JP2000302500A - Active powder, cement composition and hardened cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide active powder having controlled solubility of calcium ion and aluminum ion in water, provide a cement composition having high hardening speed and giving a hardened product having excellent dimensional stability and durability and provide a hardened material produced from the composition. SOLUTION: The active powder is composed of (A) powder of an aluminum compound dissolving >=150 ppm of aluminum per 1 g of the powder when immersed in an alkaline aqueous solution of pH 12.5, (B) powder of a calcium compound soluble in water and (C) precipitated calcium carbonate light or (D) calcium carbonate whisker. The cement composition is produced by adding the active powder to a cement. The hardened material is produced from the cement composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an active powder in which the solubility of calcium ions and aluminum ions in water is optimally controlled, a high curing speed, and an improvement in the durability and dimensional stability of the resulting cured product. The present invention relates to an excellent cement composition and a cured cement body.

[0002]

2. Description of the Related Art When a construction is performed using cement, a cement having a high curing speed is desired in order to shorten the construction period and urgent construction. Further, in a factory that manufactures industrial products using cement, cement having a high curing rate is desired in order to shorten the period until shipment and to simplify curing equipment and curing equipment. Conventionally, as a fast setting cement having a high setting speed, an ultra-fast setting cement is conventionally known.This cement is commercially available from Chichibu Onoda Co., Ltd. under the trade name of jet cement, for example, and the setting speed is increased by forming ettringite at an early stage. (Japanese Patent Laid-Open No. 47
-34519).

However, this ettringite has a swelling property at the time of formation, water of crystallization in ettringite desorbs at a lower temperature than water of crystallization of ordinary cement hydrate, and reacts with unhydrated calcium aluminate. And changes to a monosulfate hydrate having low strength. Therefore, the cured cement containing ettringite has problems in durability and dimensional stability. On the other hand, as a method of increasing the curing rate without forming ettringite, for example, JP-A-8-91831 discloses a method of mixing a clay mineral containing aluminum and slaked lime and applying mechanical energy to the mixture. A method of adding a calcium aluminate to cement is disclosed.

[0004] However, the above cement has a problem that the setting speed is remarkably high, but the setting speed is considerably lower than that of the ettringite type (jet cement).

In a solid-liquid reaction utilizing calcium ions or aluminum ions in a liquid phase, such as a hardening reaction of cement, the reaction is controlled by optimally controlling the amount of calcium ions or aluminum ions in the liquid phase. Can be promoted. Therefore, in order to increase the setting speed of the cement, it is effective to add an active powder in which the solubility of calcium ions and aluminum ions is controlled to the cement. In order not to impair the durability and dimensional stability of the cured product, it is necessary to produce a calcium aluminate hydrate instead of ettringite hydrate during the curing process.

[0006] Examples of calcium aluminate hydrates other than ettringite hydrate include, for example, Inorganan
ic Materials, Vol. 2, No. 25
8, 375-382 (1995), reports on the formation of monocarbonate hydrate, but there is no description regarding the fast-curing property and durability of the cured product.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an active powder in which the solubility of calcalcium ion and aluminum ion in water is controlled, and It is an object of the present invention to provide a cement composition having a high curing rate, a high curing rate, and excellent dimensional stability and durability of the obtained cured product and a high curing rate.

[0008]

Means for Solving the Problems To achieve the above object, the present invention according to claim 1 (hereinafter referred to as the present invention 1) has a pH
The powder (A) composed of an aluminum compound and the powder (B) composed of a water-soluble calcium compound having an aluminum dissolution amount of 150 ppm / g of powder when immersed in an alkaline aqueous solution of 12.5 are lighter. Calcium carbonate (C)
An active powder characterized by comprising:

The present invention according to claim 2 (hereinafter referred to as "invention 2") provides a powder comprising an aluminum compound having an aluminum solubility of 150 ppm / g or more when immersed in an alkaline aqueous solution having a pH of 12.5. The present invention provides an active powder comprising: a powder (A), a powder (B) comprising a water-soluble calcium compound; and a whisker-like calcium carbonate (D).

[0010] The present invention described in claim 3 (hereinafter referred to as the present invention 3) is characterized in that the aluminum compound is converted to aluminum hydroxide.
The active powder according to claim 1 or 2, wherein mechanical energy of 0.5 to 30 kWh / kg is applied. The present invention according to claim 4 (hereinafter referred to as present invention 4) provides the active powder according to claim 1 or 2, wherein the aluminum compound is alumina cement or hydraulic alumina.

According to a fifth aspect of the present invention, there is provided a cement composition comprising the (Portland) cement and the active powder of the first or second aspect added thereto. I will provide a. The present invention according to claim 6 (hereinafter, referred to as
The present invention 6) provides a cured product obtained from claim 5, wherein a monocarbonate hydrate is formed in the cured product.

The first to fourth inventions are characterized in that the powder (A)
The present invention relates to an active powder comprising (B) and (C) or (D), wherein the fifth invention is a cement composition comprising the active powder of the first invention or the second invention and cement, and the sixth invention is And a cured product produced using the cement composition of the fifth invention. Hereinafter, the present invention will be described in more detail.

The powder (A) has a pH of 12.5 at room temperature.
When immersed in an alkaline aqueous solution of
It is necessary that 50 ppm or more of aluminum is dissolved, preferably 300 ppm or more. If the amount of aluminum dissolved is less than this value, the fast-curing property (particularly the curing speed) becomes insufficient when added to cement. The higher the amount of aluminum dissolution, the faster the curing rate. Therefore, there is no upper limit for the amount of aluminum dissolution, but the effective range is 150 ppm to 3000 ppm.

At this time, the amount of aluminum dissolved was as follows: at room temperature, 50 g of an aqueous alkaline solution having a pH of 12.5 was immersed at a ratio of 1 g of aluminum compound powder, and after stirring for 5 minutes, separated into a residue and a filtrate; Is determined by ICP, and this value is defined as the amount of aluminum dissolved. The aqueous alkaline solution used at this time is not particularly limited as long as the aqueous solution shows a pH of 12.5. Specifically, an alkaline metal salt such as NaOH, KOH or the like is dissolved in water and the pH is adjusted to 12.5. An aqueous solution is preferably used.

A specific method for obtaining the powder (A) having high aluminum solubility is not particularly limited, and examples thereof include a method of applying mechanical energy to an aluminum compound. Examples of the aluminum compound include aluminum hydroxide, aluminum oxide, and clay minerals containing aluminum such as kaolinite, montmorillonite, halothite, gypsite, and pyrophyllite.The solubility of aluminum is reduced by supplying small mechanical energy. Enhanced aluminum hydroxide and kaolinite are preferred.

The above aluminum compound usually has low aluminum solubility when untreated, but the surface area is increased by applying mechanical energy, and further the crystal structure is disturbed, so that the aluminum solubility is rapidly increased. Therefore,
By applying mechanical energy to aluminum compounds such as aluminum hydroxide and kaolinite, the above-mentioned predetermined solubility (amount of aluminum dissolved when immersed in an alkaline aqueous solution having a pH of 12.5 is 150 ppm / g powder 1 g or more) is imparted. can do. Examples of the mechanical energy include energy due to compression force, shear force, impact force, friction force, and the like.

The method for applying the above-mentioned mechanical energy is not particularly limited. For example, the method can be carried out by using a pulverizer generally used for the purpose of pulverization. Such crushing devices include, for example, impact, friction, compression,
Ball mills such as ball mills, vibration mills, planetary mills, and media stirring mills that combine shearing and the like; roller mills; mortars, and the like. In addition, it is also possible to use a jet pulverizing apparatus mainly for impact and attrition. Among them, a ball-medium mill is preferable because mechanical energy can be effectively applied to the powder mechanically and the crystal structure can be disordered in a short time. If the amount of applied mechanical energy is too low, the solubility of aluminum is low, and thus the rapid hardening is insufficient. Becomes intense, which is not preferable.
It is preferably about 0.5 to 30 kWh / kg.

As the powder (A), a calcium aluminate compound such as alumina cement, which is an industrial product, or an aluminum compound which is naturally soluble such as hydraulic alumina can be used without any particular treatment. I can do it. Alumina cement is a cement manufactured so that the calcium aluminate compound consisting of C12A7, CA, and CA2 is the main component, and its volume change due to the phase transition of hydrates is a problem. It is limited. The powder (B) is not particularly limited as long as it is a calcium compound soluble in water,
Examples include calcium hydroxide (slaked lime), calcium oxide (quick lime), calcium silicate, cement and the like.

Incidentally, water-soluble sulfate compounds such as aluminum sulfate (sulfate band) and calcium sulfate (gypsum) cannot be used for the powders (A) and (B). When a water-soluble sulfate compound is contained in the composition, sulfur is dissolved in water, and durability and dimensional stability of the cured product become a problem due to ettringite hydrate formation.

The powder (C) in the present invention 1 is limited to light calcium carbonate among calcium carbonates. Calcium carbonate is generally produced according to its manufacturing method.
It is classified into heavy calcium carbonate obtained by pulverizing limestone and light calcium carbonate obtained by calcining limestone and then carbonating it by carbon dioxide gas treatment. Among them, the light calcium carbonate has higher reactivity with the aluminum compound powder (A) and the calcium compound powder (B) to be added at the same time, the generation reaction of monocarbonate hydrate is quicker, and the durability of the cured body is higher. And excellent dimensional stability. On the other hand, when heavy calcium carbonate is used, the reactivity is low and monocarbonate hydrate is generated. However, other calcium hydrates such as 3CaO.Al2O
Since 3.6H2 O) is also produced, the durability and dimensional stability of the cured product are reduced.

Although the specific surface area of the powder is not particularly limited, from the viewpoint of dispersibility and reactivity when added to cement,
~ 40 m2 / g is preferred. The powder (D) in the present invention 2 is limited to whisker-shaped calcium carbonate among calcium carbonate.

As described above, calcium carbonate is classified into light calcium carbonate and heavy calcium carbonate. Both heavy calcium carbonate and light calcium carbonate generally have a calcite-type crystal structure, and the shape of the calcium carbonate is generally crystalline. It is common to exhibit a spherical shape to reflect the system, but when such a calcium carbonate is used as a starting material, the resulting monocarbonate hydrate has a plate shape, so that the dimensional stability of the cured product is obtained. However, in the present invention, the light calcium carbonate having a whisker shape is used in the present invention 2, since the reinforcing effect of the shape is not sufficient.

This whisker-like calcium carbonate is described, for example, in "Gypsum and Lime" No. 216 (1988).
This has characteristics such as acicular particles having a major axis of about 30 to 50 μm and a minor axis of about 1 to 2 μm. Whisker-like calcium carbonate (D) is grown as calcium carbonate having an aragonite-type crystal structure by appropriately controlling the conditions of carbon dioxide gas treatment after calcining limestone when producing ordinary light calcium carbonate. You can get it.

That is, in terms of the crystal structure, the light calcium carbonate (C) in the present invention 1 often exhibits a spherical shape from the calcite type crystal structure, but is not particularly limited thereto. Calcium carbonate has an aragonite-type crystal structure and has a whisker shape. By using calcium carbonate having such a shape as a starting material, a fibrous monocarbonate hydrate is produced. Is stable (monocarbonate type)
In addition, since it can be grown into a fibrous shape having a high reinforcing effect, it is possible to achieve both dimensional stability and bending strength of the cured cement body. Examples of commercially available whisker-like calcium carbonate (D) include TP-123 manufactured by Okutama Industry Co., Ltd.

The mixing ratio of the powders (A), (B), (C) and (D) is not particularly limited. [The number of calcium atoms / the number of aluminum atoms contained in (A)] is preferably from 0.1 to 10, more preferably from 0.5 to 2.0. In order to obtain good durability of the cured product, [the number of chlorine atoms contained in powder (C) or (D) / the number of aluminum atoms contained in (A)] should be 0.1 to 5.0. Preferably, it is more preferably in the range of 0.2 to 2.0. Powder (A), (B),
The method of mixing (C) or (D) is not particularly limited, and for example, mixers such as an omni mixer and an Erich mixer can be suitably used. In this case, since the powder (A) is a powder activated by applying mechanical energy, it is not necessary to actively apply mechanical energy when mixing them.

The present invention 5 relates to a method of the present invention 1 or 2 for cement.
Is a cement composition obtained by adding an active powder. As the above cement, for example, Portland cement such as ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderate heat Portland cement, sulfate-resistant Portland cement, etc .; mixed cement such as blast furnace cement, silica cement, fly ash cement White portland cement, cement-based solidifying material, etc., of which ordinary portland cement and early-strength portland cement, which are inexpensive and stable in quality, can be suitably used.

In the cement composition of the fifth aspect of the present invention, the amount of the active powder of the present invention is not particularly limited, but is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the cement. If the amount is less than 1 part by weight, the effect of the addition is hardly exhibited, and sufficient setting speed and hardening speed cannot be obtained. On the other hand, if it exceeds 100 parts by weight, the pot life will be too short and curing will begin before sufficient work is performed. Preferably, it is 3 to 50 parts by weight. The method for adding the active powder to the cement is not particularly limited as long as the active powder can be uniformly dispersed in the cement.For example, mixers such as an Erich mixer or an omni mixer can be suitably used. I can do it.

[0028] The present invention 6 is a cured cement obtained by reacting the cement composition of the present invention 5 with water, wherein a monocarbonate hydrate is formed in the cured product. At the early stage of curing, monocarbonate hydrate (3CaO.Al
The rapid formation of 2O3.CaCl2.10H2O promotes hardening, and this hydrate is composed of ettringite hydrate (3CaO.A) contained in conventional fast-setting cement.
It is considered to be chemically more stable than (l2O3.3CaSO4.32H2O), so that the cured product has excellent durability.

The cured product of the present invention 6 can be obtained by mixing and kneading a mixture of the cement composition of the present invention 5 and other components with water, kneading the mixture, molding into a predetermined shape, and curing. Examples of the above-mentioned compounds include aggregates (gravel, silica sand), reinforcing fibers (glass fibers, carbon fibers, wollastonite, vinylon), fillers (fly ash, silica fume) and the like. In addition, various cement admixtures such as a setting retarder, a water reducing agent, and a fluidizing agent may be used to ensure workability. The molding method of the cement hardened body is not particularly limited,
Casting, pressing, extrusion and the like can be mentioned. The curing method is
There is no particular limitation, and examples thereof include a method in which the film is held at room temperature, in a heated atmosphere, or in a heated and humidified atmosphere.

(Action) The active powder of the present invention 1 or 2 comprises powders (A), (B) and (C) or (D),
Since the dissolution characteristics of aluminum ions and calcium ions in water are sufficiently controlled, they can be effectively used for a solid-liquid reaction utilizing aluminum and calcium in a liquid phase. In particular, by adding the calcium carbonate powder (C) or (D), monocarbonate hydrate is rapidly generated in the initial stage of curing of the reaction with water, and the curing is accelerated, and the powder ( The curing speed is faster than that of the active powder consisting of only A) and (B).

In the present invention 2, whisker-shaped monocarbonate hydrate can be produced as the starting material of monocarbonate hydrate by using calcium carbonate having a whisker shape. The bending strength of the cured product is the same level as that of the conventional ettringite-based one. In the present invention 3, a powder obtained by adding mechanical energy of 0.5 to 30 kWh / kg, preferably 2 to 10 kWh / kg to aluminum hydroxide is used as the powder (A) made of an aluminum compound. Body (A)
The above-mentioned object of the present invention can be more reliably achieved by setting the amount of aluminum dissolved when dipping in an alkaline aqueous solution to a suitable range.
In the present invention 4, as the powder (A), a certain amount of aluminum is already dissolved when immersed in an alkaline aqueous solution.
Since alumina cement or hydraulic alumina is used, it can be used without particularly applying mechanical energy.

The cement composition according to the fifth aspect of the present invention is a cement composition obtained by adding the above-mentioned active powder to cement and having a high setting speed and a high curing speed. The hardened cement of the present invention, which is a body, comprises a monocarbonate hydrate which is considered to be a chemically stable hydrate in place of ettringite which is a hydrate having low chemical stability in the hardened body. Since it contains, the cured product is excellent in dimensional stability and durability.

[0033]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Examples 1-3 and Comparative Examples 2, 3)

Powder (A) Aluminum hydroxide (C-31, manufactured by Sumitomo Chemical Co., Ltd.) was prepared, and the mechanical energy shown in Table 1 was applied thereto using an ultrafine mill (AT-20, manufactured by Mitsubishi Heavy Industries, Ltd.). Was used as powder (A). When applying mechanical energy, a zirconia ball of 10 mmφ was used as a ball medium. The input amount of zirconia balls was 520 kg, the input amount of aluminum hydroxide was 20 kg, and 100 g of ethanol was added to each aluminum compound as a grinding aid.

The mechanical energy applied to the aluminum hydroxide is an average energy density (an average energy per hour, and is a value obtained by dividing the mechanical energy applied to the compound obtained by the following formula by the processing time. )But,
The mechanical energy shown in Table 1 was obtained by changing the treatment time under operating conditions of about 0.5 kWh / kg. Applied mechanical energy (kWh / kg) = 電力 Amount of power consumed during operation during aluminum compound treatment (kWh)-Amount of power consumed during idle operation before input of aluminum compound (kWh)
)｝ ÷ Amount of treated compound (kg) The amount of aluminum dissolved in powder (A) was determined by the following method and is shown in Table 1.

Powder (B), (C) Slaked lime (manufactured by Kawai Lime Industry Co., Ltd.) was used as powder (B). The powder (C) has the manufacturer shown in Table 1, respectively.
Calcium carbonate having a product name, shape and crystal structure was used.

Preparation of Active Powder and Cement Composition The above-mentioned powders (A), (B) and (C) were converted into (A):
(B): (C) was weighed so that the weight ratio was as shown in Table 1, and uniformly mixed with an omni mixer to obtain various active powders. The active powder was added in an amount of 20 parts by weight with respect to 100 parts by weight of ordinary Portland cement (manufactured by Chichibu Onoda), and then mixed with an omni mixer to prepare a cement composition. Preparation and evaluation method of hardened cement body The rapid hardening property of the obtained cement composition and the hydrate structure and dimensional stability of the hardened cement body were evaluated by the following methods, and the results are shown in Table 1.

[Evaluation Method] (1) Amount of Aluminum Dissolved 1 g of the powder (A) shown in Table 1 was subjected to pH 12.5 at room temperature.
Immersed in 50 g of an aqueous sodium hydroxide solution (specifically, a 0.17% by weight aqueous NaOH solution), stirred for 5 minutes, and then centrifuged (H1 manufactured by Domestic Centrifuge Co., Ltd.).
08NA), the filtrate and the residue were roughly separated, and further separated again using filter paper (4A110 mm manufactured by Advantech Toyo). The aluminum concentration in the finally obtained filtrate was quantified by ICP (Inductively Coupled Plasma Atomic Emission Spectrometry) to determine the amount of aluminum dissolved.

(2) Rapid curing property / setting speed 35 parts by weight of water was injected and kneaded with 100 parts by weight of the obtained cement composition to prepare a cement paste. Regarding the obtained cement paste, JIS R5201
A setting test was performed according to (Physical Testing Method for Cement 7. Setting Test) to determine the start and end of setting, and the difference was used as an index of setting speed. As a setting tester, an automatic setting tester (MIC-308-1, manufactured by Enai Seisakusho) was used.・ Curing speed The above-mentioned cement paste was cast into a cylindrical shape having a diameter of 5 cm and a height of 5 cm, and after 3 hours from the water injection, the compressive strength of the cured body was measured. did.

(3) Dimensional stability (sulfate resistance) 100 parts by weight of the obtained cement composition, 50 parts by weight of No. 8 silica sand (manufactured by Rokuriya Mining Co., Ltd.), and 40 parts by weight of water are kneaded and obtained. The kneaded material was cast into a dumbbell shape of 50 mm × 150 mm × 10 mm. Thereafter, curing was performed at room temperature for 7 days to obtain a hardened cement. The obtained cured product was immersed in a 2% by weight aqueous magnesium sulfate solution for 20 days, and the longitudinal dimension before and after the test was measured with a micrometer, and the dimensional change was determined by the following equation. Dimension measurement is 60 before and after the test
After drying at a temperature of 1 day for 1 day, the temperature was measured. Dimensional change rate (%) = (saturated size after test-initial size) / initial size x 100 The dimensional stability was evaluated as "good" when the dimensional change rate was 0.2 or less, and as "x" when the dimensional change rate exceeded 0.2. did.

(4) Flexural strength of the cured product Room temperature of the cured product prepared under the same conditions as the measurement of the dimensional change described above.
Table 1 shows the results of a three-point bending strength test performed at a span of 120 mm during day curing. (5) Identification of Crystal Structure of Hydrate Generated in Cured Body 35 parts by weight of water was injected and kneaded with 100 parts by weight of the obtained cement composition to prepare a cement paste. After 3 hours from the water injection, the mixture was pulverized in acetone and dried at 60 ° C. for 1 day. The obtained sample was measured by the powder X-ray diffraction method, and the crystal structure of the formed hydrate was identified. Specifically, RINT1000 manufactured by Rigaku Corporation was used for the X-ray diffractometer, and a diffraction peak of 5 ° to 60 ° was obtained by 2θ / θ scan using a Cu tube to obtain JC.
The crystal structure of the hydrate formed by the PDS card was identified.

(Examples 5 and 6) Except that alumina cement (manufactured by Denki Kagaku Kogyo, Denka No. 2) and hydraulic alumina (manufactured by Sumitomo Chemical Co., Ltd., BK-112) were used in an untreated state as powder (A). In the same manner as in Example 1, an active powder and a cement composition were prepared, a hardened cement body was prepared, and the evaluation was performed.

(Comparative Example 1) A cement composition was prepared by using jet cement (manufactured by Chichibu Onoda Co., Ltd.) without adding active powder. However, in order to improve the workability, a jet setter (Jet Setter, manufactured by Chichibu Onoda) was added as a setting retarder only 1 part by weight (the number of parts added to 100 parts by weight of cement) to the kneading water in advance to evaluate the properties. Was. The quick-setting properties of this cement composition and the hydrate structure and dimensional stability of the cured cement were evaluated in the same manner as in the examples. The dissolution amount of aluminum was similarly evaluated using jet cement itself instead of powder (A). The results are shown in Table 1.

(Examples 7 to 11 and Comparative Example 4) Manufacturers, product names,
Except for using calcium carbonate with shape and crystal structure,
In the same manner as in Example 1, an active powder and a cement composition were prepared, and a hardened cement was produced. As an evaluation method,
A hydrate formed in the cured product was identified, and the same evaluation as in Example 1 was conducted except that the shape of the crystal structure was observed, and the results are shown in Table 1. Observation of the crystal structure of the hydrate can be performed with a scanning electron microscope (JSM-5800LV, JEOL Ltd.)
Was used to determine whether it was plate-like or fibrous. The scanning electron microscope (SE) of the whisker-shaped calcium carbonate having the aragonite crystal structure used in Example 9 and the spherical calcium carbonate having the calcite crystal structure used in Comparative Example 4
M) a photograph, a photograph of the crystal structure of the hydrate formed in the cured product obtained using these calcium carbonates, and a chart showing the X-ray diffraction peak of the hydrate formed in the cured product. Was presented.

[0045]

[Table 1]

[0046]

The active powder according to the present invention is constituted as described above, and since the dissolution characteristics of aluminum ions and calcium ions in water are optimally controlled, the active powder hardens when reacted with water. Speed is fast. The cement composition according to the present invention is configured as described above, and when the cement composition is reacted with water, the setting speed and the setting speed are both high, and the cured cement body according to the present invention obtained at that time. Since a chemically stable monocarbonate hydrate is formed, is extremely excellent in durability and dimensional stability. Therefore, it is possible to shorten the construction period in emergency work such as road construction, repair of railways and aviation-related facilities in urban areas. Can be simplified.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of calcium carbonate used in Example 9 of the present invention (at a magnification of 7000 times).

FIG. 2 is an electron micrograph of calcium carbonate used in Comparative Example 4 (magnification: 3,000).

FIG. 3 is an electron micrograph of a hydrate of a hardened cement obtained in Example 9 (magnification: 6500).

FIG. 4 is an electron micrograph of a hydrate of a cured cement body obtained in Comparative Example 4 (magnification: 6500).

FIG. 5 is a chart showing peaks of X-ray diffraction results for judging a crystal structure of a hydrate of a hardened cement obtained in Example 9.

6 is a chart showing peaks of X-ray diffraction results for judging a crystal structure of a hydrate of a hardened cement obtained in Comparative Example 4. FIG.

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Claims (6)

[Claims] 1. An aluminum dissolving amount of 150 ppm / g of powder when immersed in an alkaline aqueous solution having a pH of 12.5,
An active powder comprising the powder (A) composed of the above aluminum compound, the powder (B) composed of a calcium compound soluble in water, and the light calcium carbonate (C). 2. A powder (A) composed of an aluminum compound having an aluminum solubility of 150 ppm / g or more when immersed in an alkaline aqueous solution having a pH of 12.5 and a powder composed of a calcium compound soluble in water ( An active powder comprising B) and whisker-like calcium carbonate (D). 3. The active powder according to claim 1, wherein the aluminum compound is obtained by applying mechanical energy of 0.5 to 30 kWh / kg to aluminum hydroxide. 4. The active powder according to claim 1, wherein the aluminum compound is alumina cement or hydraulic alumina. 5. A cement composition comprising the cement and the active powder according to claim 1 added thereto. 6. The cured product obtained from claim 5, wherein
A hardened cement body, wherein a monocarbonate hydrate is formed in the hardened body.