JP5828786B2 - Dense layer forming agent for concrete - Google Patents

Description

  The present invention relates to a dense layer forming agent for concrete containing a fatty acid ester mixture, and in particular, drying shrinkage of a hardened cement body by modifying the surface state of the hardened cement body and preventing moisture intrusion and dissipation. It is related with the dense layer forming agent for concrete which can improve durability of a hardening body and can prevent deterioration over a long term.

  Hardened concrete is a hydraulic composition consisting of a reaction between water and cement. During the hardening process, chemical loss of water occurs due to hydration in the hardened body, while the surface layer undergoes drying due to the exposure environment, Physical loss occurs. In general, strength is increased over a long period of time by retaining moisture in the cured body by appropriate curing, etc., but water dissipation to the outside of the cured body hinders the development of strength of the cemented body, and further, initial cracking occurs. It can also be the main factor. Also, the hardened cement that has been dried for a long time may cause distortion of the member due to shrinkage, eventually promoting the occurrence of cracks on the member surface, deterioration of the concrete structure due to water leakage, etc., which may lead to structural defects. is there. Examples of the deterioration phenomenon of the hardened cement body other than deterioration due to drying include alkali aggregate reaction and salt damage. These deterioration phenomena are promoted by moisture intrusion into the hardened body. From such a viewpoint, in order to prevent the deterioration of the concrete structure, it is required that the hardened body exhibit both the effects of drying suppression and moisture intrusion prevention (water absorption prevention) satisfactorily for a short period and a long period.

As a measure for preventing the deterioration phenomenon, for example, Patent Document 1 proposes a water repellent composition using a fatty acid ester. In Patent Document 2, an emulsion of a saturated fatty acid ester is applied as a drying inhibitor.
In addition, as a durability improver composed of a silane compound, for example, Patent Document 3 proposes a molded body in which an alkylpolysiloxane having water repellency is internally added, and Patent Document 4 further includes an alkylalkoxysilane. There has been proposed a method of impregnating a concrete surface to impart water repellency. Further, as a surface impregnating agent for reducing drying shrinkage and preventing moisture from entering, Patent Document 5 proposes a mixture of an organoalkoxysilane and a glycol ether surfactant. Patent Document 6 proposes a polyalkylene oxide derivative of tetraalkoxysilane as an agent for improving the drying shrinkage reduction property.

Japanese Patent Laid-Open No. 7-69696 JP 2008-273765 A JP 58-2252 A Japanese Patent Laid-Open No. 2-16186 Japanese Patent Laid-Open No. 3-93680 International Publication No. 04/108628 Pamphlet

The concrete durability improvers using fatty acid ester compounds that have been proposed so far are mainly aimed at increasing the compressive strength and imparting water repellency by suppressing the drying of the cured product, as shown in the above-mentioned literature. Was. However, although these technologies are excellent in the ability to prevent deterioration in a short period of time after placement, there is still room for improvement in securing long-term durability over 28 days of age, such as a decrease in waterproofing effect over time. there were. In addition to the long life of civil engineering structures in recent years, there is also a great demand for shrinkage reduction as a means of preventing cracks in concrete.
In addition, in terms of enhancing the functionality of the paint-type curing agent applied to the surface of the cured body, conventionally, only the surface modification of the coating film has been focused, and the cured body itself is impregnated from the surface layer of the concrete. There is still room for improvement in the technology for modifying physical properties.
As described above, the conventionally proposed durability improvers, water repellents, drying shrinkage reducing agents, etc. are individually used for the causes of deterioration phenomena such as short-term drying suppression and imparting water repellency to the cured body surface. There is no proposal for a hardened concrete for concrete that has been devised to improve both dryness suppression and moisture intrusion prevention (water absorption prevention) over the short and long term of the hardened body.
The present invention fully develops the strength of the hardened concrete due to the curing effect, and also has resistance to surface cracks by improving water absorption prevention and shrinkage reduction properties, and also suppresses the intrusion of carbon dioxide and chloride ions Then, it is providing the dense layer forming agent for concrete as a new chemical | medical agent for concrete hardening bodies which can reduce concrete deterioration by these.

  As a result of studying the above problems and conducting research, the present inventors applied a fatty acid ester mixture having a specific configuration to a hardened cement body to suppress concrete shrinkage at the time of hardening and after hardening. It has been found that the reduction of drying shrinkage and water absorption prevention that occur after use after curing can be maintained over a long period of time.

That is, this invention relates to the dense layer forming agent for concrete containing the fatty acid ester mixture (A) represented by following General formula (1).
R ² CO—O—R ³ (1)
(In the formula, R ¹ CO represents a fatty acid residue having 12 to 24 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms. The R ¹ CO is a long group of all fatty acid residues. Fatty acid residues in which the proportion of chain monounsaturated fatty acid residues is 20 to 90% by mass and the proportion of long-chain diunsaturated fatty acid residues is 5 to 80% by mass.)
A preferred embodiment of the present invention is the above general formula (1) (wherein R ¹ CO represents a fatty acid residue having 12 to 24 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms.) R ¹ CO has a long chain saturated fatty acid residue ratio of 3 to 40% by mass, a long chain monounsaturated fatty acid residue ratio of 20 to 50% by mass, and a long chain diunsaturated fatty acid. A fatty acid ester mixture (A) represented by a fatty acid residue in which the proportion of residues is 10 to 40% by mass and the proportion of long-chain triunsaturated fatty acid residues is 0 to 10% by mass). The present invention relates to a dense layer forming agent for concrete.

In the fatty acid ester mixture (A) represented by the general formula (1), R ¹ CO has a long-chain monounsaturation ratio of 0-40% by mass of long-chain saturated fatty acid residues in the total fatty acid residues. The proportion of fatty acid residues is 20 to 90 mass%, the proportion of long-chain diunsaturated fatty acid residues is 5 to 80 mass%, and the proportion of long-chain triunsaturated fatty acid residues is 0 to 15 mass%. preferable.
Moreover, in the fatty acid ester mixture (A) represented by the general formula (1), R ¹ CO has a proportion of long-chain saturated fatty acid residues having 16 to 24 carbon atoms in the total fatty acid residues of 3 to 40 masses. %, The proportion of long-chain monounsaturated fatty acid residues having 16 to 24 carbon atoms is 20 to 50% by mass, the proportion of long-chain diunsaturated fatty acid residues having 16 to 24 carbon atoms is 10 to 40% by mass, And it is preferable that the ratio of a C16-24 long-chain triunsaturated fatty acid residue is 0-10 mass%.
Furthermore, in the fatty acid ester mixture (A) represented by the general formula (1), R ² CO has a proportion of long-chain monounsaturated fatty acid residues having 16 to 24 carbon atoms in the total fatty acid residues of 30. More preferably, the proportion of long-chain diunsaturated fatty acid residues having 16 to 24 carbon atoms is 20 to 40 mass%.
In particular, in the fatty acid ester mixture (A) represented by the general formula (1), R ² CO has a proportion of long-chain saturated fatty acid residues having 18 carbon atoms in the total fatty acid residues of 10% by mass or less. The proportion of long-chain monounsaturated fatty acid residues having 18 carbon atoms is preferably 30 to 50% by mass, and the proportion of long-chain diunsaturated fatty acid residues having 18 carbon atoms is preferably 20 to 40% by mass. .

  In the present invention, the fatty acid ester mixture (A) represented by the general formula (1) preferably has an iodine value of 40 to 200.

Furthermore, in addition to the fatty acid ester mixture represented by the above formula (1), the present invention reacts an alkoxysilane, a hydrolyzate thereof or a polycondensate thereof with a polyoxyalkylene compound represented by the following general formula (2). It is related with the dense layer forming agent for concrete containing the alkoxysilane derivative (B) obtained by making it.
R ³ O— (AO) _n —H (2)
(In the formula, R ³ represents a hydrocarbon group having 1 to 18 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 20).
The alkoxysilane derivative (B) comprises an alkoxysilane, a hydrolyzate thereof or a polycondensate thereof as an alkoxypolyoxyalkylene group (of which the total number of added oxyalkylene groups is 2 to 6 is 90% by mass or more. The alkoxysilane derivative (B) modified with

  And this invention is the said dense layer forming agent for concrete, and a high performance AE water reducing agent, a high performance water reducing agent, an AE water reducing agent, a water reducing agent, an AE agent, a foaming agent, a defoaming agent, a curing agent, a water repellent. It also relates to a cement admixture, characterized in that it contains at least one other concrete additive selected from the group consisting of setting accelerators and setting retarders.

The dense layer forming agent for concrete according to the present invention is not limited to the limited performance improvement such as short-term drying suppression improved by the conventionally proposed durability improver, etc. And a new agent for hardened concrete that satisfactorily improves both the prevention of water intrusion (prevention of water absorption). By applying this dense layer forming agent to hardened cement, etc., the hardened cement can be dried at the initial stage of application. It is possible to prevent the occurrence of strength and promote the development of strength, reduce shrinkage, and maintain waterproofness while preventing the hardened cement body from drying over a long period of time. And the dense layer forming agent for concrete of this invention can also suppress the penetration | invasion of the carbon dioxide gas and chloride ion from a hardening body surface, and can contribute to the concrete deterioration prevention by these penetration | invasion.
In addition, the dense layer forming agent for concrete of the present invention is excellent in drying prevention and waterproof uniformity without causing a difference in performance even when applied to a large area such as a concrete exterior. be able to.

FIG. 1 is a view showing a front view (FIG. 1 (A)) of a test plate used in a water absorption waterproof performance test and a side view (FIG. 1 (B)) in which a glass instrument is installed. FIG. 2 is a front view (FIG. 2 (A)), a side view (FIG. 2 (B)), and a perspective view (FIG. 2 (FIG. 2 (B))) of a test plate installation frame for leaving the test plate used in the water absorption waterproof performance test outdoors. C)).

  Hereinafter, the present invention will be described in more detail. As will be described later, the dense layer forming agent for concrete of the present invention refers to a chemical agent that plays a role of maintaining a proper state of moisture (humidity) in the concrete surface layer by forming a dense layer on the concrete surface layer.

[(A) Fatty acid ester mixture represented by general formula (1)]
The (A) fatty acid ester used in the dense layer forming agent for concrete of the present invention (hereinafter also simply referred to as a dense layer forming agent) is a fatty acid ester represented by the following general formula (1).
R ¹ CO—O—R ² (1)
(In the formula, R ¹ CO represents a fatty acid residue having 12 to 24 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms. The R ¹ CO is a long group of all fatty acid residues. Fatty acid residues in which the proportion of chain monounsaturated fatty acid residues is 20 to 90% by mass and the proportion of long-chain diunsaturated fatty acid residues is 5 to 80% by mass.)
The R ¹ CO preferably has a long chain saturated fatty acid residue ratio of 0 to 0 in the total fatty acid residues.
40% by mass, the proportion of long-chain monounsaturated fatty acid residues is 20 to 90% by mass, the proportion of long-chain diunsaturated fatty acid residues is 5 to 80% by mass, and the proportion of long-chain triunsaturated fatty acid residues is 0-15% by mass
It is.

In the above R ¹ CO, long chain saturated fatty acid residues having 12 to 24 carbon atoms include lauric acid, myristic acid, pentasilic acid, palmitic acid, margaric acid, octadecanoic acid, nonadecanoic acid, arachidic acid, behenic acid and lignoserine. Examples include fatty acid residues derived from acids and the like.
Examples of long-chain monounsaturated fatty acid residues having 12 to 24 carbon atoms include fatty acid residues derived from myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, etc. Groups.
Examples of the long-chain diunsaturated fatty acid residue having 12 to 24 carbon atoms include fatty acid residues derived from linoleic acid, eicosadienoic acid, docosadienoic acid, and the like.
Examples of the long-chain triunsaturated fatty acid residue having 12 to 24 carbon atoms include fatty acid residues derived from linolenic acid, pinolenic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, and the like. Can be mentioned.

R ¹ CO is more preferably a long-chain saturated fatty acid residue having 16 to 24 carbon atoms and a long-chain mono-, long-chain di- or long-chain triunsaturated fatty acid residue having 16 to 24 carbon atoms, The ratio of the long-chain saturated fatty acid residue: the long-chain monounsaturated fatty acid residue: the long-chain diunsaturated fatty acid residue: the long-chain triunsaturated fatty acid residue is 3 to 40% by mass: 20 to 50%. It is preferable that it is the mass%: 10-40 mass%: 0-10 mass%.
More preferably, R ¹ CO preferably has a ratio of the long-chain monounsaturated fatty acid residue: the long-chain diunsaturated fatty acid residue of 30 to 50% by mass: 20 to 40% by mass. The ratio of the chain saturated fatty acid residue: the long-chain monounsaturated fatty acid residue: the long-chain diunsaturated fatty acid residue: the long-chain triunsaturated fatty acid residue is 5-30% by mass: 30-50% by mass. : 20-40% by mass: 0-10% by mass, for example, 5-20% by mass: 35-50% by mass: 25-40% by mass: 0-10% by mass, or 5-15% by mass: 40-50 % By mass: 30 to 40% by mass: 0 to 10% by mass.
In the fatty acid ester mixture (A) represented by the general formula (1), R ² CO has 10% by mass or less of long-chain saturated fatty acid residues having 18 carbon atoms in the total fatty acid residues, carbon atoms Most preferably, the number 18 of long-chain monounsaturated fatty acid residues is 30 to 50% by mass, and the number of carbon 18 long-chain diunsaturated fatty acid residues is 20 to 40% by mass.

In the above R ² , the alkyl group having 1 to 8 carbon atoms includes a methyl group, an ethyl group, n
A linear alkyl group which is a -propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-nonyl group or n-octyl group; isopropyl group, isobutyl group, sec-butyl group, tert-butyl group , Branched chain alkyl groups such as neopentyl group, 1-ethylpropyl group and 2-ethylhexyl group.
Among them, methyl group, n-butyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, n-octyl group and 2-ethylhexyl group are preferable, and isobutyl group, sec-butyl group and tert-butyl group are preferable. Most preferred.

  The fatty acid ester mixture (A) represented by the general formula (1) preferably has an iodine value of 40 to 200, particularly 40 to 180, more preferably 80 to 120.

[(B) alkoxysilane derivative]
In addition to the (A) fatty acid ester mixture, the dense layer forming agent for concrete according to the present invention may contain (B) an alkoxysilane derivative. The (B) alkoxysilane derivative is obtained by reacting an alkoxysilane, a hydrolyzate thereof or a polycondensate thereof with a polyoxyalkylene compound represented by the following general formula (2).
R ³ O— (AO) _n —H (2)
(In the formula, R ³ represents a hydrocarbon group having 1 to 18 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 20).

  Examples of the alkoxysilane include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and tetrabutoxysilane; methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyl Tributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptop Trialkoxysilanes such as pyrtriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane; dimethyldimethoxysilane, dimethyldiethoxy Dialkoxysilanes such as silane, diethyldimethoxysilane, and diethyldiethoxysilane can be used. Of these, the use of tetramethoxysilane and tetraethoxysilane is particularly preferred in the present invention from the viewpoints of availability, handling, and the like.

  The alkoxysilane hydrolyzate / polycondensate is prepared, for example, by dissolving a predetermined amount of alkoxysilane in water, water such as methanol, ethanol, ethyl acetate or an organic solvent, and heating or adding a predetermined amount of acid or base. And can be prepared by partial hydrolysis. Usually, the degree of polymerization is preferably 2 to 10.

In the polyoxyalkylene compound represented by the general formula (2), R ³ represents a hydrocarbon group having 1 to 18 carbon atoms, and the hydrocarbon group is an alkyl group having 1 to 30 carbon atoms; An aromatic group having 6 to 18 carbon atoms having a benzene ring such as a group, an alkylphenyl group, a phenyl group substituted with an alkylphenyl group, and a naphthyl group; and 2 to 18 carbon atoms such as an oleyl group and a linoleyl group Among them, an alkenyl group is preferably an alkyl group having 1 to 30 carbon atoms.
Specific examples of the alkyl group having 1 to 30 carbon atoms include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, and n-decyl group. Group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group and other linear alkyl groups; isopropyl group, sec-butyl group, tert-butyl group, neopentyl group, 1-ethylpropyl group, Examples thereof include branched alkyl groups such as 1-heptyldecyl group and 2-ethylhexyl group. Among these, an alkyl group having 1 to 8 carbon atoms is preferable, an n-butyl group and a 2-ethylhexyl group are more preferable, and an n-butyl group is most preferable.

In the polyoxyalkylene compound represented by the general formula (2), AO represents an oxyalkylene group having 2 to 4 carbon atoms, and specific examples include an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group. n is the number of added moles of alkylene oxide, and represents an integer of 0 to 20. When n is 2 or more, the oxyalkylene groups may be the same or different. (AO) When _n is composed of two or more types of alkyleneoxy groups, either block addition or random addition may be used, but block addition is preferred, and the terminal connected to the hydrogen atom is particularly ethylene. More preferred is an oxy group.

Specific examples of the polyoxyalkylene compound represented by the general formula (2) include polyethylene glycol polypropylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol polypropylene glycol monoethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol polypropylene glycol. Examples thereof include polyoxyalkylene alkyl ethers such as monopropyl ether, polyethylene glycol monopropyl ether, polyethylene glycol polypropylene glycol monobutyl ether, and polyethylene glycol monobutyl ether.

In the (B) alkoxysilane derivative, the compound obtained by reacting the polyoxyalkylene compound represented by the general formula (2) with the alkoxysilane or a hydrolyzate thereof is, for example, the following formula (3): It is represented by
R ⁴ _m -Si- (OR ⁵ ) _4-m (3)
In the above formula (3),
m represents a number from 0 to 3,
R ⁴ is independently when m represents 1 or when m represents 2 or 3,
Represents an alkyl group having 1 to 4 carbon atoms, a vinyl group, a 3-glycidoxypropyl group, a 3-mercaptopropyl group, a phenyl group or a 3,4-epoxycyclohexylethyl group;
R ⁵ represents a — (AO) n —OR ³ group when m represents ^3, and each independently represents an alkyl group having 1 to 4 carbon atoms or — (AO) represents an n-OR ³ group, provided that at least one of R ⁵ is - represents (AO) n-OR ³ group,
R ³ , AO and n have the same meaning as defined in the above formula (2).

Moreover, in the (B) alkoxysilane derivative, the compound obtained by reacting the polyoxyalkylene compound represented by the general formula (2) with the polycondensate of the alkoxysilane is, for example, the following formula (4) ).
^{(R 6) (R 7)} (R 8) Si- [O-Si (R 9) (R 10)] p-R 11 (4)
In the above formula (4),
R ^{6 to} R ¹¹ are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a vinyl group, a 3-glycidoxypropyl group, a 3-mercaptopropyl group, phenyl group, 3,4-epoxycyclohexyl ethyl group, - (AO) represents an n-OR ³ group, provided that at least one of R ⁶ to R ¹⁰ is - represents (AO) n-OR ³ group, p is Represents a natural number,
R ³ , AO and n have the same meaning as defined in the above formula (2).

In addition, among the whole polyoxyalkylene compounds represented by the general formula (2), the ratio of those in which n is 1 or less and the ratio in which n is 10 or more are each 5% by mass based on the mass of the whole compound. In the following, it is preferable to use those each having 4% by mass or less, particularly preferably 3% by mass or less. When the above alkoxysilane derivative is used as one component of the dense layer forming agent for concrete, if the ratio of n is 1 or less, the compound has high hydrophobicity and the water retention performance is reduced, resulting in a dry mass. Decrease rate will be high. On the other hand, if the ratio of n is 10 or more, the ratio of the polyoxyalkylene group in the compound increases, so that the hydrophilicity increases, and as a result, the water absorption preventing property decreases.
In particular, in terms of shrinkage reduction effect and waterproofness, the ratio of n to 2 to 6 is preferably 90% by mass or more, and the ratio of n to 2 to 4 is more preferably 90% by mass or more. Most preferably, the ratio of n = 3 is 90% by mass or more.

When trying to obtain a polyoxyalkylene alkyl ether having an addition mole number of alkylene oxide of about 2 to 6 using an alkali catalyst, the addition mole number usually has a distribution, so that the addition mole number is less than 1 To generate. Therefore, some reduction processing is required in that case, but conventionally known methods can be used to reduce the ratio. For example, by distilling an unpurified reaction liquid after the production of polyoxyalkylene alkyl ether, the content ratio thereof can be reduced. Moreover, by adding alkylene oxide to the monohydric alcohol having 1 to 18 carbon atoms in the presence of an acid catalyst, a composite metal oxide or the like, it can also be obtained directly without undergoing a fractionation operation such as distillation.

  The alkoxysilane derivative is prepared, for example, by charging the alkoxysilane, its hydrolyzate or its polycondensate, and the polyoxyalkylene compound represented by the above general formula (2) into a reaction vessel, and heating it to stop the alcohol produced. It can be obtained by conducting a transesterification reaction while leaving. The reaction temperature is usually about 50 to 150 ° C. In the transesterification reaction, a conventionally known catalyst can be used for promoting the reaction. The reaction ratio of the alkoxysilane, its hydrolyzate or its polycondensate and the polyoxyalkylene compound represented by the above general formula (2) is the same as that of the alkoxysilane, its hydrolyzate or its polycondensate. The polyoxyalkylene compound represented by the general formula (2) is preferably 0.3 to 1 equivalent, more preferably 0.5 to 1 equivalent per 1 equivalent of the group.

[Dense layer forming agent for concrete]
In the dense layer forming agent for concrete of the present invention, when using (B) an alkoxysilane derivative in addition to the (A) fatty acid ester mixture, the blending ratio of the (A) fatty acid ester mixture and (B) the alkoxysilane derivative is: It can be used within a range of 5 to 95:95 to 5 by mass ratio, more preferably 20 to 95:80 to 5, 50 to 95:50 to 5, 70 to 95:30 to 5, most preferably 70 to 90. : 30 to 10 can be used.

  In the dense layer forming agent for concrete according to the present invention, other components that may be included in addition to the (A) fatty acid ester mixture and (B) alkoxysilane derivative include a waterproofing agent, a water-proofing agent, A liquid medicine, an antifoamer, a curing agent, and a shrinkage reducing agent are mentioned. For example, hydrophobic compounds such as silicones, polysiloxanes, fatty oils, fatty acids and / or alkyl esters thereof, emulsions represented by paraffin wax emulsions, polyoxyalkylene monoalkyl ethers, specifically having 1 to 18 carbon atoms A polyoxyalkylene monoalkyl ether having 1 to 50 moles of an average addition mole number of an alkylene oxide having 2 to 4 carbon atoms; an alkylene group or alkenyl group having 1 to 8 carbon atoms A polyoxyalkylene glycol having an average addition mole number of 1 to 50 moles of alkylene oxide having 2 to 4 carbon atoms; or having an alkyl group or alkenyl group having 1 to 8 carbon atoms and having a carbon atom Number 2 to 4 alkyleneoxy Polyoxyalkylene alkyl ethers average addition mole number of 1 to 50 moles of, polybutene, etc. hydrocarbon polymer compounds typified polyisobutylene, and the like. The compounding ratio of these other components used in combination is the mass ratio of the (A) fatty acid ester mixture or the total mass of the (A) fatty acid ester mixture and (B) alkoxysilane derivative: the total of other components used in combination. Mass = 50: 50 to 99: 1, preferably 70:30 to 99: 1.

As will be described later, the dense layer forming agent for concrete according to the present invention exerts its effect mainly by applying or impregnating the surface of the cement composition after curing, but it can also be used by previously blending with cements. . Cement used is not particularly limited. For example, ordinary Portland cement, early strength Portland cement, super early strength Portland cement, sulfate resistant Portland cement, moderately hot Portland cement, low heat Portland cement, white Portland cement, superfast Hard Portland cement, expanded cement, acid phosphate cement, self-hardening cement, lime slag cement, blast furnace cement, high sulfate slag cement, fly ash cement, keens cement, pozzolanic cement, alumina cement, roman cement, white cement, Magnesia cement, Minamata cement, Calcium aluminate, Silica cement, Silica fume cement, Jet cement, Eco cement, Gypsum, or Taiheiyo cement as an example of commercial products Super super hard cement such as “Super Jet Cement (trade name)” manufactured by Sumitomo Osaka Cement Co., Ltd., and latent hydraulic materials such as hemihydrate gypsum and blast furnace slag, etc. Can be mentioned. These cements can be used alone or in combination of two or more selected from them. Moreover, the dense layer forming agent for concrete of this invention can be used for the concrete (concrete product, ready-mixed concrete, lightweight concrete) and mortar which mix | blended sand, pebble, lime, etc. with these cements.

  The use mode of the concrete dense layer forming agent for concrete of the present invention is not particularly limited, and is used in the same manner as a conventionally known concrete modifier, for example, applied (or sprayed / sprayed) to the surface of a hardened or semi-cured cement. -The aspect which impregnates by spraying etc. is mentioned. In addition to being applied to the surface of the cured product, the dense layer forming agent is used by adding to cement kneading water, adding the cement while kneading it, oil absorbing powder such as silica It is also possible to adopt a mode in which it is absorbed into a solid and added to cement.

When apply | coating the dense layer forming agent for concrete of this invention with respect to a cement hardening body, about 50-300 g / m < ² > is normally used with respect to the surface. Moreover, when mix | blending with cement beforehand and using it, 0.1-10 mass% is preferable with respect to cement mass. However, the amount of addition of the dense layer forming agent for concrete of the present invention is not limited to this because it varies depending on the concrete material and blending conditions.

  The concrete dense layer forming agent of the present invention can be mixed with other cement additives and used in the form of a so-called cement admixture. Other cement additives that can be formulated include curing agents, mold release agents, antifoaming agents, shrinkage reducing agents, surface aesthetics improvers, water repellents, setting accelerators, setting retarders, concrete coatings, surface repairs Materials and the like. In addition to these, various admixtures commonly used in cement compositions such as thickeners, expansion agents, rust inhibitors, organic fibers, inorganic fibers, organic polymers, and pigments can be used.

By applying the dense layer forming agent for concrete of the present invention to a hardened cement body or the like, it has a function as a so-called curing agent that suppresses drying of the hardened cement body and promotes the development of strength at the initial stage of application, and also contracts. The waterproof property can be maintained while suppressing the drying of the hardened cement body over a long period of time. That is, the dense layer forming agent of the present invention penetrates into the surface layer portion from the pores of the concrete surface, reaches the slight gaps of cement and aggregate constituting the hardened concrete body, closes the voids and closes the dense surface layer portion of the concrete. For new concrete hardened bodies that form a layer to prevent moisture from entering and exiting the surface of the concrete and adjust the moisture on the surface of the concrete to a moderate level of moisture without being too dry (dry) or excessive (water absorption) It is a drug.
As one of the reasons why the dense layer forming agent for concrete of the present invention is excellent in the moisture control effect of the concrete surface layer, the dense layer forming agent is used in the form of a fatty acid ester mixture by combining fatty acid esters having different numbers of unsaturated bonds. Can alleviate each intermolecular interaction when the fatty acid ester is arranged by penetrating into the hardened body surface layer, thereby making the fatty acid ester arrangement more dense and forming the dense layer described above It is guessed. And this can keep the moisture of the concrete surface appropriate, and as a result, it is assumed that it contributes to high curing effect and water absorption prevention, and also contributes to the suppression of intrusion of carbon dioxide and chloride ions. Is done.
Furthermore, the alkoxysilane derivative has a structure in which the balance between hydrophilicity and hydrophobicity is optimized, and has a structure suitable for penetrating into the surface layer portion from the cement hardened body surface to the inside of several centimeters. By further adding an alkoxysilane derivative, the derivative penetrates into the surface layer portion of the cured body, like the above-mentioned fatty acid ester, where the derivative is hydrolyzed to form a silicate, and water or water present in the voids inside the cured body. It reacts with calcium hydroxide to form a gel, which contributes to moisture retention and also contributes to the closing of voids and the formation of a dense layer in the concrete surface layer. Therefore, coupled with the prevention of moisture penetration from outside and the realization of a high curing effect of the fatty acid ester mixture described above, the realization of an environment with moderate moisture in the concrete surface layer, and the prevention of drying of the hardened cement body and the maintenance of waterproofness, Furthermore, it is presumed that this will lead to the expression of a synergistic effect in suppressing the invasion of carbon dioxide and chloride ions.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Fatty acid ester mixture]
Table 1 shows the composition of the fatty acid ester mixture represented by the formula (1) R ¹ CO—O—R ² used in the following Examples , Reference Examples and Comparative Examples.

[Alkoxysilane derivatives]
The alkoxysilane derivative used in the following examples was prepared by the following procedure. In the text, the molar ratio of the polyoxyalkylene compound (hereinafter also referred to as polyalkylene glycol) to the alkoxysilane is the charged molar ratio of the polyoxyalkylene compound to 1 mole of the alkoxy group in the alkoxysilane structure.

(Production Example 1: Production method of alkoxysilane derivative (compound B-1))
In a reaction vessel equipped with a stirrer, thermometer, condenser, distillate collection tank and nitrogen introduction tube, 401 parts of tetraethoxysilane, 1593 parts of polyethylene glycol monobutyl ether (average of polyethylene glycol repeating units is 3) A molar ratio to alkoxysilane: 4) and 5 parts of triethylamine were charged. The reactor was placed in a nitrogen stream, heated to 140 ° C. over 2 hours, stirred at the same temperature for 7 hours, and reacted while distilling the produced ethanol. The end point of the reaction was judged by the amount of ethanol recovered to obtain 1569 parts (yield 95%) of a pale yellow liquid (Compound B-1).

(Production Example 2: Production method of alkoxysilane derivative (compound B-2))
Charge amount, apparatus and production procedure of triethylamine are in accordance with Production Example 1, 317 parts of tetraethoxysilane, polyethylene glycol mono-2-ethylhexyl ether instead of polyethylene glycol monobutyl ether (the average of polyethylene glycol repeating units is 3) Using 1601 parts (molar ratio to alkoxysilane: 4), compound B-2 (1560 parts, yield 95%) was obtained.

(Production Example 3: Method for producing alkoxysilane derivative (compound B-3))
The amount of triethylamine charged, the apparatus and the production procedure were the same as in Production Example 1. Instead of tetraethoxysilane, 1087 parts of ethoxysilane polycondensate (average polymerization degree 5), polyethylene glycol monobutyl ether (average of polyethylene glycol repeating units was 3) Compound B-3 (1707 parts, 95% yield) was obtained using 908 parts (something) (molar ratio to alkoxysilane: 3).

It shows in Table 3 mentioned later using the said fatty-acid ester mixture: Mixtures A-1 to A-8, Comparative mixture C-1 and C-2, and the said alkoxysilane derivative: Compound B-1 to B-3 prepared above. It applied to the hardened | cured material of the fresh concrete manufactured in the following procedures as the dense layer formation agent of an Example , a reference example, and a comparative example, and various performances were evaluated. As Comparative Example 1, a cured body (blank) that did not use a dense layer forming agent was also evaluated.

[Manufacture of fresh concrete for testing]
The specifications of the concrete were nominal strength 30 MPa, slump: 8 ± 2.5 cm, air amount: 4.5 ± 1.5%. Table 2 shows the composition of the test concrete. The kneading method uses a horizontal biaxial forced kneading mixer with a nominal capacity of 1 m ³ , and the amount of concrete produced in each batch is set to 0. 0.
Make 8m ³ × 1 batch, first put cement and fine aggregate into mixer and knead for 10 seconds, then mix water, admixture and coarse aggregate, mix for 120 seconds, then discharge, Provided.

[Concrete test evaluation using dense layer forming agent]
<Compressive strength test of concrete>
A specimen (φ10 cm × 20 cm) for compressive strength test was prepared from the fresh concrete prepared by the above procedure, and a compressive strength test was performed. The specimen was demolded the day after production, and each dense layer forming agent shown in Table 3 was uniformly applied to the entire specimen surface (upper surface, bottom surface, side surface) (150 g / m ^2).
And air curing was performed in an environment of a temperature of 20 ° C. and a humidity of 60%. The compressive strength test was based on JIS A 1108 (Concrete compressive strength test method), and after applying the modifier, the compressive strength at a material age of 7 days and a material age of 28 days was measured. The results are shown in Table 3.

<Dry weight loss rate, length change rate>
A concrete specimen (10 cm long × 10 cm wide × 40 cm height) for measuring the dry mass reduction rate and the length change rate was produced from the fresh concrete produced by the above procedure, and the dry mass reduction rate was measured. . The specimen was unframed at the age of 3 days, and after applying each dense layer forming agent shown in Table 3 (150 g / m ² ) on the top surface of the concrete specimen prepared immediately after the deframement, the mass of the specimen was measured. This was used as the base point of the dry mass reduction rate. Moreover, the dimension of the specimen was measured by the mold gauge method, and this was used as the reference value for the rate of change in length. Thereafter, the specimen was stored under the conditions of a temperature of 20 ° C. and a humidity of 60%, and the dry mass reduction rate and length change rate at the age of 28 days were calculated using the formulas described below.
Here, the smaller the value of the dry mass reduction rate means that the moisture dissipation in the test sample can be suppressed. Moreover, the value of the length change rate means that the smaller the value of the length change rate of the specimen (Comparative Example 1) to which the dense layer forming agent is not applied, the more the drying shrinkage of the specimen is suppressed. . The results are shown in Table 3.

《Dry weight loss rate》
Dry mass reduction rate (%) = {[mass of specimen after test−mass of specimen before test] / [mass of specimen before test]} × 100
《Length change rate》
Length change rate (10 ⁻⁶ ) = [length of each specimen after test (mm) −length of specimen before test (mm)] / [length of specimen before test (mm)]

<Water absorption prevention performance test>
A test plate (length 1000 mm × width 1,000 mm × thickness 100 mm, see FIG. 1) was prepared from the fresh concrete prepared according to the above procedure, and applied to the measurement of water absorption prevention performance. Each dense layer forming agent shown in Table 3 was applied to the surface of the test plate (150 g / m ² ), and then the test plate was left outdoors using a test plate installation frame assembled with a single pipe (see FIG. 2).
At the age of 28 days, a funnel-shaped glass appliance 2 formed by combining two cylinders having different thicknesses at six locations on the surface of the test plate 1 was installed (adhered) using an adhesive 3 (FIG. 1). (See (B)). The diameter 2a of the thick cylindrical portion in contact with the test plate 1 of the glass instrument 2 is 27 mmφ, the length 2c of the thick cylindrical portion is 40 mm, the diameter 2b of the thin cylindrical portion is 12 mmφ, and the length 2d of the thin cylindrical portion is 115 mm. is there. FIG. 1 (A) shows the adhesion points (test points) of glassware: upper A point to C point and lower D to F points. The inside of the installed glassware 2 was filled with ion exchange water, and the opening 2-1 of the glassware 2 was covered and sealed with a paraffin film. For each of the test points A to F, the water absorption of the ion-exchanged water after 48 hours is measured, and each unit of the upper test point (A point to C point) and the lower test point (D point to E point) The average value of water absorption per unit area (1 cm ² ) (unit water absorption) was determined. The results are shown in Table 3.

  In addition, compared with the blank test plate (Comparative Example 1) to which the dense layer forming agent is not applied, the water absorption preventing performance is able to suppress moisture intrusion into the specimen as the unit water absorption value is smaller. Means that Furthermore, the unit water absorption values of the upper part and the lower part that are equal indicate that the predetermined performance is obtained uniformly.

<Permeation suppression performance test for carbon dioxide>
A test specimen (10 × 10 × 20 cm) is prepared from the fresh concrete prepared according to the above procedure in accordance with JIS A 1153 (accelerated neutralization test method for concrete), and the entire test specimen (top, bottom, side) is prepared. Uniformly apply each dense layer forming agent shown in Table 3 (150 g / m ² )
Each specimen was stored under conditions of a temperature of 20 ° C. and a humidity of 60%. After one week of material age, temperature curing 20 ° C, humidity 60%, CO ₂ concentration 5% accelerated curing, in accordance with JIS A 1152 (measurement of the carbonation depth of concrete), 28 days after the specimen The neutralization depth (carbon dioxide permeability) was measured.

<Chlorine ion penetration inhibition performance test>
A test specimen (10 × 10 × 40 cm) was prepared from the fresh concrete prepared according to the above procedure, and each dense layer forming agent shown in Table 3 was uniformly applied to the entire specimen surface (upper surface, bottom surface, side surface) (150 g / m ² ) and each specimen was stored under conditions of a temperature of 20 ° C. and a humidity of 60%. After one week of material age, each test specimen was sprayed with a 5% NaCl aqueous solution at 40 ° C. for 3 days and then dried at 60% humidity for 4 days.
In accordance with 1171 (Testing method for polymer cement mortar), the salt penetration depth after 28 days was measured.

As shown in Table 3, the hardened cement body (Example 3 to Example 7 and Example 9 to 9 ) to which the dense layer forming agent for concrete of the present invention containing a fatty acid ester mixture (A- 3 to A- 7 ) was applied. Example 11 ) is a blank cured product without using a dense layer forming agent (Comparative Example 1), a fatty acid ester mixture (C-1) and a long-chain di-unsaturated compound with a large proportion of long-chain monounsaturated fatty acid residues. Compared to cured bodies (Comparative Example 2 and Comparative Example 3) to which a dense layer forming agent containing a fatty acid ester mixture (C-2) containing a large proportion of saturated fatty acid residues is applied, the compression strength is high, and the dry mass reduction rate and As a result, the rate of change in length was low, and the value of unit water absorption indicating water absorption prevention was also small. In particular, in the cured bodies of Comparative Examples 2 and 3, although the difference between the upper and lower values of the unit water absorption amount is large, the cured bodies of Examples 3 to 7 and Examples 9 to 11 have unit water absorption. As a result, there is almost no difference in the value between the upper part and the lower part of the amount, and the cured body to which the dense layer forming agent for concrete of the present invention is applied can obtain a predetermined performance uniformly regardless of the place (location) applied As a result.
Further, by combining with alkoxysilane derivatives (B-1 to B-3) (Examples 9 to 11), strength, shrinkage reduction (dry mass reduction rate, rate of change in length) and water absorption prevention are further improved. The result that it was excellent was obtained.
Furthermore, the cured bodies (Example 3 to Example 7 and Examples 9 to 11 ) to which the dense layer forming agent for concrete of the present invention is applied are all carbon dioxide and chloride as compared with the cured bodies of the comparative examples. The result was obtained that the permeability (diffusibility) of ions was suppressed.
In addition, although Example 3 -Example 7 and Example 9-Example 11 have improved the compressive strength 9-10% compared with the comparative example 1, this is Example 3 -Example 7 and implementation. This indicates that the hardened cement bodies of Examples 9 to 11 have a dense structure inside the hardened body surface layer compared with the hardened cement body of Comparative Example 1, and thus carbon dioxide gas and chloride ions. It seems to have led to suppression of permeability (diffusivity).
As described above, by applying the dense layer forming agent for concrete containing the fatty acid ester mixture (A) of the present invention to a hardened cement body or the like, maintaining waterproofness while preventing drying of the hardened cement body over a long period of time, A higher shrinkage reduction effect than the conventional one can be exhibited.

DESCRIPTION OF SYMBOLS 1 ... Test plate 2 ... Glass instrument 2-1 ... Opening part 3 ... Adhesive

Claims (8)

A dense layer forming agent for concrete containing a fatty acid ester mixture (A) represented by the following general formula (1).
R ¹ CO—O—R ² (1)
(In the formula, R ¹ CO represents a fatty acid residue having 12 to 24 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms. The R ¹ CO is long in all fatty acid residues. The proportion of chain saturated fatty acid residues is 3 to 40% by mass, the proportion of long-chain monounsaturated fatty acid residues is 20 to 50% by mass, the proportion of long-chain diunsaturated fatty acid residues is 10 to 40% by mass, and long (The fatty acid residue whose ratio of a chain triunsaturated fatty acid residue is a ratio of 0-10 mass% is shown.) In the fatty acid ester mixture (A) represented by the general formula (1), R ¹ CO has a proportion of long-chain saturated fatty acid residues having 16 to 24 carbon atoms in the total fatty acid residues of 3 to 40 masses. %, The proportion of long-chain monounsaturated fatty acid residues having 16 to 24 carbon atoms is 20 to 50% by mass, the proportion of long-chain diunsaturated fatty acid residues having 16 to 24 carbon atoms is 10 to 40% by mass, And the dense layer forming agent for concrete of Claim 1 whose ratio of a C16-C24 long-chain triunsaturated fatty acid residue is a ratio of 0-10 mass%. In the fatty acid ester mixture (A) represented by the general formula (1), R ¹ CO has a ratio of long-chain monounsaturated fatty acid residues having 16 to 24 carbon atoms in the total fatty acid residues of 30 to 30%. The dense layer forming agent for concrete according to claim 2 , wherein the proportion of long-chain diunsaturated fatty acid residues having 16 to 24 carbon atoms is 50 to 40% by mass and 20 to 40% by mass. In the fatty acid ester mixture (A) represented by the general formula (1), R ¹ CO has a ratio of long-chain saturated fatty acid residues having 18 carbon atoms in the total fatty acid residues of 10% by mass or less, carbon the proportion of long chain monounsaturated fatty acid residues atoms 18 30 to 50 wt%, and the proportion of long Kusariji unsaturated fatty acid residues having 18 carbon atoms is 20 to 40 mass%, according to claim 2 Dense layer forming agent for concrete. The dense layer forming agent for concrete according to claim 1, wherein the fatty acid ester mixture (A) represented by the general formula (1) has an iodine value of 40 to 200. Furthermore, the alkoxysilane derivative (B) obtained by making alkoxysilane, its hydrolyzate, or its polycondensate react with the polyoxyalkylene compound represented by following General formula (2) is contained. The dense layer forming agent for concrete according to any one of claims 5 to 6.
R ³ O— (AO) _n —H (2)
(In the formula, R ³ represents a hydrocarbon group having 1 to 18 carbon atoms, AO represents an oxyalkylene group having 2 to 4 carbon atoms, and n represents an integer of 1 to 20). The alkoxysilane derivative (B) comprises an alkoxysilane, a hydrolyzate thereof or a polycondensate thereof as an alkoxypolyoxyalkylene group (of which the total number of added oxyalkylene groups is 2 to 6 is 90% by mass or more. The dense layer forming agent for concrete according to claim 6 , which is an alkoxysilane derivative (B) modified by The dense layer forming agent for concrete according to any one of claims 1 to 7 , and a high performance AE water reducing agent, a high performance water reducing agent, an AE water reducing agent, a water reducing agent, an AE agent, a foaming agent, A cement admixture comprising at least one other concrete additive selected from the group consisting of an antifoaming agent, a curing agent, a water repellent, a setting accelerator, and a setting retarder.

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