Salinized soil reinforcing method, used soil stabilizer and preparation method

Abstract

The invention discloses a saline soil reinforcing method, a soil stabilizer and a preparation method, and belongs to the technical field of soil improvement and civil engineering materials, the soil stabilizer for saline soil reinforcing comprises a salt ion adsorbent, a cementation enhancer and a moisture regulator; the salt ion adsorbent is formed by compounding surface aminated attapulgite and aminated montmorillonite; the cementation enhancer is formed by compounding slag powder, desulfurized gypsum, metakaolin and a composite exciting agent, and the composite exciting agent is formed by mixing sodium hydroxide, sodium carbonate and sodium silicate; the moisture regulator is formed by compounding carboxyl modified polyacrylamide and carboxylated cellulose. When the saline soil is reinforced, impurities in the saline soil to be reinforced are removed, then the saline soil is aired, then the soil curing agent for saline soil reinforcement and water are added and evenly mixed, a mixture is obtained, the mixture is rolled into a compact forming body, then maintenance is conducted, soluble salt ions in the saline soil can be efficiently adsorbed, moisture migration is inhibited, and the bonding strength among soil particles is enhanced; the bearing strength, the water stability and the freeze-thaw resistance of the salinized soil are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement and civil engineering materials technology, specifically a method for reinforcing saline soil and the soil stabilizer and its preparation method. Background Technology

[0002] Saline soil is a general term for soils containing more than 0.5% soluble salts, widely distributed in coastal cities, Northwest China, and North China. The Cl- in saline soil... - SO4 2- Na + Soluble salt ions in saline soil are prone to dissolution, loss, or crystallization under wet-dry cycles or freeze-thaw cycles, leading to damage to the pore structure between soil particles. This results in high swelling and shrinkage rates when wetted and dry, low bearing strength, and poor water stability. This characteristic makes saline soil unsuitable for direct use as engineering foundation or road base material, requiring reinforcement treatment.

[0003] Existing saline soil reinforcement technologies are mainly divided into physical and chemical methods: physical methods (such as replacing sand and gravel, laying geotextiles) have high construction costs and high resource consumption, and cannot fundamentally solve the problem of expansion and contraction of saline soil; chemical methods mostly use lime, cement, and ordinary industrial waste as solidifying agents. Although they can improve short-term strength, they have two major drawbacks: first, they have a weak ability to fix salt ions, and long-term use will still lead to structural cracking and strength reduction due to salt ion migration; second, the interfacial adhesion between the solidifying agent and saline soil particles is poor, and they are easily eroded by water and delaminated, resulting in insufficient overall stability.

[0004] Furthermore, while some existing technologies incorporate functional components such as water-retaining agents and surfactants, they often employ single components or simple compound formulations. Some formulations also rely on special industrial waste (such as residual grout from square piles), making raw material supply highly geographically limited and hindering large-scale promotion. Additionally, a few technologies pose a risk of using toxic or hazardous chemicals, or involve large quantities and high costs of key functional components, which are detrimental to engineering applications.

[0005] Therefore, there is an urgent need to develop a soil stabilizer specifically for saline soil. Through multi-component synergistic design, it can achieve efficient fixation of salt ions in saline soil, precise control of moisture, and strong bonding of soil particle interfaces. At the same time, it should take into account the availability of raw materials, cost-effectiveness, and environmental safety, fundamentally solving the problems of long-term stability and engineering applicability of saline soil reinforcement. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for reinforcing saline soil, a soil stabilizer, and a preparation method. Through a synergistic system of salt ion adsorption, moisture regulation, and interface enhancement, it achieves efficient fixation of salt ions in saline soil, precise moisture regulation, and strong bonding of soil particles at the interface. At the same time, it takes into account the availability of raw materials, cost-effectiveness, and environmental safety, fundamentally solving the problems of long-term stability and engineering applicability of saline soil reinforcement.

[0007] This invention is achieved through the following technical solution: A soil stabilizer for reinforcing saline soil comprises a salt ion adsorbent, a cementing enhancer, and a moisture regulator in a mass ratio of (20-35):(50-70):(5-15). The salt ion adsorbent is a compound of surface-aminated attapulgite and aminated montmorillonite. The cementing and reinforcing agent is composed of slag powder, desulfurized gypsum, metakaolin and a composite activator. The composite activator is composed of sodium hydroxide, sodium carbonate and sodium silicate mixed in a mass ratio of (30-40):(20-30):(30-50). The moisture regulator is a compound of carboxyl-modified polyacrylamide and carboxylated cellulose in a mass ratio of (60-70):(30-40).

[0008] Preferably, the mass ratio of the surface-aminated attapulgite to the aminated montmorillonite is (60-80):(20-40).

[0009] Preferably, the surface-aminated attapulgite clay is obtained through the following process: Attapulgite is calcined at 600-650℃ for 2-3 hours, then sieved, and then 5-8% by mass of polyethyleneimine solution is added. The polyethyleneimine solution is 10-15% by mass of attapulgite. The mixture is stirred and reacted at 60-70℃ for 1.5-2 hours, dried and pulverized to obtain surface-aminated attapulgite. The aminated montmorillonite is obtained through the following process: Add 8-12% (by weight of montmorillonite) of 3-aminopropyltriethoxysilane to the montmorillonite suspension, reflux at 80-90℃ for 3-4 hours, then separate the product, wash, dry and pulverize it to obtain aminated montmorillonite.

[0010] Preferably, the mass ratio of the slag powder, desulfurized gypsum, metakaolin and composite activator is (40-55):(15-25):(10-20):(5-10).

[0011] Preferably, the slag powder has a specific surface area of ​​400-450 m² / kg, and the desulfurized gypsum has a moisture content of ≤10% and a particle size of less than 100 micrometers. The metakaolin is obtained by calcining kaolin at 700-750℃ for 2-3 hours, and has a specific surface area of ​​500-600m² / kg.

[0012] Preferably, the carboxyl-modified polyacrylamide is obtained by the following process: Add 5-8% (by weight of polyacrylamide) of maleic anhydride to an aqueous solution of polyacrylamide, stir and react at 50-60℃ for 2-3 hours, then filter the product, dry and pulverize it sequentially to obtain carboxyl-modified polyacrylamide.

[0013] Preferably, the carboxylated cellulose is obtained by the following process: Microcrystalline cellulose was soaked in sodium hydroxide solution at 30-40℃ for 1-2 hours, and then chloroacetic acid of 8-12% by weight of microcrystalline cellulose was added. The mixture was stirred at 50-60℃ for 3-4 hours. The pH of the resulting reaction solution was adjusted to neutral, and then filtered, washed, dried and pulverized in sequence to obtain carboxylated cellulose.

[0014] A method for preparing a soil stabilizer for reinforcing saline soil according to any one of the above-mentioned methods, comprising mixing the salt ion adsorbent, cementing enhancer and moisture regulator evenly to obtain the soil stabilizer for reinforcing saline soil.

[0015] A method for reinforcing saline soil involves removing impurities from the saline soil to be reinforced, drying it, adding a soil stabilizer for saline soil reinforcement and water, mixing them evenly to obtain a mixture, compacting the mixture into a dense mold, and then curing it to complete the reinforcement of the saline soil.

[0016] Preferably, the saline soil to be reinforced after removing impurities is dried until the moisture content is 15-20%, and the soil stabilizer and water used for the reinforcement of the saline soil account for 8-15% and 5-10% of the mass of the obtained saline soil, respectively.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a soil stabilizer for reinforcing saline soil. In this salt ion adsorbent, the surface-aminated attapulgite contains a large amount of amino groups (-NH2), which can adsorb Cl from the saline soil through electrostatic interactions. - SO4 2- Anions are present; the interlayer spacing of aminated montmorillonite is increased and amino functional groups are introduced, which not only adsorbs anions but also fixes Na+ through coordination. + K +The two are isocations, and when combined, they form a dual-adsorption-site system, which can efficiently fix soluble salt ions in saline soil, preventing their migration during wet-dry or freeze-thaw cycles and avoiding damage to the soil structure. The active components (such as SiO2, Al2O3, and CaSO4) in the cementitious reinforcing agent, slag powder, desulfurized gypsum, and metakaolin, undergo rapid hydration reactions under the action of composite activators (NaOH, Na2CO3, and Na2SiO3): NaOH and Na2CO3 disrupt the aluminosilicate network structure of the slag powder and metakaolin, releasing active SiO2 and Al2O3; Na2SiO3 provides additional SiO2, which reacts with Ca... 2+ The hydration products from desulfurized gypsum react to form CSH gel and CASH gel; CaSO4 in desulfurized gypsum reacts with aluminum phase hydration products to form AFt (ettringite), further filling the pores between soil particles. These hydration products are tightly bonded to soil particles, forming a continuous cemented skeleton, significantly improving the bearing capacity and structural stability of saline soil. The carboxyl-modified polyacrylamide in the moisture regulator introduces carboxyl groups (-COOH), enhancing its water absorption capacity and salt tolerance. It can adsorb and fix free water in saline soil, reducing salt ion dissolution caused by water migration; the carboxyl groups of carboxylated cellulose can form hydrogen bonds with the hydroxyl groups (-OH) on the surface of soil particles, and simultaneously physically encapsulate and chemically bind with the aforementioned hydration products (such as CSH gel), further locking in moisture and preventing volume expansion and contraction caused by wet-dry cycles. In addition, the polymer chains in the moisture regulator can form a bridging effect between soil particles, enhancing the cohesion between particles. It is suitable for the reinforcement treatment of various saline soils such as coastal saline soil and inland saline-alkali soil, and can be widely used in engineering scenarios such as road base, building foundation cushion, and slope protection in saline soil areas.

[0018] The soil stabilizer for reinforcing saline soil of the present invention can efficiently adsorb soluble salt ions in saline soil, inhibit water migration, and enhance the bonding strength between soil particles through the synergistic effect of multiple components in the salt ion adsorbent, cementing enhancer and moisture regulator, thus significantly improving the bearing capacity, water stability and freeze-thaw resistance of saline soil. At the same time, the raw materials of this stabilizer are readily available and inexpensive, and there are no toxic or harmful substances, making it suitable for large-scale engineering applications.

[0019] This invention discloses a method for reinforcing saline soil. First, the saline soil to be reinforced is cleaned of impurities and dried. Then, a soil stabilizer and water are added and mixed evenly. The resulting mixture is compacted into a dense, molded mass and then cured. The 28-day unconfined compressive strength is ≥1.65 MPa, far exceeding the strength requirement for saline soil subgrade in the "Highway Subgrade Design Specification" (≥0.8 MPa). The salt ion fixation rate is ≥84.5%, effectively inhibiting the expansion and contraction of saline soil due to wet and dry conditions. It exhibits excellent freeze-thaw resistance and water erosion resistance, meeting the engineering needs of cold and humid regions. This method is simple to operate, requires no complex equipment, and allows for flexible adjustment of the dosage based on the salinity of the soil and engineering requirements, adapting to different saline soil reinforcement scenarios. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0021] This invention discloses a soil stabilizer for reinforcing saline soil, wherein the soil stabilizer is composed of component A (salt ion adsorbent), component B (cementing enhancer), and component C (moisture regulator) mixed in a mass ratio of (20-35):(50-70):(5-15); wherein: Component A is a mixture of modified attapulgite and aminated montmorillonite in a mass ratio of (60-80):(20-40); The modified attapulgite is prepared as follows: attapulgite is calcined at 600-650℃ for 2-3 hours, cooled and passed through a 200-mesh sieve, and 10-15% (by mass) of a polyethyleneimine solution (mass percentage of 5-8%) is added. The mixture is stirred and reacted at 60-70℃ for 1.5-2 hours, vacuum dried (temperature 80-90℃, vacuum degree -0.08~-0.09MPa), and then pulverized to pass through a 300-mesh sieve. The vacuum degree of -0.09MPa means that the internal pressure is 0.09MPa lower than the atmospheric pressure, thus obtaining the modified attapulgite, i.e., surface-aminated attapulgite. The preparation method of the aminated montmorillonite is as follows: montmorillonite is added to deionized water and ultrasonically dispersed (power 300-400W, time 20-30 minutes) to prepare a suspension with a mass percentage of 5-8%. 8-12% of 3-aminopropyltriethoxysilane by mass of montmorillonite is added, and the mixture is refluxed at 80-90℃ for 3-4 hours. The mixture is then centrifuged (speed 3000-4000r / min, time 15-20 minutes). The precipitate is washed 3-5 times with deionized water until the washing solution is neutral. The washed precipitate is dried and then pulverized to pass through a 300-mesh sieve to obtain aminated montmorillonite.

[0022] Component B is composed of slag powder, desulfurized gypsum, metakaolin, and composite activator in a mass ratio of (40-55):(15-25):(10-20):(5-10). The slag powder is S95 grade granulated blast furnace slag powder with a specific surface area of ​​400-450 m² / kg. The desulfurized gypsum is industrial by-product desulfurized gypsum with a moisture content of ≤10%, passed through a 150-mesh sieve to make the particle size less than 100 micrometers. The metakaolin is calcined kaolin (calcination temperature 700-750℃, holding time 2-3 hours) with a specific surface area of ​​500-600 m² / kg. The composite activator is composed of sodium hydroxide, sodium carbonate, and sodium silicate in a mass ratio of (30-40):(20-30):(30-50), wherein the modulus of sodium silicate (molar ratio of SiO2 to Na2O) is 2.5-3.0.

[0023] Component C is a compound of modified polyacrylamide and carboxylated cellulose in a mass ratio of (60-70):(30-40); The modified polyacrylamide is prepared as follows: polyacrylamide (molecular weight 800-1000 million) is dissolved in deionized water to prepare a polyacrylamide solution with a mass percentage of 2-3%. Maleic anhydride with a mass percentage of 5-8% of polyacrylamide is added, and the mixture is stirred and reacted at 50-60℃ for 2-3 hours. Ethanol (volume 2-3 times the volume of the polyacrylamide solution) is added to precipitate the product. After filtration, the product is dried and pulverized to pass through a 200-mesh sieve to obtain modified polyacrylamide, namely carboxyl-modified polyacrylamide. The method for preparing the carboxylated cellulose is as follows: 1 kg of microcrystalline cellulose is added to 1 L of sodium hydroxide solution with a mass percentage of 10-15%, and soaked at 30-40°C for 1-2 hours. Then, 8-12% chloroacetic acid (by mass of microcrystalline cellulose) is added, and the mixture is stirred and reacted at 50-60°C for 3-4 hours. The pH is adjusted to neutral with hydrochloric acid, filtered, and washed with deionized water until no chloride ions are detected (no precipitate is detected by silver nitrate solution). The mixture is then dried, pulverized, and passed through a 200-mesh sieve to obtain carboxylated cellulose.

[0024] This invention discloses a method for reinforcing saline soil, comprising the following steps: Step 1. Pretreatment of saline soil Remove impurities (such as stones and plant roots) larger than 5mm from the saline soil to be reinforced, dry it until the moisture content is 15-20% (mass fraction), crush it and pass it through a 10-mesh sieve to obtain pretreated saline soil.

[0025] Step 2: Addition and mixing of curing agent Add the soil stabilizer described in this invention at 8-15% of the mass of the pretreated saline soil, and add water (5-10% of the mass of the pretreated saline soil). Mix with a forced mixer for 10-15 minutes to ensure that the stabilizer, saline soil, and water are mixed evenly to obtain a saline soil-stabilizer mixture.

[0026] Step 3: Shaping and Curing Fill the mold or construction area with the mixture of saline soil and solidifying agent, and compact it 3-5 times with a vibratory roller (excitation force 20-30kN) (let it stand for 5-10 minutes after each compaction) to form a dense molded body; then cure it for 7-28 days at a temperature of (20±5)℃ and relative humidity ≥85% to complete the reinforcement treatment of saline soil.

[0027] Example 1: Stabilizer and its application for slightly saline soil (soluble salt content 0.5-1.0%) I. Preparation of curing agent (I) Preparation of Component A (Salt Ion Adsorbent) Preparation of modified attapulgite soil Take 100 kg of attapulgite and place it in a muffle furnace. Calcinate it at 600℃ for 3 hours. After cooling, pass it through a 200-mesh sieve to obtain calcined attapulgite. Add 12 kg of a 6% (w / w) polyethyleneimine solution to the calcined attapulgite and transfer it to a reaction vessel. Stir and react at 65℃ for 1.8 hours. After the reaction is complete, place the material in a vacuum drying oven and dry it at 85℃ and a vacuum of -0.085 MPa for 4 hours. After pulverizing, pass it through a 300-mesh sieve to obtain modified attapulgite.

[0028] Preparation of aminated montmorillonite Take 40 kg of montmorillonite, add 800 L of deionized water, and ultrasonically disperse at 350 W for 25 minutes to prepare a 5% (w / w) montmorillonite suspension. Add 4 kg of 3-aminopropyltriethoxysilane to the suspension, transfer to a reflux reactor, and reflux at 85 °C for 3.5 hours. After the reaction, place the mixture in a centrifuge and centrifuge at 3500 r / min for 18 minutes to collect the precipitate. Wash the precipitate four times with 200 L of deionized water each time until the washing liquid is neutral. Dry the washed precipitate at 80 °C for 6 hours, pulverize it, and pass it through a 300-mesh sieve to obtain aminated montmorillonite.

[0029] Component A mixing: The modified attapulgite and aminated montmorillonite prepared above are added to a mixer at a mass ratio of 70:30 and stirred for 30 minutes. After being mixed evenly, component A (salt ion adsorbent) is obtained.

[0030] (II) Preparation of Component B (Cementing Reinforcing Agent) Raw material preparation 50 kg of S95 grade granulated blast furnace slag powder (specific surface area 420 m² / kg), 20 kg of industrial by-product desulfurization gypsum (moisture content 8%, passed through a 150-mesh sieve), and 18 kg of calcined kaolin (calcined at 720℃ for 2.5 hours, specific surface area 550 m² / kg) were selected. A composite activator was prepared according to a mass ratio of 3.5:2.5:4, namely, 3.5 kg of sodium hydroxide, 2.5 kg of sodium carbonate, and 4 kg of sodium silicate with a modulus of 2.8 were taken and mixed evenly to obtain the composite activator.

[0031] Component B mixture Slag powder, desulfurized gypsum, metakaolin and composite activator are put into a forced mixer and stirred for 45 minutes to ensure that each component is evenly dispersed, thus obtaining component B (cementing reinforcing agent).

[0032] (III) Preparation of Component C (Moisture Conditioner) Preparation of modified polyacrylamide: Take 60 kg of polyacrylamide (molecular weight 9 million), add 2700 L of deionized water, stir to dissolve, and prepare a polyacrylamide solution with a mass percentage of 2.2%; add 4 kg of maleic anhydride to the solution, stir and react at 55 °C for 2.5 hours; after the reaction is completed, add 5400 L of ethanol, stir and let stand for 30 minutes, filter and collect the precipitate; dry the precipitate at 75 °C for 5 hours, pulverize and pass through a 200 mesh sieve to obtain modified polyacrylamide.

[0033] Preparation of carboxylated cellulose: Take 30 kg of microcrystalline cellulose, add 300 L of 12% sodium hydroxide solution, and soak at 35 °C for 1.5 hours; add 3 kg of chloroacetic acid to the soaking solution, and stir at 55 °C for 3.5 hours; after the reaction, adjust the pH of the system to 7.0 with 10% hydrochloric acid, filter and collect the solid; wash the solid with deionized water until no chloride ions are formed (take 10 mL of washing liquid, add 1 mL of 0.1 mol / L silver nitrate solution, no white precipitate is formed); dry the washed solid at 80 °C for 6 hours, pulverize and pass through a 200 mesh sieve to obtain carboxylated cellulose.

[0034] Component C mixing: Modified polyacrylamide and carboxylated cellulose were added to a mixer at a mass ratio of 65:35 and stirred for 30 minutes. After being mixed evenly, component C (moisture regulator) was obtained.

[0035] (iv) Total mixture of curing agent Weigh out components A, B, and C in a mass ratio of 25:65:10, put them into a double helix mixer, stir for 60 minutes, mix evenly, and then package to obtain a solidifying agent suitable for slightly saline soil.

[0036] II. Application of Saline Soil Reinforcement Pretreatment of saline soil: Slightly saline soil from Yancheng City, Jiangsu Province (soluble salt content 0.8%, including Cl...) was used. - The content is 0.25%, SO4 2- 1000 kg of saline soil (containing 0.45% of the soil) was processed to remove impurities such as stones and plant roots with a particle size greater than 5 mm. The saline soil was dried until the moisture content was 18%, then crushed by a pulverizer and passed through a 10-mesh sieve to obtain pretreated saline soil.

[0037] Mixing and stirring: Add 80 kg of the prepared curing agent and 70 kg of water to the pretreated saline soil; put the material into a forced mixer and stir for 12 minutes to ensure that the curing agent, water and saline soil are fully mixed to obtain a saline soil-curing agent mixture.

[0038] Molding and curing: The mixture was filled into a 100mm×100mm×100mm cubic mold and rolled 4 times with a vibratory roller with an excitation force of 25kN. After each rolling, the mixture was allowed to stand for 8 minutes. After molding, the test blocks were placed in a standard curing chamber (temperature 20℃, relative humidity 90%) for curing. The performance indicators were measured at 7 days, 14 days, 28 days and 90 days.

[0039] III. Performance Test Results

[0040] Example 2: Stabilizer and its application for moderately saline soil (soluble salt content 1.0-2.0%) I. Preparation of curing agent (I) Preparation of Component A (Salt Ion Adsorbent) Preparation of modified attapulgite soil: Take 100 kg of attapulgite clay, calcine it at 630℃ for 2.5 hours, cool it and pass it through a 200-mesh sieve; add 15 kg of polyethyleneimine solution with a mass percentage of 8%, stir and react at 70℃ for 2 hours; vacuum dry (90℃, -0.09 MPa) for 3.5 hours, pulverize and pass it through a 300-mesh sieve to obtain modified attapulgite clay.

[0041] Preparation of aminated montmorillonite: Take 50 kg of montmorillonite, add 833 L of deionized water, and ultrasonically disperse at 400 W for 20 minutes to prepare a montmorillonite suspension with a mass percentage of 6%. Add 6 kg of 3-aminopropyltriethoxysilane to the suspension and reflux at 90 °C for 3 hours. Centrifuge at 4000 r / min for 15 minutes, wash the precipitate 4 times until the washing liquid is neutral, dry the washed precipitate, pulverize it and pass it through a 300 mesh sieve to obtain aminated montmorillonite.

[0042] Component A mixing: Modified attapulgite and aminated montmorillonite are mixed at a mass ratio of 65:35 and stirred for 35 minutes to obtain component A.

[0043] (II) Preparation of Component B (Cementing Reinforcing Agent) Raw material preparation: 45 kg of S95 grade granulated blast furnace slag powder (specific surface area 450 m² / kg), 25 kg of desulfurized gypsum (moisture content 9%), 15 kg of metakaolin (calcined at 750℃ for 2 hours, specific surface area 600 m² / kg); composite activator (4 kg of sodium hydroxide, 3 kg of sodium carbonate, 3 kg of sodium silicate, modulus 2.5).

[0044] Component B mixing: The above raw materials are put into a mixer and stirred for 50 minutes to obtain component B.

[0045] (III) Preparation of Component C (Moisture Conditioner) Preparation of modified polyacrylamide: 65 kg of polyacrylamide (10 million molecular weight) was added to 2955 L of water to prepare a polyacrylamide solution with a mass percentage of 2.1%; 5.2 kg of maleic anhydride was added to the solution and reacted at 60 °C for 2 hours; after the reaction was completed, 5950 L of ethanol was added, stirred and allowed to stand for 45 minutes, and the precipitate was collected by filtration; the precipitate was dried at 80 °C for 6 hours, pulverized and passed through a 200-mesh sieve to obtain modified polyacrylamide.

[0046] Preparation of carboxylated cellulose: 35 kg of microcrystalline cellulose was soaked in 350 L of 15% sodium hydroxide solution for 1 hour; 4.2 kg of chloroacetic acid was added and reacted at 60 °C for 3 hours; after the reaction, the pH of the system was adjusted to 7.0 with 10% hydrochloric acid solution, and the solid was collected by filtration; the solid was washed with deionized water until no chloride ions were formed (10 mL of washing solution was taken and 1 mL of 0.1 mol / L silver nitrate solution was added, and no white precipitate was formed); the washed solid was dried at 80 °C for 6 hours, pulverized and passed through a 200-mesh sieve to obtain carboxylated cellulose.

[0047] Component C mixing: Modified polyacrylamide and carboxylated cellulose were mixed at a mass ratio of 60:40 and stirred for 35 minutes to obtain component C.

[0048] (iv) Total mixture of curing agent Weigh components A, B, and C in a mass ratio of 30:60:10, and mix them in a twin-helix mixer for 70 minutes to obtain a solidifying agent suitable for moderately saline soil.

[0049] II. Application of Saline Soil Reinforcement Pretreatment of saline soil: Moderately saline soil (soluble salt content 1.5%, including Cl) was taken from Dongying City, Shandong Province. - The content is 0.42%, SO4 2- 1000 kg of a product with a moisture content of 0.78% was pretreated to a moisture content of 16%, then crushed using a pulverizer and passed through a 10-mesh sieve.

[0050] Mixing and stirring: Add 120kg of curing agent and 80kg of water to the pretreated saline soil, stir for 15 minutes to obtain the mixture.

[0051] Molding and curing: The mixture was filled into a 100mm×100mm×100mm cubic mold and rolled 5 times with a vibratory roller with an excitation force of 28kN. After each rolling, the mixture was allowed to stand for 10 minutes. After molding, the test blocks were placed in a standard curing chamber (22℃, 92% humidity) for curing. The performance indicators were measured at 7 days, 14 days, 28 days and 90 days.

[0052] III. Performance Test Results

[0053] Example 3: Stabilizer and its application for heavily saline soil (soluble salt content 2.0-3.0%) I. Preparation of curing agent (I) Preparation of Component A (Salt Ion Adsorbent) Preparation of modified attapulgite soil: 100 kg of attapulgite clay was calcined at 650℃ for 2 hours and passed through a 200-mesh sieve; 10 kg of a 5% polyethyleneimine solution was added and stirred at 60℃ for 1.5 hours; the mixture was then vacuum dried (80℃, -0.08 MPa) for 4.5 hours and pulverized through a 300-mesh sieve.

[0054] Preparation of aminated montmorillonite: 60 kg of montmorillonite was added to 1000 L of water and ultrasonically dispersed at 300 W for 30 minutes to prepare a montmorillonite suspension with a mass percentage of 6%. 7.2 kg of 3-aminopropyltriethoxysilane was added to the suspension and refluxed at 80 °C for 4 hours. The mixture was centrifuged at 3000 r / min for 20 minutes, and the precipitate was washed 5 times until the washing liquid was neutral. The washed precipitate was dried, pulverized, and passed through a 300 mesh sieve.

[0055] Component A mixing: Modified attapulgite and aminated montmorillonite are mixed at a mass ratio of 60:40 and stirred for 40 minutes to obtain component A.

[0056] (II) Preparation of Component B (Cementing Reinforcing Agent) Raw material preparation: 55 kg of S95 grade granulated blast furnace slag powder (specific surface area 400 m² / kg), 15 kg of desulfurized gypsum (moisture content 7%), 20 kg of metakaolin (calcined at 700℃ for 3 hours, specific surface area 500 m² / kg); composite activator (3 kg of sodium hydroxide, 2 kg of sodium carbonate, 5 kg of sodium silicate, modulus 3.0).

[0057] Component B mixing: The raw materials are put into a mixer and stirred for 55 minutes to obtain component B.

[0058] (III) Preparation of Component C (Moisture Conditioner) Preparation of modified polyacrylamide: 70 kg of polyacrylamide (8 million molecular weight) was added to 3333 L of water to make a polyacrylamide solution with a mass percentage of 2.0%; 3.5 kg of maleic anhydride was added to the solution and reacted at 50 °C for 3 hours; after the reaction was completed, 6680 L of ethanol was added, stirred and allowed to stand for 50 minutes, and the precipitate was collected by filtration; the precipitate was dried at 85 °C for 6 hours, pulverized and passed through a 200 mesh sieve.

[0059] Preparation of carboxylated cellulose: 40 kg of microcrystalline cellulose was soaked in 400 L of 10% sodium hydroxide solution for 2 hours; 3.2 kg of chloroacetic acid was added and reacted at 50 °C for 4 hours; after the reaction, the pH of the system was adjusted to 7.0 with 10% hydrochloric acid solution, and the solid was collected by filtration; the solid was washed with deionized water until no chloride ions were formed (10 mL of washing solution was taken and 1 mL of 0.1 mol / L silver nitrate solution was added, and no white precipitate was formed); the washed solid was dried at 80 °C for 6 hours and then pulverized through a 200-mesh sieve.

[0060] Component C mixing: Modified polyacrylamide and carboxylated cellulose were mixed at a mass ratio of 70:30 and stirred for 40 minutes to obtain component C.

[0061] (iv) Total mixture of curing agent Weigh components A, B, and C in a mass ratio of 35:55:10, and mix them in a twin-helix mixer for 80 minutes to obtain a solidifying agent suitable for heavily saline soil.

[0062] II. Application of Saline Soil Reinforcement Pretreatment of saline soil: Severely saline soil (soluble salt content 2.8%, including Cl) was taken from Karamay City, Xinjiang Uygur Autonomous Region. - The content is 0.85%, SO4 2- 1000 kg of a product with a content of 1.25% was pretreated to a moisture content of 15%, then crushed using a pulverizer and passed through a 10-mesh sieve.

[0063] Mixing and stirring: After crushing with a pulverizer, add 150kg of curing agent and 90kg of water, stir for 18 minutes to obtain a mixture.

[0064] Molding and curing: The mixture was filled into a 100mm×100mm×100mm cubic mold and rolled 5 times with a vibratory roller with an excitation force of 30kN. After each rolling, the mixture was allowed to stand for 10 minutes. After molding, the test blocks were placed in a standard curing chamber (18℃, 88% humidity) for curing. The performance indicators were measured at 7 days, 14 days, 28 days and 90 days.

[0065] III. Performance Test Results

[0066] Example Description Component compatibility: For saline soils with different salt contents, by adjusting the proportion of component A (salt ion adsorbent) (25% for light, 30% for medium, and 35% for heavy) and the total dosage of solidifying agent (8% for light, 12% for medium, and 15% for heavy), the salt ion adsorption capacity and bonding strength can be precisely matched, avoiding cost waste caused by over-treatment or performance defects caused by under-treatment.

[0067] Process controllability: During the preparation of each component, the calcination temperature (600-650℃), time (1.5-2 hours), and vacuum degree (-0.08~-0.09MPa) of the attapulgite are clearly defined to ensure performance stability during industrial production; conventional construction equipment (forced mixer, vibratory roller) is used in the application stage, eliminating the need for additional special equipment and reducing costs.

[0068] Superior performance: Compared with the data of light, medium and heavy saline soil reinforcement, the 28-day unconfined compressive strength is ≥1.65MPa, which is far higher than the strength requirement of saline soil subgrade in the "Highway Subgrade Design Code" (≥0.8MPa); the salt ion fixation rate is ≥84.5%, which effectively inhibits the expansion and contraction of saline soil when wet and dry; the freeze-thaw resistance and water erosion resistance are excellent, meeting the engineering needs of cold and humid areas.

Claims

1. A soil stabilizer for reinforcing saline soil, characterized in that, Includes salt ion adsorbents, cementing enhancers, and moisture regulators in a mass ratio of (20-35):(50-70):(5-15); The salt ion adsorbent is a compound of surface-aminated attapulgite and aminated montmorillonite. The cementing and reinforcing agent is composed of slag powder, desulfurized gypsum, metakaolin and a composite activator. The composite activator is composed of sodium hydroxide, sodium carbonate and sodium silicate mixed in a mass ratio of (30-40):(20-30):(30-50). The moisture regulator is a compound of carboxyl-modified polyacrylamide and carboxylated cellulose in a mass ratio of (60-70):(30-40).

2. The soil stabilizer for saline soil reinforcement according to claim 1, characterized in that, The mass ratio of the surface-aminated attapulgite to the aminated montmorillonite is (60-80):(20-40).

3. The soil stabilizer for saline soil reinforcement according to claim 1, characterized in that, The surface-aminated attapulgite clay is obtained through the following process: Attapulgite is calcined at 600-650℃ for 2-3 hours, then sieved, and then 5-8% by mass of polyethyleneimine solution is added. The polyethyleneimine solution is 10-15% by mass of attapulgite. The mixture is stirred and reacted at 60-70℃ for 1.5-2 hours, dried and pulverized to obtain surface-aminated attapulgite. The aminated montmorillonite is obtained through the following process: Add 8-12% (by weight of montmorillonite) of 3-aminopropyltriethoxysilane to the montmorillonite suspension, reflux at 80-90℃ for 3-4 hours, then separate the product, wash, dry and pulverize it to obtain aminated montmorillonite.

4. The soil stabilizer for saline soil reinforcement according to claim 1, characterized in that, The mass ratio of the slag powder, desulfurized gypsum, metakaolin and composite activator is (40-55):(15-25):(10-20):(5-10).

5. The soil stabilizer for reinforcing saline soil according to claim 1, characterized in that, The specific surface area of ​​the slag powder is 400-450 m² / kg, and the moisture content of the desulfurized gypsum is ≤10% and the particle size is less than 100 micrometers. The metakaolin is obtained by calcining kaolin at 700-750℃ for 2-3 hours, and has a specific surface area of ​​500-600m² / kg.

6. The soil stabilizer for reinforcing saline soil according to claim 1, characterized in that, The carboxyl-modified polyacrylamide is obtained through the following process: Add 5-8% (by weight of polyacrylamide) of maleic anhydride to an aqueous solution of polyacrylamide, stir and react at 50-60℃ for 2-3 hours, then filter the product, dry and pulverize it sequentially to obtain carboxyl-modified polyacrylamide.

7. The soil stabilizer for saline soil reinforcement according to claim 1, characterized in that, The carboxylated cellulose is obtained through the following process: Microcrystalline cellulose was soaked in sodium hydroxide solution at 30-40℃ for 1-2 hours, and then chloroacetic acid of 8-12% by weight of microcrystalline cellulose was added. The mixture was stirred at 50-60℃ for 3-4 hours. The pH of the resulting reaction solution was adjusted to neutral, and then filtered, washed, dried and pulverized in sequence to obtain carboxylated cellulose.

8. A method for preparing a soil stabilizer for saline soil reinforcement according to any one of claims 1 to 7, characterized in that, The salt ion adsorbent, cementing enhancer and moisture regulator are mixed evenly to obtain a soil stabilizer for saline soil reinforcement.

9. A method for reinforcing saline soil, characterized in that, After removing impurities from the saline soil to be reinforced and drying it, add the soil stabilizer for saline soil reinforcement as described in claim 8 and water and mix evenly to obtain a mixture. After the mixture is rolled into a dense molded body, it is cured to complete the reinforcement of the saline soil.

10. The method for reinforcing saline soil according to claim 9, characterized in that, After removing impurities, the saline soil to be reinforced is dried until the moisture content is 15-20%. The soil stabilizer and water used for the reinforcement of the saline soil are 8-15% and 5-10% of the mass of the obtained saline soil, respectively.

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