A low-carbon polymer-modified premixed fluidized soil made from solid waste and its preparation method

Abstract

This invention discloses a low-carbon polymer-modified premixed fluid soil made entirely from solid waste. The premixed fluid soil made entirely from solid waste is composed of the following components by weight: 5-10 parts modifier, 5-10 parts activator, 1-5 parts admixture, 1-5 parts retarder, 10-20 parts coal gangue powder, 10-20 parts carbide slag, 10-20 parts bentonite, 35-40 parts fly ash, 35-40 parts slag powder, 100 parts clay powder, 145 parts machined medium sand, and 150 parts water. This invention improves the compressive strength of fluid soil by adding the polymer polyacrylamide to fluid soil. When polyacrylamide is mixed with fluid soil, the active ingredients in the polymer emulsion and the components in the fluid soil undergo a cross-linking reaction to form a more complex network structure, which can significantly improve the dispersion system of the slurry, reduce the repulsive potential energy between particles in the multiphase dispersion, enhance the integrity and stability of the slurry, and make the slurry less prone to segregation when injected into underground rock strata or fissures, thus maintaining good uniformity and fluidity.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to a low-carbon polymer-modified premixed fluidized soil made entirely from solid waste and its preparation method. Background Technology

[0002] Currently, my country possesses various technical means to treat soft soil foundations. Among them, soil stabilization technology has advantages such as fast consolidation speed, good impermeability, simple construction, low construction noise, and minimal impact on nearby buildings. However, it also has problems in actual engineering, mainly manifested in the following ways: In early projects, the choice of stabilizing agent was relatively limited, mainly using cement and lime to solidify the soil, which was highly dependent on the amount of cement or lime used and greatly increased the project cost; the moisture content of ordinary soil stabilization technology is usually selected based on the optimum moisture content of the soil material, but during construction, the material is basically in loose form, making it difficult to mix evenly, resulting in different strengths in different parts and easy to cause uneven settlement; the application of ordinary soil stabilization technology is limited due to the narrow backfill space, deep backfill depth, high construction difficulty, and difficulty in compaction in pipe gallery projects, making it difficult to guarantee the quality of backfilling.

[0003] The above analysis reveals that problems in soil stabilization technology, such as the use of a single stabilizing agent, uneven material mixing, and the difficulty of backfilling in narrow spaces, urgently need to be addressed. Therefore, fluidized solidified soil technology has been further developed. Fluidized solidified soil refers to a new type of geotechnical engineering material with certain strength, water stability, and low permeability, formed by excavating in-situ weak soil, adding soil stabilizing agents, water, and other materials, mixing them evenly, and then pouring or filling and curing it. Generally, solidified soil with a slump greater than 90mm can be called fluidized solidified soil. When the slump is greater than 160mm, pumping can be used, and vibration is generally not required or only slight vibration is needed during pouring. Fluidized solidified soil has good construction convenience and unique technical advantages in filling projects, especially for filling projects in narrow spaces. Among new geotechnical engineering materials, fluidized solidified soil has broad application prospects and has been practically applied in the backfilling project of the pipe corridor foundation trench at Sichuan Tianfu International Airport.

[0004] Meanwhile, with the continuous acceleration of urbanization, the amount of construction waste generated and discharged in cities is also increasing rapidly, making solid waste treatment and utilization a major issue. Alkali-activated inorganic geopolymers such as coal gangue powder, carbide slag, slag powder, and fly ash can all be utilized as solid waste, featuring low cost, high strength, low energy consumption in the preparation process, and low carbon emissions. They can also provide properties similar to silicate cement-based cementitious materials, making them a low-carbon cementitious material. Coal gangue is a complex solid waste with the world's largest stockpile generated during coal mining. Utilizing calcined coal gangue powder to replace cement as a new building material can not only reduce clinker consumption but also synergistically promote the development of the mechanical properties of fluid soil with other solid wastes. Bentonite is an inexpensive clay mineral with montmorillonite as its main component, exhibiting excellent suspension and thixotropic properties in aqueous solutions. To reduce solidification costs and improve environmental benefits, those skilled in the art typically react alkaline solutions with fly ash and coal combustion residue from solid waste to form solidifying agents. For example, Chinese Patent CN116177909 discloses a solidifying agent for tunnel boring machine slurry and its preparation method. However, this solidifying agent reacts slowly with the slurry, failing to meet the on-site operational time requirements, and its improvement on the strength of the solidified soil is limited. Therefore, this invention uses desulfurized gypsum and microsilica powder as activators. The combined effect of these two agents can regulate the gelation time of the fluidized soil and significantly improve the compressive strength of the solidified soil mass. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a low-carbon polymer-modified premixed fluidized soil made from solid waste and its preparation method. By adding the polymer polyacrylamide to the fluidized soil, the compressive strength of the fluidized soil aggregate can be improved. As a high molecular weight compound, polyacrylamide has good adhesion and stability. When polyacrylamide is mixed with fluidized soil, the active ingredients in the polymer emulsion and the components in the fluidized soil undergo a cross-linking reaction to form a more complex network structure. This can significantly improve the dispersion system of the slurry, reduce the repulsive potential energy between particles in the multiphase dispersion, and increase the attractive potential energy between particles. This helps the particles to aggregate and stabilize, and also enhances the integrity and stability of the slurry. This makes the slurry less prone to segregation when injected into underground rock strata or fissures, maintaining good uniformity and fluidity.

[0006] To achieve the above-mentioned objectives, the technical solution provided by this invention patent is as follows:

[0007] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste, wherein the premixed fluid soil is composed of the following components by weight: 5-10 parts modifier, 5-10 parts activator, 1-5 parts admixture, 1-5 parts retarder, 10-20 parts coal gangue powder, 10-20 parts calcium carbide slag, 10-20 parts bentonite, 35-40 parts fly ash, 35-40 parts slag powder, 100 parts clay powder, 145 parts machined medium sand, and 150 parts water.

[0008] Furthermore, the modifier is polyacrylamide, which is a glassy solid, white powder, or granules, and has the molecular formula (C3H5NO). n Its density is 1.302 g / cm³. 3 The solid content of polyacrylamide is 91.2%.

[0009] Furthermore, the activator is desulfurized gypsum and microsilica powder, wherein the particle size of the desulfurized gypsum is less than 0.074 mm, and the microsilica powder is a grayish-white powder with a particle size of 0.2 μm.

[0010] Furthermore, the additive includes calcium carbonate, magnesium carbonate, calcium hydroxide, iron oxide, and silicon dioxide, with the following proportions for each component: calcium carbonate 85.87%, magnesium carbonate 6.53%, calcium hydroxide 3.93%, iron oxide 1.86%, and silicon dioxide 1.81%.

[0011] Furthermore, the retarder is disodium hydrogen phosphate, which is a white powder, analytical grade, with a purity greater than 99%, and has the molecular formula Na2HPO4·12H2O and a molecular weight of 358.1.

[0012] Furthermore, the coal gangue powder is prepared by grinding coal gangue, calcining it at high temperature, and then activating it. The coal gangue powder consists of SiO2 and Al2O3. The calcium oxide content in the carbide slag is greater than 70 wt%.

[0013] Furthermore, the bentonite is sodium-based bentonite, with no less than 95% of the bentonite passing through a 400-mesh sieve, a pH value of 9.3, and an expansion ratio of >80.

[0014] Furthermore, the fly ash fineness is no greater than 2.5%, the slag powder is S95 grade or above; the clay powder is powdered clay obtained by drying, crushing and sieving silty clay; the fineness modulus of the sand in the process is 2.0; and the water is deionized water.

[0015] A method for preparing low-carbon polymer-modified premixed fluidized soil from solid waste, the method specifically includes the following steps:

[0016] S1. Weigh 10-20 parts of coal gangue powder, 10-20 parts of calcium carbide slag, 10-20 parts of bentonite, 35-40 parts of fly ash, 35-40 parts of slag powder, 100 parts of clay powder, 1-5 parts of admixture, 1-5 parts of retarder, 145 parts of machine-made medium sand, and 100 parts of water, and mechanically mix them evenly to obtain slurry A.

[0017] S2, weigh 2-4 parts of desulfurized gypsum, 3-6 parts of microsilica powder and 25 parts of water and stir and mix them evenly to obtain an activator solution. Then add the activator solution to slurry A and mix it evenly under mechanical stirring to obtain slurry B.

[0018] S3, weigh 5-10 parts of polyacrylamide and 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add the modifier solution to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is polymer-modified premixed fluidized soil for solid waste.

[0019] Based on the above technical solution, the present invention patent, a low-carbon polymer-modified premixed fluidized soil for all solid waste and its preparation method, has achieved the following technical effects through practical application:

[0020] 1. This invention relates to a low-carbon polymer-modified premixed fluidized soil made from solid waste. By adding the polymer polyacrylamide to the fluidized soil, the compressive strength of the fluidized soil aggregate can be improved. As a high molecular weight compound, polyacrylamide has good adhesion and stability. When polyacrylamide is mixed with fluidized soil, the active ingredients in the polymer emulsion and the components in the fluidized soil undergo a cross-linking reaction to form a more complex network structure. This can significantly improve the dispersion system of the slurry, reduce the repulsive potential energy between particles in the multiphase dispersion, and increase the attractive potential energy between particles. This helps the particles to aggregate and stabilize, and also enhances the integrity and stability of the slurry. This makes the slurry less prone to segregation when injected into underground rock strata or fissures, maintaining good uniformity and fluidity.

[0021] 2. This invention discloses a low-carbon polymer-modified premixed fluidized soil for solid waste. By using desulfurized gypsum and microsilica as activators, the compressive strength of the fluidized soil aggregate is improved, and the gelation time is adjusted. Under the combined action of sulfate activation by gypsum and alkali activation by microsilica, the silicon-oxygen bonds and aluminum-oxygen bonds in the aluminosilicate raw materials break and recombine. The sulfate ions in the gypsum combine with calcium ions to form ettringite. After the ettringite expands, it combines with the soil, significantly improving the compressive strength of the fluidized soil aggregate. The [SiO4] tetrahedra and [AlO4] tetrahedra in the aluminosilicate material dissolve in an alkaline environment to form [Si(OH)4] and [Al(OH)4]. -Monomers diffuse and penetrate into solid particles based on the principle of chemical equilibrium, polymerizing to form a gel phase, which solidifies into a geopolymer. Active silica (SiO2) and alumina (Al2O3) continuously dissolve and participate in hydration reactions to generate hydrated calcium silicate (CSH) gel and hydraulic ettringite (CaO·Al2O3·3CaSO4·32H2O). This mixture is then evenly mixed with silty clay powder to obtain premixed fluid soil, which further improves the compressive strength of the fluid soil aggregate. Detailed Implementation

[0022] To make the objectives, technical solutions, and effects of this invention clearer, specific examples are provided below. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this invention.

[0023] Example 1

[0024] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste is obtained through the following preparation steps:

[0025] Step 1: Pour 10 parts coal gangue powder, 10 parts carbide slag, 10 parts bentonite, 35 parts fly ash, 35 parts slag powder, 100 parts clay powder, 5 parts admixture, 2.5 parts retarder, and 145 parts machined medium sand into 100 parts water and mix evenly under mechanical stirring to obtain slurry A.

[0026] Step 2: Pour 4 parts of desulfurized gypsum and 6 parts of microsilica powder into 25 parts of water, stir to mix evenly to obtain an activator solution, then add it to slurry A and mix evenly under mechanical stirring to obtain slurry B.

[0027] Step 3: Pour 5 parts of polyacrylamide into 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add it to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is the polymer-modified premixed fluidized soil for solid waste.

[0028] Comparative Example 1

[0029] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste is obtained through the following preparation steps:

[0030] Step 1: Pour 10 parts coal gangue powder, 10 parts carbide slag, 10 parts bentonite, 35 parts fly ash, 35 parts slag powder, 100 parts clay powder, 5 parts admixture, 2.5 parts retarder, and 145 parts machined medium sand into 100 parts water and mix evenly under mechanical stirring to obtain slurry A.

[0031] Step 2: Pour 4 parts of desulfurized gypsum and 6 parts of microsilica powder into 25 parts of water, stir to mix evenly to obtain an activator solution, then add it to slurry A and mix evenly under mechanical stirring to obtain slurry B.

[0032] Step 3: Pour 0 parts of polyacrylamide into 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add it to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is the polymer-modified premixed fluidized soil for solid waste.

[0033] Comparative Example 2

[0034] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste is obtained through the following preparation steps:

[0035] Step 1: Pour 10 parts coal gangue powder, 10 parts carbide slag, 10 parts bentonite, 35 parts fly ash, 35 parts slag powder, 100 parts clay powder, 5 parts admixture, 2.5 parts retarder, and 145 parts machined medium sand into 100 parts water and mix evenly under mechanical stirring to obtain slurry A.

[0036] Step 2: Pour 0 parts of desulfurized gypsum and 0 parts of microsilica powder into 25 parts of water, stir to mix evenly to obtain an activator solution, then add it to slurry A and mix evenly under mechanical stirring to obtain slurry B.

[0037] Step 3: Pour 5 parts of polyacrylamide into 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add it to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is the polymer-modified premixed fluidized soil for solid waste.

[0038] Comparative Example 3

[0039] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste is obtained through the following preparation steps:

[0040] Step 1: Pour 50 parts fly ash, 50 parts slag powder, 100 parts clay powder, 5 parts admixture, 2.5 parts retarder, and 145 parts machined medium sand into 100 parts water and mix evenly under mechanical stirring to obtain slurry A.

[0041] Step 2: Pour 4 parts of desulfurized gypsum and 6 parts of microsilica powder into 25 parts of water, stir to mix evenly to obtain an activator solution, then add it to slurry A and mix evenly under mechanical stirring to obtain slurry B.

[0042] Step 3: Pour 5 parts of polyacrylamide into 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add it to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is the polymer-modified premixed fluidized soil for solid waste.

[0043] Comparative Example 4

[0044] A low-carbon polymer-modified premixed fluid soil made entirely from solid waste is obtained through the following preparation steps:

[0045] Step 1: Pour 50 parts fly ash, 50 parts slag powder, 100 parts clay powder, 5 parts admixture, 2.5 parts retarder, and 145 parts machined medium sand into 100 parts water and mix evenly under mechanical stirring to obtain slurry A.

[0046] Step 2: Pour 0 parts of desulfurized gypsum and 0 parts of microsilica powder into 25 parts of water, stir to mix evenly to obtain an activator solution, then add it to slurry A and mix evenly under mechanical stirring to obtain slurry B.

[0047] Step 3: Pour 0 parts of polyacrylamide into 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add it to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is the polymer-modified premixed fluidized soil for solid waste.

[0048] The weight proportions of each component in Example 1 and Comparative Examples 1-4 are summarized in Table 1.

[0049] Table 1: Parts by weight of each component in Example 1 and Comparative Examples 1-4

[0050] Components Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Modifier 5 0 5 5 0 Activator 10 10 0 10 0 admixtures 5 5 5 5 5 Coal gangue powder 10 10 10 0 0 calcium carbide slag 10 10 10 0 0 Bentonite 10 10 10 0 0 fly ash 35 35 35 50 50 Slag powder 35 35 35 50 50 Retarder 2.5 2.5 2.5 2.5 2.5 clay powder 100 100 100 100 100 Mechanized sand 145 145 145 145 145 water 150 150 150 150 150

[0051] The test data are shown in Table 2.

[0052] Table 2: Detection Data

[0053]

[0054] Implementation results:

[0055] As can be seen from Example 1 and Comparative Example 1, adding polyacrylamide to fluid soil will shorten the gelation time of fluid soil, increase viscosity, and slightly increase the compressive strength of 28-day aggregate. When polyacrylamide is mixed with fluid soil, a cross-linking reaction occurs, forming a more complex network structure, which helps the particles to aggregate and stabilize.

[0056] As can be seen from Example 1 and Comparative Example 2, adding desulfurized gypsum and microsilica to fluid soil will shorten the cementation time of fluid soil, increase viscosity, and significantly increase the compressive strength of the 28-day aggregate.

[0057] As can be seen from Example 1 and Comparative Example 3, replacing fly ash and slag powder with equal amounts of coal gangue powder, carbide slag and bentonite to prepare fluid soil will shorten the cementing time of the fluid soil, maintain the same viscosity, and maintain the same 28-day compressive strength of the aggregate. Coal gangue powder, carbide slag and bentonite can adsorb and exchange ions in the solution to form micelle structure and network structure, control the stability of the slurry, increase the cementing ability and strength of the fluid soil, and maintain the uniformity and dispersibility of the fluid soil.

[0058] Comparative Examples 3 and 4 show that adding polyacrylamide, desulfurized gypsum, and silica fume to fluid soil will shorten the cementation time, increase the viscosity, and significantly increase the compressive strength of the 28-day aggregate.

[0059] The green and low-carbon polymer-modified premixed fluid soil prepared by this invention, through the addition of modifiers and activators to the premixed fluid soil, allows for the synergistic regulation of the gelation time, fluidity, and 28-day compressive strength of the aggregate. This results in improved durability, controllable setting time, good fluidity, high compressive strength of the aggregate, low cost, environmental friendliness, low energy consumption, and ease of preparation.

[0060] The green, low-carbon polymer-modified premixed fluidized soil from all solid waste in this invention can fully utilize construction solid waste. Coal gangue powder, carbide slag, slag powder, and fly ash undergo depolymerization and condensation reactions to form a gel material with fluidity and a certain strength after hardening. This reduces cement usage and building material energy consumption, and decreases carbon dioxide emissions while enhancing the workability of the modified fluidized soil and meeting construction requirements. Bentonite has strong adsorption and water absorption properties, which can increase the viscosity of the fluidized soil and maintain its fluidity. The layered structure of bentonite has ion exchange capacity, which can adsorb and exchange ions in the solution. This ion exchange capacity can control the ion concentration and stability of the mud. At the same time, there are adsorption forces and electrostatic forces between bentonite particles, which can form micelle and network structures, increasing the cementing capacity and strength of the fluidized soil and maintaining its uniformity and dispersibility.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A low-carbon polymer-modified premixed fluid soil made entirely from solid waste, characterized in that, The premixed fluid soil made entirely from solid waste is composed of the following components by weight: 5-10 parts modifier, 5-10 parts activator, 1-5 parts admixture, 1-5 parts retarder, 10-20 parts coal gangue powder, 10-20 parts calcium carbide slag, 10-20 parts bentonite, 35-40 parts fly ash, 35-40 parts slag powder, 100 parts clay powder, 145 parts machined medium sand, and 150 parts water. The modifier is polyacrylamide, which is a glassy solid, white powder, or granules, and has the molecular formula (C3H5NO). n Its density is 1.302 g / cm³. 3 The solid content of polyacrylamide is 91.2%. The activator is desulfurized gypsum and microsilica powder. The particle size of the desulfurized gypsum is less than 0.074 mm, and the microsilica powder is a grayish-white powder with a particle size of 0.2 µm. The additives include calcium carbonate, magnesium carbonate, calcium hydroxide, iron oxide, and silicon dioxide, with the following proportions: calcium carbonate 85.87%, magnesium carbonate 6.53%, calcium hydroxide 3.93%, iron oxide 1.86%, and silicon dioxide 1.81%.

2. The low-carbon polymer-modified premixed fluid soil for all solid waste as described in claim 1, characterized in that, The retarder is disodium hydrogen phosphate, which is a white powder, analytical grade, with a purity greater than 99%. The molecular formula of disodium hydrogen phosphate is Na2HPO4·12H2O, and the molecular weight is 358.

1.

3. The low-carbon polymer-modified premixed fluid soil based on solid waste according to claim 1, characterized in that, The coal gangue powder is prepared by grinding coal gangue, calcining it at high temperature, and then activating it. The coal gangue powder consists of SiO2 and Al2O3. The calcium oxide content in the carbide slag is greater than 70 wt%.

4. The low-carbon polymer-modified premixed fluid soil for all solid waste as described in claim 1, characterized in that, The bentonite is sodium-based bentonite, with no less than 95% of the bentonite passing through a 400-mesh sieve, a pH value of 9.3, and an expansion ratio of >80.

5. The low-carbon polymer-modified premixed fluid soil for all solid waste according to claim 1, characterized in that, The fly ash fineness is no greater than 2.5%, the slag powder is S95 grade or above; the clay powder is powdered clay obtained by drying, crushing and sieving silty clay; the fineness modulus of the sand in the process is 2.0; and the water is deionized water.

6. A method for preparing low-carbon polymer-modified premixed solid waste fluid soil as described in any one of claims 1-5, characterized in that, The method specifically includes the following steps: S1. Weigh 10-20 parts of coal gangue powder, 10-20 parts of calcium carbide slag, 10-20 parts of bentonite, 35-40 parts of fly ash, 35-40 parts of slag powder, 100 parts of clay powder, 1-5 parts of admixture, 1-5 parts of retarder, 145 parts of machine-made medium sand, and 100 parts of water, and mechanically mix them evenly to obtain slurry A. S2, weigh 2-4 parts of desulfurized gypsum, 3-6 parts of microsilica powder and 25 parts of water and stir and mix them evenly to obtain an activator solution. Then add the activator solution to slurry A and mix it evenly under mechanical stirring to obtain slurry B. S3, weigh 5-10 parts of polyacrylamide and 25 parts of water and stir to mix evenly to obtain a modifier solution. Then add the modifier solution to slurry B and mix evenly under mechanical stirring to obtain slurry C. Slurry C is polymer-modified premixed fluidized soil for solid waste.

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