JPWO2020004434A1 - Concrete reforming method and modifier - Google Patents

Abstract

Provided is a modification method capable of filling cracks with a gel even if the crack width is equal to or larger than a certain width, and can impart sufficient waterproofness and water stopping property. This method involves the first step of injecting, spraying or applying a solution containing silicate onto the surface of concrete with cracks, and flowing by water into the cracks having a surface of concrete moistened with the solution containing silicate. A second step of injecting or applying the silicate-based inorganic material to fill it, and a third step of spraying or applying a solution containing a silicate to the surface of the concrete after the inorganic material is filled in the cracks. And include. [Selection diagram] Fig. 1

Description

The present invention relates to a concrete reforming method and a modifying material, and more particularly to a modifying method and a modifying material for repairing cracks formed in concrete.

The surface layer 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, prevent deterioration of concrete, and aim for longer life. However, it is difficult to actually make concrete without cracks.

Therefore, in general, it is stipulated in the design and construction of construction and civil engineering structures that a certain degree of crack width is allowed for a concrete structure and appropriate measures are taken for a crack width exceeding this. The crack width of a general building structure is 0.3 mm, and that of a general civil engineering structure is 0.2 mm.

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

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

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

The present invention is a method for modifying concrete in view of the above problems.
The first step of injecting, spraying or applying a solution containing a silicate containing at least two kinds of sodium silicate, potassium silicate and lithium silicate to the surface of cracked concrete.
A second step of injecting or applying and filling an inorganic material fluidized by water inside a crack having a concrete surface moistened with a solution containing a silicate.
A reforming method is provided that includes 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 into the cracks.

According to the present invention, even if the crack width is equal to or larger than a certain width, the crack can be filled by the gel, and sufficient waterproofness and water stopping property can be imparted.

A flowchart showing the flow of work for repairing cracks formed in concrete. The figure explaining the state which the concrete has cracked. A conceptual diagram showing how each solution permeates a crack. An exemplary surface of a transparent container that houses two concrete blocks. The figure which illustrated the place where two concrete blocks were housed in a container, and the surroundings were sealed with a caulking material. The figure which illustrated the place which closed the gap between two concrete blocks. The figure which illustrated the place where water was filled on the upper part of two concrete blocks which closed a gap.

Concrete is made by putting cement, aggregate, water, and admixture into a mixer, kneading, assembling a formwork, placing it in the formwork, curing it so that condensation proceeds properly, and removing the mold. Manufactured in the desired shape.

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

Curing is the work of controlling the temperature and water content until the concrete is sufficiently hardened. In the curing work, 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 is sprinkled to keep the water content at a specified amount.

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

Cracks in concrete are acceptable as long as they have a certain width. On the other hand, it is required to take appropriate measures for the crack width exceeding this. Cracks that require treatment range from small cracks with a crack width of less than 0.2 mm to large cracks with a crack width of 0.2 mm or more. A method of repairing both of these will be described with reference to FIG.

FIG. 1 is a flowchart showing a work flow for repairing cracks formed in concrete. The work is started from step 100, and in step 101, the base of the concrete surface is cleaned so that the solution for repair can be easily injected. Cleaning of the base is performed by removing dust or the like using, for example, a brush, high-pressure water with fresh water, a wire brush, or the like.

The concrete 10 is formed with cracks 11 as shown in FIG. 2 due to the above factors. FIG. 2A is an example of a crack that can be seen in appearance, and FIG. 2B is an enlarged view of a cross section cut along the cutting line AA. When the crack 11 is formed, rainwater, carbon dioxide, or the like enters the concrete 10 through the crack 11, deteriorates the concrete 10, and rusts the internal reinforcing bars, thereby lowering the durability. Repairs are done to close this crack.

In step 102, the width of the crack on the concrete surface is measured. The crack width is the width of the crack shown in FIG. 2B, and a crack scale (ruler) or a system that calculates the width by imaging the crack with a camera and analyzing the captured image is used as a measuring instrument. Can be measured. The crack width is related to the size of the crack, and the larger the crack width, the easier it is for rainwater or the like to permeate, and the strength of the concrete decreases.

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

When the crack width is 0.3 mm or more, the process proceeds to step 105, and a grinding device such as a disc liner is used to form a groove having a U-shaped or V-shaped cross section along the crack. In this case, since the cracks are large and the cracks are likely to spread, a U-cut seal filling method for forming such a groove and increasing the adhesive area is also used in order to enhance the reinforcing effect.

After cleaning the inside of the groove with high-pressure water with fresh water or a wire brush or the like, the process proceeds to step 106, sprinkling water for deep penetration, and then in step 107, a solution containing silicate in the groove (hereinafter referred to as a silicate solution). ) Is injected or sprayed or applied to moisten the cracked surface. By making the cracks wet in this way, the concrete near the inner surface of the cracks is modified, and when the cracks are later filled with an inorganic material, the concrete is integrated with the concrete.

The silicate solution is an alkaline silicate aqueous solution prepared by mixing at least two, for example, sodium silicate, potassium silicate, and lithium silicate, and adding an appropriate amount of water. The alkaline silicate aqueous solution is a solution having a pH of 11 to 12, a silicate having a small particle size of about 1 to 10 nm, and a low viscosity of 6 to 8 (mPa · s). The reason for containing at least two kinds of alkali metals is to reduce the mobility of alkali metal ions by the mixed alkali effect in water, thereby suppressing the reaction with calcium ions, and to the deep part of concrete, for example, about 200 mm from the surface. This is because it is possible to deliver alkali metal ions up to. In addition, since alkali metal ions reach the deep part of the concrete, the silicate remaining in the form of sodium silicate and potassium silicate after the disappearance of water elutes the calcium ions in the deep part again when exposed to rainwater or the like after the fact. By forming silicates and gels, it is possible to provide an action of automatically repairing cracks and to provide repairability for a longer period of time.

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

If the gelation takes too long, the gel that prevents the infiltration of water and the like will not be exhibited. Therefore, the ratio of sodium silicate to potassium silicate is set to the above 3: 7 to 7: 3 in terms of molar ratio. It is desirable to keep it within the range of.

Further, in a specific embodiment, a silicate aqueous solution in which alkali metal ions are present in an equimolar ratio of 1: 1 in an aqueous solution of two types of silicates selected from sodium silicate, potassium silicate, and lithium silicate. It is preferable to use it together as a system concrete modifier. Aqueous silicate solution in which alkali metal ions are present in a molar ratio of 1: 1 penetrates deeply into concrete due to the mixed alkali effect, and reforms and protects concrete for a long period of time to the deep part, so that it has crack repairability. Has an excellent effect on concrete.

The silicate aqueous solution used in the present embodiment is not particularly limited, and is, for example, a silicate-based concrete modifier containing at least two kinds of silicates selected from sodium silicate, potassium silicate, and lithium silicate, for example, silicic acid. A silicate-based concrete modifier "Everprolong" manufactured by Nippon Prolong Co., Ltd., which contains sodium and potassium silicate in a molar ratio of alkali metal elements of 1: 1 can be used.

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

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

The crack 11 after the application of the silicate solution or the like is as shown in FIG. 3A, for example. With reference to FIG. 3A, the silicate solution permeates from the concrete surface inside the crack to form the modified portion 13, and the exposed surface inside the crack 11 is the silicate solution 12. It is in a wet state.

If the concrete slab to be repaired is a deck slab and cracks have penetrated, use an oil bottle or the like to inject a sufficient amount of the silicate solution with the intention of retaining it on the bottom surface.

After applying the silicate solution or the like, in step 108, the entire construction surface is sprinkled with water and placed in a wet state.

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

As the inorganic material, for example, cement can be used. Since the commonly used cement particles have a large particle size, they are preferably fine particles. By fluidizing the cement into a cement slurry, it becomes possible to inject it with a hand-held mortar pump. In addition, an admixture may be added as needed to improve fluidization.

Portland cement can be used as the cement, but the cement is not limited to this, and blast furnace cement, silica cement, fly ash cement and the like may be used. Blast furnace cement is a cement obtained by mixing fine powder of blast furnace slag and Portland cement, and silica cement is a cement obtained by mixing a natural siliceous mixture containing 60% or more of silica and Portland cement. Fly ash cement is a mixture of coal incinerator ash (fly ash) and Portland cement.

The injection of the cement slurry can be started with a low-concentration slurry and can be carried out 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. 3 (b). That is, a certain portion in the crack 11 is filled with the cement 14. This is because the cement fluidized by water has a larger particle size and a higher viscosity than the silicate solution, so that the cement does not immediately flow downward as in the silicate solution.

Since the crack filling by 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, it is possible to eliminate the occurrence of aging deterioration of the material. In addition, when used in combination with a silicate solution, it is possible to prevent the injected cement grout from exhibiting hardening and shrinkage phenomena, peeling off from concrete on the cracked surface, and generating new cracks.

Examples of the method of applying the fluidized inorganic material include brush coating, roll coating, spray coating and the like, as in the method of applying the silicate solution. A hand-held mortar pump can be used in the method of injecting fluidized inorganic material.

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 and temperature changes, and new cracks occur. Further, as the injection progresses and the crack width becomes smaller, 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 defect, deteriorates the concrete, and lowers the durability.

Therefore, after sprinkling water in step 110 to sufficiently moisten the construction surface, the silicate solution is sprayed or applied again on the concrete surface filled with the inorganic material in step 111. In this operation, the cracks are roughly filled with cement 14, and then the remaining voids are infiltrated with the silicate solution. Since it was moistened with the silicate solution in step 107, the silicate solution can be spread even among the fine particles of the cement 14 filled in step 109. The application of the silicate solution or the like is carried out after the injected inorganic material is cured so as to have some strength. The standard curing time is about 12 hours.

Since the silicate solution is a solution having a small particle size of silicate and a low viscosity as described above, it permeates into narrow gaps such as between cement particles, and a groove or the like rising in the vertical direction due to a capillary phenomenon. It also penetrates into the crack 11 and is retained in the crack 11 without flowing out. By using such a silicate solution, it is possible to permeate the inside even by spraying or applying it to the concrete surface or even small cracks. After spraying the silicate solution, water is sprinkled over the entire construction area in step 112 to sufficiently moisten the construction surface.

The silicate solution reacts with calcium hydroxide contained in concrete via water (porazone reaction) to produce alkali calcium silicate (gel). Specifically, calcium ions combine with chains of silicate anions to form calcium silicate chains, which combine with each other to cause gelation. This gelation closes the above voids and prevents the ingress of rainwater and the like. That is, as shown in FIG. 3C, the voids in the crack 11 other than the portion filled with the cement 14 are closed by the gel 15.

As the silicate solution, among the above three materials, an alkaline silicate aqueous solution prepared by mixing sodium silicate and potassium silicate is particularly preferable. This is because sodium and potassium ions act to shorten the chains of silicate anions rather than lengthen them, delaying gelation. As a result, the time required for gelation becomes longer, and the alkaline silicate aqueous solution can be permeated deep into the concrete.

In this case, if the time required for gelation becomes too long, the action of the gel that prevents the infiltration of water or the like is not exerted. It is desirable to keep it within the range of 3.

As for the application of the silicate solution or the like, the same method as the application of the silicate solution or the fluidized inorganic material can be used. The silicate solution used in step 107 and the silicate solution used in step 111 may be a mixture of the same two or more kinds of alkali silicates, or a mixture of two or more different kinds of alkali silicates. There may be. Further, the amount of water 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 filling material to fill the groove. After filling this groove, watering is performed in step 114, and the silicate solution is sprayed or applied in step 115. Watering should be done within a few centimeters on both sides, centered on cracks. Apply the silicate solution in the same range as watering. The silicate solution in this case may be a solution in which the same two or more kinds of alkali silicates as the silicate solution used in step 107 or step 111 are mixed, or a solution in which two or more different kinds of alkali silicates are mixed. There may be. Further, the amount of water added may be the same as or different from the amount of the silicate solution used in step 107 or step 111.

After applying the silicate solution or the like, water is sprinkled over the entire construction area in step 116 to sufficiently moisten the construction surface.

If the crack width is less than 0.3 mm in the confirmation in step 104, the process proceeds to step 117, water is sprinkled without forming the above groove, and then in step 118, the silicate solution is injected into the cracked concrete surface. Alternatively, spray or apply. Then, water is sprinkled in step 119, and an inorganic material fluidized by water is injected or applied and filled in step 120.

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. Then, in step 123, water is sprinkled over the entire construction area to sufficiently moisten the construction surface.

In the confirmation of step 103, if the crack width is less than 0.2 mm, 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, so it is not necessary to coarsely fill the cracks with cement particles. In step 125, a silicate solution is injected to generate gel 15 and close the voids. After applying the silicate solution or the like, water is sprinkled over the entire construction area in step 126 to sufficiently moisten the construction surface.

After sprinkling water in step 116, step 123, or step 126, the process proceeds to step 127 to check if there are other cracks, and if so, the process returns to step 102, and the same operation is performed for the other cracks. conduct.

If it is confirmed in Tep 127 that it does not exist, the process proceeds to step 128 and curing is performed. At the time of 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, the repair of cracks in the concrete is completed in step 129.

Note that this work flow is an example, and instead of measuring and applying cracks one by one, all cracks may be measured at once, and then coating or the like may be performed according to the crack width. Further, instead of waiting for all the coatings and the like to be cured, the curing may be performed every time one crack is coated or the like.

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

One is that the distance between the two concrete blocks 24 is 0.5 mm, and the other is that the distance between the two concrete blocks 24 is 0.75 mm. Then, as shown in FIG. 5, the upper periphery of each of the two concrete blocks 24 was sealed with a commercially available caulking material 25. FIG. 5 is a top view of the case 20. As a result, a simulated crack was formed by the gap 26 between the two concrete blocks 24.

As shown in FIG. 6, an alkaline silicate aqueous solution 27 (Nippon Prolong Co., Ltd.) containing sodium silicate and potassium silicate in a molar ratio of 5: 5 on the upper surface of two concrete blocks 24 whose periphery is sealed with a caulking material 25. , Everprolong) was applied to the upper surfaces of the two concrete blocks 24 to moisten the surfaces. Further, the silicate solution permeated from the concrete surface inside the gap 26 to a thickness of about several mm and modified to form the modified portion 28.

Next, cement (cement dispersion) 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 adhesiveness. After confirming that the adhesiveness had disappeared, the same alkaline silicate aqueous solution as described above was applied again 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 closed by a filling (cement and gel produced) 30.

As shown in FIG. 7, the test was carried out by filling the upper portion 31 of the acrylic case 20 with water 32 and observing whether or not water leaked to the bottom 33 of the acrylic case 20. The upper portion 31 is the upper portion of the two concrete blocks 24 sealed by the caulking material 25 and the filling 30 in the case 20, and the bottom portion 33 is the lower portion of the plate 23 in the case 20.

Although the intervals were set to 0.5 mm and 0.75 mm, the bottom 33 was observed for several days, but no water leakage was observed in any of them.

From this, it was confirmed that even if the crack width is 0.2 mm or more, sufficient waterproofness and water stopping property can be imparted.

As described above, for complex cracks in concrete, cracks in concrete can be appropriately dealt with by using a silicate solution and an inorganic material fluidized by water in combination. Therefore, this method effectively exerts its function as a measure against water leakage and water stoppage of concrete.

In the present invention, in addition to a method for modifying cracks in concrete, a modifier can also be provided. The modifier is composed of a silicate solution and an aqueous filler in which an inorganic material is mixed. The aqueous filler may also contain an admixture to improve fluidization. The aqueous filler can be filled by injection or coating inside a crack having a concrete surface moistened with a silicate solution.

The aqueous filler can be produced by adding water or the like to an inorganic material at the site, mixing the mixture, and adding an additive if necessary.

Although the concrete reforming method of the present invention has been described in detail with the above-described embodiments, the present invention is not limited to the above-described embodiments, and other embodiments, additions, changes, and deletions are made. Such as, can be changed within a range that can be conceived by a person skilled in the art, and is included in the scope of the present invention as long as the action / effect of the present invention is exhibited in any of the embodiments.

10 ... Concrete 11 ... Crack 12 ... Silicate solution 13 ... Modified part 14 ... Cement 15 ... Gel 20 ... Case 21 ... Projection 22 ... Plate 23 ... Hole 24 ... Concrete block 25 ... Coking material 26 ... Gap 27 ... Alkaline silicate aqueous solution 28 ... Modification 29 ... Cement 30 ... Filling 31 ... Top 32 ... Water 33 ... Bottom

Claims (9)

It ’s a concrete reforming method.
The first step of injecting, spraying or applying a solution containing a silicate containing at least two kinds of sodium silicate, potassium silicate and lithium silicate to the surface of cracked concrete.
A second step of injecting or applying an inorganic material fluidized by water to fill the inside of the crack having a concrete surface moistened with the solution containing the silicate.
A modification method comprising a third step of spraying or applying a solution containing a silicate to the surface of concrete after the inorganic material is filled in the cracks. The modification 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. The second aspect of claim 2, wherein the silicate contains two of sodium silicate, potassium silicate, and lithium silicate, and the two silicates are blended in a molar ratio of 1: 9 to 9: 1. Modification method. The modification method according to claim 1, wherein the silicate contains two of sodium silicate, potassium silicate, and lithium silicate, and the two silicates are blended in a molar ratio of 1: 1. Including a fourth step of measuring the width of the cracks formed in the concrete.
The method according to any one of claims 1 to 4, wherein the first step, the second step, and the third step are carried out when the measured width is equal to or larger than a predetermined width. Modification method. The reforming method according to any one of claims 1 to 5, further comprising a fifth step of sprinkling water on the concrete after the third step. The modification method according to any one of claims 1 to 6, further comprising a sixth step of forming a groove along the crack and a seventh step of filling the groove with a filler. It is a concrete modifier
A solution containing at least two silicates injected or sprayed or applied to the surface of cracked concrete and selected from sodium silicate, potassium silicate and lithium silicate.
It is composed of an aqueous filler mixed with an inorganic material that fills the inside of a crack having a concrete surface moistened with a solution containing the silicate by injection or coating.
The solution containing the silicate is a modifier that is sprayed or applied to the surface of concrete after the inside of the crack is filled with the aqueous filler. The modifier according to claim 8, wherein the solution contains at least an equimolar amount of an element of sodium and an element of potassium.

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