A wet soil dewatering curing agent, a preparation method thereof and a wet soil dewatering method

Abstract

The application discloses a kind of over-wet soil precipitation curing agent and preparation method thereof, over-wet soil precipitation method, and is related to road engineering technical field.The over-wet soil precipitation curing agent includes the following mass percentages of raw materials: cement 10-20%, carbide slag 20-30%, mineral powder 50-69% and amino-modified polyacrylonitrile fiber 0.1-1%;The amino-modified polyacrylonitrile fiber is polyacrylonitrile fiber with surface-introduced amino groups.The over-wet soil precipitation curing agent provided by the application can quickly reduce the water content of over-wet soil, improve the strength of soil body, and is environmentally friendly and low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering, and particularly relates to a wet soil dewatering curing agent, a preparation method thereof and a wet soil dewatering method. BACKGROUND

[0002] Earthwork filling subgrade is a common type of foundation in domestic road construction, which is located below the pavement structure and directly bears the load of the pavement and the influence of the natural environment. Earthwork filling subgrade mainly compacts the soil body through machinery to make the soil body more dense and reduce the porosity, thereby improving the overall stability and bearing capacity of the subgrade. In addition, the friction and mutual bite effect between coarse-grained soils and the enhancement of molecular attraction between fine-grained soils further improve the strength and stability of the soil body. The construction process of earthwork filling subgrade is relatively simple and does not require complex equipment and technology, so the construction cost is relatively low. At the same time, the earthwork material is widely available and easy to obtain, which makes the earthwork filling subgrade more economically advantageous.

[0003] The raw soil required for earthwork filling subgrade is generally obtained from the in-situ soil around the project site. Due to the influence of underground water immersion or rainfall, these soils usually have a high water content and belong to wet soil. Wet soil cannot be directly applied to subgrade filling, mainly because high water content will cause soil particles to be wrapped in a thick water film. During mechanical compaction, this layer of water film will hinder the discharge of air, making the soil particles unable to effectively aggregate, resulting in a decrease in soil layer density. In addition, water is incompressible, and a thick water film will further affect the compaction effect of the soil body, thereby weakening the overall performance of the subgrade. Therefore, before the construction of earthwork filling subgrade, the wet soil must be dewatered to ensure that it meets the construction requirements.

[0004] In order to effectively reduce the water content of wet soil, the traditional method usually uses natural airing or adds materials such as lime. However, natural airing is limited by weather conditions, has low efficiency and a long period; although the addition of lime can accelerate dewatering, it may cause the soil filling subgrade to crack due to the swelling of the water-absorbed lime, and increase the engineering cost. Therefore, it is particularly important to develop an efficient, environmentally friendly and economical wet soil dewatering material. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a wet soil dewatering curing agent that can quickly reduce the water content of wet soil, improve the strength of the soil body, and is environmentally friendly and low in cost.

[0006] In order to solve the above technical problems, the present application provides a wet soil dewatering curing agent, which comprises the following raw materials in mass percentage: cement 10-20%, carbide slag 20-30%, mineral powder 50-69% and amino-modified polyacrylonitrile fiber 0.1-1%.

[0007] The amino-modified polyacrylonitrile fiber is a polyacrylonitrile fiber with amino groups introduced on the surface.

[0008] As an improvement of the above technical solution, the specific surface area of the mineral powder is 450 m 2 / kg~550 m 2 / kg.

[0009] As an improvement of the above technical solution, the specific surface area of the cement is 400 m 2 / kg~500 m 2 / kg.

[0010] As an improvement of the above technical solution, the fiber length of the amino-modified polyacrylonitrile fiber is 10 mm~30 mm.

[0011] As an improvement of the above technical solution, the content of calcium hydroxide in the carbide slag is ≥85% by mass percentage.

[0012] The cement is a Portland cement.

[0013] As an improvement of the above technical solution, the raw material of the amino-modified polyacrylonitrile fiber includes polyacrylonitrile fiber 15%~30%, ethylenediamine 10%~20%, and water 60%~75% by mass percentage.

[0014] As an improvement of the above technical solution, the amino-modified polyacrylonitrile fiber is prepared by the following method:

[0015] Water and ethylenediamine are mixed to prepare an ethylenediamine solution.

[0016] Polyacrylonitrile fiber is immersed in the ethylenediamine solution to obtain a mixture.

[0017] The mixture is heated to 60°C~80°C and maintained at this temperature for 10~14 hours of reflux, and the fiber is taken out and rinsed with clean water.

[0018] The rinsed fiber is dried to obtain the amino-modified polyacrylonitrile fiber.

[0019] Correspondingly, the second aspect of the present application provides a preparation method of a wet soil dewatering curing agent, for preparing the wet soil dewatering curing agent described above, comprising the following steps:

[0020] (1) The cement, carbide slag, and mineral powder are dried respectively, and the dried cement and mineral powder are respectively subjected to ball milling treatment.

[0021] (2) According to the proportioning, the treated cement, carbide slag, and mineral powder in step (1) are uniformly mixed, and then the amino-modified polyacrylonitrile fiber is added and uniformly mixed to obtain the wet soil dewatering curing agent.

[0022] As the improvement of the above technical scheme, in step (1), the dry cement is subjected to ball milling under the following conditions: ball milling time is 40-80 min, rotation speed is 400-600 r / min, and ball-to-material ratio is 3:1-5:1.

[0023] The dry mineral powder is subjected to ball milling under the following conditions: ball milling time is 90-150 min, rotation speed is 400-600 r / min, and ball-to-material ratio is 3:1-5:1.

[0024] As the improvement of the above technical scheme, before step (2), the method further comprises a step of preparing amino-modified polyacrylonitrile fibers, and the preparation method of the amino-modified polyacrylonitrile fibers comprises the following steps:

[0025] Water and ethylenediamine are mixed under ice bath condition to prepare an ethylenediamine solution;

[0026] The polyacrylonitrile fibers are completely immersed in the ethylenediamine solution to obtain a mixture;

[0027] The mixture is heated to 60-80℃, and the temperature is maintained for reflux for 10-14 hours, and then cooled to room temperature, the fibers are taken out and washed with clean water;

[0028] The washed fibers are dried at 40-60℃ for 10-16 hours to obtain the amino-modified polyacrylonitrile fibers.

[0029] Correspondingly, the third aspect of the present application provides a method for dewatering over-wet soil, which comprises the following steps: adding an over-wet soil dewatering curing agent into the over-wet soil and stirring uniformly, waiting for the water content of the over-wet soil to decrease, and when the water content of the over-wet soil decreases to a preset water content, the dewatering treatment of the over-wet soil is completed, and a roadbed filler is collected; the over-wet soil dewatering curing agent is the over-wet soil dewatering curing agent described above.

[0030] The present application has the following beneficial effects: the raw materials of the over-wet soil dewatering curing agent in the embodiment include cement 10-20%, carbide slag 20-30%, mineral powder 50-69%, and amino-modified polyacrylonitrile fiber 0.1-1%. The over-wet soil dewatering curing agent with the above formulation can realize the dual dewatering effect of physical adsorption and chemical reaction, can quickly reduce the water content of over-wet soil, and can improve the strength of the soil. The amino-modified polyacrylonitrile fiber is introduced into the formulation, the conversion between kinetic energy and thermal energy is realized through the interaction between water molecules in the over-wet soil and the hydrophilic group-amino group in the fiber, and then the fiber releases heat, thereby improving the dewatering rate of the over-wet soil. In addition, the introduction of the amino-modified polyacrylonitrile fiber can also effectively improve the durability of the over-wet soil. The cement and mineral powder in the over-wet soil dewatering curing agent serve as cementitious materials, and through the hydration reaction and heat release effect of the cement and mineral powder, the dewatering rate of the over-wet soil is significantly improved. In addition, the cement and mineral powder can produce a synergistic effect with the amino-modified polyacrylonitrile fiber, and the fiber can absorb the water vapor generated by the reaction of the cement and mineral powder, thereby achieving the effect of liquid heat release, and making the heating process of the whole system more durable. The carbide slag in the over-wet soil dewatering curing agent serves as an activator, can improve the hydration efficiency of the mineral powder, and is low in cost, belongs to the recycling of industrial solid waste, and is friendly to the environment. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below. The present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise specified, the specific techniques or conditions in the embodiments are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. If the manufacturer of the raw materials is not specified, it is a conventional product that can be obtained by purchase in the market.

[0033] The present embodiment discloses an over-wet soil dewatering curing agent, which comprises the following raw materials in mass percentage: cement 10-20%, carbide slag 20-30%, mineral powder 50-69%, and amino-modified polyacrylonitrile fiber 0.1-1%.

[0034] The amino-modified polyacrylonitrile fiber is a polyacrylonitrile fiber with amino groups introduced on the surface.

[0035] The over-wet soil dewatering curing agent with the formulation of the present embodiment can quickly absorb the water in the soil through physical and chemical effects, reduce the water content of the soil, and improve the strength and stability of the soil. At the same time, the over-wet soil dewatering curing agent of the present embodiment is low in preparation cost and environmentally friendly, is convenient for large-scale production, and can meet the actual needs of engineering projects.

[0036] It is worth noting that excessively wet soil refers to soil with a high water content, such as soil with a water content of 20% to 45%. Because such soil is in a water-saturated state for a long time, if it is used directly for construction, it is very easy to produce the so-called "springy soil" phenomenon, which leads to ineffective compaction. Furthermore, after completion, under the influence of vehicle loads, the subgrade and pavement are prone to settlement, deformation, and loss of stability. To overcome these difficulties, this embodiment proposes an excessively wet soil dewatering and solidification agent. The excessively wet soil dewatering and solidification agent is used to treat excessively wet soil for dewatering and solidification. Under the combined action of hydration reaction and fiber exothermic reaction, the excessively wet soil can be rapidly dewatered. The treated excessively wet soil is then used as subgrade filler. After compaction, the remaining active ingredients in the excessively wet soil dewatering and solidification agent can form a gel-like network structure under the activation of hydroxide ions, filling the soil pores and thus enhancing the soil's bearing capacity and stability. Therefore, the excessively wet soil treated with the soil dewatering and solidification agent of this embodiment can not only meet the construction requirements, but also have good stability and durability in long-term use, effectively avoiding the problem of roadbed and pavement damage caused by excessive soil moisture content.

[0037] To further explain, when cement comes into contact with excessively wet soil, due to electrostatic forces, cement particles firmly adhere to the surface of the soil. While competing with soil particles for water, this prevents soil particles from agglomerating, increasing the surface area of ​​the excessively wet soil and thus improving drainage efficiency. After the cement hardens, some soil particles transform into cement-soil, acquiring a certain degree of hardness and becoming usable as aggregate, thereby enhancing the strength and stability of the roadbed.

[0038] Mineral powder is an industrial solid waste generated during blast furnace metal smelting. Its main component is calcium aluminosilicate, existing in a glassy state. Because the activity of mineral powder is lower than that of cement, during the initial mixing process, it mainly adsorbs onto the surface of overly wet soil, causing large soil clumps to decompose into smaller particles, thereby increasing the soil's surface area. After being compacted as roadbed filler, the overly wet soil is then subjected to OH... - Under the influence of ions, the glassy substances in the mineral powder gradually dissolve, releasing elements such as silicon, calcium, and aluminum. These elements recombine in ionic form to form CSH gel. These gels, together with the hydration products of cement that have not fully reacted during the precipitation stage, form a network framework that provides strength support for solidifying overly wet soil, fills voids in the soil, and further improves the mechanical properties and durability of the soil.

[0039] Calcium carbide slag is a byproduct of industrial production, mainly derived from the waste residue left after the production of acetylene gas from calcium carbide. It is rich in calcium hydroxide. When calcium carbide slag comes into contact with excessively wet soil, it dissolves in the soil moisture and releases a large amount of OH-. -ions. These ions act as activators, which can activate the activity of the mineral powder, thereby avoiding the excessive consumption of cement in the precipitation stage, which cannot provide sufficient alkaline environment for the reaction of the mineral powder. In addition, the abundant calcium ions in the carbide slag help to promote the formation of the cementitious network in the system, thereby enhancing the early mechanical properties of the over-wet soil.

[0040] The amino-modified polyacrylonitrile fiber used in the embodiment refers to polyacrylonitrile fiber with improved hydrophilicity, in which a large number of hydrophilic groups, i.e., amino groups, are introduced onto the surface of the polyacrylonitrile fiber, thereby significantly improving the hydrophilic property. By introducing the strong hydrophilic amino groups onto the surface of the polyacrylonitrile fiber, the ability of the polyacrylonitrile fiber to compete with soil particles for water is improved, so that the polyacrylonitrile fiber more easily absorbs water in the soil particles, contacts and wraps the water film of the soil particles, and improves the speed of water evaporation in the over-wet soil. After the amino-modified polyacrylonitrile fiber absorbs water, the hydrophilic groups on the fiber combine with water molecules, and the water molecules change from a random motion state to a stationary state. According to the law of conservation of energy, the kinetic energy of the water molecules at this time is converted into heat energy, which is manifested as the release of heat by the amino-modified polyacrylonitrile fiber, thereby accelerating the evaporation of water in the over-wet soil. In addition, the hydration reaction caused by the cement and the mineral powder generates heat, which causes part of the water in the over-wet soil to evaporate in the form of water vapor. A part of the evaporated water vapor is adsorbed on the amino-modified polyacrylonitrile fiber, which changes from a gaseous state to a liquid state. The liquefaction process also generates heat, which makes the heat release process in the whole system more sustainable, and further accelerates the efficiency of the over-wet soil dewatering. Therefore, by introducing the amino-modified polyacrylonitrile fiber into the over-wet soil dewatering and solidifying agent, the efficiency and duration of the heat generation of the whole system can be improved, so that most of the water in the over-wet soil evaporates in the form of water vapor, and a small part of the water is transferred to the fiber. The water transferred to the fiber does not affect the mutual aggregation of soil particles during the compaction process. On the contrary, after the soil is compacted, the water remaining on the fiber will gradually evaporate over time, effectively improving the shrinkage and stopped hydration reaction in the soil body caused by water loss, thereby improving the compactness of the soil body, reducing the shrinkage, and improving the durability.

[0041] In one embodiment, the specific surface area of the mineral powder is 450 m 2 / kg to 550 m 2 / kg. Within this specific surface area range, the water requirement of the mineral powder can reach a maximum value, which is beneficial to reduce the water content of the soil body and improve the dewatering efficiency. If the specific surface area of the mineral powder is too large or too small, the water requirement of the mineral powder will be reduced, thereby affecting the dewatering efficiency.

[0042] Specifically, the specific surface area of the mineral powder is exemplarily 450 m 2 / kg, 460 m 2 / kg, 470 m 2 / kg, 480 m 2 / kg, 490 m 2 / kg, 510m 2 / kg, 520m 2 / kg, 530m 2 / kg, 540m 2 / kg, 550m 2 / kg, 560m 2 / kg, but not limited to this.

[0043] In an embodiment, the specific surface area of the cement is 400m 2 / kg to 500m 2 / kg. When the specific surface area of the cement is controlled in this range, the hydration rate of the cement can be further improved, and the water-reducing efficiency of the cement can be further enhanced. When the specific surface area of the cement is maintained in the range of 400m 2 / kg to 500m 2 / kg, higher water-reducing efficiency and economic benefits can be achieved.

[0044] Specifically, the specific surface area of the cement is exemplarily 400m 2 / kg, 410m 2 / kg, 420m 2 / kg, 430m 2 / kg, 440m 2 / kg, 450m 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg, 500m 2 / kg, but not limited to this.

[0045] In an embodiment, the fiber length of the amino-modified polyacrylonitrile fiber is 10mm to 30mm. The use of the amino-modified polyacrylonitrile fiber with a fiber length of 10mm to 30mm can not only further improve the ability of the fiber to compete with soil particles for water, thereby further improving the speed of water evaporation in the over-wet soil, but also can better reduce the shrinkage of the soil body, thereby further improving the durability of the soil body.

[0046] Specifically, the fiber length of the amino-modified polyacrylonitrile fiber is exemplarily 10mm, 12mm, 15mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, but not limited to this.

[0047] More preferably, the mineral powder is S95 grade mineral powder, which has higher activity.

[0048] In an embodiment, the calcium hydroxide content in the carbide slag is greater than or equal to 85% by mass percentage, which can more effectively activate the activity of the mineral powder and enhance the early mechanical properties of the over-wet soil.

[0049] In an embodiment, the cement is Portland cement. The main components of the Portland cement are Portland cement clinker, admixture and gypsum. The components such as tricalcium silicate and dicalcium silicate in the Portland cement clinker will rapidly undergo hydration reaction after contacting with water, consume the water in the over-wet soil, and release heat energy, further accelerating the evaporation of water, thereby achieving a more efficient water reduction effect.

[0050] In an alternative embodiment of the present application, the Portland cement of PO425 type can be optionally used.

[0051] In an embodiment, the raw material of the amino-modified polyacrylonitrile fiber includes 15-30% of polyacrylonitrile fiber, 10-20% of ethylenediamine and 60-75% of water by mass percentage.

[0052] In an embodiment, the amino-modified polyacrylonitrile fiber is prepared by the following method:

[0053] a. mixing water and ethylenediamine to prepare an ethylenediamine solution;

[0054] b. immersing polyacrylonitrile fiber in the ethylenediamine solution to obtain a mixture;

[0055] c. heating the mixture to 60-80°C and maintaining the temperature for 10-14 hours of reflux, taking out the fiber and rinsing with clean water;

[0056] d. drying the rinsed fiber to obtain the amino-modified polyacrylonitrile fiber.

[0057] By hydrophilic modification of the polyacrylonitrile fiber, the prepared amino-modified polyacrylonitrile fiber can more effectively compete for water in the soil, reduce the binding effect of the soil on water, and thereby improve the water reduction rate of the over-wet soil.

[0058] More preferably, in the above step a, the water and the ethylenediamine are mixed under ice bath conditions to prepare the ethylenediamine solution.

[0059] More preferably, in the above step b, the polyacrylonitrile fiber needs to be completely immersed in the ethylenediamine solution.

[0060] More preferably, in the above step c, after the reflux is completed, the mixture is cooled to room temperature, and then the fiber is taken out and rinsed with clean water.

[0061] More preferably, in step d above, the rinsed fibers are dried at 40°C to 60°C for 10 to 16 hours to obtain amino-modified polyacrylonitrile fibers.

[0062] Accordingly, a method for preparing a wet soil precipitation solidification agent is also disclosed, which is used to prepare the above-mentioned wet soil precipitation solidification agent, including the following steps:

[0063] (1) Dry the cement, carbide slag and mineral powder separately, and then ball mill the dried cement and mineral powder separately.

[0064] (2) According to the ratio, the cement, carbide slag and mineral powder treated in step (1) are mixed evenly, and then amino-modified polyacrylonitrile fiber is added and mixed evenly to obtain the soil dewatering curing agent.

[0065] More preferably, in step (1), the cement, carbide slag, and mineral powder are placed in an oven at 100℃~110℃ for drying for ≥8h until the materials are completely dry. Subsequently, the dried carbide slag is stored in a sealed container for later use, and the dried cement and mineral powder are ball-milled separately, and the processed materials are stored in a sealed container for later use.

[0066] In one embodiment, in step (1), the conditions for ball milling the dried cement are as follows: ball milling time of 40-80 minutes, rotation speed of 400-600 r / min, and ball-to-material ratio of 3:1-5:1. Using this ball milling process ensures that the cement is fully ground, thereby effectively increasing the specific surface area of ​​the cement and controlling its specific surface area to around 400 m². 2 / kg~500m 2 / kg, which in turn promotes the hydration rate of cement and enhances its water-saving efficiency.

[0067] In one embodiment, the conditions for ball milling the dried mineral powder are as follows: ball milling time of 90–150 min, rotation speed of 400–600 r / min, and ball-to-material ratio of 3:1–5:1. Using this ball milling process ensures that the mineral powder is thoroughly ground and that its specific surface area is controlled at 450 m². 2 / kg~550m 2 / kg can effectively increase the reaction area and reaction rate of mineral powder, further improve the water absorption rate of the soil stabilizing agent and enhance the strength of the stabilized soil.

[0068] Accordingly, the embodiment also provides a method for dewatering over-wet soil, comprising the following steps: adding the over-wet soil dewatering curing agent into the over-wet soil and stirring uniformly, waiting for the water content of the over-wet soil to decrease, and collecting the subgrade filler when the water content of the over-wet soil decreases to a preset water content, wherein the over-wet soil dewatering curing agent is the over-wet soil dewatering curing agent described above. Preferably, the preset water content is the water content corresponding to a better compaction effect of the soil, so as to ensure the stability and bearing capacity of the subgrade after compaction. More preferably, the preset water content can be the optimum water content of the over-wet soil, which can be obtained by a compaction test.

[0069] The method for dewatering over-wet soil of the embodiment can realize the dewatering and curing effects of the over-wet soil by using the ball-milled cement and mineral powder in cooperation with the carbide slag and the amino-modified polyacrylonitrile fiber. In actual application, the over-wet soil dewatering curing agent is mixed with the over-wet soil in a certain proportion, and the originally large over-wet soil is gradually broken down into smaller particles as the stirring process continues. Under the combined action of the two dewatering mechanisms of hydration reaction and fiber heat release, the over-wet soil is successfully dewatered rapidly, and the subgrade filler can be collected when the water content decreases to the preset water content range. In subsequent use, the subgrade filler is compacted, and the remaining active ingredients in the over-wet soil dewatering curing agent form a gel-like network structure under the excitation of hydroxyl ions, filling the pores of the soil, thereby enhancing the bearing capacity and stability of the soil.

[0070] More preferably, the large over-wet soil is broken into small pieces, and then the over-wet soil dewatering curing agent is added to the over-wet soil, so as to further increase the contact area between the over-wet soil and the over-wet soil dewatering curing agent and further improve the dewatering efficiency.

[0071] In one embodiment, the water content of the over-wet soil is 20% to 45%, and the addition amount of the over-wet soil dewatering curing agent is 5% to 12% of the total mass of the over-wet soil when the over-wet soil is dewatered, which can achieve a better dewatering effect and requires a shorter time to reach the preset water content.

[0072] The technical solutions of the present application are further described below through examples and comparative examples.

[0073] Example 1

[0074] The over-wet soil dewatering curing agent of the embodiment comprises the following raw materials in the following mass percentages: cement 15.0%, carbide slag 20.0%, mineral powder 64.0%, and amino-modified polyacrylonitrile fiber 1.0%;

[0075] The specific surface area of the mineral powder is 490 m 2 The specific surface area of the cement is 450 m 2 / kg, the fiber length of the amino-modified polyacrylonitrile fiber is 20 mm, the content of calcium hydroxide in the carbide slag is 86%, and the cement is Portland cement.

[0076] The preparation method of the over-wet soil dewatering curing agent in the embodiment includes the following steps:

[0077] (1) The cement, carbide slag and mineral powder are respectively placed in an oven at 105°C for drying, and the drying is continuously heated for 8 hours. The dried cement and mineral powder are respectively subjected to ball milling treatment. The ball milling treatment of the dried cement is performed under the following conditions: ball milling time is 60 min, rotating speed is 500 r / min, and ball-to-material ratio is 3:1. The ball milling treatment of the dried mineral powder is performed under the following conditions: ball milling time is 110 min, rotating speed is 400 r / min, and ball-to-material ratio is 4:1.

[0078] (2) The water 62% and ethylenediamine 15% are slowly mixed under ice bath condition to prepare an ethylenediamine solution. The polyacrylonitrile fiber 23% is completely immersed in the ethylenediamine solution to obtain a mixture. The mixture is heated to 70°C and maintained at this temperature for refluxing for 12 hours, and then cooled to room temperature. The fiber is taken out and washed with clean water. The washed fiber is dried at 50°C for 12 hours to obtain the amino-modified polyacrylonitrile fiber.

[0079] (3) The cement, carbide slag and mineral powder treated in step (1) are put into a dry mixer in a proportioning manner and mixed. After uniform mixing, the amino-modified polyacrylonitrile fiber is added and fully stirred again to obtain the over-wet soil dewatering curing agent.

[0080] Example 2

[0081] The over-wet soil dewatering curing agent in the embodiment includes the following raw materials in the following mass percentages: cement 15.0%, carbide slag 25.0%, mineral powder 59.6% and amino-modified polyacrylonitrile fiber 0.4%. The cement, carbide slag, mineral powder and amino-modified polyacrylonitrile fiber used in the embodiment are the same as those in Example 1. The preparation method of the over-wet soil dewatering curing agent in the embodiment is the same as that in Example 1.

[0082] Example 3

[0083] The over-wet soil dewatering curing agent in the embodiment includes the following raw materials in the following mass percentages: cement 14.0%, carbide slag 23.0%, mineral powder 62.5% and amino-modified polyacrylonitrile fiber 0.5%. The cement, carbide slag, mineral powder and amino-modified polyacrylonitrile fiber used in the embodiment are the same as those in Example 1. The preparation method of the over-wet soil dewatering curing agent in the embodiment is the same as that in Example 1.

[0084] Example 4

[0085] The over-wet soil dewatering curing agent of the embodiment comprises the following raw materials in mass percentage: cement 20.0%, carbide slag 27.0%, mineral powder 52.4%, and amino-modified polyacrylonitrile fiber 0.6%, wherein the cement, carbide slag, mineral powder, and amino-modified polyacrylonitrile fiber used in the embodiment are the same as those in Embodiment 1; the preparation method of the over-wet soil dewatering curing agent of the embodiment is the same as that in Embodiment 1.

[0086] Embodiment 5

[0087] The over-wet soil dewatering curing agent of the embodiment comprises the following raw materials in mass percentage: cement 20.0%, carbide slag 27.0%, mineral powder 52.4%, and amino-modified polyacrylonitrile fiber 0.6%, wherein the cement, carbide slag, mineral powder, and amino-modified polyacrylonitrile fiber used in the embodiment are the same as those in Embodiment 1; the preparation method of the over-wet soil dewatering curing agent of the embodiment is the same as that in Embodiment 1.

[0088] Comparative Example 1

[0089] The over-wet soil dewatering curing agent of the comparative example comprises the following raw materials in mass percentage: cement 15.0%, carbide slag 20.0%, and mineral powder 65.0%, wherein the cement, carbide slag, and mineral powder used in the comparative example are the same as those in Embodiment 1.

[0090] The preparation method of the over-wet soil dewatering curing agent of the comparative example comprises the following steps:

[0091] (1) The cement, carbide slag, and mineral powder are respectively placed in an oven at 105°C for drying, and the drying is continuously performed for 8 hours. The dried cement and mineral powder are respectively subjected to ball milling treatment; wherein the ball milling treatment of the dried cement is performed under the following conditions: ball milling time is 60 min, rotating speed is 500 r / min, and ball-to-material ratio is 3:1; the ball milling treatment of the dried mineral powder is performed under the following conditions: ball milling time is 110 min, rotating speed is 400 r / min, and ball-to-material ratio is 4:1;

[0092] (2) The cement, carbide slag, and mineral powder treated in step (1) are put into a dry mixer according to the proportioning for mixing, and the over-wet soil dewatering curing agent is obtained after uniform mixing.

[0093] Performance test

[0094] The over-wet soil is taken, and the test shows that the water content of the over-wet soil is 30%. Part of the over-wet soil is taken for compaction test, and the optimum water content of the over-wet soil is 17% and the maximum dry density is 1.80 g / cm 3 .

[0095] Take 7 equal amounts of the above-mentioned over-wet soil samples, of which 5 are used as experimental groups, labeled A1, A2, A3, A4 and A5 respectively, and 2 are used as control groups, labeled B1 and B2 respectively. The experimental groups are added with the over-wet soil dewatering solidifying agents of Examples 1-5 respectively and stirred uniformly, and the addition amount of the over-wet soil dewatering solidifying agent is 8% (calculated based on the mass of the over-wet soil); the control group B1 is added with the over-wet soil dewatering solidifying agent of Comparative Example 1 and stirred uniformly, and the addition amount of the over-wet soil dewatering solidifying agent of Comparative Example 1 is 8% (calculated based on the mass of the over-wet soil), and the control group B2 is not added with any over-wet soil dewatering solidifying agent.

[0096] The above-mentioned A1, A2, A3, A4, A5, B1 and B2 are respectively placed in different open containers and placed in a constant temperature and humidity box (temperature: 20℃, humidity: 60%), the change of the soil temperature with time is recorded by a temperature sensor, and the maximum temperature and the duration of heat generation of the soil are recorded, and the change of the water content of the soil is measured and the time required to reach the optimum water content is recorded, and the results are shown in Table 1 below.

[0097] After the water content of the soil of A1, A2, A3, A4, A5, B1 and B2 is reduced to the optimum water content, the required amount for molding a single test piece is calculated according to the maximum dry density, and the required amount of the above-mentioned improved over-wet soil is weighed, and the above-mentioned improved over-wet soil is used to press into a cylindrical test piece with a diameter of 100mm and a height of 100mm using an oil press, and the obtained test piece is sealed in a bag and placed in standard curing conditions for curing until the required age is reached, and finally the over-wet soil solidified test piece is obtained. The over-wet soil solidified test pieces obtained from A1, A2, A3, A4, A5, B1 and B2 are respectively tested for unconfined compressive strength according to the "Inorganic Binder Test Procedure" (JTGE51-2009), and the test results are shown in Table 2 below.

[0098] Table 1 Related parameters of soil during dewatering process

[0099] Maximum temperature / °C Duration of heat generation / h Time required to reach optimum moisture content / h A1 29 9 38 A2 29 8 41 A3 28 7 43 A4 31 11 31 A5 30 10 35 B1 25 4 63 B2 20 0 210

[0100] From the experimental data in Table 1 above, it can be seen that in the absence of external conditions (B2), the dewatering efficiency of over-wet soil is extremely slow, and it takes 210h to reach the optimum water content. However, once the over-wet soil dewatering solidifying agent is added, the dewatering efficiency of over-wet soil can be significantly improved, because pure over-wet soil can only rely on evaporation to slowly release water in the soil to the surrounding environment, resulting in slow dewatering efficiency. After the addition of over-wet soil dewatering solidifying agent, the cementitious material components (cement, mineral powder) in the over-wet soil dewatering solidifying agent react with water to not only solidify the free water in the over-wet soil into bound water, but also release heat, promote the evaporation of water in the over-wet soil, and greatly improve the dewatering efficiency of the over-wet soil.

[0101] From the experimental data of A1-A5 in Table 1, it can also be found that, after introducing the amino-modified polyacrylonitrile fiber into the over-wet soil precipitation curing agent, compared with not introducing it (i.e. B1), the highest temperature and the duration of heat release of the whole system are improved, and the time required for the over-wet soil to reach the optimum water content is greatly shortened. This is because, after introducing the amino-modified polyacrylonitrile fiber, the free water in the over-wet soil combines with the hydrophilic groups on the fiber, and the water molecules change from a random motion state to a stationary state. According to the law of conservation of energy, the kinetic energy of the water molecules at this time is converted into heat energy, which is manifested as the release of heat by the amino-modified polyacrylonitrile fiber, further improving the overall temperature of the system. In addition, part of the evaporated water vapor is adsorbed on the amino-modified polyacrylonitrile fiber and changes from a gaseous state to a liquid state to release heat. Under the above two mechanisms, the highest temperature and the duration of heat release of the whole system are increased, thereby greatly improving the precipitation efficiency of the over-wet soil.

[0102] Table 2 Unconfined compressive strength test results

[0103] 7d unconfined compressive strength / MPa 28d unconfined compressive strength / MPa A1 1.7 2.9 A2 1.7 3.0 A3 1.6 2.8 A4 1.9 3.5 A5 1.8 3.3 B1 1.6 2.3 B2 0.3 0.4

[0104] As can be seen from the data in Table 2, the over-wet soil without adding any precipitation curing agent (i.e. B2) relies on the friction between soil particles for support after compaction, and this force is weak, resulting in a low unconfined compressive strength, and the strength does not develop significantly with time. When the precipitation curing agent is introduced, the self-hydration reaction of the residual cement after precipitation and the hydration reaction of the mineral powder under the excitation of the carbide slag produce a gel network in the system, filling the gaps between soil particles and forming a strength skeleton to support the soil body, so the unconfined compressive strength of B1 and A1-A5 is higher than that of the pure over-wet soil sample (i.e. B2). When the amino-modified polyacrylonitrile fiber is introduced (i.e. A1-A5), the fiber has a certain moisture absorption and water retention property, and will slowly release water over time, which is beneficial to prolonging the hydration reaction time and avoiding the mineral powder from stopping the reaction due to lack of water in the later stage. Therefore, the introduction of the amino-modified polyacrylonitrile fiber enables the mineral powder hydration reaction to proceed more completely, improving the compaction degree of the soil body in the later stage, which is specifically manifested as the unconfined compressive strength of the sample in the later stage being higher after introducing the amino-modified polyacrylonitrile fiber compared with the no-fiber group (i.e. B1).

[0105] The above only describes a preferred embodiment of the present application, and of course cannot limit the scope of the present application, and any equivalent changes made according to the claims of the present application are still within the scope of the present application.

Claims

1. A soil moisture-curing agent, characterized in that, The raw materials include the following percentages by weight: 10%–20% cement, 20%–30% carbide slag, 50%–69% mineral powder, and 0.1%–1% amino-modified polyacrylonitrile fiber; The amino-modified polyacrylonitrile fiber is a polyacrylonitrile fiber with amino groups introduced on its surface.

2. The soil dewatering and solidification agent according to claim 1, characterized in that, The specific surface area of ​​the mineral powder is 450 m². 2 / kg~550m 2 / kg; the specific surface area of ​​the cement is 400m². 2 / kg~500m 2 / kg.

3. The soil dewatering and solidification agent according to claim 1, characterized in that, The calcium hydroxide content in the carbide slag is ≥85% by mass percentage. The cement is silicate cement.

4. The soil dewatering and solidification agent according to claim 1, characterized in that, The amino-modified polyacrylonitrile fiber has a fiber length of 10 mm to 30 mm.

5. The soil dewatering and solidifying agent according to claim 1 or 4, characterized in that, The raw materials for the amino-modified polyacrylonitrile fiber, calculated by mass percentage, include 15%–30% polyacrylonitrile fiber, 10%–20% ethylenediamine, and 60%–75% water.

6. The soil dewatering and solidification agent according to claim 5, characterized in that, The amino-modified polyacrylonitrile fiber is prepared by the following method: An ethylenediamine solution was prepared by mixing water and ethylenediamine. Polyacrylonitrile fibers were immersed in an ethylenediamine solution to obtain a mixture; Heat the mixture to 60℃~80℃ and maintain the temperature under reflux for 10~14 hours. Remove the fibers and rinse them with clean water. The rinsed fibers are dried to obtain amino-modified polyacrylonitrile fibers.

7. A method for preparing a soil stabilizing agent for excessively wet soil, characterized in that, The preparation of the wet soil precipitation solidification agent according to any one of claims 1-6 comprises the following steps: (1) Dry the cement, carbide slag and mineral powder separately, and then ball mill the dried cement and mineral powder separately. (2) According to the ratio, the cement, carbide slag and mineral powder treated in step (1) are mixed evenly, and then amino-modified polyacrylonitrile fiber is added and mixed evenly to obtain the soil dewatering curing agent.

8. The preparation method of the soil water-stabilizing agent according to claim 7, characterized in that, In step (1), the conditions for ball milling the dried cement are as follows: ball milling time is 40 min to 80 min, rotation speed is 400 r / min to 600 r / min, and ball-to-material ratio is 3:1 to 5:1; The conditions for ball milling the dried mineral powder are as follows: ball milling time is 90 to 150 minutes, rotation speed is 400 to 600 r / min, and ball-to-material ratio is 3:1 to 5:

1.

9. The preparation method of the soil water-stabilizing agent according to claim 1, characterized in that, Before step (2), the method further includes a preparation step of amino-modified polyacrylonitrile fiber, wherein the preparation method of amino-modified polyacrylonitrile fiber includes the following steps: An ethylenediamine solution was prepared by mixing water and ethylenediamine. Polyacrylonitrile fibers were immersed in an ethylenediamine solution to obtain a mixture; Heat the mixture to 60℃~80℃ and maintain the temperature under reflux for 10~14 hours. Remove the fibers and rinse them with clean water. The rinsed fibers are dried to obtain amino-modified polyacrylonitrile fibers.

10. A method for dewatering excessively wet soil, characterized in that, The process includes the following steps: adding the wet soil dewatering and solidifying agent to the wet soil and stirring it evenly; waiting for the moisture content of the wet soil to decrease; when the moisture content of the wet soil decreases to the preset moisture content, the dewatering treatment of the wet soil is completed, and the roadbed fill material is collected; the wet soil dewatering and solidifying agent is the wet soil dewatering and solidifying agent as described in any one of claims 1-6.