JP2007197290A - Method for preparing concrete and admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing concrete, by which concrete having desired fluidity can be obtained easily and to provide an admixture to be mixed in cement. <P>SOLUTION: The admixture A to be mixed in cement CM contains a thickener 1 having an amino or amide group and a sulfonate group and a polycarboxylic acid-based water reducing agent 2. The method for preparing concrete comprises a step of mixing the admixture A with a concrete material CZ containing cement CM and water at the least. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing concrete and an admixture mixed with cement.

  Conventionally, depending on the place and purpose of placing concrete, those having different fluidity before hardening, that is, those called high fluidity concrete, medium fluidity concrete, etc. are used properly. Various methods for producing concrete for obtaining the desired fluidity as described above have been proposed (see, for example, Patent Document 1). And in such concrete, a water reducing agent is used in order to provide appropriate fluidity, and a water reducing agent is used in order to reduce material separation accompanying improvement in fluidity.

  In order to obtain the desired slump flow value, that is, fluidity, various thickeners and water reducing agents for mixing with water, cement and the like during concrete production have been proposed (see, for example, Patent Document 2, 3 or 4). .

  In addition, the biggest factor that affects the fluidity of concrete during placement is the amount of water mixed during concrete production. In other words, the use of the water reducing agent described above gives appropriate fluidity to the concrete, while the cement dispersibility is excellent, so even if the amount of water in the concrete varies slightly, the fluidity changes significantly. is there.

In addition to reducing material separation as described above, the above thickener is said to have an effect of stabilizing fluidity change due to fluctuations in water to some extent.
JP-A-9-216218 Japanese Patent Laid-Open No. 9-2856 Japanese Patent Laid-Open No. 2001-19518 JP 2005-505127 A

  However, in actual concrete production sites, there is water other than the mixing water, such as the surface water of the aggregate and the cleaning water remaining in the mixer that mixes the concrete material due to cleaning after the previous mixing. include. Therefore, the amount of kneading water added at the time of manufacture is calculated by subtracting water other than kneading water from the blend.

  On the other hand, at the actual concrete manufacturing site, the amount of surface water of the aggregate as described above and the amount of cleaning water remaining in the mixer can be constantly fluctuated due to, for example, the weather. In such an actual manufacturing site, it is difficult to accurately set the amount of mixing water in consideration of the amount of water other than the mixing water described above for each batch in which cement or the like is mixed in the mixer. is there. Therefore, blending control is often performed with a high safety factor in terms of strength, and according to this control, strength can be ensured even if the amount of water in the produced water varies. However, depending on the target concrete conditions, the change in fluidity due to fluctuations in the amount of water is large, and adjustment of the slump flow value may be very difficult.

  This invention pays attention to such a malfunction, and provides the manufacturing method of concrete which can obtain desired fluidity easily, and the admixture mixed with cement.

  In order to achieve such an object, the present invention takes the following measures. That is, the method for producing concrete according to the present invention includes a concrete material containing at least cement and water, a thickener containing an amino group or an amide group, and a sulfonic acid group, and a polycarboxylic acid-based water reducing agent. It is characterized by mixing.

  The admixture used by mixing with the cement according to the present invention includes a thickener containing an amino group or an amide group and a sulfonic acid group, and a polycarboxylic acid-based water reducing agent. It is.

  Here, the term “concrete” is a concept that includes not only concrete in a narrow sense in which cement, water, and aggregate are mixed, but also, for example, what is configured by mixing cement and water without using aggregate.

  If it is such, even if the amount of water other than kneading water fluctuates to some extent at the time of concrete production, a stable fluidity, that is, a slump flow value can be obtained at the time of placing concrete. Therefore, the trouble of resetting the amount of mixing water each time according to the situation of the concrete manufacturing site can be saved effectively.

  Further, the addition amount of the thickener to the cement is desirably 0.01 to 0.2% by weight, and the ratio of the thickener to the water reducing agent is 1:30 to 1: 200. It is more preferable.

  The thickener specifically includes (meth) acrylamide-acrylic sulfonic acid, and a water-soluble or water-swellable sulfo group-containing associative copolymer based on (meth) acrylamide or N-vinyl compound. desirable.

  The number average molecular weight of the copolymer is preferably 50,000 to 20000000, more preferably the number average molecular weight is 50,000 to 10000000, and further preferably the number average molecular weight is 50,000 to 8000000.

  The water reducing agent is preferably a polycarboxylic acid-based high performance AE water reducing agent.

  The concrete production method according to the present invention is a concrete production method in which a batch mixer is used, and mixing by the mixer is continuously performed in a plurality of batches, and an amino group or an amide group is used as a feed material to the mixer. , And a thickener containing a sulfonic acid group, a polycarboxylic acid-based water reducing agent, cement, mixing water, and aggregate, and the amount of the mixing water in each batch is constant. It is characterized by doing.

  If this is the case, it has a stable fluidity even if there is a fluctuation in the amount of water actually mixed due to the cleaning water remaining in the mixer and the surface water of the aggregate between multiple batches at the concrete manufacturing site. It becomes possible to produce concrete.

  According to the present invention, even when the amount of water other than kneaded water fluctuates to some extent during concrete production, a stable fluidity, that is, a slump flow value can be obtained when placing concrete. Therefore, the trouble of resetting the amount of water each time according to the situation of the concrete manufacturing site can be saved effectively.

  In addition, the desired fluidity can be achieved even if the total amount of water actually mixed changes due to fluctuations in the amount of cleaning water remaining in the mixer and the surface water of the aggregate between multiple batches at the actual concrete manufacturing site. It becomes possible to produce concrete having a stable structure.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a mode in which a concrete material CZ containing at least a cement CM and a predetermined amount of mixing water WH, which will be described later, and an admixture A, which will be described later, are continuously mixed in a mixer M for each batch. .

  Here, in the concrete manufacturing method according to the present embodiment, the amount of the mixing water WH in each batch including the first batch FB to be mixed first in the mixer M and the continuous batch CB to be mixed after the second time is determined. It is characterized by being constant.

  And the admixture A used by mixing with the cement CM according to this embodiment includes a thickener 1 containing an amino group or an amide group and a sulfonic acid group, and a polycarboxylic acid-based water reducing agent 2. It is characterized by. Furthermore, the concrete manufacturing method according to the present embodiment is characterized in that the admixture A is mixed with a concrete material CZ containing at least cement CM and water.

  Hereinafter, the concrete manufacturing method according to this embodiment will be described in detail.

  FIG. 1 shows, for example, when a concrete material CZ and an admixture A are mixed in a mixer M at a general concrete manufacturing site, for example, the first time from the start of the start of work when the mixer M is sufficiently dried. One batch FB and a continuous batch CB containing mixer cleaning water WM described later in the mixer M, which is performed after the inside of the mixer M is cleaned after the first batch FB, are schematically shown. is there.

  In this embodiment, the concrete material CZ contains the mixing water WH, cement CM, aggregate K, and limestone fine powder LP. In the embodiment, the mixing water WH is set so that 185 kg is mixed in producing 1 cubic meter of concrete. Cement CM is set to mix 386 kg per cubic meter. The aggregate K is composed of the fine aggregate K1 and the coarse aggregate K2. In this embodiment, the fine aggregate K1 is set to be mixed with 802 kg per cubic meter and the coarse aggregate K2 is mixed with 888 kg. . The fine limestone powder LP is set so as to mix 107 kg per cubic meter.

  Here, the concrete material CZ usually contains an indefinite amount of the surface water WK of the aggregate K in addition to the above-mentioned mixing water WH. In addition, the continuous batch CB contains an indefinite amount of the mixer cleaning water WM remaining when the mixer M is cleaned. That is, the total amount WT of water actually mixed in the concrete material CZ varies depending on the presence / absence of the mixer cleaning water WM and the fluctuation of the mixer cleaning water WM and the surface water WK of the aggregate K. Therefore, the amount of the mixing water WH described above is set to an amount that is set in anticipation of the amount of the surface water WK of the aggregate K and the amount of the mixer cleaning water WM. Of course, although not shown, the case where the mixer cleaning water WM is included in the first batch of the start is also assumed.

  Therefore, in the concrete production method according to the present embodiment, as described above, in addition to the concrete material CZ, the thickener 1 containing an amino group or an amide group and a sulfonic acid group, a polycarboxylic acid-based water reducing agent 2 and It is characterized by mixing admixture A containing

  The thickener 1 is added in an amount of 0.01 to 0.2% by weight to the cement CM. Specifically, in this embodiment, 118 g is mixed per cubic meter. Further, the thickener 1 includes (meth) acrylamide-acrylsulfonic acid, and a water-soluble or water-swellable sulfo group-containing associative copolymer based on (meth) acrylamide or an N-vinyl compound. A copolymer having a number average molecular weight of 50,000 to 20,000,000 is employed.

  More specifically, the copolymer constituting the thickener 1 is mainly composed of four types of monomers 10a, 10b, 10c, and 10d. As a first example of a combination of four types of monomers 10a, 10b, 10c, and 10d that can constitute the thickener 1 according to this embodiment, the monomer 10a is 2-acrylamido-2-methylpropanesulfonic acid, and the monomer 10b is N, N-dimethylacrylamide, monomer 10c as [2- (methacrylamide) -propyl] -trimethylammonium chloride, monomer 10d as tristyryl polyethylene glycol-1100-methacrylate (Rhodia Corporation's Sipomer SEM 25; 25 ethylene glycol units) Have). As a second example, monomer 10a is 2-acrylamido-2-methylpropanesulfonic acid, monomer 10b is N, N-dimethylacrylamide, monomer 10c is [3- (methacryloylamino) -propyl] -trimethylammonium chloride, Examples of the monomer 10d include tristyryl polyethylene glycol-1100-methacrylate (SEM 25). In addition, examples shown in Examples 3 to 9 described in Table 1 can be given.

  The water reducing agent 2 employs a polycarboxylic acid-based high performance AE water reducing agent 2. And the ratio of the thickener 1 and the water reducing agent 2 is 7.395 kg per cubic meter so that it may become 1: 30-1: 200.

  As described above, in the present embodiment, by using the above-mentioned admixture A, the increase or decrease of about 5% in the total amount WT of water mixed as a whole due to the increase or decrease of the mixer cleaning water WM and the surface water WK of the aggregate K. Even if this occurs, the slump flow value, that is, the change in fluidity can be stabilized to a practically satisfactory level. That is, by applying such an admixture A, even if the amount of water mixed in addition to the mixing water WH blended as the concrete material CZ at the time of concrete production fluctuates to some extent, A slump flow value can be obtained. Therefore, the trouble of resetting the amount of mixing water WH each time according to the situation of the concrete manufacturing site can be saved effectively.

  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.

  For example, although aggregate, cement, and limestone fine powder are mixed as a concrete material in addition to mixing water, other materials such as fly ash and gypsum may be mixed according to the purpose.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  An example of the present invention will be described below, but the present invention is not limited to the example.

<Examples and Comparative Examples>
A concrete kneaded material having a target slump flow of 65 cm ± 5 cm was obtained by mixing for 90 seconds using a biaxial forced kneading mixer (capacity 60 L) at the ratio shown in Table 2. Specifically, Comparative Example 2, Comparative Example 4, Comparative Example 5, and Comparative Example 6 were carried out by increasing / decreasing about 5% based on the amount of water mixed in Comparative Example 1, Comparative Example 4, and Example 1, respectively. Example 2 and Example 3 were made.

  The slump flow and setting time of the obtained concrete kneaded product were measured. The slump flow test was in accordance with “Architectural Institute of Japan JASS T503”. Moreover, the setting time was measured according to “Appendix of JIS A 6204”.

<Material>
The materials we have published are listed below.
Cement: Ordinary poldoland cement (manufactured by Sumitomo Osaka Cement)
Limestone fine powder: Fine powder of limestone with a Blaine specific surface area of 5000 cm2 / g (Omi Mining)
Fine aggregate: Mixed sand from Yasugawa river sand and Yodogawa river sand (7: 3 by weight), density 2.60
Coarse aggregate: Crushed stone from Takatsuki, density 2.69
Water: Industrial water thickener 1: Methylcellulose thickener (trade name: Metroles 15000: manufactured by Shin-Etsu Chemical Co., Ltd.)
Thickener 2: Thickener containing sulfonic acid group and amidic acid group (trade name: STARVIS 4302F: manufactured by Tegusa Construction Systems)
High-performance AE water reducing agent: Polycarboxylic acid-based high-performance AE water reducing agent (trade name: Tupole HP-8: manufactured by Takemoto Yushi Co., Ltd.)
<Result>
The test results will be described with reference to Table 3.

    In Comparative Example 1, Comparative Example 2, and Comparative Example 3, if the thickener was not used, the fluidity of the concrete changed significantly due to fluctuations in the amount of water, and the target slump flow was not obtained. That is, in Comparative Example 2 in which the amount of water was reduced by about 5% compared to Comparative Example 1, the slump flow value was reduced by 10 cm or more, while in Comparative Example 3 in which the amount of water was increased by about 5% compared to Comparative Example 1. As for, the slump flow value increased by 10 cm or more, and the target slump flow value could not be obtained due to fluctuations in the amount of water.

    In Comparative Example 4, Comparative Example 5, and Comparative Example 6, when the methylcellulose thickener was used, the fluidity fluctuation was reduced, but the target value was not satisfied. Moreover, the result that the setting delay of concrete was also obtained was obtained. That is, in Comparative Example 5 in which the amount of water was reduced by about 5% compared to Comparative Example 4, the slump flow value was reduced by 5 cm or more, while the comparative example in which the amount of water was increased by about 5% relative to Comparative Example For No. 6, the slump flow value increased by 5 cm or more, and although the fluctuation in the value was smaller than in Comparative Examples 1 to 3, the target slump flow value could not be obtained due to fluctuations in the amount of water. In addition, since a methylcellulose-based thickener was used, the setting time was significantly delayed as compared with Examples 1 to 3 and Comparative Examples 1 to 3.

    In Examples 1, 2, and 3, even when the amount of water in the concrete fluctuated by a maximum of ± 5%, the fluidity of the concrete hardly changed, and no setting delay occurred. That is, in Example 2 in which the amount of water was reduced by about 5% with respect to Example 1, the slump flow value was small, but the fluctuation was 5 cm or less, while the amount of water was about 5 in comparison with Example 1. In Example 3 where the amount was increased by%, the slump flow value increased, but the fluctuation was 5 cm or less. That is, in this example, the value fluctuation was smaller than those in Comparative Examples 1 to 6 described above, and the target slump flow value could be obtained by the fluctuation of the water amount. Moreover, unlike Comparative Examples 4 to 6 using a methylcellulose-based thickener, the setting time was not significantly delayed compared to Comparative Examples 1 to 3 using no thickener.

The typical explanatory view showing the manufacturing method of the concrete concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thickener 2 ... Water reducing agent A ... Admixture.

CM ... Cement WT ... Water (total amount of water)
CZ ... Concrete material FB ... First batch CB ... Continuous batch

Claims (8)

A concrete production method comprising mixing a concrete material containing at least cement and water, a thickener containing an amino group or an amide group, and a sulfonic acid group, and a polycarboxylic acid-based water reducing agent. The method for producing concrete according to claim 1, wherein an amount of the thickener added to the cement is 0.01 to 0.2% by weight. The method for producing concrete according to claim 1 or 2, wherein a ratio between the thickener and the water reducing agent is 1:30 to 1: 200. The thickener comprises a water-soluble or water-swellable sulfo group-containing associative copolymer based on (meth) acrylamide-acrylic sulfonic acid and (meth) acrylamide or N-vinyl compound, The method for producing concrete according to 2 or 3. The method for producing concrete according to claim 4, wherein the copolymer has a number average molecular weight of 50,000 to 20,000,000. The method for producing concrete according to claim 1, 2, 3, 4, or 5, wherein the water reducing agent is a polycarboxylic acid-based high-performance AE water reducing agent. It is used by mixing with cement,
An admixture comprising a thickener containing an amino group or an amide group and a sulfonic acid group, and a polycarboxylic acid-based water reducing agent. A method for producing concrete in which a batch type mixer is used and mixing by the mixer is continuously performed in multiple batches,
As a feed material to the mixer, a thickener containing an amino group or amide group and a sulfonic acid group, a polycarboxylic acid-based water reducing agent, cement, mixing water, and an aggregate are used.
And the concrete manufacturing method characterized by making constant the quantity of the said mixing water in each batch.

Images