amount of water percolation (ml/sec); (BB) Example 1; (CC) Example 2; (DD) Example 3; (EE) Comparative example 1

Description

Repairing Method of Reinforced Concrete Structures Using Inorganic Self-healing Materials

The present invention relates to a method for repairing and repairing damage caused by cracks, deterioration, etc. of concrete structures, and more specifically, inorganic self-healing properties of self-healing properties that can be restored and healed on their own when treated on damaged parts of concrete structures. The present invention relates to a self-healing repair and recovery method for concrete structures that can improve the repair and recovery effect using ash.

Concrete is the most widely used material on earth, and most structures, including civil engineering, construction, and plants, are built using concrete. Concrete gradually degrades and ages after a certain period of time after casting or molding. In particular, when a crack occurs in the concrete, harmful air, moisture, and chemicals penetrate the concrete, thereby further degrading the performance of the concrete. Furthermore, the corrosion of reinforcing steel in the concrete structure occurs due to moisture, chloride ions, etc. penetrating into the concrete, resulting in additional cracking or dropping of the concrete. This can lead to the collapse of the structure.

If the concrete structure is damaged, the performance of the concrete structure does not reach the design life. Therefore, a method of controlling the crack during construction of the concrete structure or a repair and recovery method in case of crack or deterioration have been proposed. The crack control method is a method in which various fibers which can reduce the occurrence of cracks are mixed and placed in concrete or a wire mesh is installed inside the concrete structure. The repair and repair method is a polymer resin such as a crack part or a deterioration part. It is a method of applying polymer cement-based repair materials with improved physical performance, durability, and workability.

However, the existing crack control technology could not completely prevent cracks in concrete structures, so additional repairs were necessary and could not be a fundamental countermeasure. There is a disadvantage required.

The present invention was developed to improve the shortcomings of the conventional concrete repair and recovery method, using the inorganic self-healing material of the self-healing properties that can restore and heal itself when treated to the damaged part of the concrete structure to repair and repair effect There is a technical challenge in providing new repair and recovery techniques that can be improved.

In order to solve the above technical problem, the present invention is a method for repairing and repairing a concrete structure, in which an inorganic self-healing admixture including a water-soluble inorganic gelling agent, an alkali sulfate, sodium aluminate, water-soluble silica, and a fluorine-based retardant is mixed. Provided is a repair and repair method for a concrete structure, characterized in that the self-healing cement paste or cement mortar is treated to a part to be repaired and repaired. Here, when the self-healing cement paste or cement mortar is treated on the damaged part of the concrete structure, the self-healing inorganic self-healing material is restored.

According to the present invention, the following effects can be expected.

First, since the present invention uses inorganic self-healing materials of self-healing properties that can be restored and healed itself when processed to the damaged portion of the concrete structure, no additional work is required by additional cracking, thereby improving the repair and recovery effect This can reduce maintenance demand and reduce related costs.

Second, since the present invention uses a cement-based inorganic material as a repair and recovery material, it can be integrated with the concrete matrix while securing safety after completion of the repair and repair work.

1 is a schematic diagram of a crack repair method.
Figure 2 shows the permeability test process of the specimen applied crack repair method.
3 shows a concrete permeability test apparatus and a concrete permeability test body.
Figure 4 shows the test results for the permeation test of the specimen applied crack repair method.
Figure 5 shows the electron microscope observation photograph before and after the permeation test of the specimen applied crack repair method.
6 is a schematic diagram of a cross-sectional recovery method.
Figure 7 shows the test results for the permeability test of the specimen applied to the cross-sectional recovery method.

Hereinafter, the present invention will be described in detail according to preferred embodiments.

The present invention relates to a method for repairing and repairing damage to a concrete structure, and self-healing incorporating an inorganic self-healing admixture comprising a water-soluble inorganic gelling agent, an alkali sulfate, sodium aluminate, a water-soluble silica, and a fluorine-based retardant The cement paste or cement mortar is characterized in that it is treated to a part to be repaired and repaired. Herein, the inorganic self-healing material admixture includes 5 to 78 parts by weight of a water-soluble inorganic gelling material, 10 to 45 parts by weight of alkali sulfate, 10 to 25 parts by weight of sodium aluminate, 1 to 15 parts by weight of water-soluble silica, and 1 to 10 fluorine-based retardants. Composition in parts by weight is preferred in view of reactivity and economics.

In inorganic self-healing admixtures, the water-soluble inorganic gelling agent is an inorganic coagulant, which initially contributes to the physicochemical coagulation phenomenon and maintains the gelation form after curing, thereby producing delayed ettringite through elution of ions when water is supplied. For example, aluminum sulfate (Al ₂ (SO ₄ ) ₃ · xH ₂ O), a representative example of a water-soluble inorganic gelling agent, is an inorganic electrolyte that is dissolved in water to bring the surface potential of particles in the liquid to almost zero, thereby eliminating the electrical repulsion between the particles. by giving cause agglomeration of high viscosity, in addition it is soluble in water SO4 ^{2 -} ions and Al ^{3 +} ions to react with the Ca ²⁺ ions in a Ca (OH) ₂ in cement hydrate by supplying _{Ettringite (3CaO · Al 2 O 3} · 3Ca (SO) ₄ 32H ₂ O) contributes to the production. A water-soluble inorganic gelling agent is appropriate to adopt at least one of aluminum sulfate and potassium aluminum sulfate (AlK (SO ₄ ) ₂ · xH ₂ O), and considering the reactivity, specific gravity is 1.5-1.9, solubility of 8% or more ( 25 ° C.), and the Al ₂ O ₃ content is preferably 15% or more.

Alkaline sulfate in inorganic self-healing admixtures contributes to the restoration of cracks by producing expandable hydrates (ettringite, 3CaO · Al ₂ O ₃ · 3Ca (SO) ₄ · 32H ₂ O) when water is supplied, as shown in the equation below.

3R ₂ SO ₄ + 3CaOAl ₂ O ₃ + 3Ca (OH) ₂ + 32H ₂ O-> 3CaOAl ₂ O ₃ 3Ca (SO) ₄ 32H ₂ O + 6R (OH)

In the above reaction formula _{3CaO · Al 2 O 3, 3Ca} (OH) 2 is fed in the cement component, the hydration early cement is 3CO · Al ₂ O ₃ of cement sulfate ^ion, because the reaction dramatically and (SO4 ²⁾ Fluidity is secured by delaying the hydration reaction in which xCaOyAl ₂ O ₃ zH ₂ O is produced. In addition, at the beginning of the age, it contributes to the strength increase by promoting the hydration reaction of cement by providing an alkaline environment as shown in the following reaction formula.

_{(XCaO + YSiO 2 + ZH 2} O) (Condition: pH 12 ~ 13) -> xCaO · yAl 2 O 3 · zH 2 O

In the above scheme, CaO and SiO ₂ are supplied from the cement component, and the environment of pH 12 ~ 13 is the condition of pH 12 ~ 13 due to the generation of ROH by dissolving Alkali Sulfate, and Ca generated during the hydration of cement. The production of (OH) ₂ also contributes to pH conditions. The calcium silicate hydrate x CaO · yAl ₂ O ₃ · zH ₂ O produced through this reaction is a representative cement hydrate that exhibits strength and shows excellent strength.

Such alkali sulfates include at least 35-70% by weight of CaSO ₄ , CaSO ₄ 2H ₂ O, CaSO ₄ 1 / 2H ₂ O and Na ₂ SO ₄ , K ₂ SO ₄ At least one of 30 to 65% by weight of the mixture is preferably used when considering the reactivity.

In inorganic self-healing admixtures, sodium aluminate (Al ₂ O ₃ · nNa ₂ O) generally produces NaOH and Al (OH) ₃ when dissolved in water, indicating alkalinity (Al ₂ O ₃ · nNa ₂ O + 5H _2). O-> xNaOH + yAl (OH) ₃ ), the NaOH produced at this time increases the pH of the cement paste to promote the hydration reaction of the cement to quickly generate calcium silicate hydrate (xCaO · yAl ₂ O ₃ · zH ₂ O). It contributes to the initial precipitation and growth of self-healing precipitates, and Al (OH) ₃ forms Ettringite together with aluminum sulfate to contribute to the early age strength. Sodium aluminate has a chemical formula of Al ₂ O ₃ nNa ₂ O (n = 1.3 ~ 1.8), Na ₂ O content of 35% by weight or more, the apparent density of 0.4 ~ 0.7g / cm 3d is preferable considering the reactivity Do.

In inorganic self-healing admixtures, the water-soluble silica contributes to the homogeneous mixing and dispersing of the admixtures, thereby ensuring the manufacturability and stable performance of the admixtures. In addition, it becomes a filler between cement particles, and as the hydration reaction of the cement progresses, the medium and long-term age strength is enhanced, and further, the calcium silicate hydrate (xCaO, yAl ₂ O ₃ , zH ₂ O) is generated by silicate ions to increase the medium and long-term age strength. Sometimes. Water-soluble silica is suitable if at least one of silica fume and reactive silica powder is suitable.In consideration of the effect, the particle size is 5㎛ or less, the SiO ₂ content is 90% or more, the specific gravity is 2.1 ~ 2.8, and the powder degree is 10,000 ~ 200,000㎠ / It is preferable that it is g.

In inorganic self-healing admixtures, fluorine-based retardants (KF · nH 2 O, n = 0 to 2) control the initial setting rate by alkali ions, and also act to enhance the mixing and dispersibility of the admixture in the powder state.

The self-healing cement paste or cement mortar into which the inorganic self-healing admixture having the above-described constitution is mixed soon becomes an inorganic self-healing material.

On the other hand, when conducting the repair and repair work of the concrete structure, before the inorganic self-healing material, that is, the self-healing cement paste or the cement mortar, is applied, the penetration type liquid reaction material by the alkali metal ionizer is applied to the repair and recovery part. It is preferable to. Infiltration type liquid phase reaction material by alkali metal ionizer contributes to improving the reactivity and adhesion performance of inorganic self-healing material (self-healing cement paste or cement mortar) by creating strong alkali environment. Here, the penetration liquid phase reactant is preferable when considering the reactivity and adhesion performance of the aqueous alkali silicate solution having the characteristics as shown in the following [Table 1].

Infiltration Liquid Reactant SiO ₂ / R ₂ O molratio
(R = Na, K) importance Solid content? (%) 2.80 ~ 3.33 1.1 ± 0.05 5-20

Repairing and repairing the concrete structure according to the present invention can be divided into three types depending on the type of damage and the specific treatment method.

The first is to handle the case where the part to be repaired and repaired is the crack (cracker repair method). In this method, each crack is treated separately. First, after grinding and drilling, the penetration liquid reaction material is applied to the perforated part, and then the self-healing cement paste is filled into the perforated part, and finally the self-healing cement paste. Proceed to the process of applying self-healing cement mortar to the filled surface. The self-healing cement paste includes a binder composed of 50 to 75% by weight cement and 25 to 50% by weight inorganic self-healing admixture, 0.05 to 1% water reducing agent of the binder, and 15 to 30% by weight water of the binder. The self-healing cement mortar contains a binder composed of 50 to 80% by weight cement and 20 to 50% by weight inorganic self-healing admixture, 30 to 70% by weight of the aggregate, and 20 to 40% by weight of the binder. . This blending method is the result of considering filling or rubbing workability, and when blended, it is blended into a paste that can be filled intactly without falling down, and when applied, it is not stiff and flows down to a predetermined thickness. It is formulated with a mortar of true compounding so that it can be applied. On the other hand, the penetration liquid reaction material is applied so that it is sufficiently wet regardless of the absorption performance of the crack, and the self-healing cement paste is filled with the self-healing cement mortar so as to be protected from being exposed after filling the crack to the maximum. Correct to. After coating with self-healing cement mortar, it can be finished with a coating or finish.

In the crack repair method, the drilled crack is drilled to a diameter of 10 mm or more, a depth of 30 mm or more, and a space spacing of 60 mm or less in order to ensure self-healing performance, and the penetration liquid reaction material is coated to be sufficiently wet regardless of the absorption performance of the crack. After applying the permeation type liquid phase reaction material, it is preferable to treat the inorganic index material in some cases. The mineral index material is to reduce the water leakage from the inside of the coated surface during filling for a certain time to reduce the damage caused by the leakage pressure, it is suitable if the main raw material is bentonite. After the inorganic index material is treated, the self-healing cement paste is filled to the inside of the perforated part completely. After filling, the permeable liquid reactant is additionally applied before the filler is cured. Apply self-healing cement mortar with a coating thickness of at least 3 mm before drying.

The second method is to repair and repair the surface when the part to be repaired and repaired is a crack (surface repair method). This method collects and treats individual cracks in the case where the part to be repaired and repaired is a crack, and as a result, self-healing cement mortar is used. First of all, grinding is applied to the infiltration liquid phase reaction material, and then the self-healing cement mortar is applied to the cracking process. The self-healing cement mortar is a binder composed of 80 to 95% by weight of cement and 5 to 20% by weight of inorganic self-healing admixture, 50 to 300% by weight of fine aggregate of the binder, 0.05 to 1% by weight of the binder, and 20 to 20% of the binder. It contains 40% by weight of water, which is a result of considering physical properties such as strength and adhesion. Permeable liquid reactants should be applied especially wet in areas with high absorbency, and self-healing cement mortar should be applied with a thickness of 10mm or more. Self-healing cement mortar can be finished with a coating or finish after surface repair.

Thirdly, when the repair and recovery part is a deterioration part, the section is recovered and treated (section recovery method). This method first proceeds to the process of chipping and cleaning the deterioration section, removing the rust of the reinforcing bar, and then rust-preventing it, and then applying an infiltration liquid reaction material, and finally applying self-healing cement mortar to the deterioration section. Here, the self-healing cement mortar may be used in the same manner as the surface repair method described above, and the self-healing cement mortar should be coated with a construction thickness of 10 mm or more. After self-healing cement mortar is applied and the cross-section is restored, it can of course be finished with a coating or finishing material.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1 Crack Repair

1. Preparation of inorganic self-healing materials

The self-healing cement paste of Table 2 below and the self-healing cement mortar of Table 3 were prepared.

2. Permeability test

After one day after forming a separate circular concrete specimen (Ø100mm X 200mm), the mold was demoulded and steam cured for 7 days to produce the final circular concrete specimen, and then cracked in the same manner as in FIGS. 1 and 2 for the circular concrete specimen. After the maintenance, a permeation test was performed. That is, after the circular concrete specimens are split, the cracks are controlled so that the crack interval is 0.2 to 0.3 mm, and then the bottoms of the specimens are perforated to fill the perforated parts with self-healing cement paste according to [Table 2], and according to [Table 3]. Apply self-healing cement mortar to a thickness of 3mm to perform crack repair, and then water of constant height (12cm, water pressure 1.2Kpa) is poured over the crack-repaired circular concrete test specimen, and continuously for a certain time with the start of the permeation test. Permeability test was carried out by maintaining the water height of the upper part of the test body and measuring the amount of water permeated through the test body for a predetermined time (5 minutes) according to the age. Apparatus and test specimen used in such a permeability test is shown in FIG. Permeability test results are shown in the following [Table 4] and FIG.

Permeability change division Example 1 Example 2 Example 3 Comparative Example 1 Pitching period
(Work) Permeability
(Ml / s) Pitcher Reduction Rate
(%) Permeability
(Ml / s) Pitcher Reduction Rate
(%) Permeability
(Ml / s) Pitcher Reduction Rate
(%) Permeability
(Ml / s) Pitcher Reduction Rate
(%) 0 days 0.370 0 0.380 0 0.340 0 0.392 0 1 day 0.214 42.1 0.160 57.9 0.160 52.9 0.301 23.1 3 days 0.078 78.9 0.047 87.6 0.045 86.7 0.230 41.0 5 days 0.032 91.3 0.025 93.4 0.022 93.5 0.190 51.3 7 days 0.020 94.5 0.020 94.7 0.017 95.0 0.184 53.8 14 days 0.015 96.0 0.010 97.3 0.013 96.2 0.164 59.0 28th 0.011 97.0 0.006 98.3 0.008 97.7 0.138 64.6

As shown in [Table 4] and FIG. 4, in Examples 1 to 3, the permeability decreased significantly (the permeability reduction rate was increased) from the 3rd day of the permeation day, and the permeability reduction rate was 97 to 98.8% on the 28th day. Excellent performance could be confirmed. However, Comparative Example 1 showed a partial permeability decrease, but showed a low permeability reduction rate performance compared to Examples 1-3.

3. Crack Healing Form Before and After Pitching Experiment

Before and after the water permeation test of the crack repair method applied cracks were observed by electron microscopy, the results are shown as shown in FIG. As can be seen in Example 1, the crack healing shape due to the product could be confirmed, but in Comparative Example 1 there was no product.

Example 2 Sectional Restoration Method

1. Preparation of inorganic self-healing materials

Self-healing cement mortar of the following [Table 5] was prepared.

2. Permeability test

The cross-sectional recovery method was performed in the same manner as in FIG. 6, and the permeability test was performed on the recovered specimen by applying the cross-sectional recovery method. Permeability test was performed in the same manner as the crack repair method of [Example 1], and the results are shown in FIG. As shown in FIG. 7, as the time elapses in Example 4, the permeability may be remarkably reduced as the healing substance is generated.

Claims (7)

delete As a method of repair and repair of concrete structures,
Treat self-healing cement paste or cement mortar with mineral self-healing admixtures in the areas to be repaired and repaired,
As the inorganic self-healing admixture,
5 to 78 parts by weight of a water-soluble inorganic gelling agent by at least one of Al ₂ (SO ₄ ) ₃ and AlK (SO ₄ ) ₂ ; Alkaline sulphate consisting of 30 to 65% by weight of at least one of CaSO ₄ , CaSO ₄ 2H ₂ O, CaSO ₄ 1 / 2H ₂ O and at least one of Na ₂ SO ₄ , K ₂ SO ₄ 30-65% by weight 45 parts by weight; 10-25 parts by weight of sodium aluminate having a Na ₂ O content of 35% by weight or more and an apparent density of 0.4-0.7 g / cm 3; 1 to 15 parts by weight of water-soluble silica by at least one of silica fume and reactive silica powder; 1 to 10 parts by weight of a fluorine-based retardant; self-healing repair and recovery method of the concrete structure, characterized in that the treatment using the composition. 3. The method of claim 2,
Before the self-healing cement paste or cement mortar, self-healing repair and recovery method of the concrete structure, characterized in that the liquid-repellent infiltration type by the alkali metal ionizing agent is applied to the part to be repaired and repaired. 4. The method of claim 3,
In the case where the parts to be repaired and repaired are cracks, the individual cracks are respectively
After grinding and drilling, apply the penetration liquid reaction material to the perforations.
Cracking a self-healing cement paste containing a binder composed of 50 to 75% by weight of cement and 25 to 50% by weight of inorganic self-healing admixture, 0.05 to 1% by weight of binder, and 15 to 30% by weight of water of binder. After charging inside the compartment,
On the surface filled with self-healing cement paste, a binder composed of 50 to 80% by weight of cement and 20 to 50% by weight of inorganic self-healing admixture, 30 to 70% by weight of fine aggregate of the binder, and 20 to 40% by weight of water of the binder Self-healing repair and recovery method for a concrete structure, characterized in that by applying the self-healing cement mortar blended. 5. The method of claim 4,
Self-healing repair and recovery method for the concrete structure, characterized in that the self-healing cement paste is filled into the perforated area after the infiltration liquid phase reaction material is applied to the inorganic index material. In paragraph 3
If the part to be repaired and repaired is a crack, the individual cracks are put together,
Grinding to apply the penetration liquid reactant,
Binder composed of 80 to 95% by weight of cement and 5 to 20% by weight of inorganic self-healing admixture, 50 to 300% by weight of fine aggregate of binder, 0.05 to 1% by weight of binder, 20 to 40% by weight of binder Self-healing repair and recovery method for a concrete structure, characterized in that at the same time apply to the cracked self-healing cement mortar blended. In paragraph 3
If the part to be repaired and repaired is a deterioration part,
After chipping and cleaning the deterioration part and removing the rust of the reinforcing bar, the anti-rust treatment was applied, and then the penetration liquid reaction material was applied.
Binder composed of 80 to 95% by weight of cement and 5 to 20% by weight of inorganic self-healing admixture, 50 to 300% by weight of fine aggregate of binder, 0.05 to 1% by weight of binder, 20 to 40% by weight of binder Self-healing repair and recovery method for a concrete structure, characterized in that the application of self-healing cement mortar, including the blend.

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