JPH03208848A - Production of hardened matter of high-strength cement - Google Patents

Abstract

PURPOSE:To improve strength and flowability by aging and hardening the kneaded mixture composed of specific spheroidized cement, aggregate and water. CONSTITUTION:The fine particles of cement having 1 to 90mum particle size are supplied from a hopper 14 via a chute 13 into an annular collision chamber 7 and blades 5 mounted to a rotating disk 4 are rotated at 4000 to 1600rpm to splash the fine particles of the cement at a high speed in the chamber 7 while rotating the particles, by which the particles are brought into collision against the surfaces of many triangular grooves 8' provided on the surface of an annular stator 8 and the blades 5 under rotation and are simultaneously circulated in a circulation circuit pipe 12. After the fine particles are thereby speroidized, the particles are taken out of a chute 11 and the spheroidized cement, at least 80% of which has 3.9 to 9mum diameter, is obtd. This cement, the aggregate and the water are kneaded to have 1:(2.5 to 8.0):(0.17 to 0.75) by weight and after the mixture is molded, the molding is aged and hardened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a high-strength cured cement product, and in particular, a method for producing a high-strength cured cement product, in particular a method of producing a high-strength cured cement product, which is made by blending spheroidized cement having a spherical outer peripheral surface and having a specific particle size range. This invention relates to a method for producing a high-strength cured cement product.

[Prior Art and Problems to be Solved by the Invention] Various types of concrete have been manufactured using various types of cement.

For example, there are cement concretes as shown below, but they have the following problems.

■ Superfluidized concrete: This is manufactured by adding a fluidizing agent during the production of regular ready-mixed concrete or during on-site construction, and is used to improve the workability and quality of concrete. .

However, since the viscosity of the cement paste is abnormally reduced, the aggregate and the cement paste separate, making it impossible to obtain a homogeneous cured product.

Attempts have been made to maintain viscosity with thickeners, but
It has poor stability, and quality control such as blending and mixing is difficult.

■ Concrete using a high performance water reducer: This is produced by adding a high performance water reducer to ordinary ready-mix concrete, which lowers the water binder ratio and yields high-strength concrete and high-durability concrete. used for a purpose.

However, since the amount of water is extremely suppressed, unhydrated cement is unevenly distributed, making it difficult to obtain a uniformly cured product, and also having a disadvantage that slump loss is large.

■ Ultra-retarded concrete: This is manufactured by adding an ultra-retarder to ordinary ready-mix concrete. It takes advantage of the ultra-retarded setting property to suppress the occurrence of cold joints, reduce slump loss, and reduce water retention. It is used for purposes such as suppressing heat build-up and eliminating night-time work associated with continuous pouring. However, the period of strength development changes depending on changes in environmental conditions, making it difficult to control.

■ Ultra-high-strength concrete: This is manufactured by keeping the ice binder ratio low and adding superplasticizers and high-performance water reducers, and is used in skyscrapers, nuclear power facilities, etc.

Silica fume has been considered as an admixture, but it has not reached the level of practical use as ready-mixed concrete due to large fluctuations in strength, slump, and slump flow.

■ Mass concrete: This is used for large architectural civil engineering structures (high-rise buildings, dams, nuclear facilities, etc.).

Heat is generated as a result of the hydration reaction of cement, but this temperature cannot be controlled, which can lead to problems such as reduced strength and cracking.

Therefore, the present inventors previously proposed in Japanese Patent Application No. 1-243078 a spheroidized cement in which the outer peripheral surface of cement clinker microparticles is spheroidized by polishing and/or melting, and its usefulness is Since it is spherical, it has a bearing effect, and its mixture is highly fluid, so it is especially suitable for use in self-leveling concrete. Also, since it can be poured densely, it is suitable for high-strength hardened cement. It disclosed that it can be manufactured.

However, it has been difficult to consistently obtain a hardened cement product with high strength.

[Means and effects for solving the problem] As a result of further intensive research, the present inventors have developed a method for consistently obtaining a hardened cement product with high strength.

According to the present invention, a mixture of cement, aggregate, and water has excellent fluidity, allowing dense pouring and filling, and using the minimum necessary amount of cement, a high-strength hardened cement product can always be stably produced. Obtainable.

That is, the present invention comprises a spheroidized cement whose outer peripheral surface is spheroidized by polishing and/or melting of cement clinker microparticles, and at least 80% of which have a diameter of 3.9 to 9 μm, aggregate, and water. This is a method for producing a high-strength hardened cement product, which is characterized by curing and hardening a kneaded product.

In the present invention, it is preferable that 80% or more of the diameter of the spheroidized cement is 3.9 to 9 μm, and it is especially preferable that 80% or more of the spheroidized cement has a diameter of 5 to 71 m.

In addition, the mixing ratio (weight ratio) of spheroidized cement, aggregate, and water
is 1:2.5-8. o: o, preferably from 17 to 0°75.

The spheroidized cement may be produced by pulverizing cement clinker microparticles into spheroids by an impact method in a high-speed air stream, or by pulverizing cement clinker microparticles by a mechanochemical surface fusion method. It may also be obtained by spheroidizing it.

Furthermore, the spheroidized cement is coated with a powdered admixture material such as silica hume (for example, blast furnace slag, fly ash,
Calcium sulfoaluminate, other powdered water reducing agents,
It may also be a capsule-shaped spheroidized cement to which a powdered retarder or the like is attached.

By the way, cement is manufactured by a conventional method by mixing limestone, clay, geyserite and iron oxide as raw materials in appropriate proportions, pulverizing the mixture, sending it through a preheater to a rotary kiln, and firing it at a high temperature of about 1450°C. After obtaining cement clinker, it is rapidly cooled in a cooler, and then passed through a finishing mill (
The cement is pulverized using a tube mill (tube mill) to form fine cement particles with a particle size of 1 to 90 pm.

In the production of Portland cement, 3 to 5% of gypsum is added at the stage of pulverization in the finishing mill.

That is, the finely pulverized cement clinker has a particle size of 90
-m or less, the outer shape of the microparticles is square, although the corners are slightly rounded.

In the present invention, this cement clinker powder (fine particles)
For example, by passing through a commercially available high-speed airflow impact device (Nara Hybridization System) for several minutes, spheroidized cement (spherical cement microparticles) with the outer peripheral surface further rounded and spherical is prepared. This is used as a blended cement. However, it is preferable that 80% or more of the particle size range is 3.9 to 9 pm in diameter.

In addition, the cement clinker was
When the powder is spheronized, the small powder that is created by cutting off the corners of the cement clinker is not yet completely spheroidized, but the corners are removed and the cement clinker becomes approximately spherical.
It fills the recesses of the cement and adsorbs it, forming a spheroidized cement. As a result, the cement obtained by this treatment does not contain fine cement powder (because the fine cement powder is adsorbed and filled mainly in the recesses of the spheroidized cement) and becomes spheroidized cement with a fixed particle size range.

In general, fine cement has a large specific surface area, so the contact reaction with water is rapid, and although it sets quickly, it causes a decrease in fluidity.

Ordinary cement, such as ordinary Portland cement, has a rectangular outer shape as mentioned above, and contains fine powder, so its specific surface area is quite large, and the contact area with water is large. Since a condensation reaction occurs rapidly, fluidity is poor and heat of hydration reaction is rapidly generated.

As a result, when placing mass concrete, etc., there is a problem that a large temperature difference occurs between the outside air temperature and the concrete, causing cracks to occur in the concrete.

On the other hand, if the spheroidized cement of the present invention is used, such problems will be solved, and the sudden generation of heat of hydration will be eliminated.
Therefore, it is possible to prevent the risk of cracks occurring during mass concrete placement.

In addition, for example, the water-cement ratio can be lowered, and for cement mortar with the same amount of water, mortar made of spheroidized cement has a much larger flow value than mortar made of ordinary Portland cement, and even those with the same flow value If so, it becomes possible to reduce water by 10% or more.

According to experiments, 3CaO・Si, the main component of cement,
Ox (CsS> particles participate in the hydration reaction only up to a depth of about 3.5 μm from the surface even when the material is 6 months old.

That is, about 70% of the cement particles with a diameter of 351 m remain unreacted as a core, and coarse particles are not effective in developing strength.

Therefore, in the present invention, spheroidized cement is used, and its diameter is preferably 3.9 to 9.0 pm, particularly preferably 5 to 71 pm.
It is specified in m.

By doing this, the hydration of the cement is completed deep, resulting in a product with high strength. In addition,
Because it is possible to maintain high fluidity by keeping the water-cement ratio low,
Furthermore, it becomes possible to produce a cured cement product with high strength.

Furthermore, the spheroidized cement used in the present invention can also be obtained by spheroidizing cement microparticles by a mechanochemical surface fusion method.

Further, the obtained cement can be used as a mother particle, and an admixture or child particles made of an admixture (for example, silica hume) can be attached to the entire surface of the mother particle to make it double layered and encapsulated into a spherical cement.

Since the admixture or admixture is uniformly adhered to the surface of the encapsulated spherical cement, the reaction between the cement and the admixture or admixture (for example, pozzolanic reaction) can be uniformly carried out, and the quality of concrete ( 9M degree, slump, etc.) can be stabilized.

[Example] Next, a specific example of manufacturing the spheroidized cement used in the present invention and a method of manufacturing a high-strength cured cement containing the spheroidized cement will be described in detail.

First, the production of spheroidized cement will be explained.

Cement clinker microparticles with a particle size of 1 to 90 m derived from a finishing mill (tube mill) in the cement manufacturing process using a conventional method are put into a commercially available high-speed airflow impact bag! is “
"Nara Hybridizer" (trade name: Nara Kikai Seisaku Fukan Co., Ltd.) and operated for 3 to 20 minutes.

The main structure of this high-speed airflow impact device is shown in Figs. 1 and 2, and it is capable of crushing micro-particle materials by applying a rotational impact to the micro-particle materials in an impact chamber consisting of a ring-shaped space. It becomes spherical.

Fig. 1 is a sectional view thereof, and Fig. 2 is a side sectional view thereof, in which 1 is a casing, 2 is a front cover, 3 is a rear cover,
4 is a rotary disk, 5 is a blade, 6 is a rotating shaft, 7 is a ring-shaped collision chamber, 8 is a ring-shaped stator, 9 is a jacket, 1
0 is a discharge valve for spheroidized cement, 11 is a spheroidized cement discharge chute, 12 is a circulation circuit pipe, 13 is a supply chute for raw material fine particle cement, and 14 is a hopper for raw material fine particle cement.

First, raw 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 rotary disk 4 and the blades attached thereto, the raw cement microparticles in the ring-shaped collision chamber 7 are scattered while rotating inside the chamber 7 at high speed, during which the surface of the ring-shaped stator 8 The blade 5 collides with the surface of a large number of triangular grooves 8 provided on the blade 5 while rotating.

The collided cement microparticles enter the pipe from one end of the circulation circuit pipe 12 that opens into the collision chamber 7 and circulate there.
It is introduced into the collision chamber 7 again from the other end.

In this way, the rotational collision is repeated many times as the rotary disk 4 rotates until the desired spherical shape is achieved.

Normally, the rotation speed of the rotary disk 4 is 4000 to 1600 Qrpm.
The operating time is 3 to 20 minutes.

After the operation is completed, by lowering and opening the discharge valve 10,
Spheroidized cement is taken out from the chute 11.

In addition, by introducing a cooling medium or a heating medium into the jagget 9, surface treatment of the spheroidized cement,
For example, the admixture can be coated uniformly and reliably.

In the manner described above, cement microparticles having a rounded outer circumferential surface and a spherical shape can be obtained.

A schematic diagram from this pulverization to spheroidization is shown in FIG. 5. In other words, in FIG. Occur.

Next, in (C), the cement clinker whose corners have been shaved slides against the surface of the ring-shaped stator while rotating within the apparatus, and at this time it is adsorbed to the surface, and in particular, the recesses are filled with fine powder and adsorbed. By continuing, as shown in (d),
Spheroidized cement microparticle body 20 with fine powder having shaved corners
A spheroidized cement 20 is formed in which a large amount of fine cement clinker powder 23 is adsorbed and filled on the surface, particularly in the recesses.

Such a spheroidization method can be performed using various other known devices, such as a mechanochemical surface fusion method using an Ong Mill (trade name; an improved version of a mechanical dry grinder manufactured by Honkawa Micron Co., Ltd.). It can also be done by

In addition, Kryptron System (product name: Kawasaki Heavy Industries, Ltd.)
It can also be carried out using a mechanical pulverizer (an improved version of the mechanical pulverizer manufactured by Kogyo Co., Ltd.).

The spheroidized cement obtained by the above spheroidization treatment is
Since the particle size is 1 to 3011 m and the surface is homogenized and spherical, a bearing effect is produced and remarkable fluidity can be obtained, resulting in good workability. As a result, a cement paste containing the spheroidized cement becomes highly fluid and has excellent pourability.

Further, it is very effective to use in self-leveling concrete because it imparts excellent fluidity.

Furthermore, the admixture (material) can be uniformly adhered to the surface of the spheroidized cement.

As a method for this, for example, 5 to 30% of silica fume is added when spheronizing by high-speed air impact method.

Then, as shown in FIG. 3, the spheroidized cement 2
A capsule-type cement is obtained in which 21 layers of silica hume ultrafine particles are adhered to the entire spherical surface of o.

This capsule-type spheroidized cement is made of silica hume (S
The reaction (pozzolanic reaction) between in, ) and cement can be carried out uniformly, improving the quality (strength, slump value, etc.) of high-strength silica-hyme-containing concrete, which has been a problem in the past.
can be stabilized.

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

In the case shown in Fig. 4, the base particle is silica fume 21,
This is a cement composite whose child particles are cement clinker ultrafine particles 22.

This is a cement composite made of ultrafine particles, and because it can uniformly react between silica hume and cement, it can be used to produce ultra-high strength concrete. The ultrafine particle cement clinker used here can be obtained by further classifying the remaining fine particles as a by-product of the spheroidized fine particle cement clinker obtained by the above-mentioned high-speed air impact device.

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

A mixture was prepared by mixing 1 part by weight of spheroidized cement, of which 80% had a diameter of 5 to 7 μm, with 2 parts by weight of sand and 0.55 parts by weight of water. The flow value of the contaminant is 26
It was 0 mm.

When the mixed material was poured into a mold and cured, it had a compressive strength of 300 kg/kg after 7 days of age, as shown in Section 6.
cm2, and the compressive strength was 558 kg/cm'' at an age of 28 days.

This result was a 27% increase in strength compared to the site using ordinary Portland cement.

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

[Effects of the Invention] As explained above, according to the present invention, the hydration reaction of cement is completely carried out, so high-strength cement can be constantly and stably produced by using the minimum necessary amount of cement composition. A cured product can be produced.

Then, rapid heat of hydration is not generated during curing, and therefore, the risk of cracking during mass concrete placement can be prevented.

Furthermore, since the flow value can be increased by lowering the water-cement ratio, for example, good fluidity can be ensured and casting moldability can also be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a high-speed airflow impact device used in the example, and FIG. 2 is a side cross-sectional view thereof. Figure 3 is a cross-sectional view of spheroidized cement microparticles with silica fume adhered to the surface, Figure 4 is a cross-sectional view of silica hume with cement ultrafine particles adhered to the surface, and Figure 5 (a).
) to (d) show schematic diagrams from pulverization to spheroidization of cement clinker. 1: Casing, 2: Front cover 3: TLT section cover: Rotating disk, 5 blades,
6: Rotating shaft, 7: Ring-shaped collision chamber, 8: Ring-shaped stator 9: Jacket, 10: Spheroidized cement and discharge valve, 11: Spheroidized cement discharge chute, 12: Circulation circuit pipe, 13 Two-raw material microparticle cement Supply chute, 14: Raw material fine particle cement hopper 20: Spheroidized cement microparticles, 20゛: Spheroidized cement microparticle body, 21; Silica hume 22: Ultrafine cement clinker 23: Microcement clinker powder

Claims (1)

[Scope of Claims] (1) Spheroidized cement and aggregate in which the outer peripheral surface of cement clinker microparticles is spheroidized by polishing and/or melting, and at least 80% of the outer peripheral surface thereof has a diameter of 3.9 to 9 μm. A method for producing a high-strength hardened cement product, which comprises curing and hardening a mixture of water and water. (2) Mixing ratio (weight ratio) of spheroidized cement, aggregate, and water
The method for producing a high-strength cured cement product according to claim 1, wherein the ratio is 1:2.5 to 8.0:0.17 to 0.75. (3) The method for producing a high-strength cured cement product according to claim 1 or 2, wherein the diameter of the spheroidized cement is 5 to 7 μm. (4) High-strength cement hardening according to any one of claims 1 to 3, characterized in that the spheroidized cement is obtained by crushing and spheroidizing cement clinker fine particles by an impact method in a high-speed air stream. How things are manufactured. (5) The high-strength cement according to any one of claims 1 to 4, wherein the spheroidized cement is obtained by crushing and spheroidizing cement clinker microparticles by a mechanochemical surface fusion method. Method for producing cured product. (6) The spheroidized cement is a capsule-type spheroidized cement made by adhering powdered admixtures as child particles to the surface of spheroidized cement particles as mother particles. A method for producing a high-strength cured cement product according to any one of the above.