JP2954136B2 - Ground improvement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method. More specifically, the present invention relates to a soil improvement method when the mixing of soil and soil improvement material is not uniform. According to the method of the present invention, even when the soil and the soil improvement material are not sufficiently uniformly mixed, a part of the soil improvement material does not set and harden prematurely, and thus hinders a smooth progress of the civil engineering work. Can be prevented.

[0002]

2. Description of the Related Art In the prior art, for example, when a pile is wrapped, a pile is prepared using cement milk to which bentonite, a thickening agent, a setting retarder, and the like are added, and the next day, the pile is prepared. Hardened pile-forming cement milk is mechanically agitated mechanically, on top of which cement milk is added,
The continuity of the wrap was ensured. If such a construction method cannot be carried out and one pile cannot be improved with the amount of construction per day, it is necessary to cast steel pipe piles instead of concrete piles, which increases costs. Cause problems.

[0003] Even in the case of soil improvement, in the method of injecting cement milk into the soil in the ground and kneading the same in the ground, it is impossible to check the quality of the kneading condition. In this case, a cement milk layer released from the soil is formed. In this case, cement milk that is sufficiently mixed with soil reduces the amount of cement milk per unit volume of ground due to contamination of soil,
Due to the reaction between the cement component and the soil, etc., the setting and the delay in the development of strength can be obtained.However, the portion of the cement milk that is not mixed with the soil will set and harden more rapidly than the portion that is mixed with the soil. However, this would hinder the smooth extension of civil works.

[0004] Further, even when a slow-hardening material is used as the hardening material, such a slow-hardening material milk can maintain an unhardened state for about one day in a state where it is not mixed with soil. It is difficult to maintain the uncured state for an extended period of days.

In the prior art, for example, Japanese Patent Publication No. 3-2
No. 6237 discloses that 5 to 15% by weight of a hydraulic cement having a specific Blaine specific surface area and a specific fineness is 65 to 80% by weight of a latent hydraulic substance having a specific Blaine specific surface area and a specific fineness, and gypsum. -20% by weight, and if necessary, a solidifying material for ground improvement prepared by adding an admixture such as a retarder or a water reducing agent to the soil of the soft underwater ground at a ratio of 15-20% by weight. , A method of solidifying.

Japanese Patent Application Laid-Open No. 60-135478 discloses 60-70% by weight of 3CaO.SiO ₂ and 4% by weight or less of 3CaO as a solidifying material for soft ground stabilization.
· Comprises Al ₂ O _3, comprising: a Portland cement 20-50 wt% having a specific fineness and 50 to 80 wt% blast furnace slag, if necessary, containing 2% by weight of setting retarder, with the compositions It has been shown.

However, in these prior arts, when the solidified material is not sufficiently uniformly mixed with the soil, the portion of the solidified milk mixed with the soil and the portion not mixed with the soil are different from each other. At the setting speed, it solidifies and develops strength, so that the solidified material-injected soil portion cannot be uniformly solidified at the desired setting speed, and the progress of civil engineering work cannot be smoothed. There is no teaching or suggestion as to the solution.

[0008]

SUMMARY OF THE INVENTION The present invention can delay the setting of cement milk over a required period of time when the mixing of the soil and the soil improvement material is not uniform, thereby facilitating the progress of civil engineering work. It is an object of the present invention to provide a ground improvement method that can be performed.

[0009] The soil improvement method (1) of the present invention can be applied to a case where the mixing of the soil and the soil improvement material is not uniform.
99 and plaster powder blast-furnace slag powder and 0 to 20 parts by weight parts by weight, the solidifying material is dispersed in water containing a Portland cement 30 parts by weight having a fineness Blaine value of 1350~5000cm ² / g In preparing the solidified milk, the solidified milk is added to the solidified milk in an amount of 0.1 to 5.0% based on the weight of the solidified material, such as an organic acid salt, an organic acid, a polymer complex, an organic derivative, a saccharide, and a silica gel. A setting retarder comprising at least one selected from the group consisting of chlorides, borates, and phosphates, and mixing the mixed milk with soil to solidify.

The soil improvement method (2) according to the present invention is characterized in that, when the soil and the soil improvement material are not mixed uniformly, 50 to 98 parts by weight of blast furnace slag powder and 0 to 20 parts by weight of gypsum powder are used. , 1350~5000cm ² / g fineness dispersed solidifying material milk solidifying material in water containing a 1-20 cement hydrate Portland cement and 1-10 parts by weight of finely divided powder having a Blaine value When preparing the solidified milk, the solidified milk is further made to contain 0.1 to 5.0% of a setting retarder with respect to the weight of the solidified material, and the mixed milk is mixed with the soil and solidified. It is assumed that.

The soil improvement method (3) according to the present invention is characterized in that, when the soil and the soil improvement material are not mixed uniformly, 70 to 99 parts by weight of blast furnace slag powder and 0 to 20 parts by weight of gypsum powder are used. When preparing a solidified material milk by dispersing a solidified material containing 1 to 10 parts by weight of fine particles of cement hydrate in water, the solidified material milk is added in an amount of 0.1 to the weight of the solidified material. ~ 5.0% of a set retarder, and the mixed milk is mixed with the soil and solidified.
It is characterized by the following.

In each of the soil improvement methods (2) and (3) of the present invention, the setting retarder is an organic acid salt such as ligninsulfonate, or an organic acid such as citric acid or 2-ketogluconic acid. Acids, polymer complexes such as polyol polymer complexes, organic derivatives such as lignin sulfonic acid derivatives, sugars such as glucose and sucrose, silicates, borates and phosphates as examples It is preferable that it is composed of at least one selected from inorganic salts.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, generally, when the soil and the soil improvement material are not sufficiently uniformly mixed, for example, in the case of the deep mixing method, a solidified material containing a predetermined component is dispersed in water. To prepare the solidified milk,
The solidified milk was added to the solidified milk in an amount of 0.1
５5.0%, preferably 0.4-2.0%, of a setting retarder is added and mixed, and the mixed milk is mixed with the soil in the ground to be improved and solidified. In the method of the present invention, in the portion of the mixed milk mixed with the soil, the setting retarder is adsorbed on the soil, and the setting delay effect is reduced or lost, but the mixed milk is diluted by the soil, and the solidified material is further reduced. The slow setting properties of the composition itself, together with the setting retardation effect, indicate a desired delayed setting rate. Also, the portion of the mixed milk that does not mix with the soil does not adsorb the set retarder to the soil, and thus exhibits the desired set retarding effect even if the mixed milk is not diluted by the soil. Therefore, in the method of the present invention, both the portion of the mixed milk mixed with the soil and the portion not mixed show the setting delay effect, and the required civil engineering work can be smoothly advanced.

The solidified material (1) used in the soil improvement method (1) according to the present invention is 50 to 99 parts by weight, preferably 7 to 99 parts by weight.
0-95 parts by weight of blast furnace slag and 0-20 parts by weight, preferably 0-15 parts by weight of gypsum powder, 1350-500
0 cm ² / g, preferably 1 to 30 parts by weight having a fineness Blaine value of 1350~3500cm ² / g, preferably those containing Portland cement 5 to 15 parts by weight, these solidifying material in water In preparing the solidified milk by dispersing, 0.15 to 5.0% of the organic acid salt, organic acid, polymer complex, organic derivative, saccharide, It further contains a set retarder consisting of one or more selected from silicon fluoride, borate and phosphate. The solidified material (1) thus obtained can be easily dispersed in water to form solidified material milk.

[0015] In the solidified material (1) used in the method (1) of the present invention, if the content of the blast furnace slag powder is less than 50 parts by weight, there is an inconvenience of poor setting delay of the portion of the mixed milk mixed with the soil. If the amount exceeds 99 parts by weight, there is a disadvantage that the solidification effect of the solidified material is poor. The blast furnace slag powder used for the solidifying material (1) preferably has a fineness Blaine value of 1500 to 5000 cm ² / g. There is no particular limitation on the type of gypsum used for the solidifying material (1), and gypsum dihydrate, gypsum hemihydrate,
Or, it can be selected from anhydrous gypsum or the like, but general drainage gypsum can be used. Also 1500 to 500
It is preferable to use one having a fineness (Brain value) of about 0 cm ² / g. When the content of the gypsum powder exceeds 20 parts by weight, there is a disadvantage that the setting delay of the portion mixed with the soil and the portion not mixed is poor and the strength of the long-term age is poor.

In the solidified material (1) used in the method (1) of the present invention, the content of Portland cement is 1
If the amount is less than 1 part by weight, there is a disadvantage that the solidifying material has a poor soil solidifying action.
If the amount is more than 0 parts by weight, there is a disadvantage that the setting delay of the mixed portion and the unmixed portion of the mixed milk is poor. The Portland cement referred to here is a raw material (clinker, gypsum), and the manufacturing method conforms to Portland cement (JISR5210). Not something. The Portland cement contained in the solidifying material (1) may be any Portland cement other than the ultra-high strength Portland cement, such as ordinary Portland cement, moderate heat Portland cement,
At least one selected from low heat Portland cement, sulfate resistant Portland cement and the like can be used. The Portland cement contained in the solidifying material (1) has a fineness Blaine value of 1350 to 5000 cm ² / g. When this value is less than 1350 cm ² / g, there is a problem that the solidification effect of the solidified material is poor, and when it exceeds 5000 cm ² / g, the setting delay of the portion of the mixed milk mixed with the soil is poor. This causes inconvenience. Examples of the setting retarder used in the method (1) of the present invention include organic acid salts such as ligninsulfonate, oxycarboxylate, hydroxycarboxylate, gluconate, aromatic sulfonate, oxycarboxylic acid, amino acid and the like. Organic acids such as carboxylic acid, lactic acid, tartaric acid, citric acid, 2-ketoglutaric acid, and 2-ketogluconic acid, polyol-based polymer complex, complex of modified lignin and oxycarboxylic acid compound, complex of highly modified polyol and glycitol derivative Polymer, complex of modified polyol and polycarboxylic acid ether, complex of modified lignin sulfonic acid compound and oxycarboxylic acid, polymer complex such as hydroxy polymer complex, lignin sulfonic acid derivative, organic acid derivative ,
Modified lignin sulfonic acid from at least one of known organic retardants such as high molecular weight cellulose derivatives, sugars such as glucose, sucrose, sorbitol, pentaerythritol, silicon fluoride, phosphate, and borate. Is used. In the method (1) of the present invention, the solidified material (1) is dispersed in water to form a solidified material milk, and the milk has a specific coagulation amount of 0.1 to 5.0% by weight of each solidified material. A retarder is further included to form the mixed milk. If the addition amount of the setting retarder is less than 0.1%, the setting of the portion of the mixed milk that has not been sufficiently mixed with the soil becomes faster, and the setting delay effect becomes insufficient as a whole. It is 5.0%
If it exceeds 300, there is a disadvantage that the solidification effect of the soil after the delay in setting is poor. In the method (1) of the present invention, in order to mix the mixed milk with the soil, a conventionally known method such as a deep mixing method may be used. The mixed milk used in the method (1) of the present invention is prepared by preparing a solidified material (1) containing a predetermined component in advance and adding and mixing a setting retarder during dispersion in water. Alternatively, a setting retarder may be added and mixed in advance to each solidified material, and the mixture may be prepared by dispersing it in water.Or, each component may be mixed at the time of use and dispersed in water. May be prepared.

The solidification material (2) used in the soil improvement method (2) of the present invention is 50 to 98 parts by weight, preferably 75 to 98 parts by weight.
90 parts by weight of blast furnace slag powder and 0 to 20 parts by weight, preferably 0 to 15 parts by weight of gypsum powder, and 1350 cm ² / g
~ 5000 cm ² / g, preferably 1350-3500 cm
1-20 parts by weight, preferably 5-10 parts by weight, of Portland cement having a fineness Blaine value of ² / g, and 1-10 parts by weight, preferably 5-10 parts by weight, of fine powder of cement hydrate. Is included. Such solidifying material (2) readily disperses in water to form solidified milk.

In the solidified material (2) used in the method (2) of the present invention, when the content of the blast furnace slag powder is less than 50 parts by weight, the setting delay of the portion of the mixed milk mixed with the soil and the portion of the mixed milk not mixed is prevented. If the amount exceeds 98 parts by weight, the soil solidifying action of the solidified material will be disadvantageous. The blast furnace slag powder used for the solidified material (2) has a fineness Blaine value of 150.
It is preferably from 0 to 5000 cm ² / g. Further, this gypsum can be selected from gypsum dihydrate, gypsum hemihydrate and gypsum anhydrous, but gypsum gypsum is preferably used, and general gypsum plaster can be used. Fineness Blaine value is 1
It is preferably from 500 to 5000 cm ² / g. When the content of the gypsum powder exceeds 20 parts by weight, there is a disadvantage that the setting delay of the portion mixed with the soil and the portion not mixed is poor and the strength of the long-term age is poor.

In the solidified material (2) used in the method (2) of the present invention, the content of Portland cement is 1
If the amount is less than 1 part by weight, the solidification effect of the solidified material becomes poor, and if it exceeds 20 parts by weight, the setting delay of the portion mixed with the soil of the mixed milk is caused. Inconvenience of failure occurs. The Portland cement contained in the solidifying material (1) may be any Portland cement except for the ultra-high strength Portland cement, such as ordinary Portland cement, moderately heated Portland cement, low-heat Portland cement,
At least one selected from sulfate-resistant Portland cement and the like can be used. Portland cement contained in the solidifying material (2) is 1350 to 5000
It has a fineness Blaine value of cm ² / g. When this value is less than 1350 cm ² / g, there is a disadvantage that the solidification effect of the solidified material is poor, and it is 500
If it exceeds 0 cm ² / g, there is a problem that the setting and hardening of the portion of the mixed milk mixed with the soil and the portion not mixed are poor in setting and hardening.

The solidifying material (2) used in the method (2) of the present invention contains 1 to 10 parts by weight of a fine powder of cement hydrate. The cement hydrate is a cement hydrate obtained from concrete sludge, a cement hydrate obtained from hardened concrete, and / or a cement hydrate obtained by adding water to a cement and causing a hydration reaction. Fine particles can be used. The fineness of the cement hydrate is preferably from 0.4 to 10 m ² / g by the BET method (surface area measurement method by gas adsorption). In the solidified material (2) used in the method (2) of the present invention, when the content of the fine cement hydrate powder is less than 1 part by weight, the effect of the solidified material on the soil solidification effect and the effect of promoting the inseparability of the mixed milk are small. When the amount exceeds 10 parts by weight, the setting delay of the portion mixed with the soil of the mixed milk and the portion not mixed is caused.

The solidified material (3) used in the method (3) of the present invention comprises 70 to 99 parts by weight, preferably 75 to 95 parts by weight, of blast furnace slag powder and 0 to 20 parts by weight, preferably 0 to 15 parts by weight. Parts of gypsum powder and 1 to 10 parts by weight, preferably 5 to 10 parts by weight, of fine particles of cement hydrate. Such a solidifying material (3) is easily dispersed in water to form a solidifying material milk.

In the solidified material (3) used in the method (3) of the present invention, when the content of the blast furnace slag powder is less than 70 parts by weight, the setting delay of the portion of the mixed milk mixed with the soil and the portion of the mixed milk not mixed is prevented. However, if it exceeds 99 parts by weight, the solidification material has a problem of poor soil solidification action. The fineness Blaine value of the blast furnace slag powder used for the solidified material (3) is 1500
Preferably it is ~ 5000 cm < ² > / g. The gypsum can be selected from gypsum dihydrate, gypsum hemihydrate or anhydrous gypsum, but gypsum dihydrate is preferably used, and general drained gypsum can be used. The fineness Blaine value is preferably from 1500 to 5000 cm ² / g. When the content of the gypsum powder exceeds 20 parts by weight, there is a disadvantage that the setting delay of the portion not mixed with the soil and the mixed portion is poor and the strength at the long-term age is poor.

The solidified material (3) used in the method (3) of the present invention contains 1 to 10 parts by weight of a fine powder of cement hydrate. This cement hydrate is a fine particle of a cement hydrate obtained from concrete sludge, a cement hydrate obtained from hardened concrete, and / or a cement hydrate obtained by adding water to a cement to cause a hydration reaction. Particles can be used. The fineness of the cement hydrate is preferably from 0.4 to 10 m ² / g by the BET method (surface area measurement method by gas adsorption). In the solidified material (3) used in the method (3) of the present invention, when the content of the fine cement hydrate powder is less than 1 part by weight, the effect of the solidified material on the soil solidification effect and the effect of promoting the inseparability of the mixed milk are small. If the amount exceeds 10 parts by weight, the setting delay of the portion of the mixed milk mixed with the soil is poor.

The setting retarder used in each of the methods (2) and (3) of the present invention includes a lignin sulfonate, an oxycarboxylate, a hydroxycarboxylate, a gluconate, an aromatic sulfonate and the like. Organic acid salts, oxycarboxylic acids, aminocarboxylic acids, lactic acid, tartaric acid, citric acid,
Organic acids such as 2-ketoglutaric acid and 2-ketogluconic acid, polyol polymer composites, composites of modified lignin and oxycarboxylic acid compounds, composites of highly modified polyols and glycitol derivatives, modified polyols and polycarboxylic acid ethers Complex, complex of modified lignin sulfonic acid compound and oxycarboxylic acid, polymer complex such as hydroxy polymer complex, lignin sulfonic acid derivative, organic acid derivative, modified lignin sulfonic acid polymer cellulose derivative, etc. And at least one known set retarding compound such as an organic derivative of the above, sugars such as glucose, sucrose, sorbitol and pentaerythritol, and inorganic salts such as silicon fluoride, phosphate and borate.

In each of the methods (2) and (3) of the present invention, each of the solidifying agents (2) and (3) is dispersed in water to form a solidifying agent milk. Further, 0.1 to 5.0% by weight of the set retarder is further included to form a mixed milk. When the addition amount of the setting retarder is less than 0.1%, the setting of the portion of the mixed milk that has not been sufficiently mixed with the soil becomes faster, and as a whole,
The setting retardation effect becomes insufficient. On the other hand, if it exceeds 5.0%, there is a disadvantage that the solidification effect of the soil after setting delay is poor.

In each of the methods (2) and (3) of the present invention, the mixed milk may be mixed with the soil by a conventionally known method, for example, a deep mixing method.

The mixed milk used in each of the methods (2) and (3) of the present invention is prepared by preparing each of the solidified materials (2) and (3) containing predetermined components in advance, It may be prepared by adding and mixing a setting retarder during dispersion,
A setting retarder may be added and mixed in advance to each solidified material, and the mixture may be prepared by dispersing it in water.Or, each component may be mixed at the time of use and dispersed in water. You may.

[0028]

The present invention is further described by the following examples.

Examples 1 to 3 and Comparative Example 1 In each of Examples 1 to 3 and Comparative Example 1, according to the composition shown in Table 1, mixed milk (with retarder added) and solidified milk (without retarder) In addition, mixed milk of each of the above milk and soil (hereinafter referred to as soil mixed milk) was prepared. Note that a mixed milk containing a predetermined amount of a retarder and a soil mixed milk obtained by mixing the mixed milk and the soil are examples of the present invention.
Solidified milk without a retarder and soil-mixed milk obtained by mixing the same with soil are comparative examples. (1) Solidifying material Cement, name: ordinary Portland cement Fineness Blaine value: 1360 cm ² / g Blast furnace slag powder, specific gravity: 2.92 Fineness: 4040 cm ² / g Plaster, specific gravity: 2.95 Fineness: 1890 cm ² / g (2) Setting retarder: Name: Pozuris No. 89 component: complex of modified lignin and oxycarboxylic acid compound (3) Weight ratio of water to solidified material (W / C) in mixed milk or solidified material milk = 60%, addition of setting retarder in mixed milk The amount is% by weight based on the total weight of the solidified material. However, the weight ratio of water and solidified material is 60%
The reason for this is to avoid the influence of material separation. (4) soil mixing milk, using a marine silt as soil, the weight ratio of the relative soil 1 m ^3, was added solidifying material of 300 kg (not including retarder), water and the solidifying material (W / C) Is 1
It was 50% by weight. In consideration of the fact that the above value is usually 40 to 200% in the deep mixing method, the weight ratio (W / C) between the water and the solidified material is set to 150% by weight. The amount of the setting retarder added was 0.4, 1.0, and 2.0% by weight based on the total weight of the solidified material. (5) Table 1 shows the relationship between the age and the compressive strength when the mixed milk, solidified material milk and soil mixed milk were sealed and cured in a 20 ° C constant temperature curing room.

[0030]

[Table 1]

As is clear from Table 1, when the setting retarder was not added, the strength was observed after 3 days of the solidified milk and 7 days after the soil mixed milk. On the other hand, when the setting retarder is added, the expression of the strength of the mixed milk and the soil mixed milk is reliably delayed after the age of 7 days. Moreover, when the amount of the setting retarder added increases, the strength expression of the mixed milk is certainly delayed, but the strength of the 28-year-old soil mixed milk is not lower than that without the addition.

[0032] In each of Examples 4 and 5 Examples 4 and 5, the compositions listed in Table 2, mixed milk was prepared solidifying material milk and the soil mixed milk. (1) Solidifying material Cement, name: Ordinary Portland cement Fineness 1360 cm ² / g Fine particles of cement hydrate (prepared from concrete sludge) Specific gravity 2.25 Fineness 0.8cm ² / g Blast furnace slag powder, specific gravity 2. 88 Fineness Blaine 4020 cm ² / g Plaster, specific gravity 2.95 Fineness 3670 cm ² / g (2) Setting retarder 89 component: complex of modified lignin and oxycarboxylic acid compound (3) Weight ratio of water to solidified material (W / C) in mixed milk or solidified material milk = 60%, addition of setting retarder in mixed milk The amount is% by weight based on the total weight of the solidified material. However, the weight ratio of water and solidified material is 60%
The reason is to avoid adverse effects due to material separation. (4) soil mixing milk, using a marine silt as soil, the weight ratio of the relative soil 1 m ^3, was added solidifying material of 300 kg (not including retarder), water and the solidifying material (W / C) Is 1
It was 50% by weight. In consideration of the fact that the above value is usually 40 to 200% in the deep mixing method, the weight ratio (W / C) between the water and the solidified material is set to 150% by weight. The addition amount of the setting retarder was 0.4% by weight based on the total weight of the solidified material. (5) Table 2 shows the relationship between the age and the compressive strength when the mixed milk, solidified material milk and soil mixed milk were sealed and cured in a 20 ° C constant temperature curing room.

[0033]

[Table 2]

As is clear from Table 2, when the cement and cement-hydrated cement hydrate described in claim 2 are used as a stimulant, when a setting retarder is added,
In both mixed milk and soil mixed milk, the development of strength is reliably delayed after 7 days of age. In addition, the solidification strength at the age of 14 days is slightly lower than that at the time of no addition, but the strength at the age of 28 days is equal to or higher than that without the addition.

Example 6 Mixed milk, solidified milk and mixed soil milk were prepared from the compositions shown in Table 3. (1) Solidifying agent Fine particles of cement hydrate (prepared from concrete sludge) Specific gravity 2.25 Fineness 0.8 cm ² / g Blast furnace slag powder, specific gravity 2.92 Fineness Blaine 4400 cm ² / g Plaster, specific gravity 2 .95 Fineness: 3670 cm ² / g (2) Setting retarder 89 component: complex of modified lignin and oxycarboxylic acid compound (3) Weight ratio of water to solidified material (W / C) in mixed milk or solidified material milk = 60%, addition of setting retarder in mixed milk The amount is% by weight based on the total weight of the solidified material. However, the weight ratio of water and solidified material is 60%
The reason is to avoid adverse effects due to material separation. (4) soil mixing milk, using a marine silt as soil, the weight ratio of the relative soil 1 m ^3, was added solidifying material of 300 kg (not including retarder), water and the solidifying material (W / C) Is 1
It was 50% by weight. In consideration of the fact that the above value is usually 40 to 200% in the deep mixing method, the weight ratio (W / C) between the water and the solidified material is set to 150% by weight. The amount of the setting retarder added was 0.4% by weight based on the total weight of the solidified material. (5) Table 2 shows the relationship between the age and the compressive strength when the mixed milk, solidified material milk and soil mixed milk were sealed and cured in a 20 ° C constant temperature curing room.

[0036]

[Table 3]

As is clear from Table 3, when the solidifying material containing cement hydrate as a stimulant according to claim 3 is used, when a setting retarder is added, both mixed milk and soil mixed milk can be obtained. The development of strength is reliably delayed after 7 days of material age. However, the strength of the soil-mixed milk at the age of 28 days is reduced to half or less as compared with the case where no additive is added, but at the age of 56 days, the intensity becomes considerably close to the strength of the 28-day-old material.

Examples 7 to 10 and Comparative Examples 2 to 5 In Examples 7 to 10 and Comparative Examples 2 to 5,
The solidified milk and the mixture of the solidified milk and the soil were prepared by the composition described in (1). However, the cement described in Example 1 had a fineness Blaine value of 3270 cm.
² / g. (1) Solidifying material Cement, name: ordinary Portland cement Fineness: 3270 cm ² / g Blast furnace slag powder, specific gravity 2.90 Fineness: Blaine value 4150 cm ² / g Setting retarder 89 Ingredients: Complex of modified lignin and oxycarboxylic acid compound (2) Weight ratio (W / C) of water and solidified material in mixed milk or solidified milk = 60%, addition of setting retarder in mixed milk The amount is% by weight based on the total weight of the solidified material. However, the weight ratio of water and solidified material is 60%
The reason is to avoid adverse effects due to material separation. (3) Soil-mixed milk uses marine silt as soil, and 300 kg of solidifying agent (not including a retarder) is added to 1 m ^{3 of} soil, and the weight ratio of water to solidifying agent (W / C) Is 1
It was 50% by weight. In consideration of the fact that the above value is usually 40 to 200% in the deep mixing method, the weight ratio (W / C) between the water and the solidified material is set to 150% by weight. The addition amount of the setting retarder was changed to four levels based on the total weight of the solidified material. (4) Table 4 shows the relationship between the age and the compressive strength when the mixed milk, solidified material milk and soil mixed milk were sealed and cured in a 20 ° C constant temperature curing room.

[0039]

[Table 4]

Table 4 shows that among the compositions described in claim 1, Portland cement had a fineness Blaine value of 32.
The test results at 70 cm ² / g are shown. When the weight ratio of Portland cement exceeds 30%, the strength of the mixed milk is already developed at one day of age even if the strength of the mixed milk is delayed by increasing the amount of the setting retarder added. ing. Therefore, unless the weight part of Portland cement is not more than 30%, it can be said that a predetermined setting delay effect cannot be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masahiro Yoshihara 1 Sumitomo Osaka Cement Co., Ltd., 1 Kanda-Midshiro-cho, Chiyoda-ku, Tokyo (56) References JP-A-61-211394 (JP, A) JP-A-61-211394 Hei 9-100471 (JP, A) JP-A Hei 7-138566 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09K 17/02 C09K 17/06 C09K 17/10 C09K 17 / 12

Claims (4)

(57) [Claims] If the mixing of the soil and the soil conditioner is not uniform, 50 to 99 parts by weight of blast furnace slag powder and 0 to 20 parts by weight of gypsum powder, and 1350 to 5000 cm ² / g of powder When preparing a solidified material milk by dispersing a solidified material containing 1 to 30 parts by weight of Portland cement having a degree of Brain value in water, the solidified material milk is added to the solidified material in an amount of 0.1 to
5.0% of organic acid salt, organic acid, polymer complex, organic substance
Derivatives, sugars, silicates, borates, and phosphates
A soil improvement method characterized by further comprising a setting retarder comprising at least one selected from the group consisting of: mixing the mixed milk with soil and solidifying the mixed milk. 2. When the mixing of the soil and the soil conditioner is not uniform, 50 to 98 parts by weight of blast furnace slag powder and 0 to 20 parts by weight of gypsum powder and 1350 to 5000 cm ² / g fineness When preparing a solidified milk by dispersing a solidified material containing 1 to 20 parts by weight of Portland cement having a Blaine value and 1 to 10 parts by weight of fine powder of cement hydrate in water, the solidified material milk , 0.1 to the weight of the solidified material
A soil improvement method, further comprising adding about 5.0% of a setting retarder, mixing the mixed milk into soil, and solidifying the mixed milk. 3. When the mixing of the soil and the soil conditioner is not uniform, 70 to 99 parts by weight of blast furnace slag powder and 0 to 20 parts by weight of gypsum powder, and 1 to 10 parts by weight of cement hydration When preparing a solidified milk by dispersing a solidified material containing fine particles of the product in water, the solidified material milk is added to the solidified material in an amount of 0.1% by weight of the solidified material.
A soil improvement method, further comprising adding about 5.0% of a setting retarder, mixing the mixed milk with soil and solidifying the mixed milk. 4. The method of claim 1, wherein the setting retarder is an organic acid salt, an organic acid,
The ground improvement method according to claim 2 or 3, comprising at least one selected from a polymer complex, an organic derivative, a saccharide, and an inorganic salt.