JPH05330880A - Cement admixture and cement composition - Google Patents

Abstract

PURPOSE:To provide a cement admixture and a cement compsn. which can give excellent water proofing property and high durability to a concrete or mortar structure. CONSTITUTION:The cement admixture contains organopolysiloxane expressed by the general formula R<1>aR<2>bXcSiO(4-a-b-c)/2 by 1-500 pts.wt. to 100 pts.wt. of powdery or short fiber inorg. material. In the formula, R<1> is a univalent hydrocarbon group or 1-20C, R<2> is an atom or group selected among H, OH, OR<3>, wherein R<3> is a univalent hydrocarbon group of 1-3C and X is OM, wherein M is an alkali metal or alkaline earth metal, and (a), (b) and (c) satisfy 0<a<3, 0<b<=3, 0<c<=3, 0<a+b+c<=3. The cement compsn. contains 0.1-30 pts.wt. of this cement admixture to 100 pts.wt. of cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture and a cement composition which prevent water from penetrating to impart high durability to concrete or mortar structures.

[0002]

2. Description of the Related Art In recent years, a building structure using concrete or mortar has been regarded as a problem of deterioration due to salt damage, acid rain, freezing damage, rusting of reinforcing bars and the like. The deterioration of the durability of a building structure is caused by the penetration of moisture into the structure. For example, salt damage occurs when water containing chloride ions penetrates into the main structure. If acid rain penetrates into the structure, it becomes brittle even if the main structure is neutralized. There is a risk that the reinforcing bars will rust, and if they do, strength deterioration will occur. Even if it is not chloride ion or acid rain, frost damage occurs if water penetrates into the main structure. If water freezes, the expansion distorts the shape of the building structure, and if it distorts, it causes deformation and cracks and weakens the strength. In order to solve these problems, it is necessary to suppress the permeation of water into the structure.

There are some proposals as measures for preventing deterioration of concrete or mortar structures. In order to prevent the penetration of moisture from the outside, for example, a method of applying a waterproofing agent to the surface of a structure is already known. In addition, JP-A 1-160886
Japanese Patent Application Laid-Open No. 2-16186 and Japanese Patent Application Laid-Open No. 2-16186 propose a method of applying a specific alkoxysilane and an alkylalkoxysilane to the surface of a structure and preventing the deterioration of the concrete structure by impregnating the surface of the structure. .. Japanese Unexamined Patent Publication No. 2-150477 proposes a method of applying a specific organopolysiloxane.

The conventional method of applying and impregnating a specific waterproof and water-repellent material forms an extremely thin waterproof layer on the surface of concrete or mortar structure. Such a waterproof layer is not durable and loses function over time.

In contrast to the method of forming a waterproof layer on the surface, a method of adding a water repellent compound to a cement composition is also known. Japanese Examined Patent Publication No. 44-13037 proposes to add an alkylalkoxysilane to a cement composition. Japanese Patent Application Laid-Open No. 2-160651 proposes to add an organopolysiloxane containing a specific hydrolyzable group. JP-A-58-2252 also proposes to add an organopolysiloxane.

Even if the water-repellent compound is added to the inside of the structure as it is, it is basically not an essential solution. Conventional water-repellent compounds lose their water repellency relatively easily when exposed outdoors in a cement structure. If the amount of addition is increased to a level sufficient to maintain the water repellency for a long time, the structure obtained by molding has a drawback that the strength is remarkably reduced.

Conventional water-repellent compounds also have problems when kneaded in cement compositions. Water-repellent compounds have poor hydrophilicity and poor dispersibility in water. Therefore, it is very difficult to uniformly knead the cement composition.

Several water-repellent compounds are known in addition to the above. Japanese Examined Patent Publication No. 36-5379 discloses a method for adding a silicic acid fine powder treated with organohalosilane to a cement composition. Japanese Unexamined Patent Publication No. 2-275742 proposes to add silica fine powder treated with silicone oil to a cement composition. All of these have the drawback that when they are actually carried out, they cause a significant decrease in strength in the cement structure.

[0009]

The present invention has been made to solve the above problems, and is a cement admixture and a cement composition capable of imparting excellent waterproofness and high durability to concrete and mortar structures. The purpose is to provide goods.

[0010]

The cement admixture of the present invention, which has been made to achieve the above object, has the general formula (A) R ¹ _a R ² _b X _c SiO _{(4-abc) / 2} ... The amount of the organopolysiloxane represented by A is 1 to 50 parts by weight based on 100 parts by weight of the powdery or short fiber inorganic material.
It is contained in a proportion of 0 parts by weight. R ¹ in the formula (A) is a monovalent hydrocarbon group having 1 to 20 carbon atoms. However, this hydrocarbon group may or may not be further substituted with a derivative group other than the hydrocarbon group. R ² is-
H, -OH, an atom or a group selected from among -OR ^3. R ³ is a monovalent hydrocarbon group having 1 to ³ carbon atoms. X is a group represented by -OM. However, this M is an alkali metal or an alcal earth metal. a is 0 <a
<3 and b are represented by 0 ≦ b ≦ 3, c is represented by 0 <c ≦ 3, and a + b + c is represented by 0 <a + b + c ≦ 3.

The cement composition of the present invention contains such a cement admixture in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of cement.

The general formula (A), which represents the structure of the organopolysiloxane, is specifically

[0013]

[Chemical 1]

[0014]

[Chemical 2]

[0015]

[Chemical 3]

Etc. are represented.

The hydrocarbon group directly bonded to the silicon atom may further have a derivative group. Examples of such a derivative group include a phenyl group, CH ₂ ═CH ₂ —, and F ₃ C ₃
H ₄ − and the like can be mentioned.

Such an organopolysiloxane can be obtained by heating an organocyclopolysiloxane with a strong alkali hydroxide to cause a ring-opening reaction.

In the present invention, an inorganic material is used together with such an organopolysiloxane. As the inorganic material in this case, a powdery or short fiber inorganic material can be used. Specific examples include silica, alumina, silica fume, fly ash, blast furnace slag, cement, silica sand, calcium carbonate, carbon, glass fiber and the like. These may be used alone or in combination.

It is preferable that the organopolysiloxane and the inorganic material are in a mixed state with each other, and the mixing ratio thereof is, as a general rule, appropriately determined according to the use of the end use product. Usually, the organopolysiloxane may be 1 to 500 parts by weight with respect to 100 parts by weight of the inorganic material. If the amount of the organopolysiloxane is less than 1 part by weight, the waterproof property will not be sufficiently exhibited, and if it exceeds 500 parts by weight, there will be no effect depending on the ratio, and it is uneconomical.

No matter what method is used for mixing the two, there is no particular problem. For example, the organopolysiloxane may be impregnated into the inorganic material by stirring and mixing the organopolysiloxane with the inorganic material as it is or in a solution state. In such a case, specifically, a method of charging an inorganic material into a machine capable of high-speed stirring and slowly dropping or spraying the organopolysiloxane itself or a diluted solution thereof while stirring is used. It is also possible to use equipment such as fluidized beds. When a diluting solution of organopolysiloxane is used, the solvent may be an organic solvent such as benzene, toluene, xylene, or an aqueous alkali solution.

The cement composition of the present invention contains the admixture as described above and cement. As the cement, ordinary Portland cement, moderate heat Portland cement, early strength Portland cement, low heat Portland cement,
Examples include sulfate-resistant Portland cement, blast furnace cement, alumina cement, silica cement, fly ash cement, and the like. These may be used alone,
It may be combined and used in a mixture. It may be appropriately selected depending on the end use product.

In addition to these, the above-mentioned cement composition is usually admixed with aggregate, water, and optionally other mixing components.

Examples of aggregates include crushed aggregates such as river sand, river gravel, and crushed stones or coarse aggregates, as well as lightweight aggregates for lightweight concrete or mortar. These are widely used in ordinary cement compositions and can be used in the present invention as well.

Water is used in addition to the aggregate. Ice may actually be added. As additives other than water, for example, AE agents (air entraining agents), dispersants, foaming agents,
Coloring agents, rapid hardening agents, setting retarders, chemical resistant agents, antifreezing agents, curing agents and the like can be mentioned.

In the cement composition of the present invention, each of the above components may be in a mixed state. The mixing ratio is 0.1 to 30 parts by weight of a cement admixture with respect to 100 parts by weight of cement,
Preferably 0.5 to 15 parts by weight is desirable. If the proportion of the cement admixture is less than 0.1 parts by weight, the waterproof property is not sufficiently exhibited, which is not preferable.

The amount of the aggregate mixed is preferably 3000 parts by weight or less with respect to 100 parts by weight of cement. The mixing ratio of water and other additives may be appropriately selected depending on the properties of the additive itself, the end use product, and the like. The mixing ratio of water is often 20 to 80 parts by weight with respect to 100 parts by weight of cement. The amounts of the other additives may be appropriately determined depending on the intended use of the final product within the range that does not impair the object of the present invention.

The method of mixing the cement composition is usually of little concern. The cement and the cement mixture may be mixed, and the resulting mixture may be mixed with water, aggregate, or the like.
The cement admixture may be dissolved in water in advance and the cement or aggregate may be mixed therein. A mixer may be used for mixing.

The cement composition containing water becomes a slurry. Pour into mold or apply, impregnate on other materials,
It can be sprayed and molded. These will solidify if left at room temperature. You may solidify under conditions, such as low temperature, high temperature heating, steam, and water, as needed. The curing method does not matter.

[0030]

EXAMPLES Examples of the present invention will be described below. Example 1 5 parts by weight of potassium hydroxide and 95 parts by weight of octamethylcyclotetrasiloxane were heated in a flask at about 140 ° C. for 5 hours under nitrogen bubbling. Viscosity about 3500 cP
s, and a liquid organopolysiloxane (CH ₃ ) ₂ (KO) _1/2 SiO _{3/4 in} which potassium oxide (—OK) groups were bonded to both ends of the siloxane chain was obtained.

Silica fume (manufactured by Elchem Co.) and the aforementioned organopolysiloxane were placed in a mixer and mixed for 1 hour to obtain a cement admixture. The mixing ratio was silica fume / organopolysiloxane = 2/1. The above cement admixture obtained was mixed with ordinary Portland cement. The mixing amount of the cement admixture was 3.0 parts by weight with respect to 100 parts by weight of cement. Furthermore, silica sand in an amount three times that of ordinary Portland cement was added and mixed, and thereafter, water and water were continuously mixed. Addition of water is JI
It was measured according to SR5201 and stopped at the point where the flow value of the mixture was 160 ± 2 mm. The cement composition, which became a slurry by adding water, has a size of 40 mm.
It was molded into × 40 mm × 160 mm and cured according to JISR5201 (physical test method for cement) and JISA1404 (test method for cement waterproofing agent for construction) to obtain a test body.

Regarding the obtained test body, JISR5201
According to JIS A1404, a water absorption test was conducted. The results are shown in Table 1. It was found that the test piece was excellent in strength reduction and waterproofness.

Examples 2 to 5 The same procedure as in Example 1 was carried out, except that the mixing ratio of organopolysiloxane and silica fume was changed as shown in Table 1. The results are shown in Table 1. It was found that the test body was excellent in strength and waterproofness.

Examples 6-8 Same as Example 1, but instead of using silica fume, the other inorganic materials shown in Table 1 were used. The mixing ratio was also as shown in Table 1. Table 1 also shows the test results together with the mixing ratio of the inorganic materials. It was found that the test body had excellent compressive strength and waterproofness.

Comparative Example 1 Same as Example 1 but without cement admixture. The results are shown in Table 1. It was found that the test body had a large amount of water absorption and lacked waterproofness.

Comparative Examples 2 and 3 Same as Example 1, but using organopolysiloxane as an additive instead of using the cement admixture mixed with inorganic material. The results are shown in Table 1. It was found that the test body had a large amount of water absorption and a low compressive strength.

[0037]

[Table 1]

In the table, the mixing ratio is a value of a / b in which the weight of the organopolysiloxane in the cement admixture is a and the weight of the inorganic material is b. Addition amount of cement is 100
It is a relative weight value in parts by weight. The compressive strength was confirmed after exposure to the atmosphere for 28 days. The unit is Kgf / cm ² .
The water absorption ratio was compared by setting the water absorption amount of Comparative Example 1 to 1.

[0039]

INDUSTRIAL APPLICABILITY The cement admixture of the present invention or the cement composition in which it is mixed can provide a structure having excellent waterproofness and high durability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Endo, 28, Nishi-Fukushima, Kubiki-mura, Nakakubiki-gun, Niigata Prefecture 1 Shinetsu Chemical Industry Co., Ltd. Synthetic Technology Laboratory 1 at 28, Nishifukushima, Kubiki-mura, Shin-Etsu Chemical Co., Ltd. Synthetic Technology Laboratory (72) Inventor Masayoshi Tanaka 2-6-1, Otemachi, Chiyoda-ku, Tokyo Shin-Etsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A compound represented by the general formula (A) R ¹ _a R ² _b X _c SiO _{(4-abc) / 2} ... A (R ¹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ² is −
An atom or a group selected from H, —OH, and —OR ³ (R ³ is a monovalent hydrocarbon group having 1 to ³ carbon atoms), and X is —O.
A group represented by M (M is an alkali metal or an alkaline earth metal), a is 0 <a <3, b is 0 ≦ b ≦ 3, and c is 0 <c
≦ 3, a + b + c is 0 <a + b + c ≦ 3), and the organopolysiloxane is contained at a ratio of 1 to 500 parts by weight to 100 parts by weight of the powdery or short fiber inorganic material. And cement admixture. 2. General formula (A) R ¹ _a R ² _b X _c SiO _{(4-abc) / 2} ... A (R ¹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R ² is −
An atom or a group selected from H, —OH, and —OR ³ (R ³ is a monovalent hydrocarbon group having 1 to ³ carbon atoms), and X is —O.
A group represented by M (M is an alkali metal or an alkaline earth metal), a is 0 <a <3, b is 0 ≦ b ≦ 3, and c is 0 <c
≦ 3, a + b + c is 0 <a + b + c ≦ 3), and the organopolysiloxane represented by 0 <a + b + c ≦ 3) is contained in the cement admixture in an amount of 1 to 500 parts by weight based on 100 parts by weight of a powdery or short fiber inorganic material. A cement composition comprising 0.1 to 30 parts by weight with respect to 100 parts by weight of cement.