JP2009274942A - Water-soluble concrete repairing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repairing agent which is used for repairing concrete by injection or filling into a crack of the concrete and further for modifying the surface of the concrete; and to provide a construction method for repairing concrete. <P>SOLUTION: In order to repair a crack in mortar or concrete, an aqueous silicic acid solution is injected into the crack to combine silicic acid with a base material at the depth of a crack and to develop strength. Alternatively, a cement paste obtained by kneading cement with the aqueous silicic acid solution is injected into an inner part of a crack. The surface modifying method comprises sticking, applying or blowing the paste or mortar on a surface. Further, a repairing agent composed of an aqueous silicic acid solution whose pH can be varied and the construction method for repairing concrete are also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a drug for repairing cracks, cracks and the like of mortars and concrete structures. Further, it is a modification technique characterized by surface modification of deteriorated mortar and concrete, as well as an injection agent and filler for cracks and cracks.
In both cases, when applying surface construction and surface makeup, it is indispensable as a repair technique to maintain the cracks and cracks deeply. Therefore, it is a technique related to a repairing agent that injects a water-soluble repairing agent up to the deep part of the crack, combines with the material inside the mortar and concrete to develop strength, and reinforces the matrix. At the same time, it is a technique related to surface modification by injecting, applying or spraying cement paste and mortar mixed with this water-soluble repair agent into cement.

Current situation

  Mortar and concrete repair technology must be repaired by filling the cracks and cracks with chemicals, but many of these are filled with epoxy resin or clay minerals, or water glass-based silicic acid. It is similar to a sodium solution. Water glass-based ones have increased functionality by mixing lithium salts.

  Many of these fillers and modifiers provided on the market are gel-like or liquid. It is in the form of gel such as resin or clay mineral, or sodium silicate liquid. Although the functionality is enhanced by diluting the concentration with a volatile organic compound or mixing a lithium salt, the viscosity of the gel or liquid is high even if injected, and it is difficult to infiltrate. At most, it is only a few millimeters from the entrance. Most of them can only penetrate several millimeters near the surface. Therefore, it must be considered that the deep part of the crack is hollow.

  Epoxy resins and the like, which are resin-based repair materials, are hardly deteriorated by ultraviolet rays even when applied to the concrete surface, and are not durable because they are not durable. It has been pointed out that carbonation proceeds due to changes with time due to moisture such as rainwater and carbon dioxide in the atmosphere, and the surface layer part peels off.

  In addition, the sodium silicate repair agent, which is the main component of the water glass system, is considered to cause the sodium content to react with the aggregate of the concrete when injected, and abnormally swell to destroy the tissue. . This is an alkali-aggregate reaction and is a phenomenon that appears prominently over time.

  In order to suppress such an alkali-aggregate reaction, it is a reality that low alkaline cement is recommended as a cement constituting the concrete. Considering this, it is a big problem to use a water glass-based solution containing a high concentration of sodium as a repair agent. It causes expansion again, and fine cracks are generated, making it meaningless to repair at all.

Problems to be solved by the invention

  The present invention is that a repair agent can be injected into fine cracks and cracks generated on the concrete surface. That is, it has the same viscosity as that of an aqueous solution and can be injected into a deep part of a fine crack. Furthermore, after injection, it is also bonded to the material inside the crack, so that calcium silicate hydrate can be produced. In addition, the material inside the crack that has already been carbonated is calcium carbonate, and part of it is calcium hydroxide. This is dissolved in silicic acid to form calcium ions, which are combined with the injected repair agent and combined with calcium silicate. -To be able to produce hydrates.

  The injection agent according to this application has an extremely reduced sodium content, thereby suppressing alkali-aggregate reaction and making it possible to repair concrete cracks and cracks. Also, the viscosity of the solution is the same as that of water, and the solution can be injected up to the depth of the crack. By this injection, the material reacts with the material inside the crack over time, and the development of strength can be expected.

Means for solving the problem

Water-soluble silicic acid was synthesized as an agent for repairing concrete cracks. Although it is difficult to specify the chemical formula, it is mainly represented by H ₄ SiO ₄ or H ₆ Si ₂ O ₇ . This contains a small amount of sodium, and the pH of the solution can be varied depending on the purpose. The pH is preferably 2.0 to 6.0 on the acidic side, and more preferably 2.5 to 5.5 when used on the acidic side. When using it by alkalinity, 8.0-13.5, especially 8.2-12.5 are desirable. The viscosity is 2.0 mPa · S at 25 ° C., almost the same as water.

  The internal structure of the concrete crack is chemically calcium carbonate and partially calcium hydroxide, which are present on the concrete surface. The cause of the occurrence of these minerals is that they are carbonated because they are affected by carbon dioxide over a long period of time. By injecting an acidic aqueous silicic acid solution, calcium carbonate is dissolved with silicic acid to form calcium ions. When alkaline silicic acid is injected under these conditions, calcium silicate hydrate is formed and functions to fill the internal structure.

When calcium hydroxide or calcium carbonate, which is the material inside the crack of the concrete, is mixed with water-soluble silicic acid, a cured product can be produced. As an example, when a silicic acid aqueous solution with a pH of 9.0 is used, and when a silicic acid aqueous solution with a pH of 3.0 is used, photographs taken for 7 days in a thermostatic container at 25 ° C. are shown in FIGS. As shown in FIG. These hardened bodies were confirmed to develop compressive strength depending on the age. FIG. 4 shows the compressive strength of each product at the age of 3 days, 7 days, 28 days, and 3 months.

した後、２１日間気中養生（２０℃、６０％ＲＨ）したものを供試体とした。養生終了後、絶乾状態とし、水とケイ酸水溶液の液槽に供試体を含浸した。

含浸深さ試験の結果を表２に示す。また、吸水率試験の結果を表３に示す。実施例ではケイ酸水溶液が実際に浸透していく過程の写真を図５（１時間）、図６（３時間）に示す。これらの結果より、ケイ酸水溶液は水と同様に浸透していくことが判明した。A method is used in which a liquid is filled in the injector and injected into a cracked portion of the concrete, or is injected with a high-pressure injector. Further, an impregnation depth test and a water absorption rate test were conducted when the aqueous silicic acid solution was poured into the concrete.
Test Method According to JIS R 5201 (cement physical test method), mortars prepared as shown in Table 1 were mixed by adjusting the water cement ratio so that the flow value was 180 ± 5 mm. That morta

After that, what was subjected to air curing (20 ° C., 60% RH) for 21 days was used as a specimen. After curing, the sample was completely dried, and the specimen was impregnated in a liquid bath of water and an aqueous silicic acid solution.

The results of the impregnation depth test are shown in Table 2. Table 3 shows the results of the water absorption rate test. In the examples, photographs of the process in which the aqueous silicic acid solution actually permeates are shown in FIG. 5 (1 hour) and FIG. 6 (3 hours). From these results, it was found that the aqueous silicic acid solution penetrated in the same manner as water.

The invention's effect

  The present invention is intended to provide a material excellent in solution system permeability for repairing cracks (small cracks, cracks) in concrete. Conventionally, epoxy resin or the like has been infiltrated into the crack, but this is affixed to the surface layer portion, and since it cannot be filled up to the deep part of the crack, it cannot be said that it is essentially repaired. In addition, the deterioration due to ultraviolet rays is severe, and it is not a method with high durability. On the other hand, the water glass-based repair material has high gel viscosity and cannot be filled to the depth of the crack. The present invention is a repairable intelligent material that automatically develops strength when it is combined with the material of the concrete itself using an aqueous silicic acid solution. Filling a fine gap reaching the deep part of the crack causes strength development, and the matrix can be repaired.

  Fine cracks should be injected with an aqueous silicic acid solution, or cement cracks kneaded with an aqueous silicic acid solution should be injected for large cracks. Alternatively, the repair surface must be decorated by a cement paste kneaded with an aqueous silicic acid solution, or by a method such as affixing, applying, or spraying with a mortar.

Claims (5)

When the concentration of silicon in the aqueous silicic acid solution is varied and the pH of the solution is used in an acidic state, the pH is 2.0 to 6.0, and when used on the acidic side, the pH is preferably 2.5 to 5.5. When the concentration of sodium in the aqueous silicic acid solution is changed and the pH of the solution is used in an alkaline state, the pH is 8.0 to 13.5, and in particular when it is used in an alkaline state, 8.2 to 12.5 is preferable. A method of increasing strength by injecting an aqueous solution of silicic acid into cracks, cracks and cracks in concrete and bonding it to the material deep in the cracks. A method of injecting cement paste kneaded with silicic acid aqueous solution after injecting silicic acid aqueous solution into the crack. A method of surface modification by cement paste kneaded with silicic acid aqueous solution or mortar, pasting, applying, spraying, etc.

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