JPH0532442A - Cement additive and cement mixture containing the same - Google Patents

Abstract

PURPOSE:To prevent the deterioration of concrete and improve the durability of the concrete by adding an organopolysiloxane having a specific group. CONSTITUTION:(B) A cement additive is characterized by containing (A) an organopolysiloxane having at least one of polyoxyalkylene groups of the formula (R is 1-20C monovalent hydrocarbon group such as methyl, ethyl or propylene; R<1>, R<2>, R<3> are desired groups; (m), (n) are 0 or a positive integer) in the molecule, the organopolysiloxane A being preferably the organopolysiloxane modified with polyoxyalkylene groups comprising CH2CH2 groups/CH2CH(CH3)O groups in a molar ratio of 0-10/1. A cement mixture comprises 0.01-10 pts.wt. of the component B and 100 pts.wt. of cement.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cement admixture or admixture, and more particularly to an excellent cement admixture or admixture which prevents cracking of concrete.

[0002]

2. Description of the Related Art In recent years, deterioration of concrete and mortar has been accelerated due to acid rain, salt damage, frost damage and the like due to environmental changes, and durability of structures using concrete and mortar (hereinafter referred to as concrete) has been reduced.

Deterioration of concrete is generally caused by salt damage and acid rain, and moisture containing chloride ions or acid penetrates into the concrete to neutralize the inside of the concrete and cause rust on the reinforcing bars inside the concrete. As a result, frost damage is caused by a decrease in the strength of the concrete structure due to freezing and expansion of water that has penetrated into the concrete.

Further, cracks in concrete are caused mainly by a decrease in volume called dry shrinkage when the concrete is hardened and dried, and the cracks accelerate deterioration of the concrete, and the concrete structure The deterioration of durability is accelerated.

As a method for preventing such deterioration of concrete (hereinafter, simply referred to as deterioration), a waterproofing agent such as alkoxysilane, alkylalkoxysilane, or organopolysiloxane is applied to the surface of the concrete structure so that the water content inside the concrete is reduced. A method for preventing invasion and preventing deterioration is known (for example, JP-A-1-16088).
6, JP-A-2-16186 and JP-A-2-1504.
77).

Also known is a method of adding a water-repellent compound such as an alkylalkoxysilane, an organopolysiloxane or an organopolysiloxane having a hydrolyzable group to the inside of concrete to prevent water from entering and prevent deterioration. (For example, JP-A-44-13037, JP-A-5-13037)
8-2252 and JP-A-2-160651).

Further, polyoxyalkylene, alkyl ether, polyoxyethylene / oxypropylene copolymer and the like are known as a drying shrinking agent which prevents drying shrinkage to prevent deterioration (for example, JP-B-62-10947). ,
Japanese Patent Publication No. 59-3430 and Japanese Patent Publication No. 56-51148
issue).

[0008]

However, in the method of applying a waterproofing agent to the surface of the concrete structure to prevent deterioration, there is no effect of reducing drying shrinkage and the waterproofing effect decreases over time. Although it is possible to prevent short-term deterioration of concrete, it has a drawback that it is not sufficient to prevent long-term deterioration and improve the durability of the structure.

In addition, even in the method of preventing deterioration by adding the water-repellent compound to the inside of concrete, the effect of preventing drying shrinkage is not clear, but concrete is rendered water-repellent to prevent water from entering and deterioration. The water-repellent compound is inferior in weather resistance and decreases or disappears in a relatively short period of time, so it is sufficient to prevent deterioration over a long period of time and improve the durability of concrete structures. There was a drawback that it was not. Further, there is also a drawback in that concrete strength is lowered when the amount of the water repellent compound added is increased.

Further, in the method of adding the dry shrinkage agent, it is possible to reduce the dry shrinkage of the concrete and prevent the cracking of the concrete. It has a drawback that it is not sufficient to improve the durability of the concrete structure.

Therefore, as a result of intensive studies made by the present inventors in order to solve such a drawback, by mixing a specific organopolysiloxane with cement, the waterproofness of concrete can be improved without lowering the strength of concrete. The present inventors have found that the drying shrinkage can be reduced while achieving the present invention.

Therefore, a first object of the present invention is to improve the waterproofness and the drying shrinkage of the concrete without lowering the strength of the concrete to prevent the deterioration of the concrete and to improve the durability of the concrete structure. It is to provide an excellent cement admixture that can be obtained. It is a second object of the present invention to provide a cement admixture capable of constructing a structure that has a small amount of drying shrinkage, a high waterproof property, and an excellent durability.

[0013]

The above-mentioned various objects of the present invention are represented by the general formula (Formula 3).

[Chemical 3] [In the formula, R is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ¹ , R ² and R ^{3 are represented by the} general formula (Formula 4).

[0014]

[Chemical 4] (In the formula, a is an integer of 0 to 4, b is an integer of 0 or more,
c is an integer of 1 or more. R ⁴ is a hydrogen atom, having 1 to 1 carbon atoms
15 monovalent hydrocarbon groups or acyl groups. ), And m and n are 0 or a positive integer. ],
It is achieved by a cement admixture characterized by containing an organopolysiloxane having at least one polyoxyalkylene group in one molecule, and a cement admixture using the same.

In the present invention, specific examples of R in the formula (3) are, for example, methyl group, ethyl group, propyl group,
Examples thereof include a butyl group, a pentyl group, a phenyl group and a 3,3,3-trifluoropropyl group, and Rs may be the same or different.

Specific examples of the polyoxyalkylene group in the present invention include the groups of the following (formula 5) to (formula 8).

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8] Incidentally, in the polyoxyalkylene group, -CH ₂ CH ₂ O-
Group / -CH ₂ CH (CH ₃₎ molar ratio of O- group 0
Is preferable, and when it is 10 or more, the waterproof property of the admixed concrete is deteriorated, which is not preferable.

The polyoxyalkylene-modified organopolysiloxane used in the present invention comprises an organohydrogenpolysiloxane having a hydrogen atom in which a polyoxyalkylene having a double bond at the molecular end is bonded to the silicon of the organohydrogenpolysiloxane. It can be easily obtained by adding so as to be equal to or in excess of the number of moles and performing an addition reaction in the presence of a platinum-based catalyst.

The molecular weight is preferably in the range of 300 to 30,000. When the molecular weight is 300 or less, the polyoxyalkylene group has a small molecular weight, so that the water retention is poor and the drying shrinkage is large, which is not preferable. Also, the molecular weight is 30,0.
When it is 00 or more, it is disadvantageous in terms of manufacturing cost.

Platinum-based catalysts include platinum black, chloroplatinic acid, a chloroneutralized product of chloroplatinic acid, an alcohol solution of chloroplatinic acid,
It can be appropriately selected and used from known compounds such as a complex of chloroplatinic acid and an olefin or vinyl siloxane.

The addition reaction can be carried out at 30 to 200 ° C., but the reaction temperature is preferably 60 to 110 ° C. from the viewpoint of allowing the intended reaction to proceed rapidly. The reaction can also be carried out in the absence of solvent, but ethanol, isopropanol, toluene,
It is also possible to react using a solvent such as THF, dioxane, ethyl acetate, methyl ethyl ketone.

In general, concrete is obtained by mixing cement, water, bone agent and other additives used as necessary and curing, and the cement admixture of the present invention is added during the above mixing.

The cement that can be used in the present invention is not particularly limited, and ordinary Portland cement, medium and high heat Portland cement, early strength Portland cement, low heat Portland cement, sulfate resistant Portland cement, blast furnace cement, silica cement. ,
It can be used by appropriately selecting from fly ash cement and the like.

Examples of the bone agent include fine bone agent such as river sand, coarse bone agent such as river gravel, and light weight bone agent such as crushed stone. Normally, the mixing ratio of bone agent and cement is 10
It is considered that the bone agent is preferably 3000 parts by weight or less with respect to 0 parts by weight.

In the present invention, further, according to desired physical properties of concrete, as the additive, an AE agent (air entraining agent), a dispersant, a foaming agent, a coloring agent, a quick hardening agent, a setting retarder,
Chemical resistant agents, antifreezing agents, curing agents, etc. can be added. Also, water is usually 2 parts per 100 parts by weight of cement.
It is preferable to add 0 to 80 parts by weight.

The cement admixture of the present invention comprises cement 10
It can be easily produced by adding 0.05 to 10 parts by weight of the admixture of the present invention to 0 parts by weight.
It is particularly preferable to add 0.1 to 5 parts by weight. 0.0
Addition of 5 parts by weight or less makes it impossible to obtain a cement admixture having sufficient waterproofness, and addition of 10 parts by weight or more causes an increase in cost of the cement admixture and is uneconomical.

The cement admixture of the present invention can be used not only by adding the cement admixture as it is, but also as a dispersion liquid in which the cement admixture is dispersed in water, a powder obtained by supporting an inorganic or organic powder. It can be used as a substance, or as a solution dissolved in a solvent or an emulsified emulsion, etc., and easily added to cement by a conventional method.

The cement admixture of the present invention can be easily obtained by mixing the cement, the bone agent, the cement admixture, water, and other additives used as necessary with a mixer or the like. Further, a concrete structure having a specific shape can be easily obtained by pouring the mixture into a mold or coating, impregnating or spraying with another material.

The method of curing the cement composition using the admixture of the present invention is not particularly limited, and it is a conventional method such as a natural curing method at room temperature or a condition of low temperature, high temperature, steam or water. Any method such as the curing method described in 1 above can be adopted as necessary.

[0029]

The cement admixture or cement admixture of the present invention can prevent the deterioration of concrete and improve the durability of the concrete structure without lowering the strength of the concrete.

[0030]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention.

Example 1. Synthesis of Siloxane Compound: A 1-liter flask equipped with a thermometer, a stirrer, and a condenser has an average composition formula of
Compound represented by

[0032]

[Chemical 9] 206 g (0.89 mol), 173 g ethanol and 2.5 wt% isopropanol chloroplatinate solution 0.6
After charging 4 g, the siloxane compound represented by the average composition formula (Chem. 10) while being heated and refluxed

[0033]

[Chemical 10] 165 g (0.74 mol) was added dropwise over 2 hours to complete the reaction. Then, the obtained composition is 80 ° C./3 mm
Siloxane compound whose average composition formula is represented by (Chemical Formula 11) by distilling with Hg to remove ethanol

[Chemical 11] Was obtained in a yield of 80%. 25 of the obtained siloxane compound
The viscosity at 0 ° C. was 15.4 cs, the specific gravity was 0.947, and the refractive index was 1.4292.

Preparation of concrete test pieces: Ordinary Portland cement (referred to as cement) and silica sand were mixed in a weight ratio of 1: 3, and the resulting mixture was mixed with the above siloxane compound in an amount of 3.0 parts by weight per 100 parts by weight of cement. A cement composition was obtained by adding together with water so as to have a ratio of parts and mixing well. The amount of water was added so that the flow value measured according to JIS R5202 would be 160 ± 2 mm.
The water / cement ratio at this time was 0.7.

Then, 40 m of the obtained cement composition
After molding into a rectangular parallelepiped measuring m × 40 mm × 160 mm, JI
SR5201 (Cement physical testing method), JIS A1
404 (Testing method for cement waterproofing agent for buildings) and JIS
Curing was performed according to A1129 (length change test of mortar and concrete) to obtain test pieces corresponding to each test method.

Evaluation of concrete test pieces: The obtained test pieces were subjected to a compressive strength test according to JIS R5201, a waterproof property test according to JIS A1404, and a length change test according to the comparator method of JISA1129. did. The results are as shown in Table 1.

The compressive strength and the dry shrinkage in the table are values measured after 28 days have passed since the test piece was produced, and the water absorption ratio is defined as the additive weight of the test piece after being immersed in water for 24 hours. The increase weight of a test piece (Comparative Example 5) in which No.

Example 2. The compound represented by the average composition formula of (Chemical Formula 9) is the compound represented by the average composition formula of (Chemical Formula 12).

[Chemical 12] A polyoxyalkylene-modified dimethylpolysiloxane was obtained in exactly the same manner as in Example 1 except that Using the obtained polyoxyalkylene-modified dimethylpolysiloxane, a concrete test piece was prepared and evaluated in exactly the same manner as in Example 1. The results are as shown in Table 1.

Example 3. The compound represented by the average composition formula of (Chemical Formula 10) is the compound represented by the average composition formula of (Chemical Formula 13).

[Chemical 13] A polyoxypropylene-modified dimethylpolysiloxane was obtained in the same manner as in Example 1 except that Using the obtained polyoxypropylene-modified dimethylpolysiloxane, a concrete test piece was prepared and evaluated in exactly the same manner as in Example 1. The results are as shown in Table 1.

Comparative Example 1. Synthesis of Siloxane Compound: A 1-liter flask equipped with a thermometer, a stirrer, and a condenser has an average composition formula (Chemical Formula 1
Compound represented by 4)

[0041]

[Chemical 14] After charging 189 g (1 mol), 207 g of ethanol and 0.63 g of a 2.5 wt% isopropanol chloroplatinate solution, the above average composition formula (Chem.
183 g (0.83 mol) of the siloxane compound represented by 0) was added dropwise over 3 hours to complete the reaction. Then, the obtained composition is distilled at 80 ° C./3 mmHg to distill off ethanol to obtain a siloxane compound having an average composition formula (Formula 15).

[0042]

[Chemical 15] Was obtained in a yield of 80%. 25 of the obtained siloxane compound
The viscosity at 0 ° C. was 20.6 cs, the specific gravity was 1.000, and the refractive index was 1.4372. A concrete test piece was prepared and evaluated in exactly the same manner as in Example 1 using the obtained siloxane compound. The results are as shown in Table 1.

Comparative Example 2. A concrete test piece was prepared and evaluated in exactly the same manner as in Example 1, except that the polyoxyalkylene compound represented by the average composition formula (Formula 9) was used in place of the siloxane compound used in Example 1. The results are as shown in Table 1.

Comparative Example 3. A concrete test piece was prepared and evaluated in exactly the same manner as in Example 1, except that the polyoxyalkylene compound represented by the average composition formula (Formula 12) was used in place of the siloxane compound used in Example 1. The results are as shown in Table 1.

Comparative Example 4. Instead of the siloxane compound used in Example 1, a polyoxyalkylene compound represented by the average composition formula of Chemical formula 16

[Chemical 16] Using, the concrete test piece was prepared and evaluated in exactly the same manner as in Example 1. The results are as shown in Table 1.

Comparative Example 5. Concrete test pieces were prepared and evaluated in exactly the same manner as in Example 1 except that no additives were used. The results are as shown in Table 1.

[0047]

[Table 1] ─────────────────────────────────── Example JISR5201 JISA1404 JISA1129 ──────── ──── ──────── ────────── compressive strength Kg / cm ² water absorption ratio drying shrinkage × 10 ^-4 ───────────── ────────────────────── Example 1 320 0.72 4.8 ─────────────────── ───────────────── Example 2 313 0.78 5.2 ─────────────────────── ──────────── Example 3 347 0.65 4.5 ───────────────────────────── ─────── Comparative Example 1 325 0.87 10.3 ──────────── ─────────────────────── Comparative Example 2 288 0.85 9.0 ────────────────── ────────────────── Comparative Example 3 122 0.83 9.5 ─────────────────────── ───────────── Comparative Example 4 135 0.90 8.5 ──────────────────────────── ──────── Comparative Example 5 350 1.00 11.0 ───────────────────────────────── ─── The above results demonstrate that the cement admixture of the present invention enhances waterproofness and reduces drying shrinkage without reducing the compressive strength of concrete.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromi Osaki             28-1 Nishi-Fukushima, Kakubiki Village, Nakakubiki District, Niigata Prefecture               Shin-Etsu Chemical Co., Ltd. (72) Inventor Masayoshi Tanaka             2-6-1 Otemachi, Chiyoda-ku, Tokyo Shin-Etsu             Gaku Kogyo Co., Ltd.

Claims (3)

[Claims] 1. A general formula (Formula 1): [Wherein R is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ¹ , R ² and R ³ are represented by the general formula (Formula 2) (In the formula, a is an integer of 0 to 4, b is an integer of 0 or more,
c is an integer of 1 or more. R ⁴ is a hydrogen atom, having 1 to 1 carbon atoms
15 monovalent hydrocarbon groups or acyl groups. ), And m and n are 0 or a positive integer. ],
A cement admixture containing an organopolysiloxane having at least one polyoxyalkylene group in one molecule. 2. The organopolysiloxane is --CH ₂ C.
H ₂ O-groups _{/ -CH 2 CH (CH 3)} O- group = 0
The cement admixture according to claim 1, which is a (molar ratio) polyoxyalkylene-modified organopolysiloxane. 3. A cement admixture in which the content of the admixture according to claim 1 or 2 is 0.01 to 10 parts by weight based on 100 parts by weight of cement.