JP2010065158A - Soil-based solidifying material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil-based solidifying material using calcium aluminate slag with soil such as decomposed granite soil, in which elution of F and heavy metal such as Pb and Se from the soil-based solidifying material is stably controlled to meet the environmental quality standards for soil. <P>SOLUTION: The soil-based solidifying material for paving by mixing a solidifying material with natural soil is prepared by mixing calcium aluminate slag, gypsum and calcium sulfide as a solidifying material, in which elution from the mixed soil (soil-based solidifying material) is stably controlled to meet the environmental quality standards for soil. Strength of the soil-based solidifying material is effectively maintained while elution can be suppressed by compounding 100 parts by mass of calcium aluminate slag with 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide and controlling the composition of the calcium aluminate slag in such a manner that the total content of CaO and Al<SB>2</SB>O<SB>3</SB>is not less than 70% and CaO/Al<SB>2</SB>O<SB>3</SB>ranges from 1.5 to 2.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a soil-based solidified material in which a solidified material is mixed with soil.

  In the following description, the solidified material is a solidified material mixed with soil for earth-based pavement, and the solidified material itself does not include soil. The same applies to the solidified material for soil paving. The earth-based solidifying material refers to a mixture of soil and the above-mentioned solidifying material. Soil-based solidification material is sometimes called mixed soil.

  On dirt roads and sidewalks, not only can ridges and dents occur due to traffic, making it impossible to drive comfortably and walk safely, but also it is possible to puddle the pits and dents when it rains, so asphalt pave the road It has become. However, asphalt pavement has poor water permeability and water pools. In addition, the pavement surface easily accumulates heat in summer, which causes a heat island phenomenon. Therefore, water-permeable asphalt pavement with improved water permeability of asphalt and water-retentive asphalt pavement with water retention are spreading. It becomes a landscape, and the road surface is hard and the repulsion is strong. Therefore, in recent years, earth-based pavement that is closer to nature and is more human-friendly is being introduced.

  Soil-based pavement uses natural soil and mixes with a solidifying material to increase the strength of the soil and to exhibit its function as a pavement while maintaining the goodness of the soil. Conventionally, cement-based solidified materials using cement as a main raw material and lime-based materials using lime as a main raw material have been mainstream as solidifying materials used for soil-based pavement, but recently solidified materials using slag are also seen.

  In Patent Document 1, after mixing and mixing the soil mixed with soil and soil-based pavement solidifying material in the pavement place, the soil-based pavement solidifying material does not include a porous material in the soil-based pavement that is rolled and cured. It discloses that it contains slaked lime and slag. The mixed soil containing slaked lime and slag solidifies at room temperature, solidifies with strength and hardness not as low as those made of conventional asphalt and not as low as those made of natural soil only. . According to Example 1, 100 parts by mass of slaked lime, 50 parts by mass of clay, and 50 parts by mass of blast furnace slag were mixed to obtain a solidified material for soil-based pavement, and the soil-based pavement solidified material was added to the soil at the pavement site. As a result of pavement construction, it has sufficient strength and ensures water permeability.

  Moreover, there exists what has hydraulic property only in slag, for example, in patent document 2, the slag itself is provided as a hydraulic composition by selecting the slag which has the specific component range of a calcium aluminate-type slag.

  The natural soil used for soil-based pavement is mostly sandy soil that is granulated from granite and is generally called granite. It is generally called sandy-sand pavement and has excellent water permeability. In addition, granular crushed stone and soil collected from production areas near the pavement site are also used. Most of the pure sand soil does not have alkalis such as sodium and potassium, and the pH of the eluate is 5 to 6 and is acidic. However, depending on the place of origin, the pH of the eluate may be about 9 alkaline, and the elution component measured by the Environmental Agency Notification No. 46 method is nearly 0.6 mg / liter in F. Some liters or less pass but are close to the limit. Using soil that shows such alkalinity and mixing a slag-based solidified material containing a slight amount of F with this soil to form a solid-based solidified material, and using this soil-based solidified material, try to pave true sandy soil. In this case, when the elution of the soil-based solidifying material is confirmed, the pH of the eluate is as high as 11 to 12, the elution of F may exceed the soil environment standard, and heavy metals such as Pb and Se due to the increase in pH. The elution of is easily detected and cannot be used as a paving material. It is necessary to ensure the quality of the soil-based solidifying material used for the sand sand pavement, etc., which satisfies the soil environmental standards and can be used safely.

As a method for suppressing the elution of F from the soil, (1) a method of solidifying with cement, for example, a method of kneading waste with cement and adsorbing and immobilizing heavy metal to calcium silicate hydrate, (2 ) A method of treating with a chemical, for example, sodium sulfide suppresses dissolution due to insolubilization of Cd, Pb, Hg, ferrous sulfate suppresses Cr ⁶⁺ elution, ferric chloride suppresses As elution, (3) A method of processing by adding materials such as slag and gypsum, for example, in Patent Document 3, alkali containing blast furnace slag fine powder, gypsum, and calcium in contaminated soil containing Cr ⁶⁺ , As, Se, Cd, and Hg There exists a method of suppressing the said elution from a contaminated soil by mixing a material, specifically, slaked lime.

  (1) In the cement-based solidified material, elution is easily detected depending on the soil used as described above, and there is a risk that hexavalent chromium contained in the cement is also eluted. (2) In the method of treating the medicine, the cost burden of the medicine is large, and there is a risk that harmful gas caused by the medicine is generated when mixing with the soil. (3) The method of adding materials such as slag, gypsum, etc. is applied to the soil-based solidified material targeted by the present invention. Not right. Moreover, since the processing method according to the characteristic of an elution element differs, the universal process which can suppress all the elution elements is difficult, and especially elution of heavy metals, such as F, Pb, and Se, cannot be suppressed simultaneously.

JP 2004-52536 A JP 2006-89337 A JP 2002-320954 A

  The present invention stabilizes the elution of heavy metals such as F, Pb, and Se in the soil-based solidified material in a soil-based solidified material using calcium aluminate-based slag as a solidified material in soil such as sand sand. The purpose is to provide a soil-based solidified material that has been controlled.

  The present invention, in addition to calcium aluminate slag, in the soil where elution of soil solidification material mixed with calcium aluminate slag exceeds the environmental standards due to the characteristics of the soil used for sand sand pavement By mixing gypsum and calcium sulfide at a specific ratio, F is insolubilized, and the pH of the eluate is controlled to suppress elution of heavy metals, and further adjusted to subtle conditions for fixing heavy metals with calcium sulfide. Thus, it has been found that the elution of heavy metals such as F, Pb, and Se in the earth-based solidified material mixed with these solidified materials is suppressed to the soil environment standard or less.

That is, the gist of the present invention is as follows.
(1) Calcium aluminate-based slag, gypsum and calcium sulfide are blended into the soil, and 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide with respect to 100 parts by mass of calcium aluminate-based slag. A soil-based solidifying material characterized by being in the range of.
(2) The composition of the calcium aluminate-based slag is 70% by mass or more in total of the contents of CaO and Al ₂ O ₃ and CaO / Al ₂ O ₃ is 1.5 to 2.0. The earth-based solidifying material according to (1) above.
(3) The soil system according to (1) or (2) above, wherein 5 to 20 parts by mass of a total of calcium aluminate slag, gypsum and calcium sulfide is blended with respect to 100 parts by mass of the soil. Solidified material.

In the present invention, calcium aluminate-based slag is steel slag produced as a by-product in the production process of steel, and is a high-alumina-containing slag produced when aluminum is used as a deoxidizer for molten steel, the main mineral of slag The slag is characterized in that the composition is calcium aluminate such as 12CaO · 7Al ₂ O ₃ .

  Furthermore, the solidifying material in the present invention is a solidifying material mixed with soil for earth-based pavement, and the solidifying material itself does not contain soil. The earth-based solidifying material refers to a mixture of soil and the above-mentioned solidifying material. Soil-based solidification material is sometimes called mixed soil.

  The present invention relates to a soil-based solidified material in which a solidified material mainly composed of calcium aluminate-based slag is mixed with soil such as sand sand, and elution of heavy metals such as F, Pb, and Se from the soil-based solidified material It is a soil-based solidified material that is stably controlled within the standard and has strength and water permeability. By using this soil-based solidified material, surface layers such as roads, sidewalks, playgrounds, and stadiums can be paved.

  The soil-based solidifying material of the present invention is obtained by blending calcium aluminate-based slag, gypsum, and calcium sulfide into soil. The reason for using calcium aluminate slag is that when calcium aluminate slag and gypsum are blended, excellent properties as a soil-based solidifying material can be exhibited.

In the melting of molten steel in the steel manufacturing process, when aluminum is used as a deoxidizer for molten steel, Al ₂ O ₃ is generated in the slag. The composition of the slag including Al ₂ O ₃ is, for example, a calcium aluminate system containing CaO: 50% by mass, Al ₂ O ₃ : 30%, SiO2: 4%, and other MgO in melting of stainless steel. Slag is formed. These slag compositions vary greatly depending on operating conditions such as the melting method.

  Calcium aluminate-based slag is economical because slag can be used as it is by selecting steel slag by-produced in the iron production process into a specific component range.

  The slag is mixed with gypsum and calcium sulfide, mixed with soil and added with water to harden and emit strength. A mixture of soil, the slag, gypsum, and calcium sulfide in an appropriate amount according to the characteristics of the soil can be provided as a soil-based solidifying material, and paving can be performed by simply adding water.

  However, depending on the soil production area, some of the eluate has an alkalinity of about 9 and the elution component measured by the Environment Agency Notification No. 46 method is also detected by F at nearly 0.6 mg / liter, which is 0. Below 8 mg / liter, some pass but are close to the limit. When using this type of soil and pavement with pure sand using a soil-based solidification material mixed with a slag-based solidification material containing a small amount of F, elution from the mixed soil (soil-based solidification material) When confirmed, the pH of the eluate is as high as 11 to 12, the elution of F may exceed the soil environmental standards, and the elution of heavy metals such as Pb and Se can be easily detected by increasing the pH. Cannot be used as It is necessary to ensure the quality of the materials used for the sand sand pavement, etc., which satisfies the soil environmental standards with the mixed soil used for the pavement and can be used safely.

  The present invention is a soil-based solidifying material in which calcium aluminate-based slag, gypsum and calcium sulfide are mixed and soil is mixed, and the elution from the mixed soil (soil-based solidifying material) is stabilized within the soil environment standard. A controlled soil-based solidifying material is provided.

  Here, soil is soil that is naturally collected, such as what is called true sand soil that has been weathered from granite that is often harvested in Japan, and other granular crushed stones, soil, etc. collected from production areas near the pavement site. is there. These are often used for sidewalks, parks, grounds, on-site gardens and parking lots. In addition, these collected soils are mixed with sand, crushed stones, slag aggregates, tiles, glass, wood chips, rubber and other materials that have been crushed and adjusted in particle size to make full use of properties such as color tone, texture, and landscape. Contains mixed soil.

  In the earth-based solidified material in which calcium aluminate slag, gypsum and calcium sulfide are mixed in the soil of the present invention, the blending ratio is 50 to 150 parts by mass of gypsum with respect to 100 parts by mass of calcium aluminate slag, calcium sulfide. It is necessary to contain 2.5-10 mass parts.

  Hydrates in which gypsum is added to calcium aluminate slag and mixed form ettringite, and the strength can be further increased than the compressive strength of the solidified product when calcium aluminate slag is used alone. Therefore, there is an effect of reducing the ratio of these mixed solidifying materials blended in the soil. Furthermore, in the elution test by the Environment Agency Notification No. 46 from mixed soil (soil-based solidified material) mixed with soil by adding gypsum to calcium aluminate slag, the pH of the eluate is kept low to suppress elution. effective.

  When calcium aluminate-based slag alone is used as the solidifying material, in the elution test by the Environment Agency Notification No. 46 from the mixed soil (soil-based solidifying material) in which the solidifying material is mixed with the soil, the pH of the eluate is about 12 In the case of an earth-based solidified material using a type of true sand, for example, alkaline soil, F, Pb, Se, etc. are easily eluted and detected. The elution of any element has a correlation with the pH, and it is necessary to lower the pH in order to suppress the elution.

  When mixing soil and solidified material to make a soil-based solidified material, mix the appropriate amount of gypsum with calcium aluminate-based slag as the solidified material, thereby lowering the pH of the eluate from the soil-based solidified material to the elution suppression range. I found out that I could do it. It is appropriate that calcium aluminate-based slag is 50 to 150 parts by mass of gypsum with respect to 100 parts by mass. If the amount of gypsum is less than 50 parts by mass, it is difficult to uniformly mix and the stability of pH control is lacking. If the amount of gypsum is more than 150 parts by mass, the amount of gypsum for effectively producing ettringite will be too large, and the increase in strength due to the combination of calcium aluminate slag and gypsum will not be seen, and in the stable region Entering and elution cannot be suppressed stably. The composition of gypsum is particularly effective in suppressing the elution of F. Since gypsum suppresses an increase in the pH of the eluate from calcium aluminate-based slag, the amount of Ca dissolved in the eluate increases. In this range, the elution of F can be stably prevented. It is desirable to blend in the range of 80 to 120 parts by mass of gypsum.

  Furthermore, the elution of Pb and Se can be suppressed by lowering the pH of the eluate, but the stability of the control to below the soil environmental standard is lacking, and the elution of Pb and Se is prevented with gypsum alone. I can't do it.

  In order to stably prevent the elution of Pb and Se, calcium aluminate-based slag is added to 100 parts by mass of gypsum in addition to 50 to 150 parts by mass, and further 2.5 to 10 parts by mass of calcium sulfide. It is appropriate to do. Calcium sulfide can suppress the elution by controlling the pH of the eluate, reduce the remaining elution elements, and stably control the elution amount of the components to be below the soil environment standard. If the calcium sulfide is less than 2.5 mass, the reduction is insufficient and the elution cannot be suppressed stably. Moreover, when it mixes more than 10 mass parts, since calcium sulfide has the effect | action which raises the pH of an eluate, since elution will increase more than the inhibitory effect of the elution by reduction | restoration, elution cannot be prevented. Accordingly, 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide are added to 100 parts by mass of calcium aluminate-based slag. A more desirable range for preventing elution is preferably 3.0 to 8.0 parts by mass.

As for the composition of the calcium aluminate slag, it is appropriate that the total content of CaO and Al ₂ O ₃ is 70% by mass or more, and CaO / Al ₂ O ₃ is 1.5 to 2.0.

As mentioned above, in order to stably control the elution of the mixed soil below the soil environmental standard while ensuring the strength of the soil-based solidified material, the soil-based solidified material mixed with calcium aluminate-based slag, gypsum and calcium sulfide. The blending ratio is 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide with respect to 100 parts by mass of calcium aluminate slag. The strength of the solidified body when water is added to the soil-based solidified material of the present invention to form a solidified body is determined by the combination of calcium aluminate slag and gypsum, and the influence of the mixing of calcium sulfide is small. Hydrates obtained by adding gypsum to calcium aluminate-based slag form ettringite, which is stronger than the compressive strength of the solidified solidified material of calcium-based aluminate slag when used alone as the solidified material. Increase. For the production of ettringite, it is desirable that 12CaO · 7Al ₂ O ₃ is mainly present as the mineral composition of slag. In order to constitute the mineral composition of 12CaO · 7Al ₂ O ₃ , the total content of CaO and Al ₂ O _{3 in} the slag is suitably 70% or more by mass%, desirably 80% or more. It is preferable. If it is less than 70%, the content of SiO ₂ or MgO increases and calcium silicate or the like is generated, so that the production of ettringite is reduced, which is not appropriate from the viewpoint of suppressing the blending of the solidifying material and ensuring the strength. Further, components of the slag mineral composition of 12CaO · 7Al ₂ O ₃ occurs subjectively is 1.5 to 2.0 is appropriate at a ratio of CaO / Al ₂ O _3, 1.5~1.7 Is more preferable. Therefore, the composition of the calcium aluminate slag was such that the total content of CaO and Al ₂ O ₃ was 70% or more, and CaO / Al ₂ O ₃ was 1.5 to 2.0.

  In the soil-based solidified body of the present invention, it is appropriate that 5 to 20 parts by mass of the total of calcium aluminate-based slag, gypsum and calcium sulfide is blended with respect to 100 parts by mass of soil. Hereinafter, the total of calcium aluminate slag, gypsum and calcium sulfide is also referred to as a solidifying material.

  A solidified material is mixed with soil such as pure sand soil to form an earth-based solidified body, and to solidify and pave, use the solidified material blended under the above conditions, and further solidify the soil to 100 parts by mass. It is preferable to mix at least 5 parts by mass of the material. When a large amount of a solidifying material is added, the strength increases, but not only is the pavement having a too high strength and less burden on the foot, but also increases the elution. Moreover, the cost of a solidification material will become high if the compounding of a solidification material is increased. Therefore, it is appropriate that the solidifying material is 20 parts by mass or less, and desirably it is in the range of 5 to 12 parts by mass.

  The present invention is an earth-based solidifying material characterized in that calcium aluminate-based slag, gypsum and calcium sulfide are mixed in the soil, and an earth-based solidifying material obtained by mixing an appropriate amount of the solidifying material in accordance with the characteristics of the soil. It can be used or mixed with calcium aluminate-based slag, gypsum and calcium sulfide in the soil to form a soil-based solidified material, added with water, leveled, and properly pressed and solidified for paving. When mixing soil-based solidification material and water, if there is a concrete mixer, it can be easily mixed uniformly with water. However, if there is no mixer, it is difficult to mix manually, so mixed soil-based solidification After the material is spread and leveled, water can be uniformly sprayed from the surface and water can be added, and then spread and paved.

  When paving a heavy object such as a vehicle, it is better to lay down a subgrade material such as crushed stone under the surface pavement. The thickness of the lower roadbed material and the thickness of the surface pavement material are determined according to the application. For example, in a sidewalk or the like, after a lower roadbed material is laid and hardened to a thickness of 50 to 100 mm, an earth-based solidified material is laid and hardened about 50 mm on the surface layer.

  The mixing ratio of soil and calcium aluminate-based slag, gypsum and calcium sulfide can be appropriately determined from the elution of the mixed soil-based solidified material and the road surface strength in consideration of the intended use and soil characteristics. When the strength of the road surface that does not burden the foot such as a sidewalk is sufficient, or when the road surface strength is required in a parking lot or the like, there is an appropriate strength depending on the application, so it is desirable to determine the composition according to the strength. In addition, since the quality varies depending on the production area of the soil, even if the same proportion of calcium aluminate slag, gypsum and calcium sulfide are mixed, the elution characteristics and strength differ. Therefore, it is necessary to conduct a blending test in advance and determine the blending of soil and calcium aluminate-based slag, gypsum and calcium sulfide and the amount of added water so as to meet appropriate elution suppression and strength.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to a following example.

  As the soil to be used for the soil-based solidifying material, among the sands generally used for parks, grounds, etc., soils that are alkaline and have a relatively high F elution amount were selected. As the solidifying material to be mixed with the soil, gypsum and calcium sulfide were mixed using calcium aluminate-based slag having various component compositions. The compressive strength and dissolution test results of the soil-based solidified material mixed with soil and solidified material were evaluated.

  The evaluation method of the compressive strength of the soil-based solidified material is that the soil-based solidified material obtained by mixing the soil and the solidified material is well kneaded, then 30% water is added and further kneaded, and in accordance with JIS A 1108 (Concrete compressive strength test method). Specimens were manufactured and uniaxial compressive strength was measured after curing for 7 days.

Using the specimen sample after measuring the compressive strength, a dissolution test was conducted according to the Environmental Agency Notification No. 46 method. As the components to be analyzed in the dissolution test, eight elements of Cd, Pb, Cr ⁶⁺ , As, Se, F, B, and Hg were confirmed. Among these, Cd, Cr ⁶⁺ , As, B, and Hg were not stably detected in the used soil and the solidified material mixed with the soil, so Pb, Se, and F were used as the survey elements.

[Example 1]
Table 1 shows the composition of the slag components used in the examples.

  The calcium aluminate slag (A) shown in Table 1 of the present invention was used as a solidified material, and the soil-based solidified material was evaluated by mixing the solidified material with true sand.

First, as a comparative example, a test specimen was manufactured by kneading only pure sand with water without using a solidifying material, and a compressive strength and a dissolution test were performed. The results are shown in Example Comparative Example 1 in Table 2. There is no strength at all of the specimens molded without compounding the solidifying material. In the elution test of the specimen, the pH was 9.6, indicating alkalinity, and the F elution amount was 0.6 mg / liter. In Example Comparative Example 2, only calcium aluminate-based slag was used as a solidifying material, and 10 parts by mass of the solidifying material was mixed and mixed with 100 parts by mass of sandy sand. The pressure strength was measured after curing for 7 days. Although a compressive strength of 3.4 N / mm ^{2 was} obtained, elution of F, Pb, and Se occurred beyond the soil environment standard. Moreover, in Example Comparative Example 3, a test specimen in which equal amounts of calcium aluminate slag and gypsum were mixed in a solidified material and mixed uniformly was used as a solidified material, and 10 parts by mass of the solidified material was blended with 100 parts by mass of sand. The strength was measured. The compressive strength was as high as 5.7 N / mm ^{2. In} the dissolution test results, the dissolution of F was suppressed below the soil environmental standard, but the dissolution of Pb and Se occurred beyond the soil environmental standard.

  In Invention Examples 1 to 3 in Table 2, 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide are blended with 100 parts by mass of calcium aluminate-based slag and mixed uniformly to obtain a solidified material. It was. Similarly to the comparative example, 10 parts by mass of a solidifying material was blended with 100 parts by mass of sand sand, and a test specimen was prepared and subjected to strength and dissolution tests. A sufficient compressive strength is obtained, and all of F, Pb, and Se satisfy the soil environmental standards in the dissolution test, and the superiority of the present invention is clear.

[Example 2]
As shown in Table 3, the components of the calcium aluminate slag were those of Invention Example 1 to Comparative Example 2 (A to G) in Table 1, and CaO and Al ₂ O ₃ components of the calcium aluminate slag. , And the compressive strength and dissolution test of the soil-based solidified material were conducted.

In Example Comparison 1, the slag type F in Table 1 was used. The content of Al ₂ O ₃ is small, the total amount of CaO and Al ₂ O ₃ is as small as 46.7%, and at the same time, CaO / Al ₂ O ₃ is as high as 2.6. The type G slag of Example Comparative 2 although the total amount of CaO and Al ₂ O ₃ is greater than 74% and 70%, lower the CaO / Al ₂ O ₃ is 1.1. The compressive strength of the test body (Example comparison 1 and 2 of Table 3) created from the soil type solidification material using these Table 1 comparative examples 1 and ² is as low as 2N / mm2 level cost.

Invention examples 1 to 5 in Table 1 in which the total content of CaO and Al ₂ O _{3 in} the calcium aluminate slag is 70% or more and CaO / Al ₂ O ₃ is 1.5 to 2.0 (A The specimens (Examples 1 to 5 of the present invention in Table 3) prepared by mixing the solidified material using ~ E) and mixed with soil have a compressive strength of 5 N / mm ² or more, and the superiority of the present invention is clear. . For the dissolution test, 100 parts by weight of calcium aluminate slag is mixed with 100 parts by weight of gypsum and 5 parts by weight of calcium sulfide, so that the dissolution of any element of F, Pb, and Se is below the soil environment standard. Can be suppressed.

[Example 3]
Table 4 shows examples of the present invention and comparative examples in which the composition of the solidifying material in the earth-based solidifying material was varied.

Using calcium aluminate slag (A) having the composition shown in Example 1 of Table 1, 100 parts by mass of gypsum and 5 parts by mass of calcium sulfide are added to 100 parts by mass of the calcium aluminate slag. 5 parts by mass (Invention Example 1 in Table 4) and 20 parts by mass (Invention Example 2 in Table 4) are mixed with 100 parts by mass of sandy sand, and the mixture is mixed and mixed with water. After that, a test specimen was manufactured. In Invention Examples 1 and 2 in Table 4, the compressive strength of the test specimen can be 3 N / mm ² or more by blending the blending amount of the solidifying material with 5 parts by mass or more with respect to 100 parts by mass of the sand. The dissolution test can be controlled without any problem below the soil environmental standards.

  In Example Comparative Example 1, when the blending amount of the solidifying material is less than 5 parts by mass with respect to 100 parts by mass of the true sand soil, elution can satisfy the soil environmental standards, but the compressive strength is low and the strength cannot be ensured. . Moreover, in Example Comparative Example 2, when the blending amount of the solidifying material exceeds 20 parts by mass with respect to 100 parts by mass of the true sandy soil, a high compressive strength can be secured, but the elution of F is increased by increasing the blending amount of the solidifying material. Increased to exceed soil environmental standards.

  By setting the blending ratio of the solidifying material in the range of 5 to 20 parts by mass with respect to 100 parts by mass of the true sand, the strength of the solidified body can be secured and the elution of the components can be stably suppressed.

Claims (3)

  Calcium aluminate-based slag, gypsum and calcium sulfide are blended in the soil, and 100 to 100 parts by mass of calcium aluminate-based slag is within a range of 50 to 150 parts by mass of gypsum and 2.5 to 10 parts by mass of calcium sulfide. An earth-based solidifying material characterized by being. The composition of the calcium aluminate-based slag is 70% by mass or more in total of the contents of CaO and Al ₂ O ₃ , and CaO / Al ₂ O ₃ is 1.5 to 2.0. Item 2. A solidified solid material according to item 1.   The earth-based solidified material according to claim 1 or 2, wherein 5 to 20 parts by mass of a total of calcium aluminate-based slag, gypsum and calcium sulfide is blended with respect to 100 parts by mass of soil.