JPH05202516A - Cement slurry composition for underground continuous wall construction - Google Patents

Abstract

PURPOSE:To prevent bleeding and enhance the strength of underground continuous walls by a method in which a cement slurry composition containing water- soluble synthetic acrylic polymer is impregnated to specified places. CONSTITUTION:An acrylic water-soluble polymer such as reversed phase emulsion of polyacrylamide is added to a cement slurry composed of fresh water or sea water and a cement, and the cement slurry composition is impregnated to construct an underground continuous wall. In this case, the molecular weight and amount of the polymer are selectively adjusted according to the soil quality of the ground so that the surfaces of the cement particles are covered with the polymer, the distance between the cement particles is widened, the settlement of cement particles is suppressed by attracting water around the cement particles, and production of free water is prevented. The occurrence of bleeding can thus be prevented, the strength of hardened cement can be enhanced and the operations can be simplified, while reducing the cost of construction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement-based slurry composition used in an underground continuous wall construction method in civil engineering, particularly a column-row soil cement construction method.

[0002]

2. Description of the Related Art In recent years, excavation methods in civil engineering work have been diversified, and the types of materials and additives used have been diversified. Underground wall construction method in such excavation method,
There are stable liquid construction method and pillar row soil cement construction method. In the stable liquid method, the stable liquid is excavated, the reinforcing bars are inserted into the stable liquid, and then the stable liquid is replaced with cement slurry to form a continuous underground wall having a desired height.

On the other hand, the pillar row soil cement method is
Cement slurry is used in place of the stabilizing solution for excavation, and then reinforcing bars are inserted into the excavated area for hardening. Sunahachi,
By excavating using plastic soil cement and constructing it in the ground, it dries more gently than it does in the ground, and it cures without cracking and under sufficient steam pressure in the ground to cure. Later, a continuous continuous column wall with a watertightness and sufficient strength is obtained.

This column-row soil cement construction method includes 1) in-situ excavation stirring and hardening system, 2) soil cement displacement hardening system, and 3) mud solidification system. Further subdivide 1)
Among them are a) a method with a stirring wing and auger, and b) a stirring method with a high-pressure jet. Furthermore, among the construction methods of b), there are SMW construction method, MIP construction method, TSP construction method, RRO construction method.
Construction method, N-SC construction method, MSP construction method, YSW construction method, Tenocolumn construction method, CMC construction method, DJM construction method, Demic-L construction method, Oval-DM construction method, SBW construction method, JST construction method, etc. Construction method, column jet grout construction method, JSG construction method, JMM construction method, SSS-
There is a MAN method etc. Also, in 2), PIPL
There are construction methods, etc., and within 3) SG-H construction method, FUS
There are S method, K-WH method, FSW method and the like.

Each of these construction methods is common to use a cement-based slurry. The cement-based slurry to be used is made of fresh water or seawater as a solvent, and the solvent 100
20 parts by weight to 250 parts by weight of cement is added to parts by weight.

Further, as the cement-based slurry for the pillar row soil cement method, 0 to 50 parts by weight of bentonite and / or 0 to 5 parts by weight of a cement dispersant and 100% by weight of the cement-based slurry, and some other additives are used. A composition modified by adding, for example, is used.

[0007] Water-soluble celluloses, starch ethers, superabsorbent resins, organic compounds such as polyethylene oxide or sodium aluminate, alkali metal carbonates, attapulgite, etc. have the same function as the bentonite used here. Inorganic compounds (hereinafter referred to as bentonites). Examples of the cement dispersant include lignin-based compounds such as lignin sulfonate or its modified product, naphthalene-based compounds such as naphthalene sulfonate or its condensate, and melamine-based compounds such as melamine sulfonic acid formalin condensate. The purpose of using these additives is to improve the fluidity of the cement-based slurry and to minimize the generation of free water (hereinafter referred to as breathing) due to sedimentation and separation of cement particles.

[0008]

However, in the conventional cement-based slurry composition to which bentonites and / or cement dispersants are added, a bleeding phenomenon occurs during the hardening process of the cement-based slurry, and free water is generated. It cannot be avoided.

In order to reduce the breathing, conventionally, methods such as increasing the amount of bentonites added or reducing the proportion of cement water by adding a cement dispersant have been adopted. However, bentonites
Due to the influence of cement or seawater, its activity is reduced and it becomes impossible to obtain a sufficient effect for preventing breathing.

Therefore, in the column-row soil cement construction method using these cement-based slurry compositions, after the cement-based slurry used is hardened, free water (breathing rate of 10 to 20) generated in the hardening process is generated. %) Is discharged, and a new cement-based slurry is poured into the voids of the portion where the free water is discharged and removed, and then hardened by performing a two-step construction, and the underground column continuous wall of the desired height is obtained. Was being made.

As described above, the occurrence of the breathing phenomenon is
This is not preferable because it complicates the work or increases the cost. Therefore, as a result of intensive studies, the present inventors intend to provide a cement-based slurry composition that does not cause a breathing phenomenon in the curing process.

[0012]

The present invention provides a cement-based slurry 100 obtained by adding and mixing 20 parts by weight to 250 parts by weight of cement to 100 parts by weight of fresh water or seawater used in a pillar row soil cement construction method. Parts by weight,
The acrylic water-soluble synthetic polymer is preferably 0.01 to
The present invention provides a cement-based slurry composition for an underground continuous wall construction method, which comprises 6.0 parts by weight, more preferably 0.05 to 2.0 parts by weight.

Examples of the acrylic water-soluble synthetic polymer include acrylamide (methacrylamide), acrylic acid (methacrylic acid) or their alkali metal salts, methacrylamidopropyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride and dimethylaminopropyl. Polymerization product obtained from one or more selected from monomers such as acrylamide quaternary ammonium salt, N-methylol acrylamide, methylol methacrylamide, and other acrylates (methacrylic acid esters) or A copolymer, or a mixture of two or more selected from these polymers or copolymers can be used.

These acrylic water-soluble synthetic polymers can be synthesized by a polymerization method such as a radical polymerization method or a light polymerization method using a redox initiator. However, there is no limitation to these polymerization methods. Absent.

The acrylic water-soluble synthetic polymer may be in the form of powder or liquid. In the liquid,
In addition, there are forms of aqueous solution or reverse emulsion,
From the viewpoints of workability and effect, the form of the reverse emulsion is advantageous from the viewpoint of comprehensive evaluation. In the form of an inverse emulsion, the type and amount of the oil phase and the type and amount of the surfactant used for the emulsion are not particularly limited.

The acrylic water-soluble synthetic polymer may be added either before or after the cement slurry is prepared. That is, a method in which a necessary amount of an acrylic water-soluble synthetic polymer is dissolved in fresh water or seawater in advance and cement is added to the solution, or a cement is added to fresh water or seawater to prepare a slurry, and then the acrylic water-soluble synthetic polymer is added. The slurry composition of the present invention can be obtained by, for example, a method in which a powder obtained by preliminarily adding and mixing and cement is added to fresh water or seawater. In any addition order, the effect of preventing occurrence of breathing is excellent.

The molecular weight of the above acrylic water-soluble synthetic polymer is preferably 2,000,000 to 20,000,000, more preferably 4,000,000 to 12,000,000. Within these molecular weight ranges, the optimum molecular weight is determined by the polarity of the polymer.

[0018]

With the conventional cement-based slurry, breathing occurs during the process of hardening in the ground. Therefore, it is necessary to perform work such as discharging free water and newly injecting cement slurry into the void, which complicates the work, and the strength of the underground column may differ between the lower part and the upper part. A structure which is not preferable as a medium continuous wall will be formed.

On the other hand, in the composition of the present invention, the cement-based slurry used during underground excavation in the pillar-row soil cement method does not cause breathing during the process of hardening in the ground, and has a sufficient strength. Forming a cured body having. That is, according to the present invention, the acrylic water-soluble synthetic polymer covers the surface of the cement particles, spreads the space between the cement particles, further, by attracting the water around the cement particles, sedimentation of the cement particles in the cement-based slurry It is thought to prevent the generation of free water.

On the other hand, the acrylic water-soluble synthetic polymer used in the present invention is well dissolved in fresh water or seawater and exhibits a thickening effect. The thickening effect varies depending on the molecular weight and concentration of the polymer. Therefore, the optimum composition of the cement-based slurry composition can be selected by adjusting and selecting the molecular weight of the acrylic water-soluble synthetic polymer and also by selecting the addition amount, and the cement-based slurry composition suitable for the soil of the excavated ground can be selected. Things can be adjusted.

That is, the amount of the acrylic water-soluble synthetic polymer added to the cement slurry is not particularly limited, but is preferably 0.01 to 6.0 parts by weight, more preferably 0.05 to 2. 0 parts by weight.

Further, the characteristics of the slurry have been adjusted by adding bentonite as a thickening agent, a cement dispersant as a flow adjusting agent and some other additives to a conventional cement-based slurry. On the other hand, in the composition of the present invention, the characteristics of the slurry can be adjusted only by adding a preselected acrylic water-soluble synthetic polymer to the cement-based slurry.

Further, in the composition of the present invention, the effect of preventing breathing can be further enhanced by using bentonites and a cement dispersant together with the acrylic water-soluble synthetic polymer.

Furthermore, the composition of the present invention does not deteriorate its bleeding preventing effect even if commonly used aggregates such as gravel, fly ash, and other lightweight aggregates are added.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 50 parts by weight of normal Boltland cement was added to 50 parts by weight of fresh water, and the mixture was stirred for 2 minutes by a lab stirrer. Then, a polyacrylamide reverse phase emulsion liquid (active ingredient 36%, average molecular weight about 5 million) was added to 0. 0.5 parts by weight, 1.
Add 0 parts by weight each and stir for another 2 minutes,
The bleeding rate after standing at room temperature for 24 hours and the uniaxial compressive strength after standing at room temperature for 72 hours were measured. The measurement results are shown in Table 1. Breathing rate = (W / K) × 100 W: Free water amount (ml) K: Cement-containing sedimentation sludge amount (ml)

Example 2 An example using a reverse phase emulsion liquid of polyacrylic acid / acrylamide copolymer (active ingredient 32.5%, average molecular weight 4.2 million) in place of the polyacrylamide reverse phase emulsion liquid in Example 1 The measurement was performed in the same manner as 1. The measurement results are shown in Table 1.

Example 3 The same measurement as in Example 1 was carried out using seawater instead of the fresh water in Example 1. The measurement results are shown in Table 1.

Example 4 The same measurement as in Example 2 was carried out by using seawater instead of the fresh water in Example 2. The measurement results are shown in Table 1.

Comparative Example 1 50 parts by weight of normal boltland cement was added to 50 parts by weight of fresh water, and the mixture was stirred with a lab stirrer for 2 minutes. Then, 10.0 parts by weight of bentonite and 1. parts of a ligninsulfonic acid type cement dispersant were added. 5 parts by weight of each was added and stirred for 2 minutes, and as in Example 1, the breathing rate after standing at room temperature for 24 hours and the uniaxial compressive strength after standing at room temperature for 72 hours were measured. The measurement results are shown in Table 1.

Comparative Example 2 The same measurement as in Comparative Example 1 was carried out using seawater instead of the fresh water in Comparative Example 1. The measurement results are shown in Table 1.

[0031]

[Table 1]

From the results shown in Table 1, the cement-based slurry compositions of Examples 1 and 2 to which the acrylic water-soluble synthetic polymer was added showed less occurrence of breathing and the obtained cured product had excellent strength. I understand.

[0033]

EFFECTS OF THE INVENTION The cement-based slurry composition for underground wall construction method of the present invention does not cause bleeding in the process of hardening the cement-based slurry, and the obtained hardened product has sufficient strength.

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[Procedure amendment]

[Submission date] March 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

On the other hand, the pillar row soil cement method is
Cement slurry is used in place of the stabilizing solution for excavation, and then reinforcing bars are inserted into the excavated area for hardening. Sunahachi,
By excavating using plastic soil cement and constructing it in the ground, it will dry more gently than on the ground, will not crack, and will be cured under sufficient steam pressure in the ground to ensure that it is cured. Obtain a continuous continuous column wall with watertightness and sufficient strength.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

In order to reduce the breathing, conventionally, methods such as increasing the amount of bentonites added or reducing the ratio of water to cement by adding a cement dispersant have been adopted. However, the activity of bentonites is reduced due to the influence of cement and seawater, and a sufficient effect for preventing breathing cannot be obtained.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Therefore, in the column-row soil cement construction method using these cement-based slurry compositions, after the cement-based slurry used is hardened, free water (breathing rate 10 to 20%) generated in the hardening process is removed. After discharging and removing, and injecting a new cement-based slurry into the voids of the part where the free water was discharged and removed, hardening is performed, and two-step construction is performed to create an underground pillar row continuous wall of the desired height. Was there.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction] The above acrylic water-soluble synthetic polymers include acrylamide (methacrylamide), acrylic acid (methacrylic acid) or their alkali metal salts, methacrylamidopropyltrimethylammonium chloride,
Methacryloyloxyethyl trimethyl ammonium chloride, dimethylaminopropyl acrylamide No. 4
Polymers or copolymers obtained from one or more selected from monomers such as primary ammonium salts, N-methylol acrylamide, methylol methacrylamide, and other acrylic acid esters (methacrylic acid esters) Alternatively, a mixture of two or more selected from these polymers or copolymers can be used.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The acrylic water-soluble synthetic polymer may be added either before or after the cement slurry is prepared. That is, a method in which a necessary amount of an acrylic water-soluble synthetic polymer is dissolved in fresh water or seawater in advance and cement is added to the solution, or a cement is added to fresh water or seawater to prepare a slurry, and then the acrylic water-soluble synthetic polymer is added. The slurry composition of the present invention can be obtained by a method of adding a required amount of the above, or a method of adding a powder in which a powdery acrylic water-soluble synthetic polymer and cement have been added and mixed in advance to fresh water or seawater. Even in the order of addition, the effect of preventing the occurrence of breathing is excellent.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 50 parts by weight of normal Boltland cement was added to 50 parts by weight of fresh water, and the mixture was stirred for 2 minutes by a lab stirrer. Then, a polyacrylamide reverse phase emulsion liquid (active ingredient 36%, average molecular weight about 5 million) was added to 0. 0.5 parts by weight, 1.
Add 0 parts by weight each and stir for another 2 minutes,
The bleeding rate after standing at room temperature for 24 hours and the uniaxial compressive strength after standing at room temperature for 72 hours were measured. The measurement results are shown in Table 1. Breathing rate = (W / K) × 100 W: Free water amount after 24 hours (ml) K: Cement slurry amount (ml)

Claims (1)

[Claims] 1. A cement-based slurry composition for a continuous underground wall construction method, which comprises an acrylic water-soluble synthetic polymer added to a cement-based slurry.