JP2005132687A - Shrinkage-reducing agent for cement and cement composition using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shrinkage-reducing agent for cement, which has little effect on the amount of air in a cement composition. <P>SOLUTION: In the shrinkage-reducing agent for cement containing an oxyalkylene compound expressed by general formula (1), the value of HLB of the agent is 7-9. In the formula, R is 1-7C alkyl or 5-6C cycloalkyl groups; A is an ethylene group and/or propylene group; O is oxygen; H is hydrogen; and n is an integer of 1-10. Preferably, R is a methyl group. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a shrinkage reducing agent for cement and a cement composition using the same.

A dry shrinkage reducing agent has been used for a long time in order to suppress dry cracking, which is one of the major drawbacks of mortar and concrete, and examples of the dry shrinkage reducing agent include, for example, alkylene (alcohol having 1 to 4 carbon atoms). Oxide adducts and alkylene oxide adducts of alkyl (having 1 to 4 carbon atoms) phenol are known (Patent Documents 1 and 2).
JP 56-37259 A Japanese Examined Patent Publication No. 62-10947

When conventional shrinkage reducing agents for cement are added to a cement composition, the amount of air in the cement composition is greatly affected by the temperature, and even if an air entraining agent is used to adjust the amount of air, the amount of addition is very small. It is difficult to prepare a cement composition having a desired amount of air because the amount of air greatly changes due to a slight blur.
In addition, conventional shrinkage reducing agents for cement may greatly affect the amount of air in the cement composition when mixed in the cement composition, so care must be taken when cleaning equipment (mixer cars and agitator cars). And a great deal of effort is required.
That is, an object of the present invention is to provide a shrinkage reducing agent for cement that has little influence on the amount of air in the cement composition.

（式中Ｒは炭素数1〜７のアルキル又は炭素数５〜６のシクロアルキル基、Ａはエチレン基及び／又はプロピレン基、Ｏは酸素原子、Ｈは水素原子、ｎは１〜１０の整数を表す。） The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention is a cement shrinkage reducing agent for cement containing an oxyalkylene compound represented by the general formula (1), wherein the HLB is 7 to 9.

(Wherein R is alkyl having 1 to 7 carbon atoms or cycloalkyl group having 5 to 6 carbon atoms, A is an ethylene group and / or propylene group, O is an oxygen atom, H is a hydrogen atom, and n is an integer of 1 to 10) Represents.)

The shrinkage reducing agent for cement according to the present invention has very little influence on the increase or decrease in the amount of air in the cement depending on the temperature and the amount added. Therefore, the cement composition using the cement shrinkage reducing agent of the present invention has a much smaller influence on air entrainment than the conventional cement shrinkage reducing agent, and the amount of air can be adjusted. It becomes extremely easy.

The general formula (1) will be described.
Examples of the alkyl group having 1 to 7 carbon atoms include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, tert-pentyl, and n-hexyl. , Iso-hexyl, n-heptyl, iso-heptyl and the like.
Examples of the cycloalkyl group having 5 to 6 carbon atoms include cyclopentyl, cyclohexyl and methylcyclopentyl.
Of these R, an alkyl group having 1 to 7 carbon atoms is preferable, more preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably methyl, ethyl, n-propyl and iso-propyl, and most preferably methyl. .

A represents ethylene and / or propylene, and AO represents oxyethylene and / or oxypropylene. Any one of oxyethylene and oxypropylene may be used, or a mixture thereof may be used. In the case of a mixture of oxyethylene and oxypropylene, any of a block shape, a random shape and a mixture thereof may be used, but a block shape and a mixture of a block shape and a random shape are preferable, and a block shape is more preferable.

n is preferably an integer of 1 to 10, more preferably an integer of 3 to 10, particularly preferably an integer of 4 to 9, and most preferably an integer of 5 to 8. Within this range, the shrinkage reduction effect is further improved. O represents an oxygen atom, and H represents a hydrogen atom.

The HLB is preferably 7 to 9, more preferably 7.4 to 8.6, particularly preferably 7.6 to 8.4, and most preferably 7.4 to 8.2. That is, the lower limit of HLB is preferably 7, more preferably 7.4, particularly preferably 7.6, most preferably 7.4, and similarly the upper limit is preferably 9, more preferably 8.6, Particularly preferred is 8.4, and most preferred is 8.2.
HLB means Oda-type HLB, which is a value calculated from the ratio between the organic value and the inorganic value of the compound. The details of the calculation are introduced in various literatures related to surfactants. (For example, an introduction to new surfactants, Sanyo Chemical Industries, Ltd., published in 1981, pages 197-198).

Of the oxyalkylene compounds represented by the general formula (1), preferred are those represented by the following chemical formulas. P represents oxypropylene, E represents oxyethylene, CH ₃ O represents a methoxy group, and H represents a hydrogen atom. Moreover, when P and E are included, either a block shape or a random shape may be sufficient. The number in <> shows HLB.

Among these, those represented by the formulas (8) to (15) are more preferable, and the formulas (13) to (15) are particularly preferable.
The oxyalkylene compound represented by the general formula (1) may be used alone or in combination of two or more.

The shrinkage reducing agent for cement according to the present invention is a normal hydraulic cement {ordinary Portland cement, special Portland cement (early strong Portland cement, moderately hot Portland cement), and / or mixed cement (blast furnace cement, fly ash cement, etc.)} It is applicable to a cement composition containing

As the components in the cement composition other than the cement shrinkage reducing agent and cement according to the present invention, those used in mortar or concrete can be applied, kneaded water, aggregate, admixture for cement composition, admixture, etc. Is included.
Examples of the kneaded water include seawater, river water, lake water, tap water, industrial water, and deionized water. Aggregates include fine aggregates and coarse aggregates. As fine aggregates, aggregates conforming to JIS A5308: 1998 Annex 1 (normative) ready-mixed concrete aggregates can be used, such as river sand, land sand, mountain sand, sea sand and crushed sand. It is done. As the coarse aggregate, there can be used an aggregate or the like that conforms to Annex 1 (normative) ready mixed concrete aggregate of JIS A5308: 1998, and examples thereof include river gravel, land gravel, mountain gravel and crushed stone.

Examples of the admixture include fly ash, blast furnace slag, silica fume, and the like.
Admixtures for cement compositions include water reducing agents (AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, fluidizing agents), air entraining agents (AE agents), expansion materials, foaming agents (foaming agents). , Antifoaming agents (foam suppressors, foam breakers), curing accelerators (quick curing agents), retarders, rust inhibitors, thickeners, polymer dispersions for polymer cement concrete or polymer mortar and other miscibility Agents and the like.

As fly ash, JIS A6201: 1999 concrete fly ash can be used, blast furnace slag can be JIS A6206: 1997 concrete blast furnace slag fine powder, silica fume conforming to JIS A6207: 2000 concrete silica fume, and the like can be used.

Examples of water reducing agents include lignin sulfonates (alkaline metal salts such as sodium and alkaline earth metal salts such as calcium; the same applies to salts of the following compounds), naphthalene sulfonic acid formalin condensate (condensation degree: 5 to 5). 20), melamine formalin condensate salt (condensation degree: 5 to 20), polycarboxylic acid salt (number average molecular weight: 5000 to 60,000), aminosulfonic acid formalin condensate salt (condensation degree: 2 to 20), And polyoxyalkylene groups (for example, polyoxyalkylene groups having 2 and / or 3 carbon atoms in the alkylene group) -containing polycarboxylate (number average molecular weight: 10,000 to 600,000) {eg, concrete admixture development technology, CMC Co., Ltd., published in 1995}.

As AE agent, alkyl sulfate ester salt (alkyl group having 10 to 14 carbon atoms), alkyl ether sulfate ester salt (alkyl group having 10 to 14 carbon atoms, alkylene group having 2 carbon atoms), resin Examples include acid salts. Examples of the expansion material include calcium sulfoaluminate and quicklime (for example, Denka CSA, manufactured by Denki Kagaku Kogyo; Asano Gipkar, manufactured by Taiheiyo Material). As the foaming agent, alkyl sulfate ester salt (alkyl group having 10 to 14 carbon atoms), alkyl ether sulfate ester salt (alkyl group having 10 to 14 carbon atoms, alkylene group having 2 carbon atoms, polyoxyalkylene group), Examples thereof include resin acid salts, alkylbenzene sulfonates, and protein foaming agents. Examples of antifoaming agents include ester-based antifoaming agents, polyether-based antifoaming agents, mineral oil-based antifoaming agents, silicone-based antifoaming agents, and powder antifoaming agents (for example, introduction to new surfactants, Sanyo Chemical Industries ( Co., Ltd.), published in 1981, SN deformer 14HP, SN deformer 11-P (manufactured by San Nopco)) and the like. Examples of the curing accelerator include an intramolecular condensate of a polyhydric alcohol (such as pentaerythritol), diethanolamine, triethanolamine and other known curing accelerators, calcium chloride, and the like. Examples of the curing retarder include sugars and oxycarboxylates. Examples of the rust inhibitor include nitrite. Examples of the thickener include polyacrylamide and cellulose ether. Examples of the polymer dispersion for polymer cement concrete or polymer mortar include styrene butadiene rubber latex, ethylene vinyl acetate, and polyacrylate emulsion. As other admixtures, known mortars or concrete admixtures {for example, concrete admixture development technology, CMC Co., Ltd., published in 1995} can be used.

The content (% by weight) of the shrinkage reducing agent for cement according to the present invention is preferably 0.5 to 20, more preferably 1 to 10, particularly preferably 1.5 to 7.5, based on the weight of the cement. Most preferably, it is 2-5. That is, the lower limit of the content (% by weight) of the shrinkage reducing agent for cement of the present invention is preferably 0.5, more preferably 1, particularly preferably 1.5, and most preferably 2 based on the weight of the cement. Similarly, the upper limit is preferably 20, more preferably 10, particularly preferably 7.5, and most preferably 5.

The content of the cement composition admixture may be in a range that is usually used.
In addition, when using a water reducing agent, the usage-amount (weight%, conversion of an active ingredient) of a water reducing agent is preferable 0.1-100 based on the weight of a shrinkage reducing agent, More preferably, it is 2-50, Especially preferably Is 3-30, most preferably 5-20. That is, in this case, the lower limit of the amount of water reducing agent used (% by weight, in terms of active ingredient) is preferably 0.1, more preferably 2, particularly preferably 3, most preferably based on the weight of the shrinkage reducing agent. Similarly, the upper limit is preferably 100, more preferably 50, particularly preferably 30, and most preferably 20.

The means for adding the shrinkage reducing agent for cement of the present invention may be the same as that of a cement admixture that is generally used. For example, after mixing an appropriate amount of a shrinkage reducing agent for cement in kneaded water in advance, or separately together with other raw materials, the mixture may be put into a mixer.

The construction method of the mortar or concrete added and kneaded with the shrinkage reducing agent for cement of the present invention may be the same as in the conventional case. Moreover, as a hardening thru | or curing method, any of an air-drying curing, a wet-air curing, an underwater curing, a heat promotion curing (steam curing, an autoclave curing) may be sufficient, and each combination may be sufficient.

EXAMPLES Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto.
Unless otherwise specified, parts are parts by weight, and% is% by weight.
<Examples 1-6 and Comparative Examples 1-7>
0.25% water reducing agent (Pozoris No. 70: manufactured by NM Co., Ltd.), 0.003% AE agent (Micro Air 303A: manufactured by NM Co., Ltd.) and Table 1 The described shrinkage reducing agent is premixed in kneading water. Cement, standard sand (JIS A5201: 1997 Annex 2 cement test method-sand conforming to strength measurement) and kneaded water adjusted to the material temperature listed in Table 1 and weight ratio of cement 1 The mixture was mixed and kneaded so as to obtain a standard sand 2 and a water cement ratio of 0.45 (kneading water / cement ratio = 0.45) to obtain cement compositions of Examples 1 to 6 and Comparative Examples 1 to 7. .

<Air volume>
Measured in accordance with the mortar air content measurement method defined in JIS A5308: 1998 Annex 3 Mortar Compressive Strength Sand Test Method, the air content was calculated, and the results are shown in Table 1.

<Shrinkage rate>
Each of the cement compositions of Examples 1, 3, 5 or Comparative Example 1 was poured into three 4 × 4 × 16 cm metal molds, demolded after 24 hours, and then kept at 20 ° C. until 7 days of age. It was cured in water and allowed to stand in an atmosphere of 20 ° C. and 65% RH for 7, 14, 21, and 28 days to obtain three specimens E1, E3, E5, and C1, respectively. In each material age, the length of this specimen was measured in accordance with JIS A1129-3: 2001, mortar and concrete length change test method-Part 3 dial gauge method under the atmosphere described on the left, and the shrinkage rate Was calculated as the rate of change in length, and the results are shown in Table 2.

In the table, abbreviations representing shrinkage reducing agents are as follows.
a-1 Methanol PO5 (HLB = 7.4)
a-2 Methanol EO1PO6 (HLB = 8.2)
a-3 Methanol EO1PO7 (HLB = 7.7)
a-4 Methanol EO1PO4 (HLB = 9.8)
a-5 n-propanol PO5 (HLB = 6.5)
a-6 n-butanol PO2EO2 (HLB = 11.2)

表１から、本発明のセメント用収縮低減剤を使用した場合、モルタルの練り上がり温度及び収縮低減剤の添加量による空気連行性への影響が極めて小さいが判る。さらに表２から、本発明のセメント用収縮剤が著しく高い収縮率低減効果を持つことを確認ができた。

Table 1 shows that when the shrinkage reducing agent for cement of the present invention is used, the influence on the air entrainment by the kneading temperature of the mortar and the addition amount of the shrinkage reducing agent is extremely small. Further, from Table 2, it was confirmed that the shrinkage agent for cement of the present invention has a remarkably high shrinkage reduction effect.

The powder additive for a cement composition of the present invention includes a normal hydraulic cement {ordinary Portland cement, special Portland cement (early strong Portland cement, moderately hot Portland cement), and / or mixed cement (blast furnace cement, fly ash cement). ) Etc.}. In particular, compared to the case where a conventional shrinkage reducing agent for cement is added, the influence of the kneading temperature on the air entrainment and the influence of the amount of the shrinkage reducing agent on the air entrainment are small. It is suitable for use in mortar and concrete blending.

Claims (4)

A shrinkage reducing agent for cement, comprising an oxyalkylene compound represented by the general formula (1), wherein HLB is 7 to 9.

(Wherein R is alkyl having 1 to 7 carbon atoms or cycloalkyl group having 5 to 6 carbon atoms, A is an ethylene group and / or propylene group, O is an oxygen atom, H is a hydrogen atom, and n is an integer of 1 to 10) Represents.) The shrinkage reducing agent according to claim 1, wherein R is methyl. A cement composition comprising the shrinkage reducing agent according to claim 1, cement, water, and aggregate. The cement composition according to claim 3, wherein the content of the shrinkage reducing agent is 0.5 to 20% by weight based on the weight of the cement.