JPH1135934A - Self hardening composition for mud adding type soil pressure shield method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition most suitable for a self-hardening additive with high strength after hardening without detriment to the initial flowability by incorporating a thickening component or a thickening component together with an admixture into a hydraulic component as a main component. SOLUTION: This composition comprises preferably 50-90 wt.% of a hydraulic component (A), 10-50 wt.% of a thickening component (B), 0-20 wt.% of an admixture (C). The component (A) is cement or a mixture of cement with slag or fly ash, and the component (B) is bentonite or clay and the component (C) comprises a viscous adjuvant, fluidizing agent or a retarder. As the viscous adjuvant is employed a viscous organic compound such as carboxymethyl cellulose, polyvinyl alcohol, etc., and as the fluidizing agent is employed a high mol.wt. compound for cement or concrete. The amounts of tricalcium aluminate and tetracalcium aluminoferrite contained in the component (A) are 2-7wt.% and 2-13 wt.%, respectively, and add up to 5-16 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-hardening composition for controlling the plastic fluidization state of excavated earth and sand and for the purpose of earth pressure control in a mud-type earth pressure shield method. is there. 2. Description of the Related Art In recent years, the use of a mud-type earth pressure shield method has been rapidly increasing in sewage, subway, electric power, gas communication and other beam construction work from the viewpoint of economic efficiency and pollution control. This method is a method of keeping the face in muddy water, and excavating while suppressing the earth pressure and water pressure of the ground acting on the face with that pressure, and it is extremely important to control the state of excavated soil well . The invention relates to a self-hardening composition used for this purpose.

[0002]

2. Description of the Related Art In a muddy type earth pressure shield method, it is necessary to maintain the plastic fluidized state of earth and sand excavated by a cutter and the earth pressure of a face well, and by controlling these, stable excavation is performed. Becomes possible. The properties of the excavated earth and sand are various, and the excavation can be stabilized by adding additives corresponding to these properties. The properties required of such additives include (a) high density and high viscosity, (b) low separability of the additives themselves, and (c) including materials that cause clogging. And the like.

[0003] Conventionally, such additives are mainly composed of clay and bentonite, and basically have no hardening action. However, in recent years, excavated soil and mud containing this additive (hereinafter referred to as excavated mud) remains between the ground in the tunnel and the segment consisting of concrete blocks (tail void portion), and the backfill material to be injected later is used. There is a problem that it prevents hardening and results in subsidence of the ground. In particular, the tail void becomes large in the curved portion of the tunnel, and the above problem becomes important. For this reason, it is desired that the excavated mud is finally provided with curability. By the way, in the shield method, an example of adding cement, which is a self-hardening material, has been conventionally known, but until now, a small amount is added for the purpose of stopping water or the like, or is added for the purpose of stabilizing the earth removal. The excavated mud itself was not used in such a way that it actively developed strength.

[0004]

In general, it is possible to harden muddy water and mud by adding a hydraulic material such as cement or slag. However, in the mud-type earth pressure shield method, the excavated mud must maintain a good plastic fluidized state for a while after excavation. It is required that it does not set for at least 24 hours, and in some cases about 3 days. However, thereafter, it is desired that the strength equivalent to that of the backfill material is immediately developed. Here, when ordinary cement or the like is used as it is,
In order for the excavated mud to which this is added to finally develop sufficient strength, it is necessary to add a relatively large amount of cement, etc., but when a large amount of cement, etc. is added, the initial plastic fluidization state is reversed. There is a problem that greatly damages. Further, in order for the excavated mud to maintain a good plastic fluidized state, an appropriate viscosity is necessary, but even if ordinary cement or the like is used as it is, the required viscosity cannot be obtained.

[0005] As described above, the additive used in the mud pressure shield method is required to have appropriate properties with respect to the timing of the onset of the hardening property and the hardening strength. However, such additives are conventionally known. Not. The present invention solves such a conventional problem as to the additive used for the mud pressure shield method, and uses a hydraulic component mainly composed of cement having a high content of belite, and uses a bentonite By mixing an admixture consisting of a thickening component such as clay, and other organic components, a self-hardening composition that does not impair initial fluidity and has high strength after curing is obtained. An object of the present invention is to provide an optimum composition as a self-hardening additive in a pressure shield method.

[0006]

That is, the present invention provides (1) an additive used in a muddy earth pressure shield method,
The present invention relates to a self-hardening composition comprising a hydraulic component as a main component and comprising a hydraulic component and a thickening component, or containing an admixture together with the hydraulic component and a thickening component. The self-hardening composition of the present invention comprises a hydraulic component (A) as a main component, and a thickening component (B) and, if necessary, an admixture (C). By using the hydraulic component and the thickening component together, the mud can be given an appropriate viscosity, the initial plastic fluidized state can be maintained, and sufficient strength can be developed after a certain period of time. Admixtures enhance fluidity,
Alternatively, it is used for the purpose of adjusting the curing action and the like. This admixture may be added as needed.

The self-hardening composition according to the present invention preferably comprises (2) a hydraulic component (A): 50 to 90% by weight, and a thickening component.
(B): 10 to 50% by weight and admixture (C): 0 to 20% by weight.

The self-hardening composition according to the present invention is, specifically, (3) the hydraulic component (A) is cement or a mixture of cement and slag or fly ash, and the thickening component (B) is The bentonite or clay, admixture (C) comprises a viscosity aid, a superplasticizer or a retarder. As the hydraulic component (A), a component mainly composed of cement is used. Specifically, a simple cement or a mixture of cement with slag or fly ash is used. Hardening is given to the excavated mud by cement.
In addition, by using slag or fly ash together with cement, slag and fly ash have a favorable effect on the hydration reaction of cement, and the strength of the cured product can be increased. In addition, fly ash and the like have an advantage of increasing fluidity. Bentonite, clay, etc., or a mixture thereof can be used as the thickening component (B). The viscosity that cannot be obtained with plain cement can be supplemented by this thickening component. As the admixture (C), a viscosity auxiliary, a fluidizing agent, a retarder and the like are used. Organic compounds having viscosity such as carboxymethylcellulose, methylcellulose and polyvinyl alcohol can be used as the viscosity aid. Further, as the fluidizer, a polymer compound known as a general fluidizer for cement and concrete can be used.

The self-hardening composition of the present invention comprises (4) tricalcium aluminate (3Ca) contained in a hydraulic component cement.
The content of O.Al ₂ O ₃ ) is 2 to 7% by weight, and the content of tetracalcium iron aluminate (4CaO.Al ₂ O ₃ -Fe ₂ O ₃ ) is ₂ to 13% by weight. the amount is 5 to 16 wt%, the remainder of belite (2CaO · SiO ₂₎ content of 30 wt% or more, alite (3CaO · SiO ₂₎ content of those is preferably 50 wt% or less. (5) Belite (2CaO.SiO ₂ ) content is 50% by weight or more, and alite (3CaO.SiO ₂ ) content is 4% by weight.
More preferably, it is 0% by weight or less. Tricalcium aluminate (3CaO.Al ₂ O ₃ : C ₃ A) and iron tetracalcium aluminate (4CaO.Al ₂ O ₃ -Fe ₂ O ₃ : C ₄ AF) in the cement component can cause the initial hydration. It is an interstitial component that accelerates, and by limiting this to the above range, it is possible to suppress initial rapid hardening and maintain good fluidity. Belite (2CaO.SiO ₂ : C ₂ S) as a cement component is alite (3CaO.Si)
Although hydration is slower than that of O ₂ : C ₃ S), its long-term strength is high, so it is possible to maintain the initial fluidity by increasing the content of belite and to increase the long-term strength after curing. it can.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. The self-hardening composition of the present invention is an additive used in a mud-type earth pressure shield method, and includes a hydraulic component.
(A), a thickening component (B) and an optional admixture (C)
It consists of As the hydraulic component, cement,
A mixture of slag and fly ash is used. Preferably, the cement has a minimal amount of interstitial components that promote initial hydration. By reducing the gap component, a favorable plastic fluidized state can be easily ensured even in a high viscosity region.

Specifically, tricalcium aluminate (C
₃ A) content of 2-7% by weight of the content of iron aluminate tetracalcium (C ₄ AF) is a 2 to 13 wt%, the C ₃
The total amount of A and C ₄ AF is 5 to 16% by weight, the content of belite (C ₂ S) forming the remaining constituent minerals is 30% by weight or more, and the content of alite (C ₃ S) is Those having a content of 50% by weight or less are suitable. More preferably, the belite content is 50% by weight or more and the alite content is 40% by weight or less.

[0012] C ₃ A and C ₄ AF are gaps ingredients that promote the initial hydration in cement hydration, C ₃
A exceeds 7% by weight, or C ₄ AF is 13% by weight
If the total amount exceeds 16% by weight, or if the total amount exceeds 16% by weight, the initial fluidity decreases. However, cement containing less than 2% by weight of each of C ₃ A and C ₄ AF and having a total amount of less than 5% by weight causes problems such as restrictions on raw materials and difficulty in firing in production. The amount is preferably within the above range.

Alite (C ₃ S) is usually the main component of Portland cement, and usually has a higher content of alite than belite (C ₂ S). However, belite has a characteristic that it has a longer hydration rate and a lower strength development property than alite, but has a high long-term strength development property. Therefore, as a component of the cement used in the self-hardening composition of the present invention, one having as high a content of belite as possible is preferable, and one having a belite content of 30% by weight or more and an alite content of 50% by weight or less is suitable. is there. More preferably, the belite content is higher than that of alite, and a belite content of 50% by weight or more and an alite content of 40% by weight or less is preferable.

As described above, the cement used in the present invention is suitably one in which the initial hydration promoting component is suppressed as compared with ordinary Portland cement. When ordinary Portland cement is used, a retarder is added as an admixture. Is preferred.

As the slag which forms a hydraulic component together with cement, blast furnace slag, steelmaking slag and the like are used.
Particularly, granulated slag having a high hardening action is preferable. Slag has latent hydraulic properties and acts as an effective hardening component when blended with cement. In addition, fly ash itself does not have self-hardening properties, but causes a pozzolanic reaction using cement as a stimulant to contribute to hardening.
In particular, it greatly contributes to the promotion of long-term strength. Fly ash is spherical fine particles, and is effective for obtaining a good plastic fluidized state.

The hydraulic component (A) is used in the range of 50 to 90% by weight based on the solid content of the self-hardening composition. When the hydraulic component is less than 50% by weight, the self-hardening property of the excavated mud, which is the object of the present invention, is insufficient. On the other hand, if the content exceeds 90% by weight, the amount of the thickening component is reduced, so that sufficient viscosity cannot be imparted. There is a possibility that the fluidized state cannot be maintained.

The thickening component (B) is used alone or as a mixture of bentonite, clay and the like. This thickening component is used in the range of 10 to 50% by weight based on the solid content of the self-hardening composition. If the amount is less than 10% by weight, the application of viscosity becomes insufficient, and if it exceeds 50% by weight, curing is hindered. Depending on the nature of the excavated mud,
The viscosity of the additive added to the excavated mud is 1000 to 10
It is required to have a viscosity of about 000 cp and a viscosity that can be adjusted by adjusting the blending amount. In the present invention, an appropriate viscosity can be obtained by adjusting the type and the amount of the thickening component.

As the admixture (C), a viscosity auxiliary, a fluidizer, a retarder and the like are used. Among them, as viscosity aids, for example, CMC (carboxymethylcellulose),
MC (methyl cellulose), ΔVA (polyvinyl alcohol) and the like are used. These can give viscosity in a very small amount, and are added for the purpose of assisting the thickening component. In addition, a fluidizing agent is added to enhance fluidity. As the fluidizing agent, a polymer compound such as an admixture for cement / concrete represented by naphthalenesulfonic acid, polycarboxylic acid and a salt thereof is used. In general, fluidity tends to decrease as viscosity increases. However, by adding these polymer compounds, appropriate fluidity can be imparted while having high viscosity. In addition, a retarder such as citric acid can be added as an auxiliary component to significantly slow the setting action of the cement.

[0019]

Examples and Comparative Examples Examples of the present invention are shown below together with comparative examples. In addition, these are illustrations and do not limit the scope of the present invention.

Example 1 250 g of bentonite of 250 mesh as the thickening component (B)
Was added to 1000 cc of water to prepare a viscous liquid. On the other hand, the hydraulic component (A) has a mineral composition of 5% by weight of C ₃ A, 11% by weight of C ₄ AF, 33% by weight of belite, and 45% by weight of alite, 400 g of Portland cement adjusted to a brane specific surface area of 3300 cm ² / g
And 200 g of slag having a Blaine specific surface area of 4000 cm ² / g, and a polycarboxylic acid fluidizer 6.5 as an admixture (C).
g, and these were dispersed in 800 cc of water. This dispersion and the above viscous liquid were mixed to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Example 2 350 g of bentonite of 250 mesh as the thickening component (B)
Was added to 1000 cc of water to prepare a viscous liquid. On the other hand, the hydraulic component (A) has a mineral composition of C ₃ A content of 2% by weight, C ₄ AF content of 8% by weight, belite content of 56% by weight, and alite content of 28% by weight, Brain specific surface area
450 g of Portland cement adjusted to 3300 cm ² / g
And fly ash 15 with a specific surface area of 5000 cm ² / g
0 g and 5.0 g of a polycarboxylic acid fluidizer as an admixture (C), and these were dispersed in 800 cc of water. This dispersion and the above viscous liquid were mixed to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Example 3 A viscous liquid was prepared as a thickening component (B) by adding 1000 cc of water to 300 g of Kibushi clay, while a hydraulic component (A) was prepared as follows:
It has a mineral composition with a C ₃ A content of 9% by weight, a C ₄ AF content of 9% by weight, a belite content of 26% by weight, and an alite content of 50% by weight, and is adjusted to a brane specific surface area of 3150 cm ² / g. Using 300 g of ordinary Portland cement and 300 g of fly ash having a Blaine specific surface area of 5,000 cm ² / g, a naphthalene sulfonic acid fluidizer 12.0 was used as an admixture (C).
g and 3.0 g of citric acid as retarder were dispersed in 800 cc of water. The viscous liquid was mixed with this dispersion to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Example 4 300 g of bentonite of 250 mesh as the thickening component (B)
Was added to 1000 cc of water to prepare a viscous liquid. On the other hand, the hydraulic component (A) has a mineral composition of C ₃ A content of 2% by weight, C ₄ AF content of 8% by weight, belite content of 56% by weight, and alite content of 28% by weight, Brain specific surface area
Using 500 g of Portland cement adjusted to 3300 cm ² / g, 6.0 g of a naphthalenesulfonic acid-based fluidizing agent as an admixture (C), and these were dispersed in 800 cc of water.
This dispersion and the above-mentioned viscous liquid were mixed to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Example 5 150 g of bentonite of 250 mesh as the thickening component (B)
A viscous liquid was prepared by adding 5 g of methylcellulose as an admixture (c) to 1000 cc of water. On the other hand, as the hydraulic component (A), a C ₃ A content of 5% by weight, a C ₄ AF content of 11% by weight,
Belite content 33 wt%, has a mineral composition of alite content 45 wt%, Portland cement 400g adjusted to Blaine specific surface area of 3300 cm ² / g, and a slag 200g of Blaine specific surface area of 4000 cm ² / g used , Admixture (C)
6.0 g of a naphthalenesulfonic acid-based fluidizing agent was used, and these were dispersed in 800 cc of water. This dispersion and the above-mentioned viscous liquid were mixed to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Example 6 200 g of bentonite of 250 mesh as the thickening component (B)
Was added to 1000 cc of water to prepare a viscous liquid. On the other hand, the hydraulic component (A) has a mineral composition of C ₃ A content of 2% by weight, C ₄ AF content of 8% by weight, belite content of 56% by weight, and alite content of 28% by weight, Brain specific surface area
Using 500 g of Portland cement adjusted to 3300 cm ² / g and 100 g of fly ash having a specific surface area of 5000 cm ² / g, these were dispersed in 1000 cc of water. This dispersion and the above-mentioned viscous liquid were mixed to obtain a solution of the self-hardening composition of the present invention. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

Comparative Example 1 As the hydraulic component (A), a C ₃ A content of 9% by weight and C ₄ AF
Ordinary Portland cement 8 having a mineral composition with a content of 9% by weight, a content of 26% by weight of belite and a content of 50% by weight of alite, and adjusted to a Blaine specific surface area of 3150 cm ² / g
Using 1 g of water, 1800 cc of water was added thereto to obtain a solution of the self-hardening composition. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days. In this composition, bleeding was large and a brittle layer was formed on the upper part of the test piece.

Comparative Example 2 As the hydraulic component (A), a C ₃ A content of 9% by weight and C ₄ AF
Ordinary Portland cement 5 having a mineral composition with a content of 9% by weight, a content of 26% by weight of belite and a content of 50% by weight of alite, and adjusted to a Blaine specific surface area of 3150 cm ² / g
Slag 200 with 00g and brane specific surface area 4000cm ² / g
g, using 12.0 g of a naphthalenesulfonic acid-based fluidizing agent as an admixture (C) and 3.0 g of citric acid as a retarder,
These were dispersed in 1800 cc of water to obtain a solution of the self-hardening composition. Table 1 shows the viscosity of this solution and the compressive strength of the cured product after 1 to 28 days.

[0028]

[Table 1]

As shown in Table 1, Example 1 according to the present invention
Compositions # 6 to # 6 exhibited good viscosity and good flow without material separation. The compression strength of these cured products is 1
Although the strength was low in the initial age of ~ 3 days, rapid strength development was confirmed in the age after 7 days.

Example 7 The composition of Example 1 was used in an amount of 20 parts by weight per 100 parts by weight of mud.
A mud slurry to which parts by weight were added was prepared. Kanto loam was used as mud. This mud slurry has a viscosity of 680
It was 0 cps and showed good initial plastic fluidity. This property was retained after one day. The strength of the composition was observed after 3 days, and showed a compressive strength of 5.1 kgf / cm ² at 28 days.

Example 8 The additive of Example 2 was used in an amount of 25 parts by weight per 100 parts by weight of mud.
A mud slurry to which parts by weight were added was prepared. Kanto loam was used as mud. This mud slurry has a viscosity of 850
It was 0 cps and showed good initial plastic fluidity. This property was retained after one day. Strength development of the composition was observed after 7 days, 2.7 kgf / cm ² at 28 days and 5.6 kgf / c at 91 days.
It showed a compressive strength of m ² .

[0032]

The self-hardening composition of the present invention has an excellent initial plastic fluidity, maintains initial properties for an arbitrary period of time, and hardens.
Thereafter, since it exhibits the necessary and sufficient compressive strength, it exerts an excellent effect as an additive for excavated mud in the mud-type earth pressure shield method.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 14:10 24:26) C09K 103: 00 (72) Inventor Masataka Tsutaka 4-11 Nishinakajima, Yodogawa-ku, Osaka-shi, Osaka No. 27 Hanahara Daini Building Tuck Co., Ltd.

Claims (5)

[Claims] Claims: 1. An additive used in a muddy earth pressure shield method, comprising a hydraulic component as a main component, a hydraulic component and a thickening component, or an admixture together with a hydraulic component and a thickening component. A self-hardening composition characterized by comprising: 2. Hydraulic component (A): 50 to 90% by weight, thickening component (B): 10 to 50% by weight, admixture (C): 0 to 20% by weight
The self-hardening composition according to claim 1, which is: 3. The hydraulic component (A) is cement or a mixture of cement and slag or fly ash, the thickening component (B) is bentonite or clay, the admixture (C) is a viscosity aid, and a fluidizer. Or a retarder.
Self-hardening composition according to the above. 4. The cement of hydraulic component has a content of tricalcium aluminate (3CaO.Al ₂ O ₃ ) of 2 to 7% by weight, and tetracalcium iron aluminate (4CaO.Al ₂ O ₃ —Fe _2). O ₃ ) is 2 to 13% by weight, and the total amount is 5 to 16%.
%, The remaining belite (2CaO.SiO ₂ ) content is 30% by weight or more, and the alite (3CaO.SiO ₂ ) content is 50%.
The self-hardening composition according to any one of claims 1 to 3, which is not more than weight%. 5. A belite (2CaO.SiO ₂ ) content of 50% by weight or more, and an alite (3CaO.SiO ₂ ) content of 40% by weight.
The self-hardening composition according to claim 4, which is: