JP2022128958A - Resin to be blended with cement for building or civil engineering structure, and method of producing the same - Google Patents

Abstract

To provide a resin to be blended with cement, excellent in water absorption and syneresis even in the presence of an alkali in cement for a building or a civil engineering structure, thereby exhibiting excellent internal curing effect and capable of suppressing self-shrinkage of mortar and concrete.SOLUTION: The resin to be blended with cement for a building or a civil engineering structure, is composed of a crosslinked vinyl alcohol-based polymer, wherein a cumulative pore volume of pores having a pore diameter of 0.1 to 10 μm is 0.01 to 2.0 mL/g.SELECTED DRAWING: None

Description

The present invention relates to cement admixture resins for building or civil engineering structures and methods for producing the same.

In recent years, the aging of infrastructure such as highways and tunnels that were built during the high economic growth period has become an issue. One of the causes of deterioration of concrete products is acidification due to permeation of rainwater and air through cracked portions. Cracking of cement used in these building structures and civil engineering structures is said to be caused by the following capillary tension mechanism. 1) In the process of hydration of cement and water, the inside of the hardened body becomes dry and voids are generated. 2) When the voids in the hardened body become unsaturated and a gas-liquid interface occurs, a meniscus is formed by the surface tension of water. 3) Negative pressure is generated in the liquid water, causing elastic volume reduction in the cured body. One of the factors is the decrease in volume of cement, that is, the occurrence of "autogenous shrinkage."

In order to suppress autogenous shrinkage of concrete, it is desirable to increase the amount of water to cement. It is increasingly being used in reduced amounts. However, in concrete with a reduced amount of water, since the inside of the voids in particular tends to dry out, the autogenous shrinkage is remarkable, which is one of the factors that reduce the strength of the building.

Non-Patent Document 1 shows that cracks can be suppressed by adding a water absorbent resin to cement paste. According to this, it is said that the water retained by the water-absorbent resin is gradually released to reduce capillary tension and suppress autogenous shrinkage in response to the drying of the inside of the voids due to the consumption of water accompanying the hydration reaction. Furthermore, after hardening, the water-absorbing resin separates and shrinks, leaving voids of a size corresponding to the swollen water-absorbing resin, which has the effect of alleviating cracks caused by the increase in volume due to residual water freezing in concrete and mortar. have.

Patent Document 1 discloses that a water-absorbent resin containing polyacrylic acid gel as a main component can be used for construction or civil engineering structure cement, and Patent Document 3 discloses that a thermally crosslinked modified polyvinyl alcohol resin can be used for excavation cement. disclosed. However, although polyacrylic acid gel exhibits high water absorption in deionized water and tap water, it does not absorb ions in polyelectrolyte solutions containing large amounts of calcium ions and aluminum ions contained in cement. Insolubilization progresses due to cross-linking, and the water absorption capacity may be extremely reduced. In addition, the modified polyvinyl alcohol-based resin has a problem that the cross-linking is broken under alkali in cement, and the water absorbing property cannot be maintained until it hardens.

In order to solve such a problem, Patent Document 2 discloses that a cationic or amphoteric water absorbent resin can suppress a decrease in water absorption even when it contains a large amount of polyelectrolyte contained in the cement composition, and excavation It is disclosed that it can be suitably used as a cement admixture for muddy water.

Japanese Patent Laid-Open No. 56-069257 WO2017-099082 Japanese Patent Application Laid-Open No. 1-203251

Application of Superabsorbent Polymers (SAP) in Concrete Construction: State-of-the-Art Report Prepared by Technical Committee 225-SAP, 2012.

However, according to the studies of the present inventors, although the cationic or amphoteric water absorbent resin shown in Patent Document 2 can retain a large amount of water, at the beginning of the curing process, water and cement water Since a sufficient amount of water cannot be supplied to the gap between the sum product and sand, the pressure due to capillary tension cannot be relieved, and a sufficient crack-suppressing effect cannot be exhibited in some cases. The problem to be solved by the present invention is to solve the above problems. To provide a cement additive having an internal curing effect that can supply

As a result of intensive studies to solve the above problems, the present inventors have found that by having a specific cumulative pore volume, the resin expresses water separation from the resin to cement, and a resin having a specific crosslinked structure is used. found that it has a sufficient amount of water absorption even in the presence of alkali in cement for construction or civil engineering structures, and arrived at the present invention.

[1] A resin for admixture with cement for building or civil engineering structures comprising a crosslinked vinyl alcohol polymer, wherein the cumulative pore volume of pores having a pore diameter of 0.1 to 10 μm is 0.01 to 2.0 mL. /g of cement admixture resin.
[2] The cement admixture resin according to [1], wherein the crosslinked structure of the vinyl alcohol polymer crosslinked product is derived from a polyhydric aldehyde compound or a polyhydric epoxy compound.
[3] The crosslinked vinyl alcohol polymer contains one or more functional groups selected from the group consisting of carboxyl groups, ester groups, sulfonic acid groups, amino groups and salts thereof, [1] or [ 2].
[4] The vinyl alcohol-based polymer crosslinked product contains one or more carboxylic acid-based monomer structural units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and derivatives thereof. ] The cement admixture resin according to .
[5] The cement admixture resin according to any one of [1] to [4], wherein the carboxylic acid-based monomer unit content is 0.1 mol % to 50 mol %.
[6] Any one of [1] to [5], including a step of performing a saponification reaction with 1 part by mass or more and 30 parts by mass or less of the vinyl alcohol polymer before saponification with respect to 100 parts by mass of the solvent. A method for producing a resin for cement admixture.
[7] The method for producing a cement admixture resin according to any one of [1] to [4], which includes a step of cross-linking the vinyl alcohol polymer by a heterogeneous reaction.
[8] An instant cement comprising the cement admixture resin according to any one of [1] to [5] and cement.
[9] An instant mortar containing the cement admixture resin according to any one of [1] to [5], cement and sand.
[10] Instant concrete containing the resin for cement admixture according to any one of [1] to [5], cement, sand and stone.
[11] A cement paste containing the instant cement of [8] and water.
[12] A fresh mortar containing the instant mortar according to [9] and water.
[13] Fresh concrete containing the instant concrete according to [10] and water.
[14] A mortar containing the resin for cement admixture according to any one of [1] to [5].
[15] Concrete containing the resin for cement admixture according to any one of [1] to [5].

The resin for cement admixture of the present invention is excellent in water absorption and water separation even in the presence of alkali in building or civil engineering structure cement, so that it has a high internal curing effect, that is, it can suppress autogenous shrinkage of mortar and concrete. .

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

The cement admixture resin of the present invention has a cumulative pore volume of 0.01 to 2.0 mL/g for pores having a pore diameter of 0.1 to 10 μm. As a result of investigation by the present inventors, the cumulative pore volume is 0.01 mL / g or more, so that the surface area is large and water that easily separates can be held in the pores. It has been found to be suitable for use as a resin. In addition, when the cumulative pore volume exceeds 2.0 mL/g, problems such as the formation of coarse aggregates in which particles are fused to each other during water absorption and the tendency to crush due to impact during transportation, etc. occur. do. The cumulative pore volume is preferably 0.1 mL/g or more, more preferably 0.15 mL/g or more, still more preferably 0.2 mL/g or more, preferably 1.5 mL/g or less, more preferably It is 1.0 mL/g or less, more preferably 0.5 mL/g or less.

The cement admixture resin that satisfies the above range of cumulative pore volume is used to adjust the concentration of polyvinyl acetate when producing polyvinyl alcohol by saponification of polyvinyl acetate, and to add vinyl alcohol polymer and glycerin, ethylene glycol, etc. By adjusting the content of the auxiliary agent component in the method of mixing the agent component to prepare a dispersion and eluting the auxiliary agent component from the dispersion, adjusting the degree of dispersion of the auxiliary agent component by adding a dispersant, etc. can be controlled. For example, in the former method, the cumulative pore volume is increased by decreasing the concentration of polyvinyl acetate in a solvent such as methanol, and the cumulative pore volume is decreased by increasing the concentration. The cumulative pore volume can be measured, for example, by mercury porosimetry, and more specifically, it is a value measured according to the method described in the Examples.

The cement admixture resin of the present invention preferably passes through a sieve with a nominal opening of 1000 μm, more preferably through a sieve with a nominal opening of 700 μm, even more preferably through a sieve with a nominal opening of 500 μm, and particularly preferably through a sieve with a nominal opening of 700 μm. It has a particle size that passes through a sieve with a nominal opening of 300 μm, preferably does not pass through a sieve with a nominal opening of 10 μm, more preferably does not pass through a sieve with a nominal opening of 30 μm, and still more preferably passes through a sieve with a nominal opening of 50 μm. It has a particle size that does not pass through a sieve with a nominal opening of 70 μm, particularly preferably. In one preferred embodiment, the cement admixture resin has a particle size that passes through a 1000 μm nominal sieve and does not pass through a 10 μm nominal sieve. When the cement-admixture resin has such a particle size, after the mortar or concrete hardens, the cement-admixture resin will repel water and shrink, leaving voids of appropriate size to freeze and thaw the water contained in the mortar or concrete. It is possible to appropriately exhibit the effect of suppressing cracks caused by.

As used herein, the term "structural unit" means a repeating unit that constitutes a polymer. 2 units”.

The cement admixture resin of the present invention comprises a crosslinked vinyl alcohol polymer from the viewpoint of suppressing elution of the resin in cement for building or civil engineering structures. The form of the crosslinked structure is not particularly limited, and examples thereof include crosslinked structures by ether bonds, acetal bonds, ester bonds, carbon-carbon bonds, and the like. The presence or absence of a crosslinked structure in the vinyl alcohol polymer can be measured, for example, by the elution rate in hot water at 100° C. or dimethylsulfoxide. Specifically, the elution rate indicated by the ratio of the mass of the eluted sample to the mass of the sample (mass of eluted sample x 100/mass of sample) must be a certain value or less (e.g., 90% by mass or less). The presence of a crosslinked structure can be confirmed by

An example of the ether bond is an ether bond formed by dehydration condensation between hydroxyl groups of a vinyl alcohol polymer. Another example of the ether bond is an ether bond formed when a polyepoxy compound having a plurality of epoxy groups in one molecule is used in the production of a vinyl alcohol polymer. An example of the acetal bond is an acetal bond formed when a polyhydric aldehyde compound having a plurality of aldehyde groups in one molecule is used in the production of a vinyl alcohol polymer. An example of the ester bond is an acetal bond formed when a polyvalent carbonyl compound having a plurality of carboxyl groups or ester groups in one molecule is used in the production of a vinyl alcohol polymer. Another example of the ester bond is an ester bond formed by dehydration condensation between a carboxyl group and a hydroxyl group of a polyvinyl alcohol polymer, or transesterification between an ester group and a hydroxyl group. Examples of the carbon-carbon bond include a carbon-carbon bond formed by coupling between carbon radicals of the vinyl alcohol polymer, which is generated when the vinyl alcohol polymer is irradiated with an active energy ray. . One type of these crosslinked structures may be contained, or a plurality of types may be contained. Among them, a crosslinked structure with an acetal bond, an ester bond, or an ether bond is preferable from the viewpoint of ease of production, and a crosslinked structure with an acetal bond or an ether bond is more preferable from the viewpoint of the base resistance (elution rate) of the crosslinked structure in cement. .

The crosslinked structure of the crosslinked vinyl alcohol polymer is preferably derived from a polyhydric aldehyde compound or a polyhydric epoxy compound. Examples of polyaldehyde compounds include glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, 1,9-nonanedial, adipaldehyde, malealdehyde, tartaraldehyde, citraldehyde, phthalaldehyde, isophthalaldehyde, and terephthalaldehyde. Difunctional aldehydes can be mentioned. When a polyhydric aldehyde compound is used, a hydroxyl group of one of the different molecular chains of the vinyl alcohol polymer undergoes an acetalization reaction with one aldehyde group of the polyhydric aldehyde compound, and two vinyl alcohols Two acetal bonds can be introduced by an acetalization reaction between the hydroxyl group of the other of the system polymers and another aldehyde group of the polyhydric aldehyde compound. Preferred types of compounds are polyaldehyde compounds because of their wide selection of solvents, and among them, glyoxal, malonaldehyde, succinaldehyde, and glutaraldehyde are particularly preferred because they can uniformly distribute crosslinks in the resin. More preferred.

The amount of the cross-linking agent relative to the hydroxyl groups of the vinyl alcohol-based polymer, which is the raw material of the vinyl alcohol-based polymer cross-linked product, is preferably 0.001 mol% from the viewpoint of facilitating maintenance of water absorbency in construction or civil engineering structure cement. Above, more preferably 0.005 mol% or more, still more preferably 0.01 mol% or more, still more preferably 0.03 mol% or more, preferably 0.5 mol% or less, more preferably 0.4 mol % or less, more preferably 0.3 mol % or less.

The vinyl alcohol unit content of the vinyl alcohol polymer is preferably 20 mol% or more, more preferably 50 mol% or more, and still more preferably 60 mol% or more, based on the total structural units of the vinyl alcohol polymer. is preferably 98 mol % or less, more preferably 95 mol % or less, and still more preferably 90 mol % or less. The content of the vinyl alcohol unit can be measured by FTIR, solid-state ¹³ C-NMR, or the like, but can also be calculated from the amount of acetic anhydride consumed when reacted with a certain amount of acetic anhydride.

The viscosity average polymerization degree of the vinyl alcohol polymer is not particularly limited, but from the viewpoint of ease of production, it is preferably 20000 or less, more preferably 10000 or less, still more preferably 4000 or less, and particularly preferably 3000 or less. . On the other hand, from the viewpoint of mechanical properties and elution resistance in water of the vinyl alcohol polymer, the viscosity-average degree of polymerization is preferably 100 or more, more preferably 200 or more, and still more preferably 400 or more. The viscosity average degree of polymerization can be measured by a method based on JIS K 6726. When having an ether structure, an acetal structure or an ester structure as a crosslinked structure, the measurement of the viscosity average degree of polymerization can be performed after cutting the crosslinked structure. The cleavage is performed by a general method, for example, a nucleophilic substitution reaction with a strong acid such as hydrobromic acid or hydroiodic acid for an ether structure, a hydrolysis reaction with an acid for an acetal structure, and an acid or alkaline reaction for an ester structure. This operation does not affect the viscosity average degree of polymerization of the vinyl alcohol polymer.

The vinyl alcohol polymer may contain structural units other than vinyl alcohol units. Examples of the other structural units include structural units derived from monomers for introducing functional groups described later; structural units derived from vinyl carboxylates such as vinyl acetate and vinyl pivalate; ethylene, 1-butene, and isobutylene. structural units derived from olefins such as; The above-mentioned other structural units may contain one type or a plurality of types.

The content of the other structural units is preferably 50 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, and even more preferably, based on the total structural units of the vinyl alcohol polymer. 10 mol% or less, particularly preferably 5 mol% or less, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, still more preferably 1 mol% or more, still more preferably 2 mol% or more , particularly preferably 3 mol % or more. When the content of the other structural unit is not less than the lower limit value and not more than the upper limit value, it is easy to obtain a more excellent water absorption amount or water absorption rate of the resin for cement admixture of the present invention.

In one aspect of the present invention, from the viewpoint of exhibiting water absorbency in construction or civil engineering structure cement, the vinyl alcohol polymer crosslinked product has an elution rate of 0 to 40% in a cement filter solution. is preferred, 0 to 30% is more preferred, and 0 to 25% is more preferred. If the above elution rate is higher than the upper limit, the effective portion having water absorption capacity will decrease, and the water absorption capacity described below will decrease. There is concern about problems such as a decrease in the water absorption capacity of the gaps. This elution rate is calculated by comparing the pure weight of the crosslinked vinyl alcohol polymer after immersing the crosslinked vinyl alcohol polymer in the cement filter solution at 15 to 25° C. for 24 hours and the weight of the crosslinked vinyl alcohol polymer before immersion. It is a value calculated from the weight of an object and more specifically measured according to the method described in Examples. In addition, as described in Materials and Structures (2018) 51:116, the cement filter solution is obtained by dispersing 5 ion-exchanged water to 1 ordinary Portland cement in a mass ratio, and stirring for 24 hours using a magnetic stirrer. It is an aqueous solution obtained by filtering the slurry, and the water absorption and elution behavior in this aqueous solution mimics the behavior of the vinyl alcohol polymer crosslinked product in the cement paste.

In one aspect of the present invention, from the viewpoint of supplying sufficient water to the surroundings during the curing process, the crosslinked vinyl alcohol polymer preferably has a water absorption capacity of 10 g/g or more in a cement filter solution, more preferably 15 g/g or more, particularly preferably 25 g/g or more. If it is lower than 10 g/g, the amount of water that can be retained by the resin is small, so the amount of water separation is also small. On the other hand, it is preferably 100 g/g or less, more preferably 70 g/g or less, and particularly preferably 40 g/g or less from the viewpoint of mechanical strength such as shape retention during kneading of cement paste. If the particle size is higher than 100 g/g, there is a concern that the swollen resin will not be able to maintain its shape and break when subjected to external pressure during kneading of the cement paste, resulting in a smaller particle size than is desirable. This water absorption capacity is calculated from the amount of water absorbed after the resin is immersed in a cement filter solution at 15 to 25° C. for 24 hours and the weight of the resin before immersion, and more specifically, it is a value measured according to the method described in the Examples. be.

In one aspect of the present invention, the amount of syneresis per 1 g of the crosslinked vinyl alcohol polymer is preferably 7.0 g or more, more preferably 7.5 g or more, from the viewpoint of supplying sufficient water to the surroundings after curing. , particularly preferably 8.0 g or more. The amount of syneresis is calculated from the amount of syneresis when the water absorbent resin saturated and swollen with the cement filter solution is centrifuged at a predetermined rotation speed, and more specifically, it is a value measured according to the method described in the Examples.

The vinyl alcohol-based polymer crosslinked product preferably contains one or more functional groups selected from the group consisting of carboxyl groups, ester groups, sulfonic acid groups, amino groups and salts thereof.

The monomer for introducing the carboxyl group into the cement admixture resin of the present invention is not particularly limited. Mention may be made of salt. When it is desired to introduce a salt of a carboxyl group, the introduction of the carboxyl group may be followed by conversion to a salt.

The monomer for introducing the ester group into the crosslinked vinyl alcohol polymer is not particularly limited, and examples thereof include acrylic acid esters, anhydrides of carboxylic acid monomers, neutralized products, and the like. Methyl, methyl methacrylate, monomethyl maleate, dimethyl itaconate, maleic anhydride, dimethyl mesaconate, dimethyl citraconate, and the like can be used. Moreover, as an ester group, a lactone produced by a dehydration reaction between a hydroxyl group derived from a polyvinyl alcohol-based polymer and a carboxylic acid ester may be included.

The monomer for introducing the sulfonic acid group into the crosslinked vinyl alcohol polymer is not particularly limited, and examples thereof include vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and p-styrenesulfonic acid. etc. can be mentioned. Examples of monomers into which salts thereof are introduced include sodium vinylsulfonate, sodium 2-acrylamido-2-methylpropanesulfonate, and sodium p-styrenesulfonate. When it is desired to introduce a salt of a sulfonic acid group, the sulfonic acid group may be introduced and then converted into a salt.

The monomer for introducing the amino group into the crosslinked vinyl alcohol polymer is not particularly limited, and examples thereof include diallyldimethylammonium chloride, vinyltrimethylammonium chloride, allyltrimethylammonium chloride, and p-vinylbenzyltrimethylammonium chloride. , and 3-(methacrylamido)propyltrimethylammonium chloride. Examples of derivatives of the above-mentioned monomers having an ammonium group include amines of the monomers, such as diallylmethylamine, vinylamine, allylamine, p-vinylbenzyldimethylamine, and 3-(methacrylamide). Propyldimethylamine and the like can be used.

Examples of counter cations of salts of the above functional groups include alkali metal ions such as lithium, sodium, potassium, rubidium and cesium ions; alkaline earth ions such as magnesium, calcium, strontium and barium ions; other metal ions such as aluminum ions and zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions; and the like.

The content of the monomer to be introduced in the vinyl alcohol polymer crosslinked product is 0.1 mol% or more, preferably 1 mol% or more, more preferably 3 mol%, based on the total structural units of the vinyl alcohol polymer. Above, more preferably 4 mol% or more, particularly preferably 5 mol% or more, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less, still more It is preferably 20 mol % or less, particularly preferably 15 mol % or less, and even more preferably 10 mol % or less. When the content of the functional group is at least the lower limit, the vinyl alcohol polymer tends to have an improved water absorption amount or water absorption rate. When the content of the functional group is equal to or less than the upper limit, the vinyl alcohol polymer tends to maintain an excellent liquid absorption amount or liquid absorption rate even when in contact with divalent ions contained in cement. The liquid absorption amount or liquid absorption rate is unlikely to decrease over a long period of time.

The cement admixture resin of the present invention desirably contains one or more carboxylic acid-based monomer structural units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid and derivatives thereof, and is easy to manufacture. From the viewpoint of above, methyl acrylate, methyl methacrylate, monomethyl maleate, dimethyl itaconate, and maleic anhydride are preferred.

The method for producing a cement admixture resin of the present invention preferably includes a step (A) of performing a saponification reaction with 1 part by mass or more and 30 parts by mass or less of a vinyl alcohol polymer before saponification with respect to 100 parts by mass of a solvent. .

From the viewpoint of production efficiency, the amount of polyvinyl acetate, which is a vinyl alcohol polymer before saponification, used in step (A) is 1 part by mass or more, preferably 2 parts by mass or more, and more preferably 100 parts by mass of the solvent. is preferably 3 parts by mass or more. From the viewpoint of forming pores, it is preferably 30 parts by mass or less, preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

As the type of solvent used in the step (A), methanol and ethanol, which are alcoholic solvents, are preferable because the saponification reaction proceeds by transesterification, and among them, methanol is more preferable from the viewpoint of ease of subsequent removal from the resin.

The viscosity-average degree of polymerization of polyvinyl acetate used in step (A) is not particularly limited, but from the viewpoint of ease of production, it is preferably 20,000 or less, more preferably 10,000 or less, even more preferably 4,000 or less, and particularly preferably 3,000. It is below. On the other hand, from the viewpoint of mechanical properties and elution resistance in water of the vinyl alcohol polymer, the viscosity-average degree of polymerization is preferably 100 or more, more preferably 200 or more, and still more preferably 400 or more. The viscosity average degree of polymerization of the vinyl alcohol polymer can be measured by a method based on JIS K6726.

In step (A), it is preferable to add dropwise a basic compound diluted with a solvent to a desired concentration in a uniform solution of polyvinyl acetate. The polyvinyl acetate saponified by this operation is no longer compatible with the solvent and precipitates, thus facilitating the recovery of the product.

In step (A), the moisture content in the system is preferably 0.5% to 1%. If it is less than 0.5%, the reaction proceeds rapidly and is difficult to control.

In step (A), when 98.5 mol % or more is saponified, the molar ratio of the basic compound to vinyl acetate is preferably 0.03 to 0.035 mol %. If it is less than 0.03 mol%, the saponification does not proceed completely, while if it is more than 0.035 mol%, there is concern that the reaction proceeds rapidly and is difficult to control.

In step (A), since the saponification reaction is exothermic, the reaction temperature is 40° C. when adding the basic compound, and 60 to 70° C. after confirming that precipitation of polyvinyl alcohol is almost complete by visual observation. It is preferable to raise the temperature to .

The method for producing the resin for cement admixture of the present invention preferably includes the step (B) of cross-linking the vinyl alcohol polymer by a heterogeneous reaction.

In the step (B), by using a heterogeneous reaction, the pores of the porous polyvinyl alcohol particles can be crosslinked while maintaining the pores, so that the pores having a pore diameter of 0.1 to 10 μm It is easy to obtain a cement admixture resin having a total volume of 0.01 to 2.0 mL/g. More specifically, it is preferable to use a heterogeneous reaction in which the raw material vinyl alcohol polymer is dispersed in a solvent in which the vinyl alcohol polymer is insoluble and reacted with a cross-linking agent. Whether or not the reaction is heterogeneous can be determined by visually observing the system in which the cross-linking reaction is taking place.

In step (B), (1) a raw material vinyl alcohol polymer is dispersed in a solvent in which the vinyl alcohol polymer is insoluble, and reacted with a cross-linking agent dissolved in the solvent; A method of spraying a cross-linking agent or a solution in which the cross-linking agent is dispersed onto the vinyl alcohol polymer of (1) and heating and reacting the same.

In the step (B), the method for producing the crosslinked product of the vinyl alcohol polymer is not particularly limited, but the method (1) is preferable from the viewpoint of ease of control of the reaction. For example, when cross-linking with a polyhydric aldehyde, specifically, at least a portion of the vinyl alcohol units of a vinyl alcohol-based polymer produced by a known technique is heated in the presence or absence of a catalyst, preferably at 80° C. or lower. can be produced by acetalizing at least a portion of vinyl alcohol units with one or more selected from polyhydric aldehyde derivatives at a reaction temperature of .

The dispersion medium used in step (B) is not particularly limited as long as it can swell the vinyl alcohol polymer particles used as the raw material and does not dissolve the particles at the reaction temperature. From the viewpoint of keeping the vinyl alcohol polymer in the form of particles without dissolving it during the reaction, the dispersion medium preferably contains an organic solvent. The content of the organic solvent in the dispersion medium is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly preferably 80% by mass or more. Yes, and may be 100% by mass. When the content of the organic solvent is equal to or higher than the lower limit, fusion of the resin can be suppressed, and the shape of the resin can be maintained. On the other hand, the content of the organic solvent is 95% by mass or less (more preferably 92% by mass or less, still more preferably 90% by mass or less, particularly preferably 85% by mass or less) is also a preferred aspect of the present invention. is. When the content of the organic solvent is equal to or less than the upper limit, the polyvinyl alcohol particles are moderately swollen in the solvent and the carbonyl compound is easily dissolved, so that the interior of the polyvinyl alcohol particles tends to be uniformly acetalized. It is in.

Although the above organic solvent is not particularly limited, for example, dialkyl ketones such as acetone and 2-butanone; nitriles such as acetonitrile; methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, amyl alcohol, isoamyl alcohols such as alcohol, hexanol, cyclohexanol, octanol, tert-butanol; ethers such as 1,4-dioxane, tetrahydrofuran, 1,2-dimethoxyethane and diglyme; diol compounds such as ethylene glycol and triethylene glycol; , N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and other carboxylic acid amides; dimethylsulfoxide, phenol and the like. Among them, considering the ease of removing the solvent from the modified polyvinyl alcohol resin obtained after the heterogeneous reaction, the solubility of the carbonyl compound and the acid catalyst in the solvent, and the industrial availability of the solvent, the organic solvent is dialkyl It is preferably at least one selected from the group consisting of ketones, nitriles, alcohols and ethers, acetone, 2-butanone, acetonitrile, methanol, ethanol, 1-propanol, 2-propanol, tert-butanol, 1,4 - more preferably at least one selected from the group consisting of dioxane and tetrahydrofuran, and at least one selected from the group consisting of acetone, 2-butanone, acetonitrile, methanol, 2-propanol, 1,4-dioxane and tetrahydrofuran More preferably one. These organic solvents may be used singly or in combination of two or more. The solvent used in the heterogeneous reaction may contain water, but if the solvent used in the heterogeneous reaction does not contain water, the organic solvent is selected from the group consisting of dialkylketones, nitriles, alcohols and ethers. is preferably at least one, more preferably an alcohol. Since the interaction between the modified polyvinyl alcohol resin and the solvent changes as the acetalization reaction progresses, a solvent may be added during the reaction for the purpose of controlling the degree of swelling.

When used as a cement admixture resin for building or civil engineering structures of the present invention, there are various forms, including instant cement containing the resin and cement; instant mortar containing the resin, cement and sand; resin, cement, sand and instant concrete, including stone; cement paste, including such resin, cement and water; fresh mortar, including such resin, cement, sand and water; fresh concrete, including such resin, cement, sand, stone and water; mortar containing; and concrete containing the resin.

The above-mentioned sand is sand that passes through a 10 mm mesh sieve and 85% by weight or more of it through a 5 mm mesh sieve, and stone is gravel or grindstone that remains 85% by weight or more through a 5 mm mesh sieve.

There are various methods of mixing when using the cement-mixing resin for building or civil engineering structures of the present invention. For example, a method of adding a resin for

Instant cement is a mixture of the resin and cement, and optionally dry-blended with additives such as an adhesive, a water-retaining agent, and a shrinkage reducing agent. Instant mortar is a mixture of the resin, cement and sand. Instant mortar can be prepared by mixing each material in an arbitrary ratio, and for example, dry blending of 0.004 of the admixed resin for cement and 3 parts of sand to 1 part of cement by volume can be mentioned. Instant concrete is a mixture of the resin, cement, sand and stone. Instant concrete can be prepared by mixing each material in an arbitrary ratio, and for example, dry-blending 0.004 of the admixture resin for cement, 3 sand, and 3 to 6 stones to 1 cement by volume. The amount of the mixed resin for cement is preferably 10 vol % or less, more preferably 1 vol % or less, relative to cement. Moreover, any of them may contain additives such as adhesives, water-retaining agents, and shrinkage-reducing agents, depending on the purpose, and various cements can be used in addition to ordinary Portland cement, depending on the purpose.

The cement paste can be prepared by mixing the instant cement containing the admixture resin for cement and water in an arbitrary ratio, for example, a mixture of 1 part of the instant cement and 1.5 to 1.8 parts of water by volume. is mentioned. Fresh mortar can be mixed with the above instant mortar and water at any ratio. On the other hand, the compounding ratio of sand 2 is preferable. Fresh concrete can be mixed with the above instant concrete and water at any ratio. For example, the volume ratio of cement to 1 part is preferably 3 sand, 3 to 6 stone, and 1.5 to 1.8 water, and if you want to increase strength. is preferably a compounding ratio of 2 parts sand and 4 parts stone to 1 part cement. Cement paste, fresh mortar, and fresh concrete may all contain admixtures such as adhesives, water-retaining agents, and shrinkage reducing agents, depending on the purpose. can be used. In addition, the mortar containing the admixture resin for cement is one in which part or all of the water in the fresh mortar has been consumed by hydration reaction or drying. Furthermore, the concrete containing the admixture resin for cement is one in which part or all of the water in the fresh concrete has been consumed by hydration reaction or drying.

Moreover, the instant cement, instant mortar, instant concrete, cement paste, fresh mortar, fresh concrete, mortar and concrete of the present invention may contain additives within a range that does not impair the effects of the present invention. Examples of additives include swelling agents, quick-setting agents, high-strength admixtures, silica fume, waterproofing materials, AE agents, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, fluidizing agents, hardening Additives commonly used for mixing with cement, such as accelerators, setting retarders, foaming agents, water-inseparable admixtures, hydration heat inhibitors, sticking agents, drying shrinkage reducing agents, antifreeze agents, etc. Polysaccharides such as starch, modified starch, sodium alginate, chitin, chitosan, cellulose and derivatives thereof; polyethylene, polypropylene, ethylene-propylene copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer Polyvinyl chloride, Polycarbonate resin, Polyethylene terephthalate, Polybutylene terephthalate, Polylactic acid, Polysuccinic acid, Polyamide 6, Polyamide 6/6, Polyamide 6/10, Polyamide 11, Polyamide 12, Polyamide 6/12, Polyhexamethylenediamine Terephthalamide, polyhexamethylenediamine isophthalamide, polynonamethylenediamine terephthalamide, polyphenylene ether, polyoxymethylene, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, polyurethane, polyvinyl alcohol, ethylene-vinyl alcohol Polymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyacrylic acid, polyacrylic acid ester, polyacrylate, polymethacrylic acid, polymethacrylic acid ester, polymethacrylate, ethylene-acrylic acid copolymer , ethylene-acrylate copolymers, ethylene-acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methacrylate copolymers, ethylene-methacrylate copolymers, and other resins; natural Rubber, synthetic isoprene rubber, chloroprene rubber, silicone rubber, fluororubber, urethane rubber, acrylic rubber, styrene thermoplastic elastomer, olefin thermoplastic elastomer, ester thermoplastic elastomer, urethane thermoplastic elastomer, amide thermoplastic elastomer kaolinite, smectite, montmorillonite, sericite, chlorite, glauconite, talc, natural zeolite, synthetic zeolite, and other clay minerals; and sand. These may contain 1 type independently, or may contain multiple types.

There are various kneading methods, such as manual mixing using a boat or construction wheelbarrow, using a concrete mixer, or using a mixer truck. After mixing cement with sand or stone, water is added and kneaded, and the mixed resin for cement may be added in a powder state to the kneaded product, or a part of the resin in a powder state may be added in advance. It may be added after it is allowed to absorb water and swell.

Moreover, it can be applied not only to the laying method in which cement paste is poured into a general formwork, but also to shotcrete. There are no particular restrictions on the type of cement to be applied, and Portland cement such as ordinary Portland cement, high-early strength Portland cement, moderate heat Portland cement, white Portland cement, mixed cement such as blast furnace cement, silica cement, fly ash cement, alumina It can be applied to special cement such as cement.

Since the resin for cement admixture of the present invention exhibits excellent water absorption and separation properties as a cement admixture, it is suitable for use in construction and civil engineering structures. Examples of buildings in which the cement admixture resin of the present invention is used include buildings, houses, stadiums, and the like. Examples of civil engineering structures include viaducts such as expressways and trains, tunnels, slopes such as expressways, dams, roads, and harbors.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and the like, but the present invention is not limited to such examples and the like.

(Measuring method)

(1) Preparation of Cement Filter Solution An aqueous solution obtained by dispersing 150 g of ordinary Portland cement of Taiheiyo Cement Co., Ltd. in 750 g of deionized water and filtering the slurry after stirring for 24 hours using a magnetic stirrer was used. . The pH of this cement filter solution was 12.54 to 12.79 when measured at 22° C. with a pH meter manufactured by HORIBA, Ltd. The solution prepared by this method was used in the following measurements (3) to (5).

(2) Cumulative pore volume 0.25 g of the resin obtained in Examples and Comparative Examples was placed in a standard 5 cc powder cell (stem volume 0.4 cc), and the initial pressure was 2.5 kPa. It was measured using a pore size distribution analyzer (Autopore 9520 manufactured by Shimadzu Corporation). The mercury parameters were a mercury contact angle of 130 degrees and a mercury surface tension of 485 hynes/cm.

(3) Elution rate Classified resin for cement admixture of 100 μm to 212 μm and a nylon mesh tea bag (size: 7 cm × 12 cm, opening: 57 μm) sealed on three sides were dried under reduced pressure overnight at 40 ° C. (0.67 MPa). The tare weight of the tea bag was measured, 0.2 g of resin for cement admixture was put into the tea bag, and the remaining one side was heat-sealed. The tea bag was immersed in 500 mL of a cement filter solution at 22°C for 24 hours, then taken out and again dried in a vacuum dryer overnight at 40°C under reduced pressure (0.67 MPa). The resin was taken out from the teabag and weighed, and the elution rate was calculated by the following formula. Four tea bags were prepared for each type of resin and tested, and the average value was adopted.
(Elution rate [%]) = 100 × [{(weight of resin before immersion in cement filter solution [g]) - (weight of resin after immersion in cement filter solution and drying [g])}/ (Weight of resin before immersion in cement filter solution [g])]
However, the elution rate was not calculated for samples that increased in weight after drying due to weight increase due to counter-cation replacement of the resin and weight increase due to precipitation of calcium carbonate on the resin surface by immersion in the cement filter solution.

(4) Water absorption capacity Calculated according to the method described in Materials and Structures (2018) 51:116. As in the elution rate measurement in (3), after drying the tea bag and the resin for cement admixture and immersing it in a cement filter solution, the tea bag containing the resin for cement admixture was taken out and placed on a paper waste for 30 seconds to remove excess water. excluding. The weight was measured and taken as the weight of the wet resin and the tea bag. Then, the water absorption capacity was calculated according to the following formula. As in (3) dissolution rate test, the average value of 4 samples was used in this test as well.
(Water absorption capacity [g / g]) = {(weight of wet resin and tea bag [g]) - (weight of tea bag and dry resin before immersion in cement filter solution [g]) - (tea bag liquid absorption amount [g])} / (weight of dry resin [g])
The amount of liquid absorbed by the tea bag was measured by drying the same tea bag under reduced pressure (0.67 MPa) at 40° C. overnight, immersing it in a cement filter solution for 30 seconds, taking it out, placing it on a paper waste for 30 seconds, and surplus. After removing the water, the weight was measured and calculated according to the following formula. This test was performed on 10 teabags, and the average value was adopted.
(Liquid absorption amount of tea bag [g]) = (Weight of tea bag containing water [g]) - (Weight of tea bag before immersion in cement filter solution [g])

(5) Amount of water separation per 1 g of resin (4) Immerse about 3 g of cement admixture resin of 100 μm to 300 μm classified in a cement filter solution that exceeds the amount of water absorption capacity obtained in (4), and leave to stand for 16 hours. After that, it was filtered through a nylon mesh with an opening of 57 μm to prepare a gel. A 3 mL plastic syringe was filled with a 10 μm caliber membrane filter sandwiched between two nonwoven fabrics, and 3 mL of the gel was collected and added, followed by centrifugation at 2200 rpm. From the ratio of the cement filter solution that flowed out at this time (flowed out solution), the water separation rate was calculated as follows, and the water separation amount per 1 g of resin was calculated from the following formula.
(Amount of solution in gel [g]) = (gel weight [g]) - {(gel weight [g]) ÷ (water absorption capacity obtained in (3) [g/g])}
(Water separation rate [%]) = (Amount of solution [g] that flowed out) / (Amount of solution in gel [g]) x 100
(Water separation amount [g] per 1 g of resin) = (Resin 1 [g]) x (Water absorption capacity [g/g] obtained in (3)) x (Water separation rate [%])
In the above, the gel weight is the weight [g] of 3 mL of gel.

[Production Example 1]
9030 g of vinyl acetate, 18.15 g of methyl acrylate, and 3810 g of methanol were introduced into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and an initiator addition port, and reacted for 30 minutes while nitrogen bubbling. The inside of the vessel was replaced with an inert gas. Heating of the reactor was started using a water bath, and when the internal temperature of the reactor reached 60° C., 2.40 g of azobisisobutyronitrile (AIBN) was added as an initiator to initiate polymerization. . Appropriate sampling is performed, the progress of polymerization is confirmed from the solid content concentration, and the consumption rate, which is the total mass of vinyl acetate and methyl acrylate consumed by polymerization with respect to the total mass of vinyl acetate and methyl acrylate introduced, is calculated. asked. When the consumption rate reached 4% by mass, the internal temperature of the reactor was cooled to 30° C. to terminate the polymerization. A vacuum line was connected and residual vinyl acetate was distilled off under reduced pressure together with methanol at 30°C. While visually confirming the inside of the reactor, when the viscosity increased, methanol was added as appropriate while distillation was continued to obtain polyvinyl acetate containing 5.2 mol % of acrylic acid-derived structural units. The content of acrylic acid-derived structural units was measured using solid-state ¹³ C-NMR.
Next, 360 g of the obtained acrylic acid-derived structural unit-containing polyvinyl acetate and 6552 g of methanol were added to the same reactor as above to dissolve the acrylic acid-derived structural unit-containing polyvinyl acetate. A water bath was used to start heating the reactor and the reactor was heated with stirring until the internal temperature of the reactor reached 70°C. 280.8 g of a methanol solution of sodium hydroxide (meta-caustic, concentration 15% by mass) was added thereto, and saponification was performed at 70° C. for 2 hours.
The solution after saponification was filtered and vacuum-dried at 40° C. to obtain 165 g of polyvinyl alcohol (hereinafter referred to as polyvinyl alcohol (a)). The content was 5 mol %, and the content of acrylic acid-derived structural units was 5.2 mol %.

[Production Example 2]
A polymerization vessel (continuous polymerization apparatus) equipped with a reflux condenser, a raw material supply line, a thermometer, a nitrogen inlet, and a stirring blade; An apparatus equipped with a stirring blade was used. Vinyl acetate (VAM) (656 L/H), methanol (MeOH) (171 L/H), a 20% methanol solution of monomethyl maleate (MMM) as a modified species (101 L/H), and 2,2 as an initiator were added to the polymerization tank. A 2% methanol solution (25 L/H) of '-azobis(4-methoxy-2,4-dimethylvaleronitrile) (AMV) was continuously supplied using a metering pump. The polymerization liquid was continuously taken out from the polymerization tank so that the liquid level in the polymerization tank was constant. The polymerization rate of vinyl acetate in the polymerization solution taken out from the polymerization tank was adjusted to 40%. The residence time in the polymerization tank was 4 hours. The temperature of the polymerization solution taken out from the polymerization tank was 63°C. The polymerization liquid was taken out from the polymerization tank, and methanol vapor was introduced into the polymerization liquid to remove unreacted vinyl acetate, thereby obtaining a methanol solution of polyvinyl acetate (PVAc) (concentration: 35%).
Desired amounts of water and methanol are added to the methanol solution of polyvinyl acetate to prepare a polyvinyl acetate (PVAc)/methanol solution (concentration of 32% by mass) having a water content of 1.3% by mass, which is a raw material solution for saponification. did. A sodium hydroxide/methanol solution (concentration 4% by mass), which is a saponification catalyst solution, was added so that the molar ratio of sodium hydroxide to vinyl acetate units in the PVAc was 0.10. The saponification raw material solution and the saponification catalyst solution were mixed using a static mixer. The resulting mixture was placed on a belt and held at a temperature of 40° C. for 18 minutes to allow the saponification reaction to proceed. The gel obtained by the saponification reaction was pulverized and deliquored. 600 kg/hr (resin content) of the obtained polyvinyl alcohol powder was continuously supplied to a dryer having a jacket temperature of 105°C. The average residence time of the powder in the dryer was 4 hours. After that, pulverization was performed to obtain polyvinyl alcohol (b). The resulting polyvinyl alcohol (b) had a viscosity average degree of polymerization of 1200, a degree of saponification of 96.0 mol %, and a content of monomer units having two carboxyl groups of 4.0 mol %.

[Example 1]
445.5 g of methanol, 47.4 g of pure water, 1.206 g of 25% by mass glutaraldehyde aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and polyvinyl 150 g of alcohol (a) was introduced and stirred at 23° C. to disperse polyvinyl alcohol (a). A mixed liquid of 5.66 g of a 47% by mass sulfuric acid aqueous solution and 3 g of pure water was added dropwise over 10 minutes, and the temperature was raised to 65° C. for cross-linking reaction for 6 hours. After the reaction, the polymer was taken out by filtration, and washed by dispersing the filtered polymer in 220 g of methanol, stirring for 30 minutes, and filtering. Washing was repeated 7 times.
The washed polymer was introduced into a three-necked separable flask equipped with a reflux condenser and a stirring blade, 245 g of methanol, 40.8 g of pure water, and 24.35 g of 50% by mass potassium hydroxide were added, and the mixture was stirred at 65°C. It was reacted for 2 hours. After the reaction, the polymer was taken out by filtration, and washed by dispersing the filtered polymer in 330 g of methanol, stirring for 30 minutes, and filtering. Washing was repeated 7 times. The washed polymer was vacuum dried at 40° C. for 12 hours to obtain the desired resin for cement admixture. The content of acrylic acid-derived structural units was 5.2 mol % with respect to the total structural units of the resin. The above-mentioned tests (2) to (5) were carried out on the cement admixture resin thus obtained, and each measurement was performed. Table 1 shows the results.

[Example 2]
445.5 g of methanol, 47.4 g of pure water, 1.206 g of 25% by mass glutaraldehyde aqueous solution, and 150 g of polyvinyl alcohol (a) were introduced into a three-necked separable flask equipped with a reflux condenser and a stirring blade. °C to disperse the polyvinyl alcohol. A mixed liquid of 5.66 g of a 47% by mass sulfuric acid aqueous solution and 3 g of pure water was added dropwise over 10 minutes, and the temperature was raised to 65° C. for cross-linking reaction for 6 hours. After the reaction, the polymer was taken out by filtration, and washed by dispersing the filtered polymer in 220 g of methanol, stirring for 30 minutes, and filtering. Washing was repeated 7 times. The washed polymer was vacuum dried at 40° C. for 12 hours to obtain the desired resin for cement admixture. The obtained resin was subjected to the above-mentioned tests (2) to (5), and each measurement was performed. Table 1 shows the results.

[Comparative Example 1]
The desired cement admixture resin was obtained in the same manner as in Example 1, except that polyvinyl alcohol (a) was changed to polyvinyl alcohol (b) and the amount of the 25% by mass glutaraldehyde aqueous solution was changed to 1.118 g. I made a measurement. Table 1 shows the results.

[Comparative Example 2]
500 g of polyvinyl alcohol (b) was weighed into an eggplant flask and heat-treated at 130° C. for 5 hours under reduced pressure using an evaporator to carry out a cross-linking reaction to obtain the desired resin for cement admixture, which was measured. When measuring the amount of syneresis per 1 g of resin, the resin was dissolved in the cement filter solution when the sample was prepared, so the amount of syneresis could not be measured. Table 1 shows the results.

[Comparative Example 3]
As a general-purpose water-absorbing resin, using Aqua Keep 10-SHPF (acrylic acid-sodium acrylate copolymer crosslinked product) manufactured by Sumitomo Seika Co., Ltd., the above-mentioned (2) to (5) tests were performed. , each measurement was performed. Table 1 shows the results.

As shown in Examples 1 and 2, the crosslinked vinyl alcohol polymer of the present invention, which satisfies the cumulative pore volume, has a low elution rate and a high water absorption capacity in a cement filter solution, that is, in an alkaline aqueous solution. , It was shown to express water syneresis, which is considered to be correlated with the crack suppression of concrete in architectural or civil engineering structures. On the other hand, Comparative Example 1, in which the saponification process was different and the amount of accumulated pore volume was small, hardly showed syneresis. When the cross-linking method was different (Comparative Example 2), the gel strength was low and the water separation test could not be performed. Moreover, when a general-purpose water-absorbing resin was used (Comparative Example 3), almost no cement solution could be absorbed, and no syneresis effect was exhibited.

Since the cement admixture resin for architectural or civil engineering structures of the present invention is excellent in water repellency, it can supply sufficient water to the voids generated by volumetric shrinkage due to the hydration reaction of cement and water, and self-shrinkage. Since it is possible to suppress cracks caused by erosion, it can be suitably used for improving the strength of mortar and concrete.

Claims (15)

A resin for admixture with cement for building or civil engineering structures comprising a crosslinked vinyl alcohol polymer, wherein the cumulative pore volume of pores having a pore diameter of 0.1 to 10 μm is 0.01 to 2.0 mL/g. A resin for cement admixture. 2. The cement admixture resin according to claim 1, wherein the crosslinked structure of said vinyl alcohol polymer crosslinked product is derived from a polyhydric aldehyde compound or a polyhydric epoxy compound. 3. The vinyl alcohol-based polymer crosslinked product according to claim 1 or 2, wherein the crosslinked product contains one or more functional groups selected from the group consisting of carboxyl groups, ester groups, sulfonic acid groups, amino groups and salts thereof. Resin for cement admixture. 4. The vinyl alcohol-based polymer crosslinked product according to claim 3, which contains one or more carboxylic acid-based monomer structural units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and derivatives thereof. cement admixture resin. The cement admixture resin according to any one of claims 1 to 4, wherein the carboxylic acid-based monomer unit content is 0.1 mol% to 50 mol%. The cement admixture resin according to any one of claims 1 to 5, comprising a step of performing a saponification reaction with 1 part by mass or more and 30 parts by mass or less of the vinyl alcohol polymer before saponification with respect to 100 parts by mass of the solvent. manufacturing method. 5. The method for producing a cement admixture resin according to any one of claims 1 to 4, comprising a step of cross-linking the vinyl alcohol polymer by a heterogeneous reaction. Instant cement comprising the cement admixture resin according to any one of claims 1 to 5 and cement. An instant mortar comprising the cement admixture resin according to any one of claims 1 to 5, cement and sand. Instant concrete comprising the cement admixture resin according to any one of claims 1 to 5, cement, sand and stone. A cement paste comprising the instant cement of claim 8 and water. Fresh mortar comprising instant mortar according to claim 9 and water. Fresh concrete comprising the instant concrete of claim 10 and water. A mortar containing the cement admixture resin according to any one of claims 1 to 5. Concrete containing the cement admixture resin according to any one of claims 1 to 5.