JPH0532447A - Ready-mixed concrete - Google Patents

Abstract

PURPOSE:To provide a fiber-reinforced concrete containing fibers mixed in a good state and capable of giving a sufficient strength, and to provide a lightweight concrete capable of being press-transported for a long distance in a good quality without generating the absorption of water in the mortar into the aggregate even when a porous lightweight aggregate is used and even when a high pressure is applied. CONSTITUTION:A ready-mixed concrete is characterized by adding beta-1,3-glucan and a high quality water-reducing agent to a cement curing agent and further adding fibers and (or) a lightweight aggregate to the mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green concrete containing β-1,3-glucan and having a high fluidity, a high filling property and a high resistance to separation, and a special material mixed therewith. is there.

[0002]

2. Description of the Related Art Techniques for fiber concrete and lightweight concrete produced by mixing fibers and lightweight aggregate with fresh concrete are already widely used.

[0003]

Problems to be Solved by the Present Invention The above-mentioned conventional techniques have the following problems. <A> In fiber concrete, fibers are concentrated in a part and form a lump (fiber ball), which does not contribute to an increase in bending, tensile strength and toughness. Therefore, it is necessary to disperse the fibers widely and uniformly, but for that purpose, it is necessary to add the fibers little by little or to perform a kneading work for a long time.
There were economically disadvantageous conditions. <B> The specific gravity differs depending on the fiber, but for this reason, the fiber having a large specific gravity sinks to the lower portion of the concrete, and the small fiber thrust floats to the upper portion, which is a problem of separation. <C> A water film was generated around the fibers due to breathing, and the water film formed a gap to reduce the adhesion between the concrete and the fiber. <D> The lightweight aggregate is porous. For this reason, in the case of conventional lightweight concrete mixed with lightweight aggregate, when pumping with a homp, water will enter the pores of the aggregate due to the pumping pressure. Therefore, the water required for the movement of concrete may be deprived from the mortar to the aggregate, which makes smooth movement difficult. <E> In order to prevent water absorption by the lightweight aggregate, it is necessary to perform water absorption treatment on the aggregate before mixing, which increases the number of steps and the amount of work. In addition, when the aggregate that absorbs water excessively is used, the pumping property is improved, but since the water in the aggregate freezes, the freeze-thaw resistance is reduced this time. <F> When pumping conventional lightweight concrete,
In order to avoid such inconvenience due to water absorption, it was necessary to reduce the pressure, and as a result, the distance that could be pumped had to be sacrificed.

[0004]

An object of the present invention is to solve the above problems, and an object of the present invention is to provide a fiber concrete in which fibers are well mixed and sufficient strength can be obtained. Further, the present invention, even if a high pressure is applied using a porous lightweight aggregate, water in the mortar is not taken away by the aggregate, it is possible to pump concrete of good quality for a long distance, lightweight concrete. The purpose is to provide.

[0005]

The present invention has been completed under the above circumstances. That is, the present invention is green concrete in which fibers and / or lightweight aggregates are mixed with green concrete containing a cement-based hardening material, β-1,3-glucan, and a superplasticizer.
Next, the raw green concrete as a base before mixing the fibers and / or the lightweight aggregate will be described. <Cement> As the cement used in the present invention,
For example, various cements represented by Portland cement containing modifying materials such as silica stone, diatomaceous earth, blast furnace slag, fly ash, and silica fume can be mentioned. The above-mentioned modifying material is an ultrafine powder, for example, a siliceous ultrafine powder such as silica fume (200,000 cm ² / g).
A more preferable effect can be obtained by using the above) together. That is, since such ultrafine powder has a large surface area because it is smaller than the size of commonly used cements by one order or more, it has a large surface area and is necessary to secure the fluidity and the filling property. It is possible to reduce the use amount of the separation reducing agent. As a result of the decrease in the amount of the separation reducing agent used, it is possible to improve the compressive strength of the finished concrete.

<Β-1,3-glucan> β-1,3-glucan is a polysaccharide in which glucose is mainly bound by β-1,3-bonds, and specifically, curdlan , Paramylon, pakiman, scleroglucan, laminaran, yeast glucan, and the like. In the present invention, curdlan is particularly preferably used. Curdlan is, for example, New Food Industry, Volume 20, Vol. 1
No. 0, pp. 49-57 (1978), mainly composed of β-1,3-glucoside bonds,
It is a polysaccharide having a heat coagulation property, that is, a polysaccharide having a property of coagulating (forming a gel) when heated in the presence of water.

Examples of such polysaccharides include polysaccharides produced by microorganisms of the genera Alcaligenes or Agrobacterium. Specifically, Alcaligenes faecalis barr Myxogenes bacterium 10C3K
Polysaccharides produced by (Agricultural Biological Chemistry (Agricultural
Biological Chemistry), No. 3
Volume 0, page 196 (1966), or Alcaligenes fuecalis bar Myxogenes bacterium 10C3K
Polysaccharide produced by the mutant strain NTK-u (IFO 13140) (Japanese Patent Publication No. 48-32673), Agrobacterium radiobactor (IFO 13127) and its variant U-19 (IFO 12126). Sugars (Japanese Patent Publication No. 48-32674) and the like can be used. Curdlan is a polysaccharide produced by a microorganism as described above, but in the present invention, it may be used as it is in an unpurified state, or if necessary, highly purified before use. May be.

Paramylon also has a β-
It is a kind of 1,3-glucan, and is a kind of storage polysaccharide accumulated in cells by a microorganism, Euglena. Such paramylon is commercially available, for example, from Carbohydrate Research.
research, 25 , 231-242 (197).
9), JP-A 64-37297 or JP-A 1-3
It is already known from Japanese Patent No. 7297. However, unlike curdlan, the powder of paramylon does not have heat coagulation, and therefore may be alkali-treated as necessary in order to have heat coagulation property. In the present invention, paramylon may be used as it is in an unpurified state, or may be highly purified before use. If β-1,3-glucan of microbial origin, particularly curdlan or paramylon is treated with an alkali described below, a divalent or higher polyvalent metal ion, for example, calcium ion, magnesium ion, copper ion, iron ion , Β-1,3-glucan having the property of forming a metal ion cross-linked gel in the presence of cobalt ions and the like can be obtained. Such a glucan capable of forming a metal ion cross-linking gel is prepared by dissolving β-1,3-glucan of microbial origin in an alkaline aqueous solution and bringing the alkaline aqueous solution into contact with a water-soluble organic solvent to form β-1,3-glucan. Glucan is precipitated, preferably p
It can be obtained by neutralizing to H6-7.

As another method for obtaining the metal ion-crosslinking gel-forming β-1,3-glucan, the alkaline aqueous solution of β-1,3-glucan is not frozen, and the frozen product is contacted with a water-soluble organic solvent. , Β-1,3-glucan is precipitated and neutralized. The glucan thus obtained is dehydrated, if necessary,
You may dry in powder form. In the above method, as the water-soluble organic solvent for precipitating glucan, alcohol such as methanol is preferably used, and as the alkaline aqueous solution for dissolving glucan, for example, sodium hydroxide, potassium hydroxide, An aqueous solution of ammonium hydroxide or the like is preferably used. The β-1,3-glucan thus obtained is, as described above,
For example, in the present invention, since it has the ability to form a metal ion cross-linked gel, it is particularly preferably used as a molding aid in a composition in which calcium ions are usually present. In the present invention, β-1,3-glucan acts as a separation reducing agent. That is, β-1,3-glucan increases the viscosity of concrete, and as a result, it is possible to prevent the fluidity of water and aggregate contained therein and the separation during pouring.

<High-performance water reducing agent> Examples of the high-performance water reducing agent used in the concrete of the present invention include those which can be used in ordinary concrete. In the present specification, the high-performance water reducing agent is used.
A water reducing agent and a fluidizing agent are included. Specific examples include naphthalene-based compounds represented by a high-condensation product of naphthalenesulfonic acid formalin, and melamine-based, carboxylic acid-based, and lignin-based compounds which are sulfonated melamine formalin condensates. These materials are used to improve the fluidity and filling properties of concrete with increased viscosity, and can reduce the water content by about twice as much as a normal water reducing agent.
Furthermore, the ready-mixed concrete used for the concrete of the present invention is simply for the purpose of reducing the amount of water, entraining an appropriate amount of air, etc.
Various admixtures may be included. For example,
Examples include AE agents, AE water reducing agents, water reducing agents, etc., and those for ordinary concrete can be used.

<Mixing Method> This concrete mixing method is not special, and a conventionally known general method can be adopted. For example, cement or aggregate is charged into a mixer, while water is mixed with various additive materials and the mixture is supplied into the mixer.

<Mixing Example> The following is an example of preferable composition of the fresh concrete which is the basis of the present invention. In the following description, the binding material refers to a mixture of cement and its modifying material. Bonding material (Portland cement,
The total amount of fly ash and blast furnace slag is 250 to 700 kg / m ³ per unit volume of concrete), and β-1,3-glucan is 0.01 to 1.0% by weight, more preferably 0.2 to 1.0% by weight, 0.2 to 6.0% by weight of high performance water reducing agent, more preferably 0.5 to
The range is 3.0% by weight. Further, when the ultrafine silica powder such as silica fume is used by substituting a part of the binding material, it is preferable that the siliceous powder in the binding material is 6 to 30% by weight. For example, the unit binding material (portrant cement, fly ash, and blast furnace slag as the total amount of concrete per unit volume of 350 ~
The unit amount of silica fume is 5 per 800 kg / m ³ ).
And 0~100kg / ^{m 3,} a beta-1,3-glucan from 0.02 to 1.0 wt%, a superplasticizer in the range of 0.5 to 3 wt%.

[0013]

[Production of Lightweight Concrete] A suitable amount of lightweight aggregate is mixed into ready-mixed concrete which is the basis of the concrete of the present invention. As the lightweight aggregate, “Asanolite” (manufactured by Nippon Cement Co., Ltd.), “Mesalite” (manufactured by Mitsui Mining & Smelting Co., Ltd.) and the like are preferable, and when these are mixed, the above concrete has extremely high separation resistance. The lightweight aggregate mixed in is uniformly dispersed inside by mixing work,
Moreover, only the aggregate does not float up. Also, when this lightweight concrete is pumped and supplied into the formwork on site, even in this pumping process,
Due to the high separation resistance, the water in the mortar is not pushed into the pores of the aggregate by the pressure, and the mortar is delivered with the water contained as originally designed until the end.

[0014]

[Manufacture of fiber concrete] An appropriate amount of fibers is mixed into the above-mentioned base concrete. The fiber can be used regardless of its specific gravity. Since the separation resistance is high when these are mixed, the fibers mixed inside are uniformly dispersed with mixing, and the fibers are not concentrated in one place. In the steps of kneading, transporting, and compacting, fibers having a large specific gravity such as steel fibers do not separate from concrete and sink downward due to high separation resistance. Alternatively, aramid fiber, vinylon fiber, etc., which have a low specific gravity, do not float above the concrete and always maintain a state of being uniformly dispersed in the concrete. For this reason, it is possible to obtain concrete having uniform quality, improved strength characteristics such as bending strength, and high toughness.

[0015]

The ready-mixed concrete, which is the basis of the concrete of the present invention, does not require compaction by a vibrating machine at the time of pouring, or even if a vibrating machine fixed to the formwork is only applied for a short time. Therefore, concrete can be easily filled into every corner of the mold without separation of aggregate. Therefore, the formwork may have a complicated shape, and the shape of the formwork is not limited by the fluidity of concrete,
In addition, it is possible to perform casting in a closed space or a wide space where the vibration device cannot reach. Since no vibration is required, the health of workers and the preservation of the environment are greatly improved. Also,
Since the material separation such as breathing does not occur even after the completion of the concrete pouring, even if the fibers and the lightweight aggregate are mixed, the dispersibility is good, and it is possible to obtain the ready-mixed concrete having the uniform quality and the high durability.

[0016]

[Experimental Example 1] The fluidity, filling property, and separation resistance of fresh concrete as the basis of the concrete of the present invention having the composition shown in Table 1 were tested.

[Table 1] In order to test the characteristics, the concrete 1 was placed in a mold 2 in which a large number of reinforcing bars 21 are arranged at a minimum interval of 35 mm as shown in FIG. The mold 2 used had a height of 500 mm, a width of 825 mm, and a slope 22 partially covering the top of the ceiling. According to this experiment, by simply pouring the concrete 1 into the mold 2, it was possible to densely fill the concrete 1 into the mold after about 99 seconds without giving any vibration. (Fig. 1-
(Fig. 4)

Next, a test was conducted to examine the strength and durability of the same composition. The resulting data is shown in Table 2.

[Table 2] The above values are equal to or higher than those of normal concrete, and no deterioration in durability was observed. The salt penetration resistance, seawater resistance, chemical resistance, neutralization resistance, etc. were sufficiently superior to those of ordinary concrete. <Comparison of Compressive Strength> The compressive strength of the concrete member manufactured without vibration was compared with the compressive strength of a general concrete member. The following two types of concrete were poured into the concrete wall formwork shown in FIG. 5, and after 28 days, core samples were taken from the positions shown in the figure and a compressive strength test was conducted. <1> Fresh concrete (fresh concrete used in the present invention) to which admixtures such as the above-mentioned separation reducing agent and high-performance water reducing agent were added was used, and no vibration was given to the fresh concrete. <2> The above admixture was not added, but vibration was applied. The results are shown in FIG. 6, and when the concrete used in the present invention was used, the compressive strength did not change at all positions of the concrete product, even though no vibration was applied, and vibration was applied. It was found that the compressive strength was higher than that of the comparative example.

[0018]

(About fineness 3250Cm ² / g) Experiment 2] In general commercially available ordinary portland cement, the following table with different ground granulated blast furnace slag (4300Cm about ² / g) and fly ash (3000 cm about ² / g) weight Concrete mixing test was carried out for the five types of the above, and slump flow was measured and filling test was performed. A U-shaped container as shown in FIG. 7 was used for the filling test. One side of this container is used as a concrete A filling chamber and the other side is used as a B measuring chamber, and communication windows are opened in the lower portions of both chambers. Reinforcing bars are provided in the communication window at intervals of 35 mm and are closed by a shutter until the start of the test. During the test, the concrete to be tested is filled in the filling chamber A, the shutter is pulled up, and the rising dimension H of the concrete to the measuring chamber B is measured and used as the criterion for determining the filling property.

The results are shown in the lower right column of Table 3, and according to the evaluation test method for the combination of the binders having such particle sizes, the unit binder for obtaining good fluidity and filling property is obtained. The minimum amount (cement + ground granulated blast furnace slag + fly ash) is 400 kg / m ³ (2
00 + 200 + 0) or more. This is intended for the filling property in the case of a multi-stage rebar with a pure rebar spacing of 35 mm, but if the pure rebar spacing is larger than this, the minimum unit binder amount is 350 kg / m. ^It can be reduced to about ³ .

[Table 3]

[0020]

[Experimental Example 3] Table 4 shows the composition and the test results when silica fume was used instead of fly ash in Experimental Example 2. In this table, the formulation No. 1 is the standard formulation. On the other hand, No. 2 to No. In No. 5, fly ash is not used at all and silica fume is used as a substitute. As a result, the required amount of binder (C + B + SF) is 4
It has been found that about 50 kg / m ³ is sufficient. This is because it has been found that with such an amount of the binder, the fluidity indicated by the slump flow is slightly lowered, while the filling property is extremely good and the filling height is sufficiently maintained.

[Table 4]

[0021]

Example 1

[Comparison of Water Absorption Rate] Next, ready-mixed concrete was produced by substituting the “aggregate” and “artificial lightweight aggregate” in the above concrete. As the artificial lightweight aggregate, for example, “Asanolite” (manufactured by Nippon Cement Co., Ltd.), “Mesalite” (manufactured by Mitsui Mining & Smelting Co., Ltd.) and the like are commercially available. In order to compare the performance of such lightweight concrete, concrete mixed with water, cement, fine aggregate, lightweight aggregate (asanolite) and high-performance water reducing agent in the ratio shown in Table 5 (Comparative Example)
Then, blast furnace slag fine powder (B), fly ash (F), and a separation reducing agent (BP) were mixed in the ratios shown in Table 5, and changes in water absorption were compared.

[Table 5] Immediately before pumping both concretes of the above mixture with a concrete pump and a certain amount of concrete after pumping,
The mortar was washed away and the artificial lightweight bone agent was taken out. Then, the weight was measured in a surface dry state. The results are shown in Table 6.

[Table 6]

[0022]

[Comparison of slump] Next, the change in slump before and after the pressure feeding was compared. The large change in slump before and after pumping means that the total amount of water has not changed, so the water in the mortar was forced to be pushed into the holes in the aggregate. It is shown. However, the lightweight concrete of the present invention has extremely good fluidity and does not maintain the mountain shape like ordinary concrete when the slump cone is lifted. Therefore, by measuring the slump flow, it was confirmed that there was no change before and after pumping. The results are shown in Table 7.

[Table 7] As is clear from Table 7, with the concrete of the present invention, even if a large pressure is applied to the concrete by pumping, the water inside the concrete is difficult to separate due to the large separation resistance, and water is taken up by the aggregate. You can see that there is no worry.

[0023]

Example 2

[Comparison of fiber dispersity] The fiber dispersity of conventional concrete containing fibers and the fiber concrete of the present invention containing fibers according to the composition shown in Table 8 was compared.

[Table 8] FIG. 8 is a graph in which the amounts of fibers mixed are changed to 1.0%, 2.0% and 3.0% and the dispersities are compared. As is clear from this figure, in the concrete of the present invention, the degree of dispersion hardly changes even when the amount of mixed fine cones increases. This indicates that the fibers are always dispersed in the concrete in a constant state.

[0024]

[Comparison of Compressive Strength] Next, the bending strength of the conventional fiber concrete and that of the present invention were compared. Both are mixed with the same amount of steel fiber at 2%, and the specimen (100 × 100
× 400 mm) was prepared. This test piece was installed horizontally, supported at intervals of 300 mm, and given a vertical load at three equal points. The resulting relationship between load and deflection is shown in FIG. From this figure, as compared with the conventional fiber reinforced concrete, it was found that the woven concrete of the present invention can bear a larger load and can withstand a large deformation.

[0025]

[Effect of lightweight concrete of the present invention] Since the lightweight concrete of the present invention has the above-mentioned structure, the following effects can be achieved. <a> It is difficult for water to separate inside the concrete because the concrete itself has high resistance to separation. Therefore, even if a large pressure is applied when concrete is pumped, water does not enter the pores of the aggregate and the water content in the mortar does not decrease. <B> Since the aggregate does not absorb much water, it is not necessary to subject the aggregate to water absorption before mixing, and it is possible to simplify the process and divert the worker to other work. Moreover, the problem of reduction in freeze-thaw resistance due to absorption of aggregate is solved. <C> Since water does not enter the pores of the aggregate, it is possible to pressurize with a large pressure and to lengthen the pumping distance. <D> Since the lightweight aggregate has a small specific gravity, it is easy for the phenomenon of separation and floating on the surface due to compaction vibration. However, since the lightweight concrete of the present invention has extremely good fluidity and large separation resistance, it can be evenly and evenly flowed into overcrowded reinforcing bars without vibration. Therefore, there is no fear of material separation due to vibration.

[0026]

[Effect of Fiber Concrete of the Present Invention] Since the fiber concrete of the present invention has the above-mentioned constitution, the following effects can be achieved. <A> Since the fiber concrete of the present invention has high separation resistance, the fibers can be uniformly dispersed inside the concrete. Therefore, it is possible to provide concrete of good quality in which defects such as fiber balls are unlikely to occur inside the concrete. <B> Since the concrete has a high resistance to separation, neither fibers having a large specific gravity nor fibers having a small specific gravity settle or float inside the concrete, and a concrete in a uniformly dispersed state can be obtained. <C> Since no breathing occurs, no breathing water gap is formed around the fiber. Therefore, the adhesion performance between fibers and concrete does not deteriorate. <D> Due to the various reasons described above, concrete having excellent strength characteristics such as bending strength and high toughness can be obtained, so that a thin member that does not use a reinforcing bar can be easily manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fluidity test of concrete used for the concrete of the present invention.

FIG. 2 is an explanatory diagram of a fluidity test of concrete used for the concrete of the present invention.

FIG. 3 is an explanatory diagram of a fluidity test of concrete used for the concrete of the present invention.

FIG. 4 is an explanatory view of a fluidity test of concrete used for the concrete of the present invention.

FIG. 5 is a diagram of a sample of a compression test.

FIG. 6 is a comparison diagram of compression tests.

FIG. 7 is an explanatory diagram of a filling test device.

FIG. 8 is a comparison diagram of the fiber dispersity of the fiber concrete of the present invention and the conventional fiber concrete.

FIG. 9 is a diagram showing the relationship between bending load and deflection amount.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C04B 14:24 2102-4G 24:22) C 2102-4G (72) Inventor Takefumi Shindo Tokyo 1-25-1 Nishishinjuku, Shinjuku-ku, Taisei Construction Co., Ltd. (72) Inventor Atsushi Sakamoto 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Somnutuku Tangtermushirikuru Tokyo 1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Taisei Corporation

Claims (1)

Claims: 1. A fresh concrete prepared by adding β-1,3-glucan and a high-performance water-reducing agent to a cement-based hardening material, and mixing fibers and / or lightweight aggregates into the fresh concrete.