JP3289855B2 - Cement admixture and cement composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture and a cement composition mainly used in the civil engineering and construction industries.

[0002]

2. Description of the Related Art Cement is an indispensable material because it is inexpensive and can be used to construct large-scale structures. However, cement has the disadvantage of shrinking, and many cement expanders have been proposed for the purpose of preventing this shrinkage.

[0003] Cement expanders include lime-containing cement expanders that generate ettringite and Ca (OH) ₂ , which are expandable hydrates, metal powder cement expanders such as iron powder and aluminum powder, and magnesia cement. Lime-based cement expanders are mainly used in Japan because of their low cost and other factors.

Conventionally, CaO has been used as a lime-based cement expanding material.
Heat treating the source and SiO ₂ source, a free lime (f-CaO), f- CaO-C 3 S cement expansive to _{3CaO · SiO 2 (C 3 S} ) composed mainly of a cement minerals are known (Japanese Patent Publication No. 53-13650). However, when this cement expander is used for a mixed cement in which a pozzolanic substance is mixed, not only the amount of expansion is reduced, but also the expansion development is slowed, and the problem of adversely affecting dimensional stability and strength development is problematic. there were.

On the other hand, calcium aluminate is used alone or in combination with gypsum as a cement rapidly hardened material (Japanese Patent Publication No. 54-17771).

In recent years, due to the difficulty in securing on-site workers and the increase in large-scale construction, large amounts of thickeners and water-reducing agents have been mixed with fly ash and blast furnace slag for the purpose of labor-saving construction. Latent hydraulic substances such as were replaced with cement,
A concrete blending composition which does not require compaction or which can be compacted by microvibration has been proposed (Japanese Patent Laid-Open No. 3-45).
522, JP-A-3-237049, etc.). However, these concrete blend compositions have a problem that the shrinkage is large and the dimensional stability is poor.

The present inventor has made various efforts to solve the above-mentioned problems, and as a result, obtained the knowledge that the above-mentioned problems can be solved by using a specific cement admixture. Was.

[0008]

A resolution means for] That is, the present invention is blended CaO raw material and CaSO ₄ material, it was heat-treated, CaSO ₄ is, Ca
A cement admixture comprising an expanding material that is 10 to 50 parts by weight in a total of 100 parts by weight of O and CaSO ₄ and an amorphous calcium aluminate, a latent hydraulic substance, a thickener, and a water reducing agent. And a cement composition comprising the cement and the cement admixture.

Hereinafter, the present invention will be described in more detail.

The expanding material of the cement admixture according to the present invention is obtained by blending a CaO raw material and a CaSO ₄ raw material and heat-treating the mixture.
Total of 100 parts by weight of O and CaSO _4, CaSO ₄ is 10 to 50 parts by weight.

The raw material of the expanding material depends on the purity and cost.
Are those arbitrarily be selected, but are not particularly limited, for example, as a CaO material, such as CaCO ₃ quality or Ca (OH) ₂ the quality of such limestone or slaked lime, a CaSO ₄ material, anhydrous gypsum, Hemihydrate gypsum, dihydrate gypsum and the like can be mentioned. Impurities such as SiO ₂ , Fe ₂ O ₃ , CaF ₂ , MgO, and TiO ₂ present in the raw material are not particularly limited as long as the objects of the present invention are not substantially inhibited.

The compounding ratio of the CaO raw material and the CaSO ₄ raw material of the expanding material of the present invention is such that CaSO ₄ is 10 to 50 parts by weight based on the total of 100 parts by weight of the expanded material CaO and CaSO _4. It is preferable to mix them. If the content of CaSO ₄ is less than 10 parts by weight, for example, the material shows rapid expansion by one day, cracks may occur in a cement hardened body using the expanded material, and strength development may be reduced. If the amount of CaSO ₄ exceeds 50 parts by weight, the swellability tends to decrease.

In the present invention, the desulfurization decomposition temperature of gypsum varies greatly depending on the mixing ratio of the raw materials and the content of impurities. Therefore, the firing temperature during firing is not particularly limited. About 1,100 to 1,600 ° C is preferable.

The method of mixing the raw materials is not particularly limited, and a usual method can be used. The heat treatment method for producing the expanded material of the present invention is not particularly limited, and for example, any method such as firing by a rotary kiln or melting by an electric furnace is possible.

[0015] The particle size of the expansive substance is not particularly limited since it depends on the purpose and application of use.
The Brain value is preferably 1,500 to 8,000 cm ² / g. If it is less than 1,500, it may adversely affect the strength development and the fluidity of the cement composition. If it exceeds 8,000 cm ² / g, the expandability may not be sufficiently exhibited. The compounding ratio of the expansive substance varies depending on the purpose of use, and is not particularly limited. However, usually, a binder 100 composed of an expansive substance, an amorphous calcium aluminate, a latent hydraulic substance, and cement described below. The amount is preferably 3 to 12 parts by weight, more preferably 5 to 7 parts by weight with respect to parts by weight. If the amount is less than 3 parts by weight, the expandability is not sufficient, and if it exceeds 12 parts by weight, abnormal expansion may occur.

The amorphous calcium aluminate according to the present invention is obtained by melting a mixture of a CaO raw material and an Al ₂ O ₃ raw material and quenching the resulting clinker to obtain a pulverized clinker. Although the melting temperature of the raw material varies depending on impurities, it is usually 1,
500-1700C is preferred. Amorphous calcium aluminum
The CaO content of the glass is preferably 35 to 55% by weight. 35% by weight
If it is less than 5, the expandability may be insufficient, and if it exceeds 55% by weight, the fluidity of the cement composition using this amorphous calcium aluminate may be impaired, and the workability may be impaired. The fineness of the amorphous calcium aluminate varies depending on the purpose of use, and is not particularly limited. However, the Blaine value is preferably 2,000 or more. 2,000
If it is less than cm ² / g, the expandability may be reduced.

The amount of the amorphous calcium aluminate is preferably 10 to 100 parts by weight, more preferably 20 to 50 parts by weight, based on 100 parts by weight of the expanding substance. If the amount is less than 10 parts by weight, cracks tend to occur in the cured cement body using the same, and if it exceeds 100 parts by weight, the expandability tends to be insufficient. Also, the amount of the amorphous calcium aluminate is usually a swelling substance, amorphous calcium aluminate,
Binder consisting of latent hydraulic substance and cement described below
3 to 7 parts by weight is preferable for 100 parts by weight. When the amount is less than 3 parts by weight, the time of the onset of swelling is delayed, and abnormal swelling may occur.
Workability may be adversely affected.

The latent hydraulic material according to the present invention, when used in combination with cement, improves fluidity, resistance to material separation, and solidity, and specifically includes silica fume and fly. Ash and pozzolanic substances such as blast furnace slag fine powder. The fineness of the latent hydraulic substance is not particularly limited, but may be expressed in terms of Blaine value.
It is preferably 4,000 cm ² / g or more. If it is less than 4,000 cm ² / g, fluidity and resistance to material separation may be insufficient. The amount of latent hydraulic material used is a total of 10
The amount is preferably 10 to 70 parts by weight with respect to 0 parts by weight. If the amount is less than 10 parts by weight, the fluidity and the material separation resistance of the cement composition are not sufficient, and if it exceeds 70 parts by weight, the fluidity tends to be extremely reduced.

Here, as cement, ordinary, early strength,
Various types of Portland cement, alumina cement, and the like having an ultra-high strength and moderate heat can be used.

The thickener according to the present invention is used for maintaining fluidity and for suppressing material separation, and specifically includes methylcellulose, polyethylene glycol and the like.
Water-soluble polymer thickeners such as acryl-based, ethylene oxide-based, and polyacrylamide-based, and polyvinyl alcohol-based, etc., but are already commercially available as insoluble admixtures in water. It is also possible to use

As the water-insoluble separable admixture, for example, as methylcellulose, "ASKACLEAN" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), "AQUASETTER" (trade name, manufactured by Takemoto Yushi Co., Ltd.), and Electrochemical The trade name is "Dencastabicon A" manufactured by Kogyo Co., Ltd., and the acrylic type is "Siebeta" manufactured by Sankyo Kasei Kogyo Co., Ltd., and "Alonsi Creat W" manufactured by Toa Gosei Chemical Co., Ltd. Is mentioned.

The amount of the thickener used may be the specified amount of the manufacturer, but usually 1 m ^{3 of} concrete.
It is preferably about 0.01 to 2 kg per unit, and it is preferable to appropriately change the amount to be used depending on the purpose and use situation.

Although the water reducing agent according to the present invention is not particularly limited, it is preferable to use a high performance water reducing agent, a high performance AE water reducing agent, a fluidizing agent and the like. High performance water reducing agent, high performance A
E The water reducing agent and the superplasticizer are roughly classified into naphthalene-based,
It is classified into melamine type, polycarboxylic acid type, aminosulfonic acid type and the like. Representative examples include naphthalene-based products such as Kao Corporation's product name `` Mighty 2000WH '' and Denka Chemical Industries' product names `` Denka FT-500 '' and `` Denka FT-80 ''. Showa Denko brand name "Melment F-10"
00H "and the like, and polycarboxylic acid-based products such as" Darex Super-100PHX "and" Darex Super 200 "manufactured by Denkagreth, and" Reobuild SP-8HS "manufactured by NMB And the like. Aminosulfonic acid-based product name “Palic FP-10” manufactured by Fujisawa Pharmaceutical Co., Ltd.
0U "and the like. In addition, ZEON Corporation, Kobe Materials, Sanyo Kokusaku Pulp, Takemoto Yushi, Fukui Chemical Industries,
The same water reducing agent is commercially available from various companies such as Daiichi Kogyo Seiyaku and other companies. The amount of these water reducing agents used is sufficient within the range specified by the manufacturer, but naphthalene-based and melamine-based
1 to 4 parts by weight, and 1 to 2 parts by weight of a polycarboxylic acid or aminosulfonic acid based on 100 parts by weight of a cement, a latent hydraulic substance, an expanding substance, and a binder comprising amorphous calcium aluminate Although preferred, there is no particular limitation.

[0024] The cement admixture of the present invention comprises an expanding material, an amorphous calcium aluminate, a latent hydraulic material, a thickener, and a water reducing agent as main components to impart effective expandability. By combining the expanding material with amorphous calcium aluminate, the free
It prevents CaO from being consumed by the pozzolanic substance and reduces the amount of swelling, and prevents the time of strength development from being delayed.By coexisting with amorphous calcium aluminate, ettringite is effectively produced. It is to let.

Also, the mixing ratio of the CaO raw material and the CaSO ₄ raw material,
By adjusting the mixing ratio of the expanding material and calcium aluminate, it is possible to adjust the expansion amount and expansion time of the cement admixture according to the type of cement used.

The particle size of the cement admixture of the present invention depends on the purpose and use of the cement admixture, and is not particularly limited. Usually, however, the Brain value is preferably from 1,500 to 8,000 cm ² / g. 1,500cm ² / g
If less than 8,000 c
If it exceeds m ² / g, the expandability may not be sufficiently exhibited. The amount of the cement admixture varies depending on the purpose of use, but is usually preferably 3 to 15 parts by weight, more preferably 5 to 10 parts by weight, per 100 parts by weight of cement. If the amount is less than 3 parts by weight, the expandability is not sufficient. If the amount exceeds 12 parts by weight, abnormal expansion may occur.

The amount of water used in the present invention is not particularly limited, and can be the amount used in ordinary mortar or concrete.

In the present invention, in addition to the cement admixture, aggregates such as sand and gravel, setting retarders, cement hardened materials, rust preventives, antifreezes, polymer emulsions, clay minerals such as bentonite and montmorillonite, Ion exchangers such as zeolite, hydrotalcite, and hydrocalumite,
Inorganic sulfates such as aluminum sulfate and sodium sulfate,
One or two or more selected from the group consisting of inorganic phosphates and boric acid can be used in combination within a range that does not substantially inhibit the object of the present invention.

The method of mixing and kneading the cement admixture and the cement composition of the present invention is not particularly limited, and ordinary methods are sufficient. As a mixing device for the cement admixture and cement of the present invention, an existing stirring device can be used. For example, a tilting mixer, an omni mixer, V
Type mixers, Henschel mixers, Nauta mixers and the like are available. In addition, for mixing, the respective materials may be mixed at the time of construction, or some or all may be mixed in advance. Curing method of the cement hardened body using the cement admixture of the present invention is not particularly limited, and generally performed, any method such as room temperature / normal pressure curing, steam curing, high temperature / high pressure, and pressure curing, etc. Can be used.

[0030]

The present invention will be described below in detail with reference to examples.

Example 1 A CaO raw material and a CaSO ₄ raw material were blended so that the ratio of CaCO ₃ and CaSO _{4 in} the product became a predetermined ratio, and calcined at 1,400 ° C. using a rotary kiln to remove clinker as an expanding material. It was prepared and pulverized to a Blaine value of 3,000 ± 200 cm ² / g to prepare an expanded material. The weight ratio between CaO and CaSO ₄ of the expanding material was determined from the chemical analysis values. CaSO ₄ is converted from the SO ₃ value of the chemical analysis, and CaO is a value obtained by subtracting CaO in CaSO ₄ from total CaO. Also, the CaO raw material and the Al ₂ O ₃ raw material were blended, and the mixture was melted at 1,650 ° C. in an electric furnace and quenched. CA). For a total of 100 parts by weight of cement and latent hydraulic substance, 30 parts by weight of latent hydraulic substance, 100 parts by weight of binder consisting of cement, expandable substance, amorphous calcium aluminate, and latent hydraulic substance On the other hand, using 7 parts by weight of the swelling substance and 5 parts by weight of amorphous calcium aluminate, the unit amount of the binder in the concrete was 460 kg / m ^3, and the unit amount of the other materials was water.
158.1 kg / m ³ , fine aggregate 889 kg / m ³ , coarse aggregate 741 kg / m ³ , thickener
A concrete containing 20 g / m ³ , a water reducing agent 6.9 kg / m ³ , and an AE agent 23 g / m ³ was prepared. The expansion rate of this concrete and the slump flow value and VF value which are indicators of fluidity were measured.
The results are also shown in Table 1.

<Materials Used> CaO raw material: CaCO ₃ , Limestone CaSO _{4 from} Aomi mine of Denki Kagaku Kogyo Co., Ltd. Raw material: anhydrous gypsum by-produced hydrofluoric acid Al ₂ O ₃ Raw material: commercial bauxite Expanding substance a: CaSO _{4 in} expanding substance Swelling substance b: CaSO ₄ in the swelling substance 30% by weight Swelling substance c: CaSO ₄ in the swelling substance 50% by weight Swelling substance d: CaSO _{4 in the} swelling substance 60% by weight Swelling substance e: 100% by weight of CaO in expansive material Commercial product α: Onoda Cement Co., Ltd.
Brain value: 3,100 cm ² / g Commercial product β: Expandable material trade name “CSA # 20” manufactured by Denki Kagaku Kogyo Co., Ltd. Brain value: 2,950 cm ² / g A-CA: CaO content 40% by weight, Brain Value 3,120cm ² /
g Latent hydraulic substance A: Fly ash manufactured by Tohoku Electric Power Industry Co., Ltd. Thickener: Methylcellulose manufactured by Shin-Etsu Chemical Co., Ltd. Water reducer: Denkagreth Co., Ltd. product name "DAREX SUPER-100PHX", main component polycarboxyl Acid-based AE agent: Denka Grace Co., Ltd. product name "AEA-S", main component sulfonic acid hydrocarbon-based cement: Denki Kagaku Kogyo Co., Ltd. ordinary Portland cement Fine aggregate: Himekawa, Niigata, specific gravity 2.63, FM 2.74 Coarse aggregate: from Himekawa, Niigata Prefecture, specific gravity 2.67, FM6.94 water: tap water

<Test Method> Expansion coefficient: Measured according to JIS A 6202 (Method B). Slump flow value: Underwater non-separable concrete manual, Appendix 1, "Test of non-separable concrete underwater, Slump flow test" issued by the Foundation, Coastal Development Technology Center and Research Institute for Fishing Villages and Fishing Villages The spread of the concrete was measured at two points in the direction perpendicular to the above. VF value: V.V. F. Using a consistency meter, the cement composition was allowed to flow out of the hole at the bottom of the cylinder without vibration, and the drop of the top surface of the cement composition in the cylindrical container at the time when the flow stopped was measured and defined as the VF value. . Filling property: Judgment was made on the filling property of the concrete without vibration. In a transparent acrylic container with a plane cross section of 50 x 50 cm and a height of 40 cm, a total of 16 mm φ rebars are set vertically and horizontally at a pitch of 50 mm. 56 bars are arranged, and a space is provided on one side of the container where no bars are arranged, and this space is filled with concrete. ◎ was determined. × indicates that the filling was completed within 15 seconds or more, は indicates that the filling was completed within 10 seconds, and ◎ indicates that the filling was completed within 7 seconds.

[0034]

[Table 1]

Example 2 The amount of the swelling substance b was changed as shown in Table 2 with respect to 100 parts by weight of the binder composed of cement, latent hydraulic substance, swelling substance and amorphous calcium aluminate. Other than that, it carried out similarly to Example 1. The results are also shown in Table 2.

[0036]

[Table 2]

Example 3 Using the expanding material b, 100 parts by weight of a binder composed of cement, a latent hydraulic material, an expanding material, and amorphous calcium aluminate were mixed with amorphous calcium aluminate. The procedure was performed in the same manner as in Example 1 except that the type and amount were changed as shown in Table 3. The results are also shown in Table 3.

<Materials used> A-CARO: CaO content 35% by weight, Brain value 3,150 cm ² /
g A-CAha: CaO content 45% by weight, Brain value 3,090cm ² /
g

[0039]

[Table 3]

Example 4 Using the intumescent substance b, a total of 10 pieces of cement and latent hydraulic substance were used.
As shown in Table 4, the procedure was performed in the same manner as in Example 1 except that the type and amount of the latent hydraulic substance were changed with respect to 0 parts by weight. The results are also shown in Table 4.

<Materials used> Latent hydraulic substance B: blast furnace slag, Brain value 4,200 cm ² / g

[0042]

[Table 4]

[0043]

By using the cement admixture of the present invention, a compaction-free concrete excellent in dimensional stability and strength development can be obtained.

Continuation of front page (56) References JP-A-49-78731 (JP, A) JP-A-48-78228 (JP, A) JP-A-54-43935 (JP, A) JP-A-48-1024 (JP, A) JP-A-51-37121 (JP, A) JP-A-58-49651 (JP, A) JP-A-49-33924 (JP, A) JP-A-7-232944 (JP, A) JP-A-57-156352 (JP, A) JP-B-50-13816 (JP, B1) JP-B-52-41285 (JP, B1) JP-B-48-9448 (JP, A) B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 22/06-22/16

Claims (2)

(57) [Claims] 1. A CaO raw material and a CaSO ₄ raw material are blended and heat-treated.
It becomes Te, CaSO ₄ is, in total 100 parts by weight of CaO and CaSO ₄ 10 to 50
A part by weight of a swelling substance and an amorphous calcium aluminum
G, a latent hydraulic material, a thickener, and a water reducing agent. 2. A cement composition comprising cement and the cement admixture according to claim 1.