JP2008196024A - Permeable rust preventive for concrete structure, and method for subjecting steel inside concrete structure to rust prevention - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permeable rust preventive for a concrete structure used by being applied to the surface of concrete for suppressing deterioration in a steel inside an existing concrete structure caused by rust, and capable of sufficiently infiltrating components effective for rust prevention into the arranged position of steel such as a reinforcing rod inside the concrete. <P>SOLUTION: A permeable rust preventive for a concrete structure is composed of: 2,4,7,9-tetramethyl-5-decyne-4,7-diol; an ether type nonionic surfactant; a nitrite; and water, and whose pH is preferably ≥9. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention suppresses the deterioration of the concrete structure due to rust on the steel materials such as reinforcing bars disposed in the existing concrete structure with the passage of time (aging deterioration), and durability of the concrete structure It is a rust preventive agent used to improve the performance, and is applied to the concrete surface that forms the outer wall of the existing concrete structure and penetrates to the position of steel materials such as rebars placed inside the concrete structure. The present invention relates to a penetrating rust inhibitor and a method for rust prevention of a steel material inside a concrete structure using the rust inhibitor.

  A concrete structure such as reinforced concrete in which steel is embedded is deteriorated with age and the strength of the entire structure is reduced. Specifically, aging deterioration, including the neutralization of concrete, moisture and salt content easily penetrates into the concrete structure triggered by lack of concrete covering thickness on the reinforcing bars etc. and cracks in the concrete, It is generated by generating rust on steel materials such as reinforcing bars and steel frames inside a concrete structure. When rust is generated in the steel material and the steel material is corroded, the volume of the steel material is apparently expanded, expansion pressure is applied to the concrete around the steel material, and cracks of the concrete increase from the inside of the concrete structure. As the aging deterioration further proceeds, the strength of the concrete structure as a whole further decreases, and eventually the concrete structure itself is destroyed. Therefore, when corrosion due to rust occurs in the steel material of the existing concrete structure, it is important to repair the steel material, and further, to prevent rust from occurring as much as possible in the steel material.

  Conventionally, as a method of repairing existing concrete structures and rust prevention treatment of reinforcing bars, nitrite aqueous solution or silicate aqueous solution is applied to the surface of the concrete structure, and nitrite or silicate which is a component of these aqueous solutions is applied to the concrete structure A method for suppressing deterioration over time by penetrating the inside is known. This rust prevention treatment method applies a nitrite aqueous solution (calcium nitrite aqueous solution or lithium nitrite aqueous solution) to the concrete surface that forms the outer wall of the concrete structure, and permeates and diffuses nitrite ions in the concrete to reinforce the reinforcing bars inside the concrete. It is a method of suppressing deterioration of an existing concrete structure due to rust by forming a passive film on the surface of the steel to suppress contact of moisture, salt, etc. to the steel material in a rust-proof environment (Patent Documents 1 and 2). , 3).

  Further, as a rust inhibitor used in such a rust prevention treatment method, a nitrite aqueous solution containing a surfactant or the like has been proposed. For example, Patent Document 4 discloses a rust inhibitor containing a nonionic surfactant such as polyoxyethylene alkyl, dioctyl sodium sulfosuccinate as an anionic surfactant, and glycerin. Further, Patent Document 5 discloses a rust inhibitor containing an alkane sulfonate, a dialkyl salt of sulfosuccinate and / or a polyoxyethylene alkyl ether. These are so-called penetrating rust preventives that allow nitrite ions to permeate into the concrete structure to obtain a rust-preventing effect. By incorporating a surfactant, nitrite penetrates into the concrete structure. It is a penetrating rust inhibitor for concrete structures which is intended to further improve the properties.

JP 60-108385 A JP-A-60-231478 JP-A-1-298185 JP 2002-371388 A JP-A-2005-76038

  In the conventional method of applying nitrite aqueous solution or silicate aqueous solution to the surface of concrete structure and applying rust prevention treatment to the steel material inside the existing concrete structure, there are components that exhibit rust prevention effect such as nitrite and silicate. The amount and depth did not penetrate sufficiently into the concrete structure, and even when the nitrite aqueous solution and silicate aqueous solution were further applied, the penetration amount and penetration depth of these components were insufficient. .

  For example, in the case of a building structure, a reinforcing bar embedded in a reinforced concrete structure is arranged at a position where the depth from the surface (cover thickness) is about 30 mm, and in the case of a civil engineering structure, the cover thickness is 30 to 60 mm. That is normal. And until the position of the reinforcing bar in such a concrete structure, the nitrite aqueous solution and the silicate aqueous solution used in the past could not sufficiently infiltrate nitrite ions.

  Although the permeable rust preventive agent described in Patent Document 4 is used in an aqueous solution, the aqueous solution is alkaline because it tends to cause chemical decomposition of nitrite when it is weakly alkaline or acidic at pH less than 9.0. (PH 9.0-12.5) needs to be used. In this respect, since the ester bond part of dioctyl sodium sulfosuccinate as an anionic surfactant blended in this permeable rust preventive is hydrolyzed under alkalinity, its function as a surfactant is gradually lost. Resulting in. For this reason, this penetrable rust preventive cannot stably function as a surfactant that allows nitrite ions to penetrate efficiently into the concrete, and the rust preventive does not reach the position of the steel material inside the concrete structure. Nitrate ions could not be sufficiently penetrated.

  As for the permeable rust preventive agent described in Patent Document 5, as in the case of the permeable rust preventive agent described in Patent Document 4, the ester bond portion of the dialkylsulfosuccinate serving as the surfactant to be blended is subjected to alkaline hydrolysis. However, there has been a problem that the function as a surfactant is gradually lost.

  Moreover, in the permeable rust preventive agent described in Patent Document 5, the alkane sulfonate as an anionic surfactant constituting an essential component of the permeable rust preventive agent is used for an aqueous electrolyte solution containing nitrite in a high concentration. Even if a predetermined amount is added, since the high-concentration aqueous solution of nitrite and the alkane sulfonate are poorly compatible, the alkane sulfonate is hardly dissolved in the nitrite aqueous solution and becomes suspended in the aqueous solution. . In particular, when sodium alkane sulfonate is blended with a high concentration aqueous solution of nitrite, for example, 15-20% by mass of calcium nitrite, sodium alkane sulfonate is ion-exchanged between sodium ions and calcium ions in the aqueous solution. As a result, the substance becomes hardly soluble in water (calcium alkane sulfonate), and the alkane sulfonate cannot function itself as a surfactant. Then, even if this permeable rust preventive was applied to the concrete surface, calcium alkanesulfonate that did not dissolve in water was deposited on the concrete surface layer, not only acting as a surfactant, but also nitrite ions There was also a problem that the penetration into the concrete structure was hindered. For these reasons, this penetrable rust preventive could not provide sufficient penetrability of nitrite ions into the concrete structure.

  In addition, a polyoxyethylene alkyl ether type nonionic surfactant and an anionic surfactant are used in combination, and a polyoxyethylene alkyl ether type nonionic surfactant can be used alone without forming a penetrating rust inhibitor. It is also possible to construct a permeable rust inhibitor by configuring the permeable rust preventive and increasing the blending ratio of the nonionic surfactant, but when configured in this way, a nitrite ion concrete structure There was a limit to the permeability to the inside, and sufficient permeability could not be obtained. On the contrary, by increasing the compounding ratio of nonionic surfactant in the penetrating rust preventive agent, when the penetrating rust preventive agent is applied to the concrete wall with a brush or roller, it foams violently and wets the concrete wall. As a result, the problem of adversely affecting the permeability of nitrite ions occurs.

  The present invention is a permeable rust preventive that is applied to the surface of an existing concrete structure and is effectively used for performing a rust preventive treatment that prevents aging deterioration of the concrete. It is possible to fully penetrate the rust component up to the location of the steel material such as rebar inside the concrete structure, and to effectively prevent the rust-proofing of the steel material inside the concrete structure. An object of the present invention is to provide a method for rust-proofing a steel material inside a concrete structure while providing an anti-corrosive agent.

  The present invention is characterized by comprising (1) 2,4,7,9-tetramethyl-5-decyne-4,7-diol, an ether type nonionic surfactant, nitrite, and water. (2) 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether-type nonionic surfactant, dissolved in nitrite in water (3) 2,4,7,9-tetramethyl-5-decyne-4, a permeable rust inhibitor for concrete structures according to the above (1), characterized in that it is blended in a nitrite solution. 7-diol is contained in an amount of 0.005 to 2 mass%, an ether type nonionic surfactant is contained in an amount of 0.05 to 5 mass%, and nitrite is contained in an amount of 1 to 40 mass%. 2) Penetration rust preventive for concrete structures according to 2), (4) Ate The permeable rust preventive for concrete structures according to any one of (1) to (3), wherein the non-ionic surfactant is a secondary higher alcohol ethoxylate, (5) nitrite Is a calcium nitrite or lithium nitrite, and has a pH of 9 or more, the permeable rust preventive for concrete structures according to any one of (1) to (4) above, (6 ) After applying the permeable rust inhibitor for a concrete structure according to any one of (1) to (5) above to the surface of the concrete structure in which steel is embedded, the surface of the concrete structure A gist is a method of rust-proofing a steel material inside a concrete structure, characterized in that a silicate aqueous solution is applied to the steel structure.

  The permeable rust preventive for concrete structures according to the present invention (permeable rust preventive) includes nitrite and water, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether. In combination with a type nonionic surfactant, when this permeable rust inhibitor for concrete is applied to the surface of an existing concrete structure, nitrite ions, which constitute a rust preventive component, permeate and diffuse into the concrete structure. In addition to being excellent in performance, the depth of penetration of nitrite ions into the concrete structure has also been greatly improved, and nitrite is sufficiently sufficient to reach the position of the reinforcing bar (cover thickness around 30 mm) in the concrete structure. There is an effect that ions can permeate and diffuse.

  Moreover, according to this permeable anticorrosive agent, nitrite is added to water in advance to make an aqueous nitrite solution, and then 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether Adding nitrite after adding 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether type nonionic surfactant to water by adding nonionic surfactant , More efficient addition of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether-type nonionic surfactant, and efficiently dissolves nitrite in water be able to.

  In addition, the permeable rust preventive agent of the present invention has very good wettability with respect to the concrete surface compared to the conventional permeable rust preventive agent. It is excellent, and when it is applied to the wall surface (vertical surface) or ceiling surface of an existing concrete structure, the possibility that this permeable rust preventive agent will flow down can be suppressed.

  In the present invention, 2,4,7,9-tetramethyl-5-decyne-4,7-diol can be used as a nonionic surfactant, and this surfactant is combined with an ether type nonionic surfactant. By using together, it is possible to obtain an effect of improving diffusibility of nitrite ions into the concrete structure.

  2,4,7,9-Tetramethyl-5-decyne-4,7-diol is inherently poorly soluble in water, and by itself, a sufficient amount can be stably dissolved and / or emulsified in water. Therefore, it is difficult to improve the penetration of nitrite ions into the concrete in the penetrating rust inhibitor. In the permeable rust preventive of the present invention, an ether type nonionic surfactant is used in combination, and a sufficient amount of 2,4,7,9-tetramethyl-5-decyne-4,7-diol is added to water. Since it can be stably solubilized and / or emulsified, the permeability of nitrite ions in the permeable rust preventive can be remarkably improved. Moreover, since 2,4,7,9-tetramethyl-5-decyne-4,7-diol can improve antifoaming properties, an ether type nonionic surfactant is added to the permeable rust inhibitor. The use of 2,4,7,9-tetramethyl-5-decyne-4,7-diol can significantly reduce the rust-proofing of concrete surfaces. It is preferable also from an implementation.

  Thus, according to the permeable rust preventive agent of the present invention, by using 2,4,7,9-tetramethyl-5-decyne-4,7-diol and an ether type nonionic surfactant together, When each compound is used independently, it produces a unique effect that cannot be conceived and produces a synergistic effect.

  Moreover, according to the permeable rust preventive agent of this invention, even if the density | concentration of nitrite is made as high as 10-40 mass%, the permeability improvement function of the nitrite ion by surfactant can be hold | maintained.

  According to the present invention, the nitrite ions in the permeable rust preventive agent are located inside the concrete by simply applying the permeable rust preventive agent for concrete of the present invention to the surface of the existing concrete structure. Since the steel bars can be sufficiently infiltrated into the reinforcing bars, the rust prevention of the concrete structure can be maintained over a long period of time, and the aging deterioration can be delayed. That is, according to the present invention, the durability of the concrete structure can be effectively improved, and the concrete structure can be maintained for a long time.

  The known penetrable rust preventives containing both nonionic surfactants and anionic surfactants as described above, when applied to the concrete surface, there are many problems of permeability, foaming, and wettability (this In the specification, the wettability is a concept that collectively refers to wetting, spreading, wetting, and penetration. In this respect, in order to reduce foaming and improve wettability, it is conceivable to add an antifoaming agent such as a silicone-based antifoaming agent to the permeable rust preventive. However, in such a case, a repellency phenomenon may occur instead of foaming, and the wettability may eventually deteriorate. Not only that, even if you try to apply cement mortar or paint coating after applying a permeable rust inhibitor to the concrete surface, it may even cause problems such as the cement mortar not being able to adhere well to the concrete structure. It may end up. According to the present invention, it is possible to obtain a permeable rust preventive having excellent wettability without causing such problems.

  In the present invention, the ether type nonionic surfactant has good solubility in an aqueous nitrite solution and can exist more stably in an alkaline aqueous solution. Therefore, the influence of the alkali component or salt normally contained in the concrete structure is exerted. It is possible to obtain a permeable rust preventive for concrete that is further excellent in permeability of nitrite ions to a concrete structure while suppressing. In addition, ether type nonionic surfactants usually have a large ability to lower the surface tension in aqueous solutions, and also have a large ability to solubilize and / or emulsify highly hydrophobic surfactants in aqueous solutions. Convenient for combined use with poorly soluble surfactants.

  In the present invention, a secondary higher alcohol ethoxylate is used as an ether type nonionic surfactant among the polyoxyethylene alkyl ethers, and a primary higher alcohol ethoxylate is used as the ether type nonionic surfactant. It is possible to obtain a permeable rust preventive for concrete which is more excellent in nitrite ion permeability into a concrete structure.

  In the present invention, by setting the pH of the permeable anticorrosive agent for concrete to 9 or more, it becomes easy to make the steel material inside the concrete structure under a high pH condition around the steel material, that is, in an alkaline atmosphere. It becomes easy to suppress the occurrence of rust and the progress of corrosion of the steel material due to rust. Moreover, nitrite ion can be stabilized by making the permeable rust preventive agent for concrete alkaline.

  The permeable rust preventive agent for concrete structures of the present invention can be applied to the surface of a concrete structure in which a steel material is disposed, thereby being used in a method for rust-proofing a steel material inside a concrete structure. it can.

  In addition, the method of rust-proofing the steel material inside the concrete structure is not only to apply the permeable rust preventive agent for the concrete structure of the present invention to the surface of the concrete structure in which the steel material is disposed, Application of a silicate aqueous solution to the surface of a concrete structure may be performed in combination.

  Further, in the method of rust-proofing the steel material inside the concrete structure, after applying the permeable rust preventive agent for the concrete structure of the present invention to the surface of the concrete structure in which the steel material is disposed, It is preferable to apply a silicate aqueous solution to the surface of the concrete structure. By applying a silicate aqueous solution after applying the permeable rust preventive agent for concrete structures of the present invention, not only the effect of suppressing the entry of new salts from the outside to the inside of the concrete structure but also the concrete structure There is an effect of suppressing the nitrite ions that have permeated into the surface of the concrete structure again, and the durability of the concrete structure is effectively improved.

  The permeable rust preventive for concrete structures of the present invention comprises 2,4,7,9-tetramethyl-5-decyne-4,7-diol, an ether type nonionic surfactant, nitrite and water.

  2,4,7,9-Tetramethyl-5-decyne-4,7-diol is a nonionic surfactant having a triple bond in its molecular structure. More specifically, it is represented by the following (Chemical Formula 1). Acetylene glycol-based compound.

  2,4,7,9-Tetramethyl-5-decyne-4,7-diol is a compound that combines wettability, defoaming properties, and orientation to metal (rebar), ie, the liquid to be added. It is a compound that has both a function of improving wettability and a function of improving antifoaming properties and is commercially available.

  Here, in order to improve the wettability of the liquid, it is important to reduce the surface tension of the liquid, and the surface tension measurement is an indicator of the wettability. The liquid in a stationary (static) state is usually used by applying a liquid that forms a permeable rust inhibitor to the concrete surface of a concrete structure using a roller or brush. In addition to the surface tension of the liquid, the interface between the liquid and air is completed one after another (dynamic) (ie, new interfaces are formed one after another when applied to the concrete wall or ceiling surface with a brush or roller. It is important to measure the surface tension of the liquid in the developing state. If the surface tension of the liquid in this dynamic state (dynamic surface tension) is suppressed to a small value, surface defects such as repellency are less likely to occur even if the interface is quickly formed.

  With regard to dynamic surface tension, dynamic surface tension is generated by generating bubbles in a liquid whose dynamic surface tension is to be measured at a predetermined generation rate (generation period) and measuring the pressure applied to the bubbles from the liquid. It can measure concretely by using the measuring method (maximum bubble pressure method). For the measurement of the maximum bubble pressure method, a commercially available dynamic surface tension meter can be appropriately used as a measuring device. For example, a portable dynamic surface tension meter Theta (manufactured by Eihiro Seiki Co., Ltd.) can be specifically mentioned. .

  2,4,7,9-Tetramethyl-5-decyne-4,7-diol used in the present invention is excellent in the effect of reducing the dynamic surface tension as described above. This is specifically shown in Table 1 by measuring the dynamic surface tension of 2,4,7,9-tetramethyl-5-decyne-4,7-diol by the maximum bubble pressure method. it can.

注）表中、気泡周波数は、単位時間当たり発生させた泡の数を示す。また、静的状態の液体における表面張力は気泡周波数が１Ｈｚである場合の表面張力で評価され、動的状態の液体における表面張力（動的表面張力）は気泡周波数が６Ｈｚである場合の表面張力で評価される。 (Table 1)

Note) In the table, the bubble frequency indicates the number of bubbles generated per unit time. Further, the surface tension in the static liquid is evaluated by the surface tension when the bubble frequency is 1 Hz, and the surface tension (dynamic surface tension) in the dynamic liquid is the surface tension when the bubble frequency is 6 Hz. It is evaluated with.

  In Table 1, the sample solution for 2,4,7,9-tetramethyl-5-decyne-4,7-diol is 2,4,7,9-tetramethyl-5-decyne-4. A 0.1% by mass aqueous solution of 7-diol (HLB3.5) is used, and a sample liquid for a commercially available ether type nonionic activator is a 0.1% by mass aqueous solution of polyoxyethylene lauryl ether (HLB 13.5). Was used.

  According to Table 1, the dynamic surface tension of water is 2,4,7,9-tetramethyl-5-decyne-4,7-diol, rather than when a commercial ether type nonionic activator is incorporated into water. It is confirmed that the value becomes smaller when is mixed with water.

  The penetrating rust inhibitor of the present invention includes 2,4,7,9-tetramethyl-5-decyne-4,7-diol and a nonionic surfactant (2,4,7,9-tetramethyl-5-decyne). -4,7-diol is excluded). Among the surfactants, the nonionic surfactant is used because of the following points. First, as the surfactant to be added to the permeable rust preventive, it is preferable to select a surfactant that can be used by being blended with a nitrite aqueous solution having a wide nitrite concentration. That is, a surfactant that can be used even in a high concentration aqueous electrolyte solution in which the nitrite contained in the permeable rust preventive is dissolved in water at a high concentration of 15 to 25% by mass is preferable. Second, since the aqueous nitrite solution is usually used in an alkaline aqueous solution having a pH of 9.0 to 12.0, the surfactant is preferably stable in the alkaline aqueous solution. A nonionic surfactant is preferably selected as a good one in terms of both solubility in a high-concentration electrolyte aqueous solution as the first point and stability under alkaline conditions as the second point.

  Furthermore, among nonionic surfactants, ether type nonionic surfactants have a large ability to reduce surface tension in water, and can suppress the risk of excessive foaming (medium foaming property). Is preferred. The ether type nonionic surfactant is more suitable from the viewpoint that it is not easily affected by alkali components, salts and other ions in the concrete.

  Specific examples of the ether type nonionic surfactant include alkyloxy group-containing polyalkylene oxides, alkenyloxy group-containing polyalkylene oxides, and alkynyloxy group-containing polyalkylene oxides. In addition, two or more types can be used in combination, for example, a combination of an alkyloxy group-containing polyalkylene oxide and an alkenyloxy group-containing polyalkylene oxide.

  Examples of the alkyloxy group-containing polyalkylene oxide used in the present invention include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene cetyl ether, polyoxypropylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, and the like. Ether type nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polyoxypropylene block copolymer, and the like can be used as appropriate, but polyoxyethylene alkyl ether is preferred. Examples of the alkenyloxy group-containing polyalkylene oxide include those in which a double bond is introduced into the alkyl group of the alkyloxy group-containing polyalkylene oxide as described above to form an alkenyl group, such as polyoxyethylene oleyl ether. Can do.

  The chemical structural formula of polyoxyethylene alkyl ether is represented by the following formula 1. In the present invention, the alkyl group (R) has 12 to 14 carbon atoms, and the number of added moles of ethylene oxide (n) is 7-12 are liquid at room temperature and have good solubility in water (and micelle solubility) (ie rich in hydrophilicity) and are easily blended in aqueous nitrite solution, and have excellent ability to reduce the surface tension of water. It is preferable from the viewpoint of good permeability. In the alkyl group (R), it does not matter whether an unsaturated bond (double bond) is present.

(Chemical formula 2)
_{RO- (CH 2 CH 2 O)} n -H ( Equation 1)

In the case of using polyoxyethylene alkyl ether in the present invention, it is preferable to use a secondary higher alcohol ethoxylate as shown in the following formula 2, and carbon in the alkyl group (R ₁ , R ₂ ). It is preferable that the total number is 11 to 13, the number of added moles of ethylene oxide (n) is 7 to 12, and the HLB (Hydrophile-lipophile balance) (hydrophilic / lipophilic balance) is 12 to 15. Secondary higher alcohol ethoxylates are superior to primary higher alcohol ethoxylates in their ability to improve the penetrating power of liquids (excellent in reducing surface tension) and have a low pour point (° C). It is suitable.

  The alkynyloxy group-containing polyalkylene oxide used in the present invention is a compound having a acetylene group which is a hydrophobic group and a polyalkylene oxide group which is a hydrophilic group in the molecular structure. As the alkynyloxy group-containing polyalkylene oxide, polyoxyethylene acetylenic glycol ether (polyethoxylate of acetylenic diol) having 8 to 12 ethylene oxide addition moles and 12 to 15 HLB is preferably used. Specifically, polyoxyethylene-2,4,7,9-tetramethyl-5-decyne-4,7-diol and the like can be mentioned.

  As the nitrite used in the permeable rust preventive of the present invention, calcium nitrite or lithium nitrite is preferably used. Sodium nitrite can also be used as nitrite, but after applying a permeable rust preventive to the concrete surface, there is an increased risk of whitening on the coated surface, compared to using calcium nitrite or lithium nitrite. It is not preferable for practical use.

  The water used in the present invention can be used even if it has a quality in which mineral ions are mixed to such an extent that the effects of the present invention are not hindered, but distilled water, ion-exchanged water, pure water or even ultrapure water. It is preferable that the quality is such as.

  In the penetrating rust inhibitor of the present invention, the blending ratio of 2,4,7,9-tetramethyl-5-decyne-4,7-diol is 0.005 to 2% by mass, preferably 0.01 to 1% by mass. The mixing ratio of the ether type nonionic surfactant is 0.05 to 5% by mass, preferably 0.1 to 2% by mass, and the mixing ratio of nitrite is 1 to 40% by mass, preferably 10%. -40 mass%. However, the blending ratio indicates the ratio (mass%) when the total amount of the penetrating rust inhibitor is 100 mass%. Penetration when the blending ratio of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, ether type nonionic surfactant or nitrite is less than the minimum of the above blending ratios There is a possibility that the amount of nitrite ions penetrating the rust preventive agent from the surface of the concrete structure to the inside thereof becomes insufficient. If the blending ratio of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, ether type nonionic surfactant or nitrite exceeds the maximum of the above-mentioned blending ratios, Even if the respective blending amounts are increased, a dramatic improvement in the penetration amount of nitrite ions penetrating from the surface of the concrete structure into the interior cannot be expected, which is not preferable because the production cost of the penetrating rust inhibitor is high.

  The penetrating rust preventive agent of the present invention is preferably alkaline, and specifically has a pH of 9 or more. In order to adjust pH of a permeable rust preventive agent, it can implement | achieve concretely by adding a pH adjuster.

  Examples of the pH adjuster include alkali imparting agents, and examples of the alkalinity imparting agent include calcium hydroxide, lithium hydroxide, and potassium hydroxide.

  The permeable rust preventive of the present invention is produced by adding nitrite, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and an ether type nonionic surfactant to water and stirring. In addition, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and an ether type nonionic surfactant are added to an aqueous nitrite solution in which nitrite is dissolved in water. Can be manufactured.

  Regarding the addition of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ether type nonionic surfactant in obtaining penetrable rust preventive agent, after addition of ether type nonionic surfactant 2,4,7,9-Tetramethyl-5-decyne-4,7-diol is preferably added. A highly hydrophobic 2,4,7,9-tetramethyl-5 added later by adding an ether type nonionic surfactant to water or an aqueous nitrous acid solution and dissolving and / or emulsifying it first. -A decyne-4,7-diol can also be rapidly dissolved and / or emulsified. Therefore, it is more efficient to dissolve nitrite in water, add ether type nonionic surfactant, and then add 2,4,7,9-tetramethyl-5-decyne-4,7-diol It is preferable in that a penetrating rust preventive agent can be obtained.

  In preparing the permeable rust preventive of the present invention, 2,4,7,9-tetramethyl-5-decyne-4,7-diol was previously converted to ethylene glycol, propylene glycol, isopropanol, 2-ethylhexanol. Alternatively, a diluted solution may be prepared by diluting with a solvent such as butyl cellosolve, and the diluted solution may be added to the aqueous nitrite solution. By doing so, 2,4,7,9-tetramethyl-5-decyne-4,7-diol can be efficiently blended into the aqueous nitrite solution.

  In the penetrable rust preventive agent of the present invention, an appropriate amount of polyhydric alcohol such as ethylene glycol, propylene glycol, 1,3 butanediol, glycerin can be blended in addition to the blending component of the present invention. In this way, the wet effect can be effectively imparted to the permeable rust preventive agent, and the permeable rust preventive agent applied to the concrete surface improves the familiarity with the concrete surface, so that the interior of the concrete surface is better than the concrete surface. The possibility of drying before nitrite ions permeate can also be suppressed.

  In the penetrating rust preventive of the present invention, an anionic surfactant such as dialkylsulfosuccinate or an amphoteric surfactant exhibiting anionic property in an alkaline aqueous solution is blended within a range not impairing the function of the present invention. Also good.

  Further, in the penetrating rust preventive agent of the present invention, silicone antifoaming agents such as dimethylpolysiloxane, modified polysiloxane and other organopolysiloxanes and other antifoaming agents do not impair the function of the present invention. May be blended.

  The permeable rust preventive for concrete structures of the present invention is applied to the surface of a concrete structure having a steel material disposed therein, thereby being used in a method for rust-proofing the steel material inside the concrete structure.

  In addition, the method of rustproofing the steel material inside the concrete structure is not only applying the permeable rust preventive agent for the concrete structure of the present invention to the surface of the concrete structure in which the steel material is disposed inside, but also concrete. It may be carried out in combination with applying a silicate aqueous solution to the surface of the structure.

  When a silicate aqueous solution in which a silicate such as lithium silicate is dissolved in water is applied to the surface of a concrete structure in which steel is embedded, many fine gaps formed from the surface of the concrete structure to the inside are formed. Through this, alkaline ions such as lithium ions permeate and diffuse into the concrete structure, thereby making the inside of the concrete structure alkaline.

  Further, in the method of rust-proofing the steel material inside the concrete structure, after applying the permeable rust preventive agent for the concrete structure of the present invention to the surface of the concrete structure in which the steel material is disposed, It is preferable to apply a silicate aqueous solution to the surface of the concrete structure.

  This is because the silicate reacts with calcium hydroxide usually contained in the concrete structure to form a calcium silicate gel in the surface layer part from the concrete surface to the inside to a few millimeters and densify the surface part. By applying an aqueous rust inhibitor for concrete structures, and then applying a silicate aqueous solution, not only prevents the entry of salt from the outside to the inside of the concrete structure, but also penetrates into the concrete structure. There is an effect of suppressing nitrite ions from flowing out to the surface of the concrete structure again. Therefore, according to such a method of rust-proofing the steel material inside the concrete structure, the durability of the concrete structure is effectively improved. In addition, as a silicate aqueous solution, a commercially available thing can be selected suitably, Specifically, RV guard S aqueous solution (made by Tajima Roofing Co., Ltd.), RF-100 (made by Taiheiyo Material Co., Ltd.), Sabiran- P (made by Daito Co., Ltd.) etc. can be used.

  Next, the penetration rust preventive for existing concrete structures of the present invention will be further described using specific examples. However, the present invention is not limited to these examples.

Example 1
A mixed solution was prepared with 15 parts by mass of calcium nitrite, 0.06 parts by mass of calcium hydroxide as a pH adjusting agent, and 84.34 parts by mass of water, and 0.5 mass of polyoxyethylene lauryl ether was added to this mixed solution. To the composition 1 of Table 2, add 0.1 part by weight of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and stir and mix. A permeable rust inhibitor for concrete structures having a composition as shown was obtained. The pH of this permeable rust inhibitor for concrete structures was 11.3.

注）組成物１〜４のpH調整剤：水酸化カルシウム
組成物５〜６のpH調整剤：水酸化リチウム
ポリオキシエチレン第２級アルキルエーテルには、アルキル基炭素数12〜14の直鎖型
第２級高級アルコールエトキシレートを用いた。 (Table 2)

Note) pH adjuster for Compositions 1-4: Calcium hydroxide pH adjuster for Compositions 5-6: Lithium hydroxide Polyoxyethylene secondary alkyl ether has straight chain type alkyl group having 12-14 carbon atoms Secondary higher alcohol ethoxylate was used.

  Using the obtained permeable rust preventive for concrete structures, the osmotic diffusivity test and the foaming property test were performed as follows, and the osmotic diffusion property and foaming property inside the concrete structure were measured.

<Osmotic diffusion test>
First, a concrete structure specimen (concrete specimen) was prepared as follows.

A concrete blend was prepared, this concrete blend was cast into a cylindrical mold, and after demolding, sealing curing was performed for 2 weeks. Thereafter, curing was performed at a humidity of 80% and a temperature of 20 ° C. (28-day compressive strength: 26 N / mm ² ) to obtain a concrete specimen. The concrete specimen was obtained as a cylindrical specimen having a diameter of 10 cm and a height of 20 cm. In addition, about the prepared concrete compound, the compound composition is the unit cement amount: 300 kg / m ³ , fine aggregate + coarse aggregate: 1800 kg / m ³ , water cement ratio (W / C): 60%, fine Aggregate / (fine aggregate + coarse aggregate) ratio (s / a): 48%, slump: 18 cm, air amount: about 6.5%.

The moisture content in the obtained concrete specimen was adjusted to 4 to 6% in advance, and a permeable rust inhibitor for concrete structures was applied to the upper surface of the concrete specimen (the upper surface of the cylindrical body) at 800 ml / m. ² and left in a room maintained at a temperature of 20 ° C. and a relative humidity of 80% for 3 months, and then the penetration depth and penetration amount of nitrite ions were measured. The penetration depth / penetration amount of nitrite ions in the concrete specimens after standing for 3 months was measured by the following “method of analyzing nitrite ions”.

<Nitrite ion analysis method>
A test piece having a thickness of 10 mm is made by cutting the test piece every 10 mm in the depth direction from a position of 15 mm depth (penetration depth) from the coated surface of the concrete test piece, and nitrite ions contained in each test piece The concentration of was measured. The concentration of nitrite ions is measured as the nitrite ion content indicating how much nitrite ions are contained with respect to the water contained in the concrete. Measurement of the concentration of nitrite ions contained in each test piece is obtained by pulverizing each test piece to obtain a pulverized product, adding pure water to this pulverized product and dissolving and extracting all nitrite ions in water, The insoluble matter was filtered off, the filtrate was collected, and nitrite ions contained in the filtrate were measured by ion chromatography. The weight of nitrite ions contained in each test piece was measured by ion chromatography, and the nitrite ion content (ppm) with respect to the water contained in the concrete was calculated. The measurement results of the nitrite ion content are shown in Table 3.

<Foamability test>
200 g of the obtained permeable rust preventive agent for concrete structures was accommodated in a transparent plastic bottle (capacity 500 ml) previously provided with a scale indicating the length in the height direction. Shake up and down 10 times. Subsequently, the height (bubble height) (mm) of the foam layer formed on the liquid surface was measured at each time point immediately after shaking, 5 minutes, 60 minutes, and 120 minutes. The measurement was carried out twice for each time point, and the average value of the obtained measurement values was taken as the bubble height. The results of the foamability test are shown in Table 8.

注）浸透深さは、コンクリート試験体塗布面からの深さである。
(Table 3)

Note) Penetration depth is the depth from the concrete specimen application surface.

Examples 2-6
As in Example 1, permeable anticorrosive agents for concrete structures having the compositions shown in Compositions 2 to 6 in Table 2 were obtained (corresponding relationship between Examples 2 to 6 and Compositions 2 to 6). Are shown in Table 3). Moreover, about the obtained rust preventive agent for concrete, it carried out similarly to Example 1, and measured the penetration depth of the nitrite ion to each concrete test body. Moreover, about Example 3, 4, it implemented also about the foamability test. The results are shown in Tables 3 and 8.

Comparative Examples 1-7
Compositions 7 to 13 having the composition as shown in Tables 4 and 5 were obtained. For each of the obtained compositions 7 to 13, in the same manner as in Example 1, the penetration depth and penetration amount of nitrite ions into the concrete specimen when 800 ml / m ^{2 was} applied to the concrete specimen were measured. . For Comparative Examples 3, 4, 5, and 7, foaming tests were also performed. The results are shown in Tables 6, 7, and 8.

(Table 4)

(Table 5)

(Table 6)

(Table 7)

(Table 8)

  As described above, the position of the reinforcing bar in the reinforced concrete is usually present at a depth of about 30 mm from the concrete surface. As shown in Table 3 above, in the permeable rust preventive for concrete structures of the present invention, only nitrite ions have reached the depth of 50 mm beyond the depth of 30 mm from the concrete surface. In addition, nitrite ions have reached a position where the depth is 60 mm.

  Moreover, as shown in Table 3, Table 5, and 6, to the concrete structure inside at the time of using the permeable antirust agent for concrete structures (composition 1 to 6) of this invention shown in Examples 1-6. The concentration of nitrite ions in the portion having a depth of 25 to 35 mm is such that when the compositions 7 to 13 as shown in Comparative Examples 1 to 7 are applied to the concrete surface, the portion having a depth of 25 to 35 mm is introduced into the concrete structure. The concentration of the infiltrated nitrite ion is about twice as large as that of the inside of the concrete structure. Therefore, it can be seen from this result that the diffusibility of the permeable rust preventive of the present invention into the concrete is dramatically improved as compared with Comparative Examples 1 to 7.

  Moreover, although the density | concentration of a nitrite ion is high in Examples 4-6 compared with Examples 1-3, the penetration diffusibility which is inferior is obtained, The permeability rust prevention for concrete structures of this invention In the case of the agent, it can be seen that a high concentration of the surfactant can be added to the high concentration of nitrite.

  Furthermore, as shown in the results of Examples 1, 3, and 4 in Table 8 and the results of Comparative Examples 5 and 7, the permeable rust preventive of the present invention is a combination of a conventional nonionic surfactant and an anionic surfactant. Compared with the permeable rust preventive agent (composition 11) and the permeable rust preventive agent (composition 13) compounded with a nonionic surfactant, the foaming property is extremely small and the wettability is excellent. It is confirmed that it is preferable in terms of coating workability. Further, from the results of Table 8, it is confirmed that 2,4,7,9-tetramethyl-5-decyne-4,7-diol is excellent in the effect of improving the antifoaming property of the liquid.

Example 7
This test structure was constructed using an RC concrete structure (approx. 25 mm of actual cover thickness was about 25 mm) with a concrete-exposed finished outer wall surface that was about 25 years old. Composition 3 was applied to the product, and the diffusivity of nitrite ions into the existing concrete structure was measured. The application method is as follows.

The concrete outer wall surface (longitudinal surface) of the test structure was washed with high-pressure water, and the surface to be cleaned was used as a surface for application of the composition 3. After the concrete wall surface was dried, the composition 3 as a permeable rust preventive for concrete structures of the present invention was applied four times with a roller at a coating amount of 200 ml / m ² for a total of 800 ml / m ² . In addition, the moisture content in the concrete after washing | cleaning and drying of a test structure was 4-6 mass%. A ket concrete mortar moisture meter HI-520 (manufactured by Kett Science Laboratory Co., Ltd.) was used for measuring the moisture content.

  Six months after application, the core (50 mm diameter x 80 mm depth cylinder) specimen is cut from the concrete outer wall of the test structure to a position with a depth of 80 mm in the thickness direction of the test structure. The nitrite ions collected from the collected portion (cylindrical specimen) are identified in the range shown in the column “Deep penetration from wall surface” in Table 9 in the depth direction from the outer wall surface of the concrete. A portion of the test body was cut out to form a test piece, and the penetration amount of nitrite ions (content of nitrite ions at each penetration depth from the wall surface) was measured for each test piece. The results are shown in Table 9. At this time, the penetration depth and penetration amount of nitrite ions were measured by calculating the nitrite ion content by the “analysis method of nitrite ions” similar to the method described in Example 1.

  Furthermore, using a test piece of a portion having a depth of 25 to 35 mm from the concrete outer wall surface for the cylindrical test body, the chloride contained in the filtrate extracted by water in the same manner as described in Example 1 and obtained by filtration. The content rate of product ions was measured. The chloride ion content was measured by an ion chromatographic method in the same manner as the nitrite ion content was measured. Thereby, the content rate of the soluble chloride ion in a concrete structure is measured. As a result of the measurement, the content of soluble chloride ions was 2000 ppm.

  Moreover, the neutralization depth was measured about the cylindrical test body. Neutralization depth is determined by dividing the collected cylindrical specimen into two parts (longitudinal division) and spraying a phenolphthalein 1% solution onto a concrete section (phenolphthalein method). This was carried out by measuring the area where no discoloration occurred. The neutralization depth was an average of 25 mm.

Comparative Example 8
The result of measuring the diffusivity of nitrite ions into the existing concrete structure in the same manner as in Example 7 except that the composition 11 was used instead of the composition 3 used in Example 7 was Table 9 shows.

(Table 9)

  As shown in Table 9, the nitrite ion content in the “penetration depth of 25 to 35 mm from the wall surface” around the reinforcing bar portion at a depth of 30 mm inside the outer wall concrete is the case of Example 7 and Comparative Example 8 Compared with the case of, it is about 2.5 times. Therefore, it can be seen that the permeable rust preventive for concrete structures of the present invention is superior in osmotic diffusivity as compared with Comparative Example 8. For this, since the permeable rust preventive agent of the present invention has a reduced dynamic surface tension compared to the conventional permeable rust preventive agent such as the composition 11 used in Comparative Example 8, It is considered that the wettability of the permeable rust preventive agent to the concrete wall surface is also contributing.

  According to Example 7, the content of soluble chloride ions in the pore aqueous solution in the concrete was 2000 ppm in a portion having a depth of 25 to 35 mm around the reinforcing bar portion at a depth of 30 mm from the concrete wall surface. . Here, in the concrete structure, the nitrite ion content necessary to suppress the progress of corrosion due to rust of the reinforcing bars is nitrite ion / chloride ion = 0.6 (molar ratio) on the experimental rule. Yes. Then, considering that the molar ratio 0.6 is 0.78 in terms of mass ratio, the nitrite ion content necessary to suppress corrosion due to rust of the reinforcing bars is about 1600 ppm. Therefore, in the case of the rust preventive agent for concrete according to the present invention, it can be confirmed that a necessary and sufficient amount of nitrite ions has reached the rebar placement site.

  The permeable anticorrosive agent for concrete structures of the present invention is applied to the concrete wall surface of the existing concrete structure, and the nitrite ions in the antirust agent are sufficiently infiltrated to the position of the reinforcing steel inside the concrete. It is possible to improve the durability of the concrete structure by suppressing the progress of the aging due to the rust of the steel material.

Claims (6)

Penetration prevention for concrete structures characterized by comprising 2,4,7,9-tetramethyl-5-decyne-4,7-diol, ether type nonionic surfactant, nitrite and water Rust agent.
2,4,7,9-tetramethyl-5-decyne-4,7-diol and an ether type nonionic surfactant are blended in an aqueous nitrite solution in which nitrite is dissolved in water. The permeable rust preventive for concrete structures according to claim 1.
2,4,7,9-Tetramethyl-5-decyne-4,7-diol is 0.005 to 2% by mass, ether type nonionic surfactant is 0.05 to 5% by mass, and nitrite is 1 to 40%. The permeable rust preventive agent for concrete structures according to claim 1 or 2, characterized in that it is contained by mass%.
The permeable rust preventive for concrete structures according to any one of claims 1 to 3, wherein the ether type nonionic surfactant is a secondary higher alcohol ethoxylate.
The permeable rust preventive for concrete structures according to any one of claims 1 to 4, wherein the nitrite is calcium nitrite or lithium nitrite, and the pH is 9 or more.
  A silicate aqueous solution is applied to the surface of the concrete structure after applying the permeable rust inhibitor for a concrete structure according to any one of claims 1 to 5 to the surface of the concrete structure in which steel is embedded. The method of rust-proofing the steel material inside a concrete structure, characterized by applying