JPH11268937A - Active powder, cement composition and hardened cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active powder in which the solubility of calcium ions and aluminum ions in water is optimally controlled, a high curing rate, and a cured cement body excellent in durability and dimensional stability. Provided are a cement composition and a hardened cement body. SOLUTION: The powder comprises a powder (A) composed of an aluminum compound, a powder (B) composed of a calcium compound soluble in water, and a powder (C) composed of a chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an active powder controlled so that the solubility of calcium ions and aluminum ions in water is optimized, a high curing speed, and a high durability of the obtained cured cement. The present invention relates to a cement composition having excellent dimensional stability and a formed cement hardened body.

[0002]

2. Description of the Related Art In the case of performing work using cement, in order to shorten the construction period, a cement which has a high setting speed and a high setting speed and is excellent in quick setting property is required. In particular, it is important to shorten the construction period in emergency construction such as road construction, repair of railway and aeronautical equipment in urban areas. Also, in a factory that manufactures industrial products made of cement, cement with a high curing speed is desired in order to shorten the period until shipment and simplify the curing equipment.

[0003] As a fast-setting cement having a high setting speed, for example, an ultra-fast-setting cement which exhibits excellent quick-setting properties by forming ettringite at an early stage is disclosed (Japanese Patent Application Laid-Open No. 47-34519). Such an ultra-fast setting cement is commercially available from Chichibu Onoda Corporation under the trade name of jet cement, for example.

[0004] However, ettringite has a swelling property at the time of formation, water of crystallization in ettringite is easily desorbed at a low temperature compared to water of crystallization in ordinary cement hydrate, and unhydrated calcium aluminate is used. Ettringite has a characteristic in that it changes into a monosulfate hydrate having low strength, and has a problem in durability and dimensional stability.

As a method of increasing the curing rate without forming ettringite, for example, calcium aluminate obtained by mixing a clay mineral containing aluminum with slaked lime and applying mechanical energy to the mixture is used. Is disclosed in Japanese Patent Application Laid-Open No. 8-91831. However, although the setting speed of the cement is remarkably high, there is a problem that the setting speed is considerably lower than that of an ettringite-based material (jet cement).

Meanwhile, 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 controlling the amount of calcium ions or aluminum ions in the liquid phase to an optimum amount. 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. Further, 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 producing ettringite hydrate in the curing process.

As calcium aluminate hydrates other than ettringite hydrate, formation of monocarbonate hydrate or Friedel's salt hydrate has been reported in the literature. There is no description on durability [Reference: Inorganic Marterials, Vol. 2, No.
258, 375-382 (1995)].

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an active powder having optimally controlled solubility of calcium ions and aluminum ions in water has been developed. It is an object of the present invention to provide a cement composition in which the speed is high and the obtained hardened cement body has excellent durability and dimensional stability, and a hardened cement body.

[0009]

The active powder according to the first aspect of the present invention (hereinafter referred to as the first invention) has a calorific value of 2 cal / g powder or more when immersed in water. Or 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 (B) composed of a calcium compound soluble in water. And a powder (C) made of chloride.

[0010] The invention described in claim 3 of the present application (hereinafter referred to as "third")
The invention relates to a cement composition comprising:
Or the active powder described in 2 above is added.

The invention described in claim 4 of the present application (hereinafter referred to as the fourth
The hardened cement of the invention) is a hardened cement hydrate obtained by hardening a paste comprising the cement composition of the third invention and water, in which a Friedel salt hydrate is formed. It is characterized by the following.

Hereinafter, the present invention will be described in detail. The active powder of the present invention comprises a mixture of powder (A), powder (B) and powder (C).

As the powder (A), an aluminum compound having a calorific value of 2 cal / g powder or more when immersed in water at room temperature, or immersed in an alkaline aqueous solution having a pH of 12.5 at room temperature. When the amount of aluminum dissolved is 15
Any of aluminum compounds having 0 ppm / g powder or more is used.

When the above powder (A) has a calorific value of less than 2 cal / g powder when immersed in water at room temperature, if it is added to cement, the quick-curing property (particularly the curing speed) is insufficient. Therefore, the calorific value is limited to 2 cal / g powder or more,
It is preferably at least 5 cal / g powder. The upper limit of the calorific value is not particularly limited because the curing rate increases as the calorific value increases, but it is preferably 100 cal / g powder or less.

The calorific value of the powder (A) is as follows.
After immersing the powder (A ₁ ) in a ratio of 20 g to 0 g and stirring for 6 minutes, the calorific value was measured with a calorimeter, and the calorific value obtained by integrating the calorific value from immediately after immersion to 3 hours was defined as the calorific value. .

The specific method of obtaining the powder (A) having a high calorific value when immersed in water is not particularly limited, but includes, for example, a method of applying mechanical energy to an aluminum compound. Although the aluminum compound has low solubility of aluminum in an untreated state, the surface area is increased by applying mechanical energy, the crystal structure is disturbed, and the solubility of aluminum is rapidly increased. Therefore, a predetermined solubility can be imparted by applying mechanical energy.

If the above-mentioned powder (A) is immersed in an alkaline aqueous solution having a pH of 12.5 at room temperature and the amount of aluminum dissolved is less than 150 ppm / g powder, when it is added to cement, it has a fast curing property (particularly, (Hardening rate) is insufficient, so that the amount of aluminum dissolved is limited to 150 ppm / g powder or more, and preferably 300 ppm / g powder or more. Also, since the curing rate increases as the amount of aluminum dissolved increases, the upper limit of the amount of aluminum dissolved is not particularly limited, but 3000 ppm / g powder is preferable.

The amount of aluminum dissolved in the powder (A) is:
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 the powder (A), and the mixture was stirred for 5 minutes, separated into a residue and a filtrate, and the concentration of aluminum present in the filtrate was determined by ICP. This value was taken as the amount of aluminum dissolved. The alkaline aqueous solution used at this time has a pH of 1
It is not particularly limited as long as it is an aqueous solution of 2.5.
An aqueous solution prepared by dissolving an alkali metal salt such as OH or KOH in water and adjusting the pH to 12.5 is preferably used.

A specific method for obtaining the powder (A) exhibiting a high aluminum dissolution amount when immersed in water is as follows.
Although there is no particular limitation, a method of applying mechanical energy described below is used. By applying such mechanical energy, the amount of aluminum dissolved in the powder (A) can be increased to 150 ppm / g powder or more.

Examples of the aluminum compound used as the powder (A) include aluminum hydroxide; aluminum oxide; clay minerals containing aluminum and the like;
For example, kaolinite, montmorillonite, halosite, gypsite, pyrophyllite and the like can be mentioned. Among these, aluminum hydroxide and kaolinite, whose solubility is improved by applying small mechanical energy, are preferred.

The method of applying the mechanical energy includes, for example, a compressive force, a shearing force, an impact force, a frictional force and the like. The method for applying the mechanical energy is not particularly limited. For example, a pulverizing apparatus generally used for the purpose of pulverization can be used. Examples of such a pulverizing device include a ball media type mill in which impact, friction, compression, shearing and the like are combined, such as a ball mill, a vibration mill, a planetary mill, and a media stirring type mill; a roller mill; In addition, it is also possible to use a jet pulverizing apparatus mainly for impact and attrition. Among them, a ball-medium type mill capable of mechanically effectively applying mechanical energy and causing disorder in a crystal structure in a short time is preferable.

The amount of mechanical energy is preferably 0.5 to 30 kWh, more preferably 1 to 10 kWh, per kg of aluminum hydroxide. When the mechanical energy amount is less than 0.5 kWh / kg, the solubility of aluminum ions in the obtained powder (A) becomes low, and the curing rate of the cement composition described below becomes insufficient. On the other hand, if it exceeds 30 kWh / kg, an excessive load is applied to the pulverizing device, and the powder (A) is contaminated by severe wear of the balls and containers as a medium. It has disadvantages in cost and productivity.

The mechanical energy is consumed by the movement and rotation of the grinding device and the ball medium itself based on the total power consumed by the grinding device when aluminum hydroxide is put into the grinding device and actually operated. This is the amount of power from which the amount of power has been subtracted, and indicates the amount of power considered to have been supplied only to the aluminum hydroxide. Here, the amount of power consumed by the operation and rotation of the crushing device and the ball medium itself is the amount of power consumption when the crushing device is operated under the same conditions as when the aluminum hydroxide is charged, except that the aluminum hydroxide is not charged. be equivalent to.

When applying mechanical energy, it is preferable to use a grinding aid usually used when grinding cement clinker, silica sand, limestone and the like. The grinding aid is not particularly limited and includes, for example, alcohols such as methyl alcohol; liquids such as ethanolamines such as triethanolamine; solids such as sodium stearate and calcium stearate;
Examples include gaseous substances such as acetone vapor.

Further, as the powder (A), a calcium aluminate compound such as alumina cement, which is an industrial product, or an aluminum compound which is originally highly reactive to water, such as hydraulic alumina, may be used without treatment. Can also. The above alumina cement is C ₁₂ A ₇ , CA or C
A cement manufactured so that a calcium aluminate compound consisting of A ₂ is a main component, and its use is limited to refractories because the volume change accompanying the phase transition of the hydrate is a problem. It is.

The powder (B) used in the present invention is used to control the amount of calcium ions dissolved in the liquid phase by adding it to the cement described below to an optimum amount. If it is, there is no particular limitation. Examples of the powder (B) include calcium hydroxide (slaked lime), calcium oxide (quick lime), calcium chloride, calcium nitrate, calcium oxalate, calcium silicate, cement, and alumina cement. Of these, calcium hydroxide and calcium oxide are preferred because anions do not inhibit the cement hydration reaction.

The average particle size of the powder (B) is not particularly limited, but is preferably 0.1 to 500 μm, more preferably 0 to 500 μm, from the viewpoint of dispersibility when added to cement and dissolution rate in water. 0.1 to 100 μm.

For the powders (A) and (B), it is not preferable to use a soluble sulfate compound such as aluminum sulfate (sulfate sulfate) or calcium sulfate (gypsum). When a soluble sulfate compound is contained, ettringite hydrate is formed by elution of a sulfur component into water, and thus durability and dimensional stability of the obtained cured product are problematic.

The powder (C) used in the present invention comprises chloride, and when added to cement, reacts with aluminum and calcium ions dissolved from the powders (A) and (B) to form a free (to be described later). Due to the formation of Del's salt hydrate, the setting reaction speed of cement is improved, and a hardened cement body having excellent durability can be obtained.

The kind of such a chloride is not particularly limited as long as it dissolves in water and releases chloride ions. Examples thereof include sodium chloride, calcium chloride, potassium chloride, magnesium chloride, barium chloride, and manganese chloride. , Ammonium chloride and the like. Among these,
Calcium chloride, sodium chloride and potassium chloride are preferred.

The average particle size of the powder (C) is not particularly limited, but is preferably from 0.1 to 100 μm from the viewpoint of dispersibility when added to cement and dissolution rate in water.

When the powder (C) is added to cement, the curing reaction rate of the cement composition described below is further promoted, and a hydrate called Friedel's salt is formed in the obtained cement hardened body. Therefore, the thermal stability is excellent.

In the above active powder, the mixing ratio of the powders (A), (B) and (C) is determined by the following formula in order to obtain a good curing speed: [the number of calcium atoms contained in the powder (B)] /
Ratio of the number of aluminum atoms contained in the powder (A)]
It is preferably 0.1 to 10, more preferably
0.5 to 2. Further, in order to obtain a hardened cement body having good durability, the ratio of [the number of chlorine atoms contained in the powder (C) / the number of aluminum atoms contained in the powder (A)] is as follows:
It is preferably 0.1 to 5, more preferably,
0.2 to 2.

The above powder (A), powder (B) and powder (C)
The method of mixing is not particularly limited, but for example, a mixer such as an omni mixer or an Erich mixer can be suitably used.

In this case, it is preferable to apply mechanical energy to the powder (B) as in the case of the powder (A). When mechanical energy is applied, the solubility in water is improved, and the curing reaction rate with cement is further improved. However, when the powder (A) activated by mechanical energy is used, the mechanical energy is not necessarily applied when the powders (A), (B), and (C) are mixed. It is not necessary.

The cement composition of the third invention is obtained by adding the active powder of the first or second invention to cement. The cement is not particularly limited, for example,
Portland cements such as ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderately heated Portland cement, sulfate-resistant Portland cement; mixed cements such as blast furnace cement, silica cement, fly ash cement; white Portland cement, cement-based Solidified materials, special cements such as alumina cement and the like can be mentioned. Among them, ordinary Portland cement and early-strength Portland cement are preferably used because they are inexpensive and have stable quality.

In the above cement composition, the amount of the active powder to be added is not particularly limited, but is preferably 1 to 100 parts by weight, more preferably 3 to 50 parts by weight, based on 100 parts by weight of the cement. It is. When the addition amount of the active powder is less than 1 part by weight, it becomes impossible to impart a sufficient setting speed and hardening speed to the cement composition,
If the amount exceeds 100 parts by weight, the pot life (time during which moldability can be ensured in the paste state) becomes too short, and curing may start before the work is completed sufficiently.

The method of adding the active powder to the cement is not particularly limited, as long as the active powder is uniformly dispersed in the cement. A mixer such as a Rich mixer is preferably used.

The cement composition may contain aggregates such as gravel and silica sand; reinforcing fibers such as glass fiber, carbon fiber, wollastonite and vinylon; and fillers such as fly ash and silica fume. Further, in order to ensure workability, various cement admixtures such as a setting retarder, a water reducing agent, and a fluidizing agent may be blended.

The hardened cement of the fourth invention is a hardened cement obtained by reacting the above cement composition with water. In the early stage of curing, Friedel salt hydrate (3Ca
O.Al ₂ O ₃ .CaCl ₂ .10H ₂ O) is rapidly generated to accelerate the hardening, and the hydrate is composed of ettringite hydrate (3CaO. Al ₂ O ₃ .3CaSO ₄ .32H ₂ O)
The cured product is more durable because it is considered to be thermally stable as compared with.

The hardened cement body is obtained by mixing and kneading a mixture of the cement composition and other components with water, kneading, shaping into a predetermined shape, and curing. The molding method is not particularly limited, for example, cast molding,
Examples of the method include press molding and extrusion molding, and the curing method is not particularly limited, and examples thereof include a method of standing at room temperature, aging in a heated or heated / humidified atmosphere, and the like.

[0042]

In the first invention (active powder), the solubility of calcium ions and aluminum ions in water is optimally controlled by adding it in the presence of cement and water.
In particular, by adding the powder (C) composed of chloride, Friedel's salt hydrate is rapidly generated in the initial stage of the reaction with water, and the curing reaction speed of the cement is improved. .

The third invention (cement composition) is a cement composition obtained by adding the above-mentioned active powder to cement, and a cement hydrate hardened product (fourth cement product) obtained by reacting the cement powder with water.
Invention) has a Friedel salt hydrate formed, which is thermally more stable than ettringite hydrate contained in conventional fast-setting cement, and has extremely high durability and dimensional stability. Are better.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 17, Comparative Examples 3 to 6) (1) Preparation of Powder (A) Aluminum hydroxide (trade name: C-31, manufactured by Sumitomo Chemical Co., Ltd.) was prepared as an aluminum compound. Using a Ultra Fine Mill (manufactured by Mitsubishi Heavy Industries, Ltd., Model: AT-20), various mechanical energies are applied to the numerical values of Examples and Comparative Examples shown in Tables 1 and 2 to obtain powder (A). Was prepared.

When applying mechanical energy, a zirconia ball having a diameter of 10 mm was used as a ball medium. In addition, the input amount of zirconia balls was 520 kg, and the input amount of aluminum hydroxide was 20 kg. For each aluminum compound,
100 g of ethanol was added.

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 values shown in Table 1 were obtained by changing the treatment time under operating conditions of about 0.5 kWh / kg.

The applied mechanical energy (kWh / k
g) = {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)

(2) Preparation of Powder (B) As a calcium compound soluble in water, slaked lime (calcium hydroxide, manufactured by Kawai Lime Industry Co., Ltd.) was prepared and used as powder (B) as it was. However, with respect to the calcium hydroxide of Example 8, as shown in Table 1, the powder (B) was obtained by applying a mechanical energy of 4 kWh / kg individually in the same manner as the powder (A) of (1). And

(3) Preparation of Powder (C) As chlorides, anhydrous calcium chloride (manufactured by Wako Pure Chemical Industries), sodium chloride (manufactured by Wako Pure Chemical Industries), and potassium chloride (manufactured by Wako Pure Chemical Industries) are used. Prepared and used as powder (C) as it was.

(4) Preparation of Active Powder and Cement Composition The powders prepared in the above (1), (2) and (3) are shown in Table 1,
The mixture was weighed so as to have a mixing molar ratio (A: B: C) shown in FIG. 2 and uniformly mixed using an omni mixer to obtain various active powders. Next, 15 parts by weight (except for Examples 4, 5 and Comparative Example 1) of various active powders were added to 100 parts by weight of ordinary Portland cement (manufactured by Chichibu Onoda), and then mixed with an omni mixer. Thus, a cement composition was obtained.

(Comparative Example 1) Jet cement (manufactured by Chichibu Onoda Co., Ltd.) was used as a cement, and a cement composition to which no active powder was added was used. In the production of the cured product, a setting retarder ("Jet Setter" manufactured by Chichibu Onoda Co., Ltd.) was added to kneading water in an amount of 1 part by weight based on 100 parts by weight of cement in order to improve workability.

(Comparative Example 2) As an aluminum compound,
Aluminum hydroxide (C-3 manufactured by Sumitomo Chemical Co., Ltd.)
1)), using slaked lime (calcium hydroxide, manufactured by Kawai Lime Industry Co., Ltd.) as a calcium compound,
After weighing and mixing Al / Ca in a molar ratio of 2/3, 4 kWh / kg of mechanical energy was applied to the mixture to obtain an active powder, and a cement composition was obtained in the same manner as in the above example. I got something. The active powder conditions and the contents of the cement composition are summarized in Tables 1 and 2.

(5) Preparation and evaluation method of hardened cement body The rapid hardening property of the obtained cement composition and the strength and dimensional stability of the hardened cement body were measured by the following evaluation methods, and the characteristic results were obtained. The results are shown in Tables 1 and 2.

<Evaluation method> (a) Rapid curing property / setting speed Water was added to 100 parts by weight of the obtained cement composition.
A part by weight was poured and kneaded to prepare a cement paste. Regarding the obtained cement paste, JIS R
A setting test was performed in accordance with 5201 (Physical Testing Method for Cement 7. Setting Test), and the start and end of setting were measured, 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. However, when the setting speed is extremely high and measurement is impossible, a setting retarder (Jichibu Onoda Co., Ltd., jet setter) is added to 100 parts by weight of the obtained cement composition. Similar measurements were made.

Curing speed: 3 hours (hr) Compressive strength The above cement paste was cast into a cylindrical shape having a diameter of 5 cm and a height of 10 cm, and after 3 hours from the water injection, the obtained cement cured product was cured. Measure the compressive strength,
This was used as an index of the curing speed. In addition, the measurement of the compressive strength
The test was performed according to JIS R 5201 (physical test method for cement 9. Strength test).・ 7 days bending strength 5cm × 15cm × 1cm thickness of the above cement paste
The molded product was cast into a dumbbell shape, and after 7 days of pouring at room temperature, the flexural strength of the cured product was measured and used as an index of the long-term curing speed.

(B) Dimensional stability 100 parts by weight of the obtained cement composition, 50 parts by weight of No. 8 silica sand (manufactured by Rokuro Mining Co., Ltd.) and 40 parts by weight of water are kneaded. 50mm × 150mm × 10mm
Was cast into a dumbbell shape. Thereafter, curing was performed at room temperature for 7 days to obtain a hardened cement. The obtained cement hardened body was subjected to a three-cycle test in a cycle of drying at 60 ° C. for one day and immersing in water for one day, and measuring the longitudinal dimension before and after the test with a micrometer. I asked. Dimensional change rate (%) = [(dimension after test-initial dimension) / initial dimension] x 100 Evaluation of dimensional stability is indicated by a circle when the dimensional change rate is 0.1 or less, and when it exceeds 0.1 X mark.

(C) Sulfate resistance A test sample similar to the above (b) was prepared and immersed in a solution prepared by dissolving 2 parts by weight of magnesium sulfate (manufactured by Wako Pure Chemical Industries) in 100 parts by weight of water for 20 days. The dimension in the longitudinal direction before and after the test was measured with a micrometer, and the dimensional change was determined by the following equation.

(D) Identification of the type of hydrate formed in the hardened cement In Examples 9 to 17 and Comparative Examples 1, 2, 5, and 6, the amount of the hydrate was 100 parts by weight of the obtained cement composition. 35 parts by weight of water was injected and kneaded to prepare a cement paste. After 3 hours from water injection, pulverize in acetone and
Drying was performed at 0 ° C. for one day. The obtained sample was measured by the powder X-ray diffraction method, and the crystal structure of the formed hydrate was identified. The results are shown in Table 2.・ Friedel salt hydrate (3CaO.Al ₂ O ₃ .Ca
Cl ₂ .10H ₂ O) was designated as F.・ Calcium aluminate hydrate (3CaO.Al ₂ O
₃ · 6H an ₃ O), labeled as H.・ Ettringite hydrate (3CaO.Al ₂ O ₃ .Ca
SO ₄ .32H ₂ O) was designated E. -Those in which no hydrate crystals were detected were indicated as ND.

[0060]

[Table 1]

[0061]

[Table 2]

(Examples 18 to 21, Comparative Examples 9 and 10) The mechanical energy of the powder (A ₁ ) was 0.5 to 4 kWh /
kg of aluminum hydroxide (“C-31” manufactured by Sumitomo Chemical Co., Ltd.), slaked lime or quicklime (Kawai Lime Industry Co., Ltd.) as powder (B), and calcium chloride or potassium chloride as powder (C) Were used. The aluminum hydroxide was obtained by applying various mechanical energies to the numerical values of Examples and Comparative Examples shown in Table 3 using an Ultra Fine Mill (manufactured by Mitsubishi Heavy Industries, Ltd., Model “AT-20”). Powder (A ₁ ) was produced.

The above (A), (B) and (C) were weighed so as to have the ratios shown in Table 3 and mixed with an omni mixer to obtain an active powder. Next, 100 parts by weight of Portland cement (manufactured by Chichibu Onoda Co.) was mixed with the active powder 2
After adding 0 parts by weight, the mixture was mixed with an omni mixer to obtain a cement composition.

(Examples 22 and 23) As powder (A),
Activated powder and cement composition in the same manner as in Example 18 except that alumina cement (“DENKA No. 2” manufactured by Denki Kagaku) and hydraulic cement (“BK-112” manufactured by Sumitomo Chemical Co., Ltd.) were used, respectively. I got something.

Powder (A) used in Examples 18 to 23
The following (6) calorific value and (7) the amount of aluminum dissolution were measured for the obtained cement composition, and the obtained cement composition was cured in the same manner as in Example 1 (setting speed, setting speed), sulfate resistance, and Evaluation of the type of hydrate generated in the hardened cement was evaluated, and the characteristic results are shown in Table 4. For reference, Comparative Examples 1 to 4 are also (6)
The calorific value and (7) dissolved amount were measured and are shown in Table 4.

(6) Calorific value of powder (A) 20 g of the powder was immersed in 20 g of distilled water at 25 ° C., and the total calorific value from immediately after immersion to 3 hours was measured by a calorimeter (Model MMC- 5320 ") and determined the calorific value.

(7) Amount of Aluminum Dissolved in Powder (A) 50 g of an aqueous sodium hydroxide solution (specifically, a 0.17 wt% NaOH aqueous solution) prepared by adjusting 1 g of the powder to a pH of 12.5 at room temperature. After stirring for 5 minutes, the filtrate and the residue were roughly separated by a centrifuge ("H108NA" manufactured by Domestic Centrifuge Co., Ltd.), and further separated again by filter paper ("4A110 mm" manufactured by Advantech Toyo). The aluminum concentration in the finally obtained filtrate was quantified by ICP, and the amount was taken as the amount of aluminum dissolved.

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

The active powder, cement composition and hardened cement of the present invention are constituted as described above, so that the hardening speed is high and the hardened body obtained is made of thermally unstable water. Since it does not contain ettringite hydrate, which is a hydrate, and instead forms Friedel's salt hydrate, it is extremely excellent in sulfate resistance, durability and dimensional stability. Therefore, it is possible to shorten the construction period in emergency work such as road construction, railway and repair of aviation-related equipment in urban areas, and to shorten the time required for shipment at cement secondary products factories. The curing equipment can be simplified.

Claims (4)

[Claims] 1. The calorific value when immersed in water is 2 cal /
g powder or more, or the amount of aluminum dissolved when immersed in an alkaline aqueous solution having a pH of 12.5 is 150 pp.
An active powder comprising a powder (A) comprising an aluminum compound having a m / g powder or more, a powder (B) comprising a calcium compound soluble in water, and a powder (C) comprising chloride. 2. The active powder according to claim 1, wherein the aluminum compound is alumina cement or hydraulic alumina. 3. A cement composition comprising the cement and the active powder according to claim 1 added thereto. 4. A cement hydrate cured product obtained by curing a paste comprising the cement composition according to claim 3 and water, wherein a Friedel salt hydrate is formed in the cured product. Characterized hardened cement.