A new type of solidification material and solidification method for soft soil

Abstract

The invention discloses a novel solidifying material and a solidifying method for soft soil. The novel solidifying material comprises the following raw materials in parts by weight: 70-80 parts of solid waste admixture, 4-10 parts of cement clinker, 15-20 parts of waste desulfurized gypsum, 3-8 parts of amphoteric straw cellulose, 4-10 parts of rice husk ash-based water glass, 0.5-3 parts of sodium sulfate, and 1-4 parts of lignin sulfonate calcium salt. The solid waste admixture is a mixture of tailings slag powder, steel slag powder, fly ash, silica ash, and bagasse ash in a mass ratio of (3-5):(0.5-2):(4-6):(1-2.5):(3-5), and the generation rates of cementitious hydrates and expansive hydrates in the solidification process are coordinated by adjusting the doping ratio of waste slags with different activities. The new type of solidifying material of the present invention is added to the soft soil to be solidified, which gives the new type of solidifying material of the soft soil a higher solidification effect and technical advantages, and has potential application prospects; in addition, the present invention recycles industrial solid waste and agricultural waste, which helps to ease resource constraints, reduce environmental pollution, and conform to the green and low-carbon environmental protection orientation.

Description

Technical Field

[0001] The invention relates to the field of civil engineering and building materials, and in particular to a new type of soft soil solidifying material and a solidifying method. Background Art

[0002] Soft soil is a type of clay soil in a soft plastic to fluid plastic state formed through slow sedimentation and a series of biological and chemical reactions. It is a general term for a type of soil, not a specific type of soil. In engineering, soft soil is often subdivided into soft clay soil, silt soil, silt, tidal flat, swamp, peat soil and peat, etc. Due to the characteristics of soft soil such as high water content, high porosity, high compressibility, low shear strength, small consolidation coefficient, long consolidation time, high disturbance, low bearing capacity, and complex layered distribution of soil layers, it needs to be solidified in advance before the infrastructure process.

[0003] The solidification treatment of soft soil is to strengthen the soft soil by means of replacement, compaction, compaction, drainage, bonding, reinforcement and thermal methods, improve its engineering properties, increase shear strength, reduce compressibility and uneven settlement, improve the permeability of the foundation, and improve the unfavorable geological properties of special soils, and finally improve the stability and bearing capacity of the foundation and ensure the structural safety of the building. Among the many solidification treatment methods, the use of soft soil solidifier is a fast and effective means. After the soft soil solidifier is fully mixed with the soft soil, the physical and chemical reactions between its own components and between it and the soil can significantly improve the physical and mechanical properties of the soil, and can form a solidified body that meets the design requirements and maintains long-term stability.

[0004] Various chemical factors in soft soil, such as the pH value of soil samples, ion exchange, physical adsorption, and hardening reaction, affect the hydration and hardening process of the curing agent. Soft soil curing requires a unique hydration system, and the curing material should provide cementitious hydrates, expansive hydrates, and sufficient alkalinity. At present, although traditional calcium-based curing agents such as cement and lime can produce cementitious hydrates and convert loose soil into dense cementitious materials; but the lack of expansive hydrates cannot effectively squeeze and fill the pores in the soil aggregates, causing problems such as large soil shrinkage, easy cracking, and poor water stability; the lack of sufficient alkaline components cannot ensure that the cured soil is in an alkaline environment suitable for the formation of hydrates, the curing time is long, and the reinforcement efficiency is low. In addition, cement has a poor curing effect on clay, organic soil, and saline soil with a high plasticity index, and sometimes even has no curing effect, resulting in low strength and poor water stability of the cured soil. Summary of the invention

[0005] In view of the above technical status, the present invention provides a new type of solidifying material and solidifying method for soft soil, which solves the problems of low strength, environmental pollution and uneconomical of existing solidifying agents.

[0006] In a first aspect, the present invention provides a new type of solidification material for soft soil.

[0007] A new type of solidifying material for soft soil, comprising the following raw materials in parts by weight:

[0008] 70~80 parts of solid waste admixture, 4~10 parts of cement clinker, 15~20 parts of waste desulfurized gypsum, 3~8 parts of amphoteric straw cellulose, 4~10 parts of rice husk ash-based water glass, 0.5~3 parts of sodium sulfate; 1~4 parts of lignin sulfonate calcium salt;

[0009] The solid waste admixture is a mixture of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in a mass ratio of (3-5):(0.5-2):(4-6):(1-2.5):(3-5);

[0010] The amphoteric straw cellulose is straw cellulose modified by silane and sulfonate, and the preparation method thereof comprises the following steps:

[0011] S1. Straw pretreatment: remove the leaves from the straw, cut the straw into sections, wash them, sterilize them in boiling water for 1 hour, dry them in an oven, crush them with a pulverizer, grind them mechanically, and then pass them through a 60-mesh sieve to obtain straw powder;

[0012] S2. Purification of straw cellulose: reflux degreasing of straw powder in toluene-ethanol solution in turn; cooling and filtering, boiling and heating the filter residue in nitric acid-ethanol solution to remove lignin and hemicellulose; filtering, washing and freeze-drying the obtained solid product to obtain straw cellulose powder;

[0013] The purpose of defatting is to remove wax and other lipids on the surface, making the straw powder rough, enlarging the internal pores, and increasing the specific surface area of ​​the powder material; ethanol and nitric acid can remove lignin and dissolve hemicellulose respectively; freeze-drying helps to form smaller and more uniform particles.

[0014] S3, preparation of silanized straw cellulose: under the conditions of nitrogen atmosphere, organic solvent 1 and triethylamine, reflux reaction is carried out for a period of time with straw cellulose and chloromethylphenethyl tri(trimethylsiloxy)silane (CAS No.: 167426-89-3) in a mass ratio of 1:(3~4); after the reaction, the crude product is obtained by rotary evaporation, which is redissolved in organic solvent 1, extracted with distilled water, and the organic phase is collected and dried with anhydrous magnesium sulfate overnight; the solid is obtained by rotary evaporation again, which is recrystallized with ethanol and dried in an oven at 60°C for 24 hours to obtain silanized straw cellulose;

[0015] S4. Preparation of amphoteric straw cellulose: Silylated straw cellulose and 2-methyl-2-acrylic acid-2-sulfoethyl ester (CAS No.: 10595-80-9) in a mass ratio of (1.5-2):1 are mixed and reacted in an organic solvent II under a nitrogen atmosphere and an initiator; after the reaction, the crude product is subjected to Soxhlet extraction with acetone for 72 hours, and vacuum dried at 60°C for 24 hours to obtain amphoteric straw cellulose.

[0016] Furthermore, the straw in S1 is selected from one of wheat straw, corn straw, sesame straw, rice straw, sweet potato straw and sorghum straw; and the drying temperature is 60-80°C.

[0017] S2 The volume ratio of toluene to ethanol in the toluene-ethanol solution is (2~3):1, and the degreasing reflux temperature is 70~80°C; the solid-liquid ratio of the nitric acid-ethanol solution is 1:(20~25) g / mL, the boiling temperature is 100°C, and the boiling time is 2~3h until the solution turns white; the freeze-drying conditions are cooling at -18~-20°C and then freeze-drying at -80°C for 8~12h.

[0018] Furthermore, the organic solvent in S3 is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetone, acetonitrile, 1,4-dioxane and 1,2-dichloroethane; and the reaction conditions are nitrogen atmosphere, reflux at 40-50°C for 6-10h.

[0019] Further, the organic solvent 2 in S4 is one of a paraformaldehyde-dimethyl sulfoxide system, a nitrogen tetroxide-dimethylformamide system, a lithium chloride-dimethylacetamide system, and a sodium hydroxide-urea system;

[0020] The initiator is used in an amount of 0.05wt% to 0.12wt%, and is selected from at least one of potassium persulfate (KPS), ammonium persulfate (APS), cerium ammonium nitrate, dicumyl peroxide (DCP), benzoyl peroxide (BPO), N,N'-methylenebisacrylamide (MBA), and sodium bisulfite;

[0021] The reaction conditions are as follows: the silanized straw cellulose is first contacted with the initiator for 5-10 minutes, and then 2-methyl-2-acrylic acid-2-sulfoethyl ester is added and the temperature is raised to 40-60° C. for graft polymerization for 20-24 hours.

[0022] Furthermore, the cement clinker is ordinary Portland cement with a strength grade of 42.5 or above; that is, the cement grade can be any one of 42.5, 42.5R, 52.5, and 52.5R.

[0023] The waste desulfurization gypsum is the desulfurization gypsum dried at 40-60°C in a power plant and needs to be ground to a specific surface area of ​​400m 2 / kg;

[0024] Industrial waste desulfurization gypsum is solid waste discharged from the manufacture of chemical reagents such as phosphoric acid and hydrofluoric acid. Its main component is calcium sulfate, which can be hydrated to produce dihydrate gypsum to form a skeleton and generate strength; it can also generate calcium aluminate with fly ash and have a volcanic ash-stimulating effect on fly ash.

[0025] The tailings slag powder is granulated blast furnace active slag powder of S95 grade or above, with a 28d activity index of ≥95%, and needs to be ground to a specific surface area of ​​>400m 2 / kg;

[0026] Slag powder can be divided into three grades according to different activity indexes: S75, S95 and S105. The larger the number, the higher the grade and the better the activity. When used as a cementitious material, the strength is better; adding slag powder can also improve the soil pore structure, improve chlorine resistance and durability.

[0027] The steel slag powder is selected from the first-grade steel slag powder or the second-grade steel slag powder of steelmaking, and its 28d activity index is ≥65%, and it needs to be ground to a specific surface area of ​​>300m 2 / kg;

[0028] Steel slag is a solid solution discharged in large quantities during steelmaking, the main mineral components of which include tricalcium silicate, dicalcium silicate, calcium forsterite, calcium aluminoferrite, and oxides of silicon, magnesium, iron, manganese, and phosphorus. After grinding, its volcanic ash activity increases.

[0029] The fly ash is selected from Class I or Class II fly ash collected after the incineration process, and its 28d activity index is ≥70%;

[0030] Fly ash is a solid residue produced when burning coal. Its main components are silicon oxide and aluminum oxide. It has high cementing activity and has volcanic ash effect and micro-aggregate effect.

[0031] The silica ash is a fine granular powder produced in the process of silicon smelting or silicon alloying, and the silicon dioxide content is ≥93%;

[0032] Silica ash has a large specific surface area and produces a strong volcanic ash reaction in the solidified soil, effectively improving the strength of the solidified soil; the extremely fine particles of silica ash can play a filling role and increase the density of the solidified soil.

[0033] The bagasse ash is fine ash obtained by calcining bagasse at 800° C., pickling with hydrochloric acid, crushing with a crusher, drying, and grinding through a 200-mesh sieve.

[0034] Slag, steel slag powder, fly ash, silica fume, and bagasse ash are all volcanic ash materials, containing Si-Al-Na(K)-Ca glass. On the one hand, they can undergo hydration reaction to form hydraulic calcium silicate hydrate and calcium aluminate hydrate, improving the interfacial adhesion of soft soil; on the other hand, they will also react with calcium hydroxide in cement and sulfate ions in sodium sulfate to form expansive hydrates such as calcium aluminate, improving the curing strength and compressive resistance of soft soil. There are differences in the activity of different types of powders: silica fume has the strongest volcanic ash effect, mainly contributing to improving early strength; bagasse ash and fly ash are second; and steel slag powder produces cementitious hydration products at the slowest rate. The addition of multiple components produces a superposition effect, ensuring the coordination of the growth process of expansive hydrates and cementitious hydrates, which not only avoids excessive reaction and the destruction of the solidified soil structure formed by early cementitious hydrates by expansive hydrates; but also prevents insufficient activity from reducing the curing efficiency.

[0035] Furthermore, the rice husk ash-based water glass is obtained by the following steps: removing impurities from crude rice husk ash, crushing, pickling with 1 mol / L hydrochloric acid, washing with water for multiple times, centrifugal drying, and grinding through a 100-mesh sieve to obtain rice husk ash; adding the rice husk ash to a caustic soda solution, stirring and boiling, filtering, washing the filter residue with boiling water, collecting the supernatant and the filter residue washing liquid, and concentrating them with a rotary evaporator to obtain the rice husk ash-based water glass.

[0036] Rice husk ash is a waste residue produced by burning or gasifying rice husk as fuel. Its main chemical composition is SiO2 with a mass fraction of more than 80%. 2 , a small amount of C and trace amounts of K, Na, Ca, Al, etc. Acid washing and water washing are performed to remove water-soluble metal salts, acid ions, phosphorus compounds and other water-soluble impurities to avoid heavy metal pollution of soft soil.

[0037] Furthermore, the liquid ratio of the rice husk ash to the caustic soda solution is 1:5, and the concentration of the caustic soda is 10wt%; the dissolution conditions are a pressure of 0.6MPa, a dissolution temperature of 100°C, a stirring speed of 300rpm, and a dissolution time of 6h.

[0038] Furthermore, the modulus of the rice husk ash-based water glass is 2.2-2.5, and the silicon dioxide dissolution rate is greater than 90%.

[0039] Sodium sulfate and rice husk ash-based water glass act as alkaline activators. After hydrolysis, they provide OH-, which can break the Si-O-Si and Al-O-Al bonds in the silicon-rich phase of the material, thereby dissolving the glass components such as silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron in the admixture to form liquid [SiO] 4- and [AlO] 4- , accelerating and Ca in the system 2+ and Al 3+ The polycondensation reaction helps to improve the strength of soft soil.

[0040] In a second aspect, the present invention provides a method for curing a new type of curing material for soft soil, namely, adding the above-mentioned new curing material into the soft soil to be cured; wherein the amount of the new curing material added is 6% to 15% of the mass of the soft soil.

[0041] The present invention has the following beneficial effects:

[0042] The present invention provides a new type of soft soil solidification material and a solidification method thereof according to the particularity of the hydrate composition required for soft soil solidification and the characteristics of the solidified soil structure formation process. By selectively selecting waste residues with different activities for doping and adjusting the coordination of the generation rates of cementitious hydrates and expansive hydrates during the solidification process, the new type of soft soil solidification material is endowed with a higher solidification effect and technical advantages; the solidification material can be directly mixed with soft soil particles at room temperature; compared with ordinary cement, the strength of soft soil can be increased several times.

[0043] The present invention modifies the purified straw cellulose to obtain amphoteric straw cellulose containing silicon methyl hydrophobic groups and sulfonic acid hydrophilic groups, thereby reducing surface tension and improving reinforcement efficiency; Si-OCH 3 The hydrophobic part is easily hydrolyzed into Si-OH, which produces hydrogen bonds with the -OH in the solid particles, effectively strengthening the soil; the hydrophilic sulfonic acid group improves the wettability and lubricity between the particles, reduces the water seepage rate of soft soil; it also promotes contact and bonding between the solid phase and the water phase, and improves soil strength.

[0044] The present invention applies industrial waste tailings, steel slag, fly ash, silica fume and agricultural waste bagasse ash to the preparation of soft soil solidification materials, which solves the problem of improper disposal and waste of solid waste; at the same time, the solid waste admixture replaces part of the cement dosage, reduces the construction project cost, is more economical, environmentally friendly, and low-carbon, and meets the green building and production goals.

[0045] The present invention uses agricultural waste rice husk ash and straw for water glass preparation and cellulose extraction, effectively improving their utilization value and economic value, and realizing high-value recycling and utilization transformation of agricultural resources; it helps to ease resource constraints, reduce environmental pollution, and conform to the green and low-carbon environmental protection orientation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a preparation route for amphoteric straw cellulose.

[0047] Figure 2 These are the infrared spectra of straw cellulose, silanized straw cellulose and amphoteric straw cellulose. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. Unless otherwise specified, the compounds used in the present invention and related reagents can be purchased from the market.

[0049] The soft soil samples used in the following examples were taken from untreated river dredging sludge in Guangzhou, with a water content of 73% and in a plastic state.

[0050] The invention provides a novel solidifying material for soft soil, comprising the following components in parts by weight: 70-80 parts of solid waste admixture, 4-10 parts of cement clinker, 15-20 parts of waste desulfurized gypsum, 3-8 parts of amphoteric straw cellulose, 4-10 parts of rice husk ash-based water glass, 0.5-3 parts of sodium sulfate, and 1-4 parts of lignin sulfonate calcium salt.

[0051] In some embodiments of the present invention, the solid waste admixture is a mixture of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in a mass ratio of (3~5):(0.5~2):(4~6):(1~2.5):(3~5).

[0052] In some embodiments of the present invention, the cement clinker used is 42.5 silicate cement with a specific surface area of ​​350m 2 / kg, density 3.10g / cm 3 , initial setting time 130min, final setting time 190min, loss on ignition 1.87%, 28d compressive strength 53.2MPa, 28d flexural strength 9MPa.

[0053] In some embodiments of the present invention, the waste desulfurization gypsum used is construction waste desulfurization gypsum, with an initial setting time of 6 minutes, a final setting time of 12 minutes, a compressive strength of 10 MPa, and a loss on ignition of 6.05%.

[0054] In some embodiments of the present invention, the tailings slag powder used is S95 grade granulated blast furnace active slag powder, and its density is 2.90g / cm 3 , specific surface area is 450m 2 / kg, the 7-day activity index was 81%, and the 28-day activity index was 103%.

[0055] In some embodiments of the present invention, the steel slag powder used is the secondary steel slag powder obtained by grinding the iron smelting waste slag of Anyang Jin, with a specific surface area of ​​400m 2 / kg, density 0.4g / cm 3 、Average particle size 68 μ m, 28d activity index 83%, loss on ignition 0.58%.

[0056] In some embodiments of the present invention, the fly ash used is Class II fly ash collected from the flue gas after coal combustion, with a specific surface area of ​​452 m 2 / kg, density 2.05g / cm 3 , 7d activity index is 64%, 28d activity index is 75%, and loss on ignition is 6.15%.

[0057] In some embodiments of the present invention, the silicon ash used is a fine granular powder produced by silicon smelting or silicon alloying process, with a silicon dioxide content of 94.7% and a specific surface area of ​​20 m 2 / g, loss on ignition 1.9%.

[0058] In some embodiments of the present invention, the bagasse ash used is the fine ash obtained by calcining, crushing, grinding, pickling, drying, and grinding the bagasse raw materials, which are the waste materials of a sugar factory provided by Guangxi Senbaiyuan Agriculture Co., Ltd., through a 200-mesh sieve at 800°C, with a sieve residue of 7.54%.

[0059] The chemical compositions of cement, waste desulfurized gypsum and various solid waste admixtures were determined by Philips PW1400X-fluorescence spectrometry. The results are shown in Table 1.

[0060] Table 1

[0061]

[0062] In some embodiments of the present invention, the steps of preparing the amphoteric straw cellulose are as follows:

[0063] S1. Straw pretreatment: remove the leaves of wheat straw (purchased from Zhengyang County Xintiandi Grass Industry Co., Ltd.), cut into segments, wash, sterilize with boiling water for 1 hour, dry in a 60°C oven, crush with a pulverizer, grind mechanically, and pass through a 60-mesh sieve to obtain straw powder.

[0064] S2. Purification of straw cellulose: The straw powder was dissolved in a toluene / ethanol solution with a volume ratio of 2:1, and degreased by high-temperature reflux at 70°C; the mixture was cooled and filtered, and the filter residue was added to a nitric acid-ethanol solution, and heated in a boiling water bath for 3 hours until the mixture solution turned white; the mixture was cooled and filtered again, and the filter residue was washed with hot water until neutral, and then washed three times with anhydrous ethanol and deionized water in sequence; the mixture was frozen at -20°C for 24 hours and then freeze-dried at -80°C for 12 hours to obtain straw cellulose powder. The cellulose yield was measured to be 70.15% and the purity was 68.57%.

[0065] The chemical components of straw mainly include cellulose, hemicellulose and lignin. Cellulose is a sugar unit polymer composed of glucose; hemicellulose is a non-crystalline polymer, the main component of which is a variety of polysaccharide units, which is more soluble in water and hydrolyzed; lignin is a non-crystalline mixture of aromatic polymers and phenylpropane monomers, with poor thermal stability, insoluble in water but soluble in organic solutions. Ethanol solvent and nitric acid can remove lignin, dissolve and remove hemicellulose, and reduce the crystallinity of cellulose.

[0066] S3. Preparation of silanized straw cellulose: Under a nitrogen atmosphere, 20 mL DMSO solution containing 1.420 g of straw cellulose and 20 mL DMSO solution containing 4.493 g of chloromethylphenethyltri(trimethylsiloxy)silane were mixed evenly in an ice bath at 0°C. After adding triethylamine, the reaction system was kept at 0°C for 6 h. After the reaction was completed, the filtrate was repeatedly washed with 5% sodium hydroxide solution and deionized water until neutral, the solvent was evaporated, and the silanized straw cellulose was obtained by concentration and crystallization with a yield of 82.3%.

[0067] It should be noted that in the above reaction, the structural unit of the cellulose macromolecule contains three free hydroxyl groups: one primary hydroxyl group on the 6-carbon atom and two secondary hydroxyl groups on the 2.3-carbon atom. There is a methoxy group in the adjacent structural unit of the 2-carbon atom, and there are two free hydroxyl groups on the 3- and 6-positions of the glucose ring in the structural unit. Generally, the primary hydroxyl group on the 6-carbon atom has less steric hindrance, so its reactivity and degree of substitution are greater than those of the secondary hydroxyl group on the 3-carbon atom.

[0068] S4. Synthesis of amphoteric straw cellulose: 2.77 g of silanized straw cellulose was added to 50 mL of anhydrous polyformaldehyde-dimethyl sulfoxide solution with a molar ratio of 1:1 under a nitrogen atmosphere, and 0.54 g of KPS was added after heating to 60°C, and the mixture was stirred for 5-10 min; then 4.00 g of 2-methyl-2-acrylic acid-2-sulfoethyl ester was added in batches, and the reaction was continued at 60°C and nitrogen atmosphere for 24 h to obtain a crude product of an emulsion aqueous dispersion; the crude product was subjected to Soxhlet extraction with acetone for 72 h, and vacuum dried at 60°C to obtain the product; the grafting rate was 58.45%.

[0069] After silanization modification of straw cellulose, there are two secondary hydroxyl groups on the 2nd and 3rd carbon atoms in its molecular structure unit, both of which may react with the anion free radical SO generated by the decomposition of KPS. 4 -Reaction: SO 4- Seize the hydrogen atoms in the hydroxyl group, generate macromolecular free radicals in the cellulose substrate, and then initiate the graft copolymerization reaction. Therefore, in the process of graft polymerization, the above two ways of generating macromolecular free radicals exist at the same time, but the positions and ways of their action are different, but their common role is to initiate the continuous grafting of monomer molecules to the active points of macromolecular free radicals in the substrate.

[0070] The process of modifying straw cellulose to obtain amphoteric straw cellulose is shown in Figure 1 The infrared spectra of straw cellulose, silanized straw cellulose and amphoteric straw cellulose are shown in Figure 2 .

[0071] Depend on Figure 2 , 797 cm -1 It is the antisymmetric vibration of Si-O-Si bond; 1050cm -1 The absorption peak nearby becomes stronger, which is the superposition of the stretching vibration absorption peak of the Si-O bond and the ether bond of cellulose, both indicating that siloxane is successfully grafted onto the cellulose molecular chain.

[0072] The amphoteric straw cellulose is between 1000 and 1100 cm -1 The strongest absorption peak is due to the absorption of the SO bond; the stretching vibration of the S=O bond appears, 1308cm -1 There is also a sulfonic acid group (-SO 3 The characteristic absorption peak of H- is 1160 cm -1 The nearby ester (CC(=O)-O) bond and carbonyl (C=O) are at 1745 cm -1 There is absorption at , indicating that 2-methyl-2-acrylic acid-2-sulfoethyl ester is grafted onto the cellulose molecular chain.

[0073] In some embodiments of the present invention, the rice husk ash-based water glass preparation steps are as follows:

[0074] The crude rice husk ash was removed from the impurities, crushed by a pulverizer, pickled with 1mol / L hydrochloric acid, washed with water for multiple times, centrifugally dried, mechanically ground and passed through a 100-mesh sieve to obtain rice husk ash; rice husk ash was added to a 10wt% caustic soda aqueous solution to obtain a rice husk ash-caustic soda solution with a solid-liquid ratio of 1:5; and dissolved and boiled for 6 hours at 100°C, 0.6MPa pressure and 300rpm stirring; after the reaction was completed, the filter was filtered, the filter residue was washed with boiling water, the supernatant and the filter residue washing liquid were collected and concentrated by a rotary evaporator to obtain rice husk ash-based water glass. The silicon dioxide dissolution rate in rice husk ash was determined to be 93.5% using GB / T4209-2022 "Determination Method for Industrial Sodium Silicate" and the modulus of rice husk ash-based water glass was 2.34.

[0075] Example 1

[0076] A new type of solidifying material for soft soil, comprising, by weight: 10 parts of cement clinker, 70 parts of solid waste admixtures, 20 parts of waste desulfurized gypsum, 4 parts of amphoteric straw cellulose, 8 parts of rice husk ash-based water glass, 3 parts of sodium sulfate; 2 parts of lignin sulfonate calcium salt; the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 3:1:5:2:3.

[0077] The raw materials are weighed according to the distribution ratio of each group, put into a mixer and mixed evenly to obtain a new soft soil solidification material.

[0078] Example 2

[0079] A new type of solidifying material for soft soil, comprising, by weight: 7 parts of cement clinker, 75 parts of solid waste admixtures, 18 parts of waste desulfurized gypsum, 5 parts of amphoteric straw cellulose, 9 parts of rice husk ash-based water glass, 2 parts of sodium sulfate; 3 parts of lignin sulfonate calcium salt; the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 3:1:5:2:3.

[0080] The raw materials are weighed according to the distribution ratio of each group, put into a mixer and mixed evenly to obtain a new soft soil solidification material.

[0081] Example 3

[0082] A new type of solidifying material for soft soil, comprising, by weight: 5 parts of cement clinker, 80 parts of solid waste admixtures, 15 parts of waste desulfurized gypsum, 7 parts of amphoteric straw cellulose, 10 parts of rice husk ash-based water glass, 1 part of sodium sulfate; 1 part of lignin sulfonate calcium salt; the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 3.5:1:5:4.5:2:3.5.

[0083] The raw materials are weighed according to the distribution ratio of each group, put into a mixer and mixed evenly to obtain a new soft soil solidification material.

[0084] Example 4

[0085] Compared with Example 2, the difference between this embodiment and Example 2 is that the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 5:2:4:1:3.

[0086] Example 5

[0087] Compared with Example 2, the difference between this embodiment and Example 2 is that the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 4.5:0.5:5.5:2.5:5.

[0088] Example 6

[0089] Compared with Example 2, the difference between this embodiment and Example 2 is that the mass ratio of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in the solid waste admixture is 3:1:6:1.5:4.

[0090] Application Examples 1~6

[0091] 120 kg of the soft soil solidification material products obtained in Examples 1 to 6 were added to each cubic meter of silt soft soil; a certain amount of water was added to control the water-cement ratio to 0.5, and after uniform mixing, 50 mm × 50 mm × 50 mm test pieces were prepared and vibrated into shape according to JTGE30 highway engineering cement and cement concrete test procedures; the molds were removed after 2 days, and the samples were placed in a curing box for curing at a temperature of (25 ± 2) ° C and a humidity of (95 ± 2)%.

[0092] Application Examples 7~8

[0093] In each cubic meter of silt soft soil, 60 kg and 150 kg of the soft soil solidification material obtained in Example 1 were added respectively. Other operations were the same as those in Application Example 2.

[0094] Comparative application example 1

[0095] The soft soil solidifying agent produced by a chemical production company in Wuxi was used as the soft soil solidifying material, and its usage amount was the same as that in Application Example 2.

[0096] Three sets of parallel samples were used to measure the unconfined compressive strength of the solidified soil at the curing age of 7d, 14d and 28d. Table 2 shows the test results of application examples 1 to 8 and comparative application example 1.

[0097] Table 2

[0098]

[0099] As can be seen from Table 2, the unconfined compressive strength of the soft soil solidifying agent prepared by the technical solution of the present invention is significantly improved. Application Example 2 and Application Examples 4 to 6 are optimization comparisons of the dosage of different solid waste admixtures. The proportion of silica fume in Application Example 5 is the largest, and the strength growth at 7d is the fastest; steel slag is the weakest, and in Application Example 4 with the largest content of steel slag, the early strength lags behind, but the later strength increases rapidly. Within the scope of the present invention, the mixing of five kinds of volcanic ash powders all achieves a more ideal solidification effect for the silt soft soil. The amount of soft soil solidifying agent in Application Examples 7, Application Examples 2 and Application Examples 8 gradually increases, and the unconfined compressive strength of the solidified soft soil at different ages is also gradually enhanced.

[0100] The above embodiments are merely examples of the technical solutions of the present invention. The new type of solidifying material and solidifying method for soft soil involved in the present invention are not limited to those described in the above embodiments, but are subject to the scope defined in the claims. Any modification, supplement or equivalent replacement made by a person skilled in the art based on the embodiment is within the scope of protection claimed by the present invention.

Claims

1. A new type of solidifying material for soft soil, characterized in that: The invention comprises the following raw materials in parts by weight: 70~80 parts of solid waste admixture, 4~10 parts of cement clinker, 15~20 parts of waste desulfurized gypsum, 3~8 parts of amphoteric straw cellulose, 4~10 parts of rice husk ash-based water glass, 0.5~3 parts of sodium sulfate; 1~4 parts of lignin sulfonate calcium salt; The solid waste admixture is a mixture of tailings slag powder, steel slag powder, fly ash, silica ash and bagasse ash in a mass ratio of (3-5):(0.5-2):(4-6):(1-2.5):(3-5); the tailings slag powder is granulated blast furnace active slag powder above S95 grade, with a 28d activity index of ≥95%, and needs to be ground to a specific surface area of ​​>400m 2 / kg; the waste desulfurization gypsum is waste desulfurization gypsum for construction, with an initial setting time of 6 minutes, a final setting time of 12 minutes, a compressive strength of 10 MPa, and a loss on ignition of 6.05%; The amphoteric straw cellulose is straw cellulose modified by silane and sulfonate, and the preparation method thereof comprises the following steps: S1. Straw pretreatment: remove the leaves from the straw, cut the straw into segments, wash them, boil them for sterilization, dry them, crush them, grind them mechanically, and then sieve them to obtain straw powder; S2. Purification of straw cellulose: The straw powder is sequentially subjected to reflux degreasing in a toluene-ethanol solution, and then dissolved and heated in a nitric acid-ethanol solution to remove lignin and hemicellulose; the obtained solid product is freeze-dried to obtain straw cellulose powder; S3, preparation of silanized straw cellulose: under nitrogen atmosphere, organic solvent 1 and triethylamine, straw cellulose powder and chloromethylphenethyl tris(trimethylsiloxy)silane in a mass ratio of 1:(3-4) were refluxed to obtain silanized straw cellulose; S4. Synthesis of amphoteric straw cellulose: Silylated straw cellulose and 2-methyl-2-acrylic acid-2-sulfoethyl ester in a mass ratio of (1.5-2):1 are mixed and reacted in an organic solvent in a nitrogen atmosphere and an initiator to obtain amphoteric straw cellulose.

2. The novel curing material according to claim 1, characterized in that: S1 The straw is selected from one of wheat straw, corn straw, sesame straw, rice straw, sweet potato straw and sorghum straw; the drying temperature is 60-80°C; The volume ratio of toluene to ethanol in the toluene-ethanol solution of S2 is (2-3):1, and the reflux degreasing temperature is 70-80°C; The solid-liquid ratio of the nitric acid-ethanol solution is 1:(20-25) g / mL, the boiling temperature is 100° C., and the boiling time is 2-3 hours until the solution turns white; The freeze-drying conditions are as follows: freezing at -18 to -20°C and then freeze-drying at -80°C for 8 to 12 hours.

3. The novel curing material according to claim 1, characterized in that: S3 The organic solvent 1 is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetone, acetonitrile, 1,4-dioxane and 1,2-dichloroethane; The reaction conditions are nitrogen atmosphere, reflux at 40-50° C. for 6-10 h.

4. The novel curing material according to claim 1, characterized in that: The second organic solvent in S4 is one of a paraformaldehyde-dimethyl sulfoxide system, a nitrogen tetroxide-dimethylformamide system, a lithium chloride-dimethylacetamide system, and a sodium hydroxide-urea system; The initiator is used in an amount of 0.05wt% to 0.12wt%, and is selected from at least one of potassium persulfate, ammonium persulfate, cerium ammonium nitrate, dicumyl peroxide, benzoyl peroxide, N,N'-methylenebisacrylamide, and sodium bisulfite; The reaction conditions are as follows: the silanized straw cellulose is first contacted with the initiator for 5-10 minutes, and then 2-methyl-2-acrylic acid-2-sulfoethyl ester is added and the temperature is raised to 40-60° C. for graft polymerization for 20-24 hours.

5. The novel curing material according to claim 1, characterized in that: The steel slag powder is selected from the first-grade steel slag powder or the second-grade steel slag powder of steelmaking, with a 28d activity index of ≥65%, and needs to be ground to a specific surface area of ​​>300m 2 / kg; The fly ash is selected from Class I or Class II fly ash collected after the incineration process, and the 28d activity index is ≥70%; The silica ash is a fine granular powder produced in the process of silicon smelting or silicon alloying, and the silicon dioxide content is ≥93%; The bagasse ash is fine ash obtained by calcining bagasse at 800° C., pickling with hydrochloric acid, crushing with a crusher, drying, and grinding through a 200-mesh sieve.

6. The novel curing material according to claim 1, characterized in that: The rice husk ash-based water glass is obtained by the following steps: removing impurities from crude rice husk ash, crushing, washing with hydrochloric acid, washing with water for multiple times, centrifugally drying and grinding, and then sieving to obtain rice husk ash; adding the rice husk ash into a caustic soda solution, stirring and boiling, and filtering the material; washing the filter residue with boiling water, collecting the supernatant and the filter residue washing liquid, and concentrating them to obtain the rice husk ash-based water glass.

7. The novel curing material according to claim 6, characterized in that: The dissolution conditions are as follows: a pressure of 0.6 MPa, a dissolution temperature of 100° C., a stirring speed of 300 rpm, and a dissolution time of 6 hours; the modulus of the rice husk ash-based water glass is 2.2-2.5, and the silicon dioxide dissolution rate is greater than 90%.

8. A method for curing a new type of curing material for soft soil, characterized in that: The novel solidifying material as claimed in any one of claims 1 to 7 is added into the soft soil to be solidified; wherein the amount of the novel solidifying material added is 6% to 15% of the mass of the soft soil.

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