Soil stabilizer

Abstract

This invention provides a soil stabilizing and hardening agent that can impart sufficient strength to special soils where cement alone would result in insufficient strength, while also preventing the leaching of hexavalent chromium and meeting new wastewater discharge standards. [Solution] A soil stabilizing and hardening agent characterized by containing (A) 30 to 90 parts by mass of a sulfonate with a weight-average molecular weight of 1,000 to 100,000, (B) 1 to 8 parts by mass of ferric chloride, (C) 1 to 8 parts by mass of acetate, (D) 1 to 6 parts by mass of polyaluminum chloride, (E) 1 to 6 parts by mass of polycarboxylate, and (F) 1 to 15 parts by mass of L-ascorbic acid.

Description

[Technical Field]

[0001] This invention relates to a soil stabilizing agent, and more specifically, to a soil stabilizing agent that can be mixed with soils that are difficult to harden with cement alone, such as sludge, sediment, and incinerator ash, to impart strength. [Background technology]

[0002] Traditionally, to obtain concrete using cement, Portland cement is generally mixed with aggregates such as sand and gravel to achieve the required strength.

[0003] However, there are some types of soil that are difficult to strengthen even with the addition of cement-based hardening agents, such as black soil which contains a large amount of organic matter (organic substances, organic impurities) and clay minerals, or sludge and mud with a high water content, as well as clay, incinerated ash, volcanic ash, and waste materials. Therefore, several products have been proposed that can be used together with cement to strengthen these special types of soil that cause strength problems.

[0004] For example, Patent Document 1 describes a soil stabilizing agent that can stably harden soil containing organic matter or soil with a high water content (muddy water) such as sludge or bentonite, by mixing potassium carbonate, sodium carbonate, and sodium sulfate, and further adding sodium ligninsulfonate.

[0005] Generally, humic acid contained in special soils or muddy water reacts with CaO in cement paste to produce lime humic acid, which inhibits the progress of the cement hydration reaction. However, Patent Document 1 states that sodium ligninsulfonate acts as a catalyst on potassium carbonate or sodium carbonate, allowing the aggregate to harden rapidly through a direct reaction with cement.

[0006] Furthermore, Patent Document 2 discloses a citric acid solution containing calcium chloride, sodium chloride, potassium chloride, sodium sulfate, and cobalt chloride.

[0007] This Patent Document 2 states that the ionic reactions of calcium chloride, sodium chloride, potassium chloride, sodium sulfate, and cobalt chloride contained in the additives prevent organic matter in the soil from adsorbing calcium ions, thereby facilitating the cement hydration reaction.

[0008] Furthermore, Patent Document 3 discloses a mixture of sodium chloride, potassium chloride, lithium chloride, barium chloride, potassium bromide, nickel chloride, calcium chloride, magnesium chloride, manganese chloride, strontium chloride, and rubidium chloride in predetermined proportions.

[0009] According to this Patent Document 3, when used in combination with Portland cement, needle-shaped crystals are formed by anionic bonding simultaneously with the hydration reaction of Portland cement, transforming it into a water-free crystalline structure that goes beyond simple hydration. This allows for the bonding of organic and inorganic materials, enabling the hardening of all types of soil.

[0010] On the other hand, Patent Document 4 discloses a product containing calcium ligninsulfonate, sodium polycarboxylate, lithium hydroxide, liquid aluminum dihydrogen phosphate, aluminum oxide, and sulfamic acid.

[0011] According to this Patent Document 4, it is stated that the material can be used safely without containing strong acids or strong alkalis, does not pollute the environment, and can be used not only in combination with cement but also as a substitute for cement, making it particularly useful in providing building materials such as roadbed materials for highways and railways, building foundations, and airport ground leveling.

[0012] As mentioned earlier, in this invention, materials that contain organic matter or have a high water content, and for which it is difficult to impart strength (harden) using cement-based hardening agents alone, are simply referred to as "soil." [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 58-138777 [Patent Document 2] Japanese Patent Publication No. 15582 / 1982 [Patent Document 3] Japanese Patent Application Publication No. 9-278504 [Patent Document 4] Chinese Patent Application Publication No. 105018103 Specification [Overview of the project] [Problems that the invention aims to solve]

[0014] For example, construction sludge, a muddy waste generated during construction and excavation work, is difficult to transport due to its high water content. Furthermore, materials such as soil, incinerator ash, and waste generated by natural disasters are often difficult to harden with cement alone, and their disposal frequently poses a problem.

[0015] Several soil stabilizing agents are known to be used with cement to address soils that cause such strength defects. However, conventional alkali metal salt-based agents have poor cohesive properties in soils with high moisture content and sludge, and are not entirely satisfactory from the standpoint of compressive strength and other factors.

[0016] Furthermore, the "Cabinet Order Amending Part of the Sewerage Enforcement Order," promulgated on January 4, 2024, strengthens the exclusion standards for hexavalent chromium compounds, and further consideration is needed in terms of suppressing the leaching of hexavalent chromium after hardening.

[0017] Accordingly, as a result of intensive studies conducted by the present inventors to solve these problems, they have found that by including a predetermined sulfonate, polyaluminum chloride, and polycarboxylate, and further containing ferric chloride, acetate, and L-ascorbic acid, even special soil that would cause poor strength when only cement is used can be firmly solidified to impart sufficient compressive strength, and furthermore, elution of hexavalent chromium can be reliably prevented, thus completing the present invention.

[0018] Accordingly, an object of the present invention is to provide a soil stabilizing and solidifying agent that can impart sufficient strength to special soil which causes poor strength when only cement is used, and can prevent elution of hexavalent chromium to satisfy new effluent standards. [Means for Solving the Problems]

[0019] That is, the present invention relates to the following components (A) to (F): Component (A): 30 to 90 parts by mass of a sulfonate having a weight average molecular weight of 1,000 to 100,000, Component (B): 1 to 8 parts by mass of ferric chloride, Component (C): 1 to 8 parts by mass of an acetate, Component (D): 1 to 6 parts by mass of polyaluminum chloride, Component (E): 1 to 6 parts by mass of a polycarboxylic acid, and Component (F): 1 to 15 parts by mass of L-ascorbic acid, A soil stabilizing and solidifying agent characterized by comprising the above components.

[0020] In general, cement is mixed with aggregates such as sand and gravel and water to form fluid paste-like ready-mixed concrete, which is then solidified into various shapes to obtain concrete. The solidification mechanism in this process is estimated as follows. In other words, when cement, water, and aggregate are mixed, it hardens after a while. During this time, smaller aggregate particles, such as sand, get trapped between larger aggregate particles, such as gravel, and the cement paste binds them together. At this time, when cement and water come into contact, calcium ions are released from the cement and react with the alumina and silicon dioxide contained in the cement to form fine particles. These particles then hydrate and bind together, forming cement paste and hardening.

[0021] On the other hand, as mentioned earlier, there are some materials that are difficult to harden with only a small amount of cement, such as soils containing clay minerals and organic matter, like volcanic ash clay soils such as Kanto loam, red soil, black soil, and high organic soil (Kuroboku soil); soils with high moisture content, such as sediment and dredged soil generated by natural disasters, and industrial waste such as construction sludge; and sludge, such as mud, dredged soil, sea sand, limestone, red soil, incinerator ash, volcanic ash, waste, and sludge.

[0022] To harden soil that is difficult to harden with only a small amount of cement, the soil stabilizing agent according to the present invention plays a role as an auxiliary agent. In other words, unlike when forming concrete, the soil stabilizing agent uses soil containing clay minerals or organic matter, or soil with a high water content, instead of aggregate. This makes it possible to effectively utilize soil, sludge, etc., which have been difficult to dispose of until now.

[0023] The soil stabilizing agent in the present invention contains (A) component: 30 to 90 parts by mass, preferably 50 to 85 parts by mass, of a sulfonate salt with a weight-average molecular weight (Mw) of 1,000 to 100,000. If the proportion of component (A) in the soil stabilizing agent is less than 30 parts by mass, it may be insufficient to coagulate soil with high moisture content. Conversely, if the proportion of component (A) exceeds 90 parts by mass, it may become too hard when mixed with the soil to be strengthened, making it impossible to uniformly mix the soil stabilizing agent and potentially preventing the acquisition of sufficient compressive strength.

[0024] Component (A) is preferably one or more selected from the group consisting of lignin sulfonate, naphthalene sulfonate and formaldehyde condensate, polystyrene sulfonate, aminosulfonate, and melanin sulfonate, and may include two or more of the same type. Furthermore, the type of metal salt in these sulfonates is not particularly limited, and examples include Na salt, K salt, Ca salt, Mg salt, etc. Among these, Ca salt and Mg salt are preferred, and component (A) consisting of these is particularly excellent in improving soil cohesiveness. Furthermore, the weight-average molecular weight (Mw) of component (A): sulfonate is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, from the viewpoint of imparting cohesiveness to the soil by component (A) and having excellent solubility when mixed with soil.

[0025] Furthermore, ingredient (A) is available as a commercially available product, for example, Sun Extract SCP (product name of Nippon Paper Industries Co., Ltd.), Mighty 100, and Mighty 150 (product names of Kao Corporation).

[0026] Furthermore, the soil stabilizing agent in the present invention contains 1 to 8 parts by mass, preferably 2 to 5 parts by mass, of component (B): ferric chloride. If the proportion of component (B) in the soil stabilizing agent is less than 1 part by mass, it may become difficult to adequately prevent the leaching of hexavalent chromium, which will be discussed later. Conversely, if it exceeds 8 parts by mass, soil coagulation may be delayed, and the compressive strength after soil hardening may be insufficient.

[0027] Furthermore, the soil stabilizing agent in the present invention contains 1 to 8 parts by mass, preferably 2 to 4 parts by mass, of component (C): acetate. If the proportion of component (C) in the soil stabilizing agent is less than 1 part by mass, it may become difficult to adequately prevent the leaching of hexavalent chromium. Conversely, if it exceeds 8 parts by mass, soil coagulation may be slowed, and the compressive strength after soil hardening may be insufficient. In addition, the type of metal salt constituting the acetate is not particularly limited, and examples include Na salt, K salt, Ca salt, Mg salt, etc.

[0028] Furthermore, the soil stabilizing agent in the present invention contains 1 to 6 parts by mass, preferably 2 to 4 parts by mass, of component (D): polyaluminum chloride. If the proportion of component (D) in the soil stabilizing agent is less than 1 part by mass, it may be difficult to impart sufficient cohesive force to the target soil. Conversely, if it exceeds 6 parts by mass, the cohesiveness of the soil may increase too quickly, resulting in uneven mixing of the soil stabilizing agent, and potentially preventing the acquisition of sufficient compressive strength.

[0029] This component (D) is available commercially, and examples include polyaluminum chloride (manufactured by Shin Nippon Gosei Co., Ltd.).

[0030] Furthermore, the soil stabilizing agent in the present invention contains 1 to 6 parts by mass, preferably 2 to 4 parts by mass, of component (E): polycarboxylate. If the proportion of component (E) in the soil stabilizing agent is less than 1 part by mass, it may be difficult to impart sufficient cohesive force to the target soil. Conversely, if it exceeds 6 parts by mass, the soil stabilizing agent may not mix uniformly when mixed with the soil.

[0031] (E) Component: The polycarboxylic acid portion of the polycarboxylate salt can be, for example, polyacrylic acid, polymethacrylic acid, acrylic acid / maleic acid copolymer, acrylic acid / vinyl acetate copolymer, acrylic acid / sulfonic acid copolymer, etc. The metal salt of the polycarboxylate salt can be, for example, Na salt, K salt, Ca salt, Mg salt, etc. Furthermore, the weight-average molecular weight (Mw) of the polycarboxylate salt of component (E) is preferably between 1,000 and 100,000, and more preferably between 2,000 and 20,000, from the viewpoint of imparting cohesiveness to the soil by component (E) and having excellent solubility when mixed with soil.

[0032] Furthermore, the soil stabilizing agent in the present invention contains 1 to 15 parts by mass, preferably 3 to 8 parts by mass, of component (F): L-ascorbic acid. If the proportion of component (F) in the soil stabilizing agent is less than 1 part by mass, it may be difficult to adequately prevent the leaching of hexavalent chromium. Conversely, if it exceeds 15 parts by mass, the compressive strength after the soil has been hardened may be insufficient.

[0033] Furthermore, the soil stabilizing agent of the present invention may include, if necessary, components other than those (A) to (F). That is, for example, it may include preservatives, viscosity modifiers, solidification inhibitors, pigments, pH adjusters, etc. Moreover, the soil stabilizing agent of the present invention may be dissolved in water or the like to form a solution, or it may be used in a dry powder state.

[0034] On the other hand, known cements can be used as the cement used in conjunction with the soil stabilizing agent in the present invention. Generally, examples include Portland cement, as well as mixed cements containing blast furnace cement, fly ash cement, silica cement, etc., or other eco-cements, but the invention is not limited to these.

[0035] Furthermore, the mixing ratio of soil stabilizer and cement varies depending on the type of soil and its moisture content, as well as the intended use of the soil after hardening, making it difficult to specify a general ratio. However, for example, when providing sufficient strength for use as road concrete to reddish-brown soil formed from decomposed volcanic ash, which is rich in organic matter and has a moisture content of about 15-30% by mass, it is recommended to include approximately 2-6 parts by mass of Portland cement and 0.03-0.1 parts by mass of soil stabilizer for every 100 parts by mass of red soil.

[0036] The soil stabilizing agent according to the present invention is applied to soils that are difficult to harden with cement alone, such as soils containing organic matter or soils with high moisture content, and is added together with cement. In this case, as described above, it is necessary to at least increase the strength of the target soil and prevent the chromium (Cr) contained in the cement from leaching out as harmful hexavalent chromium.

[0037] According to the present invention, it becomes possible to impart strength to soil that is difficult to harden with cement alone, and moreover, to prevent the leaching of hexavalent chromium. Although the detailed mechanism is not entirely clear, the inventors currently believe it to be as follows.

[0038] In other words, when increasing the strength of soil, the soil in question usually contains a lot of water. Also, because the particles that make up this soil (soil particles) are very small, simply mixing them with cement will not easily produce sufficient strength. Therefore, it is necessary to enlarge these tiny soil particles, but some particles in the soil are negatively charged and repel each other electrostatically, making aggregation difficult.

[0039] In this invention, by using positively charged component (D): polyaluminum chloride, or iron acetate, which is a reaction product of component (B): ferric chloride and component (C): acetate, negatively charged fine soil particles can be electrically neutralized and agglomerated to form small blocks (primary aggregated particles).

[0040] In addition, in this invention, the small blocks (primary aggregated particles) obtained above can be made into larger aggregates using component (E): polycarboxylate, which is a polymer flocculant. In this process, water in the soil particles is also dissociated. Thus, component (D): polyaluminum chloride and component (E): polycarboxylate promote the aggregation of soil particles, and the larger polymer aggregated soil particles (secondary particles) work to increase the strength of the soil.

[0041] In addition, the above component (E): polycarboxylate is also considered to act as an AE water reducing agent. In other words, when this component (E) is present around cement particles, the component (E) serving as a water reducing agent chemically adsorbs around the cement particles, thereby making it difficult for aggregates to form, and is considered to have an effect of dispersing cement particles. Furthermore, it can facilitate water penetration into cement particles to increase hydration activity, thereby reducing the unit water amount required to obtain concrete strength.

[0042] As described above, polyaluminum chloride in the soil stabilization hardener condenses fine water-containing soil particles into aggregated particles, and the polycarboxylate crosslinks these aggregated particles into large aggregated soil particles. Through this process, water molecules retained by the fine soil particles are dissociated. In addition, sulfonates and carboxylic acids having specific molecular weights and structures also act as AE water reducing agents for cement, and can impart sufficient compressive strength to all types of soil, including soil with high moisture content.

[0043] On the other hand, in order to prevent chromium that may be generated during the cement production process from being eluted as hexavalent chromium (CrO4 2- , CrO7 2- ), component (F) contained in the soil stabilization hardener of the present invention, L-ascorbic acid, is used to reduce chromate ions in cement as described below, reducing hexavalent chromium to trivalent chromium (Cr 3+ ) for detoxification. CrO4 2- + 3C6H8O6 → Cr 3+ + 3C6H6O6 + 2H2O + 2OH - CrO7 2- + 6C6H8O6 → 2Cr 3+ + 6C6H6O6 + 5H2O + 2OH -

[0044] Here, component (F): L-ascorbic acid is added to the soil to be strengthened along with cement. Even if the soil hardens like concrete and component (F): L-ascorbic acid becomes trapped in the hardened material, when rainwater penetrates the hardened material, the L-ascorbic acid also dissolves. As a result, it reacts with hexavalent chromium that has dissolved from the hardened material and is reduced to trivalent chromium, rendering it harmless.

[0045] In summary, the soil stabilizing agent according to the present invention contains predetermined amounts of components (A) to (F) as described above. Component (D): polyaluminum chloride, component (B): ferric chloride, and component (C): acetate electrically neutralize the water-containing fine soil particles in the soil, forming aggregated particles (primary aggregated particles). Component (E): polycarboxylate cross-links these primary aggregated particles, forming larger aggregates while simultaneously removing water from the soil particles. When mixed with cement in this state, it becomes a paste, ultimately providing strength to the target soil. Furthermore, component (A): sulfonate with an aromatic ring and component (E): polycarboxylate also act as AE water-reducing agents, improving workability when hardening the target soil. Moreover, the inclusion of component (F): L-ascorbic acid reduces harmful hexavalent chromium contained in cement, etc., to harmless trivalent chromium. Based on this mechanism, the soil stabilizing agent according to the present invention can firmly solidify even soils with high moisture content and many fine particles through primary and secondary aggregation, achieving sufficient compressive strength. Furthermore, by utilizing the reducing effect and converting harmful hexavalent chromium into trivalent chromium through a chemical reaction, it becomes possible to remove hexavalent chromium almost completely.

[0046] By strengthening the target soil in this way, it becomes possible to improve the work efficiency of excavation operations by dump trucks and ensure ground bearing capacity and trafficability for construction machinery. Furthermore, it becomes possible to effectively utilize soil and concrete sludge that were previously difficult to dispose of, for example, by using the hardened soil as roadbed material or recycling the ready-mix concrete sludge into recycled crushed stone or recycled ready-mix concrete. If the solidified soil is applied to the topsoil of embankments and levees using the soil flow method or spraying method, it can be used to prevent debris flows and the collapse of levees and embankments. [Effects of the Invention]

[0047] According to the present invention, it is possible to impart sufficient strength to special soils that would otherwise suffer from insufficient strength if cement alone were used, while reliably preventing the leaching of hexavalent chromium. Furthermore, by using the soil stabilizing agent of the present invention together with cement, it becomes possible to effectively utilize soils that have previously been difficult to treat. [Modes for carrying out the invention]

[0048] The present invention will be described in more detail below based on examples, etc., but the present invention is not limited to these. [Examples]

[0049] (Example 1) <Production of test-prepared sludge> 9.5 kg of red clay containing 24% by mass of moisture and 0.5 kg of Portland cement were prepared and mixed for 30 minutes using a 10 L stand mixer with a stirrer (manufactured by KALELAISU) to prepare the soil mixture to which the soil stabilizing agent would be added.

[0050] Furthermore, the soil stabilizer according to Example 1 was prepared by preparing the components (A) to (H) listed below, along with water, to form the soil stabilizer shown in Table 1. Note that two types of component (A), (A1) and (A2), were prepared. The soil stabilizer prepared in Example 1 was in aqueous solution form.

[0051] Then, 15 g of the soil stabilizing agent according to Example 1, obtained above, was added to 10 kg of the previously prepared mixed soil to be added, and the mixture was mixed for 30 minutes using the stand mixer with a stirrer described above to obtain the test prepared mixed soil according to Example 1.

[0052] (A1) Ingredients: Calcium magnesium lignin sulfonate (manufactured by Nippon Paper Industries, product name "Sun Extract CP", weight-average molecular weight Mw52000), (A2) Ingredients: Sodium salt of a condensate of naphthalene sulfonic acid and formaldehyde (manufactured by Kao Corporation, product name "Mighty 150", weight-average molecular weight Mw 14500) (B) Ingredients: Ferric chloride (manufactured by Ikoma Pharmaceutical Industry Co., Ltd., product name "Iron (III) chloride") (C) Ingredients: Sodium acetate (Manufactured by Morishita Sangyo Co., Ltd. Product name: "Product additive sodium acetate (anhydrous)") (D) Ingredients: Polyaluminum chloride (manufactured by Shin Nippon Kasei Co., Ltd., product name "Polyaluminum Chloride") (E) Ingredients: Sodium polyacrylate (Sunopco Corporation, product name "SN Despersant", weight-average molecular weight Mw10000) (F) Ingredients: L-ascorbic acid (manufactured by Morishita Sangyo Co., Ltd., product name "Food Additive Vitamin C") (G) Ingredients: Zeolite (manufactured by Mizusawa Chemical Co., Ltd., product name "TSC Zeolite") (H) Ingredients: Preservative (Permachem Asia Co., Ltd., product name "Topside 88")

[0053] [Table 1]

[0054] <Preparation of compressive strength test specimens> First, the test-prepared soil mixture obtained above was poured into a cylindrical mold with a diameter of 50 mm and a height of 100 mm, so that it was completely filled. Next, a 1.5 kg rammer (compactor) was dropped from a height of 20 cm onto the test-prepared soil mixture in the mold to compact the first layer. Then, additional test-prepared soil mixture was poured in to fill all the gaps in the mold formed by the first layer of compaction, and the rammer was dropped again from a height of 20 cm to compact the second layer. Finally, additional test-prepared soil mixture was poured in to fill all the gaps in the mold formed by the second layer of compaction, and the rammer was dropped again from a height of 20 cm to compact the third layer. After that, it was left at room temperature for 7 days, and then removed from the mold to obtain a cylindrical compressive strength test specimen at 7 days of age according to Example 1.

[0055] The compressive strength of the specimens obtained above was measured according to the concrete compressive strength test method specified in JIS A1108:2018. The results are shown in Table 1.

[0056] (Examples 2-4, Comparative Examples 1-3) Soil stabilizing agents for Examples 2-4 and Comparative Examples 1-2 were prepared to have the compositions shown in Table 1. Note that no soil stabilizing agent was prepared for Comparative Example 3.

[0057] Next, in Example 2 and Comparative Examples 1-2, 15 g of soil stabilizing agent was added to 10 kg of the mixed soil to be added, prepared in the same manner as in Example 1, and the mixture was obtained using the aforementioned stand mixer with a stirrer in the same manner as in Example 1 to obtain the test prepared mixed soil. On the other hand, in Examples 3-4, 5 g of soil stabilizing agent was added to 10 kg of the mixed soil to be added, prepared in the same manner as in Example 1, and the mixture was obtained using the stand mixer with a stirrer in the same manner as in Example 1 to obtain the test prepared mixed soil. Furthermore, in Comparative Example 3, no soil stabilizing agent was added to 10 kg of the mixed soil to be added, prepared in the same manner as in Example 1, and the mixed soil was mixed using the stand mixer with a stirrer in the same manner as in Example 1 to obtain the test prepared mixed soil.

[0058] These test-prepared soil mixtures were compacted using a rammer with a cylindrical mold in the same manner as in Example 1, and then left at room temperature in the same manner as in Example 1 to obtain compressive strength test specimens for Examples 2-4 and Comparative Examples 1-3. The compressive strength was then measured in the same manner as in Example 1. The results are shown in Table 1.

[0059] (Example 5) 100g of Portland cement was mixed with 10g of water, and 0.05g of the soil stabilizing agent obtained in Example 1 was added. The mixture was then mixed using a stainless steel bowl to create a test sphere with a diameter of approximately 5cm.

[0060] Next, water was gently poured into a container until the entire test sphere obtained above was submerged. After 24 hours, the concentration of hexavalent chromium dissolved in the water was measured using a Pack Test (manufactured by Kyoritsu Chemical Laboratory). The results are shown in Table 2.

[0061] [Table 2]

[0062] (Example 6, Comparative Example 4) In preparing the test spheres, the test spheres according to Example 6 were prepared in the same manner as in Example 5, except that 0.05 g of the soil stabilizing agent obtained in Example 3 was added. In addition, test spheres according to Comparative Example 4 were prepared in the same manner as in Example 5, but without adding the soil stabilizing agent. For these, the concentration of hexavalent chromium dissolved in water in a container was measured in the same manner as in Example 5. The results are shown in Table 2.

[0063] First, as is clear from the results of Examples 1-4 and Comparative Examples 1-3, it was found that the soil stabilizer according to the present invention can effectively impart strength to the soil. Furthermore, from the results of Examples 5-6 and Comparative Example 4, it was found that the soil stabilizer according to the present invention can reliably suppress the elution of hexavalent chromium.

Claims

1. The following components (A) to (F), (A) Components: 30 to 90 parts by mass of a sulfonate with a weight-average molecular weight of 1,000 to 100,000. (B) Components: 1 to 8 parts by mass of ferric chloride (C) Component: 1 to 8 parts by mass of acetate, (D) Component: 1 to 6 parts by mass of polyaluminum chloride (E) Component: 1 to 6 parts by mass of polycarboxylic acid, (F) Component: 1 to 15 parts by mass of L-ascorbic acid, A soil stabilizing and hardening agent characterized by containing [a specific ingredient / component].

2. The soil stabilizing agent according to claim 1, wherein component (A) is one or more selected from the group consisting of lignin sulfonate, naphthalene sulfonate and aldehyde condensate, polystyrene sulfonate, aminosulfonate, and melanin sulfonate.

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