Solid waste low-carbon flow-state solidified soil dry-mixed curing agent as well as preparation method and application thereof

Abstract

The invention discloses a solid waste low-carbon flow-state solidified soil dry-mixed curing agent as well as a preparation method and application thereof, relates to a building material belonging to the field of solid waste recycling and geotechnical engineering materials, and aims to provide a solid waste low-carbon flow-state solidified soil dry-mixed curing agent which meets engineering requirements of fertilizer groove backfilling, cavity filling and the like, really realizes treatment of waste with waste, realizes resource utilization of low-carbon zero cement, and has a good application prospect. The curing agent has remarkable environmental benefits and engineering applicability. The solid waste low-carbon flow-state solidified soil dry mixing type curing agent is prepared from the following components in parts by weight: 30 to 45 parts of modified converter steel slag powder, 25 to 35 parts of activated municipal waste incineration bottom ash and 4 to 8 parts of acidified bentonite. The preparation method of the curing agent comprises the following steps: respectively preparing the three solid waste-based functional components, weighing according to the ratio, uniformly mixing with the solid dispersing agent in a closed mixer, bagging, sealing, and storing in a damp-proof manner. During construction, the curing agent is mixed with soft clay according to the mass ratio of 20%-35% of the dry weight of the on-site soft clay to form the flow-state solidified soil with the self-leveling performance, and the unconfined compressive strength within 28 days reaches 0.4-0.8 Mpa.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a dry-mix solidifying agent for low-carbon fluidized solidified soil from solid waste, its preparation method, and its application. Background Technology

[0002] With the rapid development of urban infrastructure construction in my country, underground space development is becoming increasingly frequent, leading to a continuous increase in demand for backfilling projects in narrow or irregularly shaped areas such as foundation pit support, trench backfilling, pipe gallery trenches, and bridge abutment backfilling. Traditional backfilling methods often involve manual layering and compaction of plain soil or graded sand and gravel, which suffers from prominent problems such as low construction efficiency, difficulty in controlling compaction, and susceptibility to post-construction settlement. These methods fail to meet the comprehensive requirements of modern engineering for efficient construction, long-term structural stability, and green construction. Against this backdrop, fluidized solidified soil, as a new type of environmentally friendly geotechnical engineering material with high fluidity, self-compacting properties, and controllable strength, has been widely used in municipal, transportation, and underground engineering projects in recent years.

[0003] Especially in coastal soft soil areas like Shanghai, construction waste typically exhibits characteristics of soft clay, such as high moisture content, low cohesion, and organic matter content. This type of soil has a loose structure, strong water retention, and weak cementing ability, placing higher demands on the adaptability of solidification materials. Existing fluidized bed solidification technologies mostly use ordinary silicate cement as the main solidifying agent. While the technology is mature, its high carbon emission characteristics seriously conflict with the "dual-carbon" strategy. Furthermore, it is prone to cracking due to drying shrinkage in high-moisture soft soil, resulting in poor volume stability. This makes it difficult to meet the comprehensive performance requirements of backfilling projects in Shanghai, which require low strength, low permeability, good fluidity, and controllable setting time.

[0004] To achieve a green and low-carbon transformation, alkali activation technology is considered an important alternative to traditional cement. Activation materials use strongly alkaline activators to activate silica- and aluminum-rich industrial solid wastes such as slag, steel slag, and fly ash, generating a cementitious product primarily composed of C-(A)-SH gel, which exhibits high strength, good impermeability, and excellent volume stability. More importantly, this technology enables the high-value utilization of large quantities of industrial solid waste, significantly reducing the carbon footprint and aligning with the concepts of circular economy and sustainable development. However, existing alkali-activated fluidized bed solidification technologies still have several shortcomings in adapting to the soft soil and clay of the coastal area of ​​Shanghai:

[0005] For example, excessive strength can lead to resource waste and structural incompatibility. The paper (Wang Hailong et al., "Research on the Preparation of Fluidized Solidified Soil from Alkali-Activated Mineral Powder and Its Engineering Application") describes the preparation of high-performance fluidized solidified soil using quicklime as an alkali activator and adding a small amount of anhydrite, achieving a 28-day strength of 9.59 MPa. However, this alkali-activated product far exceeds the actual requirement of 0.4-0.8 MPa for backfilling projects, and its excessive stiffness can easily cause deformation incompatibility with surrounding flexible structures, potentially increasing the risk of cracking.

[0006] Secondly, it has poor adaptability to soft clay with high water content and organic matter. For example, Chinese invention patent (CN118812204A) discloses an alkali-activated solid waste composite high-fluidity solidified silt and its preparation method, including the following raw materials: 8-15 parts alkali-activated solid waste solidifying agent, 72-85 parts excavated silt, and 7-13 parts added water. The alkali-activated solid waste solidifying agent is composed of solid waste (such as fly ash, waste glass powder, slag, etc.), cement, alkali activator (low-modulus water glass solution), and additives (dispersant, expanding agent, nanomaterials) in a mass ratio of 50:30:5:15. This patented technical solution achieves the resource utilization of engineering waste soil and industrial solid waste, improves the fluidity and early strength of fluidized solidified soil, shortens the setting time, and has good application prospects in fields such as foundation pit backfilling and road base filling. However, this technical solution can only prepare fluidized solidified soil from silt. When the soil material is soft clay with high water content and organic matter, the high water content slurry will settle during the static process due to the density difference between soil particles and solidified components, resulting in a stratification phenomenon with a loose upper structure and a dense lower layer. This leads to uneven distribution of the solidified body strength along the depth direction. On the other hand, organic matter in the soil will interfere with the alkali-activated reaction, inhibit the generation of hydration products, and further weaken the development of overall strength.

[0007] Moreover, existing technologies have failed to truly achieve synergistic optimization of cost, low carbon footprint, and performance. For example, Chinese invention patent (CN118930165A) discloses an alkali-activated dispersion curing agent based on clay geology and its preparation method. In this technical solution, the curing agent raw materials, by mass parts, include: 90-92 parts of ordinary silicate cement, 0.5-1 parts of rapid penetrant, 3-5 parts of organically modified calcium carbonate, 0.05-0.1 parts of sodium silicate, and 0.03-0.05 parts of sodium hexametaphosphate. By mixing the above components evenly with clay at a mass ratio of 1:10 and stirring for 15 minutes, effective curing of the clay can be achieved, improving its strength, durability, and stability, which has certain application value in fields such as foundation pit support and foundation treatment. However, the precursor is highly dependent on cement, and the core cementing material of the technical solution is still ordinary silicate cement. The overall system is still a typical cement-dominated system. Even though the patent emphasizes "low energy consumption and environmental protection," since the cement accounts for more than 90%, it cannot reflect the advantages of green and low carbon footprint. Although sodium silicate and sodium hexametaphosphate were introduced as alkali-activating components, their dosage was extremely low, serving only as auxiliary activation agents. They could not form an independent alkali-activating network, resulting in limited activation effects and relying solely on the cement-dominated reaction mechanism. Essentially, it still follows a traditional high-carbon pathway and cannot solve the dual challenges of greening and adaptability for soft soil backfilling in Shanghai.

[0008] In summary, there is an urgent need to develop a dry-mix solidification agent for low-carbon fluidized solidified soil specifically designed for soft clay with high moisture content and organic matter. This agent should precisely match engineering performance indicators such as low strength, high fluidity, and low permeability, completely eliminating the need for cement and high-carbon activators, safely utilizing industrial solid waste such as steel slag, and effectively suppressing stratification and organic matter interference. This would provide an economical, environmentally friendly, and reliable backfilling solution for urban underground engineering. Summary of the Invention

[0009] To address the technical challenges of solidifying high-organic-matter, high-moisture-content soft clay in backfilling projects, such as slow strength development and organic matter inhibiting hydration, this invention provides a solid waste-based, zero-liquid-alkali activator, low-carbon dry-mix fluidized solidification soil solidifier.

[0010] One of the technical solutions provided by this invention is a dry-mix solidifying agent for low-carbon fluidized solidified soil of solid waste, comprising the following components in parts by weight:

[0011] 30-45 parts of modified converter steel slag powder

[0012] Activate 25-35 parts of bottom ash from municipal solid waste incineration.

[0013] 4-8 parts of acidified bentonite.

[0014] The present invention relates to a dry-mix solidifying agent for low-carbon fluidized solidified soil in solid waste, wherein the main original chemical composition of the modified converter steel slag powder, by mass fraction, includes: CaO 40-55%, SiO2 10-15%, Fe2O3 15-25%, MgO 5-8%, Al2O3 3-5%, and the free CaO content is 1.5-3.5%.

[0015] This invention relates to a dry-mix solidifier for low-carbon fluidized solidified soil from solid waste. The modified converter steel slag powder is prepared through a three-step process: pre-carbonization, micropore construction, and oxidant confined loading. Specifically, the process includes the following steps:

[0016] S1. Mix converter steel slag powder with water, adjust the water-to-solid ratio to 0.10-0.15, and form a uniform wet powder;

[0017] S2. The wet powder is placed in a CO2 atmosphere of 0.1-0.2 MPa and carbonized at room temperature for 24-48 hours to convert free CaO and MgO into CaCO3 and MgCO3. Due to the volume expansion and phase change caused by the formation of carbonates, interconnected micropores and microcracks are formed in situ inside the particles.

[0018] S3. After drying the carbonized product, mix it with an aqueous solution containing sodium percarbonate (2Na2CO3·3H2O2) and potassium permanganate (KMnO4), wherein the total mass of the oxidant is 0.8-1.2% of the mass of the steel slag powder, and the mass ratio of sodium percarbonate to potassium permanganate is 3:1 to 5:1. Then dry it at 60-80℃ to allow the oxidant to be adsorbed and confined within the micropores; then grind the resulting product to a specific surface area greater than or equal to 450 m². 2 / kg, thus obtaining modified converter steel slag powder.

[0019] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, wherein the main original chemical composition of the activated municipal solid waste incineration bottom ash, by mass fraction, includes: SiO2 45-50%, CaO 20-25%, Al2O3 6-9%, Fe2O3 4-6%, MgO 1-3%, Na2O 5-7%.

[0020] This invention relates to a dry-mix solid waste low-carbon fluidized solidification soil solidification agent, wherein the activated municipal solid waste incineration bottom ash is obtained through hydrothermal co-activation of calcium carbide slag, specifically including the following steps:

[0021] B1. Crush and screen the raw ash from municipal solid waste incineration, and take the portion with a particle size less than 0.15mm;

[0022] B2. Wash the sieved material with deionized water 3-5 times, each time with a solid-liquid ratio of 1:5, and then filter.

[0023] B3. Mix the filtered bottom ash obtained in step B2 with carbide slag powder (Ca(OH)2≥75%) at a mass ratio of 100:(8-12), add water to adjust the slurry to a water-solid ratio of 0.20-0.25, and cure at 80-95℃ for 6-12 hours.

[0024] B4. Dry the curing product at 80-105℃ for 4-8 hours, and grind it until the specific surface area is greater than or equal to 350m². 2 / kg, which yields activated municipal solid waste incineration bottom ash.

[0025] The present invention relates to a dry-mix solidifying agent for low-carbon fluidized solidified soil in solid waste, wherein the main original chemical composition of the acidified bentonite, by mass fraction, includes: SiO2 70-75%, CaO 1-3%, MgO 1-3%, Fe2O3 1-3%, Al2O3 10-15%, K2O 1-3%, and Na2O 2-4%.

[0026] This invention relates to a dry-mix solidifier for low-carbon fluidized solidified soil from solid waste, wherein the acidified bentonite is prepared by room-temperature modification with acetic acid, specifically comprising the following steps:

[0027] C1. Crush and sieve the natural bentonite, and take the portion of bentonite with a particle size of less than or equal to 100μm;

[0028] C2. Mix the bentonite obtained in step C1 with a 0.5-2.0 mol / L acetic acid solution at a solid-liquid ratio of 1:5, and stir the mixture at 25-40℃ for 1-2 hours.

[0029] C3. Filter the reaction product, wash it with water until pH≈6-7, dry it at 80-105℃, and grind it until the specific surface area is greater than or equal to 200m² / kg to obtain acidified bentonite.

[0030] The resulting acidified bentonite can form a controllable swelling gel after mixing and contact with water, which can slow down the early hydration rate and effectively inhibit the bleeding and settling of soft clay with high water content.

[0031] Another technical solution provided by this invention is a method for preparing a dry-mix solidifying agent for low-carbon fluidized solidified soil of solid waste, comprising the following steps:

[0032] D1. Prepare modified converter steel slag powder, activated municipal solid waste incineration bottom ash, and acidified bentonite respectively;

[0033] D2. By weight: 30-45 parts modified converter steel slag powder, 25-35 parts activated municipal solid waste incineration bottom ash, 4-8 parts acidified bentonite. Weigh each component and add 1.0-2.6 parts of a solid dispersant composed of sodium methacrylate, polyethylene glycol monomethyl ether methacrylate and sodium 2-acrylamide-2-methylpropanesulfonate. Dry mix in a closed mixer for 10-20 minutes.

[0034] D3. After mixing, the materials are bagged and sealed for moisture protection and storage to obtain the dry-mix curing agent product.

[0035] The present invention relates to a method for preparing a dry-mix solidifying agent for low-carbon fluidized solidified soil in solid waste, wherein the mass ratio of sodium methacrylate, polyethylene glycol monomethyl ether methacrylate and sodium 2-acrylamide-2-methylpropanesulfonate in the solid dispersant is (1-3):(4-6):(1-2).

[0036] Another technical solution provided by this invention is the application of a dry-mix solid waste low-carbon fluidized solidified soil solidifier in soft clay solidification and backfilling projects, including backfilling of trenches in municipal engineering, filling of underground cavities, or roadbed reinforcement. During construction, the dry-mix solid waste low-carbon fluidized solidified soil solidifier is a completely dry-mixed powder. It is mixed with the soft clay at a mass ratio of 20-35% of the dry weight of the soft clay on site, and water is added and stirred to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 ±20kg / m 3This forms a fluidized solidified soil with self-leveling properties. Under standard curing conditions, its unconfined compressive strength reaches 0.4-0.8 MPa after 28 days, meeting the requirements of low-strength projects such as trench backfilling, underground cavity filling, or roadbed reinforcement.

[0037] This invention relates to the application of a dry-mix solid waste low-carbon fluidized solidified soil solidifier in soft clay solidification backfilling projects. The mixing is carried out using a forced mixer. First, the dry-mix solid waste low-carbon fluidized solidified soil solidifier is premixed with the dry soft clay material for no less than 1 minute. Then, water is added and the mixing continues for no less than 2 minutes. The total mixing time is no less than 3 minutes until the mixture is in a uniform fluid state and there is no obvious particle agglomeration.

[0038] The dry-mix solidifier for low-carbon fluidized solidified soil of solid waste and its application in this invention differ from existing technologies in that this invention has the following technical effects:

[0039] (1) This invention performs a three-step treatment on converter steel slag powder: "pre-carbonization - micropore construction - oxidant confined loading". This process enables the in-situ formation of interconnected micropores and microcracks within the steel slag particles, and stably adsorbs the compound oxidant of sodium percarbonate and potassium permanganate into the micropores. After being mixed with high-organic soft clay and exposed to water, the oxidant can slowly release H2O2 and MnO. 4- It specifically degrades humic acid-based phenolic hydroxyl organic matter and lignin and other high-molecular-weight, difficult-to-degrade components, effectively relieving the encapsulation and inhibition effect of organic matter on cementitious particles, and significantly improving the hydration reaction efficiency in soft soil systems with high water content and high liquid limit.

[0040] (2) This invention effectively activates the glass phase depolymerization in the bottom ash of municipal solid waste incineration through the synergistic activation of carbide slag and municipal solid waste incineration under humid and hot conditions, significantly enhancing the reactivity of SiO2 and Al2O3, and generating in situ an alkali-activated precursor rich in aluminosilicate oligomers and soluble alkali metal ions; after the precursor is mixed with soft clay and exposed to water, it can rapidly react with the Ca released from the modified steel slag. 2 + Synergistic reaction rapidly forms CASH gel and zeolite-like phase, achieving effective development of early strength; at the same time, the residual Ca(OH)2 in the activated base ash continuously provides an alkaline environment, maintaining the pH stability of the system, eliminating the need for external liquid alkali activators, and realizing a low-carbon curing process of all dry mixing, zero cement, and zero nanomaterials, significantly reducing carbon emissions and construction complexity.

[0041] (3) The present invention uses acetic acid to modify bentonite at room temperature. By controlling its interlayer spacing and surface charge, a controllable swelling gel network is formed after mixing and contact with water. This not only effectively inhibits the bleeding and particle sedimentation of soft clay systems with high water content, but also moderately adsorbs some of the free water in the in-situ soil, reduces the local water-solid ratio, accelerates the alkali-activated reaction and promotes the densification of CASH gel, which is beneficial to the early strength development.

[0042] (4) This invention introduces a solid dispersant composed of sodium methacrylate, polyethylene glycol monomethyl ether methacrylate and sodium 2-acrylamide-2-methylpropanesulfonate. Through the electrostatic repulsion of anionic groups, the steric hindrance effect of polyether side chains and the strong water retention capacity of sulfonic acid groups, multiple synergistic effects are achieved, which significantly improves the flow stability, self-leveling and filling density of the mixture. At the same time, all component modification and curing agent preparation processes are completed at room temperature or low temperature, without the need for high-temperature calcination or strong alkali treatment, which significantly reduces energy consumption and carbon emissions, and conforms to the green building materials development concept of "all solid waste, all dry mixing, and ultra-low carbon". Detailed Implementation

[0043] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0044] The raw materials used in the various embodiments of this invention are as follows:

[0045] (1) Converter steel slag powder: taken from a steel plant, with a chemical composition of CaO 48.2%, SiO2 12.5%, Fe2O3 18.7%, MgO 6.3%, Al2O3 4.1%, free CaO content 2.3%, specific surface area 420m² / kg, and particle size less than or equal to 80μm;

[0046] (2) Municipal solid waste incineration bottom ash: taken from an incineration plant in Shanghai, with the following chemical composition: SiO2 47.2%, CaO 22.5%, Al2O3 7.8%, Fe2O3 5.1%, MgO 1.9%, Na2O 6.3%, K2O 1.5%, SO3 2.1%, TiO2 0.7%;

[0047] (3) Calcium carbide slag powder: an industrial by-product, with a Ca(OH)2 content of 78.5% and a particle size of less than or equal to 80 μm;

[0048] (4) Natural bentonite: sodium-based bentonite with montmorillonite content greater than or equal to 85% and particle size less than or equal to 100 μm;

[0049] (5) Sodium percarbonate: industrial grade, with an effective active oxygen content of ≥13%;

[0050] (6) Potassium permanganate: Industrial grade, purity greater than or equal to 98%;

[0051] (7) Acetic acid: analytical grade, concentration 99.5%;

[0052] (8) Raw materials for solid dispersants: sodium methacrylate, polyethylene glycol monomethyl ether methacrylate, and sodium 2-acrylamide-2-methylpropanesulfonate, all of which are industrial grade;

[0053] (9) High organic matter soft clay: taken from a foundation pit at a construction site in Shanghai, with a liquid limit of 46.2%, a plastic limit of 24.1%, a natural moisture content of 45.8%, and an organic matter content of 4.6%;

[0054] (10) Mixing water: ordinary tap water.

[0055] The modified converter steel slag powder used in the various embodiments and comparative examples of this invention is prepared through the following steps:

[0056] By weight, 100 parts of converter steel slag powder were mixed with water, the water-to-solid ratio was adjusted to 0.12, and the mixture was stirred for 5 minutes to form a uniform wet powder. The wet powder was placed in a CO2 atmosphere at 0.15 MPa and carbonized at room temperature for 36 hours to convert free CaO / MgO into CaCO3 / MgCO3 and form a microporous structure in situ. After the carbonization product was dried at 80°C, it was mixed with an aqueous solution containing 1.0 part of sodium percarbonate and 0.25 parts of potassium permanganate, with a water-to-solid ratio of 0.1. The mixture was stirred for 10 minutes, then dried at 70°C and ground to a specific surface area of ​​450 m² / kg.

[0057] The activated municipal solid waste incineration bottom ash used in the various embodiments and comparative examples of this invention is prepared through the following steps:

[0058] Mix 100 parts of municipal solid waste incineration bottom ash with 10 parts of calcium carbide slag powder, add water to adjust the slurry to a water-to-solid ratio of 0.22, and cure at 90℃ for 8 hours under humid heat; dry the product at 95℃ for 6 hours and grind it to a specific surface area of ​​360m² / kg.

[0059] The acidified bentonite used in the various embodiments and comparative examples of this invention was prepared through the following steps:

[0060] 100 parts of bentonite were mixed with 1.0 mol / L acetic acid solution at a solid-liquid ratio of 1:5 and stirred at 30℃ for 1.5 h. After filtration, the mixture was washed with water until pH≈6.5, dried at 90℃, and ground until the specific surface area was 210 m² / kg.

[0061] In the solid dispersants of the various embodiments and comparative examples of the present invention, the mass ratio of sodium methacrylate, polyethylene glycol monomethyl ether methacrylate and sodium 2-acrylamide-2-methylpropanesulfonate is 2:5:2.

[0062] The dry-mix curing agents used in the embodiments and comparative examples of this invention are prepared through the following steps:

[0063] Weigh out the steel slag powder, bottom ash, and bentonite according to different mass ratios, then add 2.0 parts of solid dispersant, dry mix in a closed mixer for 15 minutes, then bag and seal for moisture protection.

[0064] Example 1

[0065] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 30 parts modified converter steel slag powder, 35 parts activated municipal solid waste incineration bottom ash, and 4 parts acidified bentonite.

[0066] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 35% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0067] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0068] Example 2

[0069] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 45 parts modified converter steel slag powder, 25 parts activated municipal solid waste incineration bottom ash, and 8 parts acidified bentonite.

[0070] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 20% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0071] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0072] Example 3

[0073] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 40 parts modified converter steel slag powder, 30 parts activated municipal solid waste incineration bottom ash, and 6 parts acidified bentonite.

[0074] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 30% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0075] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0076] Comparative Example 1

[0077] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 40 parts of converter steel slag powder, 30 parts of activated municipal solid waste incineration bottom ash, and 6 parts of acidified bentonite.

[0078] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 30% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0079] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0080] Comparative Example 2

[0081] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 40 parts modified converter steel slag powder, 30 parts municipal solid waste incineration bottom ash, and 6 parts acidified bentonite.

[0082] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 30% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0083] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0084] Comparative Example 3

[0085] The present invention relates to a dry-mix solidification agent for low-carbon fluidized solidified soil in solid waste, comprising the following components in parts by weight: 40 parts modified converter steel slag powder, 30 parts activated municipal solid waste incineration bottom ash, and 6 parts bentonite.

[0086] When using the dry-mix solidification agent for low-carbon fluidized solidified soil, mix it with the soft clay at a mass ratio of 30% of the dry weight of the high-organic-matter soft clay, add water and stir to adjust the wet bulk density of the resulting mixture to 1650 kg / m³. 3 .

[0087] The mixture is stirred using a forced mixer. First, the dry-mix curing agent and the dry soft clay are premixed for 1 minute, then water is added and the mixture is stirred for another 2 minutes until the mixture is uniformly fluid and free of obvious particle agglomeration.

[0088] According to the national standard GB / T 50123-2019 "Standard for Geotechnical Testing Methods", three parallel specimens were subjected to unconfined compressive strength testing at 28 days with a loading rate of 1 mm / min. The compressive strength was taken as the average value of the three specimens. The fluidity was tested according to DBJ51 / T188-2022 "Technical Standard for Premixed Flowable Solidified Soil Filling Engineering". The organic matter content was tested according to the loss on ignition method in the industry standard JTG 430-2020 "Specifications for Highway Geotechnical Testing".

[0089] Table 1 Results of solidified soil performance tests

[0090] Group 28-day strength (MPa) Liquidity (mm) Organic matter content (%) Does it bleed / sediment? Example 1 0.59 190 1.3 no Example 2 0.68 180 1.1 no Example 3 0.63 185 1.4 no Comparative Example 1 0.36 180 3.7 yes Comparative Example 2 0.25 175 3.4 yes Comparative Example 3 0.33 165 2.9 yes

[0091] As can be seen from Examples 1-3, the dry-mix curing agent provided by this invention, when mixed with soft clay at a mass ratio of 20-35% of the dry weight of high-organic-matter soft clay and with the wet bulk density adjusted to 1650 kg / m³, achieves the desired effect. 3 Under the given conditions, fluidized solidified soil with excellent comprehensive performance can be prepared: the 28-day unconfined compressive strength is stable at 0.59-0.68 MPa, the fluidity reaches 180-190 mm, the organic matter content is significantly reduced to 1.1-1.4%, and there is no bleeding or settling. This indicates that the present invention, through a three-in-one technical approach of "modified steel slag oxidative degradation of organic matter - activation of bottom ash to construct alkali activation network - acidification of bentonite to stabilize flow and suppress sedimentation," has successfully achieved efficient adaptation to soft clay with high water content and high organic matter. Under the premise of completely eliminating the use of cement and liquid alkali activators, it accurately meets the backfilling strength requirements of 0.4-0.8 MPa, and has the advantages of low carbon content, stability, and construction applicability.

[0092] Combining Example 3 and Comparative Example 1, it can be seen that the curing agent prepared from converter steel slag powder modified in three steps—pre-carbonization, microporous construction, and oxidant confined loading—as described in this invention, compared to using unmodified ordinary converter steel slag powder, resulted in a 28-day strength of the prepared fluidized solidified soil that increased from 0.36 MPa to 0.63 MPa, and an organic matter content that decreased from 3.7% to 1.4%, while completely eliminating bleeding and settling phenomena. This indicates that the directional modification of steel slag in this invention not only effectively degrades organic inhibitors such as humic acid and lignin in soft clay, removing their encapsulation effect on the cementation reaction, but also significantly improves the hydration activity and volume stability of the system through carbonization conversion of free CaO / MgO into stable carbonates.

[0093] Combining Example 3 and Comparative Example 2, it can be seen that the solidifying agent prepared from municipal solid waste incineration bottom ash through hydrothermal synergistic activation with carbide slag as described in this invention significantly increases the 28-day strength of the prepared fluidized solidified soil from 0.25 MPa to 0.63 MPa compared to using unactivated original bottom ash, with a 10 mm increase in fluidity and more thorough degradation of organic matter. This indicates that carbide slag effectively stimulates the depolymerization of the glassy silica-alumina phase in the bottom ash under hydrothermal conditions, generating in-situ silica-alumina-rich gel and soluble alkali metal ions, constructing a highly efficient alkali-activated precursor; this precursor, along with the Ca released from modified steel slag... 2+ Synergistically forming CASH gel, achieving efficient gelation without the addition of external liquid alkali activators, significantly improving strength and reaction efficiency.

[0094] Combining Example 3 and Comparative Example 3, it can be seen that the curing agent prepared using the acetic acid-modified acidified bentonite described in this invention, compared with the use of unacidified natural bentonite, increases the 28-day strength of the prepared fluidized solidified soil from 0.33 MPa to 0.63 MPa, improves fluidity by 20 mm, and completely inhibits bleeding and particle sedimentation. This indicates that acetic acid modification effectively regulates the interlayer structure and swelling behavior of bentonite, enabling it to form a uniform and controllable gel network in a high-water-content system. This network can stabilize suspended particles, prevent stratification, and moderately adsorb free water to reduce the local water-to-solid ratio, promoting densification through alkali-activated reaction, thereby synergistically improving fluidity, uniformity, and mechanical properties.

[0095] By pre-carbonizing to construct a microporous structure within the converter steel slag and confining it with a compound oxidant of sodium percarbonate and potassium permanganate, the system can in situ and synergistically degrade humic acid and lignin in the soft clay during mixing, effectively relieving their inhibitory effect on hydration reactions. Simultaneously, the activity of the municipal solid waste incineration bottom ash is significantly enhanced after wet-heat activation with carbide slag, forming a cementitious network in synergy with the steel slag. Acidified bentonite forms a controllable swelling gel in the high-moisture system, effectively inhibiting bleeding and sedimentation and ensuring flow stability. The entire system requires no liquid alkali activator and is cement-free, achieving fully dry mixing, low carbon, and high solid waste synergy, precisely adapting to the low-strength backfilling requirements of high-moisture, high-organic-matter soft clay.

[0096] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A solid waste low-carbon flow state solidified soil dry-mix type solidifying agent, characterized in that: By weight parts, including the following components: Modified converter steel slag powder 30-45 parts, Activated municipal solid waste incineration bottom ash 25-35 parts, Acidification bentonite 4-8 parts.

2. The solid waste low-carbon fluidified soil curing agent of dry-mixed type according to claim 1, characterized in that: The modified converter steel slag powder includes CaO 40-55%, SiO2 10-15%, Fe2O3 15-25%, MgO 5-8%, Al2O3 3-5% and free CaO 1.5-3.5% by mass fraction; the preparation method of the modified converter steel slag powder includes the following steps: Step S1, mixing converter steel slag powder with water, adjusting the water-solid ratio to 0.10-0.15 to form a uniform wet powder; Step S2, placing the wet powder in a CO2 atmosphere of 0.1-0.2Mpa, carbonizing at room temperature for 24-48h, converting free CaO and MgO into CaCO3 and MgCO3, and forming a connected microporous and microfracture structure in situ in the particle interior due to the volume expansion and phase change caused by the generation of carbonates; Step S3, after drying the carbonization product in step S2, mix with an aqueous solution containing sodium percarbonate and potassium permanganate, wherein the total mass of oxidizing agent is 0.8-1.2% of the mass of the steel slag powder, and the mass ratio of sodium percarbonate to potassium permanganate is 3:1 to 5:1; then dry at 60-80°C, so that the oxidizing agent is adsorbed and confined in the micropores; then grind the resulting product to a specific surface area greater than or equal to 450 m 2 / kg, to obtain modified converter steel slag powder.

3. The solid waste low-carbon fluidified soil curing agent of dry-mixed type according to claim 1, characterized in that: The activated municipal solid waste incineration bottom ash includes SiO2 45-50%, CaO 20-25%, Al2O3 6-9%, Fe2O3 4-6%, MgO 1-3% and Na2O 5-70% by mass fraction; the preparation method of the activated municipal solid waste incineration bottom ash includes the following steps: Step B1, crushing and sieving the municipal solid waste incineration bottom ash raw ash, and taking the part with a particle size less than 0.15mm; Step B2, washing the undersize material with water for 3-5 times, with a solid-liquid ratio of 1:5 each time, and filtering after washing; Step B3, mixing the filtered bottom ash obtained in step B2 with carbide slag powder at a mass ratio of 100:(8-12), adding water to adjust the water-solid ratio to 0.20-0.25, and wet heat curing at 80-95℃ for 6-12h; Step B4, dry the maintenance product at 80-105℃ for 4-8h, grind to specific surface area greater than or equal to 350m 2 / kg, to obtain the activated municipal solid waste incineration bottom ash.

4. The solid waste low-carbon fluidified soil curing agent of dry-mixed type according to claim 1, characterized in that: The acidification bentonite includes SiO2 70-75%, CaO 1-3%, MgO 1-3%, Fe2O3 1-3%, Al2O3 10-15%, K2O 1-3% and Na2O 2-4% by mass fraction; the preparation method of the acidification bentonite includes the following steps: Step C1, crushing and sieving the bentonite, and taking the part with a particle size less than or equal to 100μm; Step C2, mixing the bentonite obtained in step C1 with a 0.5-2.0mol / L acetic acid solution at a solid-liquid ratio of 1:5, and stirring at 25-40℃ for 1-2h; Step C3. The reaction product is suction filtered, washed with water until pH ~ 6-7, dried at 80-105°C, ground to a specific surface area greater than or equal to 200 m2 / kg, and calcined at 600-800°C, obtaining the acid bentonite. 2 / kg, obtaining the acid bentonite.

5. A method for preparing the dry-mix type solidification agent for solid waste low-carbon fluidized soil solidification according to any one of claims 1-4, characterized in that: Including the following steps: Step D1, respectively preparing the modified converter steel slag powder, the activated municipal solid waste incineration bottom ash and the acidification bentonite; Step D2, taking each component by weight parts according to claim 1, and then adding 1.0-2.6 parts of a solid dispersing agent, and dry mixing in a closed mixer for 10-20min; Step D3, after mixing, the material is packed and sealed to prevent moisture, and stored, to obtain a dry-mixed type curing agent finished product.

6. The method of claim 5, wherein: The solid dispersing agent includes sodium methacrylate, polyethylene glycol monomethyl ether methacrylate and 2-acrylamide-2-methylpropanesulfonic acid sodium, and the mass ratio of the above components is (1-3):(4-6):(1-2).

7. The use of a dry-mix type solidification agent for solid waste low-carbon fluidized solidified soil according to any one of claims 1-4, characterized in that: Including municipal engineering fat groove backfill, underground cavity filling or roadbed reinforcement.

8. Use according to claim 7, characterized in that: The municipal engineering fat groove backfill, underground cavity filling or roadbed reinforcement construction, the solid waste low carbon flow state solidified soil dry mixed type solidified agent is mixed with the soft clay according to the mass ratio of 20-35% of the dry weight of the soft clay, and water is added and stirred, the wet bulk density of the obtained mixture is adjusted to 1650kg / m 3 ±20kg / m 3 , the flow state solidified soil with self-leveling performance is formed, and the unconfined compressive strength of the flow state solidified soil under standard curing conditions for 28 days reaches 0.4-0.8MPa.

9. Use according to claim 8, characterized in that: The mixing is performed by a compulsory mixer, the dry-mixed curing agent is premixed with the soft clay dry material for not less than 1 minute, then water is added and continues to be mixed for not less than 2 minutes, the total mixing time is not less than 3 minutes, until the mixture is uniform and has no obvious particle agglomeration.