JP3336058B2 - Ground injection agent and its injection 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 liquid for ground injection using a hydraulic mixed fine powder mainly composed of blast furnace slag, silica sol (aqueous colloidal silica) and an auxiliary agent as a main material, and having a permeability. The present invention relates to a ground injection agent which is very excellent and is used for strengthening sandy ground and soft ground, and a method of injecting the same.

[0002]

2. Description of the Related Art Conventionally, as a ground injecting agent, a material mainly containing water glass is often used, and its hardening agent (gelling agent) includes calcium salts such as portland cement, slaked lime, steel slag, and sodium hydrogen sulfate. , Magnesium sulfate,
Various acids such as phosphoric acid, organic acids such as glyoxal and ethylene carbonate, and esters have been used. There have also been proposed some ground injection agents containing silica sol as a main component, which dislikes the alkali of water glass.

For example, slaked lime or cement is added to silica sol.
(JP-A-57-164186, JP-A-59-66482),
Alkaline earth metal salts such as magnesium sulfamate
(JP-A-63-168485), alkali metal salts such as sodium chloride and sodium hydrogensulfate (JP-A-59-152985), and trivalent metal salts such as aluminum salts (JP-A-59-152985).
No. 84), and a method of curing by adding an electrolyte.

A method of accelerating the hardening of cement by adding zeolite to cement is described in JP-A-2-8981.

[0005] Further, gel time regulators for cement have already been introduced in many documents, and alkali metal carbonates, alkali metal phosphates and alkali metal carboxylate salts have been put to practical use.

[0006]

The method using water glass has a problem in durability due to the presence of a large amount of sodium salt contained in the injected material, as already introduced in many documents. Only the value as a temporary material is recognized.

[0007] In addition, contamination of groundwater and corrosion of underground buried objects become problems due to the salts eluted. These disadvantages are exactly the same when acid water glass is used.

Accordingly, attention has been paid to the use of silica sol containing substantially no alkali metal salt or no alkali metal salt. However, metal salts as an electrolyte make the silica sol gel and convert it into a non-fluid solid. However, the gel strength is usually 1 kg / cm ² or less, and since this gel does not increase in strength over time, it cannot be expected to have durability against running water or ground fluctuation.

[0009] A ground injection comprising two components, a cement material having a proven durability and a silica sol substantially containing no harmful substance to cement, is expected as a durable injection.

[0010] However, a ground filler made of cement and silica sol is effective in strengthening the ground by filling the cavities. However, it prevents the liquefaction of the sand ground caused by an earthquake and improves the ground affected by seawater. It is not effective as a ground injection agent.

The reason for this is that ordinary cement particles have
This is probably due to poor permeability to fine gaps in the sand layer due to 40 μm.

Therefore, in particular, even when a slurry of finely divided cement particles is used, the reaction with the silica sol is quick, and a gel having no strength is generated, and the permeation and injection into the sand layer is not performed, and the injection is possible. If at all, it is hardly applicable when there is a flow of groundwater.

[0013] In addition, in the conventional suspension-type injection agent using silica sol, particularly in the ground affected by seawater, Mg ²⁺ and Ca ²⁺ in the sea water cause coagulation of the silica sol. Because of the action, a gel which does not exhibit strength as described above is produced, and the ground improvement which can hardly be practically used is made.

In view of the above facts, the present inventors have conducted intensive studies and found that the above problem can be solved by using a specific blast furnace slag-containing fine powder and an auxiliary agent for silica sol. Thus, the present invention has been completed.

That is, an object of the present invention is to provide a non-polluting and durable ground injection agent capable of improving the ground with excellent hardening ability and permeability to not only ordinary ground but also sand layers or soft ground immersed in seawater, and the like. It is to provide an injection method.

[0016]

That is, the ground injection agent provided by the present invention is a blast furnace slag powder of 50 to 90 weights.
Parts and Portland cement clinker powder 10-5
0 parts by weight of the mixed powder having a Blaine specific surface area of 70
It is characterized in that the basic component is a slurry of a hydraulically-mixed fine powder within a range of from 00 to 8500 cm ² / g , a silica sol, and a mixture of an alkali metal carbonate and a soluble phosphorus compound as an auxiliary agent. .

Hereinafter, the present invention will be described in detail. The present invention is a suspension type ground injection agent based on three components as described above. First, as the silica sol to be used, an ion exchange method using water glass as a raw material, a deflocculation method, an acid neutralization method, one produced by an electrodialysis method, etc., as an example of the production method, U.S. Patent No. 2,577,484 Description, U.S. Patent No. 3,711,419
No., U.S. Pat.No.2,572,578, JP-A-52-3
No. 3899, U.S. Pat.No. 3,668,088,
No. 317115 and the like.

In addition, for example, the production method by oxidation of metallic silicon described in US Pat. No. 3,650,977 and Japanese Patent Publication No. 46-7367, US Pat. No. 2,951,044 and JP
Silica sol according to the production method of fine silica powder by water dispersion described in JP-A-2-127216 can also be used.

As the silica sol, those having a large particle diameter have low gel strength, and in many cases, those having an average particle diameter of 3 to 100 nm can be practically used.
m or less, usually 10 to 20 nm is practically preferable.
Particularly, silica sol of small particle grade of 3 to 10 nm has high sol strength and is particularly preferable. It should be noted that silica sol of a grade having an average particle diameter of less than 3 nm has a large content of an alkali stabilizer like water glass, and is hardly suitable for the purpose of the present invention.

The silica sol usually contains a small amount of alkali ion (or hydrogen ion) for stabilizing the colloid. The alkali content of the silica sol used in the present invention is SiO ₂ / M ₂ O (M Represents an alkali metal) in a molar ratio of 5 to 500.

In the present invention, it is important to use a slurry of hydraulically mixed fine powder mainly composed of blast furnace slag as a suspension for the silica sol.

In the present invention, such a hydraulic mixed fine powder refers to a fine powder obtained by blending Portland cement clinker with blast furnace slag in an appropriate amount as an aid (hereinafter referred to as “mixed blast furnace slag powder”).

Here, the blast furnace slag powder is a quenched blast furnace slag and has a vitrification ratio of 9 from the viewpoint of the strength of the ground injection agent.
0% or more and a basicity of 1.6 or more are preferable. Portland cement clinker refers to clinker usually obtained as a portland cement precursor, and does not mean portland cement obtained by mixing gypsum with this .

Such mixed blast-furnace slag powder is prepared by selecting the raw materials and setting an acceptable range of the following mixing ratio, and depending on the properties of the ground, the permeability of the injection agent, the stability of the gel time, and the strength development. In view of this, there is a degree of freedom in use conditions, and the reliability is extremely high in terms of practicality.

The mixing ratio of the mixed blast furnace slag powder can vary depending on the properties of the ground, but in many cases, 50 to 90 parts by weight of the blast furnace slag powder and the rest, ie, 10 to 50 parts by weight, are Portland cement clinker. In particular,
A blending composition of 75 to 90 parts by weight of blast furnace slag powder and 10 to 25 parts by weight of Portland cement clinker is preferred.

By increasing the amount of the blast furnace slag powder, the influence of Portland cement clinker is reduced.
The dispersibility of milk and the permeability of the ground injection agent are improved without being affected by the properties of the ground.

The mixed blast furnace slag powder must have a fineness at least finer than that of general cement particles. In particular, the blast furnace slag powder has a fineness based on a Blaine specific surface area of 7000 to 8500 cm ² / g. Ultrafine powders in the range are preferred.

When the specific surface area of the blended blast furnace slag powder is increased, the particle diameter becomes relatively small, and the permeability to the sand layer and the strength of the ground injection agent are improved in combination with the action of the auxiliary agent described below. . When the fineness is less than 7000 cm ² / g, good permeability cannot be obtained, or when the gel time is prolonged, material separation of the ground injection agent tends to occur.

On the contrary, the Blaine specific surface area is 8500 cm ²
/ G, the viscosity of milk is high, the activity of Portland cement clinker powder becomes strong, and coagulation between particles is promoted, so that not only the effect of improving permeability but also the stability of gel time can be obtained. Chip. In addition, the crushing ability becomes industrially difficult.

The powder of a preferred embodiment of such mixed blast furnace slag powder is different from blast furnace cement which is a mixture of portland cement and blast furnace slag, and has a composition which is not in the ordinary cement JIS standard. Because of its properties, when it is used for silica sol as a slurry, it can be expected to have better seawater resistance and long-term strength enhancement than that of ordinary cement slurry type, so it can prevent liquefaction of sandy ground near the coast. It is suitable.

Another important feature of the present invention is that the silica sol-mixed blast furnace slag powder system contains an appropriate amount of a mixture of an alkali metal carbonate and a soluble phosphorus compound as an auxiliary as described above.

The alkali metal carbonate includes sodium and / or potassium carbonate, bicarbonate, sesquicarbonate and the like. The soluble phosphorus compound includes, for example, phosphoric acid, sodium and / or potassium 1
Phosphates, secondary phosphates, orthophosphates, pyrophosphates,
Tripolyphosphate and the like may be mentioned, and they may be used alone or in combination of two or more. Of these, a weakly acidic mixture is particularly preferred.

In the above assistants, the mixing ratio of the alkali metal carbonate and the soluble phosphorus compound is not uniform due to the properties of the ground and the influence of seawater, but in many cases, the molar ratio (PO ₄ ³⁻ /
CO ₃ ^2- ) is in the range of 0.05 to 1.

The ground injection agent according to the present invention comprises the above-mentioned components. If necessary, a known cement dispersant or an inorganic fine powder such as synthetic silica or synthetic zeolite having an average particle diameter of 1 μm or less may be used. May be blended.
Further, a chelating agent such as a carboxylic acid such as citric acid, tartaric acid, and gluconic acid or an alkali metal salt thereof may be contained. In particular, it is preferable to mix inorganic fine powder because the range of application is expanded to further improve the gel strength of the ground injection agent.

The use ratio of the basic component in the ground injection agent according to the present invention should be appropriately set according to the properties of the ground. In many cases, silica sol (in terms of SiO ₂ ): mixed blast furnace slag powder: auxiliary Weight ratio of 1: 1 to 10: 0.05
Is a practical range, and in particular, 1: 2 to 6: 0.1.
A range of 1 is preferred.

The injection method of the present invention using the above ground injection agent is a one-shot system in which a slurry comprising a mixture of a silica sol, a mixed blast furnace slag powder and an auxiliary agent is appropriately mixed and pressure-injected in a one-liquid one-system system. The injection is performed in one of a 1.5-shot system in which injection is performed in a two-liquid system and a two-shot system in which injection is performed in a two-liquid system. Particularly preferred is a method in which a slurry of mixed blast furnace slag powder, a mixed solution of silica sol and an auxiliary agent is pressure-injected into the ground by a one-shot method or a 1.5-shot method. Although the injection pressure varies depending on the properties of the ground, in many cases, the injection pressure is 0.1 to 1.0 kg.
/ Cm ² .

[0037]

The details of the mechanism of the hardening reaction of the ground injection agent according to the present invention are not clear, but it is presumed to be as follows. That is, the silica sol develops initial strength by Ca ²⁺ or Mg ²⁺ released from the mixed blast furnace slag powder by hardening based on the gelation reaction of the silica sol, and then increases its strength by the hydration reaction of the mixed blast furnace slag powder. It is expected to increase gradually and maintain long-term strength.

The soil injection agent according to the present invention effectively enables such a hardening reaction even in a sand layer or seawater immersed ground, and improves hardening of soft ground. The effect due to the synergistic action between the physical properties and the auxiliaries is great.

One of them is mainly blast furnace slag powder,
In addition, by setting the powder as fine as possible, preferably a fineness of 7000 to 8500 cm ² / g, the hardening effect after injection and permeation is sufficiently exhibited even in the gap between sand layers.

Another is that the presence of the auxiliary agent causes the above-mentioned hardening reaction to take place mainly even in the ground affected by seawater. Although the detailed mechanism of the reason is unknown, it is possible to presume the following. In general, a suspension type ground injection agent using silica sol for ground immersed in seawater or the like has almost no practicality, but this is because Mg ²⁺ or Ca ²⁺ already existing in ground water is from suspended particles. This is probably because these cations react more quickly than these eluted cations to form a gel and inhibit the reaction with the particles.

[0041] Thus, the elution from the suspended particles by trapping the said aid is present the Mg ²⁺ and Ca ²⁺ already present as CO ₃ ^2- and PO ₄ ^3- promptly react to an insoluble salt Cations, which can cause a hardening phenomenon. Furthermore, the curing reaction can be controlled widely by the buffering action of the auxiliary agent, so that the gel time of the injection can be arbitrarily set within a practical range.

[0042]

The present invention will now be described more specifically with reference to examples and comparative examples. Examples 1 to 5 and Comparative Examples 1 to 8 Using blast furnace slag (vitrification rate = 98%, basicity = 1.88: manufactured by Nippon Steel Muroran Works) and ordinary Portland cement clinker (manufactured by Nittetsu Cement) The blast furnace slag mixing ratio was 80 parts by weight, and the specific surface area of the brane was 8400 cm.
^{A 2} / g mixed blast furnace slag powder was trial manufactured. A ground injection agent under the following conditions was prepared using the mixed blast furnace slag powder and silica sol (Silica Doll 30: manufactured by Nippon Chemical), and a penetration test into a sand layer and a sand gel strength test were performed by the following injection method and evaluation method. .

(1) Injection method A 10 cm long Toyoura standard sand having a porosity n = 43.8% and a water permeability of 2.3 × 10 ^-2 cm / sec was previously placed under an acrylic pipe of φ5 × 30 cm. (0.3-0.1 mm) layer was made and soaked in seawater. After stirring the milk for the required time,
The same amount of the silica sol solution was added and stirred for 10 seconds, and a ground injection agent was allowed to flow from the upper portion of the acrylic pipe to allow natural permeation.

(2) Evaluation method (2.1) Gel time If the ground injection agent mixed with the components is put into a beaker and stirring is continued with a magnetic stirrer, the viscosity gradually increases.
At this time, the gel time is measured as the time from when the ground injection agent is put into the beaker, until the viscosity increases, the gel is eventually formed, and the fluidity disappears even when the beaker is tilted by 90 degrees and the flow does not flow down.

(2.2) Compressive strength The compressive strength of the sand gel was set to a condition that a penetration length of 10 cm was obtained, the mold was removed after 24 hours, cured in water (20 ° C.), and a specimen of φ5 × 10 cm was arm-slurred. Using a mold strength tester, the uniaxial compressive strength was measured in the age of 7 days.

[0046]

[Table 1]

Table 1 shows the results of this example and the comparative example. As can be seen from the above results, when sodium carbonate was used alone as an auxiliary agent or when the amount of monopotassium phosphate was not more than a certain amount, it was not possible to penetrate into the sand layer because it coagulated simultaneously with contact with seawater. On the other hand, when the amount of mono-potassium phosphate is a certain amount or more, it can be penetrated into the seawater immersion layer, but the cured product may have low compressive strength or may not be cured. In order to penetrate the seawater immersion layer and obtain practical strength, it is most effective to use an appropriate amount of a mixture such as sodium hydrogen carbonate and monopotassium phosphate.

Comparative Examples 9 to 10 and Examples 6 to 7 A mixture consisting of silica sol (SiO ₂ : 30% by weight, pH 9.8, average particle diameter: 13 nm), an auxiliary agent (liquid A), and a mixed blast furnace slag powder. Various ground injection agents were prepared from the solution B at the composition ratios shown in Table 2. Standard sand obtained by mixing solution A and solution B with various types of obtained ground injection agent and immersing fresh water or seawater
(Toyoura) was injected with 0.25 kg / cm ² injection pressure to prepare a cured specimen, and the gel time and compressive strength were measured at that time. Was done.

[0049]

[Table 2]

As can be seen from the above results, when sodium bicarbonate is used alone as an auxiliary, there is no problem in penetration into the freshwater immersion layer, but it cannot penetrate into the seawater immersion layer. All injections gave good results.

Examples 8 to 11 The ground injecting agent obtained by blending the same silica sol, mixed blast furnace slag powder and auxiliary as used in Examples 6 and 7 was divided into Liquid A and Liquid B and was similarly treated with seawater. Standard sand soaked
(Toyoura) was injected at an injection pressure of 0.4 kg / cm ² to prepare a cured product, and the gel time and compressive strength at that time were measured to evaluate the performance of the ground injection agent. Obtained.

[0052]

[Table 3]

From the above results, by using an appropriate amount of a mixture of sodium bicarbonate and monopotassium phosphate as an auxiliary agent, the gel time should be 1 minute or less and be a ground injection agent that can be injected into a sand layer immersed in seawater. I understood.

Examples 12 to 14 The same ground sol obtained by mixing the same silica sol, mixed blast furnace slag powder and auxiliaries as used in Examples 8 to 11 was injected into a sand layer immersed in seawater by the one-shot method. When a cured product was prepared and the gel time and compressive strength at that time were measured to evaluate the performance of the ground injection agent, the results in Table 4 were obtained.

[0055]

[Table 4]

As can be seen from the above results, by using an appropriate amount of a mixture of sodium hydrogen carbonate and monopotassium phosphate as an auxiliary agent, the gel time can be about 1 hour, and the gel time can be injected into a sand layer immersed in seawater. Was.

Examples 15 to 17 and Comparative Examples 11 to 15 The ground pouring agent obtained by blending the same silica sol and mixed blast furnace slag powder as used in Examples 12 to 14 with the auxiliaries shown in Table 5 below: Example 1 divided into solution A and solution B
In the same manner as in Nos. 1 to 5, a ground injection agent was poured into standard sand (from Toyoura) immersed in seawater to allow natural permeation, and a penetration test into the sand layer and a sand gel strength test were performed. Table 5 shows the results.

[0058]

[Table 5]

Example 18 The ground injection agent of Example 6 was injected into a sand layer immersed in seawater by the following 1.5 shot method. 8.35 × permeability
A plunger type pump (trade name: Dabcon Pump, DP) is applied to a sand layer having a density of 10 ⁻³ cm / sec and a porosity of 42.5%.
O4 type, Shimazaki Seisakusho) using an injection pressure of 0.5 kg / cm ²
At 24 liters. At the injection stage, there was no problem, and it was possible to infiltrate the sand layer soaked with seawater. Seven days after the injection, the modified sand layer had a water permeability of 3.5 × 10 ⁻⁷ cm / sec and a compressive strength (sand gel) of 14.5 kg / cm ² . From these results, it was confirmed that the ground injection agent of the present invention sufficiently satisfies the performance in practical use.

[0060]

Industrial Applicability The ground injection agent and the injection method using the same according to the present invention can be widely applied to the improvement of soft ground not only for general ground but also for sand layers or seawater immersed ground. . Further, the applicability is wide in terms of the gel time of the ground injection agent. On the other hand, since the ground injection agent according to the present invention mainly uses silica sol and blast furnace slag, alkali pollution caused by water glass and cement as in the prior art is significantly reduced, and it can be handled safely. It can be expected as a highly practical soil injection agent even in deep civil engineering work.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09K 17/10 C09K 17/10 P (72) Inventor Akira Sekine 9-15-1, Kameido, Koto-ku, Tokyo Japan Chemical Industry Co., Ltd. Research and Development Division (72) Inventor Seiichi Shimobayashi 64 Nakamachi, Muroran, Hokkaido Nippon Steel Cement Co., Ltd. (72) Inventor Eiji Miyoshi 9-15-1, Kameido, Koto-ku, Tokyo Japan Chemical Industry Co., Ltd. Research and Development Division (72) Inventor Keiichi Karatsu 64 Nakamachi, Muroran, Hokkaido Nippon Steel Cement Co., Ltd. Research and Development Department (56) References JP-A-5-140557 (JP, A) (58) Fields surveyed (Int. Cl ^7, DB name) C04B 28/08 C04B 22/06 C04B 22/10 C04B 22/16 C09K 17/00 -. 17/52

Claims (3)

(57) [Claims] 1. A blast furnace slag powder of 50 to 90 parts by weight and
10-50 parts by weight of landland cement clinker powder
A mixed powder having a Blaine specific surface area of 7000 to 85
00cm 2 / ^g hydraulic mixing fine powder of the slide <br/> Lee is in the range of, silica sol and ground infusion, characterized in that the basic component of the mixture of alkali metal carbonates and soluble phosphorus compound as an aid . 2. Silica sol (in terms of SiO ₂ ): hydraulic mixed fine powder: auxiliary in a weight ratio of 1: 1 to 10: 0.05 to 1
Ground infusate according to claim 1 having the composition ratio. 3. The method for injecting a ground injection agent according to claim 1 or 2, wherein a slurry of the hydraulically mixed fine powder and a mixed solution of silica sol and an auxiliary are subjected to a one-shot method or a method of 1.
A method of injecting a ground injection agent, which is injected into the ground by a 5-shot method.