JPH08302346A - Solidifier for soil conditioning - Google Patents

Abstract

PURPOSE: To obtain a solidifier useful for obtaining soil which shows a nearly neutral pH when it comes into contact with water, is suited for vegetation, and has an acid resistance. CONSTITUTION: This solidifier mainly consists of 100 pts.wt. anhydrous gypsum, 0.5-10 pts.wt. cure accelerator and 10-200 pts.wt. additive. An example of the cure accelerator is a combination of at least one member selected from among sulfates, hydrogensulfates, nitrates, cements, quick lime and slaked lime. Examples of the additive include blast furnace slag, coal ash, and a combination of both. The solidifier is added in an amount of desirably 1-25 pts.wt. per 100 pts.wt. soil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidifying material for improving soil properties such as soil, sludge, incineration ash, and construction sludge. More specifically, it is a solidifying material for soil improvement which is excellent in strength development and suitable for vegetation. Regarding materials

[0002]

2. Description of the Related Art Conventional solidification materials for soil improvement are mainly composed of cement or quick lime, and if necessary, slaked lime, calcined dolomite, blast furnace slag, etc. are mixed and used. The solidification material for soil improvement is blended in an amount of 30% or more based on the soil material.

[0003]

However, as the conventional solidifying material for soil improvement as described above, at least one kind of cement, quick lime, slaked lime, calcined dolomite, etc. is usually blended in an amount of 30% or more in terms of inner ratio. Therefore, the soil that has been improved and solidified, sludge, incineration ash, etc. dissolves in water and usually shows a high alkalinity of pH 11 or higher, and with the passage of age, the surface of the improved soil becomes close to neutral. However, in the place of 10 cm from the surface, it shows strong alkalinity which is the same as immediately after the improvement. Therefore, the improved solidified product is not suitable for growing plants as it is. Therefore, in order to make it suitable for vegetation, it is necessary to take measures such as covering it with unmodified soil suitable for it, which is a problem in terms of labor and cost.

In addition, conventional solidifying materials for soil improvement are used as acidic soil,
When used in the soil of acidic substances such as peat, hardening is delayed, strength is poorly expressed, and it dissolves after hardening. In addition, acid rain, acidic river water, and acidic liquid gradually dissolve the solidified material, reducing the effect of the solidification treatment, and re-crystallizing the dissolved calcium content to block gutters and drainage channels. Occurs. Therefore, the present inventor has conducted extensive studies in order to eliminate the problems of the above-described conventional soil-improving solidifying materials, and as a result, the solidified material exhibits the required physical properties, and also has a pH value in contact with water. During the search for a material that is almost neutral, it goes without saying that the solidified product exhibits the required physical properties, and the pH becomes almost neutral when it comes into contact with water, making it suitable for vegetation and having acid resistance. The material was found, and the present invention was completed here. Therefore, the problem to be solved by the invention is that the solidified product exhibits the required physical properties, and has a pH that is almost neutral when it comes into contact with water, which is suitable for vegetation and is a soil improvement material that is acid-resistant. It is to provide a solidifying material.

[0005]

Means for solving the above-mentioned problems of the present invention are achieved by the following respective inventions.

(1) Anhydrite, a hardening accelerator, and a solidifying material containing a mixture as a main component, and the ratio of these is anhydrite 1
A solidifying material for soil improvement, which comprises 100 parts by weight, 0.5 to 10 parts by weight of a curing accelerator, and 10 to 200 parts by weight of a mixed material. (2) The soil-improving solidifying material according to the above (1), wherein the hardening accelerator is a combination of one or more of sulfate, hydrogen sulfate, nitrate, cement, quick lime, and slaked lime. (3) The solidified material for soil improvement according to the above item 1 or 2, wherein the mixed material is blast furnace slag, coal ash, or a combination of both.

The present invention will be described in more detail below.
The place to be the gist of the present invention is that the soil improvement solidifying material of the present invention contains anhydrous gypsum, a hardening accelerator, and a mixed material as main components to elute calcium ions and alkaline oi in water to adjust the pH. It is characterized in that the amount of material to be raised is extremely small. Further, the solidifying material for soil improvement of the present invention has a weight ratio of 100 parts by weight of anhydrous gypsum and 0.5 to 10 parts by weight of a curing accelerator of anhydrous gypsum. , Mixed material 10-200
By using the weight part, not only the required physical properties of the soil can be exhibited, but also the strength can be expressed and the acid resistance can be obtained, which is suitable for vegetation.

The anhydrous gypsum used in the present invention may be a calcined product of gypsum dihydrate, a natural product, or an industrial by-product. Even when gypsum dihydrate is heated to give anhydrous gypsum,
It does not need to be heated above 00 ° C and consumes less heat than cement and quicklime during manufacturing. And 500 gypsum dihydrate
What was baked at ℃ -1000 ℃ is desirable from the viewpoint of strength development of the cured product. In this case, if natural products or by-products are used for anhydrous gypsum, heat energy is not required in the manufacturing process. Therefore, it can be said that it is an energy-saving cement. Furthermore, by-products such as anhydrous gypsum, blast furnace slag, and coal ash can be effectively used, and it is a material that greatly contributes to global environmental conservation.

In the present invention, a hardening accelerator is added to accelerate the hardening of the anhydrous gypsum. The hardening accelerator includes potassium sulfate, light vane and other sulfates, sodium hydrogen sulfate and other hydrogen sulfates. , Nitrates such as ammonium nitrate,
Examples include cement, quick lime, and slaked lime, and combinations of one or more of these. Of these, particularly desirable materials are potassium alum and alkaline sulphate, but in the case of potassium alum and alkaline sulphate, white flowers become noticeable when the amount added is large, so the amount added is 5% or less. Is preferred.

Further, the admixture used in the present invention can effectively utilize industrial by-products and can improve the strength of treated soil due to its latent hydraulic property. Blast furnace slag and coal ash are used, and a mixture of both can also be used. In addition, silica fume, volcanic ash, and limestone powder can be used in combination with the mixed material. In the present invention, the soil-improving solidifying material may be used by mixing the above materials, but in order to increase the manifestation of the strength of the improved soil,
It is better to mix and pulverize the prepared materials and reduce the particle size. Soil improvement solidifying material of the present invention, soil, sludge, incinerated ash, construction soil, construction sludge, peat, peat soil can be solidified, the obtained treated soil is suitable for vegetation,
Provides acid resistance and long-term durability. Here, construction sludge cannot be piled up on a standard dump truck among those discharged during excavation work related to construction work other than dredging.
Also, in a state where no person walks on it (Cone index is generally less than 2 or uniaxial compressive strength is 0.5 kgf / cm
² or less) is called construction sludge and corresponds to industrial waste sludge specified by the Waste Management Law.

The component ratio of the solidifying material for soil improvement of the present invention is
By limiting the amount to 100 parts by weight of anhydrous gypsum, 0.5 to 10 parts by weight of a curing accelerator, and 10 to 200 parts by weight of a mixing material, the above-mentioned excellent effects are exhibited, and preferably 100 parts by weight of anhydrous gypsum and cured Accelerator 1 to 8 parts by weight, mixing material 20 to 150 parts by weight, more preferably anhydrous gypsum 1
00 parts by weight, 2 to 5 parts by weight of curing accelerator, 30 to 1 of mixing material
It is 00 parts by weight. When the amount of this hardening accelerator is less than 0.5 parts by weight, sufficient hardening of anhydrous gypsum cannot be accelerated. On the other hand, when the amount of the curing accelerator exceeds 10 parts by weight, the elongation of the curing acceleration effect is reduced. Further, when the amount of the mixed material is less than 10 parts by weight, the strength development in the long-term age is insufficient, and when the amount of the mixed material exceeds 200 parts by weight, the strength development property of the treated soil is deteriorated. The solidifying material for soil improvement of the present invention may be added in an amount usually added to the solidifying material, but preferably 1 to 25 parts by weight with respect to the soil material.
A more preferable addition amount is 3 to 15 parts by weight. The pH of the soil treated with the conventional cement-based or lime-based solidifying agent is 10 or more until 1 week after the treatment, but when the soil-improving solidifying agent of the present invention is used, the pH is 9 even immediately after the treatment.
It is suitable for growing plants without covering with soil because it is as follows.

When the soil improving solidifying material of the present invention is used, if necessary, a naphthalene-based material, a melamine-based material,
Admixture for increasing dispersibility such as polycarboxylic acid type and refined lignin type, resin soap, surfactant such as polyoxyethylene, alkylallyl sulfate, dodecylbenzene sulfonate, waterproofing agent, antifreezing agent, rust preventive agent The additives usually used in this technical field, such as effluent inhibitor, quick-setting agent, etc., can be appropriately mixed and used.

[0013]

[Action]

1) The hardening mechanism of the solidifying material for soil improvement of the present invention is originally using anhydrous gypsum which is extremely slow in hydration. In order to accelerate hardening of this anhydrous gypsum by hydration, a hardening accelerator is used in the first step. When added, water is absorbed in the process of restoring gypsum dihydrate by the stimulation of the hardening accelerator, and hydrates and hardens in a short time. In the second stage, admixtures such as blast furnace slag, soil, sludge, incinerated ash, construction sludge, etc., anhydrous gypsum, gypsum dihydrate, cement,
A hydration reaction (pozzolan reaction) with quick lime and slaked lime causes gradual hardening.

2) When anhydrous gypsum and blast furnace slag are used as main constituent materials, the hydration products are mainly dihydrate gypsum and pozzolanic reaction products, and whether portlandite (Ca (OH) ₂ ) is formed or not. , Even if produced, it is a very small amount. Even when cement, quick lime, or slaked lime is used as a hardening accelerator for this, the pH of the treated soil is close to neutral because the added amount is small.

3) Due to the composition of the solidifying material for soil improvement of the present invention, since portlandite is not generated or is small in amount, the amount of calcium dissolved in the acid is extremely small, and therefore, the re-dissolved calcium content is regenerated. There is no problem such as blocking the drainage channel due to crystallization.

4) The anhydrous gypsum used in the present invention is more hydrated at lower temperatures unless it is frozen, so that it exhibits excellent strength development and has a short curing time. Therefore, it is a material suitable for soil improvement work in winter and cold regions. 5) When the construction sludge is solidified with the solidifying material of the present invention, the corn index is approximately 2 or more or the uniaxial compressive strength is 0.5 k.
It becomes gf / cm ² or more. In addition, the pH of the elution water from the improved soil is close to neutral, and the pH is within the permissible limit of pH 5.
It will be within 8 to 8.6 (5.0 to 9.0 in the sea area). As described above, it does not cause any trouble in maintaining the living environment, and can be reused as a backfill material or the like.

[0017]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Sandy clay (water content ratio 31.9%, unit volume weight 1.813 g / cm ³ ) which is wet soil was used as the target soil for the soil material, and the solidification material for soil improvement was As anhydrous gypsum, by-product anhydrous gypsum, using three kinds of products heated at 500 ° C. and 1000 ° C., anhydrous potassium alum (Wako Pure Chemical Industries, Ltd., potassium aluminum sulfate) as a curing accelerator, mixed agent As the blast furnace slag (manufactured by Mitsubishi Materials Corp., Blaine value 6050 cm ² / g) was used. The solidifying material having the material composition shown in Table 1 was added to the wet soil in an amount of 5%, and mixed for 10 minutes by a Hobart type mixer. This was put into a vegetation box and compacted to obtain vegetation soil. A 2.5 kg rammer was used for compaction. As of the 7th day of the material age, the seeds of Zinnia and Okuura were sowed, and then watering and topdressing were appropriately performed, and the state of growth until two months later was observed. Further, the pH of the vegetation soil was measured (according to JSF T7) and the uniaxial compression test (according to JIS A1216) of the treated soil was conducted on the 7th and 28th days. For the uniaxial compressive strength test, diameter 5 cm, height 1
Using a 0 cm mold, a specimen was prepared so as to have the same degree of compaction as the vegetation soil, and was cured in a thermostatic chamber at 20 ± 3 ° C. for use. As a solidifying material for comparison, a cement-based solidifying material "Stabilite M15" manufactured by Mitsubishi Materials Corp.
Was used by adding 5.5%. The test results are shown in Table 2. The vegetation soil treated with the solidifying material of the present invention has a lower pH than the soil treated with the cement-based solidifying material, and has good plant growth. Further, there is no problem in the expression of uniaxial compressive strength. Solidifying material No. The reason why the plant growth was slightly poor in No. 3 is considered to be that the strength expression of the treated soil was good.

[0019]

[Table 1]

[0020]

[Table 2]

Example 2 As a target soil, sandy clay which is a wet soil (water content ratio 31.9)
%, Unit volume weight 1.813 g / cm ³ ) was used.
As the solidifying material for soil improvement, anhydrous gypsum, which is a by-product, is heated at 500 ° C. as anhydrous gypsum, anhydrous potassium alum (manufactured by Wako Pure Chemical Industries, Ltd.) as a curing accelerator, and sodium hydrogen sulfate hydrate ( Wako Pure Chemical Industries, Ltd., reagent special grade, ammonium nitrate (Wako Pure Chemical Industries, Ltd. reagent special grade), ordinary Portland cement (Mitsubishi Materials Corp.), quicklime (Rishikou Lime Industry Ltd.) , Brain 3560 cm ²
/ G), fly ash (Matsushima Thermal Power Co., Ltd., Blaine value 2960 cm ² / g) was used as a mixed material. 4 to No. A sample of the solidified material of No. 8 was prepared.
The solidifying material having the material composition shown in Table 3 is shown. The test content and method were the same as in Example 1. The test results obtained are shown in Table 4. The vegetation soil treated with the solidifying material of the present invention has a pH lower than that of the soil treated with the cement-based solidifying material and is close to neutral, and the growth of plants is good. Further, there is no problem in the expression of uniaxial compressive strength.

[0022]

[Table 3]

[0023]

[Table 4]

Example 3 As a target soil, wet soil such as peat (water content ratio: 590%,
A unit volume weight of 1.040 g / cm ³ ) was used. As a solidifying material for soil improvement, 5 g
Heated product at 00 ° C, anhydrous potassium alum (manufactured by Wako Pure Chemical Industries, Ltd.) as a curing accelerator, fly ash (Matsushima Thermal Power, Blaine value 2960 cm ² / g) as a mixture,
Silica fume (manufactured by Elchem, BET specific surface area 21 m
² / g), pulverized ash (from Kagoshima, Blaine value 39)
10 cm ² / g), blast furnace slag (Mitsubishi Materials Corporation)
Manufactured) and a Blaine value of 6050 cm ² / g) were used in combination. The solidifying material having the material composition shown in Table 5 was added to the peat at 250 kg / m ³ , and Example 1
Tested in the same way as. The test results are shown in Table 6. The vegetation soil treated with the solidifying material of the present invention has a pH lower than that of the soil treated with the cement-based solidifying material and is close to neutral, and the growth of plants is good. The uniaxial compressive strength is well expressed.

[0025]

[Table 5]

[0026]

[Table 6]

Example 4 Construction sludge (water content 95%, unit volume weight 1.516 g / cm ³ ) was used as the target soil. As a solidifying material for soil improvement, by-product anhydrous gypsum heated at 500 ° C, anhydrous potassium alum as a hardening accelerator (Wako Pure Chemical Industries, Ltd.)
Fly ash (manufactured by Matsushima Thermal Power Co., Ltd., Blaine value 2960 cm ² / g), blast furnace slag (manufactured by Mitsubishi Materials Corp.), and Blaine value 6050 cm ² / g) were used as a mixed material. The solidifying material having the material composition shown in Table 7 was added to the construction sludge at 100 kg / m ³ and tested in the same manner as in Example 1. Table 8 shows the test results. Further, on the day after the treatment, water was exuded through a hole formed in the bottom of the vegetation box, and water was evenly and gradually sprinkled on the three types of treated soil with a watering can, and elution water was collected and the pH thereof was measured. The improved soil treated with the solidifying material of the present invention had a pH lower than that of the soil treated with the cement-based solidifying material, resulting in 8.2. The pH of the elution water is 5.9 to 6.9, which is an allowable limit of pH 5.
It was within the range of 8 to 8.6 (5.0 to 5.9 in the sea area). Actually, the elution water passes through the soil around the improved soil, so that the alkaline components are adsorbed to the soil, and
Will not affect the surrounding area. Furthermore, the growth of plants is also good.

[0028]

[Table 7]

[0029]

[Table 8]

[0030]

EFFECTS OF THE INVENTION The treated soil treated with the solidifying material for soil improvement of the present invention not only exhibits good strength development but also provides acid-resistant soil material. Will not be blocked and p of treated soil
Since H is close to neutral even immediately after the treatment, it is suitable for growing plants, and since the pH of the water eluted from the treated soil is close to neutral, the living environment can be preserved, which is an excellent effect.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location E02D 3/12 E02D 3/12 // C09K 103: 00 (72) Inventor Toyichi Nishida Omiya, Saitama Prefecture 1-297 Kitabukuro-cho, Ichi, Japan Mitsubishi Materials Corporation Cement Research Center

Claims (3)

[Claims] 1. A solidifying material mainly composed of anhydrous gypsum, a hardening accelerator and a mixed material, the proportion of which is 100 g of anhydrous gypsum.
Parts by weight, 0.5 to 10 parts by weight of curing accelerator, and admixture 10
~ 200 parts by weight, a solidifying material for soil improvement. 2. The solidification material for soil improvement according to claim 1, wherein the hardening accelerator is a combination of one or more kinds of sulfate, hydrogen sulfate, nitrate, cement, quick lime, and slaked lime. 3. The mixed material is blast furnace slag or coal ash, or a combination of both.
Alternatively, the solidifying material for soil improvement according to claim 2.