Low-carbon composite gelling solidifying agent for solidifying silt soft soil and preparation method thereof

Abstract

The application discloses a low-carbon composite cementing solidifying agent for solidifying silt soft soil and a preparation method thereof, and relates to the technical field of solidifying agents. The raw materials of the low-carbon composite cementing solidifying agent include activated steel slag, slag, alkali activator, fiber reinforced component, desulfurization ash, desulfurization gypsum, cement and butadiene styrene latex solution; the activated steel slag is obtained by hot stewing, rod grinding, magnetic separation and powder grinding of liquid converter steel slag in a steel production process; the fiber reinforced component is obtained by pretreating hemp fibers, bamboo fibers and basalt fibers respectively and then mixing the hemp fibers, the bamboo fibers and the basalt fibers; and the alkali activator is obtained by mixing sodium carbonate, calcium hydroxide and nano aluminum oxide. The preparation method of the low-carbon composite cementing solidifying agent comprises the steps of preparing the fiber reinforced component, pretreating the steel slag and preparing the low-carbon composite cementing solidifying agent. The low-carbon composite cementing solidifying agent prepared by the application can effectively enhance the mechanical properties, freeze-thaw cycle resistance and water stability of silt solidifying soil.

Description

Technical Field

[0001] This invention relates to the field of curing agent technology, specifically to a low-carbon composite cementitious curing agent for curing silt and soft soil and its preparation method. Background Technology

[0002] Silt and soft soil, as widely distributed poor foundation soils, suffer from high water content, high void ratio, low strength, and high compressibility, which severely restrict the safety and efficiency of engineering construction. Solidification treatment is a key means to realize its engineering utilization. Currently, solidification of silt and soft soil mainly relies on traditional cementitious materials such as cement and lime. Although this can improve strength, the cement production process has high carbon emissions, which contradicts the "dual carbon" target. Moreover, the solidified soil is brittle and has poor crack resistance, and its strength is easily reduced by wet-dry cycles or freeze-thaw cycles. To reduce carbon emissions, alkali-activated solidifying agents based on industrial waste residues (such as steel slag and blast furnace slag) are gradually being used. However, when used alone, they have problems such as insufficient early strength and poor system stability. Especially when used in silt with high water content, the solidified body structure is loose due to insufficient hydration reaction, and its resistance to freeze-thaw cycles and water stability cannot meet engineering requirements.

[0003] Prior art disclosed in CN118026634A is a low-carbon composite cementitious solidifying agent and its solidification method for solidifying silty soft soil. This prior art mainly relies on the hydration and condensation reaction of steel slag and blast furnace slag to generate CSH and Si-O-Al gels to improve strength. However, the solidified body has insufficient stability, poor resistance to freeze-thaw cycles, and poor water stability, especially in high-moisture silty environments where water stability is difficult to meet engineering requirements. Prior art disclosed in CN117510111A is a solidifying agent for in-situ solidification of high-moisture silty soft soil. This prior art has limited strength improvement, high brittleness, insufficient resistance to freeze-thaw cycles and water stability, and a high proportion of sulfoaluminate cement (30%-70%), which does not conform to the low-carbon concept.

[0004] In summary, although the existing technical solutions have improved some properties of gelling and curing agents to a certain extent, the following technical problems still exist: they cannot effectively enhance the mechanical properties, freeze-thaw cycle resistance, and water stability of silt-stabilized soil. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a low-carbon composite cementitious curing agent for solidifying silt and soft soil and its preparation method, and achieves the following objectives: the prepared low-carbon composite cementitious curing agent can effectively enhance the mechanical properties, freeze-thaw cycle resistance, and water stability of solidified silt and soil.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A low-carbon composite cementitious solidifying agent for solidifying silt and soft soil, comprising the following raw materials by weight: 20-30 parts activated steel slag, 25-35 parts blast furnace slag, 6-8 parts alkali activator, 1.5-2 parts fiber reinforcement component, 10-15 parts desulfurization ash, 6-8 parts desulfurization gypsum, 3-6 parts cement, and 3-5 parts styrene-butadiene latex solution.

[0008] The activated steel slag is obtained by hot curing, rod milling, magnetic separation, and grinding of liquid converter steel slag in the steel production process.

[0009] The fiber reinforcement component is obtained by pretreating hemp fiber, bamboo fiber, and basalt fiber separately and then mixing them.

[0010] The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide and nano alumina, with the mass ratio of sodium carbonate, calcium hydroxide and nano alumina being (4-6):(2-3):1.

[0011] This invention also provides a method for preparing a low-carbon composite cementitious solidifying agent for solidifying silt and soft soil, comprising the following steps:

[0012] Step 1: Preparation of fiber reinforcement components

[0013] (1) Pretreatment of hemp fiber and bamboo fiber

[0014] The dried hemp fibers are immersed in NaOH solution at room temperature for 4-5 hours. After immersion, they are rinsed with deionized water until neutral, and then dried at 80-90℃ for 2-3 hours. After drying, they are immersed in silane diluent at room temperature for 1-2 hours. After immersion, they are dried at 80-90℃ for 2-3 hours to obtain pretreated hemp fibers.

[0015] The dried bamboo fiber is immersed in NaOH solution at room temperature for 4-5 hours. After immersion, it is rinsed with deionized water until neutral, and then dried at 80-90℃ for 2-3 hours. After drying, it is immersed in silane diluent at room temperature for 1-2 hours. After immersion, it is dried at 80-90℃ for 2-3 hours to obtain pretreated bamboo fiber.

[0016] The silane diluent is a 0.5-1% (w / w) silane coupling agent ethanol solution, and the silane coupling agent is KH-550; the NaOH solution is a 5%-10% (w / w) NaOH aqueous solution.

[0017] (2) Basalt fiber pretreatment

[0018] Basalt fibers are immersed in a silane solution and ultrasonically treated for 30-40 minutes at a power of 300-400W. After ultrasonic treatment, the fibers are removed and drained. Cement slurry is then sprayed onto the surface of the basalt fibers, with the amount of cement slurry being 5-10% of the weight of the basalt fibers. After spraying, the fibers are dried at a temperature of 60-70℃ for 2-3 hours to obtain pretreated basalt fibers.

[0019] The silane solution is an aqueous solution of silane coupling agent with a mass fraction of 1-1.2%, and the silane coupling agent selected is KH-570; the water-cement ratio of the cement paste is 0.5-0.6, and the cement selected is ordinary Portland cement P.O42.5.

[0020] (3) Formulating fiber reinforcement components

[0021] Pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber were added to a high-speed mixer at a speed of 300-500 rpm and stirred for 2-3 minutes to obtain the fiber reinforcing component. The mass ratio of the pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber was (4-5):(2-3):(2-3).

[0022] Step 2: Steel Slag Pretreatment

[0023] The steel slag is then cured by injecting hot water at 70-80℃ into the bottom of the curing tank, with the hot water flowing at a rate of 5-8m. 3 The flow rate is continuously circulated at / h, and the slag is simmered for 5-6 hours. After simmering, the steel slag is crushed by a rod mill at a speed of 10-20 rpm for 30-40 minutes. After crushing, magnetic separation is performed to remove impurities at a drum speed of 10-20 rpm for 30-40 minutes. After magnetic separation, grinding is performed at a speed of 400-500 rpm for 30-40 minutes to obtain activated steel slag.

[0024] Step 3: Prepare low-carbon composite gelling and curing agent

[0025] Add activated steel slag, blast furnace slag, and alkali activator to a twin-shaft mixer at a speed of 200-300 rpm for 10-15 minutes; add fiber reinforcement components and continue mixing for 10-15 minutes; add desulfurized gypsum and desulfurized ash, increase the speed to 400-500 rpm, and mix for 10-20 minutes; add styrene-butadiene latex solution, increase the speed to 500-600 rpm, and mix for 8-10 minutes to obtain a mixture; evenly spread cement on the surface of the mixture at a speed of 100-200 rpm and mix for 6-10 minutes to obtain a low-carbon composite gelling agent.

[0026] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) The low-carbon composite cementitious solidifier for solidifying silt and soft soil of the present invention can effectively enhance the mechanical properties of the solidified silt soil. The cementitious solidifier prepared by the present invention is used as a raw material, and the 7-day unconfined compressive strength of the solidified silt soil is 2.12-2.27 MPa, and the 28-day unconfined compressive strength is 3.57-3.81 MPa.

[0029] (2) The low-carbon composite cementitious solidifier for solidifying silt and soft soil of the present invention can effectively enhance the freeze-thaw cycle resistance of solidified silt soil. The cementitious solidifier prepared by the present invention is used as a raw material. After 25 freeze-thaw cycles, the mass loss rate of the solidified silt soil is 1.82-1.94%, and the unconfined compressive strength loss rate is 8.7-10.4%.

[0030] (3) The low-carbon composite cementitious solidifier for solidifying silt and soft soil of the present invention can effectively enhance the water stability of the solidified silt soil. Using the cementitious solidifier prepared by the present invention as a raw material, the silt solidified soil prepared by the present invention has an unconfined compressive strength loss rate of 2.5-3.8% after soaking for 24 hours. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. In the embodiments of the present invention, the steel slag is liquid converter steel slag from the steel production process, and its composition includes: CaO 30-32%, Fe2O3 28-29%, SiO2 16-17%, Al2O3 8-9%, MgO 6-7%. The slag composition includes: CaO 44-45%, SiO2 29-30%, Al2O3 14-15%, MgO 7-8%, SiO3 1-1.5%. The desulfurized gypsum composition includes: CaO 45-47%, SiO2 1-2%, Al2O3 0.5-1%, MgO 0.3-0.5%, SO3 50-52%, K2O 0.3-0.5%; the desulfurized gypsum particle size is 10-40 μm. The composition of desulfurization ash includes: SiO2 50-51%, Al2O3 36-38%, CaO 4-4.5%, SO3 2-2.5%; the particle size of desulfurization ash is 20-30μm.

[0032] Example 1: A low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil and its preparation method

[0033] A low-carbon composite gelling and curing agent for solidifying silt and soft soil, by weight, comprises the following raw materials: 20 parts activated steel slag, 35 parts slag, 6 parts alkali activator, 1.5 parts fiber reinforcement component, 10 parts desulfurization ash, 8 parts desulfurization gypsum, 6 parts cement, and 3 parts styrene-butadiene latex solution.

[0034] The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide, and nano-alumina, with a mass ratio of sodium carbonate, calcium hydroxide, and nano-alumina of 4:3:1.

[0035] The cement is slag silicate cement P.S32.5.

[0036] A method for preparing a low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil includes the following steps:

[0037] Step 1: Preparation of fiber reinforcement components

[0038] (1) Pretreatment of hemp fiber and bamboo fiber

[0039] The dried hemp fibers were immersed in NaOH solution and soaked at room temperature for 4 hours. After soaking, they were rinsed with deionized water until neutral, and then dried at 80°C for 3 hours. After drying, they were immersed in silane diluent and soaked at room temperature for 1 hour. After soaking, they were dried at 80°C for 3 hours to obtain pretreated hemp fibers.

[0040] The dried bamboo fiber was immersed in NaOH solution and soaked at room temperature for 4 hours. After soaking, it was rinsed with deionized water until neutral and then dried at 80℃ for 3 hours. After drying, it was immersed in silane diluent and soaked at room temperature for 1 hour. After soaking, it was dried at 80℃ for 3 hours to obtain pretreated bamboo fiber.

[0041] The hemp fiber has a length of 6-15 mm and a diameter of 10-30 μm; the bamboo fiber has a length of 8-20 mm and a diameter of 20-50 μm; the silane diluent is a 0.5-1% (w / w) silane coupling agent ethanol solution, and the silane coupling agent is KH-550; the NaOH solution is a 5%-10% (w / w) NaOH aqueous solution.

[0042] (2) Basalt fiber pretreatment

[0043] Basalt fibers were immersed in a silane solution and ultrasonically treated for 30 minutes at a power of 400W. After ultrasonic treatment, the fibers were removed and drained. Cement slurry was then sprayed onto the surface of the basalt fibers, with the amount of cement slurry being 5% of the mass of the basalt fibers. After spraying, the fibers were dried at 60℃ for 3 hours to obtain pretreated basalt fibers.

[0044] The basalt fibers are 5-12 mm in length and 10-20 μm in diameter; the silane solution is an aqueous solution of silane coupling agent with a mass fraction of 1-1.2%, and the silane coupling agent is KH-570; the cement paste has a water-cement ratio of 0.5-0.6, and the cement is ordinary Portland cement P.O42.5.

[0045] (3) Formulating fiber reinforcement components

[0046] Pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber were added to a high-speed mixer and stirred at 300 rpm for 3 minutes to obtain the fiber-reinforcing component. The mass ratio of the pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber was 4:2:2.

[0047] Step 2: Steel Slag Pretreatment

[0048] The steel slag is slag-curing, with 70°C hot water injected into the bottom of the curing tank at a flow rate of 8m. 3 The flow rate is continuously circulated at / h, and the slag simmering time is 6h. The slag after hot simmering is crushed by a rod mill at a speed of 10rpm for 40min. After crushing, magnetic separation is performed to remove impurities at a drum speed of 10rpm for 40min. After magnetic separation, grinding is performed at a speed of 400rpm for 40min to obtain activated steel slag.

[0049] Step 3: Prepare low-carbon composite gelling and curing agent

[0050] Activated steel slag, blast furnace slag, and alkali activator were added to a twin-shaft mixer at 200 rpm for 15 minutes. Fiber-reinforced components were added, and mixing continued for 15 minutes. Desulfurized gypsum and desulfurized ash were added, and the mixing speed was increased to 400 rpm for 20 minutes. Styrene-butadiene latex solution was added, and the mixing speed was increased to 500 rpm for 10 minutes to obtain a mixture. Cement was evenly spread on the surface of the mixture at 100 rpm for 10 minutes to obtain a low-carbon composite gelling agent.

[0051] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s.

[0052] Example 2: A low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil and its preparation method

[0053] A low-carbon composite gelling and curing agent for solidifying silt and soft soil, comprising the following raw materials by weight: 25 parts activated steel slag, 30 parts slag, 7 parts alkali activator, 2 parts fiber reinforcing component, 10 parts desulfurization ash, 7 parts desulfurization gypsum, 5 parts cement, and 5 parts styrene-butadiene latex solution.

[0054] The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide, and nano-alumina, with a mass ratio of sodium carbonate, calcium hydroxide, and nano-alumina of 5:3:1.

[0055] The cement is slag silicate cement P.S32.5.

[0056] A method for preparing a low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil includes the following steps:

[0057] Step 1: Preparation of fiber reinforcement components

[0058] (1) Pretreatment of hemp fiber and bamboo fiber

[0059] The dried hemp fibers were immersed in NaOH solution and soaked at room temperature for 5 hours. After soaking, they were rinsed with deionized water until neutral and then dried at 85°C for 3 hours. After drying, they were immersed in silane diluent and soaked at room temperature for 2 hours. After soaking, they were dried at 85°C for 3 hours to obtain pretreated hemp fibers.

[0060] The dried bamboo fiber was immersed in NaOH solution and soaked at room temperature for 5 hours. After soaking, it was rinsed with deionized water until neutral and then dried at 85°C for 3 hours. After drying, it was immersed in silane diluent and soaked at room temperature for 2 hours. After soaking, it was dried at 85°C for 3 hours to obtain pretreated bamboo fiber.

[0061] The hemp fiber has a length of 6-15 mm and a diameter of 10-30 μm; the bamboo fiber has a length of 8-20 mm and a diameter of 20-50 μm; the silane diluent is a 0.5-1% (w / w) silane coupling agent ethanol solution, and the silane coupling agent is KH-550; the NaOH solution is a 5%-10% (w / w) NaOH aqueous solution.

[0062] (2) Basalt fiber pretreatment

[0063] Basalt fibers were immersed in a silane solution and ultrasonically treated for 40 minutes at a power of 300W. After ultrasonic treatment, the fibers were drained and then coated with cement slurry, with the amount of cement slurry being 8% of the mass of the basalt fibers. After coating, the fibers were dried at 70°C for 3 hours to obtain pretreated basalt fibers.

[0064] The basalt fibers are 5-12 mm in length and 10-20 μm in diameter; the silane solution is an aqueous solution of silane coupling agent with a mass fraction of 1-1.2%, and the silane coupling agent is KH-570; the cement paste has a water-cement ratio of 0.5-0.6, and the cement is ordinary Portland cement P.O42.5.

[0065] (3) Formulating fiber reinforcement components

[0066] Pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber were added to a high-speed mixer and stirred at 400 rpm for 3 minutes to obtain the fiber-reinforcing component. The mass ratio of the pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber was 5:3:3.

[0067] Step 2: Steel Slag Pretreatment

[0068] The steel slag is slag-curing, with 80°C hot water injected into the bottom of the curing tank at a flow rate of 8m. 3 The flow rate is continuously circulated at / h, and the slag simmering time is 6h. After hot simmering, the steel slag is crushed by a rod mill at a speed of 20rpm for 40min. After crushing, magnetic separation is performed to remove impurities at a drum speed of 20rpm for 40min. After magnetic separation, grinding is performed at a speed of 500rpm for 40min to obtain activated steel slag.

[0069] Step 3: Prepare low-carbon composite gelling and curing agent

[0070] Activated steel slag, blast furnace slag, and alkali activator were added to a twin-shaft mixer at 300 rpm for 15 minutes. Fiber-reinforced components were added, and mixing continued for 15 minutes. Desulfurized gypsum and desulfurized ash were added, and the mixing speed was increased to 400 rpm for 20 minutes. Styrene-butadiene latex solution was added, and the mixing speed was increased to 500 rpm for 10 minutes to obtain a mixture. Cement was evenly spread on the surface of the mixture at 100 rpm for 10 minutes to obtain a low-carbon composite gelling agent.

[0071] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s.

[0072] Example 3: A low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil and its preparation method

[0073] A low-carbon composite gelling and curing agent for solidifying silt and soft soil, comprising the following raw materials by weight: 30 parts activated steel slag, 25 parts slag, 8 parts alkali activator, 2 parts fiber reinforcing component, 15 parts desulfurization ash, 6 parts desulfurization gypsum, 3 parts cement, and 5 parts styrene-butadiene latex solution.

[0074] The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide, and nano-alumina, with a mass ratio of sodium carbonate, calcium hydroxide, and nano-alumina of 6:2:1.

[0075] The cement is slag silicate cement P.S32.5.

[0076] A method for preparing a low-carbon composite cementitious solidifying agent for stabilizing silt and soft soil includes the following steps:

[0077] Step 1: Preparation of fiber reinforcement components

[0078] (1) Pretreatment of hemp fiber and bamboo fiber

[0079] The dried hemp fibers were immersed in NaOH solution and soaked at room temperature for 5 hours. After soaking, they were rinsed with deionized water until neutral, and then dried at 90°C for 2 hours. After drying, they were immersed in silane diluent and soaked at room temperature for 2 hours. After soaking, they were dried at 90°C for 2 hours to obtain pretreated hemp fibers.

[0080] The dried bamboo fiber was immersed in NaOH solution and soaked at room temperature for 5 hours. After soaking, it was rinsed with deionized water until neutral, and then dried at 90℃ for 2 hours. After drying, it was immersed in silane diluent and soaked at room temperature for 2 hours. After soaking, it was dried at 90℃ for 2 hours to obtain pretreated bamboo fiber.

[0081] The hemp fiber has a length of 6-15 mm and a diameter of 10-30 μm; the bamboo fiber has a length of 8-20 mm and a diameter of 20-50 μm; the silane diluent is a 0.5-1% (w / w) silane coupling agent ethanol solution, and the silane coupling agent is KH-550; the NaOH solution is a 5%-10% (w / w) NaOH aqueous solution.

[0082] (2) Basalt fiber pretreatment

[0083] Basalt fibers were immersed in a silane solution and ultrasonically treated for 40 minutes at a power of 300W. After ultrasonic treatment, the fibers were removed and drained. Cement slurry was then sprayed onto the surface of the basalt fibers, with the amount of cement slurry being 10% of the mass of the basalt fibers. After spraying, the fibers were dried at 70℃ for 2 hours to obtain pretreated basalt fibers.

[0084] The basalt fibers are 5-12 mm in length and 10-20 μm in diameter; the silane solution is an aqueous solution of silane coupling agent with a mass fraction of 1-1.2%, and the silane coupling agent is KH-570; the cement paste has a water-cement ratio of 0.5-0.6, and the cement is ordinary Portland cement P.O42.5.

[0085] (3) Formulating fiber reinforcement components

[0086] Pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber were added to a high-speed mixer at 500 rpm and stirred for 2 minutes to obtain the fiber-reinforcing component. The mass ratio of the pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber was 5:3:3.

[0087] Step 2: Steel Slag Pretreatment

[0088] The steel slag is slag-curing, with 80°C hot water injected into the bottom of the curing tank, and the hot water flowing at a rate of 5m. 3 The flow rate is continuously circulated at / h, and the slag simmering time is 5h. After simmering, the steel slag is crushed by a rod mill at a speed of 20rpm for 30min. After crushing, magnetic separation is performed to remove impurities at a drum speed of 20rpm for 30min. After magnetic separation, grinding is performed at a speed of 500rpm for 30min to obtain activated steel slag.

[0089] Step 3: Prepare low-carbon composite gelling and curing agent

[0090] Activated steel slag, blast furnace slag, and alkali activator were added to a twin-shaft mixer at 300 rpm for 10 minutes. Fiber-reinforced components were added and mixing continued for 10 minutes. Desulfurized gypsum and desulfurized ash were added, and the mixing speed was increased to 500 rpm for 10 minutes. Styrene-butadiene latex solution was added, and the mixing speed was increased to 600 rpm for 8 minutes to obtain a mixture. Cement was evenly spread on the surface of the mixture and stirred at 200 rpm for 6 minutes to obtain a low-carbon composite gelling agent.

[0091] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s. Comparative Example 1

[0092] A gelling and curing agent, by weight, comprises the following raw materials: 25 parts activated steel slag, 30 parts blast furnace slag, 7 parts alkali activator, 10 parts desulfurization ash, 7 parts desulfurization gypsum, 5 parts cement, and 5 parts styrene-butadiene latex solution.

[0093] The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide, and nano-alumina, with a mass ratio of sodium carbonate, calcium hydroxide, and nano-alumina of 5:3:1.

[0094] The cement is slag silicate cement P.S32.5.

[0095] A method for preparing a gelling and curing agent includes the following steps:

[0096] Step 1: Steel Slag Pretreatment

[0097] This step is the same as the "steel slag pretreatment" step in Example 2.

[0098] Step 2: Prepare the gelling and curing agent

[0099] Activated steel slag, blast furnace slag, and alkali activator were added to a twin-shaft mixer at 300 rpm for 15 minutes. Desulfurized gypsum and desulfurized ash were added, and the speed was increased to 400 rpm for 20 minutes. Styrene-butadiene latex solution was added, and the speed was increased to 500 rpm for 10 minutes to obtain a mixture. Cement was evenly spread on the surface of the mixture and stirred at 100 rpm for 10 minutes to obtain a gelling agent.

[0100] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s. Comparative Example 2

[0101] A gelling and curing agent, by weight, comprises the following raw materials: 25 parts activated steel slag, 30 parts blast furnace slag, 2 parts fiber reinforcing component, 10 parts desulfurization ash, 7 parts desulfurization gypsum, 5 parts cement, and 5 parts styrene-butadiene latex solution.

[0102] The cement is slag silicate cement P.S32.5.

[0103] A method for preparing a gelling and curing agent includes the following steps:

[0104] Step 1: Preparation of fiber reinforcement components

[0105] This step is the same as the step in Example 2, "Preparation of Fiber Reinforcing Component".

[0106] Step 2: Steel Slag Pretreatment

[0107] This step is the same as the "steel slag pretreatment" step in Example 2.

[0108] Step 3: Obtaining the gelling and curing agent

[0109] Activated steel slag, blast furnace slag, and fiber-reinforced components were added to a twin-shaft mixer at 300 rpm for 15 minutes. Desulfurized gypsum and desulfurized ash were added, and the speed was increased to 400 rpm for 20 minutes. Styrene-butadiene latex solution was added, and the speed was increased to 500 rpm for 10 minutes to obtain a mixture. Cement was evenly spread on the surface of the mixture and stirred at 100 rpm for 10 minutes to obtain a gelling agent.

[0110] The styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex with deionized water at a mass ratio of 1:1; the viscosity of the styrene-butadiene latex is ≤300 mPa·s.

[0111] Example 4 Performance Testing

[0112] (I) The gelling agents prepared in Examples 1-3 and Comparative Examples 1-2 were mixed with silt and soft soil to prepare a solidified soil mixture. Unconfined compressive strength tests were conducted according to the test method provided in JTG E51-2009. Specific test results are shown in Table 1. Sample preparation: The gelling agent and silt and soft soil were added to a mixer. The amount of gelling agent was 15% of the mass of the dry silt and soft soil. The mixing speed was 200 rpm, and the mixing time was 10 min. Then, water was added and stirred. The water content was 10-20% of the mass of the gelling agent. The mixing speed was 300 rpm, and the mixing time was 5 min, resulting in solidified silt soil. A cylindrical mold with dimensions of φ100mm×100mm was selected. The silt-stabilized soil was added to the mold, compacted by tamping and vibrating on a vibrating table, and then covered with a plastic film. The specimen and mold were placed in a standard constant temperature and humidity curing chamber at a curing temperature of 20±1℃ and a curing humidity of ≥95% for 48 hours. After curing, the specimen was demolded, wrapped and sealed with plastic film, and then placed back in the curing chamber to cure for the specified age. The natural moisture content of the silt-soft soil was 50-60%.

[0113] Table 1

[0114] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 7-day unconfined compressive strength (MPa) 2.18 2.27 2.12 1.67 1.34 28-day unconfined compressive strength (MPa) 3.64 3.81 3.57 2.76 2.58

[0115] As shown in Table 1, the 7-day unconfined compressive strength of the silt-stabilized soil prepared using the gelling agents obtained in Examples 1-3 as raw materials is 2.12-2.27 MPa, and the 28-day unconfined compressive strength is 3.57-3.81 MPa. This demonstrates that the low-carbon composite gelling agent prepared in this invention can effectively enhance the mechanical properties of the silt-stabilized soil.

[0116] (II) Using the gelling agents prepared in Examples 1-3 and Comparative Examples 1-2 as raw materials, solidified silt soil was prepared. After curing for 28 days, the solidified silt soil was subjected to freeze-thaw cycle resistance tests according to the test methods provided in GB / T 50082-2024. Under the condition of 25 freeze-thaw cycles, the mass loss rate and the unconfined compressive strength loss rate were detected. The specific test results are shown in Table 2.

[0117] Table 2

[0118] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Quality loss rate (%) 1.94 1.82 1.85 5.58 3.57 Unconfined compressive strength loss rate (%) 10.4 8.7 9.2 25.5 21.7

[0119] As shown in Table 2, the silt-stabilized soil prepared using the gelling agents obtained in Examples 1-3 as raw materials exhibited a mass loss rate of 1.82-1.94% and an unconfined compressive strength loss rate of 8.7-10.4% after 25 freeze-thaw cycles. This demonstrates that the low-carbon composite gelling agent prepared in this invention can effectively enhance the freeze-thaw cycle resistance of silt-stabilized soil.

[0120] (III) Using the gelling and curing agents prepared in Examples 1-3 and Comparative Examples 1-2 as raw materials, solidified silt soil was prepared. After a curing period of 28 days, the water stability performance of the prepared solidified silt soil was tested. The loss rate of unconfined compressive strength was detected after the sample was immersed in water for 24 hours. The specific test results are shown in Table 3.

[0121] Table 3

[0122] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Unconfined compressive strength loss rate (%) 3.8 2.5 2.7 15.3 12.8

[0123] As shown in Table 3, the silt-stabilized soil prepared using the gelling and curing agents obtained in Examples 1-3 as raw materials exhibited an unconfined compressive strength loss rate of 2.5-3.8% after 24 hours of soaking. This demonstrates that the low-carbon composite gelling and curing agent prepared in this invention can effectively enhance the water stability of silt-stabilized soil.

[0124] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A low-carbon composite cementitious curing agent for solidifying silt and soft soil, characterized in that: The raw materials for the low-carbon composite gelling agent are: activated steel slag, blast furnace slag, alkali activator, fiber reinforcing component, desulfurization ash, desulfurization gypsum, cement, and styrene-butadiene latex solution. The raw material composition of the low-carbon composite gelling agent is as follows by weight: 20-30 parts activated steel slag, 25-35 parts slag, 6-8 parts alkali activator, 1.5-2 parts fiber reinforcement component, 10-15 parts desulfurization ash, 6-8 parts desulfurization gypsum, 3-6 parts cement, and 3-5 parts styrene-butadiene latex solution. The activated steel slag is obtained by hot curing, rod milling, magnetic separation and grinding of liquid converter steel slag in the steel production process. The alkaline activator is obtained by mixing sodium carbonate, calcium hydroxide, and nano-alumina. The fiber reinforcement component preparation steps include pretreatment of hemp fiber and bamboo fiber, pretreatment of basalt fiber, and preparation of fiber reinforcement component. The pretreatment of hemp fiber and bamboo fiber involves soaking hemp fiber and bamboo fiber in NaOH solution and silane diluent, respectively, and then washing and drying them to obtain pretreated hemp fiber and pretreated bamboo fiber. The basalt fiber pretreatment involves immersing the basalt fiber in a silane solution and ultrasonically treating it for 30-40 minutes. After ultrasonic treatment, the fiber is removed, drained, and then coated with cement slurry. After drying, pretreated basalt fibers are obtained; The fiber reinforcement component is prepared by adding pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber to a high-speed mixer and stirring for 2-3 minutes to obtain the fiber reinforcement component; the mass ratio of the pretreated hemp fiber, pretreated bamboo fiber, and pretreated basalt fiber is (4-5):(2-3):(2-3).

2. The low-carbon composite cementitious curing agent for solidifying silt and soft soil according to claim 1, characterized in that: The mass ratio of sodium carbonate, calcium hydroxide, and nano-alumina is (4-6):(2-3):

1.

3. The method for preparing a low-carbon composite cementitious solidifying agent for solidifying silt and soft soil according to any one of claims 1-2, characterized in that: The steps include preparing fiber-reinforcing components, pretreating steel slag, and obtaining a low-carbon composite gelling agent. The preparation of the fiber reinforcement component includes the steps of pretreatment of hemp fiber and bamboo fiber, pretreatment of basalt fiber, and preparation of fiber reinforcement component. The pretreatment of hemp fiber and bamboo fiber involves soaking hemp fiber and bamboo fiber in NaOH solution and silane diluent, respectively, and then washing and drying them to obtain pretreated hemp fiber and pretreated bamboo fiber.

4. The preparation method of the low-carbon composite cementitious solidifying agent for solidifying silt and soft soil according to claim 3, characterized in that: The NaOH solution soaking: The NaOH solution used is a NaOH aqueous solution with a mass fraction of 5-10%, and the soaking time is 4-5 hours; The silane diluent soaking: The silane diluent used is a silane coupling agent ethanol solution with a mass fraction of 0.5-1%, and the silane coupling agent selected is KH-550, and the soaking time is 1-2 hours.

5. The preparation method of the low-carbon composite cementitious solidifying agent for solidifying silt and soft soil according to claim 3, characterized in that: The amount of cement paste used is 5-10% of the mass of basalt fiber; the silane solution is an aqueous solution of silane coupling agent with a mass fraction of 1-1.2%, and the silane coupling agent is KH-570; the water-cement ratio of the cement paste is 0.5-0.6, and the cement is ordinary Portland cement P.O42.

5.

6. The preparation method of the low-carbon composite cementitious solidifying agent for solidifying silt and soft soil according to claim 3, characterized in that: The steel slag pretreatment involves simmering the steel slag in hot water at 70-80°C for 5-6 hours. After simmering, the steel slag is crushed using a rod mill for 30-40 minutes. After crushing, magnetic separation is performed for 30-40 minutes to remove impurities. Then, the slag is ground for 30-40 minutes to obtain activated steel slag.

7. The preparation method of the low-carbon composite cementitious solidifying agent for solidifying silt and soft soil according to claim 3, characterized in that: The low-carbon composite gelling agent is prepared by adding activated steel slag, blast furnace slag and alkali activator into a twin-shaft mixer and stirring for 10-15 minutes. Add the fiber-reinforcing component and continue stirring for 10-15 minutes; add the desulfurized gypsum and desulfurized ash, increase the speed to 400-500 rpm, and stir for 10-20 minutes. Add styrene-butadiene latex solution, increase the rotation speed to 500-600 rpm, and stir for 8-10 minutes to obtain a mixture; spread cement evenly on the surface of the mixture and stir for 6-10 minutes to obtain a low-carbon composite gelling agent; the styrene-butadiene latex solution is obtained by mixing styrene-butadiene latex and deionized water at a mass ratio of 1:1.