JP2020094198A - Soil improvement material, and soil improvement method - Google Patents

Abstract

To provide a novel material capable of improving strength to clay-like soil high in moisture content, capable of suppressing elution of a harmful material even when the harmful material such as selenium or boron, and capable of being used for soil improvement.SOLUTION: The soil improvement material contains at least one burned product selected from a group consisting of a burned product of a following (A) component, a burned product of a following (B) component, or a mixture containing the (A) component and the (B) component. (A) component: at least one component selected from a group consisting of Ca(OH), CaCO, CaCl, and Ca(NO). (B) component: at least one component of Al(OH)and Al(SO).SELECTED DRAWING: Figure 1

Description

The present invention relates to a soil improvement material and a soil improvement method.

Soil having a high water content is viscous and its strength is reduced, so that the ground composed of such soil is soft. Therefore, in the civil engineering work, if the ground is soft like this, various problems occur. That is, it is difficult to run heavy machinery (decrease in trafficability), and when the soil collected from the ground is transported, it flows out of the container. Therefore, in the case of soft ground, first, a treatment for improving the soil quality is required for the soil of the ground.

As a method of improving the soil quality of soft ground, generally, there is a method of mixing so-called cement-based solidifying material with soil collected from the ground (Patent Document 1).

JP, 2014-162696, A

However, in the case of soil having a high water content, even if the cement-based solidifying material is mixed, the mixture has a problem that the strength is low and the viscosity is high.

Therefore, an object of the present invention is to provide, for example, a new material that can be used for soil improvement by improving the strength of clay-like soil having a high water content.

In order to achieve the above-mentioned object, the soil improvement material of the present invention is a fired product of the following component (A), a fired product of the following component (B), or a mixture containing the component (A) and the component (B). And at least one fired product selected from the group consisting of fired products of 1.
Component (A): at least one component selected from the group consisting of Ca(OH) ₂ , CaCO ₃ , CaCl ₂ , and Ca(NO ₃ ) ₂ Component (B): Al(OH) ₃ and Al ₂ ( SO ₄ ) ₃ at least one component

The soil improvement method of the present invention is characterized by including a mixing step of mixing the soil improvement material of the present invention with soil collected from the ground.

The improved soil of the present invention is characterized by including ground soil and the soil improvement material of the present invention.

The method for producing improved soil of the present invention includes a soil improvement step, and the soil improvement step is performed by the soil improvement method of the present invention.

The method for producing improved land of the present invention includes a land improvement step, and the land improvement step is performed by the soil improvement method of the present invention.

According to the soil improvement material of the present invention, for example, the soil collected from the ground, by mixing the soil improvement material, even if the water content of the soil is high, the soil, more manageable It can be modified into soil with excellent strength. Therefore, the present invention is extremely useful, for example, in soil improvement and ground improvement in civil engineering work.

3 is a photograph showing the appearance of a soil sample with a water content ratio of 40% in Example 1. 3 is a graph showing the strength of the mixed sample of Example 1. 3 is a graph showing the elution concentration of harmful substances in the mixed sample of Example 1. 5 is a photograph showing the appearance of a soil sample with a water content of 200% in Example 2.

In the soil improvement material of the present invention, the calcined product has a molar ratio of Ca to Al (Ca/Al) in the range of 0.5 to 15, for example.

In the soil improvement material of the present invention, for example, the fired product is a fired product of a mixture containing the component (A) and the component (B), and the component (A) is Ca(OH) ₂ and CaCO. ₃ ), and the component (B) is Al(OH) ₃ .

Soil improvement agent of the present invention, for example, as the fired _{product, CaO,} consisting _{Ca 12 Al 14 O 33, Ca} 5 Al 6 O 14, CaAl 4 O 33, Ca 12 Al 14 O 7, and CaAl ₂ O ₄ It comprises at least one crystalline compound selected from the group.

The soil improvement material of the present invention further includes the cement-based solidifying material, for example.

The soil improvement material of the present invention has, for example, an ion adsorption function.

In the soil improvement material of the present invention, for example, the ion is at least one ion selected from the group consisting of hexavalent chromium, selenium, arsenic, fluorine, and boron.

In the soil improvement method of the present invention, for example, a cement-based solidifying material is further mixed in the mixing step.

In the soil improvement method of the present invention, for example, the amount of the soil improvement agent added per 1 m ³ of the soil is 10 to 300 kg.

In the soil improvement method of the present invention, for example, the addition amount of the cement-based solidifying material per 1 m ^{3 of the} soil is 10 to 300 kg.

In the soil improvement method of the present invention, for example, the addition ratio of the soil improvement material and the cement-based solidifying material is in the range of 1:0.03 to 1:30.

In the soil improvement method of the present invention, for example, the mixture in the mixing step is not solidified by heating.

Embodiments of the present invention will be described below. The present invention is not limited to the embodiments below.

(Soil improvement material)
As described above, the soil improvement material of the present invention is a fired product of the following component (A), a fired product of the following component (B), or a fired product of a mixture containing the component (A) and the component (B). At least one fired product selected from the group consisting of:
Component (A): at least one component selected from the group consisting of Ca(OH) ₂ , CaCO ₃ , CaCl ₂ , and Ca(NO ₃ ) ₂ Component (B): Al(OH) ₃ and Al ₂ ( SO ₄ ) ₃ at least one component

According to the soil quality improving material of the present invention, the soil quality can be improved, for example, as described later. Further, by using the fired product together with the cement-based solidifying material, the soil quality can be improved more effectively. Specifically, according to the soil improvement material of the present invention, the strength of the soil after the treatment can be improved in the soil having a high water content ratio as compared with the case where only the cement-based solidifying material is added. Further, for example, the strength of the treated soil can be further improved by using the burned material and the cement-based solidifying material in combination. The soil improving material of the present invention is also referred to as a soil improving material because it can improve the soil quality of the ground. Further, the soil-improving material of the present invention can be used as a soil-improving auxiliary material for the cement-based solidifying material because it can efficiently improve the soil quality when used in combination with the cement-based solidifying material. Further, the soil improving material of the present invention can be said to be a water absorbing material for soil or a soil strength increasing material because of such effects.

The “improvement in strength” means that the strength of the soil is significantly improved as compared with the case where the soil improvement agent of the present invention is not added. The strength index is not particularly limited, and may be, for example, uniaxial compressive strength or cone index. The uniaxial compressive strength and Cone index can be measured, for example, by the methods described in Examples below.

The soil improvement material of the present invention may have an ion adsorption function, for example. Therefore, by using the soil improvement material of the present invention, for example, harmful substances contained in the soil, even for harmful substances such as hexavalent chromium contained in the cement-based solidifying material, these are adsorbed to the outside. Soil quality can also be improved by suppressing the elution of. Regarding the suppression of elution of the harmful substance, for example, a method of using a cement-based soil solidifying material or a Ca-based soil solidifying material containing cement as a main component as an ion adsorbent for immobilizing ions that are harmful substances is known. However, the types of harmful substances that can be suppressed from elution are limited depending on the type of the solidifying material used as the ion adsorbent. However, according to the soil improvement material of the present invention, it is possible to suppress elution by adsorption of a wide range of ionic substances such as hexavalent chromium, selenium, arsenic, fluorine, and boron known as the harmful substances. .. Therefore, the soil improvement material of the present invention can be referred to as, for example, an ion adsorbent or a harmful substance adsorbent. The form of the adsorbed harmful substance is not limited to ions.

The soil improvement material of the present invention is characterized in that it contains any of the above fired products, and other configurations are not limited at all. The soil improvement material of the present invention may include, for example, only the fired product, or may further include other components in addition to the fired product as long as the effects of the fired product are not impaired.

Hereinafter, the calcined product of the component (A) is a simple substance calcined product A, the calcined product of the component (B) is a simple substance calcined product B, and a mixture (AB) containing the component (A) and the component (B). The fired product is referred to as a mixed fired product AB. The soil-improving material of the present invention may include, as the fired product, only the single-fired product A or the single-fired product B alone, or may include the single-fired product A and the single-fired product B. Both may be included, or only the mixed fired product AB may be included, and the mixed fired product AB and the simple substance fired product A, the single substance fired product B, or the single substance fired product A and the single substance fired product. Both B may be included. Among them, the soil improving material of the present invention preferably contains, for example, the mixed fired product AB as a fired product.

In the soil improvement material of the present invention, the ratio of Ca and Al derived from the fired product is not particularly limited, and the molar ratio of Ca and Al (Ca/Al) is, for example, 0.5 to 15, 1 to 10. , 2 to 5. The molar ratio of Ca to Al (Ca/Al) is preferably 1 to 10 from the viewpoint that strength can be further improved, and the elution of harmful substances such as boron and hexavalent chromium can be suppressed more effectively. From the point, 2 to 5 is preferable.

In the soil improvement material of the present invention, the component (A) is preferably at least one of Ca(OH) ₂ and CaCO ₃ , and the component (B) is preferably Al(OH) ₃ . Further, in the soil improvement material of the present invention, the fired product is preferably the mixed fired product AB, and in this case, for example, at least one of the component (A) of Ca(OH) ₂ and CaCO ₃ and Al( A fired product AB of the mixture (AB) containing (OH) _{3 and} the component (B) is preferable.

Examples of the simple substance fired product A include crystalline compounds such as CaO. When the soil improvement material of the present invention contains the simple substance fired product A, for example, the type may be one type or two or more types. When the soil improvement material of the present invention contains the simple substance fired product B, the type thereof may be one type or two or more types.

Examples of the mixed calcined material AB include crystalline compounds such as Ca ₁₂ Al ₁₄ O ₃₃ , Ca ₅ Al ₆ O ₁₄ , CaAl ₄ O ₃₃ , Ca ₁₂ Al ₁₄ O ₇ , and CaAl ₂ O ₄ . When the soil improvement material of the present invention contains the mixed fired product AB, for example, the type thereof may be one type or two or more types. The crystalline compound is produced by a chemical reaction by firing a mixture of the component (A) and the component (B). In the mixed fired product C, the composition of the crystalline compound can be changed depending on, for example, the ratio (molar ratio) of the component (A) and the component (B) used, the firing temperature, and the like.

The baked product A, the baked product B, and the mixed baked product can be produced, for example, by baking the component (A), the component (B), or the mixture (AB). The firing temperature is not particularly limited, and the lower limit thereof is, for example, 600° C. or higher and 800° C. or higher, and the upper limit thereof is, for example, 1200° C. or lower and 1000° C. or lower.

As described above, the soil improvement material of the present invention may contain other components, and examples of the other components include adsorbents that adsorb ions such as heavy metals.

Further, the soil improvement material of the present invention may further include a cement-based solidifying material, as described above. In the soil quality improvement method of the present invention described below, for example, the soil quality can be effectively improved by using the fired product and the cement-based solidifying material.

In the present invention, the cement-based solidifying material is not particularly limited, and is not limited to, for example, a known cement-based solidifying material, and a cement-based solidifying material after the application of the present application can also be used. The cement solidifying material, as a main component, for example, silicate tricalcium 3CaO · SiO ₂ (Alit), dicalcium silicate 2CaO · SiO ₂ (Berit), tricalcium aluminate 3CaO · _Al 2 _{O 3,} iron aluminate tetracalcium calcium _{4CaO · Al 2 O 3 · Fe} 2 O 3 ( celite), and a gypsum CaSO ₄ · 2H ₂ O or the like. The cement-based solidifying material is, for example, as a typical one, a solidifying material for general soft soil corresponding to the soil to be improved, and a general-purpose solidifying material such as a solidifying material for special soil, a solidifying material for high organic soil, a use environment. A dust-suppression type solidifying material and the like corresponding to the above are listed.

The soil improvement material of the present invention can be used in the soil improvement method of the present invention described later. Further, for example, the fired product and the cement-based solidifying material may be used together and used in the soil improvement method. When the soil improvement material of the present invention contains the fired product and the cement-based solidifying material, for example, with respect to the soil collected from the ground, the cement-based solidifying material and the fired material are mixed separately. Or may be mixed at the same time. Therefore, when the soil improvement material of the present invention contains the fired product and the cement-based solidifying material, for example, the cement-based solidifying material and the fired product may be in the form of separate kits, It may be in a mixed state in which the cement-based solidifying material and the fired product are mixed.

Soil improvement material of the present invention, when containing the fired product and the cement-based solidifying material, the content ratio of the cement-based solidifying material and the soil-improving material is not particularly limited, for example, of the present invention described below. The usage rate in the soil improvement method can be applied.

(Soil improvement method)
The soil improvement method of the present invention is characterized by including a mixing step of mixing the soil improvement material of the present invention with the soil of the ground as described above. The soil improvement method of the present invention is characterized by using the soil improvement material of the present invention (specifically, the fired product), and other steps and conditions are not limited at all. Regarding the soil improving material, the description of the soil improving material of the present invention can be applied. The soil improvement method of the present invention is also referred to as a soil improvement method because, for example, the soil quality of the soil can be improved. Further, the soil improvement method of the present invention, for example, by combining the fired product of the soil improvement material and the cement-based solidifying material, since it is possible to further efficiently improve the soil quality, soil improvement for the cement-based solidifying material It can also be called an auxiliary method. Regarding the cement-based solidifying material, the description of the soil improving material of the present invention can be applied. Further, the soil improvement method of the present invention can be said to be a water absorption method for soil or a soil strength increasing method, for example, from such effects.

As described above, in the mixing step, in addition to the soil improvement material of the present invention, for example, the cement-based solidifying material may be further mixed. The soil improvement material of the present invention, in addition to the fired product, if the cement-based solidifying material, the mixing step, for example, separately from the soil-improving material, it is necessary to prepare the cement-based solidifying material. If the soil improvement material of the present invention does not include the cement-based solidifying material, the cement-based solidifying material may be prepared separately from the soil-based solidifying material.

In the mixing step, for example, the soil of the ground may be dug up and treated on the spot, or the soil of the ground may be dug up, the soil may be moved to another place by a shovel or the like, and the treatment may be performed at the moved place. May be given.

The amount of the burned material added to the soil improvement material to the soil is not particularly limited. The lower limit of the amount of the burned material added to the soil improvement material per 1 m ³ of soil is, for example, 10 kg, 20 kg, or 50 kg, and the upper limit thereof is, for example, 200 kg or 300 kg, and the range is, for example. , 10 to 300 kg, 50 to 200 kg and the like. Here, the soil unit “m ³ ”can be represented, for example, by the volume of the ground that is the source of the soil to be treated. As a specific example, 1 m ^{3 of} soil is obtained by excavating the ground 1 m ^3. Means soil. The volume of the ground can be converted into, for example, the weight of soil, and assuming that the soil of 1 m ³ of soil has a water content ratio of 40% and a density of 1 to 2.1, for example, the weight of soil containing water is 1400 to 2940 kg. Is.

The soil improvement material of the present invention is suitable for soil improvement of soil having a relatively high water content ratio, and the soil improvement method of the present invention is preferably applied to soil having such a water content ratio, for example. The water content ratio is, for example, the ratio (%) of water when the weight of the soil to be treated is 100%, excluding the weight of water. As a specific example, the weight of the soil to be treated (including moisture) is 140 kg. If the weight excluding water is 100 kg, the water content ratio (%) can be expressed as 100×(140-100)/100=40%. In the present invention, the water content ratio of the soil to be treated is not particularly limited, and examples thereof include 30 to 200%, 30 to 60%, 40 to 50% and the like. In the mixing step, if the amount of the soil improvement agent added to the soil is within the above range, the soil having the water content ratio can be effectively improved.

The soil quality improvement method of the present invention can also improve the soil quality of mud-like soil (mud), for example. The mud is a soil classification generally classified as construction sludge, mud, etc. in the field of civil engineering business, for example. The water content of the mud is not particularly limited and is, for example, 80% or more, and its constituent component is, for example, mainly composed of fine particles. Such soil is carried out, for example, by excavation work or dredging work. Specific examples of the mud-like soil include reservoirs, rivers, and bottom mud in coastal areas. Note that the muddy state may be classified by strength, and in this case, for example, "a state where a standard specification dump truck cannot be stacked and a person cannot walk on it, in terms of the indicator of the strength of the soil, corn index is approximately 200kN / m ² or less, or uniaxial compressive strength generally refers to the soil of 50kN / m ² or less "(reference: aptitude processing of waste arising from construction work About (Environment Abandoned Product No. 276, June 2001).

Further, the amount of the burned material added to the soil may be appropriately set depending on, for example, the water content ratio of the soil. When the water content of the soil to be treated is 40%, the lower limit of the addition amount of the fired product in the soil improvement material per 1 m ³ of the soil is, for example, 10 kg, 20 kg, 50 kg, and the upper limit thereof is For example, it is 200 kg, 300 kg, 500 kg, and the range is, for example, 10 to 300 kg, 50 to 200 kg and the like. When the water content of the soil to be treated is 200%, the lower limit of the amount of the burned material added to the soil improvement material per 1 m ³ of the soil is, for example, 50 kg, 100 kg, 150 kg, and the upper limit thereof is: It is not particularly limited and is, for example, 200 kg, 300 kg, 500 kg, and the range is, for example, 50 to 500 kg, 100 to 300 kg, 150 to 200 kg and the like. Then, for example, when the water content ratio of 40% is used as a reference, and when the water content ratio of the soil to be treated is relatively high, the addition amount of the fired product is relatively increased so that the water content ratio of the soil to be treated is relatively high. When the amount is low, the addition amount of the fired product may be relatively reduced. The amount of the burned material added can be appropriately set by, for example, confirming the water content ratio of the soil to be treated in advance and calculating it based on the conditions as described above.

Further, the amount of the fired product added to the soil may be appropriately set depending on, for example, the intended strength of the final mixture.

When the cement-based solidifying material is further mixed in the mixing step, the amount of the cement-based solidifying material added to the soil is not particularly limited. The lower limit of the amount of the cement-based solidifying agent added per 1 m ^{3 of the} soil is, for example, 10 kg, 20 kg, and 50 kg, and the upper limit thereof is, for example, 100 kg, 200 kg, and 300 kg, and the range is, for example, 10 ~300 kg, 50-200 kg, etc.

The addition ratio of the soil conditioner and the cement-based solidifying agent added to the soil is, for example, 1:0.25 to 1:1 and 1:0.03 to 1:30.

The order of mixing the cement-based solidifying material and the fired product with respect to the soil is not particularly limited, for example, both may be mixed at the same time, or after mixing the cement-based solidifying material, the fired product is mixed. Alternatively, the cement-based solidifying material may be mixed after mixing the burned material.

The method of mixing the soil with the cement-based solidifying material and the fired product is not particularly limited, and for example, in the field, mixing with a heavy machine such as a hydraulic excavator or mixing with a mobile plant can be performed.

In the soil improving method of the present invention, in the mixing step, it is only necessary to mix the soil and the fired material of the soil improving material, for example, the mixture in the mixing step is not solidified by heating. Is preferred. The solidification treatment depends on the type of the cement-based solidifying material, for example, when the cement-based solidifying material is mixed, but usually heat treatment can be exemplified. Examples of the heat treatment include steam curing treatment with high-pressure steam or low-pressure steam, and the steam curing treatment is performed at, for example, 60° C. or higher. In the civil engineering work, for example, the soil collected from the ground may be moved to another place for reuse, or after the desired work is completed, the soil may be returned to the original ground for earthmoving. In such a case, if the soil mixture collected from the ground is subjected to heat treatment to be completely solidified into concrete, reuse becomes difficult. Further, for example, even when it is desired to improve the strength of the ground only during work, if it is made concrete, it cannot be returned to the soil ground. According to the present invention, for example, only by performing the mixing step, it is possible to improve the strength without solidification (concreteization) by heating, so that the problem due to solidification can be solved.

According to the soil improvement method of the present invention, as described above, for example, harmful substances contained in soil, and harmful substances contained in the cement-based solidifying material are adsorbed to the soil improving material and are insolubilized, It is understood that the elution of the harmful substances is suppressed. However, this estimation does not limit the present invention.

According to the soil improvement method of the present invention, for example, by mixing the soil improvement agent of the present invention with the soil of the ground, the soil quality can be improved, and the soil can be improved to have strength excellent in handleability.

(Improved soil)
As described above, the improved soil of the present invention includes the soil of the ground and the soil improvement material of the present invention. The improved soil of the present invention is characterized by including the soil improving material of the present invention, and other conditions and configurations are not particularly limited. In the improved soil of the present invention, the description of the soil improvement material and the soil improvement method of the present invention can be applied to the soil improvement material. The improved soil of the present invention can be produced, for example, by the method for producing the improved soil of the present invention described below.

The improved soil of the present invention includes the soil improvement material of the present invention, and thus has improved soil quality. Specifically, the soil strength is improved, and therefore, the improved soil is, for example, excellent in handleability. Therefore, the improved soil of the present invention can be used, for example, as a foundation ground material for construction work, an embankment embankment material, a roadbed, and a roadbed material.

(Method for producing improved soil)
As described above, the method for producing improved soil of the present invention is characterized by including the soil improvement step, and the soil improvement step is carried out by the soil improvement method of the present invention. The soil improvement method of the present invention is characterized in that the soil is improved by the soil improvement method of the present invention, that is, the soil of the ground is mixed with the soil improvement material of the present invention, and other steps and conditions. Is not particularly limited. According to the method for producing improved soil of the present invention, since the soil improvement material of the present invention is mixed with the soil of the ground, it is possible to produce improved soil having improved soil quality. The description of the soil improvement material and soil improvement method of the present invention can be applied to the method for producing improved soil of the present invention.

The amount of the soil improvement agent of the present invention to be added and the mixing method in the soil improvement step are not particularly limited and can be appropriately set according to the soil volume and water content of the soil to be mixed. Regarding the addition amount and mixing method of the soil quality improving material in the method for producing improved soil of the present invention, the description of the mixing step in the soil quality improving method of the present invention can be applied.

The improved soil is produced by the method for producing improved soil of the present invention, and other conditions are not particularly limited. The improved soil includes, for example, the soil improvement material of the present invention.

The improved soil produced by the improved soil production method of the present invention has improved soil quality and improved strength. Therefore, the improved soil can be used, for example, as a foundation ground material for construction work, a bank embankment material, a roadbed, and a roadbed material.

(Method of producing improved land)
As described above, the method for producing improved land of the present invention includes a land improvement step, and the land improvement step is performed by the soil improvement method of the present invention. The land improvement method of the present invention is characterized in that the soil is improved by the soil improvement method of the present invention, that is, the soil of the ground is mixed with the soil improvement material of the present invention. Other steps and conditions Is not particularly limited. According to the method for producing improved land of the present invention, the soil improving material of the present invention is mixed with the soil of the ground, so that the improved soil containing the improved soil can be produced. The improved land is, for example, a land containing the improved soil in soil and is also referred to as improved soil. Regarding the method for producing improved land of the present invention, the description of the soil improvement material, soil improvement method and improved soil production method of the present invention can be applied.

The addition amount and mixing method of the soil improvement material of the present invention in the land improvement step are not particularly limited, and can be appropriately set according to the soil volume and water content of the ground to be mixed. Regarding the addition amount and the mixing method of the soil improvement material in the method for producing improved land of the present invention, the description of the mixing step in the soil improvement method of the present invention can be applied.

The improved land is produced by the method for producing improved land of the present invention, and other conditions are not particularly limited. The improved land includes, for example, the improved soil of the present invention and/or the soil improvement material of the present invention.

The improved land produced by the improved land producing method of the present invention has improved soil quality and improved strength. Therefore, the improved land can be used, for example, as a site for civil engineering work, a bank, a road, or the like.

[Example 1]
The soil was treated with the soil improvement material of the present invention, and the soil quality was confirmed.

(1) Preparation of Soil Conditioning Material As described below, a fired product was prepared from the mixture (AB) of the component (A) and the component (B) and used as a soil improving agent. Specifically, a mixture of CaCO ₃ and Al(OH) ₃ with a Ca/Al molar ratio=5 was fired at 1000° C. to obtain a fired product.

(2) Soil sample The soil in the landfill was drilled and soil was collected from multiple points. Specifically, boring was used for drilling, and columnar soil was collected. Then, a plurality of cylindrical soils were uniformly mixed except for pebbles and the like. The mixed soil had a mass of 4.8 kg (including water), a density of 1190 kg (including water)/m ³ , and a water content ratio of 33.3%. The mixed soil was divided into 500 g each, and water was added to each of them, and four of them were prepared to be a soil sample 1 having a water content ratio of 40%, and four of which were soil samples 2 having a water content ratio of 50%.

(3) Soil improvement treatment JIS standard blast furnace cement class B was used as the cement-based solidifying material. With respect to each of the soil sample 1 (water content ratio 40%) and the soil sample 2 (water content ratio 50%), the mass of the natural water content ratio (40%, 50%) per 1 m ³ of wet soil was 50 kg/m ³ . So that the cement-based solidifying material is added and thoroughly mixed by hand-kneading, and then the soil-improving material is added so that a predetermined amount (0, 50, 100, 200 kg/m ³ ) is obtained. , And mixed well in the same manner.

(4) Confirmation of soil quality (4-1) Appearance For each of the soil sample 1 and the soil sample 2, soil improvement treatment was performed as shown in (3), and the appearance was confirmed. Specifically, the appearance was confirmed before the addition of the cement-based solidifying material, after the addition of the cement-based solidifying material, and after the addition of both the cement-based solidifying material and the soil improvement material. The results are shown in FIG. FIG. 1 is a photograph showing the appearance of the sample 2 (water content ratio 50%).

As shown in FIG. 1, the following results were obtained for the sample 2 (water content ratio 50%). First, as shown in FIG. 1(A), since the untreated soil sample 2 had a high water content ratio, the soil itself could not retain water, and was very loose and sticky and viscous soft soil. Then, as shown in FIG. 1(B), the mixed sample obtained by mixing the untreated soil sample 2 with the cement-based solidifying material showed a slight water-like property, but showed a loose and sticky viscosity. It was The soil in such a state is barely modified so that the soil can retain water, but it is difficult to use it for civil engineering work such as material transportation and pile-up. On the other hand, after mixing the cement-based solidifying material, the mixed sample to which the burned material that is the soil-improving material was further added was, as shown in FIG. 1 (C1) and (C2), It has lost its porosity and has been decomposed into lumps. The soil in such a state can be sufficiently used for the civil engineering work described above. Although not shown, similar behavior could be confirmed for the sample 1 (water content ratio 40%).

(4-2) Strength A strength test was performed on each of the samples of (4-1) as described below.

For the soil sample 1 (water content ratio 40%), the cement-based solidifying material (50 kg/m ³ ) was mixed and the burned material (soil conditioner) was not added to the mixed sample (40-0), the cement-based solidifying material. Material (50 kg/m ³ ) and the fired product (50 kg/m ³ ) mixed sample (40-50), the cement-based solidifying material (50 kg/m ³ ) and the fired product (100 kg/m ³ ). A mixed sample (40-100), a mixed sample (40-200) in which the cement-based solidifying material (50 kg/m ³ ) and the fired product (200 kg/m ³ ) were mixed were used. For the soil sample 2 (water content ratio 50%), the cement-based solidifying material (50-0) mixed with the cement-based solidifying material (50 kg/m ³ ) and the cement-based solidifying material (50 kg) was added. /M ³ ) and the burned material (50 kg/m ³ ) mixed sample (50-50), the cement-based solidifying material (50 kg/m ³ ) and the burned material (100 kg/m ³ ) mixed. A mixed sample (50-200) in which a sample (50-100), the cement-based solidifying material (50 kg/m ³ ) and the fired product (200 kg/m ³ ) were mixed was used.

Each of the samples was filled in a mold (molding container) and processed into a cylindrical test body having a diameter of 5 cm and a height of 10 cm. Specifically, it carried out as follows.

(Production method)
The sample was tamped on the cylindrical mold using a 1.5 kg rammer and a collar to prepare the cylindrical test body. When the test body was in close contact with the mold and was unlikely to peel off, a cylindrical polyethylene sheet was previously attached to the inner wall of the mold, and then the sample was tamped. As for the tamping method, the rammer was allowed to fall freely from a height of 20 cm and rammed in three layers. The number of times of compaction was 12 times for each layer. The amount of the sample added to the mold was adjusted so that the amount of the sample compacted per layer was about ⅓ of the height of the test body after the compaction. Moreover, the end surface of each layer was notched with a spatula or the like to ensure close contact with the layer above it. After compacting 3 layers, the collar was removed and excess soil on top of the mold was carefully scraped off with a straight edge. Holes formed on the surface of the test body due to sand grains and the like were filled with fine particles of the sample, and finished so as to have the same height as the upper surface of the mold. The production of the test body was completed as soon as possible.

(Curing method)
The prepared test body was covered with a thin polyethylene film on its upper surface and tightly bound with a rubber band to prevent the surface from drying, and was allowed to stand and cure until the next day. After one day of material age, the test body was taken out from the mold and its wet density was measured. Then, it was cured by sealing so as to prevent water evaporation. In addition, when the strength of the test body was low and it was difficult to remove the mold from the mold after 1 day of age, it was released from the mold after the strength reached a level capable of releasing the mold. The test body was sealed and cured to a predetermined material age in a thermo-hygrostat at a temperature of 20±3° C. and a humidity of 95% or more or under conditions similar thereto. The standard curing period of the test body was 7 days after the preparation of the test body. In addition, if necessary, it was arbitrarily set to 3 days, 28 days, or the like.

The columnar specimen was cured by leaving it to stand for 7 days (age 7 days) by the above-mentioned method, and then a compressive strength test was conducted. The compressive strength test was based on JIS A1108, and the compressive strength (N/mm ² ) was measured using a compressive strength tester (ABM200S, manufactured by JT Toshi Co., Ltd.).

The results are shown in FIG. FIG. 2 is a graph showing the compressive strength of the cylindrical test body of each mixed sample, and the vertical axis represents the compressive strength (N/mm ² ). As shown in FIG. 2, for sample 1 (water content 40%), only the cement-based solidifying material was added and compared with the mixed sample (40-0) to which the burned material (soil conditioner) was not added. The mixed sample (40-50) obtained by mixing the fired product (soil conditioner) showed remarkably high compressive strength. Similarly, for sample 2 (water content ratio 50%), as compared with the mixed sample (50-0) in which only the cement-based solidifying material was added and the burned material (soil conditioner) was not added, The mixed sample (50-50) obtained by mixing the fired product (soil conditioner) showed remarkably high compressive strength.

The cement-based solidifying material is usually solidified (concreteized) by heat curing to improve strength, but in this embodiment, heat curing is not performed. For this reason, the mixed samples (40-0) and (50-0) to which only the cement-based solidifying material was added had low strength, but each of the mixed samples (soil conditioner) was further mixed. As described above, each of the mixed samples exhibited significantly higher strength than the mixed samples (40-0) and (50-0) to which the baked product was not added. It is presumed that, as a result of the fired product (soil conditioner) absorbing water in the soil, it affects the hardening of the cementitious solidifying material, resulting in an increase in strength. This assumption does not limit the present invention.

(4-3) Elution prevention Using the columnar specimen of each mixed sample obtained in the above (4-2) at 7 days old, the amount of the substance eluted from the columnar specimen and the columnar The content (remaining amount) of the substance in the test body was confirmed.

The elution amount was measured as follows. That is, each of the cylindrical test bodies was pulverized and sieved to obtain a pulverized product having a particle size of 2 mm or less. 100 g of the pulverized product was suspended in 1 L of pure water, shaken for 6 hours, and then filtered through a filter paper (membrane filter having a pore size of 0.45 μm). Then, the concentrations of hexavalent chromium, selenium, arsenic, fluorine, and boron in the obtained filtrate were measured. Specifically, the concentration of hexavalent chromium was measured by a diphenylcarbazide absorptiometry (Spectrophotometer U-2900, manufactured by Hitachi, Ltd.), and ICP mass spectrometry (ICP-MS 7700 Series, Agilent Technologies, Inc.) was used. Selenium, arsenic, and boron concentrations were measured, and the fluorine concentration was measured by a flow analysis method (autoanalyzer SYNCA FCP, manufactured by BL TEC Co., Ltd.).

The results are shown in FIG. FIG. 3 is a graph showing the elution amount of a substance using the cylindrical test body of each mixed sample. In each graph, the vertical axis represents the concentration of each substance, the horizontal axis represents the amount of the soil improvement material (the burned material) in the mixed sample, and ◆ represents the soil sample 1 (water content ratio 40%). Is the result of the mixed sample containing, and ▪ is the result of the mixed sample containing the soil sample 2 (water content 50%). In addition, in each graph, the broken line with a low value indicates the lower limit of quantification. In FIG. 3, (A) is the result of hexavalent chromium, (B) is the result of selenium, (C) is the result of arsenic, (D) is the result of fluorine, (E) is the result of boron. In addition, in the graph, where only the plot of ■ is visible, the plot of ◆ is also plotted at the same position.

First, hexavalent chromium will be described. As for the soil sample (◆) having a water content ratio of 40%, as shown in the graph of FIG. 3(A), the soil improvement was compared with the mixed sample (40-0) to which the soil improvement agent was not added. It was confirmed that the concentration of the eluted hexavalent chromium decreased in each of the mixed samples to which the material was added. Further, the elution concentration of the hexavalent chromium decreased with an increase in the mixing amount of the soil improvement material, and decreased to the lower limit of quantification at the mixing amount of 200 kg/m ³ . Here, also for the water content ratio of 50% soil sample (■), confirmed similar decrease elution concentration in the mixing amount of 50 kg / m ^3, was reduced to quantitation limit.

Next, selenium will be described. As for the soil sample (◆) having a water content ratio of 40%, as shown in the graph of FIG. 3(B), the soil improvement was compared with the mixed sample (40-0) to which the soil improvement agent was not added. It was confirmed that the concentration of eluted selenium decreased in each of the mixed samples to which the material was added. Further, the elution concentration of the selenium decreased with an increase in the mixing amount of the soil improvement material, and decreased to the lower limit of quantification at the mixing amount of 200 kg/m ³ . In the soil sample (■) with a water content of 50%, a similar decrease in the elution concentration could be confirmed, and at the mixing amount of 200 kg/m ³ , it decreased to the lower limit of quantification.

Next, arsenic will be described. As shown in the graph of FIG. 3(C), the soil sample (♦) having a water content of 40% was compared with the mixed sample (40-0) to which the soil improving agent was not added, to improve the soil quality. In each of the mixed samples added with wood, the concentration of eluted arsenic was remarkably reduced. In addition, the elution concentration of the arsenic decreased with an increase in the mixing amount of the soil improvement material, and decreased to the lower limit of quantification at the mixing amount of 100 kg/m ³ . Here, also for the water content ratio of 50% soil sample (■), confirmed similar decrease elution concentration in the mixing amount of 100 kg / m ^3, was reduced to quantitation limit.

Next, fluorine will be described. As shown in the graph of FIG. 3(D), the soil sample (♦) having a water content of 40% was compared with the mixed sample (40-0) to which the soil improving agent was not added, to improve the soil quality. In each of the mixed samples to which the material was added, the concentration of eluted fluorine was significantly reduced. Further, the elution concentration of the fluorine decreased as the amount of the soil improvement agent mixed increased. In addition, the soil sample (■) having a water content ratio of 50% was similarly confirmed to have a lower elution concentration.

Next, boron will be described. As for the soil sample (◆) having a water content ratio of 40%, as shown in the graph of FIG. 3(E), the soil improvement was compared with the mixed sample (40-0) to which the soil improvement agent was not added. It was confirmed that the concentration of eluted selenium decreased in each of the mixed samples to which the material was added. Further, the elution concentration of the boron decreased with an increase in the mixing amount of the soil improvement material, and decreased to the lower limit of quantification at the mixing amount of 100 kg/m ³ . Here, also for the water content ratio of 50% soil sample (■), confirmed similar decrease elution concentration in the mixing amount of 100 kg / m ^3, was reduced to quantitation limit.

As described above, it was found that the use of the soil improvement agent can suppress the elution of any of the major harmful substances, hexavalent chromium, selenium, arsenic, fluorine, and boron. In order to prevent elution of various harmful substances, adsorbents and the like suitable for each harmful substance are usually selected, but the soil improvement material of the present invention has a broad elution prevention function for all of these. Can play.

[Example 2]
Using the soil improvement material of the present invention, mud having a water content of 200% was treated and the soil quality was confirmed.

First, water was added to clay having a water content of 36.8% to prepare a soil sample (mud) having a water content of 200%. Then, the use soil improvement agent (the fired product), as in Example 2-1, the mass relative to the soil sample 1 m ³ is such that a 100 kg, the fired product per volume 500ml of soil sample was added 50 g, hand mixing And mixed well. In addition, as Example 2-2, 50 g of the fired product per 500 ml of the volume of the soil sample, and the cement-based solidifying material used in Example 1 so that the mass of the soil sample of 1 m ³ was 100 kg, respectively. 50 g was added and mixed thoroughly by hand. In Comparative Example 2, 50 g of the cement-based solidifying material was added per 500 ml of the volume of the soil sample so that the mass of the soil sample of 1 m ³ was 100 kg without adding the burned material, and the mixture was sufficiently mixed by hand. ..

After mixing each sample, it was filled into a cylindrical container having a diameter of 5 cm and a height of 10 cm without any time, and a Yamanaka soil hardness meter (standard type, manufactured by Fujiwara Manufacturing Co., Ltd.) was used to measure the strength of the sample (cone. The index) was measured. The measurement was performed according to the instruction manual of the Yamanaka soil hardness meter.

The results are shown in Table 1 below. In addition, FIGS. 4A to 4D show appearances of untreated soil samples (water content ratio 200%), Comparative Example 2, Example 2-1, and Example 2-2.

As shown in Table 1 and FIGS. 4A to 4D, the untreated soil sample had a liquid appearance and a cone index of 0 kN/m ² . Also, in Comparative Example 2 in which only the cement-based solidifying material was added, the appearance was liquid and the cone index was 0 kN/m ² , and the strength was not exhibited. On the other hand, in Example 2-1 to which the soil improving material of the present invention (the fired product) was added, the appearance became plastic, and the cone index was 200 kN/m ² , and the strength was improved. In addition, in Example 2-2 in which a cement-based solidifying material was added in addition to the soil improvement material of the present invention, the appearance became plastic and the cone index was 250 kN/m ² , and the strength was further improved. ..

As described above, the soil sample of Comparative Example 2 in which only the untreated mud having a water content of 200% and the cement-based solidifying material were mixed had a cone index of 200 kN/m ² or less, which could not be piled up on the dump truck, and A person cannot walk on it. On the other hand, since the soil samples of Example 2-1 and Example 2-2 in which the soil improvement material of the present invention is mixed have a cone index of 200 kN/m ² or more, for example, they are piled on a dump truck, People can walk on it. As described above, according to the soil improvement material of the present invention, it was found that even the soil having a high water content ratio of 200% can improve the soil property and can be modified into the soil having the strength excellent in handleability. ..

The strength of the cement-based solidifying material is improved by reacting water in soil with cement to solidify. In this Example, since the measurement was carried out without delay after mixing, it is considered that in Comparative Example 2, the solidification reaction did not proceed and the strength was not exhibited. On the other hand, the soil improvement material of the present invention improved the strength of soil immediately after mixing. Further, the strength was further improved by using the soil improvement material of the present invention and the cement-based solidifying material in combination. This is because the fired product (soil conditioner) developed strength immediately after mixing as a result of absorbing water in the soil, and, like Example 1, also affected the hardening of the cementitious solidifying material. It is speculated that it was given. This assumption does not limit the present invention.

Although the present invention has been described with reference to the exemplary embodiments and examples, the present invention is not limited to the above-described exemplary embodiments and examples. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2018-228407 for which it applied on December 5, 2018, and takes in those the indications of all here.

According to the present invention, for example, in the mixing of the soil and the cement-based solidifying material collected from the ground, by using the soil improvement material together, even if the water content of the soil is high, the soil , And can be modified into a soil with excellent handleability and strength. Furthermore, according to the soil improvement material of the present invention, for example, in the soil or the like, even when harmful substances such as selenium and boron are contained, these are adsorbed and the harmful substances from the soil to the outside are removed. Elution can also be suppressed. Therefore, the present invention is extremely useful, for example, in soil improvement and ground improvement in civil engineering work.

Claims (16)

At least one fired product selected from the group consisting of a fired product of the following component (A), a fired product of the following component (B), or a fired product of a mixture containing the following components (A) and (B). Soil improvement material characterized by containing:
(A) component: at least one component selected from the group consisting of Ca(OH) ₂ , CaCO ₃ , CaCl ₂ , and Ca(NO ₃ ) ₂ ;
Component (B): At least one component of Al(OH) ₃ and Al ₂ (SO ₄ ) ₃ . The soil improvement material according to claim 1, wherein the calcined product has a molar ratio of Ca to Al (Ca/Al) of 0.5 to 15. The fired product is a fired product of a mixture containing the component (A) and the component (B),
The component (A) is at least one of Ca(OH) ₂ and CaCO ₃ .
The soil improvement material according to claim 1 or 2, wherein the component (B) is Al(OH) ₃ . The calcined product is at least one crystalline material selected from the group consisting of CaO, Ca ₁₂ Al ₁₄ O ₃₃ , Ca ₅ Al ₆ O ₁₄ , CaAl ₄ O ₃₃ , Ca ₁₂ Al ₁₄ O ₇ and CaAl ₂ O ₄ . The soil improvement material according to any one of claims 1 to 3, comprising a compound. Furthermore, the soil improvement material according to any one of claims 1 to 4, further comprising a cement-based solidifying material. The soil improvement material according to any one of claims 1 to 5, which has an ion adsorption function. The soil improvement material according to claim 6, wherein the ion is at least one ion selected from the group consisting of hexavalent chromium, selenium, arsenic, fluorine, and boron. A soil improvement method comprising a mixing step of mixing the soil improvement material according to any one of claims 1 to 7 with the soil of the ground. The soil improvement method according to claim 8, wherein the amount of the fired product added to the soil improvement material per 1 m ³ of the soil is 10 to 300 kg. The soil improvement method according to claim 8 or 9, further comprising mixing a cement-based solidifying material in the mixing step. The soil improvement method according to claim 10, wherein an addition amount of the cement-based solidifying material per 1 m ³ of the soil is 10 to 300 kg. The soil improvement method according to any one of claims 10 and 11, wherein an addition weight ratio of the fired product and the cement-based solidifying material is in a range of 1:0.03 to 1:30. The soil improvement method according to any one of claims 8 to 12, wherein the mixture in the mixing step is not solidified by heating. Improved soil comprising soil of the ground and the soil improvement material according to any one of claims 1 to 7. A method for producing improved soil, comprising a soil improvement step, wherein the soil improvement step is carried out by the soil improvement method according to any one of claims 8 to 13. A method for producing improved land, comprising a land improvement step, wherein the land improvement step is carried out by the soil improvement method according to any one of claims 8 to 13.