JPH0426535A - Cement admixture and polymer cement composition - Google Patents

Abstract

PURPOSE:To improve initial shrinkage by adding a cement admixture based on an expandable admixture having a specified specific surface area and a polymer to cement. CONSTITUTION:An expandable admixture having >=2m<2>/g specific surface area obtd. by crushing materials such as hauyne and calcium oxide and an emulsion of synthetic resin such as an ethylene-vinyl acetate copolymer and/or latex of synthetic rubber such as a styrene-butadiene copolymer are used as principal components and 1-5 pts.wt. defoaming agent such as alcohol based on 100 pts.wt. solid matter of the polymer and a dispersant such as a salt of a naphthalenesulfonic acid-formaldehyde condensation product are added to the principal components to prepare a cement admixture. This cement admixture is added to cement such as Portland cement so as to regulate the amt. of the expandable admixture to 1-25 pts.wt. per 100 pts.wt. of the cement, that of the emulsion and/or the latex to 1-25 pts.wt. and that of the dispersant to 0.02-5 pts.wt. They are kneaded and a polymer cement compsn. having improved initial shrinkability is obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a cement admixture for polymer cement with improved initial shrinkage and a polymer cement composition using the same. Cement admixtures for polymer cement and polymer cement compositions using the same are used in a wide variety of applications, including wall materials, repair materials, waterproofing materials, high-quality and highly durable concrete and grout materials, and building materials. Regarding.

(Prior art and its problems) Polymer cement has been widely used for the purpose of improving adhesiveness, workability, cracking resistance, etc.

However, among these, when a polymer containing a hydrophilic 7-mer in the copolymer composition is added, rapid shrinkage occurs at the initial stage, and in concrete and grout materials, There was a problem that a sound structure could not be obtained due to the occurrence of gaps.

Due to its excellent density and cracking resistance, polymer cement has recently been considered as a new technology for use in highly durable concrete and hyper-performance concrete, which does not require compaction. Considering the development in these fields, it is strongly desired to improve this initial shrinkage and prevent uneven settlement.

The present inventors conducted various studies to solve the above-mentioned problems, and as a result, it was possible to solve the above-mentioned problems by using a specific expandable admixture, and to provide a cement composition with less initial shrinkage. Having discovered this, we have completed the present invention.

(Means for Solving the Problems) That is, the present invention is a cement admixture mainly comprising an expandable admixture having a specific surface area of 2rrf/g or more and a polymer, and further comprising a cementitious substance and the cement. A polymer cement composition comprising an admixture.

The present invention will be explained in detail below.

In terms of components, the expandable admixture according to the present invention includes align mineral-based, calcium oxide-based, calcined mineral-based calcium aluminate-CaSO, which is crystalline or amorphous, or a mixture of both. Ettringite and C, which are expandable hydrates by reaction, such as CaSO4 and CaSO4
It generates a (OH) z, and also includes those that generate hydroxides such as iron powder. Among these, it is preferable to use Align mineral type and calcium oxide type, which are commonly used as expansion materials, from the viewpoint of safety.
Commercially available products such as AJ and Onoda Cement Product Name [Onoda Exban] can be used as ingredients.

The expandable admixture according to the present invention is pulverized to have a large specific surface area. Normally, the specific surface area of commercially available inflatable materials measured by gas adsorption method does not exceed 2rrf/g.
The specific surface area of the expandable admixture according to the present invention is 2 rd/g or more, preferably 4 rrT/g or more.

The amount of expandable admixture used is linked to the amount of polymer used, and typically increases as the amount of polymer used increases.

Generally, 1 to 1 to 100 parts by weight of cementitious material
About 25 parts by weight is preferred. If it is less than 1 part by weight, the effect of reducing shrinkage is small, and if it exceeds 25 parts by weight, expansion and destruction may occur over a long period of time.

Cementitious substances used in the present invention include various types of Portland cement such as normal, early strength, super early strength, sulfate resistant, white, etc., various mixed cements made by mixing these Portland cements with pozzolan substances, alumina cement, and Examples include low heat generation cement and ultra-low heat generation cement.

When using alumina cement as a cementitious material,
As a hardening regulator for alumina cement, inorganic salts such as various sulfates, nitrates, carbonates, and lithium salts, as well as CaC1z
, Ca (OH) z, inorganic substances such as borax and boric acid,
Furthermore, one or more organic acids or salts thereof such as citric acid, triboIJ IJ :/[, birophosphoric acid, tartaric acid, and gluconic acid can be used.

The amount of hardening modifier used is 0.005 to 100 parts by weight of cementitious material whose main component is alumina cement.
2 parts by weight is preferred.

Further, it is also possible to use the above-mentioned cementitious material together with an ultrafine powder and a dispersant whose main components are a naphthalene sulfonic acid formalin condensate, a melamine resin sulfonate, a purified lignin sulfonate, or the like.

Generally, the average particle size of cementitious materials is on the order of IOμ. The ultrafine powder is at least one order of magnitude smaller than the cementitious material, and it is preferable from an economic point of view to use finely pulverized products such as silica fume, blast furnace slag, and fly ash.

When using a cementitious material, ultrafine powder, and a dispersant, if 1 to 3 parts by weight of the dispersing agent is added to 100 parts by weight of the cementitious material, the amount of water used will be 40 parts by weight per 100 parts by weight of the cementitious material. It is possible to ensure very good fluidity even if the amount is less than 30%.

It is also possible to use commonly used admixtures mainly composed of blast furnace slag and fly ash, as well as other admixtures such as setting retarders and accelerators.

The polymer according to the present invention is not particularly limited as long as it is primarily developed for mixing with cement, and either powder or liquid form can be used.

In the present invention, synthetic resin emulsilane and/or synthetic rubber latex are used.

The present invention further uses an expandable admixture to maintain the crack resistance and adhesion properties characteristic of conventional polymer cement systems, and to improve initial large shrinkage.

The synthetic resin emulsion generally refers to vinyl polymers, and examples include ethylene-vinyl acetate copolymer systems, vinylidene chloride systems, acrylic systems, and vinyl chloride systems.

Synthetic rubber latex is generally a synthetic rubber compound synthesized from diene monomers, including styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NB), and methyl methacrylate-butadiene copolymer (NB). M8), polybutadiene type, polychloroprene type, etc.

Among these, polymers containing highly hydrophilic hetamine-1, such as vinyl acetate, etc., in their copolymer composition are particularly
The initial shrinkage immediately after water injection is extremely large.

Although the reason for this is not certain, it is assumed that the cause is elution of the remaining monomer or contraction of the polymer due to osmotic pressure effects.

Usually, when these synthetic resin emulsions and synthetic rubber latexes are produced by emulsion polymerization, it is possible to use a water-soluble polymer that acts as a protective colloid as an emulsion stabilizer.

Here, polyvinyl alcohol (
PVA) and hydroxyethyl cellulose (HEC).

Furthermore, in the present invention, when a dispersant is used in combination, the use of these water-soluble polymers as emulsion stabilizers tends to have an adverse effect on fluidity.

In addition, when these water-soluble polymers are not used as protective colloids, it is necessary to use a surfactant as an emulsion stabilizer, or to control the polymerization initiator concentration because the water-soluble oligomers formed during the polymerization process act as emulsion stabilizers. To make it higher,
Preference is given to using a polymerization initiator.

As the surfactant, anionic, cationic and nonionic surfactants can be used.

Examples of anionic surfactants include sodium vinyl sulfonate, sodium styrene sulfonate, sodium 2-sulfoethyl methacrylate, sodium allyl alkyl sulfosuccinate, higher alcohol sulfate ester sodium salt, and polyoxyethylene alkylphenyl ether sulfate ammonium salt. It will be done.

Further, examples of the cationic surfactant include 2-aminoethyl methacrylate hydrochloride and 2-hydroquine-3-trimethylaminopropyl methacrylate chloride.

Furthermore, examples of nonionic surfactants include polyoxyethylene methacrylate, polyoxyethylene polyoxypropyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene styryl phenyl ether.

The amount of surfactant used is 0.00 parts by weight per 100 parts by weight of the solid content of the polymer. About 1 to 10 parts by weight of O is preferable.

If it is less than 0.01 parts by weight, it is difficult to carry out emulsion polymerization, and if it exceeds 10 parts by weight, it tends to have an adverse effect on the weather resistance, alkali resistance, water resistance, etc. of the polymer.

Examples of polymerization initiators include persulfates such as potassium persulfate as electrolytic groups, 2,4'azobis-cyanohaleric acid having a carboxyl group, and 2,2'' having an amino group.
-Azobisisobutyramideine salts and the like.

The amount of the polymerization initiator used is preferably about 0.01 to 1 part by weight based on 100 parts by weight of the solid content of the polymer.

If it is less than 0.01 part by weight, it is difficult to carry out emulsion polymerization, and if it exceeds 1 part by weight, it tends to have an adverse effect on the weather resistance, alkali resistance, water resistance, etc. of these polymers.

The particle size of the solid content of the polymer thus obtained is 0.
．． It is about 05 to 5μ.

In order to impart fluidity to these polymers, it is preferred to copolymerize with other comonomers.

These comonomers include vinyl propionate, vinyl cabrylate, vinyl ester, vinyl versatate, dibutyl maleate, diethylhexyl acrylate, ethyl acrylate (EA), butyl acrylate (BA), and ethylhexyl acrylate (EHA). Examples include acrylic.

Note that it is naturally possible to copolymerize a combination of these comonomers.

The amount of these comonomers used is preferably 10 to 80 parts by weight per 100 parts by weight of the polymer.

In the ethylene-vinyl acetate copolymer system, it is preferable to use 20 to 80 parts by weight of vinyl acetate per 100 parts by weight of the polymer in order to obtain adhesive properties and crack resistance. If it is less than 20 parts by weight, adhesive strength and cracking resistance tend to be poor, and if it exceeds 80 parts by weight, alkali resistance tends to be poor.

The amount of the polymer used is preferably 1 to 25 parts by weight, more preferably 2 to 20 parts by weight, based on solid content, based on 100 parts by weight of the cementitious material. If it is less than 1 part by weight, the adhesion and cracking resistance tend to be poor, and if it exceeds 25 parts by weight, the mechanical properties tend to be poor.

The method of mixing the expandable admixture with the polymer is not particularly limited; it may be premixed in advance, or it may be added during mortar or concrete production, and the mixing order is also not particularly limited. It's not a thing.

Note that when a polymer is added to a cementitious material, air bubbles are entrained and the strength and density of the cured product are reduced, so it is preferable to use an antifoaming agent or the like in combination with the polymer.

Antifoaming agents include oils and fats such as sesame oil, fatty acids such as stearic acid, alcohols such as octyl alcohol, partial esters of polyhydric alcohols and fatty acids such as sorbitan fatty acid ester, polyoxyethylene polyoxypropylene ether, Examples include paraffin type and silicone type. Specifically, alcohol-based products include "Karalin 302" manufactured by Sanyo Chemical Industries, Ltd.;
Polyoxyethylene polyoxypropylene ether-based products include Toho Chemical's product name "Pronal 502" and Kao's product name F-Antihome E-20J, and silicone-based products include Toshiba Silicone's product name rTSA 7.
Examples include 32J.

The amount of antifoaming agent used is preferably about 1 to 531 parts by weight based on 100 parts by weight of the solid content of the polymer.

Furthermore, by using a dispersant in combination with a polymer that does not contain a water-soluble polymer as an emulsion stabilizer, fluidity is not impaired even when the water-cement ratio is lowered, and the product has excellent adhesion, denseness, and cracking resistance. It is also possible to create high strength polymer cement compositions with improved durability.

Examples of dispersants include salts of naphthalene sulfonic acid formaldehyde condensates, salts of melamine sulfonic acid formaldehyde condensates, lignin sulfonates, high molecular weight lignin sulfonates, and polycarboxylic acid salts.Specifically, naphthalene As the salt of sulfonic acid formalin condensate, Denka Kagaku Kogyo ■ [Denka PT-500J and Daiichi Kogyo Seiyaku ■]
Product names such as ``Cellflow 110PJ'' manufactured by Nihon Sika Corporation are used as the salts of melamine sulfonic acid formaldehyde condensed metals, while product names manufactured by Nippon Sika FPJ and product names manufactured by Showa Denko ``Melment'' are used as lignin sulfonate salts. National Policy Valve ■Product name F Sunflow Examples include Nippon Shokubai Chemical Co., Ltd. product name r600sJ, which is an addition reaction of alkylene imine and/or alkylene oxide to a carboxyl group-containing polymer, and a hydrolyzate of a copolymer of olefin and ethylenically unsaturated dicarboxylic acid anhydride. A Nippon Zeon product name [Work 500] and rM40
J. Hydrolysates and anhydrides such as copolymers of olefins and maleic anhydride, styrene, or copolymers of other copolymerizable monomers and maleic anhydride, which are gradually hydrolyzed by alkali from cement. Examples include sustained-release types that exhibit fluidity due to the above-mentioned properties, and even if two or more of these are used in combination, the effect of improving fluidity can naturally be obtained.

In addition to being added in the form of a powder, the dispersant can also be added in the form of a liquid.

The amount of the dispersant to be used depends on the water-cement ratio, but is preferably 0.02 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, based on 100 parts by weight of the cementitious material.

If it is less than 0.02 parts by weight, it is difficult to obtain good fluidity, and even if it exceeds 5 parts by weight, it is difficult to obtain better fluidity.

In the present invention, it is possible to add aggregate having a larger particle size than the various materials mentioned above.

In the present invention, aggregate refers to one with a particle size exceeding 100μ, and general sand, gravel, lightweight aggregate, etc. can be used.
Furthermore, Mohs hardness is 6 or more or Nubu indenter hardness is 700 kg.
Of course, it is also possible to use hard aggregate selected on the basis of f/a+m2 or higher.

In addition, glass, metal, etc. can also be used as aggregates.

The amount of aggregate used is preferably up to about 1,000 parts by weight per 100 parts of the cementitious material.

However, this does not apply to special construction methods such as pre-packed construction methods and post-packed construction methods.

There are no particular restrictions on the mixing method and order of addition of each material as long as each material is kneaded uniformly.

As for the molding method of the H product, the molding method and construction method used for ordinary cement-based building materials, mortar concrete, etc. can be used.

Furthermore, in the present invention, the above-mentioned materials are steel frames, reinforcing bars, and FR.
It can also be used in conjunction with reinforcing materials and fibers such as P-Rondo.
It is also possible to reinforce tensile strength, bending strength, etc.

As the reinforcing material, it is also possible to use conventionally used steel rods, molded bodies made of alumina fiber, etc., and these reinforcing materials are often necessary, especially for large-sized products.

Examples of fibers include fibers produced by chatter cutting of cast iron, metal fibers such as steel fibers and stainless steel fibers, various natural or synthetic mineral fibers such as asbestos, ceramic fibers, synthetic resin fibers such as polypropylene, and alumina fibers, carbon fibers, and glass fiber.

The curing conditions for the cement mixture obtained by kneading each material in this way are not particularly limited, but from the viewpoint of the reaction of the expandable admixture, it is preferable to perform wet curing at the initial stage.

Cement products manufactured by the above method are used for high quality, highly durable concrete structures, bi-performance concrete, repair materials such as grouting for delaminated parts of concrete structures and anti-corrosion coating for corroded reinforcing bars, and roads. Our products cover a wide range of products, including paving materials, waterproofing materials for flooring and roof slabs, adhesives for tiles, decorative finishing materials, anti-corrosion materials such as joint materials for chemical factory floors and acid-resistant tiles, desokika herring materials, and various building materials.

(Example) The present invention will be further explained below with reference to Examples.

Example 1 Initial curing shrinkage was measured using an automatic curing shrinkage measuring device (manufactured by Tokyo Riko).

That is, about 80 g of mortar, which has been kneaded to a constant temperature, is placed in a thin film rubber bag (manufactured by Okamoto Riken Rubber), sealed, and placed in a 300 cc airtight container filled with water.
It was connected to the a+m capillary with a tube. When the mortar in the rubber bag expands or contracts, the water interface in the capillary moves up and down, which is detected by an optical sensor.
Inflation and deflation were measured by automatically detecting their movements.

The composition used was 83 parts by weight of cementitious material, 1 part by weight of ultrafine powder.
7 parts by weight, 1.5 parts by weight of water reducing agent, 122 parts by weight of sand, 10 parts by weight of polymer, 0.3 parts by weight of antifoaming agent, and 35 parts by weight of water, to reduce the effects of breathing etc. And so. The results are shown in Table-1.

Materials used: Cementitious material: White Portland cement manufactured by Chichibu Cement Co., Ltd., specific gravity 3.15 Ultra-fine powder Silica hume manufactured by Nippon Chemical Co., Ltd., specific gravity 2.1 Dispersant; Part name F Cellflow 110P manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
J sand: Silica sand No. 7, specific gravity 2.6 Antifoaming agent: Toho Chemical product name "Pronal 503" Polymer A: ethylene/vinyl acetate/normal butyl acrylate) = 16/42/42, nonionic emulsion stabilizer of polyoxyethylene phenyl ether
Add 8 parts by weight to 1 part by weight of OO, charge water, vinyl acetate, normal butyl acrylate, and emulsion stabilizer into a stainless steel autoclave, and heat to 60°C while stirring.
After raising the temperature to °C, a predetermined amount of ethylene was injected under pressure. Next, ammonium persulfate was added to start polymerization, and the polymerization was carried out until the residual monomer amount was 0.5% by weight or less, and then cooled.

Expandable admixture a: manufactured by Dendenki Kagaku Kogyo, trade name Denka C3
Using a surface area measurement device manufactured by AJ and Yuasa Ionics,
Specific surface area 1.3 rd/g by gas adsorption method B: Pulverized product of expandable admixture a, specific surface area 2.5rd/g C: Pulverized product of expandable admixture a, specific surface area 4.5 is 7g Table ( Effects of the Invention) It has become possible to provide a cement admixture and a polymer cement composition that have significantly improved initial shrinkage without impairing the cracking resistance and adhesiveness that polymer cements have conventionally had.

Claims (2)

[Claims] (1) An expandable admixture with a specific surface area of 2 m^2/g or more,
Cement admixture whose main component is polymer. (2) A polymer cement composition comprising a cementitious material and the cement admixture according to claim 1.