Soft soil stabilizer and method of use

Abstract

The application discloses a soft soil solidifying agent and an application method thereof, and belongs to the technical field of soft soil solidification. The soft soil solidifying agent is composed of components with the following weight ratio: m(desulfurized gypsum):m(steel slag micro powder):m(slag powder):m(cement clinker):m(polypropylene fiber):m(magnesium oxide nano material):m(nano silicon)=(10-12):(40-43):(39-41):(4.5-5):(0.3-0.5):(0.3-0.33):(0.3-0.33). The application can effectively reduce the cement mixing amount, realize the recycling of solid waste resources, is favorable for reducing the solid waste emission, realizes energy saving and environmental protection, and can effectively improve the mechanical property and crack resistance of the solidified soil, so that the solidification effect of the solidifying agent is ensured.

Description

Technical Field

[0001] This invention belongs to the field of soft soil solidification technology, and more specifically, relates to a soft soil solidification agent and its application method. Background Technology

[0002] my country has a large area of ​​soft soil, characterized by high water content, high compressibility, low shear strength, and a small consolidation coefficient. Under external loads, it requires a relatively long period of compression and consolidation to stabilize, and it also experiences significant settlement and uneven deformation. Therefore, it is necessary to reinforce the soft soil before infrastructure construction to improve its bearing capacity. Mixing a solidifying agent with the soft soil to harden it into solidified soil with sufficient strength is the most widely used soft soil reinforcement technology.

[0003] Currently, cement is the primary solidifying agent used, but its effectiveness in solidifying soft soil is low, its cost is high, and its production has a significant environmental impact. Therefore, developing new solidifying agents is imperative. Meanwhile, my country's annual solid waste production exceeds 1 billion tons, with a cumulative stockpile exceeding 6.7 billion tons, occupying 654.12 million square meters of land, severely hindering sustainable development. There is an urgent need to develop high-value-added, resource-utilizing technologies for waste residue. Although there is considerable research on preparing soft soil solidifying agents using industrial waste residue, there are few reports of large-scale application or industrialization. The reason for this is that most solidifying agents are obtained through rather haphazard trial-and-error methods, resulting in low solidification performance and narrow applicability. Soft soil solidifying agents can be prepared using industrial waste residue, and these agents can even outperform cement. If this technology can be widely applied, approximately 200 million tons of industrial waste residue can be utilized annually with high added value. Researching and developing solidifying agents with industrial waste residue as a partial component can not only reduce the cost of solidifying agents but also achieve better technical results than using cement alone under many working conditions. Furthermore, utilizing industrial waste residue has positive implications for environmental protection and saving land used for waste residue stockpiling.

[0004] A search revealed that Chinese patent application No. 200810019417.7 discloses a soft soil solidifying agent, which consists of a main agent and auxiliary agents. The main agent comprises cement, sand, lime, fly ash, slag, gypsum, and nano-silicon-based oxides, among other components. The auxiliary agents comprise triethanolamine, calcium lignosulfonate, sodium chloride, magnesium chloride, calcium chloride, ferric chloride, vanadium or water glass, polyacrylamide, calcium sulfate, sodium sulfate, and sodium hydroxide, among other components. This solidifying agent enables the resource utilization of industrial solid wastes such as fly ash and slag, and can be used in construction such as cement mixing piles, grouting, jet grouting, shallow subgrade reinforcement, roadbed reinforcement, and compaction. However, its lime content remains relatively high. Summary of the Invention

[0005] 1. The problem to be solved

[0006] The purpose of this invention is to provide a soft soil solidification agent and its application method, which can increase the resource utilization of industrial solid waste, reduce cement usage, and effectively ensure the solidification effect of the soft soil solidification agent.

[0007] 2. Technical Solution

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a soft soil solidification agent composed of the following components in the following weight ratio: m(desulfurized gypsum): m(steel slag powder): m(blast furnace slag powder): m(cement clinker): m(polypropylene fiber): m(magnesium oxide nanomaterials): m(nano silicon) = (10-12): (40-43): (39-41): (4.5-5): (0.3-0.5): (0.3-0.33): (0.3-0.33).

[0010] To address the issues of high production costs and relatively poor mechanical and crack resistance caused by excessive cement content in existing soft soil solidifiers, this application primarily uses desulfurized gypsum, steel slag powder, slag powder, and cement clinker as raw materials, supplemented with certain amounts of polypropylene fiber, magnesium oxide nanomaterials, and nano-silicon. This effectively reduces cement content, enabling the recycling of solid waste resources, reducing solid waste emissions, and achieving energy conservation and environmental protection. Simultaneously, it effectively improves the mechanical and crack resistance of the solidified soil, thus ensuring the solidification effect of the solidifier.

[0011] Polypropylene fibers, under the interaction of friction and cohesion in the soil, can form a spatial network structure within the soil, thereby constraining the displacement and deformation of soil particles and improving the water stability of soft soil. Furthermore, because the fibers bear part of the tensile stress during soil deformation, they can improve the unconfined compressive strength and crack resistance of soft soil. Magnesium oxide nanoparticles and nano-silicon can, on the one hand, undergo exchange reactions with clay minerals in soft soil, reducing the viscosity and plasticity index of the soft soil, thus increasing its strength and stability; on the other hand, because their particle size is much smaller than that of soft soil particles, they can fill the voids between soft soil particles, increasing the density of the soft soil. They can also adsorb onto the surface of soft soil particles, forming a relatively strong bond. Magnesium oxide nanoparticles and nano-silicon can react with calcium ions to generate more stable solidified gel systems such as magnesia and silicates. These solidified gel systems further help improve the durability of solidified soil, making it more resistant to environmental erosion and oxidation.

[0012] This invention optimizes the mass ratio of each component to effectively ensure the mechanical properties and crack resistance of the solidified soil. Furthermore, the solidifying agent is composed of the following components in the following weight ratio: m(desulfurized gypsum): m(steel slag powder): m(blast furnace slag powder): m(cement clinker): m(polypropylene fiber): m(magnesium oxide nanomaterials): m(nano-silicon) = 12:43:40:4.75:0.33:0.33:0.33.

[0013] Furthermore, the polypropylene fibers have a length of 6-10 mm, the magnesium oxide nanomaterials have a particle size between 20-100 nanometers, and the nano-silicon has a particle size between 1-100 nanometers. By optimizing the mass ratio of each component and the sizes of the polypropylene fibers, magnesium oxide nanomaterials, and nano-silicon, a good balance can be effectively achieved between the crack resistance, non-lateral compressive strength, and stability of the solidified soil. Furthermore, the nano-silicon with a particle size between 20-50 nanometers accounts for 60-70% of the mass, and the particle size between 50-100 nanometers accounts for 25-35% of the mass.

[0014] Furthermore, the particle size of the steel slag powder is 450-580 μm. 2 / kg, the particle size of the slag powder is 500-600 μm. 2 / kg.

[0015] Furthermore, the nano-silicon is pre-modified by gradually adding sodium hydroxide solution to the nano-silicon suspension, stirring to allow the nano-silicon surface to fully react with sodium hydroxide, and then centrifuging, filtering and drying to obtain sodium hydroxide-coated modified nano-silicon.

[0016] Sodium hydroxide and silicon undergo a hydrosilylation reaction to produce silicon hydroxide (SiO2·nH2O) and silicate (Na2SiO3). Among the products, silicate is easily soluble in water, while silicon hydroxide has poor solubility and is easy to deposit on the solid surface to form a shell around the core. Therefore, the inner layer of modified nano-silicon is elemental silicon, the middle layer is a silicon hydroxide layer, and the outermost layer is a sodium hydroxide coating.

[0017] By introducing a sodium hydroxide coating onto the surface of nano-silicon, the nano-silicon reacts with sodium hydroxide, significantly altering its surface properties, increasing its hydrophilicity and adhesion, and improving its dispersibility. Simultaneously, the presence of the sodium hydroxide coating further promotes the hydration reaction between nano-silicon and water, accelerating its hardening process and thus increasing the strength and hardness of the soft soil stabilizer. The introduction of the sodium hydroxide coating also enhances the bond between nano-silicon and soil particles, thereby improving the shear strength of the soil.

[0018] Furthermore, the concentration of the sodium hydroxide solution is 1-1.5 mol / L, and the reaction time between sodium hydroxide and nano-silicon is 10-15 min. The concentration of the sodium hydroxide solution and the reaction time affect the degree of reaction between nano-silicon and sodium hydroxide. This application, by strictly controlling the concentration of the sodium hydroxide solution and the reaction time, ensures that the surface of the nano-silicon reacts to form a layer of silicon hydroxide, while preventing excessive reaction and ensuring the effectiveness of the outer sodium hydroxide coating.

[0019] Furthermore, the thickness of the nano-silicon surface coating is 5-10 nm.

[0020] The present invention also provides a method for applying the above-mentioned soft soil solidifying agent, wherein the solidifying agent is added to the soft soil to be solidified and mixed evenly, and the amount of solidifying agent added is 8%-20% of the mass of the soft soil.

[0021] In summary, this application can effectively realize the resource recycling of metallurgical solid wastes such as desulfurized gypsum, steel slag powder, and slag powder, reduce the amount of cement added, and at the same time, with the addition of polypropylene fiber, magnesium oxide nanoparticles and nano-silicon, the mechanical properties of the curing agent can be effectively improved, ensuring its unconfined compressive strength, improving its toughness and density, and reducing the cracking tendency of the solidified soil. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] Example 1

[0024] The soft soil solidifying agent of this embodiment is composed of the following components in the following weight ratio: m(desulfurized gypsum): m(steel slag powder): m(slag powder): m(cement clinker): m(polypropylene fiber): m(magnesium oxide nanomaterials): m(nano silicon) = 12:43:40:4.75:0.33:0.33:0.33.

[0025] In this embodiment, the polypropylene fiber length is 6-10 mm, the magnesium oxide nanomaterial particle size is between 20-100 nm, and the nano-silicon particle size is between 1-100 nm. The nano-silicon particles with a size of 20-50 nm account for 60% of the mass, and the particles with a size of 50-100 nm account for 35% of the mass. The steel slag powder has a particle size of 450-580 nm. 2 / kg, the particle size of slag powder is 500-600 μm. 2 / kg. The desulfurization gypsum used in this embodiment is dihydrate gypsum.

[0026] After the above-mentioned curing agent components are mixed evenly according to the mass ratio, they are added to the soft soil to be cured. The amount of curing agent added is 8% of the mass of the soft soil, and the water-cement ratio is controlled at 0.4, thereby curing the soft soil.

[0027] Example 2

[0028] The soft soil stabilizer in this embodiment has a composition basically the same as in Example 1, with the main difference being the weight ratio of each component: m(desulfurized gypsum):m(steel slag powder):m(blast furnace slag powder):m(cement clinker):m(polypropylene fiber):m(magnesium oxide nanomaterials):m(nano-silicon) = 10:42:41:4.5:0.5:0.3:0.3. The nano-silicon with a particle size between 20-50 nanometers accounts for 70% of the mass, and the particle size between 50-100 nanometers accounts for 25% of the mass.

[0029] After the above-mentioned curing agent components are mixed evenly according to the mass ratio, they are added to the soft soil to be cured. The amount of curing agent added is 10% of the mass of the soft soil, thereby curing the soft soil.

[0030] Example 3

[0031] The soft soil stabilizer in this embodiment has a composition basically the same as in Example 1, with the main difference being the weight ratio of each component: m(desulfurized gypsum):m(steel slag powder):m(blast furnace slag powder):m(cement clinker):m(polypropylene fiber):m(magnesium oxide nanomaterials):m(nano-silicon) = 11:40:39:5:0.4:0.32:0.31. The nano-silicon particles with a size between 20-50 nanometers account for 65% of the mass, and those with a size between 50-100 nanometers account for 28% of the mass.

[0032] After the above-mentioned curing agent components are mixed evenly according to the mass ratio, they are added to the soft soil to be cured. The amount of curing agent added is 20% of the mass of the soft soil, thereby curing the soft soil.

[0033] Example 4

[0034] The composition of the soft soil solidifying agent in this embodiment is basically the same as that in Example 1. The main difference is that the nano-silicon in this embodiment is pre-modified. First, the nano-silicon is poured into the organic solvent chloroform and stirred thoroughly to prepare a nano-silicon suspension, which ensures that the nano-silicon particles are uniformly dispersed. Then, sodium hydroxide solution is gradually added to the nano-silicon suspension and stirred to allow the nano-silicon surface to fully react with the sodium hydroxide. The concentration of the sodium hydroxide solution is 1 mol / L, and the reaction time between sodium hydroxide and nano-silicon is 15 min. After the reaction is completed, the reaction mixture is centrifuged or filtered to separate the nano-silicon coated with sodium hydroxide. Then, the residual organic solvent and water are removed by drying to obtain sodium hydroxide-coated modified nano-silicon (coating thickness of about 8 nm).

[0035] After the above-mentioned curing agent components are mixed evenly according to the mass ratio, they are added to the soft soil to be cured. The amount of curing agent added is 8% of the mass of the soft soil, and the water-cement ratio is 0.4, thereby curing the soft soil.

[0036] Example 5

[0037] The composition of the soft soil solidifying agent in this embodiment is basically the same as that in Example 2. The main difference is that the nano-silicon in this embodiment is pre-modified. First, the nano-silicon is poured into the organic solvent chloroform and stirred thoroughly to prepare a nano-silicon suspension, which ensures that the nano-silicon particles are uniformly dispersed. Then, sodium hydroxide solution is gradually added to the nano-silicon suspension and stirred to allow the nano-silicon surface to fully react with the sodium hydroxide. The concentration of the sodium hydroxide solution is 1.5 mol / L, and the reaction time between sodium hydroxide and nano-silicon is 10 min. After the reaction is completed, the reaction mixture is centrifuged or filtered to separate the nano-silicon coated with sodium hydroxide. Then, the residual organic solvent and water are removed by drying to obtain sodium hydroxide-coated modified nano-silicon (coating thickness of about 10 nm).

[0038] After the above-mentioned curing agent components are mixed evenly according to the mass ratio, they are added to the soft soil to be cured. The amount of curing agent added is 10% of the mass of the soft soil, thereby curing the soft soil.

[0039] Comparative Example 1

[0040] The curing agent in this comparative example does not contain polypropylene fibers, magnesium oxide nanomaterials, and nano-silicon, as in Example 1, but the other components are the same as in Example 1.

[0041] Comparative Example 2

[0042] The curing agent in this comparative example does not contain magnesium oxide nanomaterials and nano-silicon, unlike that in Example 1, but the other components are the same as in Example 1.

[0043] The unconfined compressive strength of the solidified soils in Examples 1-5 and Comparative Examples 1-2 was measured after standard curing, and the results are shown in Table 1 below.

[0044] Table 1. Comparison data of compressive strength of each embodiment and comparative example.

[0045] Unconfined compressive strength / MPa 7d 14d 28d Example 1 2.25 3.15 4.10 Example 2 2.30 3.28 4.25 Example 3 2.52 3.45 4.83 Example 4 2.45 3.40 4.71 Example 5 2.51 3.48 4.85 Comparative Example 1 0.91 0.98 1.14 Comparative Example 2 1.66 2.33 3.83

[0046] As shown in Table 1, the composite addition of desulfurized gypsum, steel slag powder, slag powder, cement clinker, polypropylene fiber, magnesium oxide nanomaterials, and nano-silicon can effectively improve the unconfined compressive strength of the resulting solidified soil. Modification of the nano-silicon further enhances the compressive strength of the solidified soil. Furthermore, the combined addition of polypropylene fiber, magnesium oxide nanomaterials, and nano-silicon also improves the durability and crack resistance of the solidified soft soil. While adding polypropylene fiber alone can also improve the compressive strength and crack resistance of the solidified soil, its effect is limited.

Claims

1. A soft soil stabilizing agent, characterized in that, It consists of components in the following weight ratios: m 脱硫石膏 :m 钢渣微粉 :m 矿渣粉 :m 水泥熟料 :m 聚丙烯纤维 :m 镁氧化物纳米材料 :m 纳米硅 =(10~12):(40~43):(39~41):(4.5~5):(0.3~0.5):(0.3~0.33):(0.3~0.33) The nano-silicon is pre-modified by gradually adding sodium hydroxide solution to the nano-silicon suspension, stirring to allow the nano-silicon surface to fully react with sodium hydroxide, and then centrifuging, filtering and drying to obtain sodium hydroxide-coated modified nano-silicon.

2. The soft soil stabilizing agent according to claim 1, characterized in that, It consists of components in the following weight ratios: m 脱硫石膏 :m 钢渣微粉 :m 矿渣粉 :m 水泥熟料 :m 聚丙烯纤维 :m 镁氧化物纳米材料 :m 纳米硅 = 12:43:40:4.75:0.33:0.33:0.

33.

3. The soft soil stabilizing agent according to claim 1, characterized in that, The polypropylene fiber has a length of 6-10 mm, the magnesium oxide nanomaterial has a particle size of 20-100 nanometers, and the nano-silicon has a particle size of 1-100 nanometers.

4. The soft soil stabilizing agent according to claim 3, characterized in that, The mass percentage of the nano-silicon with a particle size between 20 and 50 nanometers is 60-70%, and the mass percentage of the nano-silicon with a particle size between 50 and 100 nanometers is 25-35%.

5. The soft soil stabilizing agent according to any one of claims 1-4, characterized in that, The particle size of the steel slag powder is 450-580 μm. 2 / kg, the particle size of the slag powder is 500-600 μm. 2 / kg.

6. The soft soil stabilizing agent according to any one of claims 1-4, characterized in that, The concentration of the sodium hydroxide solution is 1-1.5 mol / L, and the reaction time between sodium hydroxide and nano-silicon is 10-15 min.

7. The soft soil stabilizing agent according to claim 6, characterized in that, The thickness of the nano-silicon surface coating is 5-10 nm.

8. A method for applying the soft soil stabilizing agent as described in any one of claims 1-7, characterized in that, Add the curing agent to the soft soil to be cured and mix evenly. The amount of curing agent added is 8%-20% of the mass of the soft soil.