JP2019112250A - Admixture for low quality fine aggregate-containing concrete and cement composition containing the same - Google Patents

Abstract

To provide an admixture exhibiting excellent flowability, and further capable of suppressing increase of viscosity and reduction of state with the lapse of time, even when used for concrete containing low quality fine aggregate, and a cement composition containing the same.SOLUTION: There is provided an admixture for low quality fine aggregate-containing concrete containing a polycondensated article having following (I) to (III): (I) at least one structural unit, which is an aromatic part having a polyether side chain having 9 to 41 ethylene glycol units, (II) at least one structural unit, which is an aromatic part having at least one phosphoric acid ester group, and (III) at least one methylene unit (-CH-), and having mass average molecular weight Mw of the polycondensated article in a range of 3,000 to 50,000.SELECTED DRAWING: None

Description

  The present invention relates to admixtures for use in concrete containing low quality fine aggregate as fine aggregate, in particular to chemical admixtures for concrete. The invention also relates to a cement composition comprising such an admixture.

  In recent years, due to the exhaustion of fine aggregate resources, not only naturally produced river sands and mountain sands, but also crushed sand obtained by breaking up rocks and adjusting the particle size, and slag removed from blast furnaces called slag fine aggregates Water-quenched slag, etc., which has been rapidly cooled and subjected to particle size adjustment and anti-caking treatment, are used for concrete.

  Such artificially produced fine aggregate generally has better freshness due to the difference in the particle shape and the fine particle content compared to the rounded and rounded natural fine aggregate. It is said that it is difficult to obtain the concrete shown. For example, angular grain shape and low water holding capacity tend to cause problems such as increase in unit water volume and increase in bleeding, and the state of concrete (fresh concrete has appropriate viscosity, and materials do not separate and come together Is said to be inferior to the flowing nature, which may be simply referred to as "state".

  The condition of concrete not only affects slump and filling property at the time of construction but also relates to bleeding and separation of coarse aggregate, and also pumping loss and pressure dewatering at the time of pumping, so new requirements for concrete are required. It is one of the required performances. Although the evaluation method has not yet been established, in general, visual observation, slump shape, deformability index (slump, flow), viscosity index (viscometer indicated value, funnel drop time) etc. are comprehensively It is often judged.

  Further, in recent years, in concrete placing, a technique for pumping concrete by pump has widely spread, and there is a case where even if fresh concrete arrives at a site, it is further pumped and placed. When pumping concrete with a pump, changes in properties such as pumping loss and pressure dehydration are likely to occur. Therefore, there is a demand for a cohesive concrete that is excellent not only in fluidity but also in material separation resistance, ie, concrete having excellent fluidity and good viscosity.

  On the other hand, various additives are used as well as properly adjusting the composition of the concrete material. For example, use of a workability improver having a specific chemical structure (Patent Document 1), and further, use of a saccharide or a polycarboxylate-based dispersant having a specific structure (Patent Document 2) is known. However, with these modifiers and dispersants, the action of appropriate viscosity application is not sufficient, and the viscosity tends to increase with the elapsed time, and in particular, it is difficult to maintain the state of concrete with the elapsed time Met.

JP 2003-165755 Unexamined-Japanese-Patent No. 2003-2714

  The present invention is an admixture capable of exhibiting excellent fluidity even when used in concrete containing low-quality fine aggregate, and further capable of suppressing increase in viscosity and decrease in condition with elapsed time. It is an object of the present invention to provide a cement composition containing the same.

  As a result of repeated studies to solve the above problems, the present inventors have used an admixture containing a polycondensate having a specific structural unit to concrete containing a low quality fine aggregate. It has been found that it is possible to obtain an admixture capable of imparting excellent fluidity and further suppressing increase in viscosity and decrease in condition with elapsed time, and a cement composition containing the same.

That is, the gist configuration of the present invention is as follows.
[1] A polycondensate having at least one structural unit (I), at least one structural unit (II), and at least one structural unit (III),
The structural unit (I) is an aromatic moiety having a polyether side chain having an alkylene glycol unit, provided that the number of ethylene glycol units in the polyether side chain is 9 to 41, and the ethylene glycol unit The content of units is more than 80 mol% with respect to all the alkylene glycol units in the polyether side chain,
The structural unit (II) is an aromatic moiety having at least one phosphate group and / or a salt thereof, provided that the value of the molar ratio of the structural unit (I) to the structural unit (II) is , 0.3-4,
The structural unit (III) is at least one methylene unit (—CH ₂ —), and the methylene unit is bonded to two aromatic structural units, the structural unit (I) and the structural unit (II) Wherein said aromatic structural units are, independently of one another, identical or different, and
Admixture for low-quality fine aggregate-containing concrete, wherein the mass average molecular weight Mw of the polycondensate containing the structural units (I), (II) and (III) is in the range of 3,000 to 50,000. .
[2] The polycondensate further has at least one structural unit (IV),
The structural unit (IV) is represented by an aromatic structural unit different from the structural unit (I) and the structural unit (II),
The methylene unit is bonded to the three aromatic structural units of the structural unit (I), the structural unit (II) and the structural unit (IV), wherein the aromatic structural units are independent of each other Identical or different, and
The weight average molecular weight Mw of the polycondensate containing the structural units (I), (II), (III) and (IV) is in the range of 3,000 to 50,000 as described in the above [1]. Admixture.
[3] The admixture according to the above [1] or [2], further comprising a retention aid.
[4] The above-mentioned [3], wherein the holding assistant is a copolymer obtained by polymerizing a hydrolyzable monomer, an ethylenically unsaturated monomer containing a polyoxyalkylene group, and a cement-adsorbable monomer. Admixture as described in.
[5] The above-mentioned [4], wherein the retention aid does not contain a cement-adsorbable monomer, and is a copolymer formed by polymerizing a hydrolyzable monomer and an ethylenically unsaturated monomer containing a polyoxyalkylene group. The admixture as described in 3].
[6] A cement composition containing the admixture according to any one of the above [1] to [5].

  By using the admixture according to the present invention in concrete containing low-quality fine aggregate, it imparts excellent fluidity, and further prevents increase in viscosity and deterioration of the state with the passage of time. Can. Therefore, it becomes possible to bring about improvement of pumpability, such as pumping loss and pressure dehydration, and suppression of bleeding.

  Hereinafter, embodiments of the present invention will be described in detail. In the following, the numerical range represented using “to” means a range including the numerical values described before and after “to” as the lower limit value and the upper limit value.

(Low quality fine aggregate containing concrete)
In the present invention, low-quality fine aggregate-containing concrete means concrete in which low-quality fine aggregate is contained as a fine aggregate in cement. In addition, low-quality fine aggregate does not have a rounded particle shape like natural fine aggregate, resulting in an increase in unit water volume when used for concrete, resulting in increased bleeding. Mean fine aggregate. As such low-quality fine aggregate, for example, crushed sand produced by crushing rock, slag fine aggregate obtained by quenching slag extracted from blast furnace with water is preferable, specifically, the standard of JIS A 5005 Crushed sand conforming to the above, or slag aggregate (slag fine aggregate) conforming to the standard of JIS A 5011 is more preferable. Among these fine aggregates, a fine aggregate in which the particle shape determination real volume defined in JIS A 5005 exhibits around the lower limit (54%) is preferable. More specifically, a fine aggregate showing a particle shape determination real percentage of 50% to 58% is preferable, and a fine aggregate showing 52% to 56% is more preferable. The content of the low quality fine aggregate contained in the concrete is not particularly limited, but in the cement composition, 400 to 1,200 kg / m ³ is preferable, and 800 to 1,000 kg / m ^3. Is more preferred.

[Admixture]
The admixture according to the present invention is a low-quality fine aggregate-containing admixture for concrete, which comprises at least one structural unit (I), at least one structural unit (II) and at least one structural unit (III) And a polycondensate having
Structural unit (I) is an aromatic moiety having a polyether side chain having an alkylene glycol unit, provided that the number of ethylene glycol units in the polyether side chain is 9 to 41, and The content is more than 80 mol%, relative to all alkylene glycol units in the polyether side chain,
Structural unit (II) is an aromatic moiety having at least one phosphate group and / or a salt thereof, provided that the molar ratio of structural unit (I) to structural unit (II) is 0. 0. 3-4,
Structural unit (III) is at least one methylene unit (-CH _2- ), and the methylene unit is bonded to two aromatic structural units Y of the structural unit (I) and the structural unit (II) Wherein the aromatic structural units Y are, independently of one another, identical or different and
The mass average molecular weight Mw of the polycondensate containing structural units (I), (II) and (III) is in the range of 3,000 to 50,000.
By using such an admixture in concrete containing low-quality fine aggregate, it is possible to impart excellent fluidity, and to suppress the increase in viscosity and the decrease in state with the passage of time. . Therefore, it becomes possible to bring about improvement of pumpability, such as pumping loss and pressure dehydration, and suppression of bleeding.

<Structural unit (I)>
Structural unit (I) has proven to be advantageous to have a minimum polyether side chain length in order to obtain a reasonable dispersing action in cement binder systems, in particular in concrete. Very short chains are not preferred economically. This is because the dispersibility of the admixture is low and the feed amount required to obtain the dispersing action is increased, while, if the polyether side chain of the polycondensate is too long, such admixture is caused. Rheological properties of the concrete made with the agent (high viscosity). The content of ethylene glycol units in the polyether side chain is preferably more than 80 mol% with respect to all the alkylene glycol units in the polyether side chain, in order to make the polycondensate product sufficiently soluble. It is more preferably more than 85 mol%, still more preferably more than 90 mol%, and most preferably more than 95 mol%.

  The aromatic moiety in structural unit (I) has one or more polyether side chains, preferably one polyether side chain. The structural units (I) are, independently of one another, identical or different. This means that one or more of the structural units (I) can be present in the polycondensate. The structural units (I) can differ, for example, in the type of polyether side chains, in the type of aromatic structures.

  The structural unit (I) is derived from the respective aromatic monomer, which is an aromatic monomer having a polyether side chain containing an alkylene glycol unit, the side chain length and the proportion of ethylene glycol in the side chain Meet the above requirements for This monomer is incorporated into the polycondensation product by the formaldehyde of the monomer and the monomer that becomes the structural unit (I) when being incorporated into the polycondensation product by the polycondensation reaction. In particular, structural unit (I) is an aromatic monomer derived from the absence of the two hydrogen atoms (formed with one oxygen atom from formaldehyde) which are abstracted from the monomer during the polycondensation reaction It is different from

The aromatic moiety in structural unit (I) is preferably a substituted or unsubstituted aromatic moiety having a polyether side chain according to the present invention, the aromatic being a benzene ring or a naphthalene ring May be One or more polyether side chains, preferably one or two polyether side chains, most preferably one polyether side chain may be present in structural unit (I). In this context "substituted aromatic moiety" preferably denotes any substituent other than a polyether side chain or other than a polyether side chain according to the invention. The substituent is preferably a C ₁ -C ₁₀ alkyl group, most preferably a methyl group. The aromatic moiety preferably has 5 to 10 carbon atoms, more preferably 5 to 6 carbon atoms in the aromatic structure, and most preferably the aromatic structural unit has 6 carbon atoms, Benzene or substituted derivatives of benzene. The aromatic moiety in the structural unit (I) may be a heteroaromatic structure containing an atom different from carbon, such as oxygen (in furfuryl alcohol), but an atom of the aromatic ring structure is It is preferably a carbon atom.

  The number of ethylene glycol units in the polyether side chain of the structural unit (I) is 9 to 41, preferably 9 to 35, more preferably 12 to 23. The relatively short polyether side chain length contributes to the good rheological properties of the concrete made with the admixture according to the invention comprising the polycondensate having the structural unit (I), in particular obtaining a low plastic viscosity Be On the other hand, polyether side chain lengths which are too short are not economically desirable because the dispersing action is reduced and the amount of supply required to obtain a certain level of workability (e.g. slump in concrete tests) is increased.

  The structural unit (I) may have a relatively long hydrophilic polyether side chain. Thereby, steric repulsion can be provided between the polycondensates adsorbed on the surface of the cement particles, and as a result, the dispersing action can be improved.

  Structural unit (I) can be derived from the following monomers, but is not limited thereto. For example, ethoxylated derivatives of aromatic alcohols or amines are preferred, phenol, cresol, resorcinol, catechol, hydroquinone, naphthol, furfuryl alcohol or ethoxylated derivatives of aniline are more preferred, ethoxylated phenols in particular preferable. Preferably, resorcinol, catechol and hydroquinone have two polyether side chains. Resorcinol, catechol and hydroquinone can in each case have only one polyether side chain. In each case, less than 20 mol% of alkylene glycol units are contained, which are not ethylene glycol units.

（式（Ｉａ）中、
Ａは、同一であるか、又は異なり、炭素原子を５〜１０個有する、置換若しくは非置換の芳香族又は複素環式芳香族化合物によって表され、
Ｂは、同一であるか、又は異なり、Ｎ、ＮＨ、又はＯであり、その際、ＢがＮであれば、ｎは２であり、ＢがＮＨ又はＯであれば、ｎは１であり、
Ｒ¹及びＲ²は、相互に独立して、同一であるか又は異なり、分枝鎖状若しくは直鎖状のＣ₁〜Ｃ₁₀アルキル基、Ｃ₅〜Ｃ₈シクロアルキル基、アリール基、ヘテロアリール基又はＨであり、ただし、ポリエーテル側鎖におけるエチレングリコール単位（Ｒ¹及びＲ²がＨである）の数は、９〜４１であり、エチレングリコール単位の含分は、ポリエーテル側鎖中の全てのアルキレングリコールに対して８０ｍｏｌ％超であり、
ａは、同一であるか、又は異なり、１２〜５０の整数であり、かつ
Ｘは、同一であるか、又は異なり、直鎖状若しくは分枝鎖状のＣ₁〜Ｃ₁₀アルキル基、Ｃ₅〜Ｃ₈シクロアルキル基、アリール基、ヘテロアリール基、又はＨである）によって表される。上記式（Ｉａ）において、基「Ａ」が後述する構造単位（ＩＩＩ）のメチレン単位と結合することより、本発明における混和剤の主成分となる重縮合物が形成される。 The structural unit (I) preferably has the following general formula (Ia):

(In formula (Ia),
A is the same or different and is represented by a substituted or unsubstituted aromatic or heteroaromatic compound having 5 to 10 carbon atoms,
B is the same or different and is N, NH or O, in which case if B is N then n is 2 and if B is NH or O then n is 1 ,
R ¹ and R ² are, independently of one another, identical or different, branched or linear C _{1 to} C ₁₀ alkyl group, C _{5 to} C ₈ cycloalkyl group, aryl group, hetero Aryl group or H, provided that the number of ethylene glycol units in the polyether side chain (R ¹ and R ² are H) is 9 to 41, and the proportion of ethylene glycol units is the polyether side chain More than 80 mol%, relative to all alkylene glycols in
a is the same or different, is an integer of 12 to 50, and X is the same or different, and a linear or branched C _{1 to} C ₁₀ alkyl group, C ₅ -C ₈ cycloalkyl group, an aryl group, represented by a heteroaryl group, or H). In the above-mentioned formula (Ia), a polycondensate which is a main component of the admixture in the present invention is formed by bonding the group “A” to a methylene unit of the structural unit (III) described later.

  In formula (Ia), A preferably has 5 to 10 carbon atoms in the aromatic structure, more preferably 5 to 6 carbon atoms, and most preferably 6 carbon atoms in the aromatic structure. And substituted derivatives of benzene or benzene.

  In formula (Ia), B is preferably O (oxygen).

In formula (Ia), R ¹ and R ² are preferably H, methyl, ethyl or phenyl, more preferably H or methyl, particularly preferably H.

  In formula (Ia), a is preferably an integer of 9 to 35.

  In formula (Ia), X is preferably H.

  The structural unit (I) is preferably derived from an alkoxylated aromatic alcohol monomer having a hydroxy group at the end of the polyether side chain, and in particular, a polycondensate of phenyl polyalkylene glycol preferable. Phenyl polyalkylene glycols can be obtained relatively easily, are also economically viable, and the reactivity of aromatic compounds is also relatively good.

The structural unit (I) is preferably derived from a phenylpolyalkylene glycol represented by the following general formula (V):
^{_{- [C 6 H 3 -O- (}} Z 1 O) p -H] - (V)

In formula (V), p is an integer of 9 to 41, preferably an integer of 9 to 35, more preferably an integer of 12 to 23, and Z ¹ is 2 to 5 carbon atoms, preferably 2 to 2 Alkylene having 3 carbon atoms, provided that the proportion of ethylene glycol units (Z ¹ = ethylene) is 80 mol% relative to all alkylene glycol units in the polyether side chain (Z ¹ O) _n More than, preferably more than 85 mol%, more preferably more than 90 mol%, most preferably more than 95 mol%. In Formula (V) above, the aromatic structural moiety of “C ₆ H ₃ ” is bonded to a methylene unit of Structural Unit (III) described later.

The substitution pattern in the aromatic benzene unit (C ₆ H ₃ in the above formula (V)) is the position (1 position) of the oxygen atom bonded to the benzene ring by the activation action (electron donating action) of the oxygen atom bonded to the benzene ring. Are mainly ortho substitution position (2 position) and para substitution position (4 position).

<Structural unit (II)>
The structural unit (II) brings an anionic group to the polycondensate (from phosphoric acid ester to its acid or salt form), which is the positive charge present on the surface of cement particles in the aqueous cement dispersion. Interfere with and are strongly alkaline. Due to electrostatic attraction, the polycondensate adsorbs to the surface of the cement particles and the cement particles are dispersed. Here, the term "phosphate" preferably includes phosphate monoester (PO (OH) ₂ (OR) ₁ ), phosphate diester (PO (OH) (OR) ₂ ), and / or phosphorus. A mixture of acid triesters (PO (OR) ₃ ) is included. The group R in the phosphoric acid ester defines each alcohol having no OH group after the ester reaction, which reacts to form an ester with phosphoric acid. The group R preferably has an aromatic moiety. Monoesters are usually the main products of the phosphorylation reaction.

  The term "phosphorylated monomer" refers to the reaction product of an aromatic alcohol with phosphoric acid, polyphosphoric acid or phosphorous oxide, and the reaction of an aromatic alcohol with a mixture of phosphoric acid, polyphosphoric acid and phosphorous oxide The product is included.

  The proportion of phosphoric monoesters is preferably more than 50% by weight, based on the sum of all phosphoric esters. The content of structural units (II) derived from phosphoric monoesters is preferably more than 50% by weight, based on the sum of all structural units (II).

  In the structural unit (II), the aromatic moiety preferably contains one phosphoric ester group and / or a salt thereof. This means that the use of aromatic monoalcohols is preferred. The structural unit (II) may have more than one and preferably two phosphate ester groups and / or salts thereof. In this case, at least one aromatic dialcohol or aromatic polyalcohol is used. The structural units (II) are, independently of one another, identical or different. This means that one or more of the structural units (II) can be present in the polycondensate.

  Structural unit (II) in the polycondensate is an aromatic moiety having at least one phosphate ester group and / or a salt thereof, provided that the value of molar ratio of structural unit (I) to structural unit (II) Is 0.3 to 4, preferably 0.4 to 3.5, more preferably 0.45 to 3, and most preferably 0.45 to 2.5. The range of this molar ratio is sufficient initial dispersibility of polycondensate (relatively high content of structural unit (II)), and sufficient slump retention property (relatively high content of structural unit (I)) It is advantageous because it can be achieved in concrete samples.

  As described for structural unit (I) above, structural unit (II) is also an aromatic monomer derived from the absence of the two hydrogen atoms withdrawn from the monomer during the polycondensation reaction It is different.

  The aromatic moiety in the structural unit (II) is preferably a substituted or unsubstituted aromatic moiety having at least one phosphate ester group and / or a salt thereof, and the aromatic is a benzene ring even if it is a benzene ring It may be a ring. One or more phosphate groups and / or salts thereof being present in the structural unit (II), preferably one or two phosphate groups and / or salts thereof being present, most preferably One phosphate ester group and / or a salt thereof may be present. The aromatic moiety of structural unit (II) preferably has 5 to 10 carbon atoms, more preferably 5 to 6 carbon atoms in the aromatic structure, and most preferably the aromatic structural unit is It is a substituted benzene or benzene having 6 carbon atoms. The aromatic moiety in the structural unit (II) may be a heteroaromatic structure containing an atom different from carbon, such as oxygen (in furfuryl alcohol), but the atom in the aromatic ring structure is a carbon atom Is preferred.

  The structural unit (II) is preferably derived from an aromatic alcohol monomer. The aromatic alcohol monomer is alkoxylated in the first step, and the obtained alkoxylated aromatic alcohol monomer having a hydroxyl group at the end of the polyether side chain is phosphorylated in the second step, Form a phosphate ester group.

  The structural units (II) derived from the respective phosphorylated aromatic alcohol monomers are different from those described above due to the abstraction of two hydrogen atoms from each monomer. Such structural units (II) are derived from, for example, the following compounds, but are not limited thereto. For example, a phosphorylated product of an aromatic alcohol or a phosphorylated product of hydroquinone is preferable, and phenoxyethanol phosphate (aromatic alcohol: phenoxyethanol), phenoxydiglycol phosphate (aromatic alcohol: phenoxydiglycol), (methoxyphenoxy) ethanol phosphate (Aromatic alcohol: (methoxyphenoxy) ethanol), methyl phenoxy ethanol phosphate (aromatic alcohol: methyl phenoxy ethanol), nonylphenol phosphate (aromatic alcohol; nonylphenol), bis (β-hydroxyethyl) hydroquinone ether phosphate (hydroquinone: bis (β -Hydroxyethyl) hydroquinone ether), bis (β-hydroxyethyl) hydroquinone agent Rujihosufeto (hydroquinone bis (beta-hydroxyethyl) hydroquinone ether) are more preferable, phenoxyethanol phosphate, phenoxy Siji glycol phosphate, bis (beta-hydroxyethyl) hydroquinone ether diphosphate is particularly preferred, and most preferably phenoxyethanol phosphate. Mixtures of the above mentioned monomers from which the structural unit (II) is derived may be used.

Usually, the main product (monoester of phosphoric acid and one equivalent of aromatic alcohol: PO.sub. (OH) during phosphorylation reaction (e.g. reaction of the above aromatic alcohol containing hydroquinone with phosphoric acid) It should be noted that, besides ₂ (OR) ₁ )), by-products are also formed. The by-products are, in particular, diesters of phosphoric acid and 2 equivalents of aromatic alcohol (PO (OH) (OR) ₂ ) or triesters of phosphoric acid and 3 equivalents of aromatic alcohol (PO (OR) ₃ ) The formation of triesters is not usually produced as temperatures above 150 ° C. are required. Here, the group R in the phosphoric acid ester is an aromatic alcohol structure having no OH group after the ester reaction. Unreacted alcohol may be present to some extent in the reaction mixture. The proportion is usually less than 35% by weight, preferably less than 5% by weight, of the aromatic alcohol used. The main product (monoester) after the phosphorylation reaction is usually present in the reaction mixture at a level of more than 50% by weight, preferably more than 65% by weight, based on the aromatic alcohol used.

（式（ＩＩａ）中、
Ｄは、同一であるか、又は異なり、炭素原子を５〜１０個有する、置換若しくは非置換の芳香族又は複素環式芳香族化合物によって表され、
Ｅは、同一であるか、又は異なり、Ｎ、ＮＨ、又はＯであり、ＥがＮであれば、ｍは２であり、ＥがＮＨ又はＯであれば、ｍは１であり、
Ｒ³及びＲ⁴は、相互に独立して、同一であるか、又は異なり、直鎖状若しくは分枝鎖状のＣ₁〜Ｃ₁₀アルキル基、Ｃ₅〜Ｃ₈シクロアルキル基、アリール基、ヘテロアリール基又はＨであり、
ｂは、同一であるか、又は異なり、０〜１０の整数であり、かつ
Ｍａは、相互に独立して、同一であるか、又は異なり、Ｈ又はカチオン等価物である）で表される。上記式（ＩＩａ）において、基「Ｄ」が後述する構造単位（ＩＩＩ）のメチレン単位と結合することより、本発明における混和剤の主成分となる重縮合物が形成される。 The structural unit (II) preferably has the following general formula (IIa):

(In the formula (IIa),
D is the same or different and is represented by a substituted or unsubstituted aromatic or heteroaromatic compound having 5 to 10 carbon atoms,
E is the same or different and is N, NH or O, and when E is N, m is 2 and when E is NH or O, m is 1.
R ³ and R ⁴ are, independently of one another, identical or different, and linear or branched C _{1 to} C ₁₀ alkyl group, C _{5 to} C ₈ cycloalkyl group, aryl group, Heteroaryl or H,
b is the same or different, is an integer of 0 to 10, and Ma is mutually independently, the same or different, and is represented by H or a cation equivalent. In the above formula (IIa), a polycondensate which is a main component of the admixture in the present invention is formed by bonding the group "D" to a methylene unit of the structural unit (III) described later.

  In formula (IIa), D preferably has 5 to 10 carbon atoms in the aromatic structure, more preferably 5 to 6 carbon atoms in the aromatic structure, most preferably in the aromatic structure It is a substituted benzene or benzene having 6 carbon atoms.

  In formula (IIa), E is preferably O (oxygen).

In formula (IIa), R ³ and R ⁴ independently of each other are preferably H, methyl, ethyl or phenyl, more preferably H or methyl, particularly preferably H, and most preferably And R ³ and R ⁴ are both H.

  In formula (IIa), b is preferably an integer of 1 to 5, more preferably an integer of 1 to 2, and most preferably 1.

The phosphoric acid ester represented by the formula (IIa) may be an acid having two acidic protons (Ma = H). Phosphoric esters can also be present in deprotonated form, in which case the protons are replaced by cation equivalents. The phosphate ester may be partially deprotonated. The term "cation equivalent" refers to any metal cation or ammonium cation (which can replace a proton) which may be substituted, but the molecule is electrically neutral. M is preferably NH ₄ , an alkali metal or 1⁄2 alkaline earth metal.

  The group A of the structural unit (Ia) and the group D of the structural unit (IIa) are, for example, independently of each other, phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2-methoxyphenyl It is preferably 3-methoxyphenyl or 4-methoxyphenyl, more preferably phenyl. A plurality of structural units (Ia) having different types of groups A may be present in the polycondensate, and a plurality of structural units (IIa) having different types of groups D may also be present in the polycondensates Good. The groups B and E are preferably, independently of one another, O (oxygen).

The structural unit (II) is preferably an alkoxylated phenol phosphate as represented by the following general formula (VI), or an alkoxylated as represented by the following general formula (VII) Derived from hydroquinone phosphate ester:
^{_{- [C 6 H 3 -O- (}} Z 2 O) q -PO 3 M 2] - (VI)
_{- [[M 2 O 3 P-} (Z 3 O) r] -O-C 6 H 2 -O - [(Z 4 O) s -PO 3 M 2]] - (VII)

In any of the formulas (VI) and (VII), q, r and s are an integer of 1 to 5, preferably an integer of 1 to 2, more preferably 1, Z ² , Z ³ and Z ⁴ are And, independently of each other, alkylene having 2 to 5, preferably 2 to 3 carbon atoms, more preferably ethylene. M is, independently of one another, identical or different, H or a cation equivalent. The aromatic structural moiety of “C ₆ H ₃ ” in the above formula (VI) and the aromatic structural moiety of “C ₆ H ₂ ” in the above formula (VII) are methylene of structural unit (III) described later, respectively. Combined into a unit.

The esters of the general formulas (VI) and (VII) may be acids with two acidic protons (M = H). The ester may also be present in deprotonated form, in which case the protons are replaced by cation equivalents. The ester may be partially deprotonated. The term cation equivalent is as described above and M is preferably NH ₄ , an alkali metal, or a 1/2 alkaline earth metal. Thus, for example, in the case of an alkaline earth metal having two positive charges, there must be a factor of 1/2 to guarantee neutrality (1/2 alkali metal), for example a metal When component "M" is Al ³⁺ , 1⁄3 Al is the cation equivalent. In addition, for example, a mixed cation equivalent having two or more types of metal cations may be used.

  Such alkoxylated phenol phosphates or alkoxylated hydroquinone phosphates are relatively easy to obtain and are economically desirable, and also the reactivity of aromatic compounds in the polycondensation reaction It is relatively good.

<Structural unit (III)>
Structural unit (III) is at least one methylene unit (—CH ₂ —), and the methylene unit is bonded to two aromatic structural units, structural unit (I) and structural unit (II) The aromatic structural units are, independently of one another, identical or different and correspond to the above-mentioned aromatic moieties in structural unit (I) and structural unit (II). The methylene units are introduced by the reaction of formaldehyde while forming water during the polycondensation, preferably more than one methylene unit is contained in the polycondensate.

<Structural unit (IV)>
The polycondensate may further have at least one structural unit (IV). Structural unit (IV) is an aromatic structural unit of a polycondensate different from structural unit (I) and structural unit (II), and may be any aromatic structural unit. Further, when the structural unit (IV) is contained, the methylene unit in the structural unit (III) is bonded to three aromatic structural units of the structural unit (I), the structural unit (II) and the structural unit (IV) The aromatic structural units in structural unit (IV) are, independently of one another, identical or different. This means that one or more structural units (IV) can be present in the polycondensate.

  The structural unit (IV) can be derived, for example, from any aromatic monomer capable of reacting with formaldehyde in the polycondensation reaction (two hydrogen atoms are withdrawn from each monomer). Examples of monomers from which the structural unit (IV) is derived include phenoxy alcohol, phenol, naphthol, aniline, benzene-1,2-diol, benzene-1,2,3-triol, 2-hydroxybenzoic acid, 2,3- Dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, phthalic acid, 3-hydroxyphthalic acid, 1,2-dihydroxynaphthalene, and 2,3-dihydroxynaphthalene Not limited to these.

  Structural unit (IV) may also be a structural unit similar to structural unit (I), differing only in the number of ethylene glycol units in the side chains. As such structural unit (IV), preferably, it is an aromatic moiety having a polyether side chain having an alkylene glycol unit, provided that the number of ethylene glycol units in the polyether side chain is 42 to 120, And the content of ethylene glycol units is a structural unit which is more than 80 mol% with respect to all the alkylene glycol units in the polyether side chain.

<Polycondensate>
The polycondensate contained in the admixture according to the present invention is a main component of the admixture, and a polycondensate containing structural units (I), (II) and (III), and a structural unit (I) The mass average molecular weight Mw of the polycondensate containing (II), (III), and (IV) is in the range of 3,000 to 50,000.

  The value of the molar ratio of ethylene glycol units from structural unit (I) to phosphoric acid ester units from structural unit (II) is preferably 11 to 40/1, and more preferably 12 to 35/1. And 13 to 30/1 are more preferable. To identify this molar ratio, the sum of all ethylene glycol units from structural unit (I) is calculated, also taking into account the presence of different types of structural units (I).

  The molar ratio of ethylene glycol units from structural unit (I) to phosphoric acid ester units from structural unit (II) is calculated to be at least 9 and at most 41 in structural unit (I) Alkylene glycol is combined with the value of the molar ratio of 0.3 to 4 of structural unit (I) to structural unit (II), and the minimum value is 9/8 (structural unit (I) / structural unit (II The short side chain of 9EO whose molar ratio value is 4), as well as the possibility that two phosphate groups may be present in structural unit (II)). On the other hand, in combination with 0.3 which is the lower limit value of the molar ratio of structural unit (I) / structural unit (II), the long side chain of 41 EO and the phosphate ester present in structural unit (II) The maximum value is obtained as 136.7 (41 / 0.3). If the molar ratio of ethylene glycol units from structural unit (I) to phosphoric acid ester units from structural unit (II) is lower than the lower limit (9/8), the phosphoric acid ester group is excessive, so a concrete test sample The slump retention at the end is worse. On the other hand, if this molar ratio is larger than the upper limit value (136.7), the adsorptivity to cement particles is too weak, so the water reduction characteristic (initial water reduction rate in the concrete test body) is not very good. Thus, the range of the molar ratio of the ethylene glycol unit from structural unit (I) to the phosphoric acid ester unit from structural unit (II) is in the range of 9/8 to 136.7, thereby giving a concrete test body In the above, an appropriate balance of the two characteristics of the slump retention and the water reduction rate can be obtained, and both the good water reduction rate and the good slump retention can be obtained. Also, the viscosity of the concrete can be lowered.

  The molar ratio of the total of structural units (I) and (II) to structural unit (III) is preferably 0.8 / 1 to 1 / 0.8, more preferably 0.9 / 1 to 1 / 0.9. And most preferably 1/1.

  When structural unit (IV) is further contained in the polycondensate, the molar ratio of the sum of structural unit (I) and structural unit (II) to structural unit (IV) is preferably more than 1/1, More preferably, it is more than 3/1, more preferably more than 5/1.

  Most preferred is a polycondensate in which structural unit (IV) is an aromatic moiety having a polyether side chain containing an alkylene glycol unit, provided that the number of ethylene glycol units in the polyether side chain of structural unit (IV) is Is 42 to 50, and the content of ethylene glycol units is more than 80 mol% with respect to all alkylene glycol units in the polyether side chain of the structural unit (IV).

  The mass average molecular weight Mw of the polycondensate is 3,000 to 50,000, preferably 5,000 to 25,000 g / mol, and more preferably 8,000 to 22,000 g / mol. and most preferably 10,000 g / mol to 19,000 g / mol.

The mass average molecular weight Mw of the polycondensate is the mass average molecular weight of the polycondensate specified by GPC. The combination of columns is OH-Pak SB-G, OH-Pak SB 804 HQ, and OH-Pak SB 802.5 HQ (manufactured by Shodex, Japan), and the eluent is an 80% by volume aqueous solution of HCO ₂ NH ₄ (0.05 mol / l) and 20% by volume of acetonitrile, others, injection volume: 100 μl, flow rate: 0.5 ml / min. Molecular weight calibration is performed with poly (styrene sulfonate) standards for UV detectors and poly (ethylene oxide) standards for RI detectors. Both standards can be purchased from PSS Polymer Standards Service in Germany. UV detection is used at 254 nm to determine the molecular weight of the polymer. UV detectors do not sense inorganic impurities, so they can only sense aromatic compounds.

<Retention aid>
The admixture according to the present invention may further contain a retention aid as a retention component, in addition to the polycondensate described above. The additional inclusion of retention aids suppresses the aging of the concrete and allows better control of the workability of the concrete over a longer period of time. As a result, it is possible to further suppress the deterioration of the fluidity and the state with the elapsed time. The content of such a retention aid is preferably 5 to 50% by mass with respect to the total mass of the polycondensate in the admixture.

  For example, a copolymer formed by polymerizing a hydrolyzable monomer, an ethylenically unsaturated monomer containing a polyoxyalkylene group, and a cement adsorptive monomer as one of such holding aids It is preferred to use combination 1).

(Hydrolyzable monomer)
The hydrolyzable monomer is preferably an ethylenically unsaturated monomer capable of forming a hydrolyzable monomer residue. As such a hydrolysable monomer, for example, alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate and the like;
Hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and the like;
And (meth) acrylamide and derivatives thereof; and maleic acid (mono) alkyl ester, maleic anhydride, maleimide, etc., but not limited thereto. These may be used alone or in combination of two or more.

(Ethylenic unsaturated monomer containing polyoxyalkylene group)
As an ethylenically unsaturated monomer containing a polyoxyalkylene group, a saturated monocarboxylic acid ester derivative such as polyethylene glycol mono (meth) acrylate, polypropylene glycol (meth) acrylate, polybutylene glycol (meth) acrylate, polyethylene glycol polypropylene glycol Mono (meth) acrylate, polyethylene glycol polybutylene glycol mono (meth) acrylate, polypropylene glycol polybutylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, Methoxy polypropylene glycol mono (meth) acrylate, Xylopolybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol polypropylene glycol mono (meth) acrylate, methoxypolyethylene glycol polybutylene glycol mono (meth) acrylate, methoxypolypropylene glycol polybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol polypropylene glycol Polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, ethoxy polypropylene glycol mono (meth) acrylate, ethoxy polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol polypropylene glycol mono (meth) acrylate, ethoxy polyethylene The Call polybutylene glycol mono (meth) acrylate, ethoxy polypropylene glycol polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) acrylate, and higher alkoxy derivatives of the above polyoxyalkylene;
Vinyl alcohol derivatives such as polyethylene glycol mono (meth) vinyl ether, polypropylene glycol mono (meth) vinyl ether, polybutylene glycol mono (meth) vinyl ether, polyethylene glycol polypropylene glycol mono (meth) vinyl ether, polyethylene glycol polybutylene glycol mono (meth) Vinyl ether, polypropylene glycol polybutylene glycol mono (meth) vinyl ether, polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) vinyl ether, methoxy polyethylene glycol mono (meth) vinyl ether, methoxy polypropylene glycol mono (meth) vinyl ether, methoxy polybutylene glycol mono ( Meta) vinyl Ter, methoxy polyethylene glycol polypropylene glycol mono (meth) vinyl ether, methoxy polyethylene glycol poly butylene glycol mono (meth) vinyl ether, methoxy polypropylene glycol poly butylene glycol mono (meth) vinyl ether, methoxy polyethylene glycol polypropylene glycol poly butylene glycol mono (meth) vinyl ether , Ethoxypolyethylene glycol mono (meth) vinylether, ethoxypolypropylene glycol mono (meth) vinylether, ethoxypolybutylene glycol mono (meth) vinylether, ethoxypolyethyleneglycol polypropylene glycol mono (meth) vinylether, ethoxypolyethylene glycol polybutylene glycol Mono (meth) vinyl ether, ethoxy polypropylene glycol polybutylene glycol mono (meth) vinyl ether, and ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) vinyl ether;
(Meth) allyl alcohol derivatives such as polyethylene glycol mono (meth) allyl ether, polypropylene glycol mono (meth) allyl ether, polybutylene glycol mono (meth) allyl ether, polyethylene glycol polypropylene glycol mono (meth) allyl ether, polyethylene glycol Polybutylene glycol mono (meth) allyl ether, polypropylene glycol polybutylene glycol mono (meth) allyl ether, polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) allyl ether, methoxypolyethylene glycol mono (meth) allyl ether, methoxypolypropylene glycol mono (Meth) allyl ether, methoxypolybutylene glycol mono (meth) Allyl ether, methoxy polyethylene glycol polypropylene glycol mono (meth) allyl ether, methoxy polyethylene glycol poly butylene glycol mono (meth) allyl ether, methoxy polypropylene glycol poly butylene glycol mono (meth) allyl ether, methoxy polyethylene glycol polypropylene glycol poly butylene glycol mono (Meth) allyl ether, ethoxypolyethylene glycol mono (meth) allyl ether, ethoxypolypropylene glycol mono (meth) allyl ether, ethoxy polybutylene glycol mono (meth) allyl ether, ethoxy polyethylene glycol polypropylene glycol mono (meth) allyl ether, ethoxy Polyethylene glycol polybutylene Recall mono (meth) allyl ether, ethoxy polypropylene glycol polybutylene glycol mono (meth) allyl ether and ethoxy polyethylene glycol polypropylene glycol polybutylene glycol mono (meth) allyl ether;
Adducts of alkylene oxide and unsaturated alcohol, for example, polyethylene glycol mono (3-methyl-3-butenyl) ether, polyethylene glycol mono (3-methyl-2-butenyl) ether, polyethylene glycol mono (2-methyl-3-ether) Butenyl) ether, polyethylene glycol mono (2-methyl-2-butenyl) ether, polyethylene glycol mono (1,1-dimethyl-2-propenyl) ether, polyethylenepolypropylene glycol mono (3-methyl-3-butenyl) ether, polypropylene Glycol mono (3-methyl-3-butenyl) ether, methoxypolyethylene glycol mono (3-methyl-3-butenyl) ether, ethoxypolyethylene glycol mono (3-methyl-3-butenyl) ether 1-propoxypolyethylene glycol mono (3-methyl-3-butenyl) ether, cyclohexyloxypolyethylene glycol mono (3-methyl-3-butenyl) ether, 1-octyloxypolyethylene glycol mono (3-methyl-3-butenyl) Ether, nonylalkoxypolyethyleneglycol mono (3-methyl-3-butenyl) ether, laurylalkoxypolyethyleneglycol mono (3-methyl-3-butenyl) ether, stearylalkoxypolyethyleneglycol mono (3-methyl-3-butenyl) ether and Phenoxy polyethylene glycol mono (3-methyl-3-butenyl) ether; and the like, but not limited thereto. The adduct of an alkylene oxide and an unsaturated alcohol is, for example, an adduct of 1 to 350 moles of an alkylene oxide and an unsaturated alcohol, for example, 3-methyl-3-buten-1-ol, 3-methyl-2-butene-. Adducts with unsaturated alcohols such as 1-ol, 2-methyl-3-buten-2-ol, 2-methyl-2-buten-1-ol and 2-methyl-3-buten-1-ol are mentioned But not limited thereto. The above-mentioned ethylenically unsaturated monomers containing a polyoxyalkylene group may be used alone or in combination of two or more.

Ethylenically unsaturated monomers containing such polyoxyalkylene groups can contain oxyalkylene groups having multiple side chain lengths. For example, comprising at least one ethylenically unsaturated carboxylic acid ester or alkenyl ether monomer comprising at least one C _2-4 oxyalkylene group having from 1 to 30 pieces of unit, at least one C ₂ of 31 to 350 pieces of unit _It may contain at least one ethylenically unsaturated carboxylic acid ester or alkenyl ether monomer containing a _-4 oxyalkylene group.

(Cement adsorptive monomer)
The cement adsorptive monomer is preferably an ethylenically unsaturated monomer having a carboxyl group, a sulfone group or a phosphonic group at the end. As the ethylenically unsaturated monomer having a carboxy group, unsaturated carboxylic acid monomers such as (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid and fumaric acid or salts thereof are preferable, and examples thereof include alkali metal salts and alkaline earth metals. Metalloid salts, ammonium salts, amine salts and the like can be mentioned. More preferably, it is (meth) acrylic acid or an alkali metal salt thereof, and still more preferably acrylic acid or its sodium salt. Examples of the ethylenically unsaturated monomer having a sulfone group include (meth) allyl sulfonic acid or salts thereof, such as alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts and the like, preferably (meth) allyl. It is a sodium salt of sulfonic acid, more preferably a sodium salt of methallyl sulfonic acid. As the ethylenically unsaturated monomer having a phosphonic group, mono (2-hydroxyethyl) (meth) acrylic ester phosphate, di- (2-hydroxyethyl) (meth) acrylic ester phosphate and the like are preferable. These may be used alone or in combination of two or more.

  In the copolymer 1, the molar ratio of the hydrolyzable monomer (A), the ethylenically unsaturated monomer (B) containing a polyoxyalkylene group, and the cement-adsorbable monomer (C), that is, (A): (B) ): (C) is preferably 0.5: 1: 0.3 to 10: 1: 10, more preferably 0.5: 1: 0.3 to 5: 1: 5.

  As another holding aid, for example, a copolymer obtained by polymerizing the above-mentioned hydrolyzable monomer and the above-mentioned ethylenically unsaturated monomer containing the polyoxyalkylene group without containing the above-mentioned cement-adsorbable monomer It is preferred to use a combination (copolymer 2). That is, the copolymer 2 does not have a structural unit derived from the above-described cement-adsorbable monomer, and includes a structural unit derived from the above-described hydrolyzable monomer and the above-described polyoxyalkylene group. A copolymer comprising structural units derived from ethylenically unsaturated monomers.

  In the copolymer 2, the molar ratio of the hydrolyzable monomer (A) to the ethylenically unsaturated monomer (B) containing a polyoxyalkylene group, that is, (A) :( B) is preferably 1: 1 to 10: 1, more preferably 1: 1 to 9: 1.

  Other additives can be added to the admixture according to the present invention as needed. Other additives include conventionally used AE agents, polysaccharide derivatives, lignin derivatives, drying shrinkage reducing agents, accelerators, foaming agents, antifoaming agents, antirust agents, quick-setting agents, high water solubility Molecular substances and the like can be mentioned. Other additives may be contained as part of the components of the admixture according to the present invention, or may be added to concrete separately from the admixture according to the present invention. When making it a part of component of the admixture based on this invention, it is limited to the range which does not inhibit the effect of this invention, and it is preferable to contain 1-20 mass% with respect to the admixture based on this invention.

<Cement composition>
The cement composition according to the present invention contains the above-mentioned admixture, and commercially available cement can be used as the cement. Among such cements, it is preferable to use ordinary Portland cement and / or moderate heat, low heat cement from the viewpoint of versatility. In the present invention, ordinary portland cement is particularly preferable in terms of the durability of the obtained cement composition and the cost due to the reduced addition amount of the cement additive.

(Other powder)
Fine powder admixtures such as limestone powder, calcium carbonate, silica fume, ground granulated blast furnace slag, and fly ash can be added as a partial substitute for or addition to cement contained in the cement composition. These powders have a compounding amount of 1 to 100 kg in 1 m ^{3 of} cement composition in order to suppress material separation, maintain appropriate viscosity and high fluidity, and in the range that does not interfere with the effects of the present invention. It is preferable that it is / m ³ .

(aggregate)
In the present invention, low-quality fine aggregate with low angular grain shape and low water retention capacity is used for comparison with rounded and rounded natural aggregate. As examples of low quality fine aggregate, crushed sand and slag fine aggregate can be mentioned. From the viewpoint of securing flowability, such fine aggregate preferably has an appropriate particle size distribution, and the aggregate specified in JIS A 5308: 2014 Appendix A ready mixed concrete aggregate is preferable. It is preferable to have a particle size distribution. Moreover, fine aggregate, such as mountain gravel, river gravel, sea gravel, crushed stone, etc., can also be used as coarse aggregate. The coarse aggregate is generally relatively larger than the fine aggregate, and the fine aggregate preferably has a particle size distribution in the range of less than 5 mm, preferably less than 0.15 mm and less than 5 mm, while the coarse aggregate is preferably It is preferable to have a particle size distribution in the range of 5 mm or more, preferably 5 mm or more and 40 mm or less.

<Concrete type>
The admixture according to the present invention can be applied to a cement composition containing low quality fine aggregate such as crushed sand and slag fine aggregate. If it is a concrete in which such a cement composition is used, the blending conditions of these fine aggregates in the concrete are not particularly limited, but the amount of powder in the concrete is smaller than usual and inferior in water retention capacity As a condition, it is preferable that the present invention is applied to so-called poor-blended concrete in which the total amount of powder in the concrete is blended to 300 kg / m ³ or less.

<Manufacturing of concrete>
The cement composition according to the present invention can be manufactured by a conventionally known method, for example, according to the concrete standard specification book established by the Japan Society of Civil Engineers and the standard specification of building construction prepared by the Japan Architectural Institute of Japan. It can be produced by known equipment and known methods. Specifically, after the admixture according to the present invention is added to kneading water in advance, other raw materials such as cement, aggregate and the like are added to the mixer for manufacturing, or all the raw materials contained in the cement composition The method of putting into a mixer collectively and manufacturing is preferable. The cement composition according to the present invention is preferably produced in a ready-mixed plant in accordance with JIS A 5308.

  Hereinafter, the admixture according to the present invention and the cement composition using the same will be described in detail by way of examples. The present invention is not limited to the examples shown below.

  Concrete was manufactured from the cement composition of the compounding conditions shown in Table 2 using the use materials shown in Table 1. The obtained concrete slump, V funnel down time was measured, and the state of the slump was visually observed.

<Material used>

<Composition of cement composition>

<How to mix>
Among the above materials, cement (C) and aggregates (S1, S2, G) are put into a two-axis forced mixer mixer SD-55 made by Pacific Kiko Co., Ltd. and air-kneaded for 60 seconds, and the mixing is once stopped Water (W) and admixture (SP1, SP2) were added, and the mixture was further kneaded for 60 seconds to obtain concrete. Each addition amount of the admixture (SP1, SP2) was adjusted by the compounding amount shown in Table 3, and was adjusted to the target slump value.

<Measurement and evaluation>
The slump values immediately after mixing (0 minutes) and after 60 minutes, and the V funnel down time were measured, and the state of the slump visually observed. Evaluation of each item was performed as follows.

<Slump>
The slump value was measured based on JIS A 1101: 2014. The amount of decrease in slump after 60 minutes immediately after mixing was used to evaluate the flowability with elapsed time. When the amount of decrease in slump after 60 minutes was 5 cm or less, it was evaluated as "o" which is excellent in fluidity.

<Slump state>
The deformation behavior of the slump in the slump test was classified into the following three by visual observation of the measurer and evaluated as a state.
"◎" excellent: "一体" integrally deformed as "good": the slump collapsed slightly, but "×" separated as a whole integrated: slump collapsed and deformed

<V funnel down time>
The V funnel flow-down time was measured based on JSCE-F 512: 2007, and was classified into the following three according to the increase (difference) in V funnel flow-down time 60 minutes after immediately after mixing, and evaluated as viscosity. If it is "O" or more, the increase in viscosity with the passage of time was suppressed, and it was judged that the ink had a suitable viscosity.
"◎" excellent: less than 5 seconds "○" good: 5 seconds or more and less than 10 seconds "×" defect: 10 seconds or more or blocked

  The test results are shown in Table 3. In addition, the addition amount of each component in Table 3 means the mass% with respect to cement.

  When concrete with SP1 added (hereinafter referred to as “SP1 kon”) and concrete added with SP2 (hereinafter referred to as “SP2 kon”) are compared, as in the reference example 1 and reference example 2, as a fine aggregate When SP1 kon and SP2 kon are produced respectively from a cement composition containing “S1” which is a natural fine aggregate, the reduction amount of slump after 60 minutes is within 5 cm in all, and the flow with elapsed time It was excellent in sex. On the other hand, in the comparison of the slump condition after 60 minutes, the SP1 controller was superior to the SP2 controller in the slump condition. Also, while the increase in V funnel flow-down time after 60 minutes was 6.4 seconds for SP2 con, the increase in V funnel flow-off time for SP1 kon is lower than that for SP2 con, only 2.6 seconds. Met. Therefore, in SP1 computer, it was also possible to suppress the increase in viscosity with the passage of time.

  On the other hand, as in Example 1 and Comparative Example 1, when SP1 kon and SP2 kon are respectively produced from a cement composition containing “S2” which is a fine aggregate of low quality as the fine aggregate, each of them is 60 The drop amount of the slump after 5 minutes was within 5 cm, and the fluidity was excellent. However, while the slump was broken and deformed in the slump state after 60 minutes, the slump was not observed in the SP1 control, and the slump was maintained in an excellent slump state. Further, in the viscosity evaluation test in the SP2 con, occlusion was observed after 60 minutes, but in the SP1 con, occlusion was not observed, and the increase in V funnel flow-down time was also less than 5 seconds. Therefore, in the SP1 controller, it was also possible to suppress the increase in viscosity and the decrease in state with the passage of time.

  Thus, the use of the admixture defined in the present invention for concrete containing low-quality fine aggregate imparts excellent fluidity, and further, the increase in viscosity and state over time. Was able to control the decline of As a result, improvement of pumpability such as pumping loss and pressure dewatering and suppression of bleeding can be brought about.

  By using the admixture defined in the present invention for concrete containing low-quality aggregate such as crushed sand, not only excellent fluidity is exhibited, but also increase in viscosity and decrease in state with elapsed time are suppressed. it can. Therefore, even in an environment where it is necessary to provide concrete using low-quality fine aggregate instead of high-quality fine aggregate by exhaustion of high-quality fine aggregate in recent years, freshness of these concretes It becomes possible to improve the workability while maintaining good.

（式（ＩＩａ）中、
Ｄは、同一であるか、又は異なり、炭素原子を５〜１０個有する、置換若しくは非置換の芳香族又は複素環式芳香族化合物によって表され、
Ｅは、同一であるか、又は異なり、Ｎ、ＮＨ、又はＯであり、ＥがＮであれば、ｍは２であり、ＥがＮＨ又はＯであれば、ｍは１であり、
Ｒ³及びＲ⁴は、相互に独立して、同一であるか、又は異なり、直鎖状若しくは分枝鎖状のＣ₁〜Ｃ₁₀アルキル基、Ｃ₅〜Ｃ₈シクロアルキル基、アリール基、ヘテロアリール基又はＨであり、
ｂは、同一であるか、又は異なり、０〜１０の整数であり、かつ
Ｍａは、相互に独立して、同一であるか、又は異なり、Ｈ又はカチオン等価物である）で表される。上記式（ＩＩａ）において、基「Ｄ」が後述する構造単位（ＩＩＩ）のメチレン単位と結合することより、本発明における混和剤の主成分となる重縮合物が形成される。 The structural unit (II) preferably has the following general formula (IIa):

(In the formula (IIa),
D is the same or different and is represented by a substituted or unsubstituted aromatic or heteroaromatic compound having 5 to 10 carbon atoms,
E is the same or different and is N, NH or O, and when E is N, m is 2 and when E is NH or O, m is 1.
R ³ and R ⁴ are, independently of one another, identical or different, and linear or branched C _{1 to} C ₁₀ alkyl group, C _{5 to} C ₈ cycloalkyl group, aryl group, Heteroaryl or H,
b is the same or different, is an integer of 0 to 10, and Ma is mutually independently, the same or different, and is represented by H or a cation equivalent. In the above formula (IIa), a polycondensate which is a main component of the admixture in the present invention is formed by bonding the group "D" to a methylene unit of the structural unit (III) described later.

The phosphoric acid ester represented by the formula (IIa) may be an acid having two acidic protons (Ma = H). Phosphoric esters can also be present in deprotonated form, in which case the protons are replaced by cation equivalents. The phosphate ester may be partially deprotonated. The term "cation equivalent" refers to any metal cation or ammonium cation (which can replace a proton) which may be substituted, but the molecule is electrically neutral. Ma is preferably NH ₄ , an alkali metal or a half alkaline earth metal.

Claims (6)

A polycondensate having at least one structural unit (I), at least one structural unit (II) and at least one structural unit (III),
The structural unit (I) is an aromatic moiety having a polyether side chain having an alkylene glycol unit, provided that the number of ethylene glycol units in the polyether side chain is 9 to 41, and the ethylene glycol unit The content of units is more than 80 mol% with respect to all the alkylene glycol units in the polyether side chain,
The structural unit (II) is an aromatic moiety having at least one phosphate group and / or a salt thereof, provided that the value of the molar ratio of the structural unit (I) to the structural unit (II) is , 0.3-4,
The structural unit (III) is at least one methylene unit (—CH ₂ —), and the methylene unit is bonded to two aromatic structural units, the structural unit (I) and the structural unit (II) Wherein said aromatic structural units are, independently of one another, identical or different, and
Admixture for low-quality fine aggregate-containing concrete, wherein the mass average molecular weight Mw of the polycondensate containing the structural units (I), (II) and (III) is in the range of 3,000 to 50,000. . The polycondensate further comprises at least one structural unit (IV),
The structural unit (IV) is represented by an aromatic structural unit different from the structural unit (I) and the structural unit (II),
The methylene unit is bonded to the three aromatic structural units of the structural unit (I), the structural unit (II) and the structural unit (IV), wherein the aromatic structural units are independent of each other Identical or different, and
The blend according to claim 1, wherein the weight average molecular weight Mw of the polycondensate containing the structural units (I), (II), (III) and (IV) is in the range of 3,000 to 50,000. Agent.   The admixture according to claim 1, further comprising a retention aid.   The blend according to claim 3, wherein the retention aid is a copolymer obtained by polymerizing a hydrolyzable monomer, an ethylenically unsaturated monomer containing a polyoxyalkylene group, and a cement-adsorbable monomer. Agent.   The copolymer according to claim 3, wherein the retention aid is a copolymer formed by polymerizing a hydrolyzable monomer and an ethylenically unsaturated monomer containing a polyoxyalkylene group without containing a cement-adsorbable monomer. Admixture of.   A cement composition comprising the admixture according to any one of claims 1 to 5.