JP2005281089A - Concrete composition used for shield driving direct placing method and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete composition used for a direct placing concrete lining material in a shield driving method and having excellent early strength developability and excellent water resistance. <P>SOLUTION: In the case of producing the concrete composition used for the shield driving direct placing method, an additive containing a 1st water-soluble low molecular compound (A) and a 2nd water-soluble low molecular compound (B) in addition to a chemical admixture for concrete and selected from additives each in a combination that the compound (A) and the compound (B) are respectively a compound (A) selected from ampholytic surfactants and a compound (B) selected from anionic surfactants, respectively a compound (A) selected from cationic surfactants and a compound (B) selected from anionic surfactants or respectively a compound (A) selected from cationic surfactants and a compound (B) selected from bromine compounds is blended as a thickening admixture . <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a concrete composition that is used for a direct-acting concrete lining material of a shield method, etc., and has excellent early strength and water resistance, and a method for producing the same.

As shown in FIG. 5, the excavation / lining translation method, which is one of the tunnel construction methods, uses a main cutter 12 provided on the front surface of the skin plate 11 of the shield machine 10 to form a natural ground 50 which is a spring formation. The inner mold 13, 13,... Is assembled at the rear part while excavating, and is compressed by the pressure jack 15 via the wife frame 14 between the natural ground 50 and the inner mold 13 in parallel with excavation. Concrete is cast while applying force to construct the lining concrete 16 in close contact with the natural ground 50. For the concrete used in the construction method, water resistance against groundwater is required from the time of placing. At the same time, initial strength is required.
That is, when the shield machine 10 is propelled by the propulsion jack 17, the reaction force of the shield is borne on the inner mold 13 on which the concrete is placed, so that the inner mold 13 and the cover are covered. The required concrete adhesion strength is required on the first 16 concrete surfaces. Therefore, the above concrete has water resistance and the required short-term strength (early strength). Water resistance is required.
Moreover, since the said concrete is generally pumped from the concrete pump which is not shown in figure to the concrete casting pipe 18, it needs to be excellent also in fluidity | liquidity, material separation resistance, and pump pumpability (for example, patent document 1). reference).

At present, examples of the concrete used in the above construction method include high-fluidity concrete and underwater inseparable concrete.
High-fluidity concrete adds cement chemicals, water, aggregates, and other chemical admixtures for concrete, such as high-performance AE water reducing agents, to improve fluidity, and various inorganic powders and thickeners to add material separation resistance. It is used in many areas because it can save labor during driving and eliminate the noise associated with compaction work. Especially, it is crowded with reinforcing bars. It is effective for structures that place a large amount of concrete in the formwork.
Underwater non-separable concrete increases the viscosity and water resistance of concrete by blending cement, water, and aggregate with an underwater non-separable admixture based on a water-soluble polymer based on cellulose or acrylic. In this way, even if it is directly driven into the water, the material separation is small and the reliability of quality can be improved.

On the other hand, in water-permeable concrete, which is used for vegetation concrete, drainage pavement concrete, etc., which is formed by coating coarse aggregate with cement paste, to improve adhesion and uniform shape retention to the coarse aggregate. An additive for water-permeable concrete has been proposed (see, for example, Patent Document 2).
The additive is an additive containing the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B), and is a combination of the compound (A) and the compound (B). Is (1) a combination of a compound (A) selected from amphoteric surfactants and a compound (B) selected from anionic surfactants, or (2) a compound (A) selected from cationic surfactants And a compound (B) selected from anionic aromatic compounds, and (3) a combination of a compound (A) selected from cationic surfactants and a compound (B) selected from bromine compounds. . The blending amount of the additive is appropriately selected depending on the target viscosity and the degree of uniformity of the voids. As a preferable blending amount, compound (A) is used with respect to a water-curable powder such as cement or blast furnace slag. ) And the compound (B) is 0.01 to 1% by weight, particularly preferably 0.1 to 0.5% by weight. Highly permeable concrete can be obtained.
JP 2003-327458 A JP 2002-194997 A

By the way, as described above, the shield method, in particular, the concrete composition used as the direct-acting concrete for the shield method in the spring formation, is excellent in fluidity, material separation resistance, and early strength, as well as water resistance. It is required to have excellent properties. This early strength and water resistance are properties that are difficult to achieve at the same time, and the above high fluidity concrete is excellent in fluidity and material separation resistance. Also, a chemical admixture for concrete is appropriately selected. Thus, it is possible to exert the early strength, but there is a problem with water resistance, so that it is difficult to ensure sufficient strength in driving in the groundwater pressure.
In addition, underwater inseparable concrete is excellent in fluidity and material separation resistance in addition to water resistance, but there is a problem in its early strength, so it is sufficiently early to bear the reaction force of the shield. There was a problem that strength could not be obtained.

  The present invention has been made in view of conventional problems, and is used for a direct-acting concrete lining material of a shield method, etc., and a concrete composition excellent in early strength and water resistance and a method for producing the same The purpose is to provide.

As a result of intensive studies, the present inventors have determined that, in addition to the chemical admixture for concrete, in addition to the chemical admixture for concrete, the concrete composition using fine aggregate and coarse aggregate as aggregate. By adding the above-mentioned additive for water-permeable concrete, which exhibits an excellent effect as a thickening additive, it has excellent early strength, fluidity, and material separation resistance, and is contrary to the above-mentioned early strength. It has been found that a concrete composition having excellent water resistance can be obtained, and the present invention has been achieved.
That is, the invention according to claim 1 of the present invention is a cement, water, fine aggregate, coarse bone used for direct casting concrete of the lining concrete direct casting method (hereinafter referred to as shield directing method) in the shield method. A concrete composition obtained by adding and kneading a chemical admixture for concrete and a thickening admixture to a material, wherein the first water-soluble low-molecular compound (A) and the second water-soluble are used as the thickening admixture. An additive containing a low molecular compound (B), wherein the compound (A) and the compound (B) are selected from a compound (A) selected from amphoteric surfactants and an anionic surfactant ( B), or a combination of a compound (A) selected from a cationic surfactant and a compound (B) selected from an anionic aromatic compound, or a cationic surfactant It is characterized in that that combination of compounds (A) and a compound selected from bromine compound (B), with either the additive of the additive selected from.
The invention described in claim 2 is characterized in that, in the concrete composition used in the shield direct striking method according to claim 1, the proportion of fine aggregate contained in the aggregate is 30 to 45%. Is.
The invention according to claim 3 is characterized in that, in the concrete composition used in the shield direct striking method according to claim 1 or 2, the water cement ratio in the concrete composition is 30 to 40%. To do.

Further, in the concrete composition used in the shield direct striking method according to any one of claims 1 to 3, the invention described in claim 4 is selected from cationic surfactants as the thickening admixture. The compound (A) and the admixture containing the compound (B) selected from the anionic aromatic compounds are used, and the above compound (A) and the above compound (B) are each added in an amount of 0. It is blended at a ratio of 5 to 5.0% by weight.
The invention according to claim 5 is a concrete composition used in the shield direct striking method according to any one of claims 1 to 4, wherein a carboxyl group-containing polyether water reducing agent is used as the concrete chemical admixture. And the above water reducing agent is blended at a ratio of 0.5 to 5.0% by weight with respect to the cement.

  A sixth aspect of the present invention is a method for producing a concrete composition used in the shield direct striking method according to any one of the first to fifth aspects, wherein the chemical admixture for concrete is used for cement, water and aggregate. And the second water-soluble low molecular weight compound (B) are added and kneaded, and then the first water-soluble low molecular weight compound (A) is added to the kneaded product and kneaded again to form the concrete composition. It is characterized in that a product is manufactured.

According to the present invention, the first water-soluble low molecular weight compound (A) and the second water-soluble low molecular weight are added in addition to the chemical admixture for concrete when producing the concrete composition used in the shield direct-fired construction method. Compound (B), an additive containing compound (B), wherein compound (A) and compound (B) are selected from amphoteric surfactants (A) and anionic surfactants Or a combination of a compound (A) selected from a cationic surfactant and a compound (B) selected from an anionic aromatic compound, a compound (A) selected from a cationic surfactant and a bromine compound In combination with the compound (B) selected from the above, any one of the additives selected from the above is blended as a thickening admixture, so that it has excellent early strength, fluidity, and material separation resistance. Both can be obtained concrete compositions used in excellent shielding straight out method in water resistance.
At this time, early strength and water resistance can be further improved by setting the proportion of fine aggregate contained in the aggregate to 30 to 45% and the water cement ratio to 30 to 40%.

Further, as the thickening additive, an additive containing a compound (A) selected from a cationic surfactant and a compound (B) selected from an anionic aromatic compound is used, and the compound (A) By blending the compound (B) at a ratio of 0.5 to 5.0% by weight with respect to the unit water amount, the early strength and water resistance can be reliably improved.
Further, when the concrete composition is produced, the chemical admixture for concrete and the second water-soluble low-molecular compound (B) are added to and kneaded with cement, water, and aggregate, and then the kneaded product. The first water-soluble low-molecular compound (A) is added to the mixture and kneaded again to produce a concrete composition. Therefore, the concrete composition used in the shield direct-working method can be efficiently produced. .

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an outline of a method for producing a concrete composition used in a shield direct-fired construction method according to the best mode of the present invention. The concrete composition of the present invention comprises cement, water, coarse aggregate, and fine bone. A chemical admixture for concrete is added to the material, and a second water-soluble low molecular weight compound (A) selected from cationic surfactants and a second anionic aromatic compound are selected as thickening admixtures. The water-soluble low molecular weight compound (B) and a thickening admixture are used. The production method is as follows. First, in the mixer 1 of the concrete plant A, cement, water, fine aggregate, concrete After kneading the chemical admixture for use and the second water-soluble low-molecular compound (B), the first water-soluble low-molecular compound (A) is added to the kneaded product and kneaded again. Add coarse aggregate to and mix Making concrete composition was. The kneaded kneaded material is loaded on the truck agitator 3 of the transport vehicle 2 and conveyed to the construction site B while being kneaded, unloaded, loaded into a concrete pump (not shown), and the concrete shown in FIG. The lining concrete 16 is constructed by being pumped to a concrete placing pipe 18 connected to a pressure jack 15 for placing.
The above-mentioned cement is not particularly limited, and Portland cement such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, white Portland cement such as limestone, clay and iron oxide, blast furnace cement, Although mixed cements such as fly ash cement and silica cement can be used, it is particularly preferable to use early-strength Portland cement.
At this time, the water cement ratio (W / C) is preferably 30 to 40%, particularly preferably around 35%. If the water-cement ratio is less than 30%, not only the viscosity increases and the fluidity decreases, but also the proportion of cement increases, so the hydration heat generation increases and temperature cracking is likely to occur. If it exceeds 40%, it is necessary to add the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound (B) in order to obtain the same viscosity. Since early strength will fall, it is preferable to set it as 30 to 40%.

In order to improve fluidity, material separation resistance, and pumpability, the fine aggregate ratio (S), which is the ratio of fine aggregate contained in the aggregate (coarse aggregate and fine aggregate). / A) is preferably (S / a) = 30 to 45%. When the fine aggregate ratio is less than 30% or exceeds 45%, the viscosity of the cement paste decreases and the water resistance decreases.
In addition, when coarse aggregate with a large diameter is used as the coarse aggregate, the unit water volume for obtaining the required slump is small and economical, but the maximum dimensions are as follows: rebar spacing, cover thickness It is necessary to consider this. In addition, if the maximum dimension is excessive, it will be difficult to handle the concrete, the material will be easily separated, and the pumpability will be reduced, so the maximum dimension of the coarse aggregate will not be excessive. It is necessary to consider. For example, under the condition of pressure feeding with 3 inch piping, the water cement ratio is set to 40% or less, the maximum size of the coarse aggregate is set to about 13 mm, and the ratio of fine aggregate (S / a) is set lower than before. By doing so, it is possible to produce concrete having high strength while ensuring high fluidity, pumpability and material separation resistance.
The fine aggregate is an aggregate that passes through all of the 10 mm mesh sieve and passes through the 5 mm mesh sieve by 85% by weight or more, and the coarse aggregate is an aggregate that does not pass through the 5 mm mesh sieve by more than 85% by weight. In general, all are obtained from river sand, sea sand, mountain sand, crushed stone and the like.
In addition, the concrete chemical admixtures such as lignin-based, polycarboxylic acid-based, melamine-based, naphthalene-based, or aminosulfonic acid-based polyether water reducing agents, AE water reducing agents, high-performance AE water reducing agents, etc. It can be appropriately selected from the commonly used chemical admixtures for concrete. Among them, the carboxyl group-containing polyether water reducing agent having excellent compatibility with the thickening admixture is preferably in a proportion of 0.5 to 5.0% by weight, particularly preferably 1 with respect to the early strong cement. By blending at a ratio of 0.0 to 5.0% by weight, early strength can be surely expressed.

The first water-soluble low molecular weight compound (A) used in the present invention is preferably a quaternary ammonium salt type cationic surfactant, and particularly preferably an additive mainly composed of an alkyl ammonium salt. The second water-soluble low molecular weight compound (B) is preferably a sulfonate having an aromatic ring, and particularly preferably an additive having an alkylallyl sulfonate as a main component. Examples of the low molecular compound (A) and the second water-soluble low molecular compound (B) include a compound (A) selected from amphoteric surfactants such as amidopropyl betaine dodecanoate and POE (3) dodecyl ether sulfate. Or a combination of a compound (A) selected from the above cationic surfactants and a compound (B) selected from bromine compounds such as sodium bromide It may be.
In this example, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are blended at a ratio of 0.5 to 5.0% by weight with respect to the unit water amount. At the same time, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are mixed in the cement at a certain ratio.
Further, the underwater non-separable material (admixture) used in the conventional underwater non-separable concrete causes a set delay because the thickening adsorbent adsorbs to the cement particles. When (A) and the second water-soluble low-molecular compound (B) are mixed in the cement at a certain ratio (for example, in the range of 2: 5 to 5: 2), the first water-soluble low-molecular compound (B) is mixed. Since the molecular compound (A) and the second water-soluble low molecular compound (B) are electrically arranged to form a pseudo polymer and exert a thickening function, the cement particles are not affected. Does not cause curing delay.
Therefore, it is possible to obtain a concrete composition which is optimally used as concrete for the shield direct striking method and has excellent early strength and excellent water resistance. As a result of the experiment, the mixing ratio of the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound (B) was optimum when the ratio was 1: 1.

In kneading, first, cement group, water, fine aggregate, a carboxyl group-containing polyether water reducing agent that is a chemical admixture for concrete, and an alkyl allyl sulfonic acid that is the second water-soluble low molecular compound (B). Sodium is added and kneaded to prepare a kneaded product. Thereafter, the kneaded product is added with an alkylammonium salt which is the first water-soluble low-molecular compound (A) and kneaded again, and finally coarse bone. It is preferable to add a material and knead to produce a concrete composition.
This is because when the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound (B) are added simultaneously, the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound (B) are added. Since a pseudo polymer is formed in an inhomogeneous state with the water-soluble low molecular weight compound (B), a long time of kneading is required to obtain the desired characteristics by forming the pseudo polymer in a homogeneous state. It is to become.
In addition, when the first water-soluble low molecular weight compound (A) is added first, bubbles are generated during kneading and the amount of air in the concrete increases, which may cause a decrease in strength, a decrease in specific gravity, or the like. .

  The concrete composition thus obtained not only has excellent early strength and fluidity, but also has excellent water resistance. Since sufficient strength and water resistance can be ensured, it has sufficient characteristics as a direct-acting concrete lining material for the shield construction method in spring ground formations. In addition, since it has excellent pumping ability and material separation resistance, it can also be sent by a 3-inch pipe in the pit.

  In the above-mentioned best mode, the case where the concrete composition is used with a direct-acting concrete lining material of the shield construction method has been described, but the present invention is not limited to this, and according to a vibrator that has conventionally used high-fluidity concrete. The concrete composition of the present invention is also suitable for construction of buildings that are difficult to compact, and for concrete construction where water is present such as offshore structures and underground structures, which conventionally used underwater non-separable concrete. Is fully applicable.

In the above example, the second water-soluble low-molecular compound (B) such as cement, water, fine aggregate, concrete chemical admixture, and sodium alkylallylsulfonate is kneaded in the mixer of the concrete plant. Furthermore, after adding the first water-soluble low molecular weight compound (A) to the kneaded product and kneading again, finally, coarse aggregate was added and kneaded, and the kneaded product was transported to the construction site B. 2A, in the mixer 1 of the concrete plant A, cement, water, fine aggregate, coarse aggregate, concrete chemical admixture, and the second water-soluble low molecular weight compound. After kneading (B), the kneaded material is loaded on the truck agitator 3 of the transport vehicle 2 and transported to the construction site B while stirring at a low speed. At the construction site B, the first water-soluble substance is added to the kneaded material. Low molecular compound (A) Pressurized to, it may be by high-speed stirring at the track agitator 3 producing a concrete composition.
Alternatively, as shown in FIG. 2 (b), cement, water, fine aggregate, coarse aggregate, and a chemical admixture for concrete are kneaded in the mixer 1 of the concrete plant A, and this kneaded product is mixed with the transport vehicle 2. After being loaded on the track agitator 3 and transported to the construction site B while stirring at a low speed, the second water-soluble low molecular weight compound (B) was added at the construction site B and stirred at a high speed with the track agitator 3, followed by the kneading. The above-mentioned concrete composition may be produced by adding the first water-soluble low-molecular compound (A) to a product and further stirring at high speed.

As shown in the tables of FIGS. 3 (a) and 3 (b), an early strong cement (density: 3.14 g / cm ³ ) 543 kg / m ³ is added to water 190 kg / m ³ , resulting in a water cement ratio of 35%. After adjustment as described above, the main component is a high-performance special admixture (manufactured by Kao Corporation, carboxyl group-containing polyether water reducing agent, trade name “Mighty 4000FA”), sodium alkylallylsulfonate. Additives (trade name “Visco Top 100FA”, manufactured by Kao Corporation) are added, and 597 kg / m ³ of fine aggregate (density: 2.63 g / cm ³ ) obtained from river sand is added and kneaded. Then, an additive containing an alkylammonium salt as a main component (trade name “Visco Top 100FB” manufactured by Kao Corporation) is added to this kneaded product and kneaded again, and finally coarse aggregate (density: 2.56 g / cm ³⁾ kneading Conch added 597kg / m ³ It was produced over preparative composition. At this time, a coarse aggregate having a size of 13 mm or less was used as the coarse aggregate.
The following material tests were conducted on the above concrete composition, and the results of comparing the properties with conventional high-fluidity concrete and underwater concrete are shown in the table of FIG.
The high-fluidity concrete used for comparison was prepared based on the “High-fluidity concrete construction guidelines”, and the underwater concrete was fabricated based on the “underwater inseparable concrete design and construction guidelines (draft)”.
(1) Initial properties: slump flow test (5 minutes, 10 minutes), air volume test, concrete temperature (2) retention of fresh concrete over time; initial property test items are refined 0,60
120, 180, 240 minutes.
(3) Inseparability in water; drop fresh concrete into water and measure pH (4) Water tightness; create a cylindrical specimen of fresh concrete and apply water pressure to the specimen
Measure the amount of permeated water and conduct a strength test (5) Viscosity test; Pour concrete on an inclined surface of 23 degrees and measure its speed (6) Compressive strength test; Perform according to JIS A 1108 (7) Pump pumping test; confirming pumpability with 3 inch pipe (measurement of pressure loss in pipe, concrete
Confirmation of pressure loss
(8) Measurement of shrinkage; measurement of shrinkage by length change test As is apparent from the table of FIG. 4, the concrete composition of the present invention is excellent in fluidity, material separation resistance, and early strength. In addition to this, it was confirmed that it has excellent water resistance.

  As described above, according to the present invention, it is possible to obtain a concrete composition that is excellent in early strength and water resistance, as well as excellent in pumpability and material resistance. Construction of lining concrete in buildings, construction of buildings that are difficult to compact with vibrators, and concrete construction in places where water such as offshore structures and underground structures exist easily and reliably Can do.

It is a figure which shows the outline | summary of the manufacturing method of the concrete composition used for the shield direct striking method which concerns on the best form of this invention. It is a figure which shows the other manufacturing method of the concrete composition by this invention. It is a table | surface which shows the use material and mixing | blending of the concrete composition of an Example. It is the table | surface which compared the characteristic of the concrete composition used for the shield direct striking method in the Example of this invention, and the conventional high fluidity concrete and underwater concrete. It is a figure which shows an example of the conventional excavation and lining translation method.

Explanation of symbols

10 shield machine, 11 skin plate, 12 main cutter, 13 inner formwork, 14 end frame, 15 pressure jack, 16 lining concrete, 17 propulsion jack,
50 Jiyama.

Claims (6)

  A concrete composition used in direct-acting concrete for shield construction, which is made by adding a chemical admixture for concrete and a thickening admixture to cement, water, fine aggregate, and coarse aggregate and kneading them. An additive containing the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) as an admixture, wherein the compound (A) and the compound (B) are amphoteric A combination of a compound (A) selected from a surfactant and a compound (B) selected from an anionic surfactant, or a compound (A) selected from a cationic surfactant and an anionic aromatic compound Addition of any of additives selected from a combination with a compound (B), a combination of a compound (A) selected from cationic surfactants and a compound (B) selected from a bromine compound Shield straight out concrete composition for use in method, characterized by using.   The proportion of fine aggregate contained in the aggregate is 30 to 45%, and the concrete composition used for the shield direct striking method according to claim 1.   The concrete composition used for the shield direct striking method according to claim 1 or 2, wherein a water cement ratio in the concrete composition is 30 to 40%.   As the thickening admixture, a thickening admixture containing a compound (A) selected from cationic surfactants and a compound (B) selected from anionic aromatic compounds is used, and the compound (A) and the above are used. Compound (B) was blended at a ratio of 0.5 to 5.0% by weight with respect to the unit water amount, respectively, and the shield direct striking method according to any one of claims 1 to 3 Concrete composition used for   A carboxyl group-containing polyether water reducing agent is used as the chemical admixture for concrete, and the water reducing agent is blended in a proportion of 0.5 to 5.0% by weight with respect to cement. The concrete composition used for the shield direct striking method in any one of Claims 1-4. It is a method of manufacturing the concrete composition used for the shield direct striking method according to any one of claims 1 to 5, comprising cement, water, aggregate, a chemical admixture for concrete, and the second After adding and kneading the water-soluble low-molecular compound (B), the first water-soluble low-molecular compound (A) is added to the kneaded product and kneaded again to produce the concrete composition. The manufacturing method of the concrete composition used for the shield direct striking method characterized by having performed.

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