Concrete foundation structure and coating method of concrete foundation structure

Abstract

To provide a concrete foundation structure with neutralization prevention function.SOLUTION: A concrete foundation structure comprises: a modified layer formed from a neutralization inhibitor containing sodium silicate with a molar ratio of SiO2 / Na2O of 1.6 to 2.06 and concentration of silicon dioxide of 8 to 14 mass% at an inner surface side of an erected part except outer surface sides; and protective layers formed from cement mortar containing cement, synthetic resin and aggregates with at least 30 mass% of aggregate particles not passing through 300 μm nominal mesh openings of metallic sieve and at least 20 mass% thereof passing through 180 μm nominal mesh openings at the outer surface sides of the erected part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technical field of the present specification relates to an anti-carbonation agent and cement mortar that prevent carbonation of concrete, and a concrete structure provided with a modified layer formed from the anti-carbonation agent and a protective layer formed from the cement mortar. [Background technology]

[0002] Conventionally, a silicate-based surface modifier for concrete, as disclosed in Patent Document 1 below, has been known, in which the silicate concentration is 15 to 24 mass % and the SiO2 / Na2O molar ratio is 2.3 to 2.7. It is known that concrete modified with this surface modifier has a low water permeability and excellent density. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6309140 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional surface modifiers have not been studied in terms of application workability.

[0005] The problem to be solved by the technology of this specification has been achieved in view of the above points, and an object of the present invention is to provide a neutralization inhibitor that has a neutralization prevention function and can be spray-coated. [Means for solving the problem]

[0006] The carbonation inhibitor according to an embodiment of the present specification is an inhibitor for preventing carbonation of concrete, Contains sodium silicate, The sodium silicate is characterized in that the SiO2 / Na2O molar ratio specified in JIS K 1408:1966 is 2.5 or less.

[0007] According to the anti-neutralization agent according to the embodiment of this specification, the alkalinity of sodium silicate provides an anti-neutralization function, and sodium silicate with a molar ratio of 2.5 or less is chemically stable, making it possible to apply the agent to concrete by spray coating.

[0008] Here, in the above-mentioned neutralization inhibitor, the molar ratio of the sodium silicate may be 1.6 or more, and the concentration of silicon dioxide may be 8 to 15 mass %.

[0009] This allows the components formed by the reaction between the silicon dioxide in sodium silicate and the calcium in the concrete to block the pores on the surface of the concrete, thereby enhancing the effectiveness of preventing carbonation of concrete that has a modified layer formed by the application of a carbonation inhibitor.

[0010] The neutralization inhibitor may contain a synthetic resin emulsion.

[0011] According to this, since the synthetic resin is dispersed in the modified layer, the water resistance of the concrete that is applied can be improved.

[0012] Here, the cement mortar according to the embodiment of the present specification is a cement mortar used in combination with the above-mentioned anti-carbonation agent, Contains cement, synthetic resin and aggregate, The aggregate has at least 30% by mass of aggregate particles that do not pass through a metal mesh sieve (JIS Z 8801-1:2019) with a nominal opening of 300 μm, and at least 20% by mass that pass through a nominal opening of 180 μm. It is characterized by:

[0013] According to the cement mortar of the embodiment of the present specification, the protective layer formed from the cement mortar can prevent the concrete from being neutralized because the cement imparts alkalinity to the concrete, and the combination of aggregate particle sizes and the dispersion of synthetic resin can increase the water resistance of the protective layer.

[0014] Here, the concrete structure according to an embodiment of the present specification is characterized in that it has a modified layer formed from the above-mentioned anti-neutralization agent on the inner surface side, and a protective layer formed from the above-mentioned cement mortar on the outer surface side.

[0015] According to the concrete structure of the embodiment of this specification, the outer surface exposed to rainwater, etc. is provided with a protective layer formed from cement mortar, thereby enabling appropriate prevention of neutralization. [Effects of the Invention]

[0016] The neutralization inhibitor described in this specification has a neutralization prevention function and can be applied by spray coating. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a vertical cross-sectional view of a concrete structure to which an anti-carbonation agent and cement mortar according to an embodiment have been applied. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a carbonation inhibitor, cement mortar, and concrete structure according to embodiments of the present specification will be described. Note that the scope of the present invention is not limited to the scope disclosed in the embodiments. As shown in FIG. 1 , the carbonation inhibitor according to the embodiment is applied to concrete 11 to form a modified layer 13 that prevents carbonation of the concrete 11. The cement mortar according to the embodiment is applied to concrete 11 to form a protective layer 15 that prevents carbonation of the concrete 11. Furthermore, the concrete structure 1 according to the embodiment has a modified layer 13 formed from the carbonation inhibitor on the inner surface side and a protective layer 15 formed from cement mortar on the outer surface side, thereby enabling appropriate carbonation prevention.

[0019] The anti-neutralization agent in the embodiment that forms the modified layer 13 contains sodium silicate (water glass), sodium hydroxide, and diluted water, and has a molar ratio (SiO2 / Na2O) of 2.5 or less as specified in JIS K 1408:1966 (sodium silicate (sodium silicate)).

[0020] When the anti-carbonation agent is applied to concrete 11, the sodium ions (sodium oxide (Na2O)) of the anti-carbonation agent penetrate into concrete 11, thereby exerting its anti-carbonation function. In addition, silicate ion micelles eluted from the silicon dioxide of sodium silicate combine with calcium in concrete 11, forming calcium silicate that blocks pores on the surface of concrete 11, thereby inhibiting the penetration of carbonation-promoting components such as carbon dioxide and acid rain into concrete 11.

[0021] The inventors of the present application have discovered that when the molar ratio (SiO2 / Na2O) of the anti-carbonation agent is 2.5 or less, the anti-carbonation agent can be applied by spray coating. When the molar ratio of the anti-carbonation agent is 2.5 or less, silicon dioxide (SiO2), which lacks chemical stability, is dissolved by sodium ions, thereby chemically stabilizing it, making application by spray coating possible. If the molar ratio of the anti-carbonation agent exceeds 2.5, silicon dioxide lacks chemical stability, and there is a risk that silicon dioxide will precipitate at the spray gun outlet during spray coating, causing clogging. In another embodiment, the molar ratio of the anti-carbonation agent can be 1.6 to 2.4. If the molar ratio of the anti-carbonation agent is less than 1.6, application by spray coating is possible, but since the sodium ions (sodium oxide) are contained in excess, the sodium ions may redissolve the calcium silicate that has filled the pores on the surface of the concrete 11, and the anti-carbonation effect may not be sufficiently obtained. In yet another embodiment, the molar ratio of the anti-carbonation agent may be 1.85 to 2.25.

[0022] In the embodiment, the anti-carbonation agent may contain 4 to 9 mass% sodium oxide. This is because the anti-carbonation effect of concrete 11 having a modified layer 13 formed from the anti-carbonation agent after application can be exerted. If the sodium oxide content is less than 4 mass%, the alkalinity (sodium ions) is low and the anti-carbonation effect may not be sufficiently exerted. On the other hand, if it exceeds 9 mass%, the water resistance of the modified layer 13 may be poor due to the high affinity of sodium oxide for water. In another embodiment, the sodium oxide content of the anti-carbonation agent may be 4.5 to 8 mass%, and in yet another embodiment, 5 to 7 mass%.

[0023] In an embodiment, the anti-carbonation agent may contain 8 to 14 mass% silicon dioxide. This is because the anti-carbonation agent can exhibit the effect of preventing carbonation of concrete 11 that has been applied and has a modified layer 13 formed from the anti-carbonation agent. If the silicon dioxide content is less than 8 mass%, the total amount of silicon dioxide contained in the anti-carbonation agent is small, and there is a risk that the pores on the surface of concrete 11 may not be sufficiently blocked. On the other hand, if the silicon dioxide content exceeds 14 mass%, depending on the molar ratio, the sodium oxide content may become relatively high, and there is a risk that the water resistance of the modified layer 13 formed from the anti-carbonation agent may be poor. In another embodiment, the silicon dioxide content of the anti-carbonation agent may be 9 to 13 mass%, and in yet another embodiment, 9.5 to 12 mass%.

[0024] The anti-neutralization agent of the embodiment can be prepared by appropriately adding sodium hydroxide and dilution water to sodium silicate (water glass).

[0025] In addition, the neutralization inhibitor of the embodiment may contain a synthetic resin emulsion. By including a synthetic resin emulsion, the modified layer 13 formed from the neutralization inhibitor can have improved water resistance. Synthetic resins that can be used to form the synthetic resin emulsion include acrylic resin, vinyl acetate resin, vinyl versatate resin, ethylene-vinyl acetate copolymer resin, and styrene-butadiene resin. In another embodiment, the neutralization inhibitor may contain a styrene-butadiene resin emulsion, which can further improve water resistance.

[0026] The cement mortar of the embodiment can be a one-component cement mortar made by mixing a mortar powder main material with mixing water, or a two-component cement mortar made by mixing a mortar powder main material with a cement mortar admixture (including mixing water). When the cement mortar is applied to concrete 11, a protective layer 15 that prevents the concrete 11 from being neutralized is formed.

[0027] The main powder material of cement mortar contains, in detail, cement, re-emulsifiable powder resin (synthetic resin), aggregate, and may optionally contain thickener, fiber, and termite inhibitor. These are all powdered raw materials, and can be made into the main powder material of cement mortar by mixing them using a powder mixer such as a Nauta mixer or paddle mixer.

[0028] Cement is a material that hardens when combined with water, and ordinary Portland cement as defined in JIS R 5210-2019 can be suitably used. Other cements can also be used in the cement mortar as long as they do not impair the effects of the present invention. Examples of other cements that can be used include high-early-strength cement, ultra-high-early-strength cement, and white cement.

[0029] Re-emulsifiable powder resin is a fine powder resin obtained by drying a synthetic resin emulsion produced by emulsion polymerization in a particulate state. It re-emulsifies when water is added and stirred. When blended with cement mortar, re-emulsifiable powder resin enhances the water resistance of the protective layer 15 formed from the cement mortar and provides flexibility to the protective layer 15, allowing it to adapt to the expansion and contraction of the concrete 11. This makes it suitable for application to the exterior surfaces of concrete structures exposed to rainwater, etc. (Figure 1). Re-emulsifiable powder resins can be those specified in the "Polymer Dispersions for Cement Admixtures and Re-emulsifiable Powder Resins" (JIS A 6203:2015). Commercially available re-emulsifiable powder resins include Movinyl Powder (Japan Coating Resins Co., Ltd.), Sumikaflex (Sumika Chemtex Corporation), Acronal (BASF Ltd.), and ELOTEX (Celanese Japan Co., Ltd.). In the cement mortar of the embodiment, the blending amount of the re-emulsifiable powdered resin is 20 to 100 parts by mass per 100 parts by mass of cement in the case of a one-component cement mortar. If the blending amount of the re-emulsifiable powdered resin is less than 20 parts by mass per 100 parts by mass of cement, the water resistance of the protective layer 15 may not be improved. On the other hand, if the blending amount exceeds 100 parts by mass per 100 parts by mass of cement, the re-emulsifiable powdered resin contains a large amount of components that are compatible with water, and the water resistance of the protective layer 15 may be poor. In another embodiment, the blending amount of the re-emulsifiable powdered resin may be 30 to 80 parts by mass per 100 parts by mass of cement, and in yet another embodiment, 40 to 60 parts by mass. In the case of a two-component cement mortar, the blending amount of the re-emulsifiable powdered resin may be 5 to 100 parts by mass per 100 parts by mass of cement, and in another embodiment, 10 to 80 parts by mass, and in yet another embodiment, 20 to 60 parts by mass.

[0030] Aggregate is a material that, when mixed with cement mortar, improves the physical strength of the protective layer 15 formed from the cement mortar while reducing raw material costs as a cement mortar extender. Examples of aggregates suitable for the cement mortar of this embodiment include silica sand, kansui stone (ground limestone), and crushed stone powder. In another embodiment, silica sand can be used. In the cement mortar of this embodiment, the amount of aggregate mixed is 50 to 800 parts by mass per 100 parts by mass of cement. If the amount of aggregate mixed is less than 50 parts by mass per 100 parts by mass of cement, the physical strength of the protective layer 15 may not be increased. On the other hand, if the amount of aggregate mixed is more than 800 parts by mass per 100 parts by mass of cement, the strength of the protective layer 15 may be reduced due to the small amount of binder (cement, synthetic resin) relative to the aggregate. In another embodiment, the amount of aggregate mixed can be 100 to 600 parts by mass per 100 parts by mass of cement, and in yet another embodiment, 200 to 400 parts by mass.

[0031] In one embodiment, the aggregate may have a particle size that contains at least 30% by mass of coarse particles that do not pass through a metal mesh sieve (JIS Z 8801-1:2019) with a nominal mesh size of 300 μm, and at least 20% by mass of fine particles that pass through a nominal mesh size of 180 μm. This is because the combination of coarse and fine particles makes the protective layer 15 formed from cement mortar dense, thereby increasing the water resistance of the protective layer 15. In another embodiment, the aggregate may have a particle size that contains at least 40% by mass of coarse particles that do not pass through a metal mesh sieve with a nominal mesh size of 300 μm, and at least 30% by mass of fine particles that pass through a nominal mesh size of 180 μm.

[0032] Thickeners are materials added to adjust the workability of cement mortar during construction and to prevent sagging. Thickeners that can be added include methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), and hydroxyethyl methyl cellulose (HEMC).

[0033] Fibers are materials added to adjust the workability of cement mortar during application and to prevent sagging. Fibers can be selected appropriately from synthetic resin fibers, glass fibers, and the like.

[0034] Anti-termite agents are additives that repel ants. Examples of anti-termite agents include pyrethroid compounds such as acrinathrin, etofenprox, and bifenthrin; insect growth regulators such as chlorfluazuron, flufenoxuron, and methoxyfenozide; insecticides such as chlorfenapyr, fipronil, and ethiprole; and (E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine or 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine. These anti-termite agents are preferably coated with a synthetic resin and in powder form. Coating the anti-termite agent with a synthetic resin particularly helps prevent inactivation by alkaline cement mortar and concrete neutralization inhibitors.

[0035] Specifically, the cement mortar admixture contains a synthetic resin emulsion, and may optionally contain water, an antifoaming agent, a thickener, a preservative, and a pH adjuster. These ingredients can be mixed using a mixer such as a dissolver mixer to form the cement mortar admixture.

[0036] The synthetic resin emulsion may be a commercially available product compatible with cement, such as Polytron (manufactured by Asahi Kasei Corporation), Pegal (manufactured by Koatsu Gas Kogyo Co., Ltd.), or Acronal (manufactured by BASF Ltd.).

[0037] Water also functions as mixing water for cement, and therefore can be omitted if the water contained in the synthetic resin emulsion can provide the required mixing water for cement.

[0038] The antifoaming agent suppresses foaming of the cement mortar admixture, and commercially available products can be used as appropriate. The thickener suppresses settling and separation of the cement mortar admixture, and commercially available products can be used as appropriate. The preservative suppresses putrefaction of the cement mortar admixture, and commercially available products can be used as appropriate. The pH adjuster adjusts the pH of the cement mortar admixture and suppresses settling and separation, and commercially available products can be used as appropriate.

[0039] The carbonation inhibitor and cement mortar of the embodiment can be applied to a concrete structure 1 such as a concrete foundation (mat foundation, strip foundation), a reinforced concrete building, a reinforced concrete structure, or a bridge substructure (abutment, pier).

[0040] Next, a method for applying the anti-carbonation agent and cement mortar according to the embodiment will be described using an example of application to a mat foundation as shown in FIG.

[0041] The anti-carbonation agent is applied using a spray paint machine such as a battery-powered sprayer or a manual sprayer to the concrete foundation (mat foundation) after pouring and demolding the concrete foundation (concrete 11). These spray paint machines do not require a power source or special equipment, so they can be applied to any area, even on concrete structures 1 where a power source is not available. The spray pressure of these spray paint machines is 0.3 to 1.5 MPa.

[0042] During application, the anti-carbonation agent has a molar ratio of 2.5 or less, so clogging does not occur at the spray nozzle. Because spray application is possible, the anti-carbonation agent can be applied more quickly than with other application methods (such as roller application or brush application). By applying the anti-carbonation agent, a modified layer 13 with anti-carbonation properties is formed on the solid foundation (concrete 11).

[0043] As shown in Figure 1, the anti-carbonation agent is applied (painted) on the inner surface of the slab foundation, excluding the outer surface. This is because the inner surface is less exposed to rainwater, etc., once the building is constructed. In addition, to prevent unpainted areas from occurring, the agent can be applied up to the top edge of the outer surface of the slab foundation.

[0044] After the application of the anti-carbonation agent, cement mortar is applied, but this can be done after the building, excluding the interior, has been constructed. The cement mortar is applied on the outer surface of the slab foundation, within a range that can be visually confirmed, in order to prevent damage to the protective layer 15 formed from the cement mortar during the construction of the building. The cement mortar is applied using a roller or plastering trowel that can ensure a sufficient coating thickness. In this embodiment, a porous roller is used as the roller for applying the cement mortar. By applying the cement mortar, a protective layer 15 that has anti-carbonation properties and water resistance is formed on the outer surface of the slab foundation (concrete 11). A general-purpose colored paint can be applied to the upper side (surface side) of the protective layer 15 to form a colored layer 16.

[0045] The concrete structure 1 thus formed exhibits anti-carbonation function on the inner surface due to the alkalinity of the modified layer 13 made of sodium silicate. On the outer surface, the cement contained in the protective layer 15 made of cement mortar exhibits anti-carbonation function, and the combination of aggregate particle sizes and the dispersed synthetic resin provide water resistance. [Example]

[0046] The anti-neutralization agents of the embodiment having different compositions were subjected to the sprayability test and the anti-neutralization test described below, and were evaluated.

[0047] Sprayability test The sprayability test was conducted by pouring 4 L of the anti-neutralization agent into a sprayer with a 5 L tank capacity (battery-powered sprayer IR-N5000 (manufactured by Iris Ohyama Co., Ltd.)) and continuously spraying 4 L of the anti-neutralization agent. The test results were evaluated as follows: ○ if all 4 L of the anti-neutralization agent was able to be sprayed and no clogging occurred in the nozzle; △ if all 4 L was able to be sprayed but the nozzle was clogged and a change in the discharge amount was observed; and × if the nozzle was clogged and it was not possible to spray all 4 L.

[0048] Anti-neutralization test The specimen for the carbonation prevention test was a 40 x 40 x 160 mm cement mortar (cement:sand = 1:3) with 100 g / m2 of carbonation prevention agent applied to all six sides. 2 The test specimens were prepared using a coating amount of 100g. The carbonation prevention test involved exposing the specimens outdoors for six months, splitting them laterally at approximately the center of the longitudinal direction, spraying a phenolphthalein solution (1%) on the cross section, and measuring the carbonation depth at which the specimens did not turn purple. The test results were evaluated as follows: a carbonation depth of 1mm or less was marked ○, a carbonation depth of more than 1mm but not more than 3mm was marked △, and a carbonation depth of more than 3mm was marked ×.

[0049] Test examples of the neutralization inhibitor are shown in Table 1. Test Examples 1 to 6, 9, and 10 are working examples, and Test Examples 7 and 8 are comparative examples.

[0050] [Table 1]

[0051] (Test Examples 1 to 6) Test Examples 1 to 6 are test examples in which the SiO2 / Na2O molar ratio of sodium silicate is 1.6 to 2.5. In Test Examples 1 to 6, the SiO2 / Na2O molar ratio is 2.5 or less, so in the sprayability test, all 4 L could be sprayed without nozzle clogging, and because the molar ratio is 1.6 or more, the carbonation prevention performance was also fully satisfied. Note that Test Example 5, with a molar ratio of 1.86, achieved a result of ○ in the carbonation prevention test, but the value was close to the limit. Furthermore, among these test examples, Test Examples 1 to 4 were the best, and it was difficult to judge their performance, but if one had to be chosen, it would be Test Example 1.

[0052] (Test Examples 7 and 8) Test Examples 7 and 8 are test examples in which the SiO2 / Na2O molar ratio of sodium silicate exceeds 2.5. In Test Examples 7 and 8, because the SiO2 / Na2O molar ratio exceeds 2.5, clogging occurred in the nozzle during the sprayability test, and it was not possible to spray all 4 L. However, the carbonation prevention performance was fully satisfied.

[0053] (Test Examples 9 and 10) Test Examples 9 and 10 are test examples in which the SiO2 / Na2O molar ratios of the sodium silicate were 1.65 and 1.60, respectively. In the sprayability test, Test Examples 9 and 10 were able to spray all 4 L without clogging the nozzle, but their anti-carbonation performance was slightly inferior.

[0054] The cement mortars of the embodiment having different compositions were subjected to the water resistance test described below and the carbonation prevention test described above, and were evaluated.

[0055] Water resistance test The water resistance test was conducted in accordance with JIS A 6909:2014 (Architectural Finish Coating Materials) Water Permeability Test Method B. The test results were evaluated as follows: ○ for a water permeability of 0.5 mL or less, △ for a water permeability of more than 0.5 mL but not more than 1.0 mL, and × for a water permeability of more than 1.0 mL.

[0056] Test examples of cement mortar are shown in Table 2. Test Examples 11 to 13 are working examples, and Test Examples 14 and 15 are comparative examples. The particle size distribution of the silica sand contained in the cement mortar is shown in Table 3, and the formulation of the cement mortar admixture is shown in Table 4.

[0057] [Table 2]

[0058] [Table 3]

[0059] [Table 4]

[0060] (Test Example 11) Test Example 11 is a one-component cement mortar containing 300 parts by mass of aggregate per 100 parts by mass of cement, thereby increasing the physical strength of protective layer 15. Furthermore, in Test Example 11, the aggregate contains at least 30% by mass of coarse particles that do not pass through a metal mesh sieve with a nominal opening of 300 μm and at least 20% by mass of fine particles that pass through a nominal opening of 180 μm, so the combination of coarse and fine particles increases the water resistance of protective layer 15, and the re-emulsifiable powder resin further increases the water resistance of protective layer 15.

[0061] (Test Examples 12 and 13) Test Examples 12 and 13 are two-component cement mortars containing 300 parts by mass of aggregate per 100 parts by mass of cement, thereby enhancing the physical strength of protective layer 15. Furthermore, in Test Examples 12 and 13, the aggregate contains at least 30% by mass of coarse particles that do not pass through a metal mesh sieve with a nominal mesh opening of 300 μm and at least 20% by mass of fine particles that pass through a nominal mesh opening of 180 μm, thereby enhancing the water resistance of protective layer 15 through the combination of coarse and fine particles. Furthermore, in Test Examples 12 and 13, the water resistance of protective layer 15 is further enhanced by the acrylic resin contained in the cement mortar admixture. Test Examples 12 and 13 differ in the particle size distribution of the aggregate.

[0062] (Test Examples 14 and 15) Test Examples 14 and 15 were obtained by further changing the aggregate particle size distribution from Test Examples 12 and 13. Test Example 14 had an aggregate particle size in which coarse particles that did not pass through a metal mesh sieve with a nominal mesh opening of 300 μm accounted for less than 30% by mass. Test Example 15 had an aggregate particle size in which fine particles that passed through a nominal mesh opening of 180 μm accounted for less than 20% by mass. As a result, Test Examples 14 and 15 had poorer water resistance and, as a result, slightly poorer anti-carbonation properties. [Explanation of symbols]

[0063] 1...concrete structure, 11...concrete, 13...modified layer, 15...protective layer, 16...colored layer

Claims

1. SiO defined in sodium silicate (JIS K 1408:1966) 2 / Na 2 a modified layer formed from an anti-neutralization agent containing sodium silicate having a molar ratio of O of 1.6 to 2.06 and a silicon dioxide concentration of 8 to 14 mass % is provided on the inner surface side of the raised portion excluding the outer surface side; The raised portion is provided on the outer surface side with a protective layer formed from cement mortar containing cement, synthetic resin, and aggregate, wherein at least 30% by mass of the aggregate particles do not pass through a metal mesh sieve (JIS Z 8801-1:2019) with a nominal mesh opening of 300 μm, and at least 20% by mass of the aggregate particles pass through a nominal mesh opening of 180 μm. A concrete foundation structure characterized by:

2. SiO defined in sodium silicate (JIS K 1408:1966) 2 / Na 2 an anti-neutralization agent containing sodium silicate having a molar ratio of O of 1.6 to 2.06 and a silicon dioxide concentration of 8 to 14 mass % is applied to the inner surface side of the raised portion excluding the outer surface side using a battery-powered sprayer or a manual sprayer; A cement mortar containing cement, synthetic resin, and aggregate, wherein at least 30% by mass of the aggregate particles do not pass through a metal mesh sieve (JIS Z 8801-1:2019) with a nominal mesh opening of 300 μm and at least 20% by mass passes through a nominal mesh opening of 180 μm, is applied to the outer surface side of the raised portion using a roller or a plastering trowel.

1. A method for coating a concrete foundation structure.

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