Solid-waste-based fluid-state solidified soil and preparation method thereof

Abstract

The invention discloses solid-waste-based fluid-state solidified soil and a preparation method thereof, and belongs to the technical field of solid waste resource utilization. Raw soil is used as a base material, a curing agent composed of steel slag, granulated blast-furnace slag, gypsum, fly ash, aluminate and other industrial solid waste, a flocculating agent, a conditioning agent, a modifying agent, a stabilizing agent and a soil modifying agent are doped, and then the solid-waste-based fluid-state solidified soil is prepared. Adding water and stirring to form premixed flow-state solidified soil; comprising dry powder and water, and the mass ratio of the water to the dry powder is 0.65-0.75; the dry powder comprises the following components in parts by mass: 80-85 parts of raw soil, 10-15 parts of a curing agent, 2-5 parts of a flocculating agent, 0.5-1.5 parts of a conditioning agent, 1-3 parts of a modifying agent, 0.2-0.4 part of a stabilizing agent and 3-5 parts of a soil modifying agent. The solid-waste-based fluid-state solidified soil prepared by the method has the characteristics of high fluidity, high strength, relatively good water stability, low cost and the like, is beneficial to actual production, and conforms to a green development mode.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to a solid waste-based fluidized solidified soil and a preparation method thereof. Background Art

[0002] Solid waste, especially steel slag, has a low utilization rate and is randomly shelved and landfilled, causing serious environmental pollution and social harm. Using the synergistic effect of various solid wastes to prepare cementitious materials is an effective way to improve the utilization rate of solid waste.

[0003] In the construction of building projects, construction units will inevitably excavate foundation pits and trenches. For foundation pits and trenches with ample working space, construction units currently mostly use plain soil, gray soil or plain concrete for backfilling, and then compact them with machines. However, plain soil is highly dependent on compactors and cannot be operated on narrow working surfaces; gray soil has high requirements for the moisture content of the compaction level and cannot be constructed in the rainy season; and plain concrete is expensive but has a relatively low cost-effectiveness. Therefore, for deep foundation pits, narrow or special-shaped foundation pits, there are various problems with the use of traditional backfill materials, such as the difficulty of compacting the backfill with machines, and the layered backfilling not only has low construction efficiency, but also the backfill quality is difficult to guarantee. Therefore, in order to improve the backfill quality of narrow spaces in municipal and construction projects, a new material has been developed - fluidized solidified soil.

[0004] At present, the curing agents used to prepare fluidized solidified soil are mainly cement and lime. The preparation of fluidized solidified soil with cement as the main curing agent has high curing cost, high production energy consumption and high carbon emissions; while the fluidized solidified soil prepared with lime as the main curing agent has low strength, poor stability and easy cracking. Therefore, it is particularly important to use the composite synergistic effect of various solid wastes such as steel slag and slag to prepare a solid waste-based fluidized solidified soil with good stability, low cost and green environmental protection, so as to maximize the utilization of solid waste resources. Summary of the invention

[0005] In order to solve the problems of low strength, poor stability and high cost of fluidized solidified soil prepared by traditional solidifying agents, the present invention provides a solid waste-based fluidized solidified soil and a preparation method thereof.

[0006] The present invention provides a solid waste-based fluidized solidified soil, wherein the raw materials for preparing the solid waste-based fluidized solidified soil include dry powder and water, and the mass ratio of water to dry powder is 0.65-0.75;

[0007] The dry powder comprises the following components by mass: 80-85 parts of raw soil, 10-15 parts of curing agent, 2-5 parts of flocculant, 0.5-1.5 parts of regulator, 1-3 parts of improver, 0.2-0.4 parts of stabilizer and 3-5 parts of soil amendment.

[0008] Preferably, the raw soil is marine silt, natural soil or gravel soil, obtained after crushing; the particle size of the raw soil is not greater than 10 mm.

[0009] Preferably, the curing agent contains the following components by weight: 22 to 35 parts of steel slag, 25 to 35 parts of granulated blast furnace slag powder, 14 to 18 parts of gypsum, 10 to 20 parts of fly ash, and 3 to 5 parts of aluminate.

[0010] Preferably, the steel slag used is steel slag powder having a basicity coefficient of 1.8 or more;

[0011] Preferably, the granulated blast furnace slag powder used has a specific surface area of ​​400m 2 / kg, granulated blast furnace slag powder with a 28d activity index of more than 95%; the gypsum used is desulfurized gypsum or phosphogypsum, the dihydrate gypsum content in the gypsum used is not less than 80.0%, and the particle size is 200-325 mesh; the fly ash used is fly ash with a loss on ignition of not more than 8.0% and a 28d activity index of more than 70%; the aluminate used is sodium metaaluminate.

[0012] Preferably, the flocculant is CaAl2O4.

[0013] Preferably, the regulator is polycarboxylate water-reducing agent powder or naphthalenesulfonate formaldehyde polymer powder.

[0014] Preferably, the stabilizer used is a concentrated solution of tyranase with a pH value of 3.3 to 5.2 and a concentration of 0.9 to 1.2 g / mL.

[0015] Preferably, the modifier is industrial grade sodium polyacrylate, which is a colorless and odorless white powder with a pH of 7.7, a particle size of 200-400 mesh, and a molecular weight of 10 million g / mol.

[0016] Preferably, the soil amendment is zeolite powder with a particle size of 200-325 mesh and a calcium exchange capacity of ≥90.

[0017] The present invention also provides a method for preparing solid waste-based fluidized solidified soil, comprising the following steps:

[0018] Step 1: crush the raw soil and remove foreign matter from the soil, pass it through a 10mm soil sieve, and take the particles under the sieve;

[0019] Step 2: Weigh each component and water in the dry powder according to weight;

[0020] Step 3: dissolve the stabilizer in the dry powder in water and stir evenly; mix the components in the dry powder except the stabilizer, stir evenly, add into the water containing the stabilizer, stir for more than 180 seconds, and obtain solid waste-based fluidized solidified soil.

[0021] Compared with the prior art, the present invention is beneficial in that:

[0022] The solid waste-based fluidized solidified soil described in the present invention uses a large amount of solid wastes such as steel slag, slag, gypsum, fly ash, and aluminate as raw materials. The steel slag has a high utilization rate, which can solve the problems of long-term storage of steel slag occupying land and polluting the environment, thereby realizing the resource utilization of solid waste materials and conforming to the green development model. The fluidized solidified soil prepared by the curing agent of the present invention has the characteristics of simple preparation method, high strength, good stability, low cost, and is conducive to actual production. It effectively solves the problems of low strength, poor stability, high cost, and high carbon emissions of the fluidized solidified soil prepared by traditional curing agents, and does not require manual compaction during construction, which greatly reduces the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0024] Figure 2 This is a scanning electron microscope image of the fluidized solidified soil of Example 4 of the present invention.

[0025] Figure 3 This is a scanning electron microscope image of the fluidized solidified soil of comparative example 3 of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below through embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0027] Sources of various raw materials in the embodiments of the present invention:

[0028] The raw soil is formed by crushing and screening the marine silt from Yancheng City, Jiangsu Province, and the particle size is no more than 10 mm;

[0029] The steel slag is steel slag powder with a basicity coefficient of more than 1.8, provided by Nantong Yongcheng Huihai Construction Engineering Co., Ltd.;

[0030] The specific surface area of ​​slag is 400m 2 / kg, granulated blast furnace slag powder with a 28d activity index of more than 95%, provided by Lanke Environmental Protection Water Purification Material Factory;

[0031] Fly ash with a loss on ignition of no more than 8.0% and a 28-day activity index of more than 70% is provided by Lanke Environmental Protection Water Purification Material Factory;

[0032] The gypsum used is desulfurized gypsum or phosphogypsum, the content of dihydrate gypsum in the gypsum used is not less than 80.0%, the particle size is 200-325 mesh, and it is produced by Chengdu Kelong Reagent Factory;

[0033] Sodium aluminate is a chemical reagent produced by Chengdu Kelong Reagent Factory;

[0034] Flocculant CaAl2O4 is a chemical reagent provided by Yangzhou Yangtai Medical Instrument Co., Ltd.;

[0035] The regulator is a polycarboxylate water reducer or a naphthalenesulfonate formaldehyde polymer, produced by Jiangsu Subote New Materials Co., Ltd.;

[0036] The modifier was industrial grade sodium polyacrylate, provided by Pegasus Biotechnology Co., Ltd., with a pH of 7.7, a particle size of 200-400 mesh, and a molecular weight of 10 million g / mol;

[0037] The stabilizer is a 1g / mL taurase concentrate with a pH of about 4.5, which is made in the laboratory;

[0038] The soil amendment is zeolite powder, which is provided by Henan Borun Casting Materials Co., Ltd., with a particle size of 200-325 mesh and a calcium exchange capacity of ≥90.

[0039] P·O 42.5 cement, provided by Taizhou Yangwan Conch Cement Co., Ltd.

[0040] Example 1

[0041] In this embodiment, the raw materials for preparing the solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.7. The dry powder includes the following in parts by weight:

[0042] 85 parts of raw soil, 12 parts of curing agent, 2 parts of CaAl2O4 as flocculant, 0.5 parts of polycarboxylate water reducer as regulator, 3 parts of industrial grade sodium polyacrylate, 0.2 parts of Tairan enzyme concentrate, 3 parts of zeolite powder. The curing agent includes 22 parts of steel slag, 35 parts of granulated blast furnace slag powder, 18 parts of gypsum, 20 parts of fly ash, and 5 parts of sodium aluminate by weight.

[0043] Preparation method of solid waste based fluidized solidified soil Figure 1 As shown, the following steps are included:

[0044] Step 1: crush the raw soil and remove foreign matter from the soil, pass it through a 10mm soil sieve, and take the particles under the sieve;

[0045] Step 2: Weigh each component and water in the dry powder according to weight;

[0046] Step 3: Dissolve the stabilizer in the dry powder in water and stir evenly; mix the components in the dry powder except the stabilizer, stir evenly, add into the water containing the stabilizer, stir for more than 180 seconds, stir evenly until the fluidity is greater than 100mm, and obtain solid waste-based fluidized solidified soil.

[0047] Example 2

[0048] In this embodiment, the preparation method of solid waste-based fluidized solidified soil is the same as that in Embodiment 1.

[0049] The raw materials for preparing solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.65. The dry powder includes the following in parts by weight:

[0050] 80 parts of raw soil, 15 parts of curing agent, 5 parts of CaAl2O4, 1 part of naphthalenesulfonate formaldehyde polymer, 3 parts of industrial grade sodium polyacrylate, 0.2 parts of tyranase, 4 parts of zeolite powder. The curing agent includes the following components by mass percentage: 35 parts of steel slag, 28 parts of granulated blast furnace slag powder, 14 parts of gypsum, 20 parts of fly ash, and 3 parts of sodium aluminate.

[0051] Example 3

[0052] In this embodiment, the preparation method of solid waste-based fluidized solidified soil is the same as that in Embodiment 1.

[0053] The raw materials for preparing solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.7. The dry powder includes the following in parts by weight:

[0054] 85 parts of raw soil, 12 parts of curing agent, 5 parts of CaAl2O4, 1 part of naphthalenesulfonate formaldehyde polymer, 3 parts of industrial grade sodium polyacrylate, 0.2 parts of tyranase, 5 parts of zeolite powder. The curing agent includes the following components by mass percentage: 35 parts of steel slag, 25 parts of granulated blast furnace slag powder, 18 parts of gypsum, 19 parts of fly ash, and 3 parts of sodium aluminate.

[0055] Example 4

[0056] In this embodiment, the preparation method of solid waste-based fluidized solidified soil is the same as that in Embodiment 1.

[0057] The raw materials for preparing solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.7. The dry powder includes the following in parts by weight:

[0058] Raw soil: 80 parts, curing agent 15 parts, CaAl2O4 3 parts, polycarboxylate water reducer 0.5 parts, industrial grade sodium polyacrylate 1 part, tyranase 0.2 parts, zeolite powder 4 parts. The curing agent includes the following components by mass percentage: 35 parts of steel slag, 35 parts of granulated blast furnace slag powder, 16 parts of gypsum, 10 parts of fly ash, and 4 parts of sodium aluminate.

[0059] Example 5

[0060] In this embodiment, the preparation method of solid waste-based fluidized solidified soil is the same as that in Embodiment 1.

[0061] The raw materials for preparing solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.75. The dry powder includes the following in parts by weight:

[0062] 85 parts of raw soil, 12 parts of curing agent, 4 parts of CaAl2O4, 1.0 parts of polycarboxylate water reducer, 2 parts of industrial grade sodium polyacrylate, 0.4 parts of tyranase, 3 parts of zeolite powder. The curing agent includes the following components by mass percentage: 32 parts of steel slag, 33 parts of granulated blast furnace slag powder, 15 parts of gypsum, 15 parts of fly ash, and 5 parts of sodium aluminate.

[0063] Example 6

[0064] In this embodiment, the preparation method of solid waste-based fluidized solidified soil is the same as that in Embodiment 1.

[0065] The raw materials for preparing solid waste-based fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.75. The dry powder includes the following in parts by weight:

[0066] 80 parts of raw soil, 14 parts of curing agent, 4 parts of CaAl2O4, 0.7 parts of polycarboxylic acid water reducer, 3 parts of industrial grade sodium polyacrylate, 0.3 parts of tyranase, 5 parts of zeolite powder. The curing agent includes by weight: 25 parts of steel slag, 35 parts of granulated blast furnace slag powder, 17 parts of gypsum, 18 parts of fly ash, and 5 parts of sodium aluminate.

[0067] Comparative Example 1

[0068] This comparative example provides a fluidized solidified soil, which is different from Example 3 in that it does not contain tyranase and other components remain unchanged.

[0069] The raw materials for preparing fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.7. The dry powder includes the following in parts by weight:

[0070] Raw soil: 85 parts, curing agent: 12 parts, CaAl2O4: 5 parts, naphthalenesulfonate formaldehyde polymer: 1 part, industrial grade sodium polyacrylate: 3 parts, zeolite powder: 5 parts. The curing agent includes: 35 parts of steel slag, 25 parts of granulated blast furnace slag powder, 18 parts of gypsum, 19 parts of fly ash, and 3 parts of sodium aluminate.

[0071] Comparative Example 2

[0072] This comparative example provides a fluidized solidified soil, which is different from Example 4 in that the solidifying agent does not contain aluminate, and the other components remain unchanged.

[0073] The raw materials for preparing fluidized solidified soil are water and dry powder, with a water-to-solid ratio of 0.7.

[0074] The dry powder includes, by weight: 80 parts of raw soil, 15 parts of curing agent, 3 parts of CaAl2O4, 0.5 parts of polycarboxylic acid water reducer, 1 part of industrial grade sodium polyacrylate, 0.2 parts of tyranase, and 4 parts of zeolite powder. The curing agent includes the following components by mass percentage: 35 parts of steel slag, 35 parts of granulated blast furnace slag powder, 16 parts of gypsum, and 10 parts of fly ash.

[0075] Comparative Example 3

[0076] This comparative example provides a fluidized solidified soil, which is different from Example 4 in that P·O 42.5 cement is used as a solidifying agent, and other components remain unchanged.

[0077] The raw materials for preparing a fluidized solidified soil are water and dry powder, the water-to-solid ratio is 0.7, and the dry powder includes the following in parts by weight:

[0078] 80 parts of raw soil, 15 parts of curing agent, 3 parts of CaAl2O4, 0.5 parts of polycarboxylate water reducer, 1 part of industrial grade sodium polyacrylate, 0.2 parts of tyranase, 4 parts of zeolite powder. The curing agent includes the following components by mass percentage: 100 parts of P·O 42.5 cement.

[0079] The solidified soils prepared in Examples 1 to 6 and Comparative Examples 1 to 3 of the present invention are tested for slump / expansion and compressive strength according to the corresponding requirements of the standard "Technical Standard for Premixed Fluidized Solidified Soil Filling" T / CEWCS-2022 of the China Association for Engineering Standardization. The standard requires that the slump of voids and backfills be 150 to 240 mm, and the 28d compressive strength is determined according to engineering needs and is not less than 0.4 MPa. The test results are shown in Table 1.

[0080] Water stability is an important indicator for evaluating the durability of solidified soil. The water stability test was carried out on the solid waste-based fluidized solidified soil provided in Examples 1 to 6 and Comparative Examples 1 to 3 of the present application. The test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] The results in Table 1 show that as the water-solid ratio increases, the fluidity of the solidified soil increases. This is because the dispersion of free water in the mixture destroys the original bonding and friction resistance between soil particles, increases the spacing between soil particles, and the free water filled between soil particles forms a water film, which plays a lubricating role; but after the water-solid ratio reaches 0.7, the strength of the solidified soil decreases as the water-solid ratio increases. This is because the amount of water used exceeds the water required for the hydration of the curing agent, and water seepage will occur. The water will evaporate during the curing process, leaving pores and reducing the density, thereby reducing the strength of the solidified soil. The strength of the solidified soil increases with the increase in the amount of curing agent. As the amount of curing agent increases, the products generated by the hydration reaction increase, the solidified soil will be denser, the strength will be higher, the water stability coefficient will be larger, and the durability will be better.

[0084] Compared with Example 3, in Comparative Example 1, without tyranase, the decomposition rate of organic matter in the soil slows down, the membrane and friction between soil particles cannot be reduced, the pore permeability increases, and the compressive strength cannot be improved.

[0085] Compared with Example 4, Comparative Example 2 does not have aluminate. The addition of aluminate can promote the hydration of C2S in steel slag, and it is very easy to react with gypsum to form calcium sulfate. The lack of aluminate reduces the strength, indicating that the hydration reaction of steel slag is not effectively carried out, and the generation of hydration products is reduced, resulting in low strength of the solidified soil, small water stability coefficient, and poor durability. Compared with Example 4, the strength of Comparative Example 3 is lower than that of Example 4. Figure 2 and Figure 3 As shown, Example 4 generates a large amount of calcium sulfoxide and CSH gel, while Comparative Example 3 generates only a small amount, and the structural density is lower than that of Example 4, indicating that compared with cement-based fluidized solidified soil, the strength and water stability of solid waste-based fluidized solidified soil are better than those of cement-based fluidized solidified soil, and the cost is much lower than that of pure cement fluidized solidified soil.

[0086] In the early stage of hydration, CaO, FeO, MgO and other substances in the slag and gypsum provide an alkaline environment for the system. - The aluminate can promote the hydration of C2S in the steel slag, and make full use of the hydration synergistic reaction between steel slag, slag, gypsum, fly ash and aluminate to generate dense structured ettringite and CSH gel. The needle-shaped ettringite connects the cementitious material and soil particles to form a skeleton, filling the gaps between the raw soil particles, and the meshed CSH gel covers the cementitious material and the particle surface, forming a relatively dense microstructure. The precipitation and purification effect of flocculant CaAl2O4 is used to promote the rapid aggregation reaction of particles and curing agents, thereby improving the early strength of fluidized solidified soil; the adjustment of polycarboxylic acid water-reducing agent powder and naphthalenesulfonate formaldehyde polymer powder as surfactants can significantly improve the fluidity of solidified soil, and fluidized solidified soil has the characteristics of large fluidity; the catalytic activity reaction of stabilizer teranase accelerates the decomposition and metabolism rate of organic matter in the soil and reduces the pore permeability; the modifier sodium polyacrylate can promote the aggregation of soil, bond the dispersed soil particles into larger aggregates, and the numerous aggregate structures are tightly bonded together by hydrogel, so that the dispersed granular soil becomes continuous and forms a stable soil structure. The soil amendment zeolite powder has a porous structure, which can absorb more water molecules, increase the water retention of the soil, and modify the physical properties of the soil, providing internal maintenance for fluidized solidified soil, and significantly improving its later strength.

[0087] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention.

Claims

1. A solid waste-based fluidized solidified soil, characterized in that: The raw materials for preparing the solid waste-based fluidized solidified soil include dry powder and water, and the mass ratio of water to dry powder is 0.65-0.75; The dry powder comprises the following components by mass: 80-85 parts of raw soil, 10-15 parts of solidifying agent, 2-5 parts of flocculant, 0.5-1.5 parts of regulator, 1-3 parts of improver, 0.2-0.4 parts of stabilizer, and 3-5 parts of soil amendment.

2. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The raw soil is obtained by crushing marine silt, natural soil or gravel soil; the organic matter content in the raw soil is not more than 5%, and the particle size of the raw soil is not more than 10 mm.

3. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The curing agent contains the following components by weight: 22-35 parts of steel slag, 25-35 parts of granulated blast furnace slag powder, 14-18 parts of gypsum, 10-20 parts of fly ash, and 3-5 parts of aluminate.

4. The solid waste-based fluidized solidified soil according to claim 3, characterized in that: The steel slag used is steel slag powder with a basicity coefficient of more than 1.8; The granulated blast furnace slag powder used has a specific surface area greater than 400m 2 / kg, granulated blast furnace slag powder with a 28d activity index of more than 95%; The gypsum used is desulfurized gypsum or phosphogypsum, the content of dihydrate gypsum in the gypsum used is not less than 80.0%, and the particle size is 200-325 meshes; The fly ash used is fly ash with a loss on ignition of no more than 8.0% and a 28d activity index of more than 70%; The aluminate used was sodium metaaluminate.

5. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The flocculant is CaAl2O4.

6. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The regulator is polycarboxylate water-reducing agent powder or naphthalenesulfonate formaldehyde polymer powder.

7. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The stabilizer used is a concentrated solution of tyranase with a pH value of 3.3 to 5.2 and a concentration of 0.9 to 1.2 g / mL.

8. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The modifier is sodium polyacrylate, with a pH of 7.7, a particle size of 200-400 meshes, and a molecular weight of 10 million g / mol.

9. The solid waste-based fluidized solidified soil according to claim 1, characterized in that: The soil amendment is zeolite powder with a particle size of 200-325 meshes and a calcium exchange capacity of ≥90.

10. The method for preparing solid waste-based fluidized solidified soil according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: crush the raw soil and remove foreign matter from the soil, pass it through a 10mm soil sieve, and take the particles under the sieve; Step 2: Weigh each component and water in the dry powder according to weight; Step 3: dissolve the stabilizer in the dry powder in water and stir evenly; mix the components in the dry powder except the stabilizer, stir evenly, add into the water containing the stabilizer, stir for more than 180 seconds, and obtain solid waste-based fluidized solidified soil.

Images