Salted soil solidifying agent and in-situ solidifying method for salted soil

Abstract

The present disclosure provides a saline soil solidifying agent and an in-situ solidifying method for saline soil, belonging to the field of industrial solid waste resource utilization and road engineering. The saline soil solidifying agent comprises a solid waste dry powder and a metahydroxyapatite reinforcing agent; the solid waste dry powder comprises fly ash 20-25 parts by mass, slag powder 30-35 parts by mass, steel slag powder 25-35 parts by mass, and desulfurization gypsum 10-25 parts by mass; the mass of the metahydroxyapatite reinforcing agent is 1%-5% of the mass of the solid waste dry powder; and the saline soil is a sulfate saline soil or a sulfite saline soil. The saline soil solidifying agent can directly use the sulfate in the saline soil as an activator, simultaneously achieving the stabilization of salt and the strengthening of soil structure, and can effectively utilize industrial solid waste, avoid the use of traditional high-energy-consumption cementing materials, reduce construction energy consumption, and relieve environmental protection pressure in road construction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the fields of industrial solid waste resource utilization and road engineering, in particular, to a saline soil salinity-activated saline soil solidifying agent and an in-situ solidification method of saline soil. BACKGROUND

[0002] Due to the presence of high-concentration sulfate and chloride salts in saline soil, it is easy to cause engineering diseases such as salt heaving damage, corrosion failure, and salt freezing synergistic damage, resulting in increased roadbed repair and road maintenance costs. It is a difficult problem in the industry to solidify the saline soil roadbed and ensure the long-term service performance of the saline soil. Traditional cementitious materials such as cement are easily eroded by sulfate and chloride salts, and pose a greater threat to the environment. Using industrial solid waste as a cementitious material for solidifying saline soil can alleviate the corrosion problem of saline soil and achieve resource utilization of solid waste, thereby reducing the pressure on the environment, and thus has attracted widespread attention and application.

[0003] However, there are still limitations in using industrial solid waste-based cementitious materials to solidify saline soil at the present stage. Patent CN114940608A discloses a method for improving sulfate saline soil and a solidifying agent. Although the invention effectively manages sulfate saline soil, the design and preparation of the solidifying agent still rely on the addition of cement, and the activity of the salt in the soil is not utilized. In addition, since the solidifying agent uses cement and magnesium oxide, its economy and environmental friendliness still need to be further investigated.

[0004] Patent CN118930159A discloses a roadbed filler for treating tunnel excavation waste saline loess based on a solidifying agent, which includes 23-27 parts of magnesium slag, 3-5 parts of fly ash, 1-3 parts of an activator, 6-8 parts of a reinforcing agent, and 3-5 parts of an adsorbent. The invention makes full use of industrial solid waste materials and effectively adsorbs sulfate in the soil. However, the preparation of the adsorbent requires high-temperature baking, and the preparation process is relatively complex, consuming time and energy. The above-mentioned patent has a common technical defect, which is that the salt is considered as a harmful substance rather than a usable chemical reaction activator, the activation of solid waste relies on a high-alkaline environment, and it poses a threat to the soil environment. Therefore, there is an urgent need to develop environmentally friendly industrial solid waste-based solidifying agents and green and efficient saline soil solidification methods.

[0005] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0006] The present disclosure aims to overcome the deficiencies of the prior art, and provides a saline soil salinity-activated saline soil stabilizer and an in-situ saline soil stabilization method. The saline soil stabilizer can directly use sulfate in saline soil as an activator, simultaneously achieving salinity stabilization and soil structure strengthening, and can effectively utilize industrial solid waste, avoid the use of traditional high-energy consumption cementing materials, reduce construction energy consumption, and relieve environmental pressure in road construction.

[0007] According to one aspect of the present disclosure, a saline soil salinity-activated saline soil stabilizer is provided, comprising a solid waste dry powder and an aluminate strengthening agent; the solid waste dry powder comprises fly ash 20-25 parts by mass, slag powder 30-35 parts by mass, steel slag powder 25-35 parts by mass, and desulfurization gypsum 10-25 parts by mass;

[0008] The mass of the aluminate strengthening agent is 1%-5% of the mass of the solid waste dry powder;

[0009] The saline soil is sulfate saline soil.

[0010] According to one embodiment of the present disclosure, the specific surface area of the fly ash is not less than 350 m 2 / kg, the specific surface area of the slag powder is not less than 420 m 2 / kg, the specific surface area of the steel slag powder is not less than 450 m 2 / kg, and the specific surface area of the desulfurization gypsum is between 300 m 2 / kg and 350 m 2 / kg.

[0011] According to one embodiment of the present disclosure, the fly ash is fly ash produced by burning lignite or sub-bituminous coal.

[0012] According to one embodiment of the present disclosure, the aluminate strengthening agent is calcium-based aluminate.

[0013] According to one embodiment of the present disclosure, the solid waste dry powder comprises fly ash 25 parts by mass, slag powder 30 parts by mass, steel slag powder 25 parts by mass, and desulfurization gypsum 20 parts by mass; and the mass of the aluminate strengthening agent is 3% of the mass of the solid waste dry powder.

[0014] According to one embodiment of the present disclosure, the solid waste dry powder comprises fly ash 20 parts by mass, slag powder 30 parts by mass, steel slag powder 35 parts by mass, and desulfurization gypsum 15 parts by mass; and the mass of the aluminate strengthening agent is 2% of the mass of the solid waste dry powder.

[0015] According to one embodiment of the present disclosure, the mass content of soluble salt in the sulfate saline soil is not less than 2%.

[0016] According to an embodiment of the present disclosure, the saline soil stabilizer is composed of solid waste dry powder and metakaolin reinforcing agent.

[0017] The solid waste dry powder is composed of fly ash 20-25 parts by mass, slag powder 30-35 parts by mass, steel slag powder 25-35 parts by mass, and desulfurization gypsum 10-25 parts by mass.

[0018] According to another aspect of the present disclosure, a method for in-situ stabilization of saline soil is provided, comprising:

[0019] Step 1, mixing the solid waste dry powder of the above-mentioned saline soil stabilizer with the metakaolin reinforcing agent, then adding water and mixing uniformly to obtain an activated saline soil stabilizer;

[0020] Step 2, incorporating the activated saline soil stabilizer into the saline soil by mechanical mixing;

[0021] Step 3, compacting the saline soil incorporating the saline soil stabilizer to form a subgrade and curing; wherein during the compaction and curing of the saline soil, the soluble salt in the saline soil acts as an activator to activate the saline soil stabilizer, generating ettringite, CaO-SiO2-H2O gel phase and CaO-Al2O3-SiO2-H2O gel phase in-situ while consuming the soluble salt in the saline soil, forming a cemented soil structure and completing the in-situ stabilization of the saline soil.

[0022] According to an embodiment of the present disclosure, the mass of the saline soil stabilizer is 6%-18% of the mass of the saline soil to be stabilized.

[0023] The saline soil salt-activated saline soil stabilizer provided by the present disclosure can utilize the sulfate in the saline soil to react with the silicon-aluminum phase components in the solid waste to generate controllable hydration products, activate the solid waste-based stabilizer, and avoid salt erosion and expansion and other diseases, thereby improving the durability of the saline soil subgrade. Compared with other technologies, the present invention fully utilizes the salt resources in the saline soil as an activation source, avoiding the use of strong alkaline activators to damage the soil environment. At the same time, the saline soil stabilizer of the present invention effectively consumes the salt in the saline soil while ensuring the reactivity of the stabilizer, thereby ensuring the strength of the subgrade. In addition, since industrial solid waste is used as the stabilizing material, the use of traditional high-energy consumption cementitious materials is avoided, reducing resource and energy consumption, alleviating environmental pressure, and widening the high-value utilization path of industrial solid waste, which is conducive to the green development of road engineering. In particular, the low-cost steel slag powder is used in the solid waste dry powder of the present invention to replace part of the slag powder, which expands the utilization mode of steel slag solid waste while reducing the cost of the saline soil stabilizer.

[0024] For the soluble salt content of 3.1% of the sulfate saline soil, after curing with the saline soil curing agent with a mass fraction of not more than 12%, the 7-day compressive strength of the cured saline soil is not less than 1.5 MPa, the 28-day compressive strength is not less than 5 MPa, and the strength loss after 10 cycles of salt freezing (-20℃~45℃ to reflect the extreme environment) is less than 15%. The saline soil curing agent of the saline soil salt excitation of the application has obvious curing effect on the high-soluble salt saline soil compared with common curing agents such as cement.

[0025] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0026] The drawings incorporated in the specification and constituting a part of the specification illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained from these drawings without creative labor for those skilled in the art.

[0027] Figure 1 The unconfined compressive strength diagram of the cured soil sample of each example and comparative example.

[0028] Figure 2 The strength loss rate diagram of the cured soil sample of each example and comparative example caused by salt freeze-thaw test. DETAILED DESCRIPTION

[0029] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example implementations to those skilled in the art. Like reference numerals refer to like elements throughout the description. In addition, the drawings are only schematic and are non-limiting.

[0030] Although relative terms such as "upper", "lower", etc. are used herein to describe one component's relationship to another component in the drawings, such terms are used only for convenience and are not to be construed as limiting the application to the examples described herein. It is understood that if the device of the icon is turned over so that the upper and lower are reversed, the component described as "upper" will become the component described as "lower". When a structure is "on" another structure, it can mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0031] The application provides a saline soil salinity-activated saline soil curing agent and a saline soil in-situ curing method using the saline soil curing agent.

[0032] The saline soil curing agent comprises solid waste dry powder and metakaolin reinforcing agent; the solid waste dry powder comprises fly ash 20-25 parts by mass, slag powder 30-35 parts by mass, steel slag powder 25-35 parts by mass, and desulfurization gypsum 10-25 parts by mass; the mass of the metakaolin reinforcing agent is 1%-5% of the mass of the solid waste dry powder; and the saline soil is sulfate saline soil.

[0033] The saline soil in-situ curing method using the saline soil curing agent comprises:

[0034] Step 1, mixing the solid waste dry powder and the metakaolin reinforcing agent, then adding water and mixing uniformly to obtain an activated saline soil curing agent;

[0035] Step 2, mixing the activated saline soil curing agent into the saline soil by mechanical mixing;

[0036] Step 3, compacting the saline soil into which the saline soil curing agent is mixed to form a subgrade and curing; in the process of compacting and curing the saline soil, the soluble salt in the saline soil acts as an activator to activate the saline soil curing agent, to generate ettringite, CaO-SiO2-H2O gel phase (C-S-H gel phase) and CaO-Al2O3-SiO2-H2O gel phase (C-A-S-H gel phase) in-situ, consume the soluble salt in the saline soil, form a cemented soil structure, and complete the in-situ curing of the saline soil.

[0037] In the application, the soluble salt in the saline soil can activate the saline soil curing agent, so that the solid waste powder is rapidly hydrated to form C-S-H gel phase, so that the saline soil is rapidly cured. In the curing process, sulfate can participate in the formation of ettringite and fill in the voids, and sodium ions can be adsorbed and ion-exchanged by C-S-H gel phase. Therefore, in the early stage of in-situ curing of the saline soil, most of the soluble salt in the saline soil is consumed or cured, and the rapidly formed C-S-H gel phase can provide greater initial strength. In the subsequent curing process, CaO-Al2O3-SiO2-H2O gel phase is gradually formed and further exchanges with sodium ions, to more strongly fix the sodium ions and promote the long-term development of the strength of the cured saline soil. At the same time, gypsum and steel slag promote the continuous generation of ettringite in the curing process to improve the curing strength of sulfur ions, and the continuously generated ettringite microcrystals fill in the voids of the soil body and are wrapped and fixed by the gradually developed gel phase, to realize the continuous cementation of the soil body structure.

[0038] The salted soil salinity-excited salted soil curing agent of the present application does not need to add calcium oxide, calcium hydroxide, magnesium oxide or other high-alkaline components as an excitation agent, which can reduce the cost of the salted soil curing agent on the one hand, and can avoid the environmental pollution risk caused by the additional addition of strong alkali on the other hand.

[0039] In the present application, if the molar concentration of sulfate ions in the soluble salt of the salted soil is not less than twice the molar concentration of chloride ions, the salted soil is regarded as a sulfate salted soil. If the molar concentration of sulfate ions in the soluble salt of the salted soil is 1-2 times the molar concentration of chloride ions, the salted soil is regarded as a sulfite salted soil.

[0040] In an embodiment of the present disclosure, the specific surface area of the fly ash is not less than 350 m 2 / kg, the specific surface area of the slag powder is not less than 420 m 2 / kg, the specific surface area of the steel slag powder is not less than 450 m 2 / kg, and the specific surface area of the desulfurization gypsum is between 300 m 2 / kg and 350 m 2 / kg. In this way, the glass body of the solid waste powder is effectively broken down during the excitation stage to quickly improve the early strength of the cured salted soil; on the other hand, the solid waste releases components such as calcium and aluminum to promote the long-term development of the gel phase and the continuous formation of ettringite microcrystals, which is beneficial to the long-term development of the strength of the cured salted soil and the more complete consumption of soluble salt.

[0041] In an embodiment of the present disclosure, the fly ash is the fly ash produced by the combustion of lignite or sub-bituminous coal. In this way, the development speed of the C-S-H gel phase in the cured salted soil can be improved and the excitation speed of the salted soil curing agent can be reduced.

[0042] In an embodiment of the present disclosure, the aluminate strengthening agent is a calcium-based aluminate. In this way, the continuous development of the C-A-S-H gel phase can be further promoted, which is beneficial to the continuous development of the strength of the cured salted soil and the long-term adsorption / exchange capacity of the soluble salt. In an example, the calcium-based aluminate is calcium aluminate powder, dicalcium aluminate powder or seven calcium dodecyl aluminate powder.

[0043] In an embodiment of the present disclosure, the solid waste dry powder includes 25 parts by mass of fly ash, 30 parts by mass of slag powder, 25 parts by mass of steel slag powder and 20 parts by mass of desulfurization gypsum; the mass of the aluminate strengthening agent is 3% of the mass of the solid waste dry powder.

[0044] In an embodiment of the present disclosure, the solid waste dry powder comprises fly ash 20 parts by mass, slag powder 30 parts by mass, steel slag powder 35 parts by mass, and desulfurization gypsum 15 parts by mass; and the mass of the meta-aluminate reinforcing agent is 2% of the mass of the solid waste dry powder.

[0045] In an embodiment of the present disclosure, the mass content of the soluble salt in the sulfate saline soil is not less than 2%, for example, the mass content of the soluble salt is between 2% and 5%, particularly between 3.0% and 5.0%. For example, the mass content of the soluble salt in the sulfate saline soil is 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9% or 5%.

[0046] In an embodiment of the present disclosure, the saline soil curing agent is composed of a solid waste dry powder and a meta-aluminate reinforcing agent; and the solid waste dry powder is composed of fly ash 20-25 parts by mass, slag powder 30-35 parts by mass, steel slag powder 25-35 parts by mass, and desulfurization gypsum 10-25 parts by mass.

[0047] In other words, the saline soil curing agent provided by the present application is composed of all industrial solid wastes except the meta-aluminate reinforcing agent, and the curing of the saline soil is achieved by the combination of the four kinds of industrial solid waste powders. The saline soil curing agent of the present application does not contain additional strong alkali and does not contain organic materials (such as cellulose adhesives, surfactants, etc.).

[0048] In an embodiment of the present disclosure, the mass of the saline soil curing agent is 6%-18% of the mass of the saline soil to be cured, particularly 8%-12%. For example, the mass of the saline soil curing agent is 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12% of the mass of the saline soil to be cured.

[0049] In an embodiment of the present disclosure, after the activated saline soil curing agent is mixed into the saline soil by mechanical mixing, the water content of the saline soil mixed with the curing agent is between 10% and 18%.

[0050] Optionally, before the saline soil is cured by using the saline soil curing agent, an experiment can be performed to determine the amount of water to be added in actual application. For example, the optimal water content of the saline soil mixed with the curing agent and the natural water content of the saline soil to be cured can be determined by experiment, and then the amount of water to be added in step 1 can be determined.

[0051] In an example, the optimum water content of the saline soil incorporating the solidification agent can be determined by a compaction test.

[0052] In an example, the compaction degree of the in-situ construction can be determined by a compaction test.

[0053] The in-situ solidification effect of the saline soil by the saline soil solidification agent excited by the salt content of the saline soil according to the embodiments of the present disclosure is introduced as follows in multiple examples and comparative examples.

[0054] Example 1

[0055] The in-situ solidification method of the saline soil by the saline soil solidification agent excited by the salt content of the saline soil includes:

[0056] Step 1, preparing the saline soil solidification agent. Fly ash (25 parts by mass), ground granulated blast furnace slag (30 parts by mass), steel slag powder (25 parts by mass), and desulfurization gypsum (20 parts by mass) are uniformly mixed as solid waste dry powder; a calcium-based metakaolin is used as a reinforcing agent, and the addition amount is 1% of the mass of the solid waste dry powder.

[0057] Step 2, preparing the test soil material. The test soil material is a mixture of the saline soil solidification agent and the saline soil to be solidified, and the mass of the saline soil solidification agent is 8% of the mass of the saline soil.

[0058] Step 3, performing a compaction test on the test soil material to determine that the optimum water content is 14%.

[0059] Step 4, mixing the saline soil solidification agent with water according to the optimum water content, and then mixing with the saline soil to be solidified to obtain the solidified soil material. The mass of the saline soil solidification agent is 8% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of the soluble salt is 3.1%.

[0060] Step 5, using vibration compaction to compact the solidified soil material to form a solidified soil.

[0061] Example 2

[0062] The in-situ solidification method of the saline soil by the saline soil solidification agent excited by the salt content of the saline soil includes:

[0063] Step 1, preparing the saline soil solidification agent. Fly ash (25 parts by mass), ground granulated blast furnace slag (30 parts by mass), steel slag powder (25 parts by mass), and desulfurization gypsum (20 parts by mass) are uniformly mixed as solid waste dry powder; a calcium-based metakaolin is used as a reinforcing agent, and the addition amount is 3% of the mass of the solid waste dry powder.

[0064] Step 2, preparing the test soil material. The test soil material is a mixture of the saline soil solidification agent and the saline soil to be solidified, and the mass of the saline soil solidification agent is 8% of the mass of the saline soil.

[0065] Step 3, the test soil is subjected to a compaction test to determine that the optimum moisture content is 14%.

[0066] Step 4, according to the optimal moisture content, the saline soil stabilizer is mixed with water, and then mixed with the saline soil to be stabilized to obtain a stabilized soil material. The mass of the saline soil stabilizer is 8% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of soluble salt is 3.1%.

[0067] Step 5, the stabilized soil material is compacted by vibration compaction to form a compacted body, and the stabilized soil is obtained after standard curing.

[0068] Example 3

[0069] The in-situ stabilization method of saline soil by the saline soil stabilizer activated by the salt content of the saline soil comprises:

[0070] Step 1, preparing the saline soil stabilizer. Fly ash (25 parts by mass), slag powder (30 parts by mass), steel slag powder (25 parts by mass), and desulfurization gypsum (20 parts by mass) are uniformly mixed as a dry solid waste powder; a calcium-based metakaolin is used as a reinforcing agent, and the addition amount is 3% of the mass of the dry solid waste powder.

[0071] Step 2, preparing the test soil. The test soil is a mixture of the saline soil stabilizer and the saline soil to be stabilized, and the mass of the saline soil stabilizer is 12% of the mass of the saline soil.

[0072] Step 3, the test soil is subjected to a compaction test to determine that the optimum moisture content is 17.5%.

[0073] Step 4, according to the optimal moisture content, the saline soil stabilizer is mixed with water, and then mixed with the saline soil to be stabilized to obtain a stabilized soil material. The mass of the saline soil stabilizer is 12% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of soluble salt is 3.1%.

[0074] Step 5, the stabilized soil material is compacted by vibration compaction to form a compacted body, and the stabilized soil is obtained after standard curing.

[0075] Example 4

[0076] The in-situ stabilization method of saline soil by the saline soil stabilizer activated by the salt content of the saline soil comprises:

[0077] Step 1, preparing the saline soil stabilizer. Fly ash (20 parts by mass), slag powder (30 parts by mass), steel slag powder (35 parts by mass), and desulfurization gypsum (15 parts by mass) are uniformly mixed as a dry solid waste powder; a calcium-based metakaolin is used as a reinforcing agent, and the addition amount is 2% of the mass of the dry solid waste powder.

[0078] Step 2, preparation of test soil. The test soil is a mixture of saline soil solidifying agent and saline soil to be solidified, and the mass of the saline soil solidifying agent is 12% of the mass of the saline soil.

[0079] Step 3, compaction test of the test soil to determine the optimum water content of 16%.

[0080] Step 4, according to the optimal water content, the saline soil solidifying agent is mixed with water and then mixed with the saline soil to be solidified to obtain the solidified soil. The mass of the saline soil solidifying agent is 12% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of soluble salt is 3.1%.

[0081] Step 5, the solidified soil is compacted by vibration compaction, and the solidified soil is obtained after standard curing.

[0082] Comparative Example 1

[0083] The method for solidifying saline soil comprises:

[0084] Step 1, preparation of test soil. The test soil is a mixture of ordinary Portland cement and saline soil to be solidified, and the mass of the ordinary Portland cement is 8% of the mass of the saline soil.

[0085] Step 2, compaction test of the test soil to determine the optimum water content of 13.8%.

[0086] Step 3, according to the optimal water content, the ordinary Portland cement is mixed with the saline soil and water to obtain the solidified soil. The mass of the ordinary Portland cement is 8% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of soluble salt is 3.1%.

[0087] Step 4, the solidified soil is compacted by vibration compaction, and the solidified soil is obtained after standard curing.

[0088] Comparative Example 2

[0089] The method for solidifying saline soil comprises:

[0090] Step 1, preparation of test soil. The test soil is a mixture of sulfate-resistant cement and saline soil to be solidified, and the mass of the sulfate-resistant cement is 8% of the mass of the saline soil.

[0091] Step 2, compaction test of the test soil to determine the optimum water content of 14.5%.

[0092] Step 3, according to the optimal water content, the sulfate-resistant cement is mixed with the saline soil and water to obtain the solidified soil. The mass of the sulfate-resistant cement is 8% of the mass of the saline soil. The saline soil is a sulfate saline soil, and the mass content of soluble salt is 3.1%.

[0093] Step 4, the solidified soil material is compacted by vibration compaction to form a solidified soil.

[0094] The strength and durability of the solidified soil samples obtained in Examples 1-4 and Comparative Examples 1-2 are effectively detected and analyzed by compression strength test and salt freeze-thaw cycle test.

[0095] A 30kN pressure testing machine is selected to measure the unconfined compressive strength of the solidified soil samples after 7d and 28d curing, and the measurement results are shown in Figure 1 According to the analysis of the figure, the 7d unconfined compressive strength of the solidified soil sample cured by the saline soil salt-activated saline soil stabilizer provided by the application is basically the same as that of the solidified soil sample cured by anti-sulfate cement and ordinary Portland cement under the same stabilizer dosage; the 28d unconfined compressive strength of the solidified soil sample cured by the saline soil salt-activated saline soil stabilizer provided by the application is significantly higher than that of the solidified soil sample cured by anti-sulfate cement and ordinary Portland cement under the same stabilizer dosage. At the same time, it can be seen from Figure 1 that increasing the dosage of the saline soil salt-activated saline soil stabilizer can further improve the initial strength and long-term strength of the solidified soil sample. This shows that the saline soil salt-activated saline soil stabilizer provided by the application can realize rapid solidification and continuous development of strength of saline soil without additional addition of strong alkaline activator and organic material.

[0096] The temperature condition of the salt freeze-thaw test is set to-10℃-45℃, and the cycle number is 10 times. After the cycle, the durability of different solidified soil samples is compared by strength loss rate. The results of the salt freeze-thaw test are shown in Figure 2 . According to Figure 2 , it can be seen that the strength loss rate of the solidified soil sample formed by the saline soil salt-activated saline soil stabilizer provided by the application is less than that of the solidified soil sample cured by anti-sulfate cement and ordinary Portland cement, and the strength loss of the solidified soil sample cured by ordinary Portland cement is the largest. This shows that the saline soil salt-activated saline soil stabilizer provided by the application significantly improves the salt erosion resistance and durability of the solidified soil. This is mainly because the solid waste components of the saline soil salt-activated saline soil stabilizer effectively fix and consume the soluble salt ions in the saline soil and convert them into hydration products, realizing the consumption and solidification of salt and the development of the strength of the solidified soil, thereby improving the durability of the solidified soil.

[0097] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the features disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

1. A method for in-situ solidification of saline soil, characterized in that, include: Step 1: Mix the solid waste dry powder of the saline soil solidification agent with the calcium-based aluminate reinforcing agent, then add water and mix evenly to obtain the activated saline soil solidification agent; wherein, the saline soil solidification agent is composed of solid waste dry powder and calcium-based aluminate reinforcing agent; the solid waste dry powder is composed of 20-25 parts by weight of fly ash, 30-35 parts by weight of slag powder, 25-35 parts by weight of steel slag powder, and 10-25 parts by weight of desulfurized gypsum; the mass of the calcium-based aluminate reinforcing agent is 1%-5% of the mass of the solid waste dry powder; the saline soil is sulfate saline soil; Step 2: The activated saline soil stabilizer is incorporated into the saline soil by mechanical mixing. Step 3 involves compacting the saline soil mixed with the saline soil solidifier to form a roadbed and then curing it. During the compaction and curing process, the soluble salts in the saline soil act as activators to activate the saline soil solidifier, generating in-situ ettringite, CaO-SiO2-H2O cementitious phases and CaO-Al2O3-SiO2-H2O cementitious phases while consuming the soluble salts in the saline soil, forming a cemented soil structure and completing the in-situ solidification of the saline soil.

2. The in-situ solidification method for saline soil according to claim 1, characterized in that, The specific surface area of ​​the fly ash is not less than 350 m². 2 / kg, the specific surface area of ​​the slag powder is not less than 420 m². 2 / kg, the specific surface area of ​​the steel slag powder is not less than 450 m². 2 / kg, the specific surface area of ​​the desulfurized gypsum is 300 m² / kg. 2 / kg ~ 350 m 2 Between / kg.

3. The in-situ solidification method for saline soil according to claim 1, characterized in that, The fly ash is fly ash produced by the combustion of lignite or bituminous coal.

4. The in-situ solidification method for saline soil according to any one of claims 1 to 3, characterized in that, The solid waste dry powder comprises 25 parts by weight of fly ash, 30 parts by weight of slag powder, 25 parts by weight of steel slag powder, and 20 parts by weight of desulfurized gypsum; the mass of the calcium-based aluminate reinforcing agent is 3% of the mass of the solid waste dry powder.

5. The in-situ solidification method for saline soil according to any one of claims 1 to 3, characterized in that, The solid waste dry powder comprises 20 parts by weight of fly ash, 30 parts by weight of slag powder, 35 parts by weight of steel slag powder, and 15 parts by weight of desulfurized gypsum; the mass of the calcium-based aluminate reinforcing agent is 2% of the mass of the solid waste dry powder.

6. The in-situ solidification method for saline soil according to any one of claims 1 to 3, characterized in that, The mass content of soluble salts in the sulfate saline soil is not less than 2%.

7. The in-situ solidification method for saline soil according to claim 1, characterized in that, The mass of the saline soil solidifying agent is 6% to 18% of the mass of the saline soil to be solidified.

Images