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

Abstract

The invention provides solid-waste-based fluid-state solidified soil and a preparation method of the solid-waste-based fluid-state solidified soil. The solid waste-based flow state solidified soil comprises a filling material, a framework material and a reinforcing material, the filling material comprises the following components in parts by weight: 60-95 parts of engineering residue soil, 5-40 parts of alkaline waste residues, 5-30 parts of a cementing material, 1-10 parts of a polymer emulsion, 0.5-3 parts of silica fume, 0.1-1 part of cellulose ether, 0.1-1 part of a compound water reducing agent and 0.5-2 parts of an exciting agent. The framework material comprises waste concrete blocks and / or waste brick blocks; the reinforcing material comprises a waste safety net and / or fiber gridding cloth. The flow-state solidified soil can achieve rapid backfilling in a narrow space, is excellent in shrinkage cracking resistance and impermeability, simple in preparation method and convenient to apply and construct, effectively solves the problems that the flow-state solidified soil is large in shrinkage, prone to cracking and the like, improves the quality of a backfilling project, achieves in-situ resource utilization of construction waste, and reduces the construction cost. And the construction cost of engineering can be reduced, and the problems of land occupation, environment pollution and the like caused by solid waste stacking are reduced.

Description

Technical Field

[0001] The present invention relates to the technical fields of solid waste treatment and civil engineering materials, and particularly to a solid waste-based fluidized solidified soil and a preparation method thereof. Background Art

[0002] Fluidized solidified soil is a filling material mainly composed of engineering muck and a curing agent, which is stirred with water until uniform to form a filling material with good fluidity and can be used for engineering backfilling such as backfilling of foundation trenches, goafs, foundation pit trenches, pipe galleries, etc. Compared with the traditional manual ramming backfilling process, fluidized solidified soil has the advantages of fast construction speed and high strength. However, since the main raw material of fluidized solidified soil is clay, which has characteristics such as high viscosity and strong water adsorption capacity, in order to obtain fluidized solidified soil with good fluidity, the mixing water consumption far exceeds the water consumption required for the hydration of the curing agent, resulting in serious problems such as severe bleeding, large dry shrinkage, and easy cracking after the fluidized solidified soil is filled, seriously affecting the engineering quality.

[0003] Therefore, it is of great significance to develop a fluidized solidified soil with large fluidity, low bleeding rate, small dry shrinkage, and not easy to crack. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the first object of the present invention is to provide a solid waste-based fluidized solidified soil. This fluidized solidified soil uses construction waste and industrial solid waste as the main raw materials, can realize the rapid backfilling of projects such as foundation trenches, goafs, foundation pit trenches, pipe galleries, etc., and has a low bleeding rate, small dry shrinkage, and is not easy to crack.

[0005] The second object of the present invention is to provide a preparation method of the solid waste-based fluidized solidified soil. This method is simple, low in cost, and easy to construct and apply.

[0006] In order to achieve the above technical object, the present invention provides a solid waste-based fluidized solidified soil, which includes a filling material, a skeleton material, and a reinforcing material;

[0007] The filling material includes the following components in parts by weight: 60 - 95 parts of engineering muck, 5 - 40 parts of alkaline waste residue, 5 - 30 parts of cementitious material, 1 - 10 parts of polymer emulsion, 0.5 - 3 parts of silica fume, 0.1 - 1 part of cellulose ether, 0.1 - 1 part of compound water reducer, 0.5 - 2 parts of activator;

[0008] The skeleton material includes waste concrete blocks and / or waste brick blocks;

[0009] The reinforcing material includes waste safety nets and / or fiber mesh cloths.

[0010] First, the filling material of the present invention uses construction waste soil as the main raw material. By adding alkaline waste residue, the hydration activity of clay mineral components in the waste soil and active components in the cementitious material is stimulated. The cementitious material undergoes hydration reaction first, generating cementitious substances such as C-S-H, C-A-H, C-A-S-H, and N-A-S-H, which can cement the waste soil particles together, enabling the filling material to form relatively high strength. At the same time, a large amount of Ca 2+ , Mg 2+ , Fe 3+ , Al 3+ and other high-valent cations are dissolved from the active components in the cementitious material. These cations can perform ion exchange with Na + , K + etc. adsorbed on the surface of clay particles, reducing the thickness of the double electric layer on the surface of clay particles, increasing the interaction force between clay particles, promoting the agglomeration of clay particles, and being beneficial to improving the strength of the filling material. In addition, the clay mineral components react with cementitious substances such as C-S-H, C-A-H, C-A-S-H, and N-A-S-H under the action of alkaline waste residue to generate sheet-like, fibrous or needle-like crystals, further increasing the connection between waste soil particles and cementitious substances and forming a stable coagulation network structure. Secondly, the waste concrete blocks and brick blocks in the skeleton material have a high water absorption rate. They can absorb excess water in the initial stage of filling, reduce the bleeding of fluidized solidified soil, and release water in the later stage to ensure the full hydration of the cementitious material, playing a good water retention effect and internal curing role. This can improve the early and late strength of the fluidized solidified soil and reduce its drying shrinkage and cracking. At the same time, the skeleton material contains unhydrated cement particles, cement hydration product Ca(OH)2, calcined clay minerals, etc., which have certain hydration activity and can undergo cross-linking reactions with waste soil and cementitious materials, thus forming a stable three-dimensional network structure. In addition, the skeleton material also has relatively high strength. When lapped together, it forms a skeleton structure, enhancing the bearing capacity of the solidified soil while restricting its shrinkage. Thirdly, the reinforcing materials are mainly waste safety nets and fiber mesh cloths. Laying them on the surface of the filling material can resist the internal stress generated by the shrinkage of the solidified soil, thereby enhancing its anti-shrinkage and cracking performance. Compared with natural stones, the waste concrete blocks and brick blocks in the present invention have a high water absorption rate and contain characteristics such as unhydrated cement particles, cement hydration product Ca(OH)2, calcined clay minerals, etc. Therefore, they can interact with the filling material in the present invention and play a promoting role in the curing of the solidified soil.

[0011] As a preferred solution, the filling material comprises the following components in parts by weight: 65 - 85 parts of construction waste soil, 15 - 35 parts of alkaline waste residue, 8 - 20 parts of cementitious material, 3 - 8 parts of polymer emulsion, 0.5 - 1.5 parts of silica fume, 0.1 - 0.5 parts of cellulose ether, 0.1 - 0.5 parts of compound water reducer, and 0.5 - 1.5 parts of activator.

[0012] As a preferred solution, the main components of the construction waste soil include SiO2 and Al2O3.

[0013] As a preferred solution, the construction waste soil includes at least one of foundation pit soil, shield soil, and slurry generated during construction project construction.

[0014] As a preferred solution, the alkaline waste residue includes alkali residue and / or carbide slag.

[0015] As a preferred solution, the alkali residue is an industrial solid waste generated by ammonia-alkali method for soda production, and its main mineral components are CaCO3, CaSO4, and CaCl2.

[0016] As a preferred solution, the specific surface area of the alkali residue is not less than 300m 2 / kg.

[0017] As a preferred solution, the carbide slag is an alkaline waste residue generated by hydrolysis of calcium carbide during industrial production of polyvinyl chloride, and its main mineral component is Ca(OH)2.

[0018] As a preferred solution, the specific surface area of the carbide slag is not less than 300m 2 / kg.

[0019] As a preferred solution, the cementitious material includes at least one of cement, blast furnace slag, fly ash, steel slag, tungsten tailings, lithium slag, and red mud.

[0020] As a preferred solution, the cement includes at least one of portland cement, sulphoaluminate cement, and aluminate cement.

[0021] As a preferred solution, the specific surface area of the blast furnace slag is not less than 400m 2 / kg.

[0022] As a preferred solution, the specific surface area of the fly ash is not less than 300m 2 / kg.

[0023] As a preferred solution, the specific surface area of the steel slag is not less than 400m 2 / kg.

[0024] As a preferred solution, the specific surface area of the tungsten tailings is not less than 400m 2 / kg.

[0025] As a preferred solution, the specific surface area of the lithium slag is not less than 400m 2 / kg.

[0026] As a preferred embodiment, the specific surface area of the red mud is not less than 300 m 2 / kg.

[0027] As a preferred embodiment, the specific surface area of the silica fume is not less than 15 m 2 / g.

[0028] As a preferred embodiment, the polymer emulsion includes VAE emulsion and / or polyvinyl alcohol emulsion.

[0029] As a preferred embodiment, the solid content of the polymer emulsion is not less than 50 wt%.

[0030] As a preferred embodiment, the cellulose ether includes at least one of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0031] As a preferred embodiment, the compound water reducer includes polymethyl methacrylate-methacrylic acid copolymer and sodium salt.

[0032] As a preferred embodiment, the sodium salt includes at least one of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate, and sodium oxalate.

[0033] As a preferred embodiment, the activator includes at least one of NaOH, Na2SiO3, Na2SO4, and Na2CO3.

[0034] The present invention also provides a method for preparing solid waste-based fluidized solidified soil. The method is to first mix engineering muck with water to obtain finished slurry; then mix the finished slurry with alkaline waste residue, cementitious material, polymer emulsion, silica fume, cellulose ether, compound water reducer, and activator to obtain filling material; and then mix the filling material with skeleton material and lay a reinforcing material on the surface after filling, thus obtaining the solidified soil.

[0035] The present invention utilizes the good fluidity of the filling material to achieve rapid backfilling in narrow spaces; by mixing and filling with skeleton material and filling material, the bearing capacity of the solidified soil is improved and its drying shrinkage is reduced; by laying a reinforcing material on the filling surface, the crack resistance of the solidified soil is improved. The present invention effectively solves the problems of large drying shrinkage and easy cracking of fluidized solidified soil by constructing a skeleton structure for the filling material and adding a surface crack-resistant protective layer, improving its comprehensive performance and the quality of engineering backfilling.

[0036] As a preferred embodiment, the apparent density of the finished slurry is not less than 1350 kg / m 3 .

[0037] As a preferred embodiment, the apparent density of the filling material is not less than 1500 kg / m 3。

[0038] As a preferred solution, the 28-day compressive strength of the filling material is not less than 0.4 MPa.

[0039] As a preferred solution, the size of the skeleton material is 5 mm to 300 mm, and more preferably 5 mm to 25 mm.

[0040] As a preferred solution, the volume ratio of the skeleton material is 20% to 60%, and more preferably 40% to 60%.

[0041] As a preferred solution, the single-layer filling height does not exceed 1000 mm.

[0042] The application construction method of the solid waste-based fluidized solidified soil of the present invention includes the following steps:

[0043] (1) Foundation trench treatment: First, clean the bottom of the foundation trench, then mark the backfill height of the foundation trench and measure this height, and then make baffles or retaining walls according to the measured height;

[0044] (2) Preparation of filling material: First, soak the construction waste soil in water to soften it, sieve it through a 50-mm aperture sieve mesh, then add water and stir and then sieve it through a 5-mm aperture sieve mesh to obtain the finished slurry; then mix the finished slurry with alkaline waste residue, cementitious material, polymer emulsion, silica fume, cellulose ether, compound water reducer and activator to obtain the filling material;

[0045] (3) Filling of fluidized solidified soil: Adopt layered and segmented filling. For each layer, first fill the filling material, then fill the skeleton material, and then tamp it densely with a vibrating rod to ensure that the skeleton material is completely wrapped by the filling material; after the top layer is filled, lay the reinforcing material and apply pressure to the reinforcing material to immerse it in the filling material;

[0046] (4) Curing: After each layer is filled or after the top layer is filled, the solidified soil should be cured.

[0047] As a preferred solution, the maximum size of the skeleton material does not exceed 1 / 4 of the width of the foundation trench.

[0048] As a preferred solution, the skeleton material is filled before the filling material solidifies.

[0049] As a preferred solution, the curing method is watering or covering for moisture preservation.

[0050] As a preferred solution, the curing time of the top layer of solidified soil shall not be less than 7 days.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] (1) The present invention uses a combination of filling materials, skeleton materials, and reinforcing materials for backfill construction. Utilizing the good fluidity of the filling materials, rapid backfill of narrow spaces can be achieved. Then, by filling the skeleton materials in the filling materials, the bearing capacity of the solidified soil is increased, and its drying shrinkage is reduced. And by laying the reinforcing materials on the filling surface, the crack resistance of the filling materials is enhanced. By constructing a skeleton structure in the filling materials and adding a crack-resistant protective layer to its surface, the problems of large drying shrinkage and easy cracking of the fluidized solidified soil are effectively solved, and its comprehensive performance and the quality of engineering backfill are improved.

[0053] (2) In the fluidized solidified soil of the present invention, the filling materials mainly use construction waste soil as the main raw material, the skeleton materials mainly use waste concrete blocks, waste brick blocks, etc., and the reinforcing materials mainly use waste safety nets. Its main raw materials are all construction waste. Therefore, using the fluidized solidified soil of the present invention for backfill construction can realize the in-situ resource utilization of construction waste, not only can alleviate problems such as the occupation of land and environmental pollution caused by the landfill of construction waste, but also can reduce the consumption of natural resources and lower the construction cost of the project.

[0054] (3) The material preparation method and the application construction method are simple, the construction efficiency is high, and the cost is low, which is suitable for large-scale application. Description of the Drawings

[0055] Figure 1 It is the influence of the content of the skeleton material on the unconfined compressive strength of the fluidized solidified soil. Detailed Embodiments

[0056] The following embodiments more specifically describe the content disclosed in the present application. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the content disclosed in the present application are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the instruments used in the embodiments are all commercially available.

[0057] Example 1

[0058] The present embodiment provides a solid waste-based fluidized solidified soil, comprising a filling material, a skeleton material and a reinforcing material, wherein the filling material comprises the following components in parts by weight: 60 parts of foundation pit soil generated during construction of a construction project, calculated on a dry basis, 40 parts of alkali slag (industrial solid waste generated by the ammonia-alkali process for alkali production, whose main mineral components are CaCO3, CaSO4 and CaCl2), 1.5 parts of P·O42.5 cement, 3.5 parts of blast furnace slag, 10 parts of VAE emulsion, 3 parts of silica fume, 0.1 parts of hydroxypropyl methylcellulose, 0.1 parts of a composite water reducing agent (composed of 0.03 parts of polymethyl methacrylate-methacrylic acid copolymer and 0.07 parts of sodium hexametaphosphate), and 0.5 parts of NaOH;

[0059] The skeleton material is waste concrete blocks, with more mortar adhered to the blocks, and the size is 5mm~300mm;

[0060] The reinforcement material is discarded safety net.

[0061] The preparation and application construction method of fluidized solidified soil comprises the following steps:

[0062] (1) Foundation pit treatment: First, clean the bottom of the foundation pit, including loose soil, accumulated water, garbage, tree roots and other debris on the construction surface, then mark the height of the foundation pit backfill and measure the height, and then build the retaining wall according to the measured height. The retaining wall should be firm and sealed;

[0063] (2) Preparation of filling materials: First, soak the foundation pit soil in water to soften it, sieve it through a 50 mm pore size sieve, then add water and stir it thoroughly, and finally sieve it through a 5 mm pore size sieve to obtain a finished mud; the finished mud is then mixed with alkali residue, cement, blast furnace slag, VAE emulsion, silica fume, hydroxypropyl methylcellulose, compound water reducing agent, and NaOH to obtain the filling material;

[0064] (3) Fluidized solidified soil filling: Layered and segmented filling is adopted. Each layer is filled with filling materials first, and then with abandoned concrete blocks. The filling volumes of filling materials and abandoned concrete blocks are 80% and 20% respectively. Then, a vibrating rod is used to tamp and compact the abandoned concrete blocks to ensure that the abandoned concrete blocks are completely wrapped by the filling materials. The height of each layer of fluidized solidified soil filling shall not exceed 1000mm. After the top layer is filled, an abandoned safety net is laid, and pressure is applied to the abandoned safety net to make it immersed in the filling material.

[0065] (4) Maintenance: After the fluidized solidified soil is filled, it shall be covered with film for maintenance, and the maintenance time shall not be less than 7 days.

[0066] Example 2

[0067] The present embodiment provides a solid waste-based fluidized solidified soil, including a filling material, a skeleton material and a reinforcing material, wherein the filling material includes the following components in parts by weight: 95 parts of shield soil generated during construction of a construction project, calculated on a dry basis, 5 parts of calcium carbide slag (alkaline waste slag generated by hydrolysis of calcium carbide in the process of industrial production of polyvinyl chloride, the main mineral component of which is Ca(OH)2), 9 parts of P·O 42.5 cement, 9 parts of fly ash, 12 parts of blast furnace slag, 1 part of polyvinyl alcohol emulsion, 0.5 parts of silica fume, 1 part of methyl cellulose, 1 part of a composite water reducing agent (composed of 0.5 parts of polymethyl methacrylate-methacrylic acid copolymer and 0.5 parts of sodium hexametaphosphate), and 2 parts of Na2SiO3;

[0068] The skeleton material is waste brick blocks, with more mortar adhered to the blocks, and the size is 5mm~300mm;

[0069] The reinforcement material is fiber mesh cloth.

[0070] The preparation and application construction method of fluidized solidified soil comprises the following steps:

[0071] (1) Foundation pit treatment: First, clean the bottom of the foundation pit, including loose soil, accumulated water, garbage, tree roots and other debris on the construction surface, then mark the height of the foundation pit backfill and measure the height. Then, make a baffle according to the measured height. The baffle should be firm and sealed;

[0072] (2) Preparation of filling materials: First, fully soak the shield soil in water to soften it, sieve it through a 50 mm pore size sieve, then add water and stir it thoroughly, and finally sieve it through a 5 mm pore size sieve to obtain a finished mud; the finished mud is then mixed with carbide slag, cement, fly ash, blast furnace slag, polyvinyl alcohol emulsion, silica fume, methyl cellulose, compound water reducing agent, and Na2SiO3 to obtain the filling material;

[0073] (3) Fluidized solidified soil filling: Layered and segmented filling is adopted. Each layer is first filled with filling materials, and then with abandoned brick blocks. The filling volumes of filling materials and abandoned bricks are 40% and 60% respectively. Then, a vibrating rod is used to tamp and compact the abandoned brick blocks to ensure that the abandoned brick blocks are completely wrapped by the filling materials. The height of each layer of fluidized solidified soil filling shall not exceed 1000mm. After the top layer is filled, a fiber mesh cloth is laid and pressure is applied to the fiber mesh cloth to make it immersed in the filling material.

[0074] (4) Maintenance: After the fluidized solidified soil is filled, it shall be covered with film for maintenance, and the maintenance time shall not be less than 7 days.

[0075] Example 3

[0076] The present embodiment provides a solid waste-based fluidized solidified soil, including a filling material, a skeleton material and a reinforcing material, wherein the filling material includes the following components in parts by weight: 70 parts of foundation pit soil generated during construction of a construction project, calculated on a dry basis, 20 parts of alkali slag (industrial solid waste generated by the ammonia-alkali process for alkali production, with its main mineral components being CaCO3, CaSO4 and CaCl2), 10 parts of carbide slag (alkaline waste slag generated by the hydrolysis of carbide in the process of industrial production of polyvinyl chloride, with its main mineral component being Ca(OH)2), 3.6 parts of P·O42.5 cement, 8.4 parts of blast furnace slag, 5 parts of polyvinyl alcohol emulsion, 1 part of silica fume, 0.3 parts of methyl cellulose, 0.3 parts of a composite water reducer (including 0.1 parts of polymethyl methacrylate-methacrylic acid copolymer and 0.2 parts of sodium hexametaphosphate), and 0.5 parts of Na2SiO3;

[0077] The skeleton material is waste concrete blocks, with more mortar adhered to the blocks, and the size is 5mm~300mm;

[0078] The reinforcement material is discarded safety net.

[0079] The preparation and application construction method of fluidized solidified soil comprises the following steps:

[0080] (1) Foundation pit treatment: First, clean the bottom of the foundation pit, including loose soil, accumulated water, garbage, tree roots and other debris on the construction surface, then mark the height of the foundation pit backfill and measure the height, and then build the retaining wall according to the measured height. The retaining wall should be firm and sealed;

[0081] (2) Preparation of filling materials: First, soak the foundation pit soil in water to soften it, sieve it through a 50 mm mesh, add water and stir it thoroughly, and finally sieve it through a 5 mm mesh to obtain a finished mud; the finished mud is then mixed with alkali slag, carbide slag, cement, blast furnace slag, polyvinyl alcohol emulsion, silica fume, methyl cellulose, compound water reducing agent, and Na2SiO3 to obtain the filling material;

[0082] (3) Fluidized solidified soil filling: Layered and segmented filling is adopted. Each layer is filled with filling materials first, and then with abandoned concrete blocks. The filling volumes of filling materials and abandoned concrete blocks are 50% and 50% respectively. Then, a vibrating rod is used to tamp and compact the abandoned concrete blocks to ensure that the abandoned concrete blocks are completely wrapped by the filling materials. The height of each layer of fluidized solidified soil filling shall not exceed 1000mm. After the top layer is filled, an abandoned safety net is laid, and pressure is applied to the abandoned safety net to make it immersed in the filling material.

[0083] (4) Maintenance: After the fluidized solidified soil is filled, it shall be covered with film for maintenance, and the maintenance time shall not be less than 7 days.

[0084] Comparative Example 1

[0085] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that no waste concrete blocks are filled, that is, the flowing state solidified soil only includes filling materials and reinforcing materials.

[0086] Comparative Example 2

[0087] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that no waste safety nets are laid, that is, the flowing state solidified soil only includes filling materials and framework materials.

[0088] Comparative Example 3

[0089] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that no waste concrete blocks are filled and no waste safety nets are laid, that is, the flowing state solidified soil only includes filling materials.

[0090] Comparative Example 4

[0091] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that no VAE emulsion is added to the filling materials.

[0092] Comparative Example 5

[0093] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that natural boulders are used as the framework materials.

[0094] Comparative Example 6

[0095] The method of Example 1 is adopted to prepare and apply the flowing state solidified soil for construction, with the difference that no alkali residue is added to the filling materials.

[0096] The foundation pit backfill with a width of 1200 mm and a depth of 1000 mm is filled with the flowing state solidified soil prepared by Examples 1 - 3 and Comparative Examples 1 - 6. After filling, it is covered with a film and cured for 7 days. The apparent density of the finished slurry and filling materials, and the bleeding rate, permeability coefficient, and unconfined compressive strength of the flowing state solidified soil prepared in Examples 1 - 3 and Comparative Examples 1 - 6 are tested, and the shrinkage and cracking conditions of the flowing state solidified soil on the filling surface are observed and recorded. Among them, the apparent density is tested in accordance with the "Standard Test Methods for Basic Properties of Building Mortars" (JTG / T 70 - 2009); the bleeding rate is tested with reference to the "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunnels" (T / CECS 563 - 2018); the unconfined compressive strength is tested in accordance with the "Technical Standard for Filling with Premixed Flowing State Solidified Soil" (T / CECS 1037 - 2022); the permeability coefficient is tested by the variable - head permeability test in accordance with the "Highway Geotechnical Test Procedures" (JTG 3430 - 2020). The test results are shown in Table 1.

[0097]

[0098] As can be seen from Table 1, the permeability coefficients and unconfined compressive strengths of the fluidized solidified soil in Examples 1 to 3 all meet the requirements of the "Technical Standard for Filling with Premixed Fluidized Solidified Soil" (T / CECS 1037-2022), and it has the characteristics of low bleeding rate, small drying shrinkage, good anti-cracking and anti-seepage performance.

[0099] The good fluidity of the fluidized solidified soil enables rapid backfilling in narrow spaces. However, due to the high viscosity and strong water absorption capacity of construction waste soil, to meet the requirements of high fluidity, it is usually necessary to add much more water than that required for the hydration of the cementitious material. After the filling is completed, the excess water migrates upward, and serious bleeding phenomena are likely to occur on the filling surface; as the water continuously evaporates, large shrinkage occurs on the filling surface, and even serious cracking phenomena appear.

[0100] By comparing Example 1 with Comparative Example 1 and Comparative Example 5, it can be seen that the waste concrete blocks have high strength and water absorption rate, and can absorb the excess water in the fluidized solidified soil in the initial stage of filling, thus reducing the bleeding rate of the fluidized solidified soil; as the cementitious material continuously hydrates and the water evaporates, the waste concrete blocks can release the absorbed water, thus ensuring the full hydration of the cementitious material. Both the waste concrete blocks and the crushed stones can play a good skeleton role, which can improve the bearing capacity of the solidified soil and limit the drying shrinkage of the solidified soil. However, due to the high water absorption rate of the waste concrete, it can absorb or release the excess water in the system, playing a good water retention effect and internal curing role. Therefore, the fluidized solidified soil prepared with waste concrete blocks has lower bleeding rate and shrinkage rate, higher compressive strength, and better anti-cracking and anti-seepage performance.

[0101] By comparing Example 1 with Comparative Example 2, it can be seen that laying waste safety nets on the surface of the fluidized solidified soil can improve the anti-cracking performance of the surface of the fluidized solidified soil. After the filling of the fluidized solidified soil is completed, the excess water in the system is likely to migrate upward, resulting in the water content in the upper part of the fluidized solidified soil being higher than that in the bottom. Coupled with the fact that the water evaporation mainly starts from the upper surface, the drying shrinkage in the upper part of the fluidized solidified soil is much higher than that in the bottom. The uneven shrinkage is likely to generate large stress, thus causing cracking of the solidified soil. The waste safety nets can bear the shrinkage stress, reduce the generation of cracks, and hinder their expansion.

[0102] By comparing Example 1 with Comparative Example 3, it can be seen that the fluid-solidified soil prepared by combining filling materials, skeleton materials and reinforcing materials has the characteristics of low bleeding rate, high compressive strength, small dry shrinkage, excellent impermeability and anti-cracking performance. The waste concrete blocks and brick block skeleton materials of the present invention have a high water absorption rate. In the initial stage of filling, they can absorb the excess water in the fluid-solidified soil, thereby reducing the bleeding rate of the fluid-solidified soil. In the later stage, they can release the absorbed water, thus ensuring the full hydration of the cementitious materials and playing a good internal curing role. At the same time, the waste concrete blocks contain unhydrated cement particles and hydration products, and the waste brick blocks contain unhydrated cement particles, hydration products or calcined clay (sintered clay bricks), and they have certain hydration activity. Under the action of alkaline waste residues, they can also cross-link with clay minerals and cementitious material hydration products to form a stable three-dimensional network structure. In addition, the skeleton materials also have high strength, and when lapped together, they form the skeleton structure of the solidified soil, which improves the bearing capacity of the solidified soil while restricting the dry shrinkage of the solidified soil. Laying waste safety nets or fiber mesh cloth on the surface of the fluid-solidified soil can absorb the internal stress generated by the shrinkage of the solidified soil and effectively inhibit the generation and expansion of cracks. By constructing a skeleton structure in the filling materials and adding an anti-cracking protective layer to its surface, the problems of high bleeding rate, large dry shrinkage and easy cracking of the fluid-solidified soil are effectively solved, and its comprehensive performance and engineering backfill quality are improved.

[0103] By comparing Example 1 with Comparative Example 4, it can be seen that adding VAE emulsion significantly improves the impermeability of the fluid-solidified soil and also has a certain promoting effect on its compressive strength. The VAE emulsion and polyvinyl alcohol emulsion of the present invention have good filling and film-forming properties, can fill the pores of the solidified soil and cut off the connected pores, thereby improving its impermeability. At the same time, the VAE emulsion and polyvinyl alcohol emulsion have good bonding properties and can improve the bonding strength between raw materials. In addition, due to the hydrophilic groups in the VAE emulsion and polyvinyl alcohol emulsion, they are prone to cross-linking bonding reactions with Ca 2+ 、Na + 、[AlO4] 5- 、[SiO4] 4- during the polymerization process, forming an organic-inorganic composite interpenetrating network structure, making the hardened body structure exhibit more excellent macroscopic mechanical properties.

[0104] By comparing Example 1 with Comparative Example 6, it can be seen that adding alkali slag increases the compressive strength of the fluid-solidified soil. The alkali slag and carbide slag of the present invention can provide an alkaline environment and have an activating effect on the active components in clay minerals, cementitious materials, and skeleton materials (sintered clay bricks), etc., and can accelerate the dissolution and polymerization reactions of SiO4 and AlO4 tetrahedron The dissolved Ca 2+ 、Si 4+ 、Al 3+ 、Fe3+ High-valent cations such as can exchange ions with Na adsorbed on the surface of clay particles + , K + etc., reducing the thickness of the double electric layer on the surface of clay particles, increasing the force between clay particles, promoting the aggregation of clay particles into clusters, and being beneficial to improving the strength of the filling material; The cementitious substances such as C-A-S-H and N-A-S-H generated by the polymerization reaction have high strength and stability, which can improve the compressive strength and water stability of solidified soil. Under the action of alkaline waste residue, clay mineral components react with cementitious substances such as C-S-H, C-A-H, C-A-S-H, and N-A-S-H to form flaky, fibrous or needle-like crystals, increasing the connection between clay particles and cementitious substances and forming a stable coagulation network structure. Under the action of alkaline waste residue, the skeleton material can also crosslink with clay minerals and the hydration products of cementitious materials to form a stable three-dimensional network structure. By adding alkaline waste residue, the present invention stimulates the hydration activity of active components in clay minerals, cementitious materials, and skeleton materials (sintered clay bricks), etc., and provides sufficient calcium source, not only generating more coagulation substances, but also enhancing the connection between gel substances, muck particles, and skeleton materials, forming a stable three-dimensional network structure and improving the compressive strength of solidified soil.

[0105] To comparatively analyze the influence of the content of the skeleton material on the performance of fluidized solidified soil, Example 4 is provided.

[0106] Example 4

[0107] The fluidized solidified soil was prepared by the method of Example 3, except that: the size of the skeleton material was 5 mm to 25 mm, and the filling volumes were 0, 10%, 20%, 30%, 40%, 50%, 60%, and 70% respectively.

[0108] The fluidized solidified soil prepared in Example 4 was formed in a 150 mm×150 mm×150 mm test mold. Its unconfined compressive strength was tested in accordance with the "Technical Standard for the Filling of Premixed Fluidized Solidified Soil" (T / CECS 1037-2022), and the test results are as Figure 1 shown.

[0109] It can be seen from Figure 1 that as the content of waste concrete blocks increases, the compressive strength of the fluidized solidified soil at each age first increases and then decreases, and is higher than the compressive strength of the specimen without waste concrete blocks; when the content of waste concrete blocks is 50%, its compressive strength reaches the maximum value, and when its content is 70%, the phenomenon of waste concrete blocks being exposed appears, that is, the filling material is not enough to completely wrap the skeleton material.

[0110] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A solid waste-based fluid-solidified soil, characterized in that: It includes filling materials, skeleton materials and reinforcing materials; The filling materials include the following components in parts by weight: 60 - 95 parts of engineering muck, 5 - 40 parts of alkaline waste residue, 5 - 30 parts of cementitious material, 1 - 10 parts of polymer emulsion, 0.5 - 3 parts of silica fume, 0.1 - 1 part of cellulose ether, 0.1 - 1 part of compound water reducer, 0.5 - 2 parts of activator; The skeleton materials include waste concrete blocks and / or waste brick blocks; The reinforcing materials include waste safety nets and / or fiber mesh cloths.

2. The solid waste-based fluid-solidified soil according to claim 1, wherein: The filling materials include the following components in parts by weight: 65 - 85 parts of engineering muck, 15 - 35 parts of alkaline waste residue, 8 - 20 parts of cementitious material, 3 - 8 parts of polymer emulsion, 0.5 - 1.5 parts of silica fume, 0.1 - 0.5 part of cellulose ether, 0.1 - 0.5 part of compound water reducer, 0.5 - 1.5 parts of activator.

3. A kind of solid waste - based flowable solidified soil according to claim 1 or 2, characterized in that: The main components of the engineering muck include SiO2 and Al2O3; The alkaline waste residue includes alkali residue and / or carbide slag; The cementitious material includes at least one of cement, blast furnace slag, fly ash, steel slag, tungsten tailings, lithium slag, red mud; The polymer emulsion includes VAE emulsion and / or polyvinyl alcohol emulsion; The cellulose ether includes at least one of methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose; The compound water reducer includes polymethyl methacrylate - methacrylic acid copolymer and sodium salt; The activator includes at least one of NaOH, Na2SiO3, Na2SO4, Na2CO3.

4. A kind of solid waste - based flowable solidified soil according to claim 3, characterized in that: The engineering muck includes at least one of foundation pit soil, shield soil, slurry generated during construction engineering construction; The alkali residue is an industrial solid waste generated by the ammonia - soda method for making soda; The carbide slag is an alkaline waste residue generated by the hydrolysis of calcium carbide during the industrial production of polyvinyl chloride; The sodium salt includes at least one of sodium hexametaphosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium carbonate, sodium phosphate, sodium oxalate.

5. A kind of solid waste - based flowable solidified soil according to claim 3, characterized in that: The specific surface area of the alkali residue is not less than 300 m 2 / kg; The specific surface area of the carbide slag is not less than 300 m 2 / kg; The specific surface area of the blast furnace slag is not less than 400 m 2 / kg; The specific surface area of the fly ash is not less than 300 m 2 / kg; The specific surface area of the steel slag is not less than 400 m 2 / kg; The specific surface area of the tungsten tailings is not less than 400 m 2 / kg; The specific surface area of the lithium slag is not less than 400 m 2 / kg; The specific surface area of the red mud is not less than 300 m 2 / kg; The specific surface area of the silica fume is not less than 15 m 2 / g.

6. A solid waste-based fluid-solidified soil according to claim 1, characterized in that: The solid content of the polymer emulsion is not less than 50wt%.

7. A method for preparing solid waste-based fluidized solidified soil according to any one of claims 1 to 6, characterized in that: First, mix the engineering muck with water to obtain finished slurry; then mix the finished slurry with alkaline waste residue, cementitious material, polymer emulsion, silica fume, cellulose ether, compound water reducer and activator to obtain filling materials; then mix the filling materials with skeleton materials for filling and laying the reinforcing materials on the surface, thus obtaining.

8. The preparation method of a solid waste-based fluid-solidified soil according to claim 7, characterized in that: The filling materials and the skeleton materials are mixed and filled in multiple layers and then the reinforcing materials are laid on the surface.

9. A preparation method of a kind of solid waste - based flowable solidified soil according to claim 7, characterized in that: The size of the skeleton materials is 5mm - 300mm; The volume ratio of the skeleton materials is 20% - 60%.

10. The preparation method of a solid waste-based fluidized solidified soil according to claim 8, characterized in that: The single - layer filling height does not exceed 1000mm.

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