KR20090005853A - The nano mixed non-organic repair material for crack repair of concrete structure - Google Patents

Abstract

A nano mixed inorganic repair material is provided to ensure excellent adhesion performancel, good salinity penetration, neutralization and salt water resistance and to recover and improve the performance of a concrete structure. A nano mixed inorganic repair material used for crack repair of a concrete structure comprises (1) powdery crack repair material containing an inorganic material as a main material, (2) liquid nanosilicate containing silicate as a main material,; and (3) liquid nano polymer binder containing nano acryl emulsion as a main material.

Description

Nano Synthetic Inorganic Repair Materials for Crack Repair of Concrete Structures {THE NANO MIXED NON-ORGANIC REPAIR MATERIAL FOR CRACK REPAIR OF CONCRETE STRUCTURE}

1 is a photograph of the process of measuring the adhesion strength of the nano-synthetic inorganic repair material according to the present invention.

Figure 2 is a graph showing the adhesion strength of the standard state of the nano-synthetic inorganic repair material according to the present invention.

Figure 3 is a graph showing the adhesion strength of the wet and dry repeat state of the nano-synthetic inorganic water-retaining material according to the present invention.

Figure 4 is a photograph showing the SEM & EDS analysis results of the nano synthetic inorganic repair material according to the present invention.

5 is a graph showing the total amount of charge passing through the nano-synthetic inorganic water-retaining material according to the present invention.

Figure 6 is a graph showing the depth of chlorine ion penetration and diffusion coefficient of the inorganic nano-repairing material according to the present invention.

7 is a graph showing the carbonation depth of the nano-synthetic inorganic repair material according to the present invention.

Figure 8 is a photograph showing the specimen after the salt water resistance test of the nano-synthetic inorganic repair material according to the present invention.

The present invention relates to an economical and eco-friendly nano-synthetic inorganic crack repair material incorporating cutting-edge technology for the performance recovery and performance improvement of the concrete structure cracked.

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 in concrete structures severely degrade the performance of concrete, and further shorten their 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 economic and eco-friendly nano-synthetic inorganic-based crack repair materials incorporating advanced technology and utilizing them in the construction industry, ultimately Is to contribute to industrial development.

In order to solve the above problems, the present invention is a repair material used for crack repair of concrete structures, the repair material is a powder-type crack repair material whose main component is inorganic, liquid nano silicate whose main component is silicate, and the main component This nanoacrylic emulsion provides a nano-synthetic inorganic crack repair material comprising a liquid nano polymer binder, furthermore, the powder crack repair material has a specific gravity of 1.62, the nano silicate has a specific gravity of 1.01 and a solid content of 2.5%, The nanopolymer binder has a specific gravity of 1.02 and provides a nano-synthetic inorganic crack repair material, characterized in that the solid content is 50%.

Hereinafter, with reference to the accompanying drawings and diagrams, the experiment on the mechanical properties and durability of the nano-synthetic inorganic crack repair material 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. Nano synthetic inorganic crack repair material

The crack repair material according to the present invention is an inorganic crack repair material, and used nanosilicates and nano polymer binders to improve adhesion with the base concrete. The main components and physical properties of the crack repair material are shown in Table 1 below.

4. Test body production

The water-cement ratio of the ground concrete used to apply the crack repair material 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. After applying the crack repair material 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.

Experiment method

1. Evaluation of adhesion performance in standard condition

After applying the crack repair material to the surface of the test body, as shown in Fig. 1 (a) put the top of the steel jig, and after bonding to remove the 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 performance degradation of the test specimen, the wet and dry repeated strength test was performed by immersion test using 1 cycle of making a frame on the specimen surface, immersing in solution for 2 days, and drying for 2 days. The test was conducted by the method.

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.

(식 1)

(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.

(식 2)

(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, and holes were visually observed and the change of color 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

Concrete crack repair material is a means to prevent 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 way to evaluate the performance of crack repair material is how strongly the crack repair material adheres to existing concrete spheres. In order to evaluate the adhesion performance of the crack repair material used in this experiment, the results of measuring the adhesion strength are summarized in FIG. 2.

As can be seen from these results, it was found that the bond strength increased as the age of all specimens increased, and the adhesion strength of four types of crack repair materials exceeded 1MPa specified in KS F 4936, which is excellent in adhesion performance. Could know.

In addition, in the case of S4, which showed the best adhesion performance among the crack repair materials, the mother was destroyed by the integral bonding with the mother at all ages, but in the case of S1, S2 and S3, the interface with the mother at 7 days of age. It was confirmed that the dropout occurred at. This suggests that S4 has a good bond with the concrete matrix. However, in all crack repair materials, it was confirmed that the mother was destroyed in the dropout shape at 28 days of age.

In the case of S4 where the maternal dropout shape occurs at the same age and the bond strength is the highest in the same binder, the nanopolymer binder and nano ceramics contained in S4 penetrate into the pores of the mother surface to have an integrated structure. It is judged that the mother dropout shape is shown by the improvement.

2) Adhesion strength in wet and dry condition

In order to evaluate the adhesion performance of the crack repair material under the harsh conditions according to the wet and dry repeat, the results up to 15 cycles are shown in FIG.

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 exceeded 1 MPa specified in KS F 4936, so that the adhesion performance was excellent.

In the case of coating material, it is common to reduce the adhesion strength due to wet and dry repetition, but in the case of crack repair material used in this study, the adhesion strength in the dry and repeated 15 cycles was 15 times higher than that of standard 28 days. appear. This is thought to be due to the formation of more dense structure due to the hydration reaction of the crack repair material, resulting in increased adhesion strength.

In addition, S4 showed the highest bond strength value among the four types of crack repair materials in the wet and repeated condition similar to the bond strength results of the standard state.

3) Microstructure Analysis

In order to examine the structure and elemental analysis of the crack repair material in the present invention, the results obtained through SEM and EDS imaging after 7 days or more after the application of each crack repair material to the specimen cured for 28 days or more is shown in FIG. .

As can be seen from these results, it was observed that Ca (OH) 2 and Type-III CSH were distributed in a large amount in the nano-composite inorganic crack repair material. It was confirmed that Si was 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 the crack repair material constitutes a dense structure, the degradation performance of harmful components such as chlorine ions and carbon dioxide is prevented from penetrating into the crack repair material, so that the performance of the concrete is excellent.

2. Evaluation of durability

1) Resistance to chlorine ion penetration

5 to 6 show the results of measuring the chlorine ion diffusion coefficient according to the total charge amount and penetration depth in order to evaluate the resistance to salt penetration of the crack repair material.

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 the chlorine ion permeability evaluation criteria of <Table 2> showed a moderate state. The specimens showed Low and Very low. In addition, the test specimen coated with crack repair material showed a 48 ~ 69% reduction in comparison with NC. Especially, in case of S4, total charge passed through 992 (Coulomb) was found to be reduced by 48% compared to NC. It became.

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 was 6.56E-12, while in the test specimen coated with crack repair material, the diffusion coefficient ratio tended to decrease to about 54 ~ 78% level. In particular, in case of S4, 3.57E-12 decreased 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 an accelerated carbonation test apparatus to measure the accelerated test of the test body coated with the concrete protection crack repair material for 14 days and 28 days, and after splitting the test object, 1% of phenolphthalein was used for the splitting surface. The result of having measured the depth by spraying a solution and making an uncolored part into a carbonation part is shown collectively in FIG.

As can be seen from these results, the carbonation depth showed the deepest carbonation depth in the specimen NC without crack repairing material at 14 days of acceleration age. On the other hand, the neutralization depth of the specimen coated with crack repair material showed a tendency to decrease by 30 ~ 50% compared to 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, while that of S3 and S4 decreased by 80%. These results indicate that S1, S2, and S3 are repair materials for cracks that do not contain nano-nanopolymer binders, and S4, which contains nanopolymer binders and nano ceramics, is similar to the chlorine ion diffusion characteristics. It is believed that the concrete pores change more densely and penetrate into the pores, thereby improving the carbonation resistance phase.

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 showed good resistance to saline resistance such as swelling, peeling, softening, life saving, and color change, but weak softening phenomenon in S1 and S2. In addition, although all kinds of crack repair materials exhibited excellent resistance to salt water resistance, it is expected that more various chemicals and the need for long-term tests will be required.

As described above, as a result of evaluating the mechanical properties of the nano-composite inorganic crack repair material according to the present invention showed excellent adhesion performance exceeding 1MPa specified in KS F 4936 in all the specimens of the standard state and dry and repeated conditions, salt penetration As a result of evaluating the resistance to diffusion, the specimens coated with crack repair material showed Low and Very low, and the diffusion coefficient by chlorine ion penetration depth was reduced to about 54 ~ 78% compared to general concrete.

In addition, as a result of measuring the neutralization depth of the nano-synthetic inorganic crack repair material of the present invention after the neutralization promotion test, the neutralization resistance was very good compared to the general concrete, and the structure and elemental analysis of the crack repair material, The distribution of Ca (OH) 2 and Type-III CSH on the hexagonal plate was observed to be large, and the salt water resistance test resulted in swelling, peeling, softening, lifesaving, and color change in all specimens coated with crack repair material. There was an effect of showing good resistance to salt water resistance such as.

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.

Claims (2)

In the repair material used for crack repair of concrete structures, the repair material A nano-composite inorganic crack repair material comprising an inorganic powder crack repair material having a main component, a liquid nano silicate whose main component is a silicate, and a liquid nano polymer binder whose main component is a nanoacrylic emulsion. The method of claim 1, wherein the powder crack repair material has a specific gravity of 1.62, the nano silicate has a specific gravity of 1.01, solid content of 2.5%, the nanopolymer binder is characterized by a specific gravity of 1.02, characterized in that the solid content is 50%. Nano synthetic inorganic crack repair material.

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