KR100915422B1 - Composition for Crack Reparing of Concrete Structure - Google Patents

Abstract

The present invention relates to an economical and environmentally friendly crack repair composition incorporating cutting-edge technology for the performance recovery and performance improvement of a crack-produced concrete structure, the nano-structured inorganic crack repair material according to the invention cracked concrete structure The mechanical and durability characteristics of nano synthetic inorganic crack repair materials were evaluated comprehensively.

As a result of evaluating the mechanical properties of the crack repair composition according to the present invention showed excellent adhesion performance in the standard and dry and repeated conditions, the results of salt penetration and diffusion, neutralization and saline resistance also showed very good results. Therefore, when the performance degradation due to cracking is required to repair the concrete structure, using the crack repair composition according to the present invention has the effect of improving the performance and performance of the concrete structure.

Description

Composition for Crack Reparing of Concrete Structure

The present invention relates to an economical and environmentally friendly crack repair composition incorporating advanced technology for the performance recovery and performance improvement of cracked concrete structure.

In general, concrete is a discontinuous, anisotropic and inhomogeneous hardened body composed of a mixture of cement, aggregate, water, and other miscible materials, and its physical and chemical properties are very diverse and complicated. Such concrete has many voids or microcracks from the manufacturing stage due to the hydration reaction, bleeding, heat of hydration, plastic shrinkage and the different properties of the materials. When concrete hardens, microcracks generated at the manufacturing stage grow into cracks due to various factors such as dry shrinkage, thermal stress and external load.

These concrete cracks are caused by various factors, and their effects on the structure also vary. Cracks can be categorized into cracks due to concrete material factors, cracks due to design errors, cracks due to poor construction, and cracks due to load action.The cracks generated are the durability of concrete members, the drop in load capacity due to reinforcement corrosion, It affects water tightness and airtightness, aesthetics, etc.

Cracks occurring in concrete structures severely degrade the performance of concrete, and further shorten the lifespan by losing their role as structures. In addition, since it is the main cause of deterioration of all functions such as the strength, durability, and waterproofness of a structure, it may cause serious problems in the safety and usability of the structure. Therefore, it is natural to not neglect it as a minute crack that does not directly affect the durability of the structure. will be.

The performance degradation due to the cracking of the concrete structure has a problem in that a considerable cost is required for reinforcing reinforcement, construction and maintenance of the bypass road. In addition, if the structure collapses, its spillover effects not only provide economic and technical factors, but also lead to anxiety for the state and technicians, leading to weakened competitiveness and loss of credibility in the international community.

In recent years, the domestic construction environment is changing to reinforcement for maintenance and improvement of existing facilities rather than new investments. Interest has recently surged. However, in Korea, the development of repair materials and construction methods for repairing and reinforcing concrete structures is much less than in advanced countries. In the case of existing repair materials, import and use of repair materials intensify technical dependency and unnecessary outflow of foreign currency. Not only are they increasing, but there are no reinforcing reinforcement materials and construction methods that combine advanced technologies such as ET, IT, and mechatronics technologies that have recently been developed.

The present invention was created to solve the problems of the conventional technology as described above, by contributing to the national competitiveness by developing an economical and environmentally friendly crack repair composition incorporating advanced technology to utilize in the construction industry, ultimately It is intended to contribute to industrial development.

In order to solve the above problems, the present invention is a crack repair composition for forming a protective film by applying to the surface of the concrete structure, in the powder-based inorganic crack repair material, a combination of liquid nano silicate and liquid nano acrylic emulsion as a binder The powder type inorganic crack repair material has a specific gravity of 1.62, the liquid nanosilicate has a specific gravity of 1.01, a solid content of 2.5% by weight, the nanoacrylic emulsion has a specific gravity of 1.02, and a solid content of 50. It provides a crack repair composition, characterized in that the weight%.

Hereinafter, with reference to the accompanying drawings and diagrams, the experiment on the mechanical properties and durability of the crack repair composition and the control according to the present invention was performed.

Experiment overview

1. Cement

A typical Portland cement with a specific gravity of 3.15 and a specific surface area of 3,112cm2 / g was used.

2. Aggregate

For coarse aggregates, steel sand and coarse aggregates with a specific gravity of 2.50 and an assembly rate of 2.30 were used as crushed stone with a maximum dimension of 25 mm and a specific gravity of 2.62.

3. Composition for crack repair according to the present invention

The crack repair composition according to the present invention is a liquid nanosilicate and a liquid nano acrylic (polymer) emulsion binder added to improve adhesion with the ground concrete based on the powder-based inorganic crack repair material. The main components and physical properties of the crack repair composition are shown in Table 1 below.

4. Preparation of test specimen In order to evaluate the performance of the crack repair composition and the control crack repair material (or crack repair composition) according to the present invention was prepared as follows. The water-cement ratio of the ground concrete used to apply the crack repair material (or crack repair composition) was set to 45%, slump 10 ± 1.5, and air volume 4.5 ± 1.5. After curing for 28 days after the production was subjected to dry curing for 3 days. Thereafter, after the crack repair material (or crack repair composition) was applied to the base concrete, curing was performed for a predetermined time. The test body preparation method according to the present invention is shown in Table 2.

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Table 2. Test piece fabrication method of crack repair material (or crack repair composition) Crack repair material (or crack repair composition) Constellation Manufacturing method NC Ground concrete S1 powder 200 g of water was added to 1000 g of a powder type inorganic crack repair material, and the mixture was used. S2 Powder + liquid Powder-based inorganic crack repair materials were used after the first coating of the liquid nanosilicate binder. S3 Powder + liquid 200 g of water and 10 g of liquid nanosilicate binder were added to 1000 g of a powder-type inorganic crack repair material, followed by stirring well. S4 Powder + liquid 180 g of water, 10 g of liquid nanosilicate binder, and 20 g of liquid nano acrylic emulsion binder were added to 1000 g of a powder-type inorganic crack repair material, followed by stirring. Experiment method

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1. Evaluation of adhesion performance in standard condition

After applying the crack repair material (or crack repair composition) on the surface of the test body, as shown in Fig. 1 (a) put the top tension steel jig, and after bonding, remove excess adhesive around. The maximum tensile load was obtained by making a groove along the periphery of the steel jig and applying a tensile force in the vertical direction with respect to the surface of the test body by using a steel tension plate and a base tension steel jig as shown in FIG. The evaluation after the test is evaluated according to the dropping state and the pull-out adhesive strength of the tensioning jig at the time of measurement.In the case of the dropping state, the base (base) breakdown, the surface dropping of the base and the coating layer, the breakage of the coating layer, the coating layer and the tensile It can be divided into 4 stages of eliminating the boundary of the jig.

2. Evaluation of adhesion performance in wet and dry condition

In order to accelerate the deterioration of the test specimens, the wet and dry repeat strength test was performed by immersion test using 1 cycle of making a frame on the specimen, immersing in solution for 2 days, and drying for 2 days. The test was carried out.

3. Chlorine Ion Penetration Resistance Test

1) Calculation of passing current and total passing charge

The current flowing through the test body was measured at 30-minute intervals using a data logger (TDS 303) while energizing a 60 V DC voltage at both ends of the concrete test body for 6 hours. After adding the potential difference, the integrated value of the current with respect to time was taken from the current measured in units of 30 minutes, and the total pass charge was calculated by Equation (1) below.

(Equation 1)

Based on the total amount of charges calculated from Equation (1) above, the penetration resistance against chlorine ions is determined by comparing with the range shown in <Table 3>.

2) Estimation method of diffusion coefficient by facilitation test

The chlorine ion diffusion coefficient in the abnormal state by the potentiometric acceleration test method was calculated as the diffusion coefficient (Dcpd) by the chlorine ion penetration depth, and the equation is shown in Equation 2 below.

(Equation 2)

4. Promote neutralization test

After curing the cement cured body produced in water at 20 ± 1 ℃ for 14 days, the surface of the cured body was coated with a protective coating material for concrete to conduct a neutralization test. Acceleration test conditions were set to a temperature of 30 ℃, relative humidity 60%, CO 2 concentration 10%. The neutralization depth was measured 28 days after the palpation from the palpation test. Neutralization depth evaluation was performed by spraying 1% phenolphthalein solution (KS M 0015) on the splitting surface after the splitting of the concrete cured body, and measuring the uncolored concrete neutralizing portion that did not turn pink.

5. Salt water resistance test

The salt water resistance test was performed by immersion at 20 ° C for 15 days using sodium chloride (NaCl) solution (3 w / v%) at a concentration similar to that of seawater. The specimens were taken out, washed, and left for 2 hours before swelling. , Peeling, softening, holes were visually observed and color change was observed in comparison with the reference specimen. Unless otherwise specified, a range of about 10 mm in width around the specimen and at the liquid level is not to be observed.

6. Microstructure Structure of Crack Repair

A scanning electron microscope (SEM) is a device that scans a thin electron beam onto a sample surface to generate secondary electrons to obtain a three-dimensional surface of a sample. The scanning electron microscope used in this experiment was the Philips XL30 ESEM.

Experimental Results and Discussion

1. Mechanical Properties and Microstructure Analysis

1) Attachment strength in standard condition

In the present invention, the composition for repairing concrete cracks is a means for preventing the performance degradation of concrete due to CO2 gas, chloride and fine cracks penetrating from the outside by forming a protective film using a brush or spray treatment agent on the concrete surface. Therefore, the most basic thing for evaluating performance is how strongly the crack repair material (or crack repair composition) adheres to the existing concrete sphere for a long time. In order to evaluate the adhesion performance of the crack repair composition according to the invention and the crack repair material (or crack repair composition) as a control in the experiment summarized the results of the adhesion strength is shown in Figure 2 summarized.

As can be seen from these results, it was found that the adhesion strength increased as the age of all specimens increased, and the adhesion strength of all four types exceeded 1 MPa specified in KS F 4936, indicating that the adhesion performance was excellent. there was.

At this time, S4 according to the present invention showed the best adhesion performance, in the case of S4 showed a shape that the mother is destroyed by the integral coupling with the mother at all ages, in the case of S1, S2 and S3 age 7 days It was confirmed that dropout occurred at the interface with the parent at. This suggests that S4 has a good bond with the concrete matrix. However, in all crack repair materials (or crack repair compositions), it was confirmed that the mother was destroyed in the fallout shape at the age of 28 days.

In the case of S4, in which the maternal drop-out shape occurred at the same age and the highest adhesion strength in the same binder, the nanopolymer binder (i.e., liquid nano acrylic emulsion) and nano ceramic (i.e., liquid nano silicate) contained in S4 were used. By penetrating into the pores of the surface to have an integrated structure, it is judged that the adhesion force is improved to show the mother dropout shape.

2) Adhesion strength in wet and dry condition

In order to evaluate the adhesion performance of the crack repair material (or crack repair composition) under the harsh conditions of wet and dry repetition, immersion test was performed for 2 days and then dried for 1 cycle. 3 is shown.

As can be seen from these figures, the magnitude of adhesion strength in the wet and dry state was found in the order S4> S3> S2> S1. In addition, it was found that the adhesion strength of the four types of crack repair materials (or crack repair compositions) exceeded all of 1 MPa specified in KS F 4936, so that the adhesion performance was excellent.

In the case of coating materials, the adhesion strength due to wet and dry repetition is generally reduced, but in the case of the crack repair material (or crack repair composition) used in this experiment, 15 cycles of wet and dry condition compared to the 28-day adhesion strength in the standard state The bond strength of was rather larger. This is thought to be due to the hydration reaction of the crack repair material (or the composition for crack repair), resulting in a more densely formed tissue structure resulting in increased adhesion strength.

In addition, S4 showed the largest bond strength value among the four types of crack repair materials (or crack repair compositions) even in the dry and dry repetitive conditions, similar to the results of the standard bond strength.

3) Microstructure Analysis

In order to examine the structure and elemental analysis according to the application of crack repair composition, the crack repair composition according to the present invention was applied to the test specimen cured for 28 days or more. 4 is shown.

As can be seen from this result, it was observed that Ca (OH) 2 and Type-III CSH were distributed in a large amount in the crack repair composition according to the present invention, which was investigated by EDS profile. In addition, it was confirmed that Ca and Si were distributed in a large amount.

In addition, it can be seen that the structure is very dense than the general concrete. In this case, since a dense structure is formed by the composition for crack repair, penetration of harmful substances such as chlorine ions and carbon dioxide into the pores is prevented from being penetrated, and thus, it is judged that the resistance to concrete performance is excellent.

2. Evaluation of durability

1) Resistance to chlorine ion penetration

5 and 6 show the results of measurement of the chlorine ion diffusion coefficient by the total amount of charge and the penetration depth in order to evaluate the resistance to salt permeation diffusion of the crack repair material (or the composition for crack repair).

As can be seen from these results, in the case of general concrete (weakly referred to as NC), the total passing charge was 2058 (Coulomb), and according to the chlorine ion permeability evaluation criteria of <Table 2>, it showed a moderate state. In the test body to which the repair composition) was applied, the results were Low and Very low. In addition, the test body coated with the crack repair material (or crack repair composition) was found to be reduced by 48 to 69% compared to the NC. Especially, in the case of S4, which is a crack repair composition according to the present invention, the total amount of passing charge was 992 ( Coulomb) was found to have a reduction of about 48% compared to NC.

On the other hand, in the diffusion coefficient results of the penetration depth of the chlorine ion of Figure 6 in the case of NC is 6.56E-12, while the diffusion coefficient ratio is about 54 ~ 78% in the test specimen coated with crack repair material (or crack repair composition) It showed a tendency to decrease. Particularly, in the case of S4, the composition for crack repair according to the present invention, 3.57E-12 was found to decrease by about 54%. Similar to the result of the adhesion strength, in the case of S4, the nanopolymer binder and the nano ceramic penetrate into the pores of the mother surface, filling the pores by the micro-filler effect to form a dense tissue structure, thereby forming harmful ions. It is thought that the resistance to chlorine ion penetration is improved by blocking.

2) resistance to carbonation

The concentration of carbon dioxide in the atmosphere is about 0.03%, which takes a lot of measurement time when carbonation experiments are performed in nature. Therefore, the method of estimating the carbonation depth experimentally in the accelerated experimental apparatus to increase the carbon dioxide concentration to predict the carbonation depth at long-term age is mainly used.

In the present invention, the carbonation test was carried out using the accelerated carbonation test apparatus, and the measurement for the accelerated test of the test body coated with the concrete protective crack repair material (or crack repair composition) was carried out for 14 days and 28 days, and after the test body was split, the split surface was determined. The result of having measured the depth of the uncolored part as a carbonation part by spraying a 1% phenolphthalein solution to the object was put together in FIG.

As can be seen from these results, the carbonation depth showed the deepest carbonation depth in the case of Test NC which was not coated with crack repair material (or crack repair composition) at 14 days of accelerated age. On the other hand, the neutralization depth of the test specimen coated with the crack repair material (or crack repair composition) tended to decrease by 30-50% compared to the NC. The carbonation depth of 28 days of promotion age was different from that of S1 and S2, whereas the carbonation depth of S1 and S2 was larger than that of NC test specimens, whereas the carbonation depth of S3 and S4 decreased by 80%. In this regard, the control groups S1, S2 and S3 do not contain a nanopolymer (ie liquid nano acrylic emulsion) binder, and S4 according to the present invention is a nanopolymer (ie liquid nano acrylic emulsion) binder and a nano ceramic. (Ie, liquid nanosilicates) are added in combination to penetrate into the fine capillary pores of concrete similarly to the chlorine ion diffusion characteristics, so that the pores of the concrete are changed more densely and the carbonation resistance is improved.

3) salt water resistance

For the saline resistance test, the specimen was immersed at room temperature for 20 days using 3% NaCl solution for 15 days, and the specimen was taken out and washed with clean water and left for about 2 hours. Was visually observed. Results for saline resistance are shown in Table 4 and FIG. 8.

As can be seen from these results, all specimens coated with crack repair material (or crack repair composition) showed good resistance to salt water resistance such as swelling, peeling, softening, lifesaving, and color change, but weak in the control group S1 and S2. Softening phenomenon appeared. In addition, although all kinds of crack repair materials (or crack repair compositions) exhibited excellent resistance to salt water resistance, it is expected that more various chemicals and the need for long-term testing will be required.

As described above, as a result of evaluating the mechanical properties of the crack repair material (or crack repair composition), all specimens in the standard state and the wet and dry state showed excellent adhesion performance exceeding 1 MPa specified in KS F 4936. As a result of evaluating the resistance to diffusion, the specimens coated with crack repair material (or crack repair composition) showed Low and Very low, and the diffusion coefficient by chlorine ion penetration depth was about 54 ~ 78% compared to general concrete. There was a decreasing effect. In this regard, in the case of the composition for crack repair according to the present invention (S4 in the evaluation results), it can be seen that the overall excellent properties compared to S1 to S3.

In addition, the neutralization depth of the crack repair composition according to the present invention was measured after the neutralization depth test. As a result, the neutralization resistance was much better than that of the general concrete. A large amount of Ca (OH) 2 and Type-III CSH were observed, and the salt water resistance test resulted in swelling, peeling, softening, and swelling in all specimens coated with crack repair material (or crack repair composition). There was an effect showing good resistance to salt water resistance such as lifesaving and color change.

The present invention having the configurations and effects described above can be modified in various ways, and the above description is not intended to limit the scope of the present invention. In addition, various modifications and variations are possible without departing from the spirit and scope of the invention, and modifications apparent to those skilled in the art to which the invention pertains are included within the scope of the following claims.

1 is a photograph showing a process of measuring the adhesion strength of the crack repair material (or crack repair composition) in the experimental example of the present invention.

Figure 2 is a graph showing the results of relatively evaluating the adhesion strength of the standard state of the crack repair material (or crack repair composition) in the experimental example of the present invention.

Figure 3 is a graph showing the results of relatively evaluating the adhesion strength of the wet and dry repetitive state of the crack repair material (or crack repair composition) in the experimental example of the present invention.

Figure 4 is a photograph showing the SEM & EDS analysis of the crack repair composition according to the present invention.

Figure 5 is a graph showing the results of evaluating the total pass charge of the crack repair material (or crack repair composition) in the experimental example of the present invention.

Figure 6 is a graph showing the chlorine ion penetration depth and diffusion coefficient of the crack repair material (or crack repair composition) in the experimental example of the present invention.

7 is a graph showing the carbonation depth of the crack repair material (or crack repair composition) in the experimental example of the present invention.

8 is a photograph showing the specimen after the salt water resistance test of the crack repair material (or crack repair composition) in the experimental example of the present invention.

Claims (2)

A crack repair composition for coating a surface of a concrete structure to form a protective film, comprising: (i) a powdered inorganic crack repair material having a specific gravity of 1.62 as a binder; (ii) a liquid nano silicate having a specific gravity of 1.01 and a solid content of 2.5% by weight; (iii) by addition of a combination of a liquid nano acrylic emulsion having a specific gravity of 1.02 and a solids content of 50% by weight, The composition for crack repair, characterized in that the concrete structure coated with the composition exhibits the following characteristics: Adhesion strength of 28 days of age under standard condition according to KS F4936 is 2.8 MPa, Total charge of chlorine ion is 992 coulomb, reduced to 48% when the composition is not applied, The diffusion coefficient by the depth of penetration of chlorine ions is 3.57E-12, reduced to 54% when the composition is not applied. delete