WO2005095300A1 - Concrete composition, process for producing the same, method of regulating viscosity, and method of constructing cast-in-place concrete pile from the concrete composition - Google Patents

Abstract

In producing a concrete composition by adding a thickening admixture to cement, water, and an aggregate and kneading them, use is made as the thickening admixture of an additive which comprises a first water-soluble low-molecular compound (A) and a second water-soluble low-molecular compound (B) and which is an additive selected among additives in which the combinations of the compounds (A) and (B) respectively are: a combination of a compound (A) selected among amphoteric surfactants and a compound (B) selected among anionic surfactants; a combination of a compound (A) selected among cationic surfactants and a compound (B) selected among anionic aromatic compounds; and a combination of a compound (A) selected among cationic surfactants and a compound (B) selected among boron compounds. Thus, a concrete composition can be obtained which is usable for, e.g., an extruded concrete lining material in the shield tunneling technique and is excellent not only in early strength but in water resistance.

Description

 Specification

 Concrete composition, method for producing the same, method for adjusting viscosity, and method for constructing cast-in-place concrete pile using this concrete composition

 Technical field

 [0001] The present invention provides a concrete composition having excellent early strength, fluidity, and material separation resistance, and also having excellent water resistance and cell leveling properties, a method for producing the same, a method for adjusting the viscosity thereof, and The present invention relates to a method for constructing a cast-in-place concrete pile using the concrete composition.

 Background art

 [0002] In the tunneling method, which is one of the tunneling methods, the excavation translation method uses a main cutter 32 provided in front of a skin plate 31 of a shield machine 30, as shown in FIG. While assembling the inner formwork 33, 33, ... at the rear, a pressure jack 35 is inserted between the ground 40 and the above-mentioned inner formwork 33 via the spike form 34 in parallel with the excavation. The concrete is poured while the compressive force is reduced, and the covering concrete 36 is built in close contact with the ground 40, and the concrete used in the above method requires early strength after casting. In particular, when the ground 40 is a spring formation, water resistance to groundwater is required (for example, see Patent Document 1).

 That is, when the shield excavator 30 is propelled by the propulsion jack 37, the reaction force of the shield is borne by the inner form 33 on which the concrete is cast. The required adhesive strength is required even in the early stage of casting between the above-mentioned 36 concrete covers and the early stage of casting. Therefore, the concrete has the required short-term strength (early strength) and The concrete is required to be water-resistant to satisfy the target strength by casting.In general, the above concrete is pumped from a concrete pump (not shown) to a concrete casting pipe 38 through a pipe of about 3 inches in diameter. Therefore, it is necessary to have excellent fluidity, resistance to material separation, and pumpability.

[0003] At present, concrete used in the above-mentioned construction methods includes, for example, high-fluidity concrete. Concrete and underwater non-separable concrete.

 High-fluidity concrete is concrete with excellent early-strength, fluidity, and material separation resistance that can be reliably filled into formwork without compaction by vibrators. A concrete admixture such as a high-performance AE water reducing agent is added to increase the fluidity, and various inorganic powders and thickeners are added to improve the material separation resistance.

 On the other hand, underwater non-separable concrete used for construction of marine structures and underwater tunnels is based on water, non-separable admixture of cement, water, and aggregates containing cellulose-based or acrylic water-soluble polymers as a main component. By mixing the agent, the viscosity and water resistance of the concrete are increased, and even if the concrete is directly poured into water, the material separation is small and the reliability of quality can be improved.

 On the other hand, in permeable concrete, which is used for vegetation concrete and concrete for drainage pavement, etc., which is formed by dusting coarse aggregate with a cement paste, the adhesion to the above-mentioned coarse aggregate and uniform shape retention are achieved. There has been proposed an additive for permeable concrete for improving the properties (for example, see Patent Document 2).

 The additive is an additive containing a first water-soluble low-molecular compound (A) and a second water-soluble low-molecular compound (B), and contains the compound (A) and the compound (B). Examples of the combination include (1) a combination of a compound selected from amphoteric surfactants (A) and a compound (B) selected from an amphoteric surfactant, or (2) a cationic surfactant. Combination of selected compound (A) and compound (B) selected from anionic aromatic compounds, (3) compound selected from cationic surfactant (A) and compound selected from bromine compound ( Combination with B). The compounding amount of the above additives is appropriately selected depending on the desired degree of viscosity and uniformity of the voids, but a preferable compounding amount is cement! /, For water-hardening powder such as blast furnace slag. Thus, the sum of the compound (A) and the compound (B) is 0.01 to 1% by weight, particularly preferably 0.1 to 0.5% by weight, whereby the porosity is 20 to 30%. Highly permeable concrete including continuous voids can be obtained.

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-327458 Patent Document 2: Japanese Patent Application Laid-Open No. 2003-327458

 Disclosure of the invention

 Problems to be solved by the invention

 [0005] By the way, concrete compositions used as shield concrete, especially as direct-casting concrete in shield construction in a spring formation, are excellent in early strength, fluidity, and material separation resistance as described above. In addition, it is required to have excellent water resistance. The high strength and the water resistance are characteristics that are difficult to achieve in the past, and the high fluidity concrete has excellent fluidity and material separation resistance, and a chemical admixture for concrete is appropriately selected. For example, the cement can be washed out at the time of driving under ground water pressure, and sufficient function as concrete can be secured. It was difficult.

 In addition, underwater non-separable concrete is excellent in fluidity and material separation resistance in addition to water resistance.Since it has a problem with early strength, it has sufficient initial strength to bear the reaction force of the shield. There was a problem that was not obtained.

 [0006] In view of the above, a high fluidity water resistant material which has both the early strength of the high fluidity concrete and the water resistance of the non-separable concrete in water and has excellent fluidity, material separation resistance and self-leveling property. The development of concrete compositions is desired.

 If a highly fluidized water-resistant concrete composition as described above can be obtained, concrete piles should be installed not only in direct-cast concrete using shield method, construction of offshore structures, underwater tunnels, etc., but also in places where there is underground water or confined groundwater. It can also be used when building.

 [0007] The present invention has been made in view of the above-mentioned conventional problems, and is a concrete composition having excellent early strength, fluidity, and resistance to material separation, and also having excellent water resistance and self-leveling properties. It is an object of the present invention to provide a method for producing the same, a method for adjusting the viscosity thereof, and a method for constructing a cast-in-place concrete pile using the concrete composition.

 Means for solving the problem

[0008] The present inventors have conducted intensive studies and as a result, have found that the above-mentioned water-permeable concrete, which exhibits an excellent effect of adhering to the above-mentioned aggregate and uniform shape retention, as a thickening admixture in a concrete composition. Incorporation of additives for heat resistance provides excellent early strength, fluidity, and resistance to material separation. In addition, it has been found that a concrete composition excellent in water resistance, which is a property contrary to the above-mentioned early strength, can be obtained, and the present invention has been accomplished.

 That is, the invention described in claim 1 of the present application is a concrete thread and a kneaded product obtained by adding a thickening admixture to cement, water, and aggregate, and the first thickening admixture is used as the first thickening admixture. An additive containing a water-soluble low-molecular compound (A) and a second water-soluble low-molecular compound (B), wherein the compound (A) and the compound (B) are also selected for their amphoteric surfactant power. Compound (A) and ionic surfactant A combination of the selected compound (B), or a compound selected from cationic surfactants (A) and ionic aromatic compounds The additive selected from the combination of the selected compound (B) and the cationic surfactant is selected from the combination of the selected compound (A) and the compound (B) selected from the brominated compound. It is characterized by using one of the additives.

[0009] The invention according to claim 2 is the concrete composition according to claim 1, wherein the thickening admixture is a compound (A) selected from a cationic surfactant and an aionic aromatic compound. The compound (A) and the compound (B) are each used in an amount of 0.5 to 5.0% by weight, based on the unit water amount, while using an admixture containing a compound (B) selected from group III compounds. In the ratio of

 The invention described in claim 3 is the concrete thread according to claim 1 or claim 2, wherein the ratio of water cement in the concrete thread is 30 to 60%. is there.

 The invention according to claim 4 provides the concrete composition according to any one of claims 1 to 3, wherein the concrete composition further comprises a concrete admixture for cement with respect to cement. , 0.5 to 5.0% by weight.

 The invention according to claim 5 is the concrete composition according to claim 4, wherein a carboxyl group-containing polyether-based water reducing agent is used as the chemical admixture for concrete.

[0010] The invention according to claim 6 provides the concrete composition according to any one of claims 1 to 5, wherein the aggregate comprises coarse aggregate and fine aggregate. The ratio of fine aggregate, which is the ratio of fine aggregate contained in the aggregate, is 30-45%. Things.

 Further, the invention according to claim 7 is the concrete composition according to any one of claims 1 to 5, wherein at least a part or all of the aggregate has a specific gravity smaller than that of the ordinary aggregate. It is characterized in that one or both of aggregate and aggregate having specific gravity larger than that of ordinary aggregate are used.

 The invention according to claim 8 is a method for producing the concrete composition according to any one of claims 1 to 7, wherein the second water-soluble material is used for cement, water, and aggregate. After adding and kneading the molecular compound (B), the first water-soluble low-molecular-weight compound (A) is added to the kneaded material, and the mixture is kneaded again to produce the concrete composition. And

 Further, the invention according to claim 9 is a method for adjusting the viscosity of the concrete composition according to any one of claims 1 to 7, wherein the concrete composition further comprises: The viscosity of the concrete composition is adjusted by adding one or both of the water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B). And

 According to a tenth aspect of the present invention, in the method for adjusting the viscosity of the concrete composition according to the ninth aspect, the initial compounding ratio of the compound (A) and the compound (B) is set to approximately 1: 1. It is characterized by.

 The invention according to claim 11 provides the concrete composition according to claim 9 or claim 10, wherein the viscosity of the concrete composition is lower than the viscosity at the time of production. In this case, the first water-soluble low molecular compound (A) is added to the concrete composition.

 The invention according to claim 12 provides a method for adjusting the viscosity of a concrete composition according to claim 9 or claim 10, wherein the viscosity of the concrete composition at the casting site is determined at the time of production. When the viscosity is higher than the viscosity of the concrete composition, the second water-soluble low molecular weight compound (B) is added to the concrete composition.

The invention described in claim 13 is a method for adjusting the viscosity of a concrete composition according to any one of claims 9 to 12, wherein the concrete composition is concreted. In the case of placing by pumping with a water pump, the first water-soluble low molecular weight compound (A) is previously added to the concrete composition, and the force is also pumped.

[0012] Further, according to the invention set forth in claim 14, a steel bar is inserted into a hole from which the ground is excavated, and a concrete composition is pumped into the hole by passing a concrete composition through a tremy tube. In the method for constructing a cast-in-place concrete pile, the concrete composition according to any one of claims 1 to 6 is used as the concrete composition.

 The invention according to claim 15 provides a method for constructing a cast-in-place concrete pile according to claim 14, wherein first, the concrete containing the thickening admixture is poured to a predetermined depth, It is characterized by the fact that concrete piles are constructed by mixing concrete with the above thickening admixtures. The invention's effect

 According to the present invention, when a concrete composition is produced, the first water-soluble low-molecular compound (A) selected from cationic surfactants is used as an additive to be added as a thickening admixture. ) And a second water-soluble low-molecular-weight compound (B) selected from anionic aromatic compounds, such as an additive. Concrete composition with excellent strength, fluidity, and material separation resistance, and excellent water resistance and self-leveling properties in a wide range of water-cement ratio of 30 to 60%. Can be obtained.

 At this time, the thickening admixture is a cationic surfactant having a compound selected from the group consisting of a compound (A) and a compound selected from an anionic aromatic compound (B). If the compound (B) and the compound (B) are blended at a ratio of 0.5 to 5.0% by weight with respect to the unit water amount, the fluidity, the early strength, and the water resistance can be further improved. The concrete composition is further mixed with a chemical admixture for concrete, such as a lipoxyl group-containing polyether-based water reducing agent, having excellent compatibility with the viscosity increasing admixture, in an amount of 0.5 to 5.0 with respect to cement. If it is blended in a ratio of weight%, fluidity and early strength can be surely developed.

[0014] Further, coarse aggregates and fine aggregates are used as the aggregates, and fine aggregates contained in the aggregates are used. If the proportion of the material is 30 to 45%, concrete composition that is excellent in early strength and water resistance and excellent in pumpability, which is suitable for shield method, especially shield direct-casting method in spring water formation Things can be manufactured.

 Furthermore, at least a part or all of the aggregate has a large difference in specific gravity from ordinary aggregate, such as a lightweight aggregate having a smaller specific gravity than ordinary aggregate and a heavy aggregate having a specific gravity greater than ordinary aggregate. Even when using aggregates of different specific gravity that can be easily separated from each other, it is possible to uniformly disperse the aggregate of different specific gravity in concrete, so construct a concrete structure in which aggregate of different specific gravity is evenly dispersed. Can be.

[0015] Further, in producing the concrete composition, the second water-soluble low-molecular-weight compound (B) is added to cement, water, and aggregate and kneaded, and then the first kneaded product is added to the kneaded material. Since the concrete composition is produced by adding the water-soluble low molecular compound (A) and kneading again, the concrete composition can be produced efficiently.

 When adjusting the viscosity of the concrete composition, the first water-soluble low-molecular compound (A) and the second water-soluble Since the viscosity of the concrete composition is adjusted by adding one or both of the molecular compound (B), the concrete yarn can be easily formed without affecting the properties of the concrete composition. Further, the viscosity of the composition can be adjusted to a predetermined viscosity.

[0016] Further, the concrete composition of the present invention is excellent in self-leveling as well as in flowability and water resistance. Therefore, it is possible to construct a cast-in-place concrete pile using this concrete composition. In addition, muddy water at the time of concrete pouring can be greatly reduced, such as sedimentation of the perforated wall. Even if there is, a highly reliable concrete pile can be constructed. At this time, first, a concrete containing the above-mentioned thickening admixture is poured into the concrete to a predetermined depth, and then the above-mentioned thickening admixture is added, and! /! Concrete is poured and a concrete pile is constructed. By doing so, the amount of expensive concrete mixed with the thickening admixture can be reduced, and the material cost can be significantly reduced. Brief Description of Drawings FIG. 1 is a diagram showing an outline of a method for producing a concrete composition used in a shield direct driving method according to a second preferred embodiment of the present invention.

 FIG. 2 is a view showing another method for producing the concrete composition of the present invention.

 FIG. 3 is a flowchart showing a method for adjusting the viscosity of a concrete composition according to the present invention.

 FIG. 4 is a construction diagram of a concrete pile by an earth drill method.

 FIG. 5 is a view showing a method of constructing a cast-in-place concrete pile according to a third preferred embodiment of the present invention.

 FIG. 6 is a diagram showing an example of a conventional excavation translation method.

 Explanation of symbols

 [0018] 1 mixer, 2 transport vehicle, 3 truck agitator,

 10 concrete piles, 10k extra,

 11 High self-leveling waterproof concrete, 12 Normal concrete,

 20 ground, 21 earth drill, 22 stabilizing liquid, 23 drill hole,

 24 rebar baskets, 25 tremy tubes, 30 shield machine,

 31 skin plate, 32 main cutter, 33 inner formwork, 34 wife frame,

 35 caro pressure jack, 36 lining concrete, 37 propulsion jack,

 40 Ground, A concrete plant, B construction site.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode of the present invention will be described.

 Best mode 1.

BEST MODE FOR CARRYING OUT THE INVENTION The concrete composition according to the best mode 1 of the present invention comprises a high-strength Portland cement, water, coarse aggregate, and fine aggregate mixed with a chemical admixture for concrete, and a cationic interface admixture as a thickening admixture. A blend of an admixture containing a first water-soluble low-molecular compound (A) whose activator power is also selected and a second water-soluble low-molecular compound (B) selected from an ionic aromatic compound First, a kneaded product was prepared by kneading a chemical admixture for concrete and the second water-soluble low-molecular-weight compound (B) into cement, water, and fine aggregate. Then, the first water-soluble low-molecular compound (A) is added to the kneaded material, and the mixture is kneaded again. Finally, coarse aggregate is added and kneaded to obtain a concrete composition. At this time, the water cement ratio (WZC) is preferably set to 30 to 60%. If the water cement ratio is less than 30%, the viscosity increases, the fluidity is reduced, and the proportion of cement is increased. As a result, the heat of hydration increases, and temperature cracks are more likely to occur. If the content exceeds 60%, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) need to be added in order to obtain the same viscosity. Since the early strength is reduced, the content is preferably 30 to 60%, more preferably 30 to 40%, and particularly preferably about 35%.

 The fine aggregate is an aggregate that passes through all the 10 mm screen sieves and passes through 85 mm% or more of the 5 mm screen sieve, and the coarse aggregate is an aggregate that does not pass through 85 mm% or more through the 5 mm screen sieve. In this case, in this example, the power using the river sand power is also used. The sea sand, mountain sand, crushed stone, etc. may be used.

 As the first water-soluble low molecular weight compound (A) used in the present invention, a quaternary ammonium salt type cationic surfactant is preferred, and an alkyl ammonium salt as a main component is particularly preferred. Additives are preferred. Further, as the second water-soluble low molecular weight compound (B), a sulfonate having an aromatic ring is preferred, and in particular, an additive mainly containing an alkylaryl sulfonate is preferred! /, The first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are selected from amphoteric surfactants such as amidopropyl betaine dodecanoate (A) and POE. (3) Combination of a compound (B) selected from an aionic surfactant such as dodecyl ether sulfate, or a compound (A) selected from the above cationic surfactants and a bromine compound such as sodium bromide It may be a combination with the compound (B) selected from!

By the way, when the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are mixed into cement at a certain ratio, the first water-soluble low-molecular compound (A) When the water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are electrically arranged to form a pseudopolymer, the admixture functions as a thickener and the concrete Ability to improve the early strength and fresh retention of the composition For this purpose, as described above, the second water-soluble low molecular weight compound (B) is first added and kneaded, and then the first water-soluble low molecular weight compound (B) is mixed. It is important to add a low molecular weight compound (A). 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 A water-soluble low molecular weight compound (B) forms a pseudo-polymer in an inhomogeneous state, so long-term kneading is required to form the pseudo-polymer in a homogeneous state and obtain the desired properties. This is because

 Also, if the first water-soluble low molecular weight compound (A) is added first, bubbles may be generated at the time of kneading and the amount of air in the concrete increases, which may cause a decrease in strength and a decrease in specific gravity. .

 [0022] In this example, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) were each added in an amount of 0.5 to 5.0% by weight based on the amount of water. The first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are mixed in a certain ratio (for example, in the range of 2: 5 to 5: 2). To be mixed into the cement. As described above, the thickening admixture has a thickening effect by forming the pseudo-polymer of the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound (B). In addition to being effective, it does not inhibit hydration unlike the commonly used water-insoluble insoluble admixture based on cellulosic or acrylic water-soluble polymers. It is possible to obtain a concrete composition having excellent holding properties and excellent early strength. According to the results of the experiment, the case where the mixing ratio of the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) was 1: 1 was optimal.

 [0023] Examples of the chemical admixture for concrete include polyether-based water reducing agents such as lignin-based, polycarboxylic acid-based, melamine-based, naphthalene-based, and aminosulfonic acid-based, AE water-reducing agents, and high-performance AE-reducing agents. It can be appropriately selected from commonly used concrete admixtures for concrete such as water reducing agents. Among them, a lipoxyl group-containing polyether-based water reducing agent having excellent compatibility with the thickening admixture is preferably used at a ratio of 0.5 to 5.0% by weight, particularly preferably, with respect to the above-mentioned high strength cement. By blending at a ratio of 1.0 to 5.0% by weight, it is possible to exhibit early strength while maintaining freshness and high fluidity.

[0024] As described above, according to the best mode 1, concrete thread and composite obtained by adding a chemical admixture for concrete and a thickening admixture to cement, water, and aggregate, and kneading the cement admixture are as follows: In addition to using high-strength Portland cement as the cement, and using the cationic surfactant The compound (A) selected from the precipitating agents and the aromatic aromatic compound power The combined power of the selected compound (B) is used as the chemical admixture for concrete and the phase with the thickening admixture. Uses a carboxyl group-containing polyether-based water reducing agent with excellent solubility and is adjusted to a water-cement ratio of 30% to 60%. A concrete composition having excellent properties and self-leveling properties can be obtained.

 [0025] Best mode 2.

 FIG. 1 is a diagram showing an outline of a method for producing a concrete composition used in a shield direct-casting method according to a second preferred embodiment of the present invention. The concrete composition of the present invention comprises cement, water, coarse aggregate, fine aggregate, The first water-soluble low molecular weight compound (A), in which a chemical admixture for concrete is blended with the aggregate and a cationic surfactant is also selected as a thickening admixture, and an aromatic aromatic compound This method uses a thickening admixture containing the second water-soluble low molecular weight compound (B) selected. After kneading the fine admixture with the chemical admixture for concrete and the second water-soluble low-molecular compound (B), the first water-soluble low-molecular compound (A) is added to the kneaded product. And knead again, and finally add coarse aggregate and knead to The door composition to create made. The kneaded mixture is loaded on the truck agitator 3 of the transport vehicle 2, transported to the construction site B while being kneaded, unloaded, loaded into a concrete pump (not shown), and shown in FIG. A concrete casting pipe 38 connected to a pressure jack 35 for placing concrete is pumped to construct a covering concrete 36.

 [0026] Examples of the cement include, but are not particularly limited to, Portland cement such as limestone 'clay' iron oxide and the like, such as ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, and white Portland cement. The ability to use mixed cements such as blast furnace cement, fly ash cement, silica cement, etc. In particular, it is preferable to use early-strength portland cement.

At this time, the water-cement ratio (WZC) is preferably 30 to 60%, more preferably 30 to 40%, and particularly preferably about 35%, as in the best mode 1. Better. In addition, in order to improve fluidity, resistance to material separation, and pumping performance, the fine aggregate ratio (SZa ) Is preferably set to (S / a) = 30 to 45%. If the fine aggregate ratio is less than 30% or more than 45%, the viscosity of the cement paste will decrease and the water resistance will decrease.

 When coarse aggregate with large diameter is used as the coarse aggregate, the unit water volume for obtaining the required slump is small, and it is economical. Need to be considered. In addition, if the maximum size is too large, there are problems such as difficulty in handling concrete, easy separation of materials, and deterioration of pumpability.Therefore, the maximum size of coarse aggregate should not be too large. It needs to be considered. For example, under conditions such as pumping with 3 inch piping, the water cement ratio should be 40% or less, the maximum size of coarse aggregate should be about 13 mm, and the ratio of fine aggregate (SZa) should be set lower than before. Accordingly, it is possible to produce a concrete having high strength while securing high fluidity, pumping property and resistance to material separation.

 The fine aggregate is an aggregate that passes through all the 10 mm screen sieves and passes 85% by weight or more of the 5 mm screen sieve, and the coarse aggregate is an aggregate that does not pass 85% by weight or more through the 5 mm screen sieve. In general, they can be obtained from river sand, sea sand, mountain sand, crushed stone, and the like.

 As the above-mentioned chemical admixture for concrete, as in the best mode 1, polyether-based water reducing agents such as lignin-based, polycarboxylic acid-based, melamine-based, naphthalene-based, or aminosulfonic acid-based, and AE water-reducing agents , A high-performance AE water reducing agent and other commonly used chemical admixtures for concrete. Among them, carboxyl group-containing polyethers with excellent compatibility with the above thickening admixtures The water-reducing agent is preferably added to the above-mentioned cement at a rate of 0.5 to 5.0% by weight, particularly preferably at a rate of 1.0 to 5.0% by weight. Sex can be reliably expressed.

 In this example, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) were each added in an amount of 0.5 to 5.0% by weight based on 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 into the cement at a certain ratio.

In addition, underwater inseparable materials (admixtures) used in conventional underwater inseparable concrete Is caused by the admixture of the thickening admixture with the cement particles, causing a delay in curing.However, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) have a certain ratio. (For example, in the range of 2: 5 to 5: 2) into the cement, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are mixed. Since it forms a pseudopolymer by electrically arranging and exhibits a thickening function, it does not affect the cement particles, so that the above-described hardening delay does not occur.

 Therefore, it is possible to obtain a concrete composition having excellent early strength and excellent water resistance, which is optimally used as concrete of the shield direct-casting method. According to the results of the experiment, the optimal mixing ratio of the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) was 1: 1.

In the kneading, first, a carboxyl group-containing polyether-based water reducing agent, which is a chemical admixture for concrete, in cement, water, and fine aggregate, and a second water-soluble low-molecular compound (B). Sodium alkylaryl sulfonate is added and kneaded to produce a kneaded product. Thereafter, the first water-soluble low molecular weight compound (A), alkylammonium salt, is added to the kneaded product. And then kneading again, and finally adding coarse aggregate and kneading to produce a concrete composition.

 The concrete composition thus obtained is excellent in early strength and fluidity, and also excellent in water resistance as well as easy to work underground or underwater. Since sufficient strength and water resistance can be ensured, it has sufficient properties as a directly-cast concrete lining material for the shield method in the spring formation. In addition, because of its excellent pumping performance and resistance to material separation, it is possible to pump by 3-inch pipes in the pit.

[0029] In the best mode 2, the above-described concrete composition is used as a direct concrete lining material in a shield method. The force described above is not limited to this. Conventionally, a high fluidity concrete is used. The present invention is also applicable to the construction of buildings that are difficult to compact with a vibrator and the construction of concrete where water is present, such as offshore structures and underground structures, where underwater inseparable concrete has been used. The concrete composition is fully applicable. [0030] In the above example, cement, water, fine aggregate, a chemical admixture for concrete, and a second water-soluble low-molecular compound such as sodium alkylaryl sulfonate ( B), knead the mixture, further add the first water-soluble low-molecular compound (A) to the kneaded material, knead the mixture again, and finally add the coarse aggregate and knead the mixture. Force transported to construction site B As shown in Fig. 2 (a), cement, water, fine aggregate, coarse aggregate, the chemical admixture for concrete, and the second After kneading the water-soluble low-molecular compound (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. Add the first water-soluble low molecular weight compound (A) and add Yo, be prepared concrete composition high speed stirred to at Kkuajiteta 3.

 Alternatively, as shown in Fig. 2 (b), cement, water, fine aggregate, coarse aggregate, and a chemical admixture for concrete are kneaded and mixed in a mixer 1 of a concrete plant A, and the kneaded material is mixed with a vehicle 2 for transportation. After being loaded into the truck agitator 3 and transported to the construction site B while stirring at a low speed, the second water-soluble low molecular compound (B) is added at the construction site B, and the mixture is stirred at a high speed with the truck agitator 3 and then The first water-soluble low molecular weight compound (A) may be added to the kneaded material, and the mixture may be further stirred at a high speed to produce the concrete composition.

 By the way, in the concrete composition, as described above, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) have a certain ratio (2 : 5 to 5: When mixed into the concrete in 2), the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) are electrically arranged and simulated. It forms a polymer and improves the early strength and water resistance of the concrete composition. In particular, when the mixing ratio is approximately 1: 1, the bonding strength is the strongest and the viscosity is also large, so that the early strength and the water resistance are greatly improved. On the other hand, if the above mixing ratio deviates from 1: 1, the bonding strength becomes weak and the viscosity becomes small. On the other hand, when the mixing ratio is the same, the viscosity increases as the amount of addition of the compound (A) and the compound (B) increases.

Similar to the conventional concrete composition, the above-mentioned early-strength water-resistant concrete composition also has a reduced viscosity at the casting site where the environmental temperature is low. If oil is mixed into the above concrete composition during pumping to the site, The first water-soluble low-molecular compound (A) is adsorbed on the oil, and as a result, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) The mixing ratio is incorrect! / The viscosity may decrease.

 That is, in the concrete composition, the decrease in viscosity occurs even when the mixing ratio of the compound (A) and the compound (B) is changed. However, when a different thickener is added, the properties of the concrete composition are affected, and the desired properties may not be obtained. Further, when the viscosity of the concrete composition is increased, if water is easily added, the ratio of the compound (A) and the compound (B) to the unit water amount changes, and the characteristics of the concrete composition are changed. There is a risk of deterioration.

 [0032] While pressing, the viscosity of the early-strength water-resistant concrete composition varies depending on the blending ratio of the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B). Therefore, when adjusting the viscosity of the concrete composition, if the compound (A) or the compound (B) is added to the concrete composition and the mixing ratio is adjusted, the concrete composition can be adjusted. Viscosity adjustment can be performed easily without deteriorating the characteristics of the device.

 Next, a specific method of adjusting the viscosity of the concrete composition will be described with reference to the flowchart of FIG.

 First, in a concrete plant, a concrete composition was prepared by kneading the above-mentioned early-strength Portland cement, water, coarse aggregate, fine aggregate, a chemical admixture for concrete, and the thickening admixture. , And measure its viscosity (initial viscosity r? (0)) (Step Sl).

 Next, the viscosity (viscosity r?) Of the concrete composition transported to the casting site was measured (Step S2), and the measured viscosity 7? And the initial viscosity 7? (0) Then, it is determined whether or not the measured viscosity r? Is lower than the initial viscosity r? (0) (step S3).

If the viscosity r? Is lower than the initial viscosity r? (0) (Yes in step S3), a small amount of the first water-soluble low-molecular compound (A) is added to the above concrete composition. And knead again (step S4). Then, it is checked whether the force has recovered the viscosity (step S5). If it has recovered, the concrete composition is poured as it is. If the viscosity does not recover even when the first water-soluble low molecular compound (A) is added, the first water-soluble low molecular compound (A) and the second water-soluble low molecular compound It is estimated that the compounding ratio with the molecular compound (B) is the compounding ratio force that achieves the maximum viscosity of the above-mentioned concrete composition at the in-situ temperature. For this purpose, a small amount of the second water-soluble low-molecular compound (B) is added and kneaded again (step S6). When the viscosity is restored, the concrete composition is poured.

[0034] On the other hand, if the viscosity 7? Is higher than the initial viscosity 7? (0) (No in step S3 and Yes in step S7), the process proceeds to step S8. After adding a small amount of the water-soluble low molecular weight compound (B) and kneading again to lower the viscosity to the initial level, the above concrete composition is poured. In this case, the viscosity can be reduced by adding the first water-soluble low molecular weight compound (A), but the compound (A) may cause a slight generation of bubbles during kneading. Therefore, addition of the above compound (B) is more advantageous in terms of work because kneading is troublesome.

 When the measured viscosity r? Is not so different from the initial viscosity r? (0), the concrete composition may be poured as it is.

[0035] Further, when the concrete composition is pumped by a concrete pump and poured as in the case of constructing a cover concrete in a shield method, the first concrete is pumped by the oil content of the concrete pump. Since it is assumed that the water-soluble low-molecular compound (A) is adsorbed, the above-mentioned first water-soluble low-molecular compound (A) is added to the concrete composition in advance, and then the concrete composition is pumped. If this is the case, the properties of the concrete composition during casting can be reliably maintained at the initial properties.

 Note that the above viscosity adjustment method is not limited to the direct-strength concrete lining material used in the shield method and the early-strength water-resistant concrete used in the construction method. It can also be applied to concrete compositions used for concrete construction in places where water exists, such as objects and underground structures. Example

[0036] As shown in Tables 1 and 2 below, a cement with a high strength of 190 kg / m ³ in water (density; 3.14 g / cm ³ ) 543kg / m ³ and the mixture was adjusted so that the water cement ratio is 35%, which in the concrete chemical admixture, high-performance special admixtures (manufactured by Kao Corporation, carboxyl group-containing polyether-based water reducing agent, (Trade name “Mighty 4000FA”) and an additive mainly composed of sodium alkylaryl sulfonate (trade name “Pisco Top 100FA” manufactured by Kao Corporation). Aggregate (density; 2.63 g / cm ³ ) 597 kg / m ³ is kneaded and kneaded, and the kneaded product is an additive containing an alkylammonium salt as a main component (trade name “Kao Corporation” Pisco Top 100FB ”) was added and kneaded again. Finally, 597 kg / m ³ of coarse aggregate (density: 2.56 g / cm ³ ) was added and kneaded to prepare a concrete composition. At this time, a coarse aggregate having a size of 13 mm or less was used as the coarse aggregate.

[table 1]

[Table 2]

 Water cement ratio (W / C) = 35%

 Fine aggregate ratio (S / a) = 38¾

 Then, material tests as shown in the following (1) to (8) were performed on the above concrete thread.

 (1) Initial properties; Slump flow test (5 minutes, 10 minutes), air volume test, concrete temperature

(2) Retention of aging of fresh concrete: The initial property test items are kneaded at 0, 60, 120, 180 and 240 minutes. (3) Inseparable in water; pH is measured by dropping fresh concrete into water

 (4) Watertightness: A fresh concrete cylindrical specimen was prepared, water pressure was applied to the specimen, the amount of permeated water was measured, and a strength test was conducted.

 (5) Viscosity test: Concrete is poured on a 23-degree slope and the speed is measured.

 (6) Compressive strength test; conducted in accordance with JIS A 1108

 (7) Pumping test: Confirming pumpability with 3 inch piping (measurement of pressure loss in pipe, confirmation of concrete pressure loss)

 (8) Measurement of shrinkage; Measure shrinkage by length change test

 Tables 3 and 4 show the measurement results of the compressive strength and fresh properties of the above test results, and Table 5 shows the properties of each concrete composition of the present invention with those of the conventional high fluidity concrete and underwater concrete. The result of the comparison is shown. The high fluid concrete used as a comparative example was prepared based on the "High fluid concrete construction guidelines" and the underwater concrete was prepared based on the "underwater non-separable concrete design and construction guidelines (draft)".

[Table 3]

[Table 4]

[Table 5] Concrete of the present invention High flowable concrete Underwater concrete High flowability 〇 よ う As is clear from Tables 3 to 5, the concrete composition of the present invention is excellent not only in fluidity, material separation resistance, and early strength, but also in water resistance, and furthermore, It was confirmed that the pumping properties and self-leveling properties were also excellent.

[0037] Best mode 3

 In the above-mentioned best mode 2, the force described for the direct-strength concrete lining material of the shield method and the early-strength water-resistant concrete to be used.The concrete composition of the present invention has a water-resistant property as shown in the above examples. In addition, since it is excellent in self-leveling property, it can be suitably used for construction of cast-in-place concrete piles.

 For cast-in-place concrete piles, excavate the ground with a machine, fill the excavation pit with a stabilizing solution to stabilize the excavation hole wall, and then insert concrete by inserting a reinforcing bar into the excavation hole. This is a general term for the method of constructing piles on site, and typical methods include the earth drill method, reverse method, and all casing method. Fig. 4 is a construction procedure diagram of the earth drilling method. In this method, as shown in Figs. 4 (a) and (b), the ground is first ground using a ground drill 21 while pouring a stable liquid 22 such as bentonite liquid. Drill 20 to form borehole 23. Then, as shown in FIGS. 4 (c) to 4 (e), after inserting the reinforcing cage 24 into the inside of the excavation hole 23, the concrete composition is introduced into the above-mentioned excavation hole 23 through the tremee pipe 25 from a concrete pump (not shown). Buildings are reinforced concrete piles (concrete piles) 26. The tremy tube 25 is removed after the concrete pile 26 is constructed.

[0038] By the way, when the above concrete is poured, if the self-leveling property of the concrete composition to be poured is low, the concrete may involve muddy water, earth and sand on the perforated wall. It is conceivable that the quality of the resin is reduced. Therefore, it is necessary to add extra height to the specified concrete top height in consideration of safety. Above must The required depth of the extra embankment 26k generally depends on the method of construction, but it is required to be about 80cm for the earth drill method or reverse method that stabilizes the borehole wall with muddy water, and about 50cm for the all casing method. After the concrete is cast, a pile head treatment is required to cut through the extra 26k where the layance (mud layer) and muddy sediment are mixed.

[0039] In addition, when cast in place with gravel or gravel layers, concrete may be washed away by underground water or pressurized groundwater, and concrete used in such places may be cement, water, aggregate, or the like. For example, it is possible to use underwater concrete with excellent water resistance and low occurrence of breathing, which is mixed with concrete admixtures such as inorganic admixtures such as silica gel and bentonite and AE water reducing agents. Even when concrete is used, there is a problem with self-leveling properties, so it was necessary to increase the capacity as with ordinary concrete.

 Therefore, when constructing a cast-in-place concrete pile as described above, the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (A) similar to the above-described best modes 1 and 2 ( When a concrete composition containing a thickening admixture containing B) is used, both the water resistance and self-leveling property of the concrete composition can be improved, and there are underground water and pressurized groundwater. It is thought that a reliable concrete pile can be constructed even in this case. Also, at this time, first, concrete with the above-mentioned thickening admixture is poured into the concrete to a predetermined depth, and then concrete without the above-mentioned thickening admixture is poured to construct a concrete pile. If so, the amount of expensive concrete containing the above thickening admixture can be reduced, and material costs can be significantly reduced.

[0040] Figs. 5 (a) to 5 (c) are diagrams showing a method of constructing a cast-in-place concrete pile according to the third best mode of the present invention. In this example, the ground 20 is drilled using a drilling machine such as an earth drill. After excavating the excavation hole and stabilizing the excavation hole wall, a reinforcing bar 24 is inserted into the excavation hole 23 and concrete is poured. At this time, first, concrete with high self-leveling property and excellent water resistance (hereinafter referred to as high self-leveling water-resistant concrete) 11 is poured into a predetermined depth, and then water and ordinary Portland cement are added. Concrete piles 12 are kneaded with concrete and aggregates to construct concrete piles 10. [0041] The high self-leveling water-resistant concrete is selected from cement, water, coarse aggregate, and fine aggregate, in which, in addition to a chemical admixture for concrete, a cationic surfactant is also selected as a thickening admixture. It contains a water-soluble low-molecular compound (A) and a second water-soluble low-molecular compound (B) selected from anionic aromatic compounds (B). First, a kneaded material is prepared by kneading a chemical admixture for concrete and the second water-soluble low-molecular compound (B) into cement, water, and fine aggregate, and then adding the kneaded material to the kneaded material. The first water-soluble low-molecular-weight compound (A) is added and kneaded again, and finally the coarse aggregate is mixed and kneaded to produce the concrete composition.

 The above-mentioned chemical admixture for concrete can be appropriately selected from commonly used chemical admixtures for concrete. Among them, a carboxyl group-containing admixture excellent in compatibility with the above-mentioned thickening admixture is particularly preferred. By blending the polyether-based water reducing agent in a proportion of 0.5 to 5.0% by weight, particularly preferably 1.0 to 5.0% by weight with respect to the cement, fluidity and self-leveling can be obtained. Performance can be improved.

 [0042] Examples of the cement include, but are not particularly limited to, Portland cements such as limestone 'clay' iron oxide and other raw materials such as ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, and white Portland cement. And the ability to use mixed cement such as blast furnace cement, fly ash cement, silica cement, etc. In particular, it is preferable to use early-strength Portland cement.

 In the high self-leveling waterproofing concrete of this example, the water-cement ratio (WZC) is preferably 30 to 60%, more preferably 30 to 40%, and particularly preferably about 35%. preferable.

 The kneading method is the same as in the first and second embodiments, and the description is omitted.

As shown in FIG. 5 (a), the high self-leveling waterproof concrete has high self-leveling properties because the high self-leveling waterproof concrete 11 has high self-leveling properties, as shown in FIG. 5 (a). However, the concrete surface after casting is flatter than that of ordinary concrete. Therefore, entrapment of muddy water, pore wall sediment, etc. at the time of pouring concrete can be significantly reduced. In addition, since the high self-leveling waterproof concrete has excellent water resistance, it is possible to prevent a decrease in strength due to substantial addition of water due to muddy water even in the ground where underground water or pressurized groundwater is present, and to prevent the use of muddy water. This can prevent the quality from being deteriorated due to the outflow of cement particles.

 In addition, the high self-leveling water-resistant concrete has excellent pumpability and fluidity, and material separation resistance, so that material separation during pumping and filling can be effectively reduced only. The occurrence of breathing can also be reduced.

 Further, in this example, as shown in FIG. 5 (b), after the high self-leveling waterproofing concrete 11 is cast to a predetermined depth, the ordinary concrete 12 is cast and the concrete pile 10 is constructed. By doing so, the amount of expensive high self-leveling waterproofing concrete containing the thickening admixture is reduced, and the material cost is reduced.

 That is, while the lower end of the tremy tube 25 is kept in the cast high self-leveling waterproof concrete 11, the ordinary concrete 12 is pressure-fed from the tremy tube 25 while gradually pulling up the tremy tube 25. As a result, since the high self-leveling waterproof concrete 11 having excellent water resistance and self-leveling property always exists on the surface of the poured concrete, the concrete surface remains flat. No muddy water or sediment on the wall. Therefore, since the amount of the extra pile 10k of the concrete pile 10 can be extremely reduced, the pile head treatment can be simplified.

[0045] Best mode 4.

 In the above best modes 1 to 3, aggregates obtained by force such as river sand, sea sand, mountain sand, and crushed stone (ordinary aggregates) were used as the aggregates. In the case where a material is blended, the additive containing the first water-soluble low-molecular compound (A) and the second water-soluble low-molecular compound (B) is blended as a thickening admixture, The different specific gravity aggregate can be uniformly dispersed in the concrete.

Normally, it is blended with lightweight concrete such as structural lightweight concrete to reduce the weight of building slabs, floors, and roof slabs, and non-structural concrete mainly for heat insulation, covering, or sound absorption. As an aggregate, for example, as disclosed in JP-A-2001-261413 and JP-A-8-26853, a volcano having a smaller specific gravity than ordinary aggregate is used. Artificial lightweight aggregates such as gravel and other natural lightweight aggregates such as mesalite and asanolite (these are also trade names) are used.

 In addition, concrete structures that require a large weight per unit volume, such as hydraulic structures such as embankments and substructures, and radiation treatment such as accelerator facilities, uranium treatment facilities, and nuclear reactor facilities As disclosed in Japanese Patent Application Laid-Open No. 2-172846 and Japanese Utility Model Application Laid-Open No. 6-76899, for example, a shield wall provided in a facility may be made by crushing natural rock such as magnetite, or by shot blasting. Heavy concrete containing heavy aggregates with higher specific gravity than ordinary aggregates, such as steel fine granules for use or granules obtained by forging or hot pressing of waste iron materials .

 By the way, in the case of lightweight concrete containing the aggregate with a smaller specific gravity than that of ordinary aggregate, and heavy concrete containing the aggregate with a higher specific gravity as described above, the material separation is smaller than that in the case where the ordinary aggregate is combined. There is a problem that distribution of the above-mentioned aggregate becomes uneven because of easy occurrence. In other words, if the distribution of aggregate becomes uneven, the strength of concrete decreases in the case of lightweight concrete. Particularly, when the lightweight concrete is placed in a dry state, the shrinkage of the concrete becomes large due to an increase in drying shrinkage, so that the bending strength and the durability tend to be remarkably reduced.

 On the other hand, in hydraulic structures such as embankments and substructures, when the distribution of aggregates is not uniform, the heat generation increases and the drying shrinkage increases, resulting in cracks and the like. There was a problem with sex. In the case of a shielding wall, there is a problem that the shielding effect is reduced because the radiation shielding effect varies. Therefore, when manufacturing the above lightweight concrete, in addition to a water reducing agent such as an AE water reducing agent, a material separation reducing agent (viscosity admixture) mainly composed of a cellulose or acrylic water-soluble polymer is blended. Attempts have been made to suppress the material separation while suppressing the decrease in fluidity, but it has been difficult to sufficiently suppress the material separation.

In addition, for the above heavy concrete, at present, stratification is performed as necessary to eliminate uneven distribution of aggregates. The strength, strength and radiation shielding effect were not enough. In addition, the particle size distribution of the aggregate is adjusted, and irregularities are provided on the surface to improve the adhesion to cement. There have been proposals for such methods, but they have not been sufficiently effective yet.

 [0047] The concrete composition containing an aggregate of different specific gravity according to the best mode 4 mixes cement and water with an aggregate that also has an artificial lightweight aggregate power, and a chemical admixture for concrete (water reducing agent) and a thickening agent. In this example, a first water-soluble low-molecular-weight compound (A) selected from cationic surfactants, and an aromatic aromatic compound are used as the above-mentioned thickening admixture. Compound An additive containing a second water-soluble low molecular weight compound (B) selected from the group was used. In addition, the production method is as follows. First, a kneaded material is prepared by kneading a cement admixture for cement, water, and fine aggregate with the chemical admixture for concrete and the second water-soluble low-molecular compound (B). Then, the first water-soluble low-molecular compound (A) is added to the kneaded material and kneaded again, and finally, coarse aggregate is added and kneaded to produce a concrete composition. This makes it possible to uniformly disperse the artificial lightweight aggregate in concrete while ensuring sufficient fluidity.

 As the artificial lightweight fine aggregate, for example, a raw material such as expansive shale, expansive viscosity, or fly ash is prepared into a fine powder and then granulated and calcined, or a calcareous or siliceous material. Foamed or fired, or pearlite, obsidian, etc. fired and expanded (pearlite), etc., which can be used as a structural material for RC structures, or for heat insulation or fireproof coating. The type, particle size, fine aggregate ratio, and compounding amount are appropriately determined depending on the application such as the gas used for the non-structural material.

 The chemical composition of these artificial lightweight aggregates is mainly silica (SiO

 2), Alumina (Al O

 23) Metals such as iron oxide (FeO, FeO), calcium oxide (CaO), and magnesium oxide (MgO)

 twenty three

 For oxides, the absolute dry gravity is, for example, less than 2.3 for fine aggregate and less than 2.0 for coarse aggregate in the case of structural lightweight concrete aggregate (according to JIS A 5002).

[0049] Examples of the chemical admixture for concrete added to increase the fluidity of the concrete composition include lignin-based, polycarboxylic acid-based, melamine-based, naphthalene-based, and aminosulfonic acid-based polyadmixtures. It can be appropriately selected from commonly used concrete admixtures for concrete, such as an ether type water reducing agent, a carboxyl group-containing polyether type water reducing agent, an AE water reducing agent, and a high performance AE water reducing agent.

Thus, cement and water, fine aggregates made of artificial lightweight aggregates, a chemical admixture for concrete, and a second water-soluble low molecular weight compound (B) selected from anionic aromatic compounds After kneading to produce a kneaded product, the first water-soluble low molecular weight compound (A) selected by the cationic surfactant force is added to the kneaded product, and the mixture is kneaded again. The concrete aggregate is mixed and kneaded to produce a concrete composition.Therefore, sufficient fluidity is ensured even when an artificial lightweight aggregate having a specific gravity lighter than ordinary aggregate is used as the aggregate. The artificial lightweight aggregate can be uniformly distributed in the concrete while maintaining the same. Therefore, workability can be improved and lightweight concrete with uniform strength can be produced.

 [0050] In the best mode 4, the force using artificial lightweight aggregate as the lightweight aggregate is not limited to the present invention. The present invention is not limited to natural lightweight aggregate such as volcanic debris and by-products such as coal shell. It is needless to say that the present invention can be applied to a case where a lightweight aggregate is used, or a case where a lightweight aggregate obtained by combining the above-mentioned natural lightweight aggregate or by-product lightweight aggregate with an artificial lightweight aggregate is used!

 [0051] Best mode 5

 In the above-mentioned best mode 4, a concrete composition containing a lightweight aggregate is used for a hydraulic structure such as a 1S embankment or a substructure of a building, which has a specific gravity of 4.0 or more. Even when producing heavy concrete using part or all of the same, in addition to water, cement, aggregate, a first water-soluble low-molecular compound (A) selected from cationic surfactants, When the admixture containing the second water-soluble low molecular weight compound (B) selected from an anionic aromatic compound is blended as a thickening admixture, the above-mentioned heavy aggregate can be uniformly distributed in the concrete. Can be. As the heavy aggregate, for example, iron ore such as magnetite or sand iron, metal such as iron, or pearlite can be used. Further, these heavy aggregates may be blended together with ordinary aggregates as fine aggregates or coarse aggregates, or may be used for both fine aggregates and coarse aggregates.

As a result, the inhomogeneity due to the aggregate in the vertical direction in heavy concrete is improved, the rich mixture (mixture with a large amount of mortar) is not formed in the upper part of the concrete, the generation of cracks due to drying shrinkage is suppressed, and the durability is reduced. Can be suppressed. In addition, hydraulic structures and substructures can be constructed without straddling, improving work efficiency and durability without structural weaknesses such as piles. It is possible to fabricate structures with high V. [0052] The present invention is not limited to heavy concrete used for hydraulic structures and substructures of buildings, and is also applicable to shielding concrete for shielding radiation. That is, when producing the above shielding concrete, a first water-soluble low-molecular compound (A) selected from cationic surfactants and a second water-soluble low-molecular compound selected from anionic aromatic compounds are used. If the admixture containing the compound (B) is blended as a thickening admixture, the heavy aggregate can be uniformly distributed in the concrete without performing stratification or the like. Therefore, since there is no structural weak portion due to stratification, the durability of the shielding concrete can be improved, and since the heavy aggregate is homogeneously distributed in the concrete, the dispersion of the radiation shielding effect is eliminated. And the shielding effect can be improved.

 Further, in the above-described best modes 4 and 5, a case where a lightweight aggregate or a heavy aggregate is mixed with a part or the whole of the aggregate has been described. However, the present invention relates to, for example, construction waste materials ゃ copper slag aggregate and the like. As in the case of using aggregates made of waste materials, the present invention can also be applied to the case of using aggregates in which both lightweight aggregates and heavy aggregates are mixed.

 Industrial applicability

[0053] As described above, according to the present invention, it is possible to obtain a concrete composition which is excellent in early strength, fluidity, self-leveling property, resistance to material separation and water resistance. It is possible to construct concrete covering by the shield method in the spring water stratum, to construct buildings that are difficult to compact by vibrators, and to construct concrete in places where water exists, such as marine structures and underground structures. Construction can be performed easily and reliably.

 Also, when constructing a concrete pile, it is possible to significantly reduce entrapment of muddy water, pores, soil, etc. at the time of concrete pouring, so it is possible to construct a concrete pile with almost no extra filling .

 Furthermore, even when an aggregate having a large specific gravity difference from that of ordinary aggregate is blended, the above aggregate can be uniformly dispersed in the concrete. Can be easily produced.

Claims

The scope of the claims [1] A concrete composition obtained by adding a thickening admixture to cement, water, and aggregate and kneading the mixture, wherein the first water-soluble low-molecular compound (A) and the second water-soluble compound are used as the thickening admixture. An additive containing an amphoteric low-molecular compound (B), wherein the compound (A) and the compound (B) are combined with a compound (A) selected from amphoteric surfactants and an aionic surfactant. A combination of a compound (B) selected from the group consisting of a compound (A) and a compound selected from the group consisting of a compound (A) and an ionic aromatic compound, and a combination of a compound (B) selected from the group consisting of a cationic surfactant and a cationic surfactant the combination of compounds selected with (a) a compound selected from the bromine compound and (B) from, characterized by using any of the additives of the additive force selected concrete one Bok composition _Q  [2] As the thickening admixture, an admixture containing a compound (A) selected from cationic surfactants and a compound (B) selected from aionic aromatic compounds is used, and the compound ( 2. The concrete composition according to claim 1, wherein the compound (A) and the compound (B) are mixed at a ratio of 0.5 to 5.0% by weight with respect to a unit water amount.  [3] The concrete composition according to claim 1 or claim 2, wherein the water cement ratio in the concrete composition is 30 to 60%.  [4] The concrete composition described above, wherein a chemical admixture for concrete is further blended in a ratio of 0.5 to 5.0% by weight with respect to the cement. 3. The concrete composition according to any one of 3.  [5] The concrete composition according to claim 4, wherein a carboxyl group-containing polyether-based water reducing agent is used as the chemical admixture for concrete.  [6] The method according to claim 1, wherein the coarse aggregate and the fine aggregate are used as the aggregate, and the fine aggregate ratio, which is the ratio of the fine aggregate contained in the aggregate, is 30 to 45%. The concrete composition according to any one of claims 1 to 5.  [7] At least a part or all of the aggregate is characterized by using one or both of an aggregate having a lower specific gravity than ordinary aggregate and an aggregate having a higher specific gravity than ordinary aggregate. The concrete composition according to any one of claims 1 to 5. [8] A method for producing the concrete composition according to any one of claims 1 to 7 After the second water-soluble low-molecular compound (B) is added to cement, water and aggregate and kneaded, the first water-soluble low-molecular compound (A) is added to the kneaded material. A method for producing a concrete composition, comprising adding and kneading the mixture again to produce the concrete composition.  [9] A method for adjusting the viscosity of the concrete composition according to any one of claims 1 to 7, wherein the concrete composition further comprises the first water-soluble low-molecular compound ( A concrete composition characterized in that the viscosity of the concrete composition is adjusted by adding one or both of A) and the second water-soluble low molecular weight compound (B). Viscosity adjustment method.  [10] The method for adjusting the viscosity of a concrete composition according to claim 9, wherein the initial compounding ratio of the compound (A) and the compound (B) is approximately 1: 1.  [11] When the viscosity of the concrete composition is lower than the viscosity at the time of production, the first water-soluble low-molecular compound (A) is added to the concrete composition. 11. The method for adjusting the viscosity of a concrete composition according to claim 9 or claim 10.  [12] When the viscosity of the concrete composition at the casting site is higher than the viscosity at the time of production, the second water-soluble low-molecular compound (B) is added to the concrete composition. 11. The method for adjusting the viscosity of a concrete composition according to claim 9 or claim 10, characterized in that:  [13] When the concrete composition is pumped by a concrete pump and poured, the first water-soluble low-molecular compound (A) is added to the concrete composition in advance and then pumped. The method for adjusting the viscosity of a concrete composition according to any one of claims 9 to 12, characterized in that: [14] A method of constructing a cast-in-place concrete pile, in which a reinforcing steel cage is inserted into a hole excavated from the ground, a concrete composition is pumped into the hole by passing a concrete composition through a tremy pipe, and a concrete pile is constructed, A method for constructing a cast-in-place concrete pile, wherein the concrete composition according to any one of claims 1 to 6 is used as the concrete composition. First, concrete containing the thickening admixture is poured into the concrete to a predetermined depth, and then concrete not containing the thickening admixture is poured to construct a concrete pile. 15. The method for constructing a cast-in-place concrete pile according to claim 14.