WO2020003430A1

WO2020003430A1 - Concrete repairing method and repairing agent

Info

Publication number: WO2020003430A1
Application number: PCT/JP2018/024530
Authority: WO
Inventors: 豊富田
Original assignee: 日本プロロング株式会社
Priority date: 2018-06-28
Filing date: 2018-06-28
Publication date: 2020-01-02
Also published as: WO2020004434A1; PH12020552131A1; JPWO2020004434A1; CN112469876A

Abstract

Provided is a repairing method that enables filling a crack with gel so as to provide adequate water proofing properties and adequate water sealing properties even in the case where the width of the crack is equal to or greater than a certain width. The method comprises: a first step for injecting, spraying, or applying a silicate-containing solution to a concrete surface having a crack; a second step for performing filling by injecting or applying an inorganic material fluidized by addition of water, into the crack having the concrete surface moistened with the silicate-containing solution; and a third step for spraying or applying a silicate-containing solution to the concrete surface in which the crack has been filled with the inorganic material.

Description

Repair method and repair agent for concrete

The present invention relates to a method and a repair agent for repairing concrete, and more particularly, to a method and a repair agent for repairing cracks formed in concrete.

The surface of concrete is exposed to various environments such as drying, solar radiation, temperature change, humidity change, exposure to rain and carbon dioxide, and frost damage. It is important to protect concrete from these factors and prevent concrete deterioration to extend the life. However, it is difficult to actually make concrete without cracks.

Therefore, it is generally specified in the design and construction of architectural and civil engineering structures that concrete structures are allowed to have a certain crack width and appropriate measures are taken for crack widths exceeding the crack width. The crack width is 0.3 mm for a general building structure, and 0.2 mm for a general civil engineering structure.

Conventionally, as a method of repairing such cracks in concrete, a method of applying an alkali metal silicate aqueous solution, penetrating the cracks, reacting with components in the concrete to form a gel, and filling the cracks with the gel. (For example, see Patent Documents 1 to 5).

JP 2003-212674 A JP 2004-323333 A JP 2005-239523 A JP 2010-070403 A Japanese Patent No. 5504414

場合 However, when the crack width is larger than a certain width, the silicate aqueous solution cannot be held in the crack until a gel is formed, so that there is a problem that the filling of the crack by the gel cannot be expected.

In view of the above problems, the present invention is a method for repairing concrete,
A first step of injecting, spraying or applying a solution containing silicate to the surface of the cracked concrete;
A second step of injecting or applying and filling an inorganic material fluidized by water into a crack having a surface of concrete wet with a solution containing silicate;
Spraying or applying a solution containing silicate to the surface of the concrete after the inorganic material has been filled in the cracks.

According to the present invention, even if the crack width is equal to or greater than a certain width, the crack can be filled with the gel, and sufficient waterproofness and water stoppage can be imparted.

The flowchart which showed the flow of the operation | work which repairs the crack formed in the concrete. The figure explaining the state in which the crack occurred in concrete. The conceptual diagram which shows a mode that each solution penetrates into a crack. Surface illustrating a transparent container containing two concrete blocks. The figure which illustrated the place where two concrete blocks were stored in the container, and the circumference was sealed with caulking material. The figure which illustrated the place where the gap between two concrete blocks was closed. The figure which illustrated the place where water was put on the upper part of two concrete blocks which closed the gap.

Concrete is prepared by putting cement, aggregate, water, and admixture into a mixer, mixing, kneading, assembling a formwork, placing it in a formwork, curing it so that setting proceeds properly, and removing it from the mold. It is manufactured in a desired shape.

Cement is a powder that contains clinker generated by mixing limestone, clay, and the like and firing, and gypsum, and is a powder that hardens by a hydration reaction, polymerization, or the like. The aggregate is made of gravel, sand, or the like, and reduces the proportion of cement, thereby suppressing heat generation due to the hydration reaction of the cement and shrinkage due to evaporation of moisture. The admixture is an agent added for the purpose of improving strength and durability, adjusting the setting speed, and the like.

(5) Curing is the work of controlling the temperature and moisture content until the concrete is sufficiently hardened. In the curing operation, the concrete is covered with a blue sheet or the like, the temperature is kept at an appropriate temperature by a heater or the like, and water content is kept at a specified level by water sprinkling or the like.

Concrete contains excess water, and due to drying shrinkage, temperature change, humidity change, exposure to rain and carbon dioxide, and frost damage caused by evaporation of the excess water, as well as external factors such as building weight and seismic force. Under load, cracks occur.

Concrete cracking is acceptable if it has a certain width. On the other hand, it is required to take appropriate measures for a crack width exceeding this. Cracks requiring treatment include small cracks having a width of less than 0.2 mm and large cracks having a width of 0.2 mm or more. A method for repairing both will be described with reference to FIG.

FIG. 1 is a flowchart showing a flow of work for repairing cracks formed in concrete. The operation starts from step 100, and in step 101, the surface of the concrete surface is cleaned or the like so that the solution for repair is easily injected. The cleaning of the base is performed by using a brush, high-pressure water such as fresh water, a wire brush, or the like to remove dust and the like.

Due to the above factors, cracks 11 are formed in the concrete 10 as shown in FIG. FIG. 2A is a diagram exemplifying a crack visible in appearance, and FIG. 2B is an enlarged view of a cross section cut along a cutting line AA. When the crack 11 is formed, rainwater, carbon dioxide, and the like enter the concrete 10 through the crack 11 to deteriorate the concrete 10 and rust the internal rebar, thereby lowering the durability. Repairs are performed to close the cracks.

In step 102, the width of cracks on the concrete surface is measured. The crack width is the width of the crack shown in FIG. 2 (b). A crack scale (ruler) or a system that calculates the width by capturing the crack with a camera and analyzing the captured image is used as a measuring instrument. Can be measured. The width of the crack is related to the size of the crack. As the crack width increases, rainwater and the like easily penetrate, and the strength of the concrete decreases.

In step 103, it is checked whether the crack width is 0.2 mm or more. If it is 0.2 mm or more, proceed to step 104, and if it is less than 0.2 mm, proceed to step 124. In step 104, it is checked whether the crack width is 0.3 mm or more. Here, the determination is made based on the two crack widths of 0.2 mm and 0.3 mm, but is not limited to 0.2 mm and 0.3 mm, and an appropriate width can be set as appropriate.

If the crack width is 0.3 mm or more, proceed to step 105 and use a grinding device such as a disc grinder to form a groove with a U-shaped or V-shaped cross section along the crack. In this case, since the crack is large and the crack easily spreads, in order to enhance the reinforcing effect, such a groove is formed, and a U-cut seal filling method for increasing the bonding area is also used.

After cleaning the inside of the groove with high-pressure water or a wire brush using clean water, the process proceeds to step 106, where water is sprayed for deep penetration. In step 107, a solution containing silicate (hereinafter, referred to as a silicate solution) ) Is injected, sprayed or applied to wet the cracked surface. By making the wet state as described above, the concrete near the inner surface of the crack is reformed, and the inorganic material is integrated with the concrete when the crack is later filled with the inorganic material.

(4) The silicate solution is, for example, an alkali silicate aqueous solution prepared by mixing at least two of sodium silicate, potassium silicate, and lithium silicate and adding an appropriate amount of water. The aqueous alkali silicate solution is a solution having a pH of 11 to 12, a small particle size of silicate of about 1 to 10 nm, and a low viscosity of 6 to 8 (mPa · s).

２The reason why two or more of these silicates are blended is that hardness and density are increased and chemical durability is improved as compared with the case of a single silicate. When at least two of sodium silicate, potassium silicate and lithium silicate are mixed, the mixing ratio when mixing the two can be in the range of 1: 9 to 9: 1 in molar ratio, and can be 3: 7 to 7: 1. It is desirable to set it within the range of 7: 3. When the three are mixed, the mixing ratio of sodium silicate can be 5 to 90 mol%, potassium silicate can be 5 to 90 mol%, lithium silicate can be 5 to 90 mol%, and sodium silicate can be 15 to 70 mol%. %, Potassium silicate is preferably 15 to 70 mol%, and lithium silicate is preferably 15 to 70 mol%.

水 The amount of water added to the silicate may be any amount as long as the silicate can be dispersed.

方法 Examples of the method of applying the silicate solution include brushing, roll coating, spray coating and the like. Examples of a method for spraying the silicate solution include a method using a spray. When using a spray, the nozzle can be brought into close contact with the cracks to attempt deep penetration. As a method for injecting the silicate solution, a method using an oil jug can be exemplified.

(4) The crack 11 after the application of the silicate solution or the like is, for example, as shown in FIG. Referring to FIG. 3A, the silicate solution penetrates by about several mm from the concrete surface inside the crack to form the modified portion 13, and the exposed surface in the crack 11 is covered with the silicate solution 12. It is in a wet state.

場合 If the concrete slab to be repaired is a deck slab and cracks have penetrated, use a greaser or the like to inject the silicate solution with sufficient intention to retain the silicate solution at the bottom.

(4) After applying the silicate solution or the like, in Step 108, water is sprinkled on the entire construction surface to be kept wet.

(4) After being placed in a wet state in this way, the process proceeds to step 109, at which the inorganic material fluidized by water is injected or applied as an aqueous filler. This is because the crack is filled to some extent by an inorganic material having a relatively large particle diameter.

セメント As the inorganic material, for example, cement can be used. Note that generally used cement particles are preferably fine particles because of their large particle size. The cement is fluidized into a cement slurry, which can be injected by a hand-operated mortar pump. Further, an admixture may be added as needed to improve fluidization.

Portland cement can be used as the cement, but is not limited thereto, and may be blast furnace cement, silica cement, fly ash cement, or the like. Blast furnace cement is a cement in which fine powder of blast furnace slag and Portland cement are mixed. Silica cement is a cement in which a natural siliceous mixture containing 60% or more of silica and Portland cement are mixed. Fly ash cement is a cement in which coal incineration ash (fly ash) and Portland cement are mixed.

The injection of the cement slurry can be started with a low-concentration slurry, and with a high-concentration slurry having a water-cement ratio of 60 to 80% while changing the composition.

The crack 11 after filling in step 109 is as shown in FIG. That is, a certain portion of the crack 11 is filled with the cement 14. The reason is that the cement fluidized by the addition of water has a larger particle diameter and a higher viscosity than the silicate solution, and therefore does not immediately flow downward unlike the silicate solution.

充填 The crack filling in this method uses an inorganic material such as cement, and does not use an organic material such as an epoxy resin or an acrylic resin, so that the deterioration of the material over time can be eliminated. Further, by using together with the silicate solution, it is possible to prevent hardening or shrinkage phenomenon from appearing in the injected cement grout, peeling off from the concrete on the cracked surface, and generating new cracks.

方法 The method of applying the fluidized inorganic material includes brushing, roll coating, spray coating, and the like, as in the method of applying the silicate solution. In the method of injecting the fluidized inorganic material, a hand-pressed mortar pump can be used.

The cement 14 reacts with water in the filled cracks 11, polymerizes and hardens, and integrates with the concrete 10. With this alone, it is not possible to follow the subsequent shrinkage due to drying or temperature change, and new cracks are generated. In addition, when the injection proceeds and the crack width is reduced, a portion where the cement particles cannot be injected occurs, and remains as a defect. In this case, rainwater or the like enters from the defects, deteriorating the concrete, and lowering the durability.

Therefore, after the water is sprinkled in Step 110 to sufficiently wet the construction surface, the silicate solution is sprayed or applied again on the concrete surface after the inorganic material is filled in Step 111. In this operation, after the cracks are roughly filled with the cement 14, the silicate solution is permeated into the remaining voids. Since the silicate solution is wetted in step 107, the silicate solution can be spread even between the fine particles of the cement 14 filled in step 109. The application of the silicate solution or the like is performed after the injected inorganic material is cured so as to have a certain level of strength. The standard of the curing time is about 12 hours.

Since the silicate solution is a solution having a small particle diameter of silicate and a low viscosity as described above, it penetrates into narrow gaps between cement particles and the like, and a groove or the like which rises vertically due to a capillary phenomenon. And is retained in the crack 11 without flowing out. By using such a silicate solution, it is possible to infiltrate the inside of a concrete surface by spraying or coating only, or even a small crack. After the application of the silicate solution, water is sprayed over the entire construction area in step 112 to sufficiently wet the construction surface.

The silicate solution reacts with calcium hydroxide contained in concrete via water (a porazone reaction) to generate alkali calcium silicate (gel). Specifically, the calcium ions combine with the silicate anion chains to form calcium silicate chains, which combine with each other to cause gelation. Due to this gelation, the above-mentioned space is closed, and intrusion of rainwater or the like is prevented. That is, as shown in FIG. 3C, the voids other than the portion filled with the cement 14 in the crack 11 are closed by the gel 15.

The silicate solution is preferably an alkali silicate aqueous solution prepared by mixing sodium silicate and potassium silicate among the above three materials. This is because sodium ions or potassium ions do not lengthen the silicate anion chain, but rather shorten it, thereby delaying gelation. As a result, the time required for gelation becomes longer, and the alkali silicate aqueous solution can be permeated deep into the concrete.

In this case, if the time required for gelation is too long, the effect of the gel for preventing intrusion of water or the like is not exhibited, so that the molar ratio of sodium silicate to potassium silicate is 3: 7 to 7: It is desirable to be within the range of 3.

塗布 The silicate solution can be applied in the same manner as the silicate solution or the fluidized inorganic material. The silicate solution used in step 107 and the silicate solution used in step 111 may be a solution in which the same two or more kinds of alkali silicates are mixed, or a mixture of two or more different kinds of alkali silicates. There may be. The amount of water to be added may be the same or different between the silicate solution used in step 107 and the silicate solution used in step 111.

In step 113, the groove is filled with an inorganic material (cement) as a filler to fill the groove. After filling the grooves, water is sprayed at step 114, and a silicate solution is sprayed or applied at step 115. Watering is performed within a few centimeters on both sides around the crack. The application of the silicate solution and the like are also performed in the same range as the watering. In this case, the silicate solution may be a solution obtained by mixing two or more kinds of alkali silicates same as the silicate solution used in step 107 or step 111, or may be a solution obtained by mixing two or more kinds of different alkali silicates. There may be. Further, the amount of water to be added may be the same as that of the silicate solution used in step 107 or step 111, or may be a different amount.

塗布 After applying the silicate solution, etc., in step 116, water is sprayed on the entire construction area to sufficiently wet the construction surface.

If the crack width is less than 0.3 mm as determined in step 104, the process proceeds to step 117, and water is sprayed without forming the above-mentioned grooves. In step 118, the silicate solution is injected into the concrete surface having cracks. Or spray or apply. Then, in step 119, water is sprinkled, and in step 120, the inorganic material fluidized by the addition of water is injected or applied and filled.

(4) After filling the inorganic material, water is sprinkled in step 121, and in step 122, the silicate solution is sprayed or applied to the concrete surface after filling the inorganic material. Thereafter, in step 123, water is sprayed on the entire construction section to sufficiently wet the construction surface.

確認 If the crack width is less than 0.2 mm in step 103, water is sprinkled in step 124, and then only spraying or coating of the silicate solution is performed in step 125. This is because the cracks themselves are small and it is not necessary to roughly fill the cracks with cement particles. In step 125, a silicate solution is injected to generate the gel 15 and close the void. After the application of the silicate solution or the like, water is sprayed on the entire construction area in step 126 to sufficiently wet the construction surface.

After watering in step 116 or step 123 or step 126, the process proceeds to step 127, where it is checked whether or not another crack exists. If there is, the process returns to step 102, and the same operation is performed for other cracks. Do.

(4) If it is confirmed in step 127 that the object does not exist, the process proceeds to step 128 to perform curing. During curing, water can be supplied by sprinkling water or the like in order to promote the reaction with calcium in the concrete. When it is sufficiently hardened, in step 129, repair of concrete cracks is completed.

Note that this work flow is merely an example, and instead of measuring and applying cracks one by one, all cracks may be measured at once and then coating etc. may be performed according to the crack width. Also, instead of waiting for all the coatings and the like to perform curing, curing may be performed each time one crack is applied and the like.

試験 Here are the tests and test results performed to test the effect of the repair by this method. In the test, as shown in FIG. 4, a plurality of projections 21 protruding from the inner surface of the case 20 toward the center are provided in a transparent acrylic case 20, and a plurality of holes 22 are formed on the plurality of projections 21. A plate 23 was placed on the plate 23, and two sets of two concrete blocks 24 were arranged on the plate 23 at regular intervals. FIG. 4 illustrates only one configuration.

One set the interval between the two concrete blocks 24 to 0.5 mm, and the other set the interval between the two concrete blocks 24 to 0.75 mm. Then, the upper periphery of each of the two concrete blocks 24 was sealed with a commercially available caulking material 25 as shown in FIG. FIG. 5 is a view of the case 20 as viewed from above. Thereby, a simulated crack was formed by the gap 26 between the two concrete blocks 24.

As shown in FIG. 6, an alkali silicate aqueous solution 27 containing sodium silicate and potassium silicate in a molar ratio of 5: 5 is placed on two concrete blocks 24 on the upper surface of two concrete blocks 24 whose periphery is sealed with a caulking material 25. 24, and the surface was wetted. In addition, the silicate solution was penetrated and reformed by a thickness of about several mm from the concrete surface inside the gap 26, and the reformed portion 28 was formed.

Next, cement (cement dispersion liquid) 29 fluidized by water was applied to the upper surfaces of the two concrete blocks 24. After a while, the cement 29 solidifies and loses its tackiness. After confirming that the tackiness had disappeared, the same aqueous alkali silicate solution as described above was again applied to the upper surfaces of the two concrete blocks 24 and cured for one week. The space between the two concrete blocks 24 after curing was filled with a filler (cement and formed gel) 30.

(7) The test was performed by placing water 32 on the upper part 31 of the acrylic case 20 and observing whether water leaked to the bottom part 33 of the acrylic case 20, as shown in FIG. The upper part 31 is the upper part of the two concrete blocks 24 sealed by the caulking material 25 and the filler 30 in the case 20, and the bottom part 33 is the lower part of the plate 23 in the case 20.

The bottom portion 33 was observed for several days with the intervals of 0.5 mm and 0.75 mm, but no water leakage was observed.

(4) From this, it was confirmed that even if the crack width was 0.2 mm or more, sufficient waterproofness and waterproofness could be imparted.

As described above, by using a combination of a silicate solution and an inorganic material fluidized by adding water, it is possible to appropriately cope with cracks in concrete, as described above. Therefore, this method effectively functions as a countermeasure against water leakage and water stoppage of concrete.

According to the present invention, in addition to the method for repairing cracks in concrete, a repair agent can also be provided. The repair agent is composed of a silicate solution and an aqueous filler mixed with an inorganic material. Aqueous fillers can also include admixtures to improve fluidization. Aqueous fillers can be filled by pouring or application into cracks having concrete surfaces moistened with a silicate solution.

Aqueous fillers can be produced by adding water and the like to an inorganic material at the site, mixing the resultant, and adding additives as necessary.

Although the concrete repair method of the present invention has been described in detail with the above-described embodiment, the present invention is not limited to the above-described embodiment, and may include other embodiments, additions, modifications, deletions, and the like. The present invention can be modified within a range that can be conceived by a person skilled in the art, and any embodiment is included in the scope of the present invention as long as the operation and effect of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 10 ... Concrete 11 ... Crack 12 ... Silicate solution 13 ... Modification part 14 ... Cement 15 ... Gel 20 ... Case 21 ... Projection 22 ... Plate 23 ... Hole 24 ... Concrete block 25 ... Caulking material 26 ... Crevice 27 ... Alkali silicate aqueous solution 28 reformer 29 cement 30 filler 31 top 32 water 33 bottom

Claims

A method of repairing concrete,
A first step of injecting, spraying or applying a solution containing silicate to the surface of the cracked concrete;
A second step of injecting or applying and filling an inorganic material fluidized by water into a crack having a surface of concrete wet with the solution containing the silicate,
A third step of spraying or applying a solution containing a silicate to the surface of the concrete after the inorganic material has been filled in the cracks.
The repair method according to claim 1, wherein the inorganic material is cement, and the silicate contains at least two of sodium silicate, potassium silicate, and lithium silicate.
3. The silicate according to claim 2, wherein the silicate contains two of sodium silicate, potassium silicate, and lithium silicate, and the two silicates are mixed in a molar ratio of 1: 9 to 9: 1. Repair method.
A fourth step of measuring a width of a crack formed in the concrete,
4. The method according to claim 1, wherein the first step, the second step, and the third step are performed when the measured width is equal to or more than a predetermined width. Repair method.
The repair method according to any one of claims 1 to 4, further comprising a fifth step of sprinkling water on the concrete after the third step.
6. The repair method according to claim 1, further comprising: a sixth step of forming a groove along the crack, and a seventh step of filling the groove with a filler.
A concrete repair agent,
A solution containing a silicate that is injected or sprayed or applied to the surface of the cracked concrete;
An aqueous filler mixed with an inorganic material, which is filled by injecting or coating the inside of a crack having a surface of concrete moistened by the solution containing the silicate,
The repair agent, wherein the solution containing the silicate is sprayed or applied to the surface of the concrete after the inside of the crack is filled with the aqueous filler.