JP-2026075382-A - Soil modification materials, soil modification methods

Abstract

[Problem] To provide a soil modifier that can sufficiently solidify the target soil even if there is variation in its properties. [Solution] This is a soil modifier containing magnesium oxide and diatomaceous earth. The diatomaceous earth content is 20 to 200 parts by weight per 100 parts by weight of magnesium oxide. Since diatomaceous earth is rich in amorphous silica, adding it to the target soil allows the solidification effect of magnesium oxide to be fully exerted. [Selection Diagram] None

Inventors

• 小澤 一喜
• 河野 麻衣子
• 篠原 智志
• 田中 真弓

Assignees

• 鹿島建設株式会社

Dates

Publication Date

20260508

Application Date

20241022

Claims (8)

1. A soil conditioner containing magnesium oxide and diatomaceous earth, A soil conditioner in which the diatomaceous earth content is 20 to 200 parts by weight per 100 parts by weight of magnesium oxide.
2. The soil modifier according to claim 1, further containing clay composed of 15% by weight or more of aluminum oxide.
3. The soil modifier according to claim 2, wherein the clay content is 10 to 80 parts by weight per 100 parts by weight of magnesium oxide.
4. The soil modifier according to claim 3, wherein the content of diatomaceous earth and clay is 1:1 to 3:1 by weight.
5. A soil modification method comprising adding and mixing a soil modifier according to any one of claims 1 to 4 to the target soil at a rate of 10 kg to 300 kg per 1 m³ of the target soil.
6. The soil modification method according to claim 5, wherein the water content of the target soil is adjusted to 90% or less before adding the soil modification material.
7. The soil modification method according to claim 5, wherein, after mixing the soil modifier, the cone index of the target soil at 3 days of age is 250 kN/ m² to 800 kN/ m² .
8. The soil modification method according to claim 5, wherein the target soil is dredged soil, shield excavation soil, soil derived from agricultural land, or soil destined for landfill in a waste disposal site.

Description

This invention relates to a soil modifier and a soil modifier method. Conventionally, to facilitate the transportation and handling of soil with high moisture content, and to ensure trafficability for heavy machinery and construction vehicles, soil modifiers containing magnesium oxide or the like have been added to solidify the soil (for example, Patent Documents 1 and 2). Patent No. 4564647Japanese Patent Application Publication No. 10-316967 (a) and (b) are graphs showing the improvement of the corn index at different moisture content levels.This is a graph showing the corn index for different soil amendment formulations.This is a graph showing the corn index for different soil amendment formulations. Soil modifiers, intended for soil solidification, are used to facilitate the transport and handling of soils with high moisture content, and to ensure the trafficability of heavy machinery and construction vehicles. When a soil modifier is added to and mixed with target soil, the soil solidifies. This increases the soil's cone index, making it suitable for the desired application. However, even a soil modifier that effectively solidifies one target soil may not solidify sufficiently when applied to soil from a different region. This is likely due to differences in soil properties across regions. The soil modifier and soil modification method of the present invention were developed in response to this situation, and can sufficiently solidify soils with various properties. Preferred embodiments of the present invention will be described in detail below. The soil conditioner of this embodiment contains magnesium oxide and diatomaceous earth. Magnesium oxide is preferable because it has a soil-solidifying effect, has minimal adverse effects on the ecosystem, and does not raise the soil pH as much as calcium oxide. Diatomaceous earth is a mineral rich in amorphous silicon dioxide. In the soil conditioner, the diatomaceous earth content is 20 to 200 parts by weight per 100 parts by weight of magnesium oxide. This content may also be 25 to 100 parts by weight, or 30 to 60 parts by weight. The soil modifier may further contain clay. Preferably, the clay is composed of 15% or more by weight of aluminum oxide. In particular, if the aluminum oxide is amorphous, it is preferable from the viewpoint of supplying amorphous components to the target soil. The clay content may be 10 to 80 parts by weight, 15 to 80 parts by weight, or 20 to 60 parts by weight per 100 parts by weight of magnesium oxide. Furthermore, when the soil conditioner contains clay, the weight ratio of diatomaceous earth to clay may be 1:1 to 3:1. It may also be 1.5:1 to 3:1, or 2:1 to 3:1. Both diatomaceous earth and clay increase the bulk of the soil conditioner, reducing the water content when the soil conditioner is added and mixed with the target soil, and slowing down solidification. Additionally, both diatomaceous earth and clay, due to their bulk-increasing effect, reduce the pH increase caused by magnesium oxide. The soil modifier may further contain other inorganic base materials besides those mentioned above. Other materials that can be included as inorganic base materials include zeolite, calcium carbonate, gypsum, and paper sludge. By incorporating these as inorganic base materials, it is possible to adjust water absorption and solidification effects, and to suppress the leaching of heavy metals from the solidified soil. The preferred blending ratio of these materials is 20 to 80% by weight, based on the total amount of inorganic base materials including the magnesium oxide, diatomaceous earth, and clay mentioned above. The soil conditioner may further contain a pH adjuster to achieve a desired pH level in the treated soil. Examples of pH adjusters include inorganic salts such as sulfates, hydrochlorides, and nitrates, and any hydrates thereof. The preferred mixing ratio of the pH adjuster is 10 to 20 parts by weight per 100 parts by weight of the total amount of the inorganic base material, including the magnesium oxide, diatomaceous earth, and clay. If the amount is less than 10 parts by weight, the effect of the pH adjuster may be diminished; if it exceeds 20 parts by weight, the original soil conditioner effect may decrease. The pH of the soil before and after adding the soil conditioner can be measured using the pH test method for soil suspensions (JGS 0211-2000). The soil to be modified (target soil) may be dredged soil, shield excavation soil, soil derived from agricultural land, or soil destined for landfill in waste disposal sites. Target soil is, for example, soil with a cone index of less than 200 kN/ m² . Alternatively, the target soil may have a water content (weight of water relative to the weight of solids; expressed in %) of 90% to 120%. If the water content is high, adjustment treatment to reduce it to 70% to 90% by other means (e.g., drying treatment) may be performed before adding the soil modifier. This can reduce the amo