JP2001098271A - Ground solidification material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension-type ground solidification material which is based on a neutral silica sol and fine cement particles, has a prolonged allowable time for permeation and hence is excellent in permeation properties, has high solidification strengths, and hardly exhibits alkali leaching. SOLUTION: This ground solidification material mainly comprises fine cement particles and a neutral silica sol prepared by removing the most part of an alkali of water glass with an ion-exchange resin. The thickening time of the material is prolonged by using a specified amount of the neutral silica sol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension type soil compaction material of a neutral silica sol / fine particle cement system, and more particularly to a soil compaction material having a long permeation time, excellent permeability, and exhibiting high compaction strength. Regarding binder.

[0002]

2. Description of the Related Art Conventionally, various grouts have been known as grouts for injecting ground into a ground. For example,
A slag grout using water glass having a small molar ratio and high alkalinity is known. Although this grout has a high consolidation strength, there is concern about leaching of alkali. A solution type grout in which a polyvalent metal salt is added to a neutral silica sol is also known, but this has a drawback that the compaction strength is small. In order to solve this strength, a method has recently been known in which neutral silica sol and Portland cement are combined at 1.5 shots and injected, but the gelation time of this grout is as short as 1 minute at most, and the permeability is low. It is inferior to.
Further, a grout obtained by adding blast furnace slag and Portland cement to neutral silica sol is also known. However, the grout using such a neutral silica sol is not only short of the gelation time measured by the cup inverted method on the ground as less than 10 minutes, but also the gelation time is further shortened in the soil, so that the penetration is poor, Clogging occurs between soil particles. Further, as a ground consolidation material using a material that cannot be gelled, a cement / bentonite suspension, a slag-alkali stimulant (excluding water glass) suspension and the like are known. However, none of them can increase the viscosity of the blended liquid in a short time, and it has been considered that limited injection is difficult. When a small amount of water glass is mixed with a cement suspension, the mixture becomes a thixotropic suspension in about 10 seconds. Therefore, such a mixed solution is sometimes used as a backing material. Is completely different from the liquid mixture of the above.

[0003]

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, the present inventors have found that a specific neutral silica sol, fine particle cement, and, if necessary, slag are blended under desired conditions. Although the compounded liquid gradually increases in viscosity and keeps a plastic state, it is possible to eliminate a definite gelation time. Such a blended liquid is easy to adjust the thickening time and can extend the permeation time, so that it has good permeability, and after the injection is completed, loses fluidity and substantially solidifies, and the gel is gelled. It has been discovered that the same effect as a grout exhibiting an aging time can be obtained, and the present invention has been completed. The object of the present invention is that the permeation time is long, the permeability is excellent, and high consolidation strength is exhibited, and there is little alkali leaching, so that the consolidation is not only excellent in durability but also has little effect on the environment. It is another object of the present invention to provide a neutral silica sol / particulate cement type suspension-type ground consolidating material in which the disadvantages of the above-mentioned known technology are improved.

[0004]

In order to achieve the above-mentioned object, the ground consolidating material of the present invention is obtained by removing most of the alkali of water glass with an ion exchange resin and granulating the neutralized water. Silica sol, fine particle cement and slag used as necessary are used as active ingredients, and the content of the neutral silica sol is 0.5 to 5% by volume (SiO ₂ concentration 30%
In terms of silica sol).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The ground consolidated material according to the present invention gradually thickens after being blended,
As the viscosity increases, the plastic state is maintained, but no gelation occurs. Here, the thickening time is 1 minute or more, preferably 10 to
About 120 minutes is appropriate, and thereafter the plastic state is maintained for 10 minutes or more, preferably 30 minutes or more. When such a mixed solution according to the present invention is injected into the ground, when the ground is dense, the same effect as in the conventional gelation is exerted at the thickening stage, the mixed solution does not penetrate, and the ground is rough. In this case, the injection (penetration) is continued even in the plastic state from the thickening stage. Here, in the conventional ground consolidation material, the gelation time is measured by the cup inversion method, and the time at which the cup does not flow even when the cup is tilted is referred to as `` gelation time '', whereas the compounded liquid of the present invention is Approximately 500 cps (centipoise) when measured with a B-type viscometer
As described above, the viscosity is about 1,000 cps or less, and it does not flow out of the cup even when measured by the cup inversion method. The elapsed time up to this point is referred to as “thickening time”. There are some problems in measuring the suspension with a B-type viscometer, but the conventional gel-forming type ground consolidating material has a viscosity of the compounded liquid measured with a B-type viscometer.
When the viscosity starts to increase, the viscosity rapidly increases to 2,000 cps or more and gels. Therefore, in the present invention, a value measured by a B-type viscometer was used as one standard. Also, as mentioned above,
"Gelling" means that the liquid compound liquid has a shape-retaining property due to the reaction.Specifically, it is measured by the cup inversion method as described above, and it does not flow even if the cup is tilted. State. Such a mixed solution does not penetrate at all when it gels, and maintains a plastic state,
This is completely different from the formulation of the present invention which does not gel.
It should be noted that even if the composition is not gelled by the cup inversion method, it is gradually solidified (or solidified) after being poured into the soil if no external force is applied between the soil particles. Does not fall under. In addition, when the thickening time is 10 minutes or more, almost the plastic state continues for 10 minutes or more.

[0006] The "plastic state" refers to a state in which fluidity is exhibited when an external force due to injection or the like is applied, but is not exhibited when the external force is removed. Since such a plasticized state at the time of compounding deteriorates permeability, such a case is excluded from the scope of the present invention, and it is necessary that the plasticized state be obtained after at least one minute has passed. If the duration of the plastic state is short, the plastic state may last at least 10 minutes or more, preferably 60 minutes or more, since gelling may occur thereafter. However, the object of the present invention is still achieved.

The present invention described above relates to a ground consolidation material using a neutral silica sol in combination with a fine particle cement, preferably a fine particle slag, wherein the amount of the neutral silica sol used is an amount necessary to thicken the blended liquid, that is, 0.5 to 5% by volume of the total blended liquid, and the fine particle cement preferably has a Blaine specific surface area of 4,000 cm ² / g or more, and if necessary, a thickening time modifier is added. You can also. To explain further, there is no problem when the blended liquid does not gel, but when it is apparently in a gel state, its strength is measured before the solidification of the cement starts and 0.1 kgf / cm ²
If it is below, it is a weak gel which is almost broken by stirring, and such a composition is within the scope of the present invention. That is, the blending amount of the neutral silica sol is such that the blending solution thickens but an elastic gel such as a homogel of a water glass solution type grout cannot be formed, and the particle size of the fine particle cement and the fine particle slag are used in combination. Furthermore, it depends on the amount of the thickening time regulator added.

[0008] The infiltration time is not clear because it depends on the condition of the ground. However, in a conventional silica sol-cement grout using a general neutral silica sol, a gel time adjustment agent is added. Also, the gel time is about 10 minutes or less (especially 3 minutes or less in summer, and extremely short as 10 seconds or less when using ultrafine cement for cement, and it is almost impossible to lengthen this). Not only is it extremely short, but gelation occurs rapidly after the start of thickening, and the gel strength is high after gelation, so that the gel cannot be further broken and penetrated.

On the other hand, the ground consolidation material according to the present invention can have a thickening time of 1 hour or more, and has a so-called gel strength. No) can be penetrated depending on the ground even after the elapse of the thickening time, and thus the permeation possible time can be sufficiently lengthened.

When the cement is injected as a single suspension, the cement is clogged or settles. On the other hand, in the ground consolidating material of the present invention, the silica in the neutral silica sol adheres to the cement particles. In order to improve the lubricity of the cement particles (pass through the gaps of the sand without clogging), the cement particles have good permeability, and the subsequent thickening hardens almost the entire injection liquid.

The neutral silica sol used in the present invention is prepared by treating water glass with an ion-exchange resin to substantially separate and remove alkali such as Na ⁺ ions, and heat granulating to a particle size of 6 to 50 mm. The translucent liquid obtained above is neutral to weakly alkaline, preferably weakly alkaline having a pH of 8.0 to 10.5, has a specific gravity of 1.16 to 1.24, and has a SiO _{2 of} approximately 10 to 10. 40 wt%, Na ₂ O is 0.01
It is in the range of 4% by weight. 4% by weight of Na ₂ O
When the above is reached, the silicate colloid dissolves and becomes an aqueous solution of silicate. On the other hand, when the content of Na ₂ O is 0.01% by weight or less, the silicate colloid cannot exist stably and aggregates. That is, when Na ₂ O is in the range of 0.01 to 4% by weight,
The ions can be distributed on the surface of the silicate colloid to maintain a stable colloidal state. In this case, the particle size of the silicate colloid is mainly about 6 to 50 mm. When the particle size of the silicate colloid becomes 50 millimicrons or more, it precipitates. The above silicic acid colloid has a molar ratio (SiO ₂ / Na ₂ O) of about 10 to 1,000, and a pH of 8 to 10 is desirable for the stability of the colloid. The silicate colloid prepared in this manner is semi-permanently stable, and there is no concern that the silicate colloid will be gelled when it is transported from the factory to the site and when it is injected.

The fine particle cement used in the present invention preferably has a Blaine specific surface area of 4,000 cm ² / g or more from the viewpoint of permeability. When the thickening time is made longer, the amount of the fine particle cement is particularly reduced. Further, when the amount of the neutral silica sol used is relatively large and gelation is likely to occur, a fine particle slag may be used in combination in order to make the mixture not gelled. The Blaine specific surface area of the fine particle slag used in combination is 8,000 cm ² / g or more, preferably 10,000 c ² / g.
m ² / g or more. The strength of the solidified material can be appropriately selected according to the application, but the amount of the fine particle cement used is preferably 30 to 300 g per 1,000 ml of the ground solidified material. In particular, in order to obtain a high-strength and durable compact, the amount of the fine-particle cement is preferably 50 g or more per 1,000 ml of the ground consolidating material, and the fine-particle slag is preferably used in combination. In this case, the ratio of the fine particle cement and the fine particle slag is 100 to
It is preferably used at 20: 0 to 80.

[0013] Conventionally, when only suspension-type consolidation material is injected, excavation cannot often be performed under groundwater due to spring water, and water is stopped using a solution-type injection material in combination. . However, since the ground consolidation material of the present invention has good permeability and low permeability of the consolidation material, even when injected alone, there is no spring water trouble and excavation can be performed.

In the neutral silica sol / fine particle cement system according to the present invention, the thickening time can be adjusted by changing the amount of the neutral silica sol and fine particle cement. In addition to delaying the thickening time by adding the compound, the permeability can be improved by lowering the viscosity of the blended liquid. In the case where gelation occurs in a short time, a thickening time adjusting agent is added to increase the viscosity but not to gel.

The amount of the thickening time adjusting agent can be appropriately selected depending on the use conditions of the ground injection material, particularly the liquid temperature, but the thickening time can be 30 minutes or more, and if necessary, several hours. It is a feature of the present invention, in such a case, the thickening time regulator is added to the fine particle cement 0.1 to 10
% By weight. Examples of the thickening time regulator include alkali metal bicarbonates, carbonates, phosphates, acid phosphates, pyrophosphates, citric acid, tartaric acid and sodium ligninsulfonate and sodium polysulfonate (delayed type). And cement fluidizing agents. Among these, particularly preferred modifiers are alkali metal bicarbonates, carbonates, and the like, which have little effect on the strength of the consolidated product. When such a thickening time modifier is added to the neutral silica sol side and mixed with the suspension of fine cement at the time of injection, aggregates of the cement cannot be formed, and the particle size of the particles in the suspension is small. Also, since the viscosity of the liquid is small, the permeability is better.

The active silica obtained by dealkalizing water glass with an ion exchange resin gels only by mixing it with sodium bicarbonate. Even if the suspension is mixed, it does not become in a plastic state as in the case of using the neutral silica sol of the present invention.

When a cement fluidizer is added, it is preferable to add it to the fine particle cement side, and in that case, it is preferable to add another modifier to the neutral silica sol side. When adding a regulator, a method of dissolving in advance in water and then adding a neutral silica sol is preferable, and it is preferable to select and use a regulator which is uniform in that state.
Further, by adding a thickening time regulator, A, B
The viscosity at the time of mixing the two liquids is reduced, and the permeability can be further increased.

A specific method for preparing the liquid mixture of the present invention will be described in more detail. First, the specific surface area of cement and slag and the amount used thereof are determined from the strength of the solidified material. Then, the used amount of the neutral silica sol is adjusted so that the silica concentration is 0.5 to 5% by volume.
So that If the mixed solution gels even in this range of the neutral silica sol, a thickening time regulator is added.

When the ground consolidation material of the present invention is injected, a solution type or suspension type injection material having a short gelation time is injected as a primary injection material to prevent leakage to the ground or to fill a rough portion. Then, after the escape of the consolidated material of the present invention is prevented, the ground consolidated material of the present invention may be injected.

Further, the ground consolidation material of the present invention has a low viscosity and a good permeability, so that when the double pipe double packer method of ensuring a packer effect is adopted, the injection speed is increased.
The construction efficiency can be improved, and on the other hand, there is a large number of injection holes to be injected at once, and a method using an injection pipe that spreads over a wide area above and below the injection pipe (here, the porous injection method) is used. In addition, the injection speed can be reduced so that the infiltration can be performed without raising the ground.

[0021]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but these examples are merely examples of the present invention, and the present invention is not limited to these examples. First,
Neutral silica sol used in Examples and Comparative Examples of the present invention,
The slag, cement and thickening time regulator are summarized below. (1) Neutral silica sol A neutral silica sol having the composition shown in Table 1 obtained by treating water glass with an ion-exchange resin to remove most of the alkali and granulating it (manufactured by Asahi Denka Kogyo KK) )It was used.

[0022]

[Table 1]

(2) Slag Three kinds of slags having different compositions and pulverization degrees shown in Table 2 were used.

[0024]

[Table 2]

(3) Cement Portland cement and blast furnace cement having different compositions and pulverization degrees shown in Table 3 were used.

[0026]

[Table 3]

(4) Thickening time regulator Sodium bicarbonate (reagent first grade: NaHCO ₃ ) was used as a typical thickening time regulator.

Examples 1 to 9 and Comparative Examples 1 to 6 The neutral silica sol, sodium bicarbonate and water in Table 1 were used as the liquid A, and the slag shown in Table 2 and the aqueous suspension of the cement shown in Table 3 were used as the liquid B. , A liquid and B liquid were mixed at the ratios shown in Table 4 to prepare various types of ground consolidated materials. The thickening time of the obtained ground consolidation material was measured by a B-type viscometer, and the uniaxial compressive strength was measured in accordance with the Japan Society of Soil Engineering Standard “Uniaxial compression test method for soil”. The compositions of Examples 1 to 9 were all 1 after thickening.
The plastic state continued for 0 minutes or more. Table 4 shows the results.

[0029]

[Table 4]

* 1 After 3 hours, the viscosity hardly increased.

* 2 Even after 3 hours, it did not reach 500 cps.

The thickening time was measured at a liquid temperature of 20 ° C.

Examples 10 to 12 and Comparative Examples 7 and 8 A penetration test was carried out for some of the formulations of the above Examples and Comparative Examples. Table 5 shows the results.

<Infiltration test> A 5φ x 100cm acrylic pipe was filled with Toyoura standard sand so as to have a relative density of about 60%, saturated with water, and then mixed with the above-mentioned typical examples and comparative examples. It was injected at an injection pressure of 1 kgf / cm ² and the permeation distance was measured. The filling of Toyoura standard sand was performed by dividing a predetermined amount into several times, and each time the side of the pipe was hit with a hammer. Further, the preparation of the compounding liquid was carried out by putting both liquids A and B in a mixer and stirring for 10 seconds. The permeation distance was defined as a permeation distance by measuring a range where the color was clearly changed from outside the pipe by visual observation.

[0035]

[Table 5]

* In Comparative Example 7, it is considered that the permeation distance was shortened because the viscosity increased quickly.

Examples 13 to 16 and Comparative Examples 9 and 10 30 ° C. for some formulations of the above Examples and Comparative Examples
Was measured for the thickening time. The amount of the thickening time regulator (sodium bicarbonate) used was added as shown in Table 6, and the other amounts were the same. Table 6 shows the results. From this result, it can be seen that the thickening time is long even at a high temperature, and the resin can be sufficiently penetrated. Except for the comparative example, the plastic state of each of the examples was 30 minutes or more.

[0038]

[Table 6]

The one marked with * is the gel time (by the inverted cup method).

Examples 17 and 18 and Comparative Examples 11 and 12 The gelling time in soil and the thickening time (or gelling time) were measured for some formulations of the above Examples and Comparative Examples.
Table 7 shows the results. <Measurement method for gelation time in soil> A mixing liquid was prepared by stirring and mixing with a mixer for 10 seconds, and 50 g of the mixture was immediately added to 100 g of Toyoura standard sand, mixed and allowed to stand. The bamboo skewer was stabbed there, and the time at which the skewer mark was left when the bamboo skewer was pulled out was measured, and the time was taken as the soil gelation time. At the same time, the thickening time (gelation time in the case of the comparative example) was measured for the remaining mixture.

[0041]

[Table 7]

In the case of the comparative example (marked with *), the gelation time is shown.

[0043]

The present invention is as described above, and a specific amount of neutral silica sol is used as a ground consolidation material containing neutral silica sol and fine particle cement (and fine particle slag as necessary) as active ingredients. Thereby, the following effects are exhibited.

By adding a small amount of neutral silica sol, it is possible to reduce clogging between the soil particles at the time of injecting the fine cement (and the fine slag), so that the permeability to the ground is extremely excellent. Since the injection time can be relatively long, 1
It can also be injected as a liquid formulation. High consolidation strength not found in solution type is obtained. Neutral silica sol does not contain a large amount of a high alkali component unlike ordinary water glass, so that the leaching of alkali has little effect on the environment. Even when a relatively large amount of cement is used, the consolidated silica is durable because the neutral silica sol hardly contains a high alkali component such as ordinary water glass. The calcium component of cement is easily dissolved in water due to alkali, but because it uses neutral silica sol, it reacts with it to become a compound (calcium silicates) that is difficult to dissolve in water. Has good durability. Since the water stopping effect is large, it can achieve its purpose independently even for excavation work. There is no ground uplift due to injection due to good permeability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 17/10 C09K 17/10 P E02D 3/12 101 E02D 3/12 101 // (C04B 28/02 ( C04B 28/02 22:06 22:06 A 22:10 22:10 18:14 18:14 A)) F 103: 44 103: 44 111: 70 111: 70 C09K 103: 00 C09K 103: 00 (72) Inventor Shunsuke Shimada 2-15-10, Hongo, Bunkyo-ku, Tokyo F-term (in reference) 2D040 AA01 AB01 CA01 CA02 CA04 CB03 CC01 4G012 PA29 PB04 PB08 PC08 4H026 CA03 CB02 CB03 CB07

Claims (4)

[Claims] A neutral silica sol obtained by removing most of the alkali of water glass with an ion exchange resin and granulating the water glass,
A ground consolidating material containing fine particle cement and slag used as required as active ingredients, wherein the content of neutral silica sol is 0.5% in the total formulation liquid in terms of silica sol with a SiO ₂ concentration of 30%. Ground consolidation material that is ~ 5% by volume. 2. The ground consolidating material according to claim 1, wherein the amount of the fine cement and the slag used satisfies one of the following requirements (1) and (2). (1) When the fine particle cement is used alone, the compounding amount of the fine particle cement is 30 to 300 per 1,000 ml of the total liquid mixture.
(2) When fine particle cement and slag are used, their weight ratio is fine particle cement: slag = 100 to
20: 0 to 80 3. The soil consolidation material according to claim 1, wherein the fine particle cement has a specific surface area of 4,000 cm ² / g or more. 4. The composition according to claim 1, further comprising a thickening time regulator, wherein the amount of the active ingredient used is within the range satisfying the following (3) and (4), and the compounded liquid alone is in a gel state. The strength at the time of becoming 1 kgf / cm ² or less.
The ground consolidation material described. (3) The amount of particulate cement used is 1,000 ml
(4) The amount of the thickening time modifier used is 0.1 to 10% by weight based on the fine particle cement.