Concrete foundation structures and painting methods for concrete foundation structures

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 a carbonation inhibitor for preventing carbonation of concrete, cement mortar, and a concrete structure provided with a modified layer formed from the carbonation inhibitor and a protective layer formed from the cement mortar.

BACKGROUND ART

[0002] As a concrete surface modifier, conventionally, in the following Patent Document 1, a silicate-based surface modifier having a silicic acid concentration of 15 to 24 mass% and a SiO₂ / Na₂O molar ratio of 2.3 to 2.7 is known, and it is known that concrete modified with this surface modifier has a suppressed water permeability ratio and can achieve excellent denseness.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

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

[0005] The problem to be solved by the technology of the present specification has been made in view of the above points, and an object thereof is to provide a carbonation inhibitor that has a carbonation inhibiting function and is spray-coatable.

MEANS FOR SOLVING THE PROBLEMS

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

[0007] According to the embodiment of this specification, the neutralization inhibitor has a neutralization inhibitory function due to the alkalinity of sodium silicate, and since the sodium silicate with a molar ratio of 2.5 or less is chemically stable, it can be applied to concrete by spray coating.

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

[0009] According to this, the components formed by the reaction between the silicon dioxide in sodium silicate and the calcium in concrete can clog the pores on the surface of the concrete, thereby enhancing the carbonation prevention effect of concrete that has a modified layer formed by the application of a carbonation inhibitor.

[0010] Furthermore, the above-mentioned neutralization inhibitor may contain a synthetic resin emulsion.

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

[0012] Here, the cement mortar according to the embodiment of this specification is a cement mortar used in combination with the above-mentioned carbonation inhibitor, It contains cement, synthetic resin and aggregate, The aggregate is such that 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 pass through a metal mesh sieve with a nominal mesh opening of 180 μm. It is characterized by the following:

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

[0014] Herein, the concrete structure according to the embodiment of this specification is characterized by having a modified layer formed from the above-mentioned carbonation inhibitor on the inner surface and a protective layer formed from the above-mentioned cement mortar on the outer surface.

[0015] According to the concrete structure of the embodiment described herein, a protective layer made of cement mortar is provided on the outer surface that is exposed to rainwater, etc., so that neutralization can be properly prevented. [Effects of the Invention]

[0016] According to the carbonation inhibitor specified herein, it is possible to have a carbonation inhibitory function and to apply it by spray painting. [Brief explanation of the drawing]

[0017] [Figure 1] This is a vertical cross-sectional view of a concrete structure to which the carbonation inhibitor and cement mortar of the embodiment have been applied. [Modes for carrying out the invention]

[0018] Hereinafter, the carbonation inhibitor, cement mortar, and concrete structure according to the 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 Figure 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. Further, the concrete structure 1 according to the embodiment is provided with the modified layer 13 formed from the carbonation inhibitor on the inner surface side, and the protective layer 15 formed from cement mortar on the outer surface side, whereby carbonation prevention can be appropriately achieved.

[0019] The carbonation inhibitor of the embodiment forming the modified layer 13 contains sodium silicate (water glass), sodium hydroxide, and dilution water, and has a molar ratio (SiO2 / Na2O) specified in JIS K 1408:1966 (Sodium silicate (Sodium silicate solution)) of 2.5 or less.

[0020] When the carbonation inhibitor is applied to the concrete 11, sodium ions (sodium oxide (Na2O)) of the carbonation inhibitor penetrate into the concrete 11 to exert the carbonation prevention function. In addition, silicate ion micelles eluted from silicon dioxide of sodium silicate combine with calcium in the concrete 11 to form calcium silicate that closes the pores on the surface of the concrete 11, so that the penetration of carbonation accelerating components such as carbon dioxide and acid rain into the concrete 11 is suppressed.

[0021] The inventors of the present application have found that the anti-carbonation agent can be applied by spray coating when the molar ratio (SiO₂ / Na₂O) of the anti-carbonation agent is 2.5 or less. When the molar ratio is 2.5 or less, the anti-carbonation agent chemically stabilizes silicon dioxide (SiO₂), which lacks chemical stability, by dissolving it with sodium ions, thus enabling application by spray coating. If the molar ratio of the anti-carbonation agent exceeds 2.5, silicon dioxide lacks chemical stability, and during spray coating, silicon dioxide may precipitate at the discharge port of the spray gun, causing clogging. As 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, although application by spray coating is possible, since sodium ions (sodium oxide) are contained in excess, the sodium ions may re-dissolve the calcium silicate that fills the pores on the surface of the concrete 11, and the sufficient anti-carbonation effect may not be obtained. In yet another embodiment, the molar ratio of the anti-carbonation agent can be 1.85 to 2.25.

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

[0023] In the embodiment, the carbonation inhibitor can contain 8 to 14% by mass of silicon dioxide. This is because it can effectively prevent carbonation of concrete 11 that has a modified layer 13 formed from the carbonation inhibitor after application. If the silicon dioxide content is less than 8% by mass, the total amount of silicon dioxide contained in the carbonation inhibitor is small, and it may not be able to sufficiently block the pores on the surface of the concrete 11. On the other hand, if the silicon dioxide content exceeds 14% by mass, depending on the molar ratio, the sodium oxide content may become relatively high, and the water resistance of the modified layer 13 formed from the carbonation inhibitor may be poor. In another embodiment, the silicon dioxide content of the carbonation inhibitor can be 9 to 13% by mass, and in yet another embodiment, it can be 9.5 to 12% by mass.

[0024] The neutralization inhibitor in this embodiment can be prepared by adding sodium hydroxide and diluting water as appropriate to sodium silicate (water glass).

[0025] Furthermore, the neutralization inhibitor in this embodiment may contain a synthetic resin emulsion. By including a synthetic resin emulsion, the modified layer 13 formed from the neutralization inhibitor can have enhanced water resistance. As the synthetic resin constituting the synthetic resin emulsion, acrylic resin, vinyl acetate resin, vinyl versatate resin, ethylene vinyl acetate copolymer resin, styrene-butadiene resin, etc., can be used. In another embodiment, the neutralization inhibitor may contain a styrene-butadiene resin emulsion, which can further enhance water resistance.

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

[0027] The main component of cement mortar powder specifically contains cement, re-emulsifiable powdered resin (synthetic resin), and aggregate, and may contain thickeners, fibers, and termite repellents as needed. These are all powdered raw materials, and the main component of cement mortar powder can be produced by mixing them using a powder mixer such as a Nauter mixer or paddle mixer.

[0028] Cement is a material that hardens by combining with water, and ordinary Portland cement as defined in Portland cement (JIS R 5210-2019) can be suitably used. Other types of cement can also be used in the cement mortar, as long as they do not hinder the effects of the present invention. Other types of cement 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 granular state, and it re-emulsifies when water is added and stirred. By incorporating re-emulsifiable powder resin into cement mortar, it can enhance the water resistance of the protective layer 15 formed from the cement mortar, and also impart flexibility to the protective layer 15, allowing it to follow the expansion and contraction of the concrete 11. For this reason, it is suitable for application to the outer surface of concrete structures that are exposed to rainwater, etc. (Figure 1). Re-emulsifiable powder resin can be used as specified in the Cement Admixture Polymer Dispersion and Re-emulsifiable Powder Resin (JIS A 6203:2015), and commercially available re-emulsifiable powder resins such as Movinyl Powder (manufactured by Japan Coating Resin Co., Ltd.), Sumikaflex (Sumika Chemtex Co., Ltd.), Acronal (manufactured by BASF Ltd.), and ELOTEX (Ceranese Japan Co., Ltd.) can be used. In the cement mortar of the embodiment, the amount of re-emulsifiable powder resin added 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 amount of re-emulsifiable powder resin added 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 it exceeds 100 parts by mass per 100 parts by mass of cement, the water resistance of the protective layer 15 may be poor because the re-emulsifiable powder resin contains many water-affinity components. In another embodiment, the amount of re-emulsifiable powder resin added can be 30 to 80 parts by mass per 100 parts by mass of cement, and in yet another embodiment, it can be 40 to 60 parts by mass. In the case of a two-component cement mortar, the amount of re-emulsifiable powder resin added is 5 to 100 parts by mass per 100 parts by mass of cement, in another embodiment, it can be 10 to 80 parts by mass, and in yet another embodiment, it can be 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 also acting as a bulking agent to reduce raw material costs. Suitable aggregates for the cement mortar in this embodiment include silica sand, crushed limestone (crushed limestone), and other materials. In another embodiment, silica sand can be used. In the cement mortar of this embodiment, the amount of aggregate is 50 to 800 parts by mass per 100 parts by mass of cement. If the amount of aggregate 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 it exceeds 800 parts by mass per 100 parts by mass of cement, the strength of the protective layer 15 may be inferior because there is less binder (cement, synthetic resin) relative to the aggregate. In another embodiment, the amount of aggregate can be 100 to 600 parts by mass per 100 parts by mass of cement, and in yet another embodiment, it can be 200 to 400 parts by mass.

[0031] In this embodiment, the aggregate may contain 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 (JIS Z 8801-1:2019), and at least 20% by mass of fine particles that pass through a metal mesh sieve with a nominal mesh opening of 180 μm. This combination of coarse and fine particles makes the protective layer 15 formed from the cement mortar denser, thereby improving the water resistance of the protective layer 15. In another embodiment, the aggregate may contain at least 40% 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 30% by mass of fine particles that pass through a metal mesh sieve with a nominal mesh opening of 180 μm.

[0032] Thickening agents are materials added to cement mortar during application to adjust its workability and prevent sagging. As thickening agents, methylcellulose (MC), hydroxyethylcellulose (HEC), hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), etc., can be selected and added as appropriate.

[0033] Fibers are added to cement mortar during application to improve workability and prevent sagging. Synthetic resin fibers, glass fibers, and other types of fibers can be selected as appropriate.

[0034] Termite repellents are additives that repel ants, and as termite repellents, pyrethroid compounds such as acrinatrin, 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-thiazole-5-ylmethyl)-3-methyl-2-nitroguanidine or 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidine-2-yridenamine can be used. These termite repellents are preferably coated with a synthetic resin and in powder form. In particular, coating the termite repellent with a synthetic resin can suppress inactivation by alkaline cement mortar and concrete carbonation inhibitors.

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

[0036] Commercially available synthetic resin emulsions with cement admixture properties can be used. Suitable commercially available synthetic resin emulsions include Polytron (manufactured by Asahi Kasei Corporation), Pegar (manufactured by High Pressure Gas Industry Co., Ltd.), and Acronal (manufactured by BASF Ltd.), which can be selected and used as appropriate.

[0037] Water also acts as the mixing water for cement. Therefore, if the mixing water for cement can be supplied by the water contained in the synthetic resin emulsion, it can be omitted.

[0038] The defoaming agent suppresses foaming of the cement mortar mixture, and commercially available products can be used as appropriate. The thickening agent suppresses sedimentation and separation of the cement mortar mixture, and commercially available products can be used as appropriate. The preservative suppresses spoilage of the cement mortar mixture, and commercially available products can be used as appropriate. The pH adjuster adjusts the pH of the cement mortar mixture and suppresses sedimentation 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 concrete structures 1 such as concrete foundations (raft foundations, strip foundations), reinforced concrete buildings, reinforced concrete structures, and bridge substructures (abutments, piers).

[0040] Next, the method for applying the carbonation inhibitor and cement mortar according to the embodiment will be explained using the application to a raft foundation as an example, as shown in Figure 1.

[0041] The neutralization inhibitor is applied to the concrete foundation (slab foundation) after concrete pouring and demolding, using a spray painter such as a battery-powered sprayer or a manual sprayer. Since these spray painters do not require a power source or special equipment, they can be used on any concrete structure 1, even if a power source is not available, without limiting the application area. The spray pressure of these spray painters is 0.3 to 1.5 MPa.

[0042] During painting, the carbonation inhibitor has a molar ratio of 2.5 or less, so it does not clog the nozzle of the sprayer. Because spray painting is possible, the carbonation inhibitor can be applied faster compared to other painting methods (such as roller painting or brush painting). When the carbonation inhibitor is applied, a modified layer 13 with carbonation-preventing properties is formed on the slab foundation (concrete 11).

[0043] As shown in Figure 1, the areas to be treated (painted) with the carbonation inhibitor are the inner surfaces of the slab foundation, excluding the outer surfaces. This is because the inner surfaces are less exposed to rainwater, etc., once the building is constructed. To prevent any unpainted areas, the treatment can extend up to the upper edge of the outer surface of the slab foundation.

[0044] After applying the carbonation inhibitor, cement mortar is applied, but the cement mortar application can be done after the building is constructed, excluding the interior. The cement mortar is applied to the outer surface of the slab foundation, within an area that can be visually inspected, 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 trowel that can ensure sufficient coating thickness. In this embodiment, a porous roller was used as the roller for applying the cement mortar. When the cement mortar is applied, a protective layer 15 with carbonation inhibitory function 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] In the concrete structure 1 formed in this manner, the alkalinity of the modified layer 13 made of sodium silicate provides a neutralization prevention function on the inner surface. On the outer surface, the cement contained in the protective layer 15 made of cement mortar provides a neutralization prevention function, and the combination of aggregate particle sizes and the dispersion of synthetic resin provide water resistance. [Examples]

[0046] For the embodiment, the neutralization inhibitors with different compositions were evaluated by performing the sprayability test and neutralization inhibitory test described below.

[0047] Atomization test The spray performance test was conducted by injecting 4 liters of neutralization inhibitor into a 5 liter tank capacity sprayer (battery-operated sprayer IR-N5000 (manufactured by Iris Ohyama Co., Ltd.)) and continuously spraying the 4 liters of neutralization inhibitor. The test results were evaluated as follows: ○ if all 4 liters of neutralization inhibitor could be sprayed without nozzle clogging, △ if all 4 liters could be sprayed but nozzle clogging occurred and the discharge volume changed, and × if nozzle clogging occurred and all 4 liters could not be sprayed.

[0048] Neutralization prevention test For the carbonation prevention test, the test specimen consisted of a 40 x 40 x 160 mm cement mortar (cement:sand = 1:3) with 100 g / m² of carbonation inhibitor applied to all six sides. 2 The coating was applied using the specified amount to create the test specimens. For the neutralization prevention test, the test specimens were exposed outdoors for six months, split along the longitudinal center in the transverse direction, and a phenolphthalein solution (1%) was sprayed onto the cross-section. The neutralization depth at which the color did not change to purple was then measured. The test results were evaluated as follows: ○ for a neutralization depth of 1 mm or less, △ for a neutralization depth between 1 mm and 3 mm, and × for a neutralization depth exceeding 3 mm.

[0049] Table 1 shows examples of tests for neutralization inhibitors. Examples 1-6, 9, and 10 are examples, while examples 7 and 8 are comparative examples.

[0050] [Table 1]

[0051] (Test examples 1-6) Test examples 1-6 are examples where the SiO2 / Na2O molar ratio of sodium silicate is between 1.6 and 2.5. In test examples 1-6, the SiO2 / Na2O molar ratio is 2.5 or less, so in the sprayability test, the entire 4L could be sprayed without nozzle clogging, and since the molar ratio is 1.6 or higher, the neutralization prevention performance was also sufficiently met. In test example 5, with a molar ratio of 1.86, the result of the neutralization prevention test was a "○", but it was close to the limit. Among these test examples, the best mode is test examples 1-4, and it is difficult to rank their performance, but if we had to choose one, it would be test example 1.

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

[0053] (Test examples 9, 10) Test examples 9 and 10 are examples where the SiO2 / Na2O molar ratio of sodium silicate was 1.65 and 1.60, respectively. In the sprayability test, test examples 9 and 10 were able to spray all 4L without nozzle clogging, but their neutralization prevention performance was somewhat inferior.

[0054] The cement mortars in the embodiments were evaluated by conducting the water resistance test described below and the carbonation prevention test described above for cement mortars with different compositions.

[0055] Water resistance test The water resistance test was conducted according to Method B of the water permeability test in JIS A 6909:2014 (Architectural Finishing Coatings). The test results were evaluated as follows: ○ for water permeability of 0.5 mL or less, △ for water permeability between 0.5 mL and 1.0 mL, and × for water permeability exceeding 1.0 mL.

[0056] Table 2 shows examples of cement mortar tests. Test examples 11-13 are examples, and test examples 14 and 15 are comparative examples. The particle size distribution of silica sand contained in the cement mortar is shown in Table 3, and the composition 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 single-component cement mortar containing 300 parts by mass of aggregate per 100 parts by mass of cement, thereby increasing the physical strength of the 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 mesh opening of 300 μm, and at least 20% by mass of fine particles that pass through a metal mesh sieve with a nominal mesh opening of 180 μm. Therefore, the combination of coarse and fine particles enhances the water resistance of the protective layer 15, and the water resistance of the protective layer 15 is further enhanced by the re-emulsified powder resin.

[0061] (Test examples 12, 13) Test examples 12 and 13 are two-component cement mortars, and because they contain 300 parts by mass of aggregate per 100 parts by mass of cement, the physical strength of the protective layer 15 is enhanced. 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 metal mesh sieve with a nominal mesh opening of 180 μm. Therefore, the water resistance of the protective layer 15 is enhanced by the combination of coarse and fine particles. In addition, the water resistance of the protective layer 15 in test examples 12 and 13 is further enhanced by the acrylic resin contained in the cement mortar admixture. Note that the particle size distribution of the aggregate differs between test example 12 and test example 13.

[0062] (Test examples 14, 15) Test examples 14 and 15 are variations of test examples 12 and 13 in which the aggregate particle size distribution has been further modified. In test example 14, the aggregate particle size distribution is such that less than 30% by mass consists of coarse particles that do not pass through a metal sieve with a nominal mesh opening of 300 μm. In test example 15, the aggregate particle size distribution is such that less than 20% by mass consists of fine particles that pass through a nominal mesh opening of 180 μm. As a result, test examples 14 and 15 exhibited inferior water resistance, and consequently, slightly inferior carbonation prevention properties. [Explanation of symbols]

[0063] 1...Concrete structure, 11...Concrete, 13...Modified layer, 15...Protective layer, 16...Coloring layer.

Claims

1. SiO as specified in sodium silicate (JIS K 1408:1966) 2 / Na 2 A modified layer, formed from a neutralization inhibitor containing sodium silicate with a molar ratio of O of 1.6 to 2.06 and a silicon dioxide concentration of 8 to 14% by mass, is provided on the inner surface, excluding the outer surface of the rising portion. A protective layer formed from cement mortar is provided on the outer surface side of the rising portion, 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 pass through a metal mesh sieve (JIS Z 8801-1:2019) with a nominal mesh opening of 180 μm. A concrete foundation structure characterized by the following features.

2. SiO as specified in sodium silicate (JIS K 1408:1966) 2 / Na 2 A neutralization inhibitor containing sodium silicate, with a molar ratio of O of 1.6 to 2.06 and a silicon dioxide concentration of 8 to 14% by mass, is applied to the inner surface of the rising portion, excluding the outer surface, using a battery-operated or manual sprayer. A cement mortar containing cement, synthetic resin, and aggregate, wherein at least 30% by mass of the aggregate particles does 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 metal mesh sieve (JIS Z 8801-1:2019) with a nominal mesh opening of 180 μm, is applied to the outer surface of the rising portion using a roller or trowel. A method for painting concrete foundation structures, characterized by the following features.

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