JP4895693B2 - Method for producing concrete and concrete - Google Patents

Description

  The present invention is a method for producing concrete using a silica fume slurry that facilitates the transportation and handling of silica fume, and in particular, a high strength concrete having a low water binder ratio to which a polycarboxylic acid-based high-performance AE water reducing agent is added. It relates to a manufacturing method.

  In recent years, the amount of high-strength concrete and sprayed concrete in which silica fume is used has been increasing due to the increase in the number of structures and tunnel construction. In order to obtain high-strength concrete, it is necessary to reduce the water binder ratio of the concrete. In particular, in concrete with extremely high design standard strength, it is necessary to use fine fine powder such as silica fume of 1/10 or less of the cement particle diameter. It becomes. Use of a polycarboxylic acid-based high-performance AE water reducing agent mainly composed of a polymer having a graft chain in the molecule in order to impart a predetermined fluidity to concrete having a water binder ratio of 35% or less. Is required.

  Silica fume, on the other hand, is a siliceous ultrafine particle material that has been used as a concrete admixture for the purpose of improving the fluidity of concrete with a pozzolanic reaction, microfiller effect, and low water binder ratio. ing. It is also used for the purpose of improving the working environment, such as reducing the amount of rebound and dust when using shotcrete. When silica fume is blended with these concretes, silica fume is often blended directly in powder form. However, in this case, the silica fume is extremely bulky with a bulk density of about 0.2 to 0.3, so that it is difficult to carry out mass transportation at one time, and dust is easily generated at the time of operation, and handling is difficult. . Further, silica fume has a problem that it is difficult to be uniformly mixed into the concrete and locally aggregates.

  In order to solve such problems, a method has been proposed in which silica fume is added to a high-concentration silica fume slurry by adding a dispersant, which is a high-performance water reducing agent for concrete or mortar, and water. For example, Patent Document 1 includes a naphthalene sulfonic acid formalin condensate system, a melamine sulfonic acid formalin condensate system, a lignin sulfonate system, a polycarboxylate system, a co-condensate system of naphthalene sulfonic acid and lignin sulfonic acid, Condensed triazines are mentioned.

  Patent Document 2 proposes to lower the viscosity by adding sulfuric acid or carbon dioxide as a pH adjuster and adjusting the pH of the silica fume slurry to 1.0 to 5.8.

Furthermore, Patent Document 3 discloses a dispersant and a pH adjuster in which a copolymer of an aliphatic (unsaturated) sulfonic acid and an unsaturated carboxylic acid, or a combination of polyacrylate and naphthalenesulfonic acid formalin condensate is used. Is used together to obtain a low-viscosity silica fume slurry having a concentration of 40 to 60% by weight.
JP 60-129132 A Japanese Patent No. 2672004 Japanese Patent No. 3451407

  However, since the polycarboxylate-based dispersant is not excellent in the dispersibility of silica fume, the resulting slurry has poor fluidity and is not suitable for the production of a high concentration silica fume slurry exceeding 50% by weight. Naphthalenesulfonic acid formalin condensate salt is excellent in silica fume dispersibility, but when mixed with polycarboxylic acid-based high-performance AE water reducing agent widely used in the production of high-strength concrete, the flowability of fresh concrete In order to add a predetermined fluidity to high-strength concrete, it is necessary to add an excessive amount of polycarboxylic acid-based high-performance AE water reducing agent, delaying the setting of concrete, stagnant strength, etc. Problems occur.

  Also, when improving the fluidity of silica fume slurry by adjusting the pH, depending on the type of acid or the amount added, it may adversely affect the properties of high-strength concrete, such as abnormal condensation, reduced strength, abnormal expansion, and rusting of reinforcing bars. There's a problem.

  The present invention provides a method for producing concrete using a high-concentration silica fume slurry for cement admixture that does not adversely affect the properties of the concrete when blended with high-strength concrete to which a polycarboxylic acid-based high-performance AE water reducing agent is added. For the purpose.

  As a result of intensive studies, the present inventors have found that a polycarboxylic acid-based high-performance AE water reducing agent can be used without adversely affecting the physical properties of concrete by using a high-concentration silica fume slurry using an appropriate amount of an appropriate dispersant. The present invention was completed by finding that high strength concrete to be added can be produced.

That is, the present invention
(1) a copolymer having a step of adding a polycarboxylic acid-based high-performance AE water reducing agent, and a polymer composed of a monomer containing a carboxyl group in the molecule and a polymer composed of a monomer containing a sulfonic acid group, or Mixing at least one silica fume slurry to which at least one kind is added from the group of water-soluble polymers consisting of the salt, and the monomer containing the sulfonic acid group is acrylamide methylsulfonic acid or 2-acrylamido-2-methylpropane A method for producing concrete, characterized in that it is a sulfonic acid;
(2) The method for producing concrete according to (1), wherein the amount of the water-soluble polymer added is 0.05 to 2.0% by weight based on silica fume;
(3) The method for producing concrete according to (1) or (2), wherein the concentration of silica fume in the silica fume slurry is 50 to 75% by weight;
(4) The method for producing concrete according to (1), (2) or (3), wherein the ratio of the water binder of the concrete is 30% or less;
(5) Concrete produced by the concrete production method according to any one of claims (1) to (4);

  According to the present invention, there is provided a method for producing concrete using a high-concentration silica fume slurry for cement admixture that does not adversely affect the properties of the concrete when blended with high-strength concrete to which a polycarboxylic acid-based high-performance AE water reducing agent is added. It becomes possible to provide.

Hereinafter, an embodiment of the present invention will be described.

  The method for producing concrete according to the present invention includes a step of adding a polycarboxylic acid-based high-performance AE water reducing agent, polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polystyrenesulfonic acid or a salt thereof, and an unsaturated dicarboxylic acid. A copolymer or a salt thereof having a polymer consisting of a polymer consisting of acrylic acid or methacrylic acid, a polymer consisting of a monomer containing a carboxyl group in the molecule, and a polymer consisting of a monomer containing a sulfonic acid group And a step of mixing a silica fume slurry to which at least one kind is added from the group of water-soluble polymers comprising a copolymer having a salt or a salt thereof.

  Moreover, the concrete according to the present invention is manufactured by the above-described manufacturing method.

Hereinafter, the structure of this invention is demonstrated concretely. As a water-soluble polymer which consists of polyacrylic acid or its salt, sodium polyacrylate etc. can be illustrated.

  Examples of the water-soluble polymer composed of polymethacrylic acid or a salt thereof include polysodium methacrylate.

  Examples of the water-soluble polymer comprising polystyrene sulfonic acid or a salt thereof include sodium polystyrene sulfonate and calcium polystyrene sulfonate.

  A water-soluble polymer comprising a copolymer comprising an unsaturated dicarboxylic acid and a polymer comprising acrylic acid or methacrylic acid or a salt thereof includes a polymer comprising maleic acid and a polymer comprising acrylic acid. Examples thereof include a copolymer having a salt or a salt thereof.

  As a water-soluble polymer comprising a copolymer comprising a polymer containing a carboxyl group in the molecule and a polymer comprising a monomer containing a sulfonic acid group or a salt thereof, acrylic acid-acrylamidomethylsulfonic acid Examples thereof include a copolymer or a salt thereof, a methacrylic acid-acrylamidomethylsulfonic acid copolymer or a salt thereof, and the like. Examples of the monomer containing a sulfonic acid group include 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof.

  Here, the silica fume used in the present embodiment is an ultrafine particle material containing siliceous as a main component, and is made of “silica fume for concrete” defined in JIS A 6207 or of a quality equivalent thereto. As such a silica fume, for example, a by-product of ultrafine particles generated when manufacturing silicon, a silicon-containing alloy, ferrosilicon or the like can be mentioned.

  The amount of the dispersant composed of each water-soluble polymer varies depending on the type of the dispersant and the product, but is generally 0.05 to 2.0% by weight, preferably 0.1 to 1.5% by weight, based on silica fume. Is desirable. If the addition amount of the water-soluble polymer is too small, there is a possibility that a silica fume slurry having a sufficiently reduced viscosity cannot be obtained, and if it is too much, the strength expression of the blended concrete may be insufficient.

  Furthermore, it is preferable that the density | concentration in the slurry of the silica fume in this invention is 50 to 75 weight%. If the silica fume concentration is less than 50% by weight, the amount of water increases, the transportation cost of the silica fume slurry increases, and the blending amount of the silica fume slurry in the high-strength concrete may be limited. On the other hand, if the silica fume concentration exceeds 75% by weight, the effect of lowering the viscosity of the dispersant is not effective, the viscosity of the silica fume slurry becomes too high, and handling such as stirring and quantitative supply becomes difficult, and the dispersibility of the silica fume is reduced. May be insufficient.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

Hereinafter, although the Example of this invention is explained in full detail, this invention is not limited to the said Example.

  Each polymer shown below was added at 0.5% by weight to silica fume to prepare a silica fume slurry having a silica fume concentration of 60% by weight, and the fluidity and strength development of high-strength concrete using this silica fume were evaluated.

[Materials used]
Mixing water: Tap water Cement: Low heat Portland cement (Sumitomo Osaka Cement)
Silica fume: 940-U (Elchem Japan Co., Ltd.)
Fine aggregate: Kimitsu mountain sand coarse aggregate from Chiba Prefecture: Hard sandstone crushed polycarboxylic acid-based high-performance AE water reducing agent from Iwase, Ibaraki Prefecture: Seakament 1200N (Nihon Seika)
Polymer 1: Sodium polyacrylate (A-210: Toagosei)
Polymer 2: Sodium polystyrene sulfonate (Polyty PS-1900: Lion)
Polymer 3: A copolymer having a polymer made of maleic acid and a polymer made of acrylic acid (A-6030: Toagosei)
Polymer 4: Polymer containing a copolymer comprising a polymer comprising monomers containing polymer and a sulfonic acid group consisting of a monomer containing a carboxyl group (A-6017: Toagosei)
Polymer 5: Formalin condensate of naphthalene sulfonate (Mighty 150: Kao)
[Test method]
Each said polymer was added 0.5 weight% with respect to the silica fume, and the silica fume slurry whose concentration of a silica fume is 60 weight% was prepared. The flowability and strength development of high-strength concrete prepared from these silica fume slurries according to the blending ratio shown in FIG. 1 were evaluated.
A concrete containing polymer 1 and containing 2.2% by weight of polycarboxylic acid-based high-performance AE water reducing agent with respect to cement was used as reference example 1. A concrete containing polymer 2 and containing 2.2% by weight of polycarboxylic acid-based high-performance AE water reducing agent based on cement was used as reference example 2. A concrete containing polymer 3 and containing 2.2% by weight of polycarboxylic acid-based high-performance AE water reducing agent based on cement was used as reference example 3. Example 4 was a concrete containing polymer 4 and containing 2.2% by weight of polycarboxylic acid-based high-performance AE water reducing agent based on cement. A concrete containing polymer 5 and containing 2.2% by weight of polycarboxylic acid-based high-performance AE water reducing agent with respect to cement was defined as Comparative Example 1-1. A concrete containing polymer 5 and containing 3.5% by weight of polycarboxylic acid-based high-performance AE water reducing agent based on cement was set as Comparative Example 1-2.

And in the method defined in JIS A 1150, the fluidity of high-strength concrete according to Reference Example 1, Reference Example 2, Reference Example 3, Example 4, Comparative Example 1-1, and Comparative Example 1-2, ie, slump flow. Measured based on. Further, the strength development was measured based on the method defined in JIS A 1180.

[Test results]
The test results are shown in Table 2.

Reference Example 1, Reference Example 2, Reference Example 3 and Example 4 showed a higher slump flow than Comparative Example 1-1. In addition, Reference Example 1, Reference Example 2, Reference Example 3 and Example 4 show higher strength development than Comparative Example 1-1. Such strength development is particularly noticeable in the value at 7 days strength.
In Comparative Example 1-2, although the slump flow is improved to some extent compared to Comparative Example 1-1 by adding a large amount of high-performance AE water reducing agent, strength development is compared with Comparative Example 1-1. However, it can be confirmed from the table that it is inferior. About this point, it turns out that it is especially remarkable in the value in 7-day intensity | strength.

  That is, according to the concrete and the method for producing the same according to the present invention, it is possible to obtain a high-strength concrete composition that does not adversely affect the physical properties of the concrete, that is, does not impair the initial strength development while exhibiting a high slump flow. There was found.

Claims (5)

Adding a polycarboxylic acid-based high performance AE water reducing agent;
Silica fume in which at least one kind is added from the group of water-soluble polymers comprising a copolymer comprising a polymer containing a carboxyl group in the molecule and a polymer comprising a monomer containing a sulfonic acid group or a salt thereof. Mixing at least a slurry,
A method for producing concrete, wherein the monomer containing a sulfonic acid group is acrylamidomethylsulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid. The method for producing concrete according to claim 1, wherein the amount of the water-soluble polymer added is 0.05 to 2.0% by weight based on silica fume. The method for producing concrete according to claim 1 or 2, wherein the silica fume concentration in the silica fume slurry is 50 to 75 wt%. The method for producing concrete according to claim 1, 2, or 3, wherein the water-binding material ratio of the concrete is 30% or less. Concrete produced by the method for producing concrete according to any one of claims 1 to 4.