JP2002088364A - Grouting material having lowered elution of hexavalent chromium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grouting material having excellent permeability and strength development and effective for suppressing the elution of hexavalent chromium from powdery cement. SOLUTION: The objective grouting material having lowered elution of hexavalent chromium contains powdery cement, powdery slag and calcium aluminosilicate. The grouting material may further contain gypsum and optionally a reducing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low hexavalent chromium injection material for reducing elution of hexavalent chromium contained in fine particle cement. The parts and percentages used in the present invention are based on mass unless otherwise specified.

[0002]

2. Description of the Related Art Injectable materials currently used in the field of civil engineering and construction are roughly classified into water glass-based injectable materials and cement-based injectable materials. Although the permeability of the water glass-based injection material is better than that of the cement-based injection material, there is a problem that the durability is poor. In addition, the silt layer and the clay layer have a poor permeability even when a water glass-based injection material is used, and the water glass-based injection material enters the wedge shape into the silt layer or the clay layer by liquid pressure, which is a so-called split injection mode. Become. However, the water glass based injection material has its own compressive strength (homogel strength).
In some cases, it was not possible to obtain the effect of reinforcing the ground or stopping water because of the small size.

[0003] In recent years, an injection material has been developed in which cement particles have been made into fine particles to improve the permeability of the cement-based injection material. Can be obtained.

On the other hand, the cement industry is expected to treat various types of industrial waste, and the use of industrial waste such as sewage sludge and old tires for the production of cement has been continued. Its usage is expected to increase. Accordingly, there is a concern that the content of harmful components contained in cement, in particular, hexavalent chromium, may increase.

In order to fix hexavalent chromium,
A method of adding blast furnace slag or adding ferrous sulfate has been studied (JP-A-2000-086322). However, when the cement is micronized to improve the permeability by this method, the specific surface area increases, the amount of hexavalent chromium eluted increases, and the time until hardening is several hours. For example, elution and diffusion of hexavalent chromium cannot be improved, and there is a problem that a sufficient effect cannot be obtained.

[0006] The present inventor has obtained the finding that the use of a specific material in combination with fine particle cement can reduce the elution amount of hexavalent chromium, and has completed the present invention.

[0007]

That is, the present invention is a low hexavalent chromium injecting material containing fine particle cement, fine particle slag, and calcium aluminosilicate, and further contains gypsum and a reducing agent. The low hexavalent chromium-implanted material.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

As the fine particle cement used in the present invention, various kinds of Portland cements such as ordinary, fast and ultra-high strength are finely divided, and these finely divided Portland cements include, for example, a Blaine specific surface area.
Cement mixed with fly ash, limestone, silica sand, or the like, which has a particle size of 5,000 cm ² / g or more (hereinafter referred to as a Blaine value), may be used. The particle size of the particulate cement is
Preferably 5,000 cm ² / g or more in Blaine value, more preferably at least ^{8,000cm 2 / g, 12,000cm 2 /} g or more it is most preferred.
If it is less than 5,000 cm ² / g, the permeability may be poor.

The fine particle slag used in the present invention is obtained by making blast furnace slag or converter slag into fine particles.
Of these, those obtained by quenching the blast furnace slag to form fine particles of vitreous material are preferable from the viewpoint of strength development. The particle size of the particulate slag is preferably 5,000 cm ² / g or more in Blaine value, more preferably at least ^{8,000cm 2 / g, 12,000cm 2 /} g or more is most preferred. If it is less than 5,000 cm ² / g, the permeability may be poor. The amount of fine particle slag used is fine particle cement
For 100 parts, 50 to 1,000 parts is preferable, and 200 to 500 parts is more preferable. If the amount is less than 50 parts, the fixation ratio of hexavalent chromium may decrease, and if it exceeds 1,000 parts, the initial strength may decrease.

The calcium aluminosilicate used in the present invention
(Hereinafter referred to as CAS) is quicklime (CaO), slaked lime (Ca
(OH)_Two) And limestone (CaCO_Three), Etc.
Mina, bauxite, diaspore, feldspar, clay, etc.
Alumina raw materials, silica stone, silica sand, quartz, and diatoms
After mixing silica materials such as soil at a predetermined ratio, the rotor
Fired in a re-kiln or electric furnace or high-frequency furnace
It is manufactured by melting. Or economical
Blast furnace granulated slurs by-product in metallurgy, metal refining, etc.
Or Portland cement, etc.
It can also be manufactured by blending and heat treating. C
CaO content in AS is 20-60%, Al_TwoO_ThreeContent is 20-70
%, SiO_TwoThe content is preferably 5 to 30%, and the CaO content is 30 to 60%.
%, Al_TwoO_Three25-60% content, and SiO_Two10-25% content
More preferred. Out of this range, strength development and hexavalent chromium
May be inferior in immobilization rate. In addition, CaO, Al_TwoO_Three,as well as
SiO_TwoSome of them are alkali metal oxides and alkaline earth metals
Oxides, alkali metal halides, alkaline earth metals
Halides, alkali metal sulfates and alkaline earths
Compounds substituted with metal sulfates, or CaO, Al
_TwoO_Three, And SiO_TwoThese are dissolved in
Substances included in the CAS of the present invention. CAS specific
As the compound, 2CaO.Al_TwoO_Three・ SiO_TwoAnd CaO / Al_TwoO_Three・ 2SiO_TwoWhat
Etc., especially the vitreous material obtained by quenching the melt
Are more preferred. The vitrification rate of CAS is higher
It is preferable from the viewpoint of improving the fixing ratio of hexavalent chromium. Ingredient
Physically, 50% or more is preferable, and 80% or more is more preferable
And 90% or more is most preferable. The measurement of the vitrification rate
The method is as follows: CAS is heated at 1,000 ℃ for 2 hours, then 5 ℃ / min
At a cooling rate of 2. The X-ray powder diffraction method
Main peak area S ₀For the CAS crystal main
From the peak area S, X (%) = 100 × (1−S / S ₀Expression
The vitrification rate X was obtained by the following. The particle size of the CAS
5,000cm^Two/ g or more is preferable, and 8,000 cm^Two/ g or more
Is more preferable. 5,000cm^TwoIf less than / g, permeability deteriorates
There is. The amount of CAS used is based on 100 parts of fine particle cement.
And preferably 1 to 200 parts, more preferably 10 to 50 parts.
No. If it is less than 1 part, the fixation rate of hexavalent chromium will be small.
Even if it exceeds 200 parts, the fixation rate of hexavalent chromium
No further improvement can be expected.

In the present invention, it is preferable to use gypsum in combination in order to further improve strength development. Examples of the gypsum used in the present invention include anhydrous gypsum, hemihydrate gypsum, gypsum and the like, and further, natural gypsum, phosphate gypsum, drainage gypsum, and chemical gypsum such as hydrofluoric gypsum, Alternatively, gypsum obtained by heat-treating these may be used. Of these, anhydrous gypsum is preferred in terms of high strength development. The gypsum particle size is preferably 5,000 cm ² / g or more in Blaine value,
It is more preferably at least 8,000 cm ² / g. If it is less than 5,000 cm ² / g, the permeability may be poor. The amount of gypsum used is preferably 0.1 to 100 parts with respect to 100 parts of fine particle cement, and 1 to 30 parts.
Parts are more preferred. If the amount is less than 0.1 part, the initial strength manifestation property may decrease, and if it exceeds 100 parts, the immobilization ratio of hexavalent chromium may decrease.

Further, in order to improve the fixation ratio of hexavalent chromium, it is preferable to use a reducing agent in combination. Examples of the reducing agent used in the present invention include sulfates such as divalent iron salts such as iron (II) sulfate and trivalent titanium salts such as titanium (III) sulfate, sodium sulfite, potassium sulfite, and calcium sulfite. Bisulfites, such as sodium bisulfite and potassium bisulfite, sodium sulfite,
There are sulfides such as potassium sulfide, calcium sulfide and ammonium sulfide, thiosulfates such as sodium thiosulfate and potassium thiosulfate, sulfur dioxide and sulfur, and peat and lignite. Use of iron (II) sulfate, sodium thiosulfate, and potassium thiosulfate is preferred in view of the high immobilization rate of The amount of the reducing agent used is preferably 0.01 to 50 parts, more preferably 0.1 to 5 parts, based on 100 parts of the fine particle cement. If the amount is less than 0.01 part, the immobilization rate of hexavalent chromium may decrease, and even if the amount exceeds 50 parts, a further improvement in the immobilization rate of hexavalent chromium cannot be expected.

Further, in the present invention, it is preferable to use a setting modifier together in order to adjust so that a required curing time is obtained. As the setting regulator, specifically,
Aluminates such as sodium aluminate and potassium aluminate, carbonates such as sodium carbonate and potassium carbonate, hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide, aluminum sulfate, and iron sulfate (III) and sulphates such as alum, silicates such as sodium silicate, potassium silicate and lithium silicate, silicates such as sodium silicate and magnesium silicate, sodium phosphate, calcium phosphate and phosphoric acid Inorganic salts such as phosphates such as magnesium, borates such as lithium borate and sodium borate, citric acid, gluconic acid, tartaric acid,
And sodium salts, potassium salts, lithium salts, and calcium salts thereof, and organic acids such as malic acid, and saccharides. The amount of the setting modifier used is not particularly limited since it is adjusted according to the curing time, but is preferably 0.01 to 50 parts with respect to 100 parts of the fine particle cement.

Further, in order to improve the permeability, it is preferable to use a dispersant in combination. As dispersants, naphthalene sulfonic acid formalin condensate salt type, lignin sulfonate type, melamine sulfonic acid formalin condensate salt type,
Polycarboxylate and polyether dispersants are preferred. The amount of the dispersant to be used is preferably 0.01 to 10 parts, more preferably 0.1 to 3 parts, per 100 parts of the fine particle cement. If it is less than 0.01 part, the permeability may be poor, and if it exceeds 10 parts, the initial strength may be reduced.

The low hexavalent chromium injection material of the present invention (hereinafter referred to as the injection material) contains fine cement, fine particle slag, and CAS, and further, if necessary, gypsum and a reducing agent. Water can be mixed to form a suspension and injected into the ground or the like. The amount of the injection material used varies depending on the type of soil, water content, and required strength, etc., and is not determined uniformly, but usually ⁵ to 300 kg per 1 m3 of soil. Preferably, 50-150 kg is more preferable. If it is less than 5 kg, the solidification strength may be low, and if it exceeds 300 kg, the solidification strength may be too large.

The amount of water when the present injection material is used as a suspension is not particularly limited as long as the suspension has a viscosity that can be pumped by a pump. For example, for a total of 100 parts of particulate cement, particulate slag, CAS, gypsum, and reducing agent, 1
The amount is preferably from 00 to 1,000 parts, more preferably from 200 to 500 parts. 1
If it is less than 00 parts, the viscosity may be too high, and 1,000
If the amount exceeds the limit, the solidification strength may decrease.

When the injection material is mixed with water to be used as a suspension, fine cement, fine slag, CAS and water, and, if necessary, gypsum and a reducing agent are blended, mixed with a mixer, and pumped. It is also possible to inject into the ground in one shot. In this case, since the present injection material may be cured by a mixer, a pump, a hose, or the like, it is necessary to secure a curing time of at least 30 minutes or more. Therefore, for example, a suspension composed of fine-particle cement, fine-particle slag, and water, and, if necessary, a suspension composed of gypsum and a reducing agent are separately prepared, and two types of suspensions are prepared. A so-called 1.5 shot injection method of mixing and injecting with a Y-tube, or a so-called 1.5 shot injection method, or separately mixing and injecting at the tip of a double tube for injection and so-called injection It is more preferable to inject into the ground by an injection method of two shots.

Further, the present injection material includes a material separation resistance material such as bentonite, allophane, methylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose and polyvinyl alcohol; a foaming agent such as gelatin, casein and metallic aluminum; It is also possible to use an antifoaming agent such as silicone in combination.

The injection material is used for injection methods currently used, such as a single pipe rod method, a single pipe strainer method, a double pipe single phase method, a double pipe double phase method, and a double pipe double packer method. It is possible to

[0021]

EXAMPLES Hereinafter, the present invention will be further described with reference to experimental examples of the present invention, but the present invention is not limited thereto.

Experimental Example 1 Fine particles slag, CAS, and gypsum shown in Table 1 were mixed with 100 parts of fine particle cement to prepare an injection material.
A suspension was prepared by mixing 100 parts of the prepared injection material and 300 parts of water, and the curing time, compressive strength, and hexavalent chromium elution amount of the injection material were measured. The results are also shown in Table 1.

<Materials Used> Fine particle cement: Finely pulverized ordinary Portland cement,
Blaine value 12,500cm ² / g Fine particle slag: Rapidly cooled blast furnace slag finely pulverized product, Blaine value 1
3,000 cm ² / g CAS A: glass having a composition of 45% CaO, 40% Al ₂ O ₃ and 15% SiO ₂ , vitrification rate 95%, Blaine value 8,500 cm ² / g CAS B: 45% CaO, Al ₂ O ₃ Glass with composition of 28% and SiO ₂ 27%, vitrification rate 95%, Blaine value 8,500cm ² / g Gypsum: natural anhydrous gypsum, Blaine value 9,000cm ² / g

<Test method> Curing time: Time until the suspension does not flow even if the suspension is put in a cup and tilted Compressive strength: Measured in accordance with JIS R 5201;
28 days Hexavalent chromium elution amount: Measured according to the Notification of the Environment Agency No. 46, 1 and 28 days old

[0025]

[Table 1]

Experimental Example 2 400 parts of fine slag, C
The same procedure as in Experimental Example 1 was carried out except that this injection material was prepared by mixing 20 parts of AS-A and gypsum and a reducing agent shown in Table 2.
The results are also shown in Table 2.

<Materials used> Reducing agent a: iron (II) sulfate, commercially available reducing agent b: sodium sulfite, commercially available reducing agent c: sodium bisulfite, commercially available reducing agent d: sodium sulfide, commercially available reducing agent e : Sodium thiosulfate, commercial product Reducing agent f: potassium thiosulfate, commercial product Reducing agent g: sulfur, commercial product

[0028]

[Table 2]

Experimental Example 3 No. 7 silica sand was placed in a polyethylene tube having a diameter of 5 cm and a length of 30 cm until the height became 20 cm. On the other hand, fine particle cement 10
0 parts, 400 parts of particulate slag, 20 parts of CAS, 20 parts of gypsum,
1 part of the setting regulator and 1 part of the dispersant shown in Table 3 were mixed,
This injection material was prepared. A suspension was prepared by mixing 100 parts of the prepared injection material and 300 parts of water, and the suspension was gently poured into a polyethylene tube containing sand, and the penetration length into the sand,
Compressive strength and hexavalent chromium elution amount were measured. The results are also shown in Table 3.

<Materials used> Setting regulator A: sodium aluminate, reagent Setting regulator B: potassium carbonate, reagent Setting regulator C: sodium silicofluoride, reagent Setting regulator D: citric acid, reagent Dispersant: powder type Commercial product, polyether type

<Measurement method> Penetration length into sand: After one day, the cured product was taken out of the polyethylene tube, and the length of the cured product was defined as the penetration length.

[0032]

[Table 3]

[0033]

As described above, by using the low hexavalent chromium injection material of the present invention, (1) the elution amount of hexavalent chromium can be reduced. (2) Excellent permeability. (3) Excellent strength development. It produces effects such as:

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Claims (3)

[Claims] 1. A low hexavalent chromium injection material containing fine particle cement, fine particle slag, and calcium aluminosilicate. 2. A low hexavalent chromium injection material containing fine particle cement, fine particle slag, calcium aluminosilicate, and gypsum. 3. The method according to claim 1, further comprising a reducing agent.
Or the low hexavalent chromium injection material according to 2.