JP2704328B2 - Cement admixture and cement admixture using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture or admixture, and more particularly to an excellent cement admixture or admixture for preventing concrete from cracking.

[0002]

2. Description of the Related Art In recent years, concrete and mortar have been rapidly deteriorated due to acid rain, salt damage or frost damage caused by environmental changes, and the durability of structures using concrete and mortar (hereinafter referred to as concrete) has been reduced.

[0003] Deterioration of concrete generally involves, in salt damage or acid rain, moisture containing chloride ions or acids penetrate into the concrete to neutralize the inside of the concrete and cause rust on the reinforcing steel inside the concrete. As a result, the frost damage is caused by the fact that the moisture that has entered the inside of the concrete freezes and expands, thereby causing a decrease in the strength of the concrete structure.

[0004] Cracks in concrete are generally caused mainly by a decrease in volume called drying shrinkage when the concrete is hardened and dried, and the cracks accelerate the deterioration of the concrete, and the concrete structure is deteriorated. Of the durability of is accelerated.

As a method for preventing such deterioration of the concrete (hereinafter simply referred to as deterioration), a waterproofing agent such as an alkoxysilane, an alkylalkoxysilane, or an organopolysiloxane is applied to the surface of the concrete structure, and moisture inside the concrete is reduced. A method of preventing intrusion and preventing deterioration is known (for example, see JP-A-1-16088).
No. 6, JP-A-2-16186 and JP-A-2-1504
No. 77).

There is also known a method in which a water repellent compound such as an alkylalkoxysilane, an organopolysiloxane or an organopolysiloxane having a hydrolyzable group is added to the interior of concrete to prevent moisture from entering and prevent deterioration. (See, for example, JP-A-44-13037,
8-2-2252 and JP-A-2-160651).

Further, polyoxyalkylenes, alkyl ethers, polyoxyethylene / oxypropylene copolymers and the like are known as drying shrinkage agents which prevent drying shrinkage and prevent deterioration (for example, Japanese Patent Publication No. 62-10947). ,
JP-B-59-3430 and JP-B-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 with time. Although it is possible to prevent short-term deterioration of concrete, there is a drawback that it is not enough to prevent long-term deterioration and improve the durability of the structure.

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 known. However, water repellency is imparted to concrete to prevent moisture from penetrating to prevent deterioration. The water-repellent compound is inferior in weather resistance and the water-repellency 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 the concrete structure There was a disadvantage that it was not. There is also a disadvantage that increasing the amount of the water-repellent compound causes a decrease in concrete strength.

Furthermore, in the method of adding a drying shrinkage agent, it is possible to reduce the drying shrinkage of the concrete to prevent cracking of the concrete. However, there is no waterproofing effect of the concrete, and the invasion of moisture is prevented. There is a disadvantage that it is not enough to improve the durability of the concrete structure.

The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned drawbacks. As a result, it has been found that by mixing a specific organopolysiloxane with cement, the waterproofness of concrete can be increased without lowering the strength of concrete. The present invention was found to be able to reduce drying shrinkage as well as to achieve the present invention.

Accordingly, a first object of the present invention is to increase the waterproofness and reduce the drying shrinkage without lowering the strength of concrete, thereby preventing deterioration of concrete and improving the durability of concrete structures. An object of the present invention is to provide an excellent cement admixture. A second object of the present invention is to provide a cement admixture that has low drying shrinkage, has high waterproofness, and can construct a structure having excellent durability.

[0013]

The above objects of the present invention can be achieved by the following general formula (3):

Embedded image [Wherein, R is a monovalent hydrocarbon group having 1 to 20 carbon ^atoms, R 1, ^{R 2} and ^{R 3} is R or general formula (4)

[0014]

Embedded image ( Where a is 0, 1, 2, 3, or 4 ; b is an integer of 0 or more; c is an integer of 1 or more; R ⁴ is a hydrogen atom;
It is a monovalent hydrocarbon group or an acyl group having 1 to 15 carbon atoms. ), And m and n are 0 or a positive integer. The present invention has been attained 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) include, for example, methyl, ethyl, propyl,
Examples thereof include a butyl group, a pentyl group, a phenyl group, a 3,3,3-trifluoropropyl group, and R may be the same or different.

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

Embedded image

Embedded image

Embedded image

Embedded image Incidentally, in the polyoxyalkylene group, -CH ₂ CH ₂ O-
Group / —CH ₂ CH (CH ₃ ) O—
It is preferable that the ratio be 10 or more, because the waterproofness of the mixed concrete is reduced.

The polyoxyalkylene-modified organopolysiloxane used in the present invention is obtained by adding an organohydrogenpolysiloxane to a polyoxyalkylene having a double bond at a molecular terminal by a hydrogen atom bonded to silicon of the organohydrogenpolysiloxane. It can be easily obtained by adding it in an amount equal to or greater than the number of moles and subjecting it to 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 molecular weight of the polyoxyalkylene group is small, so that the water retention is poor and the drying shrinkage is large, which is not preferable. Moreover, the molecular weight is 30,0.
If it exceeds 00, it is disadvantageous in terms of manufacturing cost.

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

The above-mentioned addition reaction can be carried out at 30 to 200 ° C., but it is preferable to set the reaction temperature to 60 to 110 ° C., particularly from the viewpoint of rapidly proceeding the desired reaction. The reaction can be carried out without solvent, but ethanol, isopropanol, toluene,
The reaction can also be performed using a solvent such as THF, dioxane, ethyl acetate, and methyl ethyl ketone.

In general, concrete is obtained by mixing and hardening cement, water, aggregate and other additives used as required. The cement admixture of the present invention is added during the 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, high 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 aggregate include fine aggregates such as river sand, coarse aggregates such as river gravel, and lightweight aggregates such as crushed stones. Usually, the mixing ratio of bone and cement is 10
It is considered that 3000 parts by weight or less of the bone agent is good with respect to 0 parts by weight.

In the present invention, depending on the desired physical properties of the concrete, the additives include an AE agent (air entraining agent), a dispersant, a foaming agent, a coloring agent, a hardening agent, a setting retarder,
Chemical resistance agents, antifreeze agents, curing agents and the like can be added. Water is usually added to 100 parts by weight of cement.
It is preferable to add 0 to 80 parts by weight.

The cement mixture of the present invention comprises
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.
In particular, it is preferable to add 0.1 to 5 parts by weight. 0.0
If the addition is less than 5 parts by weight, it is not possible to obtain a cement mixture having sufficient waterproofness. If the addition is more than 10 parts by weight, the cost of the cement mixture is increased, which is uneconomical.

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

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

The method for hardening the cement composition using the admixture of the present invention is not particularly limited, and a conventional natural hardening method at room temperature or a condition under low temperature, high temperature, steam or water, as in the prior art. Any method can be employed as necessary, such as a curing method.

[0029]

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

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Embodiment 1 Synthesis of siloxane compound: average composition formula in a 1 liter flask equipped with a thermometer, stirrer and cooler is
Compound represented by

[0032]

Embedded image 206 g (0.89 mol), 173 g of ethanol and 2.5% by weight of a 0.6% solution of isopropanol chloroplatinate.
After charging 4 g, the mixture is heated and refluxed, and the siloxane compound represented by the average composition formula is represented by the following chemical formula (10).

[0033]

Embedded image 165 g (0.74 mol) was added dropwise over 2 hours to complete the reaction. Next, the obtained composition was heated at 80 ° C./3 mm
A siloxane compound having an average composition formula represented by the following chemical formula

Embedded image Was obtained in a yield of 80%. 25 of the obtained siloxane compound
The viscosity at 1 ° C. was 15.4 cs, the specific gravity was 0.947, and the refractive index was 1.4292.

Preparation of concrete test piece: After mixing ordinary Portland cement (referred to as cement) and silica sand at a weight ratio of 1: 3, the resulting mixture was mixed with the above-mentioned siloxane compound in an amount of 3.0 parts by weight based on 100 parts by weight of cement. Parts together with water to obtain a cement composition. The amount of water was added so that the flow value measured according to JISR5202 was 160 ± 2 mm.
The water / cement ratio at this time was 0.7.

Next, the obtained cement composition was subjected to 40 m
After molding into a rectangular parallelepiped of mx 40 mm x 160 mm, JI
SR5201 (physical test method for cement), JISA1
404 (Testing method for building cement waterproofing agent) and JIS
Curing was carried out in accordance with A1129 (mortar and concrete length change test) 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 JISR5201, a waterproof test according to JISA1404, 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 dry shrinkage in the table are values measured after 28 days from the preparation of the test piece, and the water absorption ratio is obtained by adding the increased weight of the test piece after immersion in water for 24 hours. Of the test piece (Comparative Example 5) in which no was used at all.

Embodiment 2 FIG. A compound represented by the average composition formula of the above (Chemical formula 9) is replaced with a compound represented by the average composition formula of the (Chemical formula 12).

Embedded image Except for replacing the above, a polyoxyalkylene-modified dimethylpolysiloxane was obtained in exactly the same manner as in Example 1. Using the obtained polyoxyalkylene-modified dimethylpolysiloxane, concrete test pieces were prepared and evaluated in exactly the same manner as in Example 1. The results are as shown in Table 1.

Embodiment 3 FIG. The compound represented by the average composition formula of the above (Chemical Formula 10)
Compound represented by the average composition formula of 3)

Embedded image Except for replacing the above, a polyoxypropylene-modified dimethylpolysiloxane was obtained in exactly the same manner as in Example 1. Using the obtained polyoxypropylene-modified dimethylpolysiloxane, concrete test pieces were 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, stirrer, and cooler has an average composition formula of
Compound represented by 4)

[0041]

Embedded image After charging 189 g (1 mol), 207 g of ethanol and 0.63 g of a 2.5% by weight isopropanol chloroplatinate solution, the mixture was heated to reflux and the average composition formula (Chem.
183 g (0.83 mol) of the siloxane compound represented by the formula (0) was added dropwise over 3 hours to terminate the reaction. Then, the obtained composition was distilled at 80 ° C./3 mmHg to distill off ethanol, and the siloxane compound of the average composition formula (Formula 15) was obtained.

[0042]

Embedded image Was obtained in a yield of 80%. 25 of the obtained siloxane compound
The viscosity at 2 ° C. was 20.6 cs, the specific gravity was 1.000, and the refractive index was 1.4372. Using the obtained siloxane compound, a concrete test piece was prepared in exactly the same manner as in Example 1 and evaluated. The results are as shown in Table 1.

Comparative Example 2 Concrete test pieces were 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 instead of the siloxane compound used in Example 1. The results are as shown in Table 1.

Comparative Example 3 Concrete test pieces were prepared and evaluated in exactly the same manner as in Example 1, except that the siloxane compound used in Example 1 was replaced with the polyoxyalkylene compound represented by the average composition formula (Formula 12). 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 an average composition formula (Formula 16)

Embedded image , Concrete specimens were 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 ──── ──────── 圧 縮 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 increases waterproofness and reduces drying shrinkage without lowering the compressive strength of concrete.

Continuing from the front page (72) Inventor Hiromi Osaki 28, Nishifukushima, Ojiku, Kushiro-mura, Nakakubijo-gun, Niigata 1 Shinsei Chemical Industry Co., Ltd., Synthetic Technology Research Institute (72) Inventor Masayoshi Tanaka Chiyoda-ku, Tokyo 2-6-1 Shin-Etsu Chemical Co., Ltd. (56) References JP-A-2-160651 (JP, A) Japanese Patent Publication No. 62-10947

Claims (3)

(57) [Claims] 1. A compound of the general formula (1) [Wherein, R is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ¹ , R ² and R ³ are R or a general formula (Chemical Formula 2). (In the formula, a is 0, 1, 2, 3, or 4 , b is an integer of 0 or more, c is an integer of 1 or more. R ⁴ is a hydrogen atom, a monovalent carbon atom having 1 to 15 carbon atoms.) A hydrogen group or an acyl group), and m and n are 0 or a positive integer. ] A cement admixture comprising an organopolysiloxane having at least one polyoxyalkylene group in one molecule represented by the following formula: 2. The method according to claim 1, wherein 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 wherein 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.