JP2530658B2 - Alkaline hydraulic ground injection material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ground pouring material used for soil stabilization.

[Conventional technology]

Conventionally, fine powder cement has been used as a ground injection material. This fine powder cement is composed of Portland cement and fine powder of granulated slag, and gypsum fine powder is added as necessary.

These ground injection materials are mixed with water at the time of use, pressure-injected to fill the voids in the ground, and are used as curtain grouts for dams or tunnels, or for soil stabilization (JP-A-55-23110). .

[Problems to be solved by the invention]

Conventional ground injection materials do not have sufficient permeation injection into small voids in the ground, and when used in acidic soil or soil with volcanic spring water (water with low pH), they are not durable. However, there was a problem that the effect disappeared within a few years after the injection.

An object of the present invention is to provide a ground injection material which is excellent in injection property and durability and is highly stable in handling to a human body.

[Means for solving problems]

The present invention comprises an alkali hydraulic powder having a particle size of 15μ or less, an alkali metal salt and an alkaline earth metal hydroxide,
Mixing ratio of alkaline hydraulic ground injection material and water is 100-1000
It is an alkaline hydraulic ground injection material characterized in that it is contained in a weight percentage.

The mixing ratio of the alkaline hydraulic ground injection material and water referred to in the present invention means a water / ground injection material ratio.

 Hereinafter, the present invention will be described in detail.

As the alkaline hydraulic powder of the present invention, blast-furnace granulated slag obtained by rapidly cooling slag produced as a byproduct during pig iron production in a blast furnace of an iron mill is used, but other similar compositions obtained by rapidly cooling an alkaline hydraulic substance are all used. It is possible.

The chemical composition of this alkaline hydraulic powder is SiO ₂ , Al.
It is preferable that the main components are ₂ O ₃ and CaO, but there is no harm even if Fe ₂ O ₃ , SO ₃ , Na ₂ O, K ₂ O, MgO or the like is contained.

The finer and more uniform the particle size of this alkaline hydraulic powder is, the more excellent the injection property is, but the particle size is 15 μm or less in consideration of economy. It is preferably 0.5 to 5 μ. If the particle size exceeds 15μ, it becomes difficult to inject into the fine voids in the ground.

In the course of this pulverization, it is preferable to add a pulverization aid as needed. As the grinding aid, triethanolamine, ethylene glycol, water or the like is used.

Alkali substances added to the alkaline hydraulic powder are alkali metal salts and alkaline earth metal hydroxides.

Alkali metal salts include Na ₂ CO ₃ , K ₂ CO ₃ or Li ₂ CO ₃
And alkali metal carbonates such as Na ₂ SO ₄ , K ₂ SO ₄ or Li ₂ SO _{4 and the} like.

As alkaline earth metal hydroxides, Ca (OH) ₂ , Mg
(OH) There are ₂ etc.

These are used as a mixture of one or more alkali metal salts and an alkaline earth metal hydroxide, and those which form an alkali metal hydroxide are preferable.

Among these, the alkali metal salt is preferably alkali metal carbonate such as Na ₂ CO ₃ , K ₂ CO ₃ or LiCO ₃ , and the alkaline earth metal hydroxide is preferably Ca (OH) ₂ .

The particle size is preferably the same as or smaller than that of the alkali hydraulic powder.

As the blending ratio, with respect to 100 parts by weight of the alkali metal salt, preferably 1 to 1000 parts by weight of the alkaline earth metal hydroxide, and particularly 100 parts by weight of the alkali metal salt, 50 to 200 parts of the alkaline earth metal hydroxide. Parts by weight are preferred.

Next, the amount of the mixture of the alkali metal salt and the alkaline earth metal hydroxide to the alkali hydraulic powder is 0.5 to 7
0% by weight is preferable, and 2 to 30% by weight is particularly preferable.

These can be mixed as follows: i) mixing with each other in advance by powder, ii) mixing with each other during use, or iii) as separate aqueous solutions of alkali metal salt and alkaline earth metal hydroxide before use. There is a method of mixing with an alkaline hydraulic powder at the time of use, and any method is acceptable.

In kneading the ground injection material according to the present invention with water,
After kneading with water using an ordinary mortar mixer or a two-stage mixer, pressure is injected by a grout pump.
The mixing ratio of ground injection material and water is 100 to 1000% by weight.
Particularly preferably, it is 300 to 500% by weight. If it is less than 100% by weight, the compressive strength one day after the injection is too large, so that there is no permeation injection property into the voids in the ground. If it exceeds 1000% by weight, the compressive strength one day after injection cannot be obtained.

Here, when the ground has a large void and good injectability, the water ratio is reduced and used. On the contrary, if the void is small and the injection property is poor, the water ratio should be increased before use.

The injection pressure is selected depending on the soil quality, but if the ground is weak, increase the water ratio and inject at a small injection pressure.
On the contrary, when the ground is strong, there is no fear of ground breakage. Therefore, the time required for injection can be shortened by decreasing the water ratio and increasing the injection pressure.

When kneading the ground injection material of the present invention and water, a water reducing agent can be used if necessary. In particular, when a high-performance water reducing agent is used, interparticle agglomeration is eliminated, and as a result, it can be injected as a single particle and a large permeability can be obtained.

Furthermore, if necessary, a foaming agent (eg Al powder), a thickener (eg methylcellulose), an outflow inhibitor (eg sawdust, chaff, etc.), a bulking agent (eg sand), or a foaming agent ( (Example: silicone) and the like can be blended.

As the injection method of the ground injection agent of the present invention, a one-shot method, a 1.5 Ahot method in which a quick-setting material is combined,
All injection methods such as the two-shot method or the forced stirring method can be used.

By the above construction method, the material injected into the ground is different from the conventional material, and even if it is injected into soil exposed to strongly acidic water, hot spring water or high temperature steam, it will be used as a ground injection material for a long time. You can expect an effect. Also,
Since it does not use harmful substances to the human body, it is safe to handle.

〔Example〕

Hereinafter, the present invention will be specifically described in detail with reference to Examples.

Example 1 Blast furnace water frame slag was crushed by a ball mill, and the crushed product was classified (Super Micron manufactured by Hosokawa Micron Co., Ltd.)
In this way, the particle diameter was classified to 15 μm or less to obtain an alkaline hydraulic powder.

Na ₂ CO ₃ as an alkali metal salt and Ca (OH) ₂ as an alkaline earth metal hydroxide are both 15 μm or less, and Na ₂ C 3
A mixture of O ₃ : Ca (OH) ₂ = 1: 1 (weight ratio) was mixed with 14% by weight of alkaline hydraulic powder to prepare a ground injection material.

This is water / ground injection material (hereinafter referred to as W / C) = 100, 300
And 500% by weight to form a paste, 4 × 4 × 16 cm
Was poured into an iron mold and the compressive strength was measured after a predetermined age.

Cement-slag fine powder commercial products were tested as Comparative Examples Nos. 7-9.

<Materials used> Granulated blast furnace slag: Kawasaki Steel Co., Ltd., Mizushima Plant Alkali metal carbonate: Na ₂ CO ₃ (for industrial use) Wako Pure Chemical Industries, Ltd. Alkaline earth metal hydroxide: Ca (OH) ₂ (Industrial) As shown in Table 1 manufactured by Wako Pure Chemical Industries, Ltd., the ground injection material of the present invention has high strength development compared to commercially available products and does not use a strong alkaline substance such as NaOH, so that it is easy to handle. Therefore, it is highly safe for the human body.

Example 2 After using the same material as in Example 1 No. 2 and kneading 200 with a mortar mixer at a water ratio of 300% by weight, pH was 3 and temperature was 40 ° C.
30 minutes per minute using a grout pump in the ground containing hot spring water
Was injected with pressure. When 3 m ^{3 was} injected at this concentration, the injection pressure rose to 7 kg f / cm ² , so the injection was terminated because the water ratio was changed to 600%.

Curtain grout construction was performed by performing 100m ³ of the same injection every 10m in every 1m interval.

The hydraulic conductivity of the ground before the injection was 3.7 × 10 ^-3 (cm / sec), but the same measurement was performed one week after the injection, and the hydraulic conductivity was 5.2 × 10 ^-8 (cm / sec). It was confirmed that the ground was improved.

Three years later, the hydraulic conductivity measured in the area was 5.5 x 10
^{At -8} (cm / sec), there was no difference in the ground improvement effect.

For comparison, when using a cement-slag fine powder type commercial product and performing the same construction at the same place,
The hydraulic conductivity after one week was 4.6 × 10 ⁻⁶ (cm / sec).
One year later, when the same measurement was performed, the hydraulic conductivity was 3.7 × 10
^{At -4} (cm / sec), the effect of ground improvement was hardly recognized.

In addition, commercial products could not be injected with a total injection volume of 20 m ³ .

Example 3 Toyoura standard sand moistened with water was filled in a transparent tube having a pore size of 5 cm and a length of 50 cm, and ground injection corresponding to No. 2 of Example 1 having a particle size of 15 μm or less and a range of 16 to 40 μm was performed. When the water content of each material was 300% by weight, it was possible to inject particles with a particle size of 15μ or less, but it was impossible to inject particles with a particle size of 16-40μ.

〔The invention's effect〕

 The effects of the present invention are as follows.

1) High injection / penetration and durability for acidic soil, hot spring area and high sulfate soil.

2) Compared with commercial products, the compressive strength is high even if the water ratio is high.

3) Easy to handle and highly safe for humans.

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Claims (1)

(57) [Claims] 1. An alkali hydraulic powder having a particle size of 15 μm or less, an alkali metal salt and an alkaline earth metal hydroxide,
Mixing ratio of alkaline hydraulic ground injection material and water is 100-1000
Alkaline hydraulic ground injection material, characterized in that it is in weight%.