JP2001247349A - Cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement composition excellent in workability, capable of developing high initial strength and capable of imparting set cement with a small dimensional change. SOLUTION: This cement composition comprises (A) a hydraulic composition which comprises a burned product obtained from one or more kinds of raw materials selected from burned ash of municipal refuse and burned ash of sewage sludge and comprising 10-40 wt.% of 11CaO.7Al2O3.CaCl2 and one or more kinds selected from 3CaO.SiO2, and 2CaO.SiO2, and gypsum, (B) blast-furnace slag and (C) slaked lime. A method for producing set cement comprises casting and curing slurry obtained by kneading the above cement composition with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition which is excellent in workability and has a large initial strength, and a method for producing a hardened cement body using the same.

[0002]

2. Description of the Related Art Conventionally, as cement used for producing cement-based building materials, ordinary cement, early-strength cement, slag cement, and the like have been used. Measures have been taken to increase the strength expression by autoclaving to increase the productivity. However, when steam curing or autoclave treatment is performed, if the strength of the molded body is not sufficient, there is a problem that explosion or cracks occur in the molded body. On the other hand, for cement-based building materials, a cement hardened body using an environmentally conscious cement (eco-cement) using municipal waste incineration ash or sewage sludge incineration ash as a cement material has been proposed (JP-A-11-228196, etc.). ). Such an eco-cement has a feature that it has a rapid setting and a large initial strength expression, but has poor fluidity when formed into a slurry, and has a problem in workability. There were problems such as large dimensional changes, and it was difficult to use as a building material.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cement composition which is excellent in workability and has a large initial strength.

[0004]

Under these circumstances, the present inventors have conducted intensive studies and as a result, have found that a hydraulic composition having a specific composition made from incinerated ash from municipal waste or ash from sewage sludge, a blast furnace slag and By using slaked lime, workability is excellent,
The present inventors have found that a cement composition having a large initial strength development and a small dimensional change after curing can be obtained, and completed the present invention.

[0005] That is, the present invention provides (A) a hydraulic composition containing a calcined product obtained from at least one selected from municipal waste incineration ash and sewage sludge incineration ash, comprising C ₁₁ A ₇ Ca
Contains a calcined product containing 10 to 40% by weight of Cl ₂ and at least one selected from C ₃ S and C ₂ S, a hydraulic composition containing gypsum, (B) blast furnace slag, and (C) slaked lime. To provide a cement composition.

The present invention also provides a method for producing a hardened cement, characterized in that a slurry obtained by kneading the cement composition and water is formed and cured.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The hydraulic composition (A) used in the present invention is selected from municipal waste incineration ash and sewage sludge incineration ash.
Includes fired products made from seeds or more. Also, the hydraulic composition is one comprising a a C ₁₁ A ₇ CaCl ₂ 10~40 wt%, the calcined product contains at least one element selected from C ₃ S and C ₂ S, and gypsum. Such a hydraulic composition may be prepared for this purpose. For example, an environment-friendly hydraulic composition described in JP-A-7-165446,
It is also possible to use a quick-setting type mixed cement described in 7-165447. In particular, the use of fired materials such as incinerated ash from city refuse and ash from sewage sludge can reduce the cost of cement itself and is also preferable from the viewpoint of effective utilization of resources.

[0008] Gypsum to be mixed with the hydraulic composition includes:
The form is not particularly limited, for example, dihydrate gypsum, α-type or β-type hemihydrate gypsum, type III anhydrous gypsum, type II anhydrous gypsum and the like, and these can be used alone or in combination of two or more types . The mixing amount of these gypsums is not particularly limited, but the molar ratio (SO ₃₎ to Al ₂ O ₃ in the hydraulic composition is
/ Al ₂ O ₃ ) in the range of 0.4 to ₃ , especially 0.5 to 2. Note that, depending on the cement raw material, the gypsum may already be contained in the hydraulic composition, but in such a case, the amount of gypsum may be adjusted so that the molar ratio is as described above.

The blast furnace slag (B) used in the present invention has an action as an aggregate and improves workability, and has a brain specific surface area of 3000 to 5000 cm ² / g, JIS.
Those having a basicity of 1.4 or more specified in R5211 are preferred.

The slaked lime (C) used in the present invention promotes the hydraulic properties of the blast furnace slag and contributes to the development of strength.

The cement composition of the present invention can further contain (D) silica fume, which can increase the strength and durability of the cured cement. Silica fume is a fine powder containing silica as a main component by-produced when producing silicon, a silicon-containing alloy, zirconia, or the like.

The compounding amount of each component in the cement composition of the present invention is based on the total amount of the components (A), (B), (C) and (D) being 100 parts by weight. ) Is preferably from 30 to 60 parts by weight, particularly preferably from 30 to 50 parts by weight, and component (B) is 2 parts by weight.
0 to 65 parts by weight, preferably 30 to 65 parts by weight, component (C) is preferably 1 to 10 parts by weight, particularly 5 to 10 parts by weight, and component (D) is 0 to 15 parts by weight, particularly 5 to 10 parts by weight. It is preferably in parts by weight. In the present invention, the hydraulic composition and slaked lime are used as the calcareous raw materials, and silica fume is used as necessary in the blast furnace slag as the siliceous raw material, so that the ratio of the total calcareous raw material and the siliceous raw material is balanced. It is preferable to adjust the amount of slaked lime or silica fume within the above range, and the weight ratio of the hydraulic composition / blast furnace slag is in the range of 0.5 to 2.0,
The curing strength and the fluidity of the raw material mixture necessary for handling of the raw plate are sufficiently satisfactory, and thus are preferable. Further, in order to more preferably exert the strength of the product, a cement mixture 85 having a weight ratio of hydraulic composition / blast furnace slag in the range of 0.8 to 1.2 is used.
It is preferable to mix 1 to 10 parts by weight of slaked lime and 0 to 15 parts by weight of silica fume to 95 parts by weight.

The cement composition of the present invention may further contain reinforcing fibers, for example, organic fibers, inorganic fibers,
Pulp or the like is used. As organic fiber, vinylon,
Acrylic, polypropylene, aramid fibers and the like can be mentioned; inorganic fibers include carbon, glass fibers, wollastonite needle crystals and the like. These fiber lengths are preferably from 4 to 20 mm. These fibers are
It is preferable to add 1 to 5 parts by weight, particularly 1 to 3 parts by weight, based on 100 parts by weight of the total of the components (A) to (D), since sufficient strength can be obtained. In addition, examples of the pulp include virgin pulp and waste paper pulp, and pulp that has been subjected to wet crushing, dry crushing, or the like can be used. Pulp is 1 to 5 parts by weight based on 100 parts by weight of the total of the components (A) to (D),
In particular, it is preferable to add 1 to 4 parts by weight because sufficient strength can be obtained.

The cement composition of the present invention may further contain various admixtures, for example, a thickener, a water reducing agent, a slurry fluidizer, a slurry viscosity modifier, a dispersant, and a foaming agent. Among them, examples of the thickener include methyl cellulose, polyethylene oxide, polyvinyl alcohol, carboxymethyl cellulose, and the like, and 0.1 to 0.3 based on 100 parts by weight of the components (A) to (D) in total.
It is preferable to add 0.1 parts by weight, particularly 0.1 to 0.2 parts by weight, since an appropriate viscosity is obtained and the dispersibility of the reinforcing fiber becomes good. Examples of the water reducing agent include naphthalene / sulfonic acid type, carboxylic acid type and the like, and the components (A) to
1 to 3 parts by weight, especially 1 to 100 parts by weight of (D)
It is preferable to add 2 parts by weight in terms of dispersibility and strength.

In order to produce a hardened cement using the cement composition of the present invention, first, the cement composition and water are kneaded to prepare a slurry. The amount of water is appropriately determined in consideration of the specific gravity, strength, and other physical properties of the obtained cement hardened product. For example, 20 to 70 parts by weight, particularly 30 to 65 parts by weight based on 100 parts by weight of the cement composition It is preferred that

As a method of preparing a slurry using these components, for example, (1) a method of simultaneously kneading and preparing a cement composition and water, and (2) a blast furnace slag and / or silica fume are previously treated with water. A method of kneading and preparing a processed material and other components is exemplified. Particularly, the slurry prepared by the method (2) is preferable because the dimensional change of the obtained cured product is smaller. Here, in the method (2), as a water treatment method for the blast furnace slag and / or silica fume, a method of spraying water on the blast furnace slag and / or silica fume, and mixing the blast furnace slag and / or silica fume with water. Method, wet crushing of blast furnace slag and / or silica fume, method of mixing blast furnace slag and / or silica fume with water and filler material (Japanese Patent Application No.
No. -68240), and any of these may be used as long as the processed material is in a water-containing state such as a slurry or wet state. Further, the treated product thus obtained is stabilized by leaving it for 30 minutes or more, and the dimensional change of the cured product can be further reduced.

The slurry thus obtained can be molded by a commonly used molding method, for example, mold casting, continuous casting, press molding and the like. Here, continuous casting is, for example, a method of casting a slurry into a mold having a desired shape moving by a conveyor, and curing while the slurry moves, or directly onto a belt moving by a conveyor. This is a molding method in which a slurry is poured and the slurry is cured while moving. According to this method, a plate-shaped cured product can be manufactured with high efficiency and high productivity.

The cured product obtained by molding is cured as it is or after being subjected to cutting or cutting as required. Curing may be carried out by any method such as room temperature curing, wet curing, steam curing, heated curing, and autoclave curing. In particular, autoclave curing is preferred from the viewpoint of developing strength. Autoclave curing is 120-180 ° C
For 2 to 12 hours.

The cement composition of the present invention is suitable for cement-based building materials, especially for plate-shaped cement-based building materials. Lightweight foamed concrete (AL
C), asbestos cement board, wool cement board, wood chip cement board, pulp cement board, fiber reinforced cement board and the like, and can be used for exterior materials, interior materials, roof materials, ceiling materials and the like.

[0020]

Industrial Applicability The cement composition of the present invention has a good slurry fluidity, excellent workability, and a large initial strength. Further, a hardened cement body obtained by using the same has a small dimensional change and does not cause warping or deformation due to water absorption, and thus is suitable as a plate-like cement-based building material.

[0021]

Next, the present invention will be described in more detail with reference to examples.
As will be apparent, the invention is not limited by these examples.
Not. The components used in the examples are as follows:
It is as follows. (1) Hydraulic composition: Ecocement (Taiheiyo Cement Co., Ltd.)
Municipal waste incineration ash, sewage sludge incineration ash, limestone powder, aluminum
Clinker obtained by firing ash and clay is crushed, and this
It is manufactured by adding gypsum to the baked product.₁₁A ₇Ca
Cl_Two23% by weight of C_Three51% by weight of S, C_TwoS to 15
% By weight, and C_FourClinker group containing 6% by weight of AF
12 parts by weight of anhydrous gypsum per 100 parts by weight of the product
What to do. (2) Blast furnace slag: Esment (Nippon Steel Kanto Esment Company)
Made, Brain specific surface area 4000cm^Two/ G) (3) Silica fume: Egypt (made by EFACO) (4) Slaked lime: Special name of Yoshizawa lime (Ca (OH)_Two95% or more,
(5) water: tap water (6) pulp: virgin pulp (7) glass fiber: alkali-resistant glass fiber 12 mm chop
Dostrand (8) Thickener: HI90SH-4000 (manufactured by Shin-Etsu Chemical Co., Ltd.) (9) Water reducing agent: naphthalenesulfonic acid-based water reducing agent

Examples 1 to 10 and Comparative Examples 1 to 6 Slurries having the compositions shown in Tables 1 and 2 were produced and evaluated for fluidity (flow value), physical properties (specific gravity, flexural strength) by mold forming, and The handleability was evaluated. The results are shown in Tables 1 and 2.

(Preparation method) A predetermined amount of pulp slurry disintegrated with a pulper (capacity: 100 L) is weighed, and a water reducing agent and a thickener are added thereto.
After stirring for 2 seconds, components other than the hydraulic composition and glass fiber are added and stirred for 1 minute and 30 seconds. Next, while rotating the hand mixer at a high speed (1100 rpm), a predetermined amount of the hydraulic composition was added for 10 seconds, and the mixture was further stirred for 30 seconds. Then, glass fiber was added and stirred for 30 seconds.
A slurry was obtained.

(Evaluation method) (1) Fluidity (flow value): Slurry or unevenness that cannot be cast due to visual judgment is marked as “x”, and the slurry can be uniformly cast into the mold without bias. About the thing, the slurry was poured into a ring having an inner diameter of 5 cm and a height of 5 cm, which was set on a mortar table according to JIS R5201, and the surface was smoothed. After that, the ring was gently pulled out, and the table was tapped 10 times. Spread was measured with a caliper. (2) Bending strength test: After curing the molded body in an autoclave,
After drying at 60 ° C. for 2 days, it is cut into a width of 6 cm and a length of 30 cm, and using an autograph, a span of 24 cm and a loading speed of 2 mm.
The bending strength was measured under the condition of / min. (3) Specific gravity: Calculated from the weight and dimensions of the test specimen for bending strength test. (4) Handling: Based on the cured state of the molded body poured into the mold, the mold that could be removed was judged as “○”, and the one that was broken or cracked was judged as “X”.

[0025]

[Table 1]

[0026]

[Table 2]

From the results shown in Tables 1 and 2, each of the cement compositions of the present invention was excellent in fluidity, good in handleability, and had sufficient strength after curing. On the other hand, in Comparative Examples, the strength was not obtained or was low, and in Comparative Examples 1 and 2, handling properties were poor, and molded products were not obtained. In Comparative Example 4, material separation occurred, and Comparative Examples 3, 5
In Nos. 6 and 7, the fluidity was poor and the workability was poor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 22:06 C04B 22:06 Z A 14:42 14:42 Z 16:02) 16:02) A 103 : 60 103: 60 111: 20 111: 20 (72) Inventor Yoshiaki Sakamoto 2-4-2 Daisaku, Sakura City, Chiba Prefecture Inside the Building Materials Techno Laboratory (72) Inventor Shinkichi Tanabe Daisakuji, Sakura City, Chiba Prefecture F-term in Building Materials Techno Research Laboratories, No.4-2, Chome 4G012 PA17 PA29 PB03 PB04 PB11 PB12 PB40 PC12

Claims (5)

[Claims] (A) A hydraulic composition containing a calcined product using at least one selected from municipal waste incineration ash and sewage sludge incineration ash, wherein C ₁₁ A ₇ CaCl ₂ is contained in an amount of 10 to 40% by weight. % And one or more selected from C ₃ S and C ₂ S, and a hydraulic composition containing gypsum, (B) blast furnace slag,
And (C) a cement composition containing slaked lime. 2. The cement composition according to claim 1, further comprising (D) silica fume. 3. The cement composition according to claim 1, further comprising a reinforcing fiber. 4. The cement composition according to claim 1, which is a composition for a plate-like cement-based building material. 5. A method for producing a hardened cement, comprising: shaping and curing a slurry obtained by kneading the cement composition according to claim 1 and water.