JP2869489B2 - Hardened spheroidized cement, method for producing the same, and composition for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hardened spheroidized cement, a method for producing the same, and a composition for producing the same.

[Problems to be Solved by Conventional Technology and Invention] Conventionally, various concretes have been manufactured using various cements.

For example, the following concrete cements have the following problems.

Super-fluidized concrete: This is manufactured by adding a fluidizing agent during the production of ordinary ready-mixed concrete or on-site construction, and is used for the purpose of improving the workability and quality of concrete.

However, since the viscosity of the cement paste is abnormally reduced, the aggregate and the cement paste are separated, and a uniform cured product cannot be obtained.

Attempts have been made to maintain the viscosity with a thickener, but the stability is poor and quality control such as blending and kneading is difficult.

Concrete using high-performance water reducing agent: This is manufactured by adding a high-performance water reducing agent to ordinary ready-mixed concrete. The purpose is to lower the water binder ratio to obtain high-strength concrete and high-durability concrete. Used for

However, since the amount of water is extremely suppressed, unhydrated cement is unevenly distributed, and it is difficult to obtain a uniform cured product. Another drawback is that the slump loss is large.

Super retarded concrete: This is manufactured by adding a super retarder to ordinary ready-mixed concrete, and uses the super retardation of setting to suppress the occurrence of cold joints, reduce slump loss, and hydrate. It is used for purposes such as suppressing heat and eliminating nighttime work associated with continuous casting. However, the intensity expression period changes due to changes in environmental conditions, and control is difficult.

Ultra-high-strength concrete: It is manufactured with a low water-binder ratio and the addition of superplasticizers and high-performance water reducing agents, and is used in high-rise buildings and nuclear facilities.

Silica fume has been studied as an admixture, but its strength, slump, slump flow and other fluctuations are so large that it has not yet reached practical use as ready-mixed concrete.

Mass concrete: These are large-scale civil engineering structures (skyscrapers, dams,
Used in nuclear facilities).

Although heat is generated due to the hydration reaction of the cement, this temperature cannot be controlled, and problems such as forced reduction and cracking may occur.

Means and Action for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the problems of the cement concrete described above, and as a result, a cured cement material having excellent fluidity, high strength and high durability has been obtained. Succeeded in providing.

That is, the present invention provides a method of kneading spheroidized cement in which the outer peripheral surface of cement clinker fine particles is shaped by polishing and / or melting, and at least 60% by weight of which has a diameter of 3.9 to 9 μm, aggregate and water. Cured hardened material characterized by being cured and cured, and a method for producing a hardened shaped cement characterized by curing and curing the kneaded product thereof, and a hardened spherical cement product comprising the kneaded product It is a composition for production.

The spheroidized cement used in the present invention has a diameter of 3.
Those having a diameter of 9 to 30.0 μm are preferable because they give good fluidity to the cement mortar or ready-mixed concrete, and the spheroidized cement having a diameter in the numerical range accounts for 60% by weight or more of the total cement. Is preferred.

In addition, a capsule-type spheroidized cement in which the surface of the spheroidized cement is coated with an admixture material, for example, fiber cement, silica fume, or a fluidizing agent, has an active reactivity or has a different surface reactivity. Therefore, various effects are exhibited.

Since the admixture material is uniformly attached to the surface of the capsule type cement, the reaction between the cement and the admixture material (eg, pozzolanic reaction) can be performed uniformly, and the concrete quality (strength, slump, etc.) can be stabilized. Can be achieved.

The spheroidized cement used in the present invention can be produced by employing various methods for producing microspheres such as a known high-speed impact in air stream or a mechanochemical surface fusion method.

The spheroidized cement is a powdery admixture material such as cement fine powder as a child particle, silica fume, etc. (for example, blast furnace slag, fly ash, calcium sulfoaluminate, and other powdery water-reducing materials). Spheroidized cement to which an adhesive, a powdery retarder, etc.) are attached.

Such a spheroidized cement can be manufactured by a known high-speed airflow impact method (a method of spheroidizing a fine-particle material by applying a rotational impact to a fine-particle material by a high-speed airflow in an impact chamber formed of a ring-shaped space). preferable.

Among the thus obtained capsule-type spheroidized cements, spheroidized cements having a diameter of 3.9 to 30.0 μm occupying 60% by weight or more are preferable for producing mortar and ready-mixed concrete.

If the diameter exceeds 30.0 μm, the filling property is reduced, and an unreacted portion remains inside the spheroidized cement during the hydration reaction, which is not effective for developing strength.

On the other hand, if it is smaller than 3.9 μm, the amount of fine powder increases and the cohesiveness increases, and the improvement of the fluidity of mortar and ready-mixed concrete cannot be expected much.

The spheroidized cement having the above particle size range is 60% of the entire cement.
If the amount is less than the weight percentage, sufficient fluidity for mortar paste, ready-mixed concrete, and the like is not provided.

Good fluidity means that the water-cement ratio is low,
That is, even if the amount of water is small, the casting is easy and the amount of water is not excessive, so that high strength mortar and concrete can be manufactured.

Therefore, according to the present invention, a high-strength cement hardened material is produced.

By the way, in the production of cement by a conventional method, as a raw material, limestone, clay, silica stone and iron oxide are mixed in an appropriate ratio, finely pulverized, sent to a rotary kiln through a preheater, and calcined at a high temperature of about 1450 ° C. After obtaining the cement clinker, it is quenched by a cooler and then finely pulverized by a finishing mill (tube mill) to form cement fine particles having a particle size of 1 to 90 μm.

In the production of Portland cement, 3 to 5% of gypsum is added in the step of pulverizing the finishing mill.

That is, the finely ground cement clinker has a particle size of 90.
Although the particle size is less than μm, the outer shape of the fine particles is a square although some corners are formed.

In the present invention, this cement clinker powder (fine particles) is passed through, for example, a commercially available high-speed airflow impactor (Nara Hybridization System) for several minutes, so that the outer peripheral surface is further rounded and becomes spherical. Cement (spherical cement fine particles) is prepared and used as a compounded cement. However, as for the particle size range, it is preferable that the diameter of 3.9 to 30.0 μm accounts for 60% by weight or more.

Incidentally, when the cement clinker powder is spheroidized by the high-speed airflow impact device, the fine powder produced by shaving the corners of the cement clinker at first is not completely spherical yet, but the corners are removed. The spherical cement clinker fills the concave portion and is adsorbed by crushing to form spheroidized cement. As a result, the cement obtained by the treatment has no fine cement powder (because the fine cement powder is mainly adsorbed and filled in the concave portions of the spheroidized cement), and thus becomes a spheroidized cement having a certain particle size range.

Generally, fine cement has a large specific surface area, so that the contact reaction with water is abrupt and the setting is quick, but it causes a decrease in fluidity.

As described above, ordinary cement, for example, ordinary Portland cement, has a rectangular external shape, and a mixture of fine powders, so that the specific surface area is considerably large, and the contact area with water is large, Due to the rapid setting reaction, the fluidity is poor and the heat of hydration reaction is rapidly generated.

As a result, when casting mass concrete or the like, there is a problem that a large temperature difference occurs between the outside air temperature and the concrete, and the concrete cracks.

In contrast, if the spheroidized cement of the present invention is used,
Such a problem is solved, and rapid generation of heat of hydration is eliminated, so that the danger of crack generation in placing mass concrete can be prevented.

Also, for example, the water-cement ratio can be lowered, and in the cement mortar of the same water amount, the mortar of the spheroidized cement has a very large flow value as compared with the mortar of the ordinary Portland cement, and has the same flow value. If so, it is possible to reduce water by 10% or more.

[Examples] Next, the hardened spheroidized cement of the present invention and its production,
Further, specific production examples of the spheroidized cement used in the present invention will be specifically described.

 First, the production of spheroidized cement will be described.

Fine cement clinker particles having a particle size of 1 to 90 μm derived from a finishing mill (tube mill) in a cement production process by a conventional method are used as a commercial high-speed air current impactor “Nara Hybridizer” (trade name: Stock (Manufactured by Nara Machinery Co., Ltd.) and run for 3-20 minutes.

The impact device in a high-speed air current has a structure as shown in FIGS. 1 and 2, and a rotary impact is applied to the fine particle material in an impact chamber formed of a ring-shaped space, thereby converting the fine particle material. It is spheroidized.

1 is a sectional view of the same, and FIG. 2 is a sectional side view thereof, wherein 1 is a casing, 2 is a front cover, 3 is a rear cover, 4 is a turntable, 5 is a blade, and 6 is a rotating shaft. , 7 is a ring-shaped collision chamber, 8 is a ring-shaped stator, 9 is a jacket, 10 is a spheroidized cement discharge valve, 11 is a spheroidized cement discharge chute, 12 is a circulation circuit pipe, and 13 is a supply chute of raw material fine particle cement. Reference numeral 14 denotes a hopper for raw material fine particle cement.

First, the raw material cement in the hopper 14 is supplied from the cement chute 13 to the ring-shaped collision chamber 7.

Then, due to the rotation of the turntable 4 and the blades 5 attached thereto, the raw cement fine particles in the ring-shaped collision chamber 7 are scattered while rotating in the chamber 7 at high speed. Many triangular grooves 8 'provided in
It collides with the surface and the blade 5 while rotating.

After the impinging cement microparticles circulate through one end of the circulation circuit tube 12 opening into the collision chamber 7 and circulate,
It is again introduced into the collision chamber 7 from the other end.

In this manner, the rotational collision is continued a number of times according to the rotation of the turntable 4, and is continued until a desired spherical shape is obtained.

Normally, the rotation speed of the rotating disk 4 is 4000-16000 rpm, and the operation time is 3-20 minutes.

After the work is completed, by lowering and opening the discharge valve 10,
The spheroidized cement is taken out of the chute 11.

By introducing a cooling medium or a heating medium into the jacket 9, the surface treatment of the spheroidized cement, for example, the coating treatment of the admixture can be performed uniformly and reliably.

As described above, spherical cement fine particles are obtained by further removing the corners of the outer peripheral surface.

FIG. 5 is a schematic diagram showing the process from pulverization to spheroidization. That is, the square cement clinker charged into the apparatus in FIG. 5 (a) has its corners shaved in (b) and fine powder is generated.

Next, in (c), the cement clinker whose corner has been cut comes into sliding contact with the surface of the ring-shaped stator while rotating in the apparatus, and then is adsorbed on the surface, and particularly, the concave portion is filled and adsorbed with fine powder. Due to the continuation, as shown in (d), the fine powder has a spheroidized cement fine particle body with a sharpened corner.
The spheroidized cement 20 in which a large amount of fine cement clinker powder 23 is adsorbed and filled in the surface of the 20 ′, particularly in the concave portions, is formed.

Such a spheroidizing method can be performed by other known various devices, for example, Angmill (trade name: improved type of mechanical dry pulverizer manufactured by Hosocala Micron Corporation)
Can also be performed by a mechanochemical surface fusion method using

Further, it can also be carried out by a Kryptron system (trade name: improved type of mechanical fine pulverizer manufactured by Kawasaki Heavy Industries, Ltd.) or the like.

The spheroidized cement obtained by the above-mentioned spheroidizing treatment has a particle diameter of 1 to 30 μm and is a spherical surface with a homogenized surface. Therefore, a bearing effect is produced, and remarkable fluidity can be obtained. It has good viability. As a result, the cement paste containing the spheroidized cement becomes rich in fluidity and excellent in castability.

In addition, the use of self-leveling concrete is very effective because excellent fluidity is imparted.

Further, the admixture (material) can be uniformly attached to the surface of the spheroidized cement.

As the method, for example, 5-30% of silica fume is added when spheroidizing by a high-speed airflow impact method.
As a result, a spheroidized cement 20 whose cross section is shown in FIG.
A capsule-type cement in which 21 layers of ultrafine silica fume particles are adhered to the entire spherical surface.

This capsule-type spheroidized cement can uniformly react silica fume (SiO ₂ ) with cement (pozzolanic reaction), and the quality (strength, slump value) of concrete containing high-strength silica fume, which has been a problem in the past. etc)
Can be stabilized.

If such a capsule-type spheroidized cement is used,
Control of the hydration reaction can be performed reliably and easily.

FIG. 4 shows that the base particle is silica fume 21,
This is a cement composite in which child particles are cement clinker ultrafine particles 22.

This is a composite of ultra-fine cement and cement, which can make the reaction between silica fume and cement uniform, so that ultra-high-strength concrete can be produced by using this. The ultrafine cement clinker used here can be obtained by further classifying the remaining fine fraction as a by-product of the spheroidized fine particle cement clinker obtained by the above-described high-speed air current impactor.

Next, FIG. 6 shows the results of a comparative test on the fluidity (flow value) of the mortar containing the spheroidized cement of the present invention and the conventional mortar containing no portland cement.

The spheroidized cement used in this test was manufactured by a high-speed air current impact method, and spheroidized cement with a diameter of 3.9 to 30.0 μm (average particle size 11.34 μm) accounts for 77.1% by weight. Specimens were prepared in accordance with the test method specified in JISR5201, and adjusted by changing the water-cement ratio to produce test specimens, which were subjected to a flow value test.

From the results shown in FIG. 6, when the spheroidized cement of the present invention is used, the fluidity of the mortar is greatly improved as compared with that using Portland cement, that is, a large flow value (fluidity) with the same amount of water. It can be seen that the water content can be reduced by 10% or more at the same flow value.

As a result, it becomes possible to cast mortar, ready-mixed concrete and the like having excellent fluidity even with a small amount of water, and to provide a high-strength cement hardened product.

Next, an example of producing a high-strength cement hardened material using the spheroidized cement of the present invention will be described.

A kneaded product was prepared by mixing 2 parts by weight of sand and 0.55 parts by weight of water with 1 part by weight of spheroidized cement having a diameter of 5 to 7 μm occupying 80%. The flow value of the kneaded material was 260 mm.

When the kneaded product was poured into a mold and cured and cured,
Compressive strength 300 kg / cm ² at 7 days old, Compressive strength 5 at 28 days old
It was 58 kg / cm ² .

The result was a 27% increase compared to the case using ordinary Portland cement.

Also, in order to obtain the same strength as the compressive strength of concrete using ordinary Portland cement, if spheroidized cement is used, about 50% of the amount of ordinary Portland cement used
An amount of ~ 86% was sufficient.

[Effects of the Invention] As described above, according to the present invention, since the spheroidized cement is spherical microparticles and has a homogenized sphere surface, the spheroidized cement exhibits a bearing effect and is mixed with the spheroidized cement. The material can be given remarkable fluidity, so that the kneaded material has good workability.

Accordingly, the composition for producing a hardened cement containing the spheroidized cement is easy to be cast and cast to obtain fluidity, and it is very advantageous to use it for self-leveling concrete.

In addition, since the casting and filling are performed densely, a high-strength hardened cement product can be manufactured.

Furthermore, the spheroidized cement of the present invention can be obtained by uniformly adhering the admixture material to the surface thereof, and the reaction with the admixture material can proceed uniformly and completely. It is possible to provide a hardened cement having excellent characteristics.

Then, rapid generation of heat of hydration at the time of hardening is eliminated, so that the danger of crack generation during casting of mass concrete can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-speed airflow impact device used in the embodiment, and FIG. 2 is a side sectional view thereof. FIG. 3 is a cross-sectional view of spheroidized cement fine particles having silica fume deposited on the surface, FIG. 4 is a cross-sectional view of silica fume having cement ultra-fine particles deposited on the surface, and FIGS. (D) shows a schematic diagram from the grinding of cement clinker to spheroidization. FIG. 6 is a graph showing the results of a flow value test of the mortar containing the spheroidized cement and the mortar containing the Portland cement. 1: Casing, 2: Front cover, 3: Rear cover, 4: Turntable, 5: Blade, 6: Rotary shaft, 7: Ring-shaped collision chamber, 8: Ring-shaped stator, 9: Jacket, 10: Spheroidization Cement discharge valve, 11: spheroidized cement discharge chute, 12: circulation circuit pipe, 13: raw material fine particle cement supply chute, 14: raw material fine particle cement hopper, 20: spheroidized cement fine particle, 20 ′: Spheroidized cement fine particle body, 21: Silica fume 22: Ultra fine cement clinker 23: Fine cement clinker powder

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-208849 (JP, A) JP-A-3-208848 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 7/48

Claims (11)

(57) [Claims] An outer surface of cement clinker microparticles is spheroidized by polishing and / or melting, and at least 60% by weight or more of the spheroidized cement has a diameter of 3.9 to 30.0 μm, an aggregate and water. A hardened spheroidized cement obtained by curing and kneading a kneaded product. 2. The spheroidized cement is characterized in that an admixture material is adhered to the surface of spheroidized cement particles obtained by polishing and / or melting the outer peripheral surface of cement clinker fine particles. The hardened spheroidized cement according to claim 1, wherein 3. The hardened spheroidized cement according to claim 1, wherein the mixing ratio (weight ratio) of the spheroidized cement, the aggregate and the water is 1: 2.5 to 8.0: 0.17 to 0.75. Stuff. 4. The spheroidized cement according to claim 1, wherein the spheroidized cement is obtained by crushing and spheroidizing fine particles of cement clinker by an impact method in a high-speed gas stream. Hardened cement. 5. The method of claim 1, wherein the outer peripheral surface of the fine particles of the cement clinker is spheroidized by polishing and / or melting, and at least 60% by weight of the spheroidized cement has a diameter of 3.9 to 30.0 μm, an aggregate and water. A method for producing a hardened spheroidized cement, comprising curing the kneaded material. 6. The spheroidized cement is characterized in that an admixture material is adhered to the surface of spheroidized cement particles obtained by polishing and / or melting the outer peripheral surface of cement clinker fine particles. The method for producing a hardened spheroidized cement according to claim 5. 7. The hardened spheroidized cement according to claim 5, wherein the mixing ratio (weight ratio) of the spheroidized cement, the aggregate and the water is 1: 2.5 to 8.0: 0.17 to 0.75. Method of manufacturing a product. 8. The spheroidizing cement according to claim 5, wherein the spheroidizing cement is obtained by pulverizing the cement clinker fine particles by a high-speed air impact method. Manufacturing method of hardened cement. 9. The spheroidized cement according to claim 5, wherein the spheroidized cement is obtained by pulverizing cement clinker fine particles by a mechanochemical surface fusion method. Manufacturing method of hardened cement. 10. The spheroidized cement according to claim 5, wherein the spheroidized cement is a capsule type spheroidized cement obtained by adhering a powdery admixture material as a child particle to the surface of a spheroidized cement particle as a base particle. 9. The method for producing a hardened spheroidized cement according to any one of 9 above. 11. A cement clinker microparticle whose outer peripheral surface is spheroidized by polishing and / or melting, and wherein at least 60% by weight or more of the spheroidized cement has a diameter of 3.9 to 30.0 μm, an aggregate, and water. A composition for producing a hardened spheroidized cement, comprising a kneaded product.