JP3947743B2 - Method for producing concrete and apparatus used for the method - Google Patents

Description

  The present invention relates to a method for producing concrete and an apparatus used for the method, and more particularly, to a method for producing high-strength concrete using silica fume slurry and an apparatus used for the method that can exhibit sufficient fluidity and sufficient strength. .

  Conventionally, silica fume, fly ash, fine powder of blast furnace slag, fine powder of limestone, metakaolin, raw consludge, etc. have been used as admixtures added in the production of concrete. When used as an admixture, the micro filler effect and pozzolanic reaction increase the compactness of the cured product and increase the strength, improving fluidity when the amount of binder is large and the water binding ratio is small. Therefore, it can be suitably used as a cement admixture because it has an effective effect of improving workability.

When silica fume is used as an admixture in the production of concrete, it is necessary that the predetermined amount be accurately mixed and uniformly dispersed and kneaded in the concrete within a predetermined time in order to exhibit a predetermined function. There is.
However, when producing high-strength concrete with a large amount of binder and a small water bonding ratio, if silica fume granules or silica fume powder is used as an admixture, the kneading time must be several times longer than the normal kneading time. There is a problem that these silica fume cannot be kneaded so as to be uniformly dispersed in the concrete.

In addition, when conventional silica fume slurry is added to concrete with low unit water volume, such as high-strength concrete, when the moisture content of the aggregate is high, the predetermined unit water volume may be exceeded, or a predetermined amount of silica fume There was a problem such as being unable to add.
However, increasing the concentration of silica fume has increased its usefulness, so there is an urgent need for higher concentration.However, if the concentration of the conventional silica fume slurry is increased simply by reducing water, the viscosity of the silica fume slurry becomes too high. However, there is a problem that the dispersibility in concrete is significantly reduced.

  As shown in FIG. 3, the conventional concrete manufacturing apparatus includes a measuring tank 1h for measuring the amount of silica fume admixture slurry in which silica fume and a high-performance AE water reducing agent are dispersed in advance in the kneaded water, Measuring tanks 1a to 1c for measuring the weight of raw materials such as cement to be kneaded, and mixer 2 for kneading the admixture slurry and raw materials measured by these measuring tanks via supply paths 5a to 5c and 5h. It has a structure provided.

  Using such a conventional apparatus, commercially available silica fume as an admixture, water, and a high-performance AE water reducing agent are respectively added to admixture slurry adjustment storage tanks (not shown) in predetermined amounts, and the inside of the adjustment storage tank The admixture slurry stored in the admixture slurry adjustment storage tank is agitated by a stirrer and maintained in a dispersed state, and is conveyed to the measuring tank 1h using a conveyance means such as a pump at the time of concrete production. The set amount of the admixture slurry is weighed (1h) and charged into the mixer 2 for producing concrete.

In addition, cement, fine aggregate, and coarse aggregate are transferred from respective storage tanks (not shown) to the respective measurement tanks 1a to 1c at the time of concrete production, and the cement, coarse aggregate, After each raw material of the fine aggregate is put into the mixer 2 through the supply paths 5a to 5c, and stirred together with the admixture slurry by the stirrer in the mixer 2, the predetermined kneading is completed. A predetermined amount has been transferred to the agitator wheel 4 via the hopper 3.
Even if concrete is produced using these conventional apparatuses, uniform dispersion of silica fume in the obtained concrete cannot be sufficiently ensured, and plasticization occurs, and therefore, a sufficiently satisfactory strength may not be exhibited. there were.

In view of the above problems, Japanese Patent Application Laid-Open No. 2002-28920 discloses a method for producing concrete by mixing a plurality of materials including an admixture slurry by mixing admixture fine powder and water, and adding γ to the admixture slurry. Irradiate a line to detect the attenuation, and measure the concentration of the admixture slurry calculated corresponding to the attenuation continuously or intermittently. and by a target value of the admixture fine flour powder to be mixed in the concrete method for producing a concrete adjusting by calculating the amount of admixture slurry mixing it is disclosed.

  However, this method is not economical because the apparatus becomes very large, and its control is complicated. In the above-described method for precisely adjusting the concentration of the silica fume slurry as described above, in producing concrete, as schematically shown in FIG. 1b, cement, silica fume slurry, fine aggregate, coarse aggregate, high-performance AE water reduction In this method, the silica fume slurry and the high-performance AE water reducing agent are in direct contact with each other to cause plasticization of the silica fume slurry, and the silica fume into the concrete is mixed. By preventing uniform dispersion, the strength at which the resulting concrete can be expressed is not fully satisfactory.

  In view of these points, Japanese Patent Application Laid-Open No. 2002-137947 discloses the use of a high-performance AE water reducing agent having a specific component composition in order to prevent plasticization of the silica fume slurry and the high-performance AE water reducing agent. Specifically, a silica fume slurry to which silica fume, water, and a polycarboxylic acid ammonium salt are added has been proposed.

However, when a high-performance AE water reducing agent having the above specific component composition is used, the price becomes high, and when used in the region of a low water binder ratio, high dispersibility cannot be obtained, and therefore fluidity retention performance is not obtained. There was a problem that it was not maintained.
JP 2002-28920 A JP 2002-137947 A

The purpose of the present invention is to produce high-strength concrete using a silica fume slurry, and there is no need to use various high-performance AE water reducing agents having specific composition components according to the composition of the concrete. Provided is an extremely simple and high-strength concrete manufacturing method in which a silica fume admixture having a concentration is uniformly dispersed in concrete, and the high-performance AE water reducing agent and the silica fume slurry can ensure fluidity without exhibiting plasticization. .
Another object of the present invention is to provide a useful concrete production apparatus that can easily and economically realize the concrete production method of the present invention.

  In order to solve the above problems, the present inventors have added a high-performance AE water reducing agent to a mixer and kneaded the cement and silica fume in a process of producing concrete using a silica fume slurry. That is, the present inventors have found that the above problem can be solved by making the operation slower than usual, and have reached the present invention.

The method of manufacturing concrete of the present invention, cement, fine aggregate, coarse aggregate, silica fume slurry by kneading mixing water and high performance AE water reducing agent in manufacturing the concrete, cement, fine aggregate and coarse aggregate Then, the mixed water obtained by previously kneading the silica fume slurry and the kneaded water separately was added to the mixer and kneaded, and the cement and the silica fume were kneaded and dispersed with each other. A high-performance AE water reducing agent is added to the subsequent kneaded product and further kneaded.

That is, in the method for producing concrete of the present invention, cement, and kneaded by introducing a fine aggregate and coarse aggregate in the mixer, then the silica fume slurry and the mixing water was charged into the mixer and kneaded, A high-performance AE water reducing agent is added to the mixer and further kneaded into the kneaded material after the cement and the silica fume slurry are kneaded and dispersed with each other.
Then, in the method of manufacturing concrete of the present invention, the silica fume slurry and the mixing water is introduced into the pre-kneaded by weighing after mixer.

The concrete production apparatus of the present invention can realize the above-described method of the present invention, and is an apparatus for producing concrete from cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent. , the mixer raw materials other than high AE water reducing agent has been kneaded, and has a controlled supply path to supply the high AE water reducing agent.

More specifically, the concrete production apparatus of the present invention is an apparatus for producing concrete from cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent, the cement, fine aggregate, Coarse aggregate, a mixture of silica fume slurry and kneaded water, and a high-performance AE water reducing agent are provided for measuring each of the above-mentioned cement, fine aggregate, coarse aggregate, silica fume slurry and kneaded water And the cement and silica fume slurry were kneaded in the mixer, and then the high-performance AE water reducing agent was kneaded from the high-performance AE water reducing agent metering tank. A supply path controlled to supply into the mixer is provided.

The concrete production method of the present invention can produce high-strength concrete very easily, and the resulting concrete can be uniformly dispersed and maintained at a high concentration of silica fume contained, Since it is possible to prevent the occurrence of plasticization of the silica fume slurry and the high-performance reduced AE water reducing agent without having to change the component composition of the high-performance reduced AE water reducing agent, the high-strength concrete having sufficient fluidity can be obtained. be able to. Furthermore, high-strength concrete can be manufactured accurately and in a short time, and the quality of the concrete product can be improved.

  The concrete production apparatus of the present invention can effectively and economically implement the above-described concrete production method of the present invention, and can prevent the plasticization of silica fume slurry. It can be manufactured in time and productivity can be improved.

The present invention will be described by way of preferred examples, but is not limited thereto.
The concrete production method of the present invention kneads materials other than the high-performance AE water reducing agent when kneading cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent. In addition, the high-performance AE water reducing agent is added to the kneaded material after the cement and the silica fume slurry are kneaded and dispersed to each other, and further kneaded.

  Specifically, when concrete is manufactured by introducing raw materials of cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent into the mixer, first, cement, fine aggregate The coarse aggregate, the silica fume slurry and the kneading water are added, for example, for about 10 to 30 seconds, more preferably about 15 to 30 seconds. After these materials are dispersed to some extent, the cement and the silica fume slurry are preferably mixed to some extent. After uniformly dispersing, high-performance AE water reducing agent is added and mixed until each material is sufficiently dispersed to produce concrete.

More specifically, cement, fine aggregate, and coarse aggregate are first put into a mixer and kneaded, then silica fume slurry and kneaded water are put into the mixer and kneaded, and these materials are dispersed to some extent. Thereafter, preferably, after the cement and the silica fume slurry are uniformly dispersed to some extent, a high-performance AE water reducing agent is charged into the mixer and mixed until each material is sufficiently dispersed to produce concrete.
In the method, in which the silica fume slurry and the mixing water is introduced into the pre-kneaded by weighing after mixer.

  By using such a method, regardless of the components of the high performance AE water reducing agent, the plasticization of the silica fume slurry and the high performance AE water reducing agent is prevented, and a concrete having sufficient fluidity and high strength can be obtained. .

The suitable example of the manufacturing method of the concrete of this invention is demonstrated below using FIG. 1a, FIG. 2a, and FIG. 2b.
In order to produce concrete using silica fume slurry as an admixture, a uniform silica fume slurry of a predetermined concentration is introduced into the measuring tank 1d or 1g, and within a predetermined measurement error (silica with respect to the target one-time measurement amount). First, weigh so that the solid content of the fume is within 3%.
In addition, the predetermined concentration of the silica fume slurry before being put into the measuring tank 1d or 1g satisfies the allowable concentration value (display value 0.96 to 1.04) in JIS A 6207 “silica fume for concrete”. It is stirred and controlled to be uniform and constant.

As shown in FIG. 2a, in the case of a method in which silica fume slurry and kneaded water are kneaded in advance, kneading water is further added to the measuring tank 1d, and within a predetermined measuring error (targeted once metering). The metering is continued so that the mass is within 1% of the mass of water.
The amount of kneading water supplied to the measuring tank 1d is calculated by calculating the remaining amount obtained by subtracting the amount of water contained in the silica fume slurry and the amount of surface water in the aggregate from the unit water amount required for the production of one batch of concrete. It is accurately measured and added as the amount of water supplied to the tank 1d.

For reference, as shown in FIG. 2 b, in the case of a method in which silica fume slurry and kneaded water are separately metered (1 f and 1 g) and charged into the mixer 2, the amount of kneaded water supplied to the mixer 2 Is calculated by subtracting the amount of water contained in the silica fume slurry and the amount of surface water in the aggregate from the unit amount of water required for the production of a batch of concrete, and is accurately measured as the amount of water supplied to the mixer 2 Added.

  Conventionally, a high-performance AE water reducing agent is also added to the silica fume slurry metering tank 1h and stirred at the same time (FIGS. 1b and 3), but in the present invention, as described above, the high-performance AE water reducing agent is The silica fume slurry measuring tank 1d or 1g is not charged.

Similarly to the measurement of the silica fume slurry, cement, fine aggregate, and coarse aggregate, which are concrete raw materials, are introduced into the respective measuring tanks 1a to 1c, and the set amount to be supplied to the mixer 2 is measured. .
Similarly, the high-performance AE water reducing agent is not previously mixed with the silica fume slurry as in the prior art, but is separately introduced into the measuring tank 1e, and the amount of mixing is measured.

  The cement, fine aggregate, coarse aggregate, and the mixed liquid in which the silica fume slurry and the kneaded water are mixed are introduced into the mixer 2 through the supply paths 5a to 5d and kneaded (see FIG. 2a), or the weighed cement, fine aggregate, coarse aggregate, kneaded water, and silica fume slurry are introduced into the mixer 2 through the supply paths 5a to 5c and 5f to 5g and kneaded (FIG. 2b). After the raw materials, particularly cement and silica fume slurry are kneaded to some extent in the mixer 2, and preferably in a stable kneaded state, the metered predetermined amount of the high-performance AE water reducing agent is supplied from the metering tank 1e. It is introduced into the mixer 2 via 5e.

Next, all the raw materials charged in the mixer 2 are kneaded until a more stable kneading state is obtained, and the kneading is completed to obtain a concrete material.
Thereafter, the concrete that has been kneaded is transferred to the wet hopper 3, and after the volume is confirmed, the concrete is transferred to the agitator wheel 4 and conveyed.

The concrete production apparatus of the present invention is a ready mixed concrete production apparatus in which the apparatus is incorporated so that the concrete production method of the present invention can be implemented.
Specifically, it is an apparatus for producing concrete from cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent, to a mixer in which raw materials other than high-performance AE water reducing agent are kneaded. And having a supply passage controlled to supply a high-performance AE water reducing agent.

  Preferably, a cement tank, a fine aggregate, a coarse aggregate, a mixed solution in which silica fume slurry and kneaded water are mixed, and a high-performance AE water reducing agent are respectively provided with measuring tanks, and the cement, the fine aggregate, the coarse aggregate, A mixer for kneading the aggregate and the silica fume slurry; after the cement and the silica fume slurry are kneaded in the mixer, the high performance AE water reducing agent is fed from the high performance AE water reducing agent metering tank to the cement and the silica fume slurry. A supply path controlled to supply into the kneaded mixer is provided.

Further , a concrete production apparatus as a reference example includes a measuring tank for measuring cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent, respectively, and the cement, fine aggregate, coarse bone A mixer for kneading the material, silica fume slurry and kneaded water, and after the cement and the silica fume slurry are kneaded in the mixer, the high performance AE water reducing agent is fed from the high performance AE water reducing agent metering tank to the cement and silica fume slurry. Is provided with a supply path controlled so as to be fed into the kneaded mixer.

A preferred example of the outline of the concrete production apparatus of the present invention is schematically shown in FIG. 2a and a reference example in FIG. 2b.
Although not shown in FIGS. 2 a and 2 b, the concrete apparatus includes a silica fume admixture slurry production stirring tank in which a silica fume admixture and water are stirred and mixed and dispersed to prepare a silica fume slurry, and the mixing is performed according to the amount of concrete produced. The admixture slurry adjustment storage tank which stores the admixture slurry transferred from the material slurry production stirring tank and maintains a dispersed state uniformly with a stirrer is provided.

In FIG. 2a, the silica fume admixture slurry is taken out from the admixture slurry adjustment storage tank, and the metering tank 1d for measuring the mixed liquid obtained by mixing the silica fume slurry and the kneaded water introduced into the mixer 2, and further to the mixer 2 are shown. An apparatus including a measuring tank 1a to 1c for measuring the cement, fine aggregate, and coarse aggregate to be input and a measuring tank 1e for measuring a high-performance AE water reducing agent to be input to the mixer 2 is schematically illustrated. Is shown in
The metering tank 1d for measuring the mixed liquid obtained by mixing the silica fume slurry and the kneaded water is charged with the kneaded water. The kneaded water calculates the unit water amount necessary for producing one batch of concrete. Then, an accurate water supply amount obtained by subtracting the water content in the silica fume slurry and the surface water amount in the aggregate from the unit water amount is input.

FIG. 2b shows a measuring tank 1g for measuring the amount of silica fume admixture slurry taken out from the admixture slurry adjusting storage tank and fed to the mixer 2, a measuring tank 1f for measuring the amount of kneaded water, and the mixer. A measuring tank 1a to 1c that measures cement, fine aggregate, and coarse aggregate charged to 2, and a weighing tank 1e that measures high-performance AE water reducing agent charged to the mixer 2. It is shown schematically.
The amount of kneading water charged into the measuring tank 1f for measuring the kneading water is calculated by calculating the unit water amount necessary for producing one batch of concrete, and from the unit water amount, the water content in the silica fume slurry and the surface in the aggregate. The exact amount of water supplied is subtracted from the amount of water.

Further, silica fume slurry, kneaded water, cement, fine aggregate, coarse aggregate, and high-performance AE reduced water measured in each of the above-described measuring tanks 1a to 1e or measured in the measuring tanks 1a to 1c and 1e to 1g. A mixer 2 for producing concrete by kneading the agent is provided. The silica fume slurry, the kneading water, the cement, the fine aggregate and the coarse aggregate are first introduced into the mixer 2 and supplied to be mixed. The passages 5a to 5d or the supply passages 5a to 5c and 5f to 5g are provided in a controlled manner, and these raw materials, particularly the cement and the silica fume slurry are kneaded to a certain degree, and then the cement and the silica fume slurry. Are uniformly kneaded, the supply path 5e is controlled so that the high-performance AE water reducing agent is supplied from the high-performance AE water reducing agent measuring tank 1e to the mixer 2. It has been kicked.
After the high-performance AE water reducing agent is supplied to the mixer 2 in this manner, all materials are uniformly kneaded with a stirrer in the mixer 2 to produce concrete.

Using the concrete manufacturing apparatus of the present invention shown in FIG. 2a, the raw materials whose mixing amounts shown in Table 1 were weighed in the measuring tanks were kneaded by the concrete manufacturing method of the present invention to manufacture concrete.
Specifically, cement, fine aggregate mountain sand, crushed sand, and coarse aggregate are weighed in each of the measuring tanks 1a to 1c so as to have the blending amounts shown in Table 1, and each of the weighed materials is mixed with the mixer. 2 and then kneaded for 15 seconds. Next, the mixed liquid obtained by stirring the silica fume and the kneaded water in the blending amounts shown in Table 1 was introduced into the mixer 2 from the measuring tank 1d, The mixture was further kneaded for 20 seconds. Here, it was confirmed that the cement and the silica fume slurry were kneaded and dispersed.

但し、表中、Ｗは水の質量、Ｂはセメント（Ｃ）とシリカフューム（ＳＦ）との合計質量、ｓは細骨材の体積（山砂（Ｓ_１）と砕砂（Ｓ_２）との合計体積）、aは全骨材の体積（山砂（Ｓ₁）、砕砂（Ｓ_２）及び粗骨材（Ｇ）の合計体積）を表す。

In the table, W is the mass of water, B is the total mass of cement (C) and silica fume (SF), and s is the volume of fine aggregate (mountain sand (S ₁ ) and crushed sand (S ₂ ). Volume), a represents the volume of the total aggregate (total volume of mountain sand (S ₁ ), crushed sand (S ₂ ) and coarse aggregate (G)).

Next, the high-performance AE water reducing agent in which the blending amount shown in Table 1 is weighed is put into the mixer 2 from the high-performance AE water reducing agent measuring tank 1e, and is further kneaded for 280 seconds. Manufactured.
FIG. 4A shows a photograph of a cross section of the obtained concrete (taken with a digital camera by splitting a specimen of φ10 × 20 cm). From the photograph, it can be seen that the obtained concrete has each material uniformly dispersed, especially silica fume uniformly.
In addition, the photograph (size of a glass plate; 30 * 30 cm, image | photographed with the digital camera) of the state of the said silica fume slurry is shown to FIG. 5a. From the photograph, it can be seen that the silica fume slurry is fluid.

(Comparative Example 1)
For comparison, the above cement, fine aggregate mountain sand, crushed sand, coarse aggregate, high-performance AE water reducing agent, silica fume and silica fume slurry obtained by stirring the kneaded water are simultaneously charged into the mixer. Concrete was produced using conventional methods and equipment for kneading (FIGS. 1b and 3).
FIG. 4 b shows a photograph of a cross section of the obtained concrete (split a specimen of φ10 × 20 cm and photographed with a digital camera). However, in the drawings, the circles represent the remaining portions of the plasticized silica fume slurry. Thereby, it turns out that the concrete manufactured by the said method does not disperse | distribute raw materials, especially a silica fume uniformly.
In addition, a photograph of the state of the silica fume slurry (size of glass plate: 30 × 30 cm, taken with a digital camera) is shown in FIG. 5b. It is clear that the silica fume has no fluidity and is plasticized. This is considered to be due to the direct contact between the high-performance AE water reducing agent and the silica fume slurry.

Evaluation Test The compressive strength of the concrete obtained in Example 1 and Comparative Example 1 was measured, and the results are shown in Table 2.
However, the compressive strength was measured by JISA1108 “Concrete compressive strength test method”.

  From Table 2 above, it can be seen that the concrete produced by the method of the present invention has excellent strength development because silica fume is uniformly dispersed.

  Since the concrete obtained using the concrete production method and production apparatus of the present invention can improve the strength development by a very simple method, conventional high-strength concrete such as high-rise buildings, bridge concrete girders, etc. It can be effectively applied to the fields that have been applied.

It is the figure which represented typically an example of the manufacturing method of this invention and the conventional concrete. FIG. 2a is a diagram schematically illustrating an example of a concrete manufacturing apparatus according to the present invention, and FIG. 2b is a diagram schematically illustrating an example of a concrete manufacturing apparatus as a reference example . It is the figure which represented typically an example of the conventional concrete manufacturing apparatus. It is a cross-sectional photograph figure of the obtained concrete. It is a photograph figure of the silica fume slurry used for concrete manufacture.

Claims (2)

In producing concrete by mixing cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent, cement, fine aggregate and coarse aggregate are put into a mixer and then mixed. Separately, mixed water obtained by previously kneading silica fume slurry and kneaded water is put into the mixer and kneaded, and the kneaded product after the cement and silica fume are kneaded and dispersed is added to the high-performance AE. A method for producing concrete, comprising adding a water reducing agent and further kneading. An apparatus for producing concrete from cement, fine aggregate, coarse aggregate, silica fume slurry, kneaded water and high-performance AE water reducing agent, wherein cement, fine aggregate, coarse aggregate, silica fume slurry and kneaded water are mixed. A measuring tank for measuring each of the mixed liquid and the high-performance AE water reducing agent, and a mixer for kneading the cement, fine aggregate, coarse aggregate, and a mixed liquid of silica fume slurry and kneaded water; After the cement and the silica fume slurry are kneaded in the above, the supply path controlled to supply the high-performance AE water reducing agent from the high-performance AE water reducing agent metering tank into the mixer in which the cement and silica fume slurry are kneaded. A concrete manufacturing apparatus comprising:

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