JP5168497B2 - Shrinkage reducing agent for cement - Google Patents

Description

  The present invention relates to a shrinkage reducing agent for cement concrete mainly used in the civil engineering and construction fields.

  In the field of civil engineering and architecture, cracks are a major issue because they cause early deterioration of concrete. As a method for preventing such cracking of concrete, a method of adding a shrinkage reducing agent during kneading of cements with other additives and water is known.

  However, when a large amount of a shrinkage reducing agent is added to suppress drying shrinkage, air entrainment tends to increase, and in order to obtain a cement composition having a desired amount of air, a process such as adding an antifoaming agent is performed. It was necessary to carry out and preparation was very difficult.

In order to solve these increases in air entrainment, alkanediols and polyalkylene glycols having relatively small air entrainment have been developed (for example, Patent Documents 1 and 2). However, alkanediols and polyalkylene glycols need to add a large amount of shrinkage reducing agent in order to obtain a desired shrinkage reducing effect. When adding a large amount of alkanediols, there is a problem of causing a delay in setting, and when adding a large amount of polyalkylene glycols, there is a problem of causing a decrease in strength.
Japanese Patent Laid-Open No. 01-108138 JP 59-21557 A

  The present invention has been made for the purpose of providing a shrinkage reducing agent that improves the above problems and suppresses drying shrinkage without affecting air entrainment or setting delay.

The present invention
[1] A shrinkage reducing agent for cement, comprising a polyoxyalkylene compound represented by the formula (1).
R ¹ (OA ² ) _m (OA ¹ ) _y —O—X—O— (A ¹ O) _z (A ² O) _n R ² (1)
[However, X is a residue obtained by removing a hydroxyl group from an alkanediol having 2 to 6 carbon atoms.
R ¹ and R ² are each independently a hydrogen atom or a methyl group.
A ² O is an oxyethylene group and an oxyalkylene group having 3 carbon atoms, and may be added in a block form or in a random form.
A ¹ O is composed of one or two or more oxyalkylene groups having 4 to 6 carbon atoms, and when it is two or more, it may be added in a block shape or in a random shape.
m and n are average addition mole number of the oxyalkylene group having 2 and 3 carbon atoms atoms ^(A 2 O), m + n is 2 to 30.
y and z are the average added mole numbers of an oxyalkylene group having 4 to 6 carbon atoms (A ¹ O), and y + z is 1 to 10. ]
[2] The shrinkage reducing agent according to [1], wherein A ¹ O in the formula (1) is an oxybutylene group.
[3] The shrinkage according to [1] or [2], wherein X in the formula (1) is a residue obtained by removing a hydroxyl group from 1,2-ethanediol, 1,2-propanediol, or 1,2-butanediol. It is a reducing agent.
[4] The shrinkage reducing agent according to any one of [1] to [3], wherein the oxyethylene group in A ² O in the formula (1) is 20 to 95 mol%.
[5] The shrinkage reducing agent according to any one of [1] to [4], wherein R ¹ and R ² in the formula (1) are hydrogen atoms.

  Since the cement composition using the cement shrinkage reducing agent of the present invention has a small effect on air entrainment compared to the case where a conventional cement shrinkage reducing agent is added, the adjustment of the air amount becomes extremely easy, Since the influence on the setting delay is small, it is not necessary to suppress the setting delay by adding an accelerator.

  In the formula (1), X is a residue obtained by removing a hydroxyl group from an alkanediol having 2 to 6 carbon atoms. Alkanediols include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3 -Butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5 -Pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-1,2-butanediol, 2-methyl-1,3-butanediol, 2-methyl-1,4-butanediol 2-methyl-2,3-butanediol, 2-ethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,2-he Sundiol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexane Diol, 3,4-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4- Pentanediol, 3-methyl-2,5-pentanediol, 2-ethyl-1,3-butanediol, 2- (n-propyl) -1,3-propanediol, 2-methyl-2-ethyl-1, 3-propanediol, preferably 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 2,2-dimethyl-1,3-propyl Propanediol, 2-methyl-2,4-pentanediol, more preferably 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol.

In the formula (1), A ² O is both an oxyethylene group and a C 3 oxyalkylene group.

Examples of the oxyalkylene group having 3 carbon atoms include a 1,2-oxypropylene group and a 1,3-oxypropylene group, and a 1,2-oxypropylene group is preferable. The addition form of the oxyalkylene group represented by A ² O may be random or block.

  The average added mole number of the oxyalkylene group represented by m + n in formula (1) is 2 to 30, preferably 2 to 20, and more preferably 2 to 15. The ratio of the oxyethylene group in m + n is 20 to 95 mol%, preferably 40 to 80 mol%. Within this range, the effect of suppressing drying shrinkage is great. When the proportion of the oxyethylene group is less than 20 mol%, the solubility in water is impaired, the shrinkage reducing agent becomes non-uniform, and the suppression of shrinkage tends to be hindered.

In the formula (1), examples of the oxyalkylene group having 4 to 6 carbon atoms represented by A ¹ O include a 1,2-oxybutylene group, a 2,3-oxybutylene group, a 1,4-oxybutylene group, Examples include 1,2-oxypentylene group, 2,3-oxypentylene group, 1,2-oxyhexylene group, 2,3-oxyhexylene group, 3,4-oxyhexylene group, and the like. 1,2-oxybutylene group, 1,2-oxypentylene group, 1,2-oxyhexylene group, more preferably 1,2-oxybutylene group. The oxyalkylene group having 4 to 6 carbon atoms may be used alone or in combination of two or more. In the case of two or more, the addition form may be random or block. In formula (1), the average added mole number of the oxyalkylene group having 4 to 6 carbon atoms represented by y + z is 1 to 10, preferably 1 to 8, and more preferably 1 to 5.

In the formula (1), R ¹ and R ² are a hydrogen atom or a methyl group, preferably a hydrogen atom.

In the polyoxyalkylene compound represented by the formula (1) in which R ¹ and R ² are hydrogen atoms, an alkylene oxide having 4 to 6 carbon atoms is added to an alkanediol having 2 to 6 carbon atoms, and then ethylene oxide and carbon atoms are added. It can be produced by addition polymerization of 3 alkylene oxides. As a catalyst for addition polymerization of alkylene oxide, alkali catalysts such as alkali metals and alkaline earth metals, their hydroxides and alcoholates, and Lewis acid catalysts are used. Examples of the alkali catalyst include sodium, potassium, sodium potassium amalgam, sodium hydroxide, potassium hydroxide, sodium hydride, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide and the like, and Lewis acid catalyst. For example, tin tetrachloride, boron trifluoride, boron trifluoride diethyl ether complex, boron trifluoride di n-butyl ether complex, boron trifluoride tetrahydrofuran complex, boron trifluoride phenol complex, boron trifluoride acetic acid complex, etc. And boron trifluoride compound. The addition amount of the catalyst is 0.01 to 10% by mass, more preferably 0.01 to 1% by mass, based on the total weight of the polyoxyalkylene compound represented by the formula (1) and the alkylene oxide subjected to the reaction. .

C 4-6 alkylene oxide, followed by ethylene oxide and C 3 alkylene oxide are added to a mixture of these catalysts and the alkanediol under a nitrogen gas atmosphere, and R ¹ and R ² are hydrogen atoms. A polyoxyalkylene compound of the formula (1) can be obtained. The temperature for addition polymerization of alkylene oxide is 50 to 150 ° C., preferably 60 to 140 ° C., more preferably 80 to 140 ° C., and the nitrogen gas pressure is 0 to 10 kPa, preferably 0.05 to 8 kPa. is there.

The polyoxyalkylene compound represented by the formula (1) in which R ¹ and R ² are methyl groups reacts with methyl halide after the production of the polyoxyalkylene compound in which R ¹ and R ² are hydrogen atoms in the formula (1). By doing so, it can be manufactured. As the catalyst for the reaction with methyl halide, alkali catalysts such as alkali metals and alkaline earth metals, their hydroxides and alcoholates are used. Specific examples include sodium, potassium, sodium potassium amalgam, sodium hydroxide, potassium hydroxide, sodium hydride, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide and the like. Examples of the methyl halide include methyl fluoride, methyl chloride, methyl bromide, and methyl iodide.

In the presence of these catalysts, methyl halide and a polyoxyalkylene compound represented by the formula (1) in which R ¹ and R ² are hydrogen atoms are reacted in a nitrogen gas atmosphere to remove salts and used catalysts. Thus, a polyoxyalkylene compound represented by the formula (1) in which R ¹ and R ² are methyl groups can be obtained. The temperature at the time of reaction with methyl halide is 40 to 150 ° C., preferably 50 to 140 ° C., more preferably 60 to 130 ° C., and the nitrogen gas pressure is 0 to 10 kPa, preferably 0.05 to 8 kPa. is there.

By adjusting the amount of methyl halide charged, the ratio of R ¹ and R ² to a methyl group can be adjusted.

  The shrinkage reducing agent of the present invention is used by being added to cement or a cement blend. Examples of cement blends include mortar and concrete.

  As the cement to which the shrinkage reducing agent of the present invention can be applied, normal, early strength, very early strength, low heat and moderate heat Portland cement, and blast furnace slag, fly ash, or silica are mixed with these Portland cements. Various mixed cements, eco-cements, white cements, super-hard cements, silica fume, fly ash, and those with pozzolanic reaction such as silicate white clay, Portland cement mixed with blast furnace slag fine powder, limestone fine powder, etc. Examples thereof include mixed filler cement, alumina cement, magnesia cement, and white cement.

  The aggregate to which the shrinkage reducing agent of the present invention can be applied is not particularly limited as long as it can be used for ordinary mortar and concrete, and fine sand such as river sand, land sand, crushed sand, and sea sand. Examples include aggregates, coarse aggregates such as river gravel, crushed stone, and artificial lightweight aggregates.

  The method for using the shrinkage reducing agent of the present invention is not particularly limited. When the shrinkage reducing agent is mixed into the cement composition by a mixer, cements, aggregates, water and additives may be added individually, or may be added alone and kneaded.

The shrinkage of the cement cured product can be reduced by bringing the shrinkage reducing agent into contact with and penetrating the cement cured product. In this case, after setting and curing, a shrinkage reducing agent is applied, sprayed and sprayed on the surface of the cured product using a brush, a roller, a sprayer, a sprayer or the like. The application amount, application amount, and spray amount of the shrinkage reducing agent can be set to 0.1 to 1000 g per 1 m ² area, for example.

  When the shrinkage reducing agent of the present invention is added to a cement composition and set, the amount of the shrinkage reducing agent of the present invention is preferably 0.05 to 10% by mass with respect to 100 parts by mass of the cementitious material. More preferably, it is 0.1-5 mass%, More preferably, it is 0.2-3 mass%. By increasing the amount of the shrinkage reducing agent, the effect of suppressing drying shrinkage becomes more remarkable. The intensity | strength of a hardening body can be improved because the quantity of a shrinkage | contraction reducing agent shall be 10 mass% or less.

The amount of aggregate in the cement blend can be determined according to the blending application, but is generally preferably 50 to 1200 parts by weight with respect to 100 parts by weight of cement.
The amount of water in the cement blend can be determined according to the blending application, but generally 10 to 70 parts by weight is preferable with respect to 100 parts by weight of cement.

  The shrinkage reducing agent of the present invention can be used in combination with other additives. Other additives include water reducing agents, AE agents, AE water reducing agents, air volume regulators, setting retarders, setting accelerators, swelling agents, fluidizing agents, foaming agents, water retention agents, thickeners, waterproofing agents. Etc. Examples of water reducing agents include naphthalene sulfonic acid formaldehyde condensate salt, melamine sulfonic acid formaldehyde condensate salt, lignin sulfonic acid salt, aromatic amino sulfonic acid formaldehyde condensate salt, polycarboxylic acid type, and the like. Preferably, it is a salt of a naphthalenesulfonic acid formaldehyde condensate or a polycarboxylic acid type.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
A stainless steel 5 L high-pressure reactor equipped with a stirrer, pressure gauge, thermometer, safety valve, gas blowing pipe, exhaust pipe, cooling coil and steam jacket was charged with 76 g (1.0 mol) of 1,2-propanediol and Sodium hydroxide 1.0 g was charged, and the inside of the system was replaced with nitrogen gas. Under stirring, under conditions of 100 to 120 ° C. and 0.05 to 0.5 MPa (gauge pressure), 144 g (2.0 mol) of 1,2-butylene oxide was added under pressure by nitrogen gas pressure from a pressure vessel prepared separately. did. After completion of the addition, the reaction was continued under the same conditions until the internal pressure became constant, and the treatment was performed at 70-80 ° C. under 13 kPa (gauge pressure) for 1.0 hour while blowing nitrogen gas, and then 0.05 MPa with nitrogen gas. Pressurized to (gauge pressure). After pressurization, under the conditions of 100 to 120 ° C. and 0.05 to 0.5 MPa (gauge pressure), 176 g (4.0 mol) of ethylene oxide and 232 g (4.0 mol) of 1,2-propylene oxide were prepared from a pressure vessel prepared separately. Mol) was pre-mixed under nitrogen gas pressure. After completion of the addition, the reaction was continued under the same conditions until the internal pressure became constant, and then the treatment was performed at 70 to 80 ° C. and 13 kPa (gauge pressure) or less for 1.0 hour while blowing nitrogen gas, and then 0% with nitrogen gas. The pressure was increased to 0.05 MPa (gauge pressure), and 502 g (0.80 mol) of the reaction product was extracted into a 1 L eggplant flask. Thereafter, the solution was neutralized with 1% hydrochloric acid to remove water and by-produced salts to obtain the target polyoxyalkylene compound.

  Mortar was adjusted using the obtained polyoxyalkylene compound. For the preparation method, 450 g of cement [ordinary Portland cement] and 1,350 g of fine aggregate [standard sand for cement strength test] were weighed in a mortar mixer described in JIS R5201, and after kneading for 15 seconds at low speed, Table 1 9.0 g of a polyoxyalkylene compound represented by the formula, an antifoaming agent (dishome CC-118 manufactured by NOF Corporation) in an amount shown in Table 1 and a total of 225 g of tap water. The aqueous solution was added and kneaded at low speed for 45 seconds, and then kneaded at high speed for 1 minute to prepare a mortar. These mortars were prepared with the above-described antifoaming agent so that the air amount was 4.0 ± 0.3%, and the temperature was confirmed to be 21 ± 2 ° C. These operations were repeated, a length change test was performed using one mortar, and a setting test was performed using the other mortar.

(Length change test)
After the prepared mortar was packed in a 40 mm × 40 mm × 160 mm mold, it was subjected to air curing at 20 ° C. and a humidity of 60% for 24 hours and then demolded to obtain a cured mortar specimen.
The mortar cured product specimen obtained as described above was subjected to JIS after demolding.
The length of the mortar cured product specimen was measured based on A1129-3 (mortar and concrete length change test method, dial gauge method). After the measurement, the sample was stored at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%, and the length after 35 days was measured. The drying shrinkage ratio was calculated from the measurement result and formula (2). The obtained results are shown in Table 1.

(Condensation test)
The adjusted mortar is transferred to a stainless steel cylinder with an inner diameter of 16.0 cm and an inner height of 5.0 cm. The resulting mortar is measured for the initial and final times of setting based on JIS A1147 (Concrete setting time test method). went. The results are shown in Table 1.

(Examples 2 to 13)
Antifoaming agent (Dishome CC-118, NOF Corporation) 1% aqueous solution, polyoxyalkylene compound represented by the formula (1) was changed in the same manner as in Example 1 except that the polyoxyalkylene compound shown in Table 1 was used. An oxyalkylene compound and a mortar were obtained, and a length change test and a setting test were performed. The obtained results are shown in Table 1.

(Comparative Example 1)
Measured 450 g of cement [ordinary Portland cement] and 1,350 g of fine aggregate [standard sand for cement strength test] in a mortar mixer described in JIS R5201, and after kneading at low speed for 15 seconds, it is shown in Table 1. Add a 1% aqueous solution of Disfoam CC-118 (manufactured by NOF Corporation) and an aqueous solution prepared to a total of 225 g of tap water, knead at low speed for 45 seconds, and then rotate at high speed And kneaded for 1 minute to prepare a mortar. These mortars were prepared with the above-described antifoaming agent so that the air amount was 4.0 ± 0.3%, and the temperature was confirmed to be 21 ± 2 ° C. These operations were repeated, a length change test was performed using one mortar, and a setting test was performed using the other mortar. The length change test and the setting test were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Examples 2-7)
A mortar was obtained in the same manner as in Example 1 except that the amount of the antifoaming agent (Dishome CC-118 manufactured by NOF Corporation) 1% aqueous solution and the compound represented by the formula (1) were changed as shown in Table 1. A length change test and a setting test were conducted. The obtained results are shown in Table 1.

  From the above results, it can be seen that the shrinkage reducing agent of the present invention can suppress shrinkage without affecting the setting time and air entrainment.

That is, Comparative Examples 2, 3, and 7 cause a setting delay, while Comparative Example 2 has a high air entrainment property, while Examples 1 to 13 that are the shrinkage reducing agents of the present invention do not cause a setting delay and air entrainment. It turns out that it does not affect sex. Moreover, the comparative example 3 which does not contain a C2-C3 oxyalkylene group, the comparative example 4 whose average addition mole number of a C2-C3 oxyalkylene group exceeds 30, and does not contain a C3-oxygen group When compared with Comparative Example 5 and Comparative Example 6 that does not contain an oxyalkylene group having 4 to 6 carbon atoms and other comparative examples, it can be seen that Examples 1 to 13 have a high effect of suppressing shrinkage because the drying shrinkage ratio is small.

Claims (5)

A shrinkage reducing agent for cement, comprising a polyoxyalkylene compound represented by the formula (1)
R ¹ (OA ² ) _m (OA ¹ ) _y —O—X—O— (A ¹ O) _z (A ² O) _n R ² (1)
[However, X is a residue obtained by removing a hydroxyl group from an alkanediol having 2 to 6 carbon atoms.
R ¹ and R ² are each independently a hydrogen atom or a methyl group.
A ² O is an oxyethylene group and an oxyalkylene group having 3 carbon atoms, and may be added in a block form or in a random form.
A ¹ O is composed of one or two or more oxyalkylene groups having 4 to 6 carbon atoms, and when it is two or more, it may be added in a block shape or in a random shape.
m and n are the average added moles of A ² O, and m + n is 2-30.
y and z are the average added moles of A ¹ O, and y + z is 1-10. ] The shrinkage reducing agent according to claim 1, wherein A ¹ O in the formula (1) is an oxybutylene group.   The shrinkage reducing agent according to claim 1 or 2, wherein X in the formula (1) is a residue obtained by removing a hydroxyl group from 1,2-ethanediol, 1,2-propanediol or 1,2-butanediol. The ratio of oxyethylene groups occupied in A ^{2 O} in the formula (1) is 20 to 95 mol%, the shrinkage reducing agent according to any one of claims 1 to 3. The shrinkage reducing agent according to any one of claims 1 to 4, wherein R ¹ and R ² in the formula (1) are each a hydrogen atom.