JPH07121823B2 - Lady-Mixed Concrete Composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ready-mixed concrete composition, and more specifically, to a decrease in workability of a concrete, mortar, or paste which is a hydraulic cement mixture with time. The present invention relates to a ready-mixed concrete composition that can prevent and improve its workability and workability.

[Prior Art] Conventionally used cement dispersants are ligninsulfonic acid (salt), oxycarboxylic acid (salt), naphthalenesulfonic acid formalin condensate (salt), melaminesulfonic acid formalin condensate (salt). , Polycarboxylic acid (salt)
Etc. In addition, the cement dispersant used in the ready-mixed concrete composition is mostly lignin sulfonate, which is called AE water reducing agent.

Each of these admixtures causes a decrease in the workability of concrete, mortar, or paste with time (hereinafter referred to as slump loss), although to some extent. For this reason, it is possible to reduce the amount of water reduction for concrete that does not contain chemical admixtures (hereinafter referred to as plain concrete), or to add these cement dispersants both at the ready-mixed concrete plant and at the construction site. ing.

Among these, polycarboxylic acid salt has a characteristic that so-called slump loss is extremely small, but in a concrete with 15% or more water reduction compared to plain concrete, with a normal addition amount, slump loss is large, and ready-mixed concrete When manufactured in factories, slump loss often occurs during transportation, which often interferes with construction.

[Problems to be solved by the invention]

In order to solve these problems, it is also considered that excessive addition of cement dispersant gives fluidity of slump loss in the initial stage and makes the fluidity such that concrete after a certain period of time can be easily placed. . However, in this method, the dispersion state of the initial concrete is generally too strong,
Concrete is not preferable because it is separated into aggregate and cement paste.

[Means for solving problems]

The present invention has been made to improve the above-mentioned drawbacks of the conventional method, and contains the following components (a) and (b) as essential components, and the weight ratio of component (a) / component (b) is 98/2 ~
Add 99.99 / 0.01 cement dispersant to the kneading water, or at the same time or within 5 minutes when the kneading water is added,
The present invention provides a ready-mixed concrete composition having a slump loss of 18 to 24 cm immediately after kneading, which is obtained by adding 0.15 to 0.5% by weight based on the weight of cement and has a small slump loss.

(A) A polycarboxylic acid-based cement dispersant which is a polyacrylic acid or polymethacrylic acid, or a polymer of acrylic acid or methacrylic acid and another polymerizable monomer or a salt thereof, and has an average molecular weight of 1,000 to 10,000.

(B) Defoaming agent.

The present inventors have discovered that the component (a) of the present invention has extremely low separability of concrete when added in excess, as compared with general cement dispersants. Further, as described above, since the component (a) has a relatively small slump loss, it has been found that the slump can be retained for a long time by adding excessively. However, with each of these components (a), a remarkable increase in the amount of air was observed with an increase in the amount added, and as a result, if only the component (a) is excessively added, the strength of the concrete decreases significantly.

The component (b) of the present invention compensates for the disadvantage of excessive addition of the component (a), and the weight ratio of the component (a) and the component (b) is
By adding the mixture of 98/2 to 99.99 / 0.01 to the kneading water, or by adding 0.15 to 0.5% by weight to the cement weight at the same time or within 5 minutes when the kneading water is added. The ready-mixed concrete composition of the present invention is obtained.

A technique for adding such a mixture of a cement dispersant and an antifoaming agent to a cement mixture slurry is described in Japanese Patent Publication No. 57-2669, which discloses resistance to separation of concrete which is the object of the present invention. It does not discuss the properties and prevention of slump loss, but merely aims to increase the strength by decreasing the water content. Further, the disclosed cement dispersant is a naphthalenesulfonic acid formalin condensate, which is different from the specific polycarboxylic acid cement dispersant invented by the present inventors.

The cement dispersant of the present invention can be used as an acid, but it is generally preferable to use it in the form of a salt. Examples of the cation to be formed include Li, Na, K, Ca, Mg, NH ₄ , alkanalamine, N-alkyl-substituted polyamine, ethylenediamine, polyethylenepolyamine, polyethyleneimine, and their alkylene oxide adducts.

Examples of the component (a) of the present invention include the following.

Polyacrylic acid or polymethacrylic acid, or a polymer of acrylic acid or methacrylic acid and another polymerizable monomer, or a salt thereof.

The other polymerizable monomer is an acrylic acid ester or a methacrylic acid ester which may have a functional group, and specifically includes an alkyl group having 1 to 8 carbon atoms, a hydroxyethyl group, a polyoxyethylene group, a polyoxyethylene group, and a polyoxyethylene group. Examples thereof include acrylic acid esters or methacrylic acid esters such as oxyalkylene groups. Of course, mixtures of these are also used. In this case, it is preferable that acrylic acid or methacrylic acid accounts for 30% by weight or more of all the monomers.

The component (a) of the present invention has an average molecular weight of 1,000 to 10,000, preferably 3,000 to 8,000. The molecular weight of the component (a) of the present invention is a value determined by gel permeation chromatography using polyacrylic acid as a reference substance.

Examples of the component (b) of the present invention include the following.

Mineral oil type: Kerosene, liquid paraffin Oil / fat type: Animal / vegetable oil, sesame oil, castor oil, alkylene oxide adducts thereof Fatty acid type: Oleic acid, stearic acid, alkylene oxide adducts thereof Fatty acid ester type: Diethylene glycol laurate, glycerin monoricinoleate , Alkenylsuccinic acid derivative, sorbitol monolaurate, sorbitol trioleate, polyoxyethylene monolaurate, polyoxyethylene sorbitol monolaurate, natural wax Alcohol system: octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols, polyoxy Alkylene glycol amide type: polyoxyalkylene amide, acrylate polyamine Phosphate type: tributyl phosphate, sodium octylphos Metal soap type: Aluminum stearate, Calcium oleate Silicone type: Dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane, fluorosilicone oil Among these, the fat and oil type and the fatty acid ester type are the remaining bubble diameters. Is small and preferable. Silicone type is (b)
It is effective when reducing the ratio of the components.

The addition amount of the cement dispersant of the present invention is 0.15 to 0.5% by weight with respect to the weight of cement, and if it exceeds 0.5% by weight, not only is it disadvantageous over time, but it also causes a delay in curing and an increase in breathing water. Absent. Further, if it is less than 0.15% by weight, slump loss is remarkable, and even if it is added at the ready-mixed concrete factory, the workability deteriorates before the arrival at the actual pouring site.

It is important to add these cement dispersants to the kneading water at the same time as the kneading water is added, or within 5 minutes, so that it can be easily added at the ready-mixed concrete plant. Thus, a ready-mixed concrete composition having a well-established quality is obtained in a well-controlled state.

In the present invention, a cement additive (material) other than the above-mentioned components (a) and (b), for example, a cement dispersant, AE
Water-reducing agent, superplasticizer, high-performance water-reducing agent, (super) retarder, early-strengthening agent, accelerator, water-retaining agent, thickener, self-leveling agent, waterproofing agent, rust preventive, coloring agent, anti-fu (Mold) agent, crack reducing agent, polymer emulsion, other surfactant, water-soluble polymer, expanding agent (material), glass fiber, fly ash, cinder ash, clinker ash, husk ash, blast furnace slag, silica fume, A combination with silica powder or the like is also possible.

As these cement additives (materials), Takakazu Maruyasu and Shunichi Mizuno “Concrete Engineering”, Corona Publishing Co., Ltd., 1982 edition, Yamada Sequential Edition “Knowledge of Cement Concrete”,
Publicly known are those described in the Economic Research Institute, 1983 edition, or Kenichi Hattori, Toshihiro Higashi, "New Surfactant Comprehensive Material Collection", Management Development Center Publishing, pages 941-958, etc. ing.

An example is as follows.

Cement dispersant: As a cement dispersant other than the cement dispersant according to the present invention, Naphthalene sulfonic acid formalin condensate salt, lignin sulfonate, melamine sulfonic acid formalin, which is a trade name of Mighty 150 "Kao Soap Co., Ltd." There are condensate salts, polycarboxylic acid salts and the like, and among these, naphthalene sulfonic acid formalin condensate salts and lignin sulfonic acid salts are particularly suitable. As the naphthalene sulfonic acid referred to in the present invention, naphthalene sulfonic acid and alkylnaphthalene sulfonic acid and their condensates, creosote oil containing these components, naphthalene oil, components such as pitch generated in the process of coking of coal Alternatively, a sulfonated product such as coal liquefied oil is also used. Further, a compound which is not partially sulfonated may be contained as naphthalene sulfonic acid or alkylnaphthalene sulfonic acid. Therefore, the naphthalenesulfonic acid formalin condensate may be a condensate or a mixture of condensates, or may be a cocondensate of two or more kinds. Of course, it may be a cocondensation product of the naphthalenesulfonic acid referred to in the present invention and another cocondensable compound such as ligninsulfonic acid.

As a lignin sulfonate, Chemical Admixture f
or Concrete (MRRIXOM, E & F.N.Spon Ltd) pages 5 to 9 are good analytical values and pure lignosulphonate with properties close to the molecular weight distribution.

AE agents; resin soap, saturated or unsaturated fatty acids, sodium hydroxystearate, lauryl sulfate, ABS, LA
S, alkane sulfonate, polyoxyethylene alkyl ether, alkyl ether sulfonate or phosphate, lignin sulfonate, protein material, alkenyl sulfosuccinic acid, α-olefin sulfonate and the like.

AE water reducing agent, high-performance water reducing agent, superplasticizer; polyol complex, oxycarboxylic acid salt, polycarboxylic acid, lignin sulfonate, melamine sulfonic acid formalin condensate, creosote oil sulfonic acid formalin condensate, naphthalene sulfonic acid Formalin condensate, polyoxyethylene alkyl aryl ether type, etc.

(Super) retarder; lignin sulfonate, oxycarboxylate, magnesium fluorosilicate, phosphoric acid and its salts or boric acid esters, aminocarboxylic acids and their salts, alkali-soluble proteins, polyacrylic acid compounds, Humic acid, tannic acid,
Polyhydric alcohols such as phenol and glycerin.

Early strengthening agents / accelerators; chlorides such as calcium chloride, iron chloride and magnesium chloride, sulfates, potassium hydroxide, sodium hydroxide, carbonates, thiosulfates, formic acid and formates, alkanolamines and alumina cement.

Waterproofing agent: fatty acid (salt), fatty acid ester, oil and fat, silicone, paraffin, asphalt, wax and the like.

Anticorrosion agent: nitrite, phosphate, zinc oxide, etc.

Crack reducing agent; Polyoxyalkyl ether polymer emulsion; Other surfactants; Anion, cation, nonion and amphoteric surfactant Water-soluble polymer; Cellulose derivatives such as carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinyl alcohol , Starch, starch phosphate, sodium alginate, gelatin, sodium polyacrylate, polyacrylamide, polyoxyethylene or polyoxypropylene polymers or copolymers thereof, acrylic acid copolymers having amino groups in the molecule and quaternary thereof Compounds, etc.

Expansive material; ettringite type, coal type, etc.

The order of addition of the cement additive (material) and the cement dispersant of the present invention is not particularly limited, and for example, the additive (material) may be added after the dispersant of the present invention is added, or It is also possible to add the dispersant of the present invention after adding the above-mentioned additive (material), and there are addition methods such as simultaneously adding the above-mentioned additive (material) and the present dispersant of the present invention.

Examples of materials used for the hydraulic cement compound that can be used in the present invention are as follows.

Cement; Portland cement, blast furnace cement, fly ash cement, silica cement, silica fume blended cement, alumina cement, expanded cement, colloidal cement, white cement, oil well cement Aggregate: river sand (land), land sand (land), sea sand (Ri), crushed sand (Ri), slag sand (Ri), artificial (light) sand (Ri), natural lightweight aggregate The composition (formulation) of the hydraulic cement compound that can be used in the present invention is "concrete" published by Asakura Shoten. Engineering Handbook ",
The formulations described in "Concrete Handbook" published by Gihodo can be used.

[Action]

The mechanism for preventing the reduction of workability in the cement composition according to the present invention is considered as follows.

That is, cement, water, sand, cement particles in the cement mixture formed by kneading gravel and an admixture, after kneading, chemical agglomeration due to hydration reaction and physical agglomeration due to interparticle attractive force proceeds, Liquidity is gradually lost. In the present invention, by adding a large amount of the component (a), a large charge is imparted to the cement particles, a repulsive force is generated between the particles, the aggregation between the cement particles is prevented, and the slump loss is made extremely small. Further, due to the combined effect of the components (a) and (b), bubbles having a large particle size are selectively defoamed, thereby providing good workability.

〔The invention's effect〕

Since it has become possible to maintain the workability of the ready-mixed concrete composition for a long time according to the present invention, a good ready-mixed concrete composition is produced in the ready-mixed concrete factory, and the cement dispersant is re-added at the casting site. Since it is not necessary, it has become possible to save various troubles and costs.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 3 and Comparative Examples 1 to 2 Using a dispersant in which the component (a) shown in Table 2 and the component (b) shown in Table 3 are compounded as shown in Table 4, the workability of concrete is maintained. An experiment was conducted on the effect. The following materials were used as concrete, and the mixing ratio shown in Table 1 was used. Workability is measured according to JIS A 1101 slump test.
According to JIS A 1128 air volume test. Also, the compressive strength test
According to JIS A 1108.

The experimental conditions are shown in Table 4, and the test results are shown in Tables 5 and 6.

Materials used Cement (C): Ordinary Portland cement (specific gravity 3.1
7) Fine aggregate (S): From Kinokawa (specific gravity 2.57) Coarse aggregate (G): From Hidakagawa (specific gravity 2.59) Water (W) Concrete mixing method Dissolve cement dispersant in water in advance. At 25 ℃
50 concretes were kneaded for 2 minutes using 100 tilting mixers, and then slump was measured at a predetermined time while stirring at a low speed of 4 rpm.

Compounding (A) component (B) component Experimental conditions Test results As is clear from the above results, it is clear that the concrete composition of the present invention has an extremely excellent effect in terms of the amount of entrained air and the slump residual rate.

Claims (3)

[Claims] 1. The following components (a) and (b) are contained as essential components, and the weight ratio of component (a) / component (b) is 98.
A cement dispersant of / 2 to 99.99 / 0.01 is added to the kneading water, or 0.15 to 0.5 wt% of the cement weight is added at the same time or within 5 minutes when the kneading water is added. The resulting ready-mixed concrete composition having a slump of 18 to 24 cm immediately after kneading and having little slump loss. (A) Polyacrylic acid or polymethacrylic acid, or a polycarboxylic acid-based cement dispersant having an average molecular weight of 1,000 to 10,000, which is a polymer of acrylic acid or methacrylic acid and another polymerizable monomer or a salt thereof. ) Defoamer. 2. The ready-mixed concrete composition according to claim 1, wherein the other polymerizable monomer is an acrylic acid ester or a methacrylic acid ester which may have a functional group. 3. An antifoaming agent of component (b) is an oil or fat type, a fatty acid type,
The ready-mixed concrete composition according to claim 1 or 2, which is selected from one or more fatty acid ester-based compounds.