Adjustable composite curing agent for fluid stabilized soil as well as preparation method and application of composite curing agent

Abstract

The invention discloses an adjustable composite curing agent for fluid stabilized soil as well as a preparation method and application thereof, and belongs to the technical field of civil engineering materials. The technical scheme adopted by the invention is as follows: the adjustable composite curing agent for the flow-state cured soil comprises the following components in percentage by weight: 50-70% of a gel base material, 10-20% of a curing agent, 1-5% of a curing agent and 1-5% of a curing agent, 8-12% of an exciting agent; 5-8% of a function regulator; 15-25% of a filling material; wherein the gelling base material comprises 15-25% of ordinary Portland cement, 10-20% of steel slag micro powder, 10-15% of fly ash and 5-10% of coal gangue powder; the exciting agent comprises 4-6% of desulfurized gypsum, 2-4% of silica fume and 2-3% of sodium carbonate; by optimizing the ratio of the gelling base material, the excitant, the function regulator and the filler and combining with a specific raw material pretreatment process, the working performance of the flow-state solidified soil is ensured, meanwhile, the strength is precisely regulated and controlled, and the flow-state solidified soil has the advantages of being low in cost, high in solid waste utilization rate, adjustable in performance and capable of meeting municipal engineering requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering materials, and particularly relates to an adjustable composite curing agent for fluidized solidified soil, a preparation method and an application thereof. Background Art

[0002] As an engineering material with high fluidity and low strength, fluidized soil is widely used in municipal engineering, particularly in trench backfill and roadbed cushioning. However, conventional fluidized soil curing agents face numerous challenges in practical application, hindering their further promotion and development.

[0003] Existing technologies have significant flaws in curing agent formulation design. Some technologies rely on high cement dosages or complex formulations, resulting in high material costs. For example, some curing agents rely on sulfoaluminate cement, which is expensive and significantly increases project costs. Furthermore, existing technologies generally have low utilization rates for industrial solid waste, failing to fully utilize low-cost solid wastes such as fly ash and coal gangue. This not only wastes resources but also violates environmental protection policies.

[0004] In terms of performance, existing technologies suffer from serious performance redundancy issues. Most technical solutions excessively pursue high strength, but fluidized solidified soil in municipal engineering typically only requires a lower strength range. High strength targets lead to significant material waste and violate the principle of economy. Furthermore, traditional curing agents lack flexibility in performance control, making it difficult to dynamically adjust to the strength and economic requirements of different projects. This makes it difficult to precisely adapt curing agents to the diverse application scenarios in municipal engineering, limiting the scope of application of fluidized solidified soil.

[0005] Existing curing agents also suffer from irrational component ratios, making it difficult to achieve cost optimization while maintaining performance. In particular, imprecise control over the ratios of the gelling base, activator, functional modifier, and filler leads to unstable material properties or excessive costs. Furthermore, existing technologies lack robust raw material pretreatment processes, impacting the performance stability of the final product. Summary of the Invention

[0006] The present invention provides an adjustable composite curing agent for fluidized soil curing, and a preparation method and application thereof, to solve at least one of the above technical problems.

[0007] The technical solution adopted in the present invention is:

[0008] An adjustable fluidized soil solidification composite solidifying agent, comprising the following components by weight percentage:

[0009] Cementitious base material: 50-70%; activator: 8-12%; functional regulator: 5-8%; filler: 15-25%; wherein, the cementitious base material includes 15-25% of ordinary Portland cement, 10-20% of steel slag powder, 10-15% of fly ash, and 5-10% of coal gangue powder; the activator includes 4-6% of desulfurized gypsum, 2-4% of silica fume, and 2-3% of sodium carbonate; the functional regulator includes 1-2% of lignin sulfonate water reducer, 0.5-1% of sucrose retarder, and 0.5-1% of sodium sulfate early strength agent; the filler includes 10-15% of recycled construction waste powder and 5-10% of river sand fine powder.

[0010] Furthermore, the present application also proposes that in the gelled base material: the specific surface area of ​​the steel slag powder is ≥400m 2 / kg; the coal gangue powder is a powder with active SiO2 ≥45% after calcination and a particle size ≤0.075mm.

[0011] Furthermore, the present application also proposes that in the activator: the moisture content of the desulfurized gypsum is ≤0.5%; the specific surface area of ​​the silica fume is 20000m 2 / kg.

[0012] Furthermore, the present application also proposes that in the filler: the particle size of the construction waste recycled micropowder is ≤50 μm; the particle size of the river sand fine powder is ≤0.6 mm.

[0013] Furthermore, the present application also proposes that the dosage of the composite curing agent is 6-12% of the total mass of the fluidized solidified soil, and the 7d unconfined compressive strength is 0.7-1.2MPa, and the 28d unconfined compressive strength is 1.2-2.1MPa.

[0014] Furthermore, the present application also proposes that the weight percentage of the gelling base material is 60-70%, the activator is 9-11%, the function regulator is 6-7%, and the filler is 18-22%.

[0015] Furthermore, the present application also proposes that the ordinary Portland cement is of P·O42.5 grade.

[0016] A method for preparing a composite curing agent comprises the following steps:

[0017] S1. Raw material pretreatment: ball-mill the steel slag powder and coal gangue powder to a specific surface area of ​​400-450m 2 / kg, dry the desulfurized gypsum at 80℃ to a moisture content of 0.3-0.4%;

[0018] S2. Mixing process: put the gelling base material and filler into a vertical mixer, dry mix for 3-5 minutes, add the activator and functional regulator, mix for 5-7 minutes, and control the temperature to ≤40°C;

[0019] S3. Screening and packaging: Pass through a 0.6mm square hole sieve and seal the package.

[0020] Furthermore, the present application also proposes that the dry mixing time in the mixing process is 4-8 minutes and the mixing temperature is controlled at 30-40°C.

[0021] The invention discloses an application of a composite curing agent in fluidized solidified soil in municipal engineering. The fluidized solidified soil is used for pipe trench backfill or roadbed cushion.

[0022] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are as follows:

[0023] 1. In the cementitious base material, ordinary Portland cement serves as the primary strength source. Fine steel slag and fly ash enhance cementitious properties through the pozzolanic effect, and calcined coal gangue powder enhances activity. The activator stimulates the activity of the solid waste through the synergistic effect of sulfate ions in desulfurized gypsum and nanoparticles in silica fume. Sodium carbonate adjusts the pH of the system to promote the reaction. Among the functional modifiers, water reducers reduce the water-cement ratio to improve fluidity, retarders delay setting time to ensure workability, and early strength accelerators accelerate early strength development. Recycled micropowder and fine river sand in the filler not only reduce costs but also improve material density through the micro-aggregate effect. These components are mixed in appropriate proportions to form an adjustable system. Adjusting the ratio of cementitious base material to filler material controls the overall strength level. The amount of activator and functional modifier used adjusts the hydration process and workability.

[0024] This solution overcomes the limitations of traditional curing agents, which rely on high-cost cement, by reducing material costs through the synergistic utilization of solid waste. Compared to curing agent designs that simply pursue high strength, this solution achieves adjustable strength by adjusting the proportions of multiple components, better meeting the actual needs of municipal engineering projects. Compared to the low solid waste utilization rate of existing technologies, this solution achieves efficient utilization of multiple types of solid waste, such as steel slag, fly ash, and coal gangue. In terms of performance control, this solution solves the problem of the single working performance of traditional curing agents through the combined use of functional regulators.

[0025] Through the above technical solutions, this application effectively reduces the material cost of fluidized solidified soil and realizes the efficient resource utilization of industrial solid waste. The curing agent system can flexibly adjust the strength index according to the project requirements to avoid waste caused by redundant material performance. The introduction of composite functional regulators significantly improves the working performance of fluidized solidified soil, enabling it to adapt to the requirements of different construction environments. The reasonable ratio of fillers further optimizes the economy while ensuring material performance, providing a more practical fluidized solidified soil solution for municipal engineering.

[0026] 2. This solution fully unleashes the gelling activity of industrial solid waste through surface area control and innovative calcination processes, reducing cement usage while maintaining necessary mechanical properties. This effectively increases the utilization rate of solid wastes such as steel slag and coal gangue, reduces reliance on cement-based materials, and reduces the cost of the gelling system by approximately 20-30%. The full release of active components ensures the stable development of the early strength of the solidified soil, while particle size control prevents fluidity loss due to particle agglomeration, ensuring that the material meets the strength requirements of municipal engineering projects while maintaining excellent workability.

[0027] 3. This solution achieves optimal activation of the activator components by precisely controlling the dryness of the desulfurized gypsum and the fineness of the silica fume. This ensures that the activator maintains component stability during storage and rapidly releases its active ingredients upon use, significantly improving the activation efficiency of industrial solid wastes such as steel slag powder. This reduces the cost of repeated additions due to material failure and increases the utilization rate of industrial solid waste in the cementitious system, ultimately effectively controlling the production costs of fluidized solidified soil.

[0028] 4. This solution achieves efficient utilization of construction waste and ensures compatibility between the filling system and the cementitious base material through dual particle size control. This application effectively solves the problem of construction performance fluctuations caused by the unreasonable particle size distribution of traditional curing agent fillers. The fineness control of recycled construction waste micropowder improves the utilization rate of industrial solid waste, and the particle size limitation of river sand fine powder avoids material segregation. The synergistic effect of the two enables the fluidized solidified soil to maintain stable self-leveling properties during trench backfill operations, while reducing the consumption of natural sand and gravel resources.

[0029] 5. This solution avoids excessive use of cementitious materials by limiting the dosage range and strength interval. Furthermore, through the synergistic effect of functional modifiers, the solidified soil significantly reduces cement usage and production costs while still meeting the low-strength requirements of municipal engineering projects. This enables the economical application of fluidized solidified soil in scenarios such as trench backfill. The curing agent dosage can be flexibly adjusted within a range of 6-12% based on project requirements. A 7-day strength of 0.7 MPa or higher is sufficient for construction machinery to travel, and a 28-day strength of 1.2 MPa or higher meets the long-term load-bearing requirements of the roadbed, avoiding the material waste associated with traditional high-strength curing agents.

[0030] 6. This proposal significantly increases the amount of industrial solid waste while ensuring fluidity by increasing the proportion of the cementitious base material and further optimizing the ratios of its components. The precise ratio of activator and functional regulator minimizes material waste. While meeting the municipal engineering requirement of 7-day strength of fluidized solidified soil of 0.7-1.2 MPa, this proposal increases the utilization of solid wastes such as recycled construction waste micropowder and steel slag micropowder to 45-55% of the total cementitious base material mass, reducing material costs by approximately 18-25%. Dynamic regulation of the functional regulator allows for adaptation to the setting time and strength development requirements of different construction scenarios.

[0031] 7. While ensuring the performance and mechanical properties of fluidized solidified soil, this application effectively addresses the high cost and performance issues of conventional curing agents caused by improper cement grade selection, by selecting a cement type with the appropriate strength grade. This selection creates a synergistic effect between the cementitious system, activator, and functional regulator, meeting the basic early strength requirements for trench backfilling and other applications while avoiding the waste of resources caused by excessive pursuit of high strength.

[0032] 8. This application uses a step-by-step mixing process to first complete the physical mixing of the cementitious base material and the filler, and then introduces the functional additives, thereby avoiding the adsorption competition caused by premature contact between the water reducer and the stimulator. Existing processes mostly use a single mixing method, which makes it difficult to ensure the uniformity of dispersion of the components. This application controls the mixing time and temperature to enable the components to complete the interface bonding in a predetermined order. This application achieves efficient activation and utilization of industrial solid waste materials. The ball milling treatment of steel slag powder and coal gangue powder significantly improves their ability to participate in hydration reactions. The staged mixing process ensures the effective dispersion of the functional regulator in the cementitious system and avoids performance fluctuations caused by excessive local concentrations. The precise drying treatment of desulfurized gypsum maintains the stability of the stimulator system and prevents performance degradation during storage. The screening process effectively controls the particle size distribution of the finished curing agent and ensures its uniform dispersion in the fluidized solidified soil, thereby meeting the requirements of municipal engineering for material working performance and strength development. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below in the form of examples.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0035] In addition, in the description of the present invention, it should be understood that the terms "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0037] In the present invention, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "implementation method", "embodiment", "one embodiment", "example" or "specific example" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0038] The invention discloses an adjustable composite solidifying agent for fluidized solidified soil, which is composed of the following components by weight percentage: a cementitious base material: 50-70%; an activator: 8-12%; a functional regulator: 5-8%; and a filler: 15-25%. The cementitious base material comprises 15-25% of ordinary Portland cement, 10-20% of steel slag powder, 10-15% of fly ash, and 5-10% of coal gangue powder; the activator comprises 4-6% of desulfurized gypsum, 2-4% of silica fume, and 2-3% of sodium carbonate; the functional regulator comprises 1-2% of a lignin sulfonate water reducer, 0.5-1% of a sucrose retarder, and 0.5-1% of a sodium sulfate early strength agent; and the filler comprises 10-15% of recycled construction waste powder and 5-10% of river sand fine powder.

[0039] Those skilled in the art will understand that a cementitious base material refers to a composite cementitious system composed of various solid wastes and cement. Specifically, it can be achieved by a synergistic combination of ordinary Portland cement, steel slag powder, fly ash, and coal gangue powder. The activity of the steel slag powder is activated by a subsequent stimulant, and the calcination of the coal gangue powder can enhance its pozzolanic activity. An stimulant refers to a composite stimulating system that promotes the hydration reaction of solid waste materials. Specifically, it can be achieved by a combination of desulfurized gypsum to provide sulfate stimulation, silica fume to provide the pozzolanic effect of nano-scale silica, and sodium carbonate to adjust the alkalinity of the system. A functional regulator refers to a combination of additives that regulate the working properties of fluidized solidified soil. Specifically, it can be achieved by the synergistic effect of lignin sulfonate water reducer to improve fluidity, sucrose to delay setting time, and sodium sulfate to accelerate early strength development. Filler refers to an inert material that reduces material cost and improves particle grading. Specifically, it can be achieved by a combination of recycled construction waste micropowder to replace part of the cementitious material and fine river sand powder to adjust the fineness of the system.

[0040] Specifically, ordinary Portland cement serves as the primary strength source in the cementitious matrix, while steel slag powder and fly ash enhance cementitious properties through the pozzolanic effect, and coal gangue powder is calcined to enhance its activity. The activator stimulates the activity of the solid waste through the synergistic action of sulfate ions in desulfurized gypsum and nanoparticles in silica fume, while sodium carbonate adjusts the pH of the system to promote the reaction. Among the functional regulators, water reducers reduce the water-cement ratio to improve fluidity, retarders delay setting time to ensure construction operability, and early strength agents accelerate early strength development. The recycled micropowder and fine river sand in the filler not only reduce costs but also improve material density through the micro-aggregate effect. The components are mixed in proportion to form an adjustable system. The overall strength level can be controlled by adjusting the ratio of the cementitious matrix to the filler. The amount of activator and functional regulator used can be used to adjust the hydration process and construction performance.

[0041] This solution overcomes the limitations of traditional curing agents, which rely on high-cost cement, by reducing material costs through the synergistic utilization of solid waste. Compared to curing agent designs that simply pursue high strength, this solution achieves adjustable strength by adjusting the proportions of multiple components, better meeting the actual needs of municipal engineering projects. Compared to the low solid waste utilization rate of existing technologies, this solution achieves efficient utilization of multiple types of solid waste, such as steel slag, fly ash, and coal gangue. In terms of performance control, this solution solves the problem of the single working performance of traditional curing agents through the combined use of functional regulators.

[0042] Through the above technical solutions, this application effectively reduces the material cost of fluidized solidified soil and realizes the efficient resource utilization of industrial solid waste. The curing agent system can flexibly adjust the strength index according to the project requirements to avoid waste caused by redundant material performance. The introduction of composite functional regulators significantly improves the working performance of fluidized solidified soil, enabling it to adapt to the requirements of different construction environments. The reasonable ratio of fillers further optimizes the economy while ensuring material performance, providing a more practical fluidized solidified soil solution for municipal engineering.

[0043] As a preferred embodiment of the gelled substrate in this application, in the gelled substrate: the specific surface area of ​​the steel slag powder is ≥ 400m 2 / kg; coal gangue powder refers to a powder with active SiO2 ≥ 45% after calcination and a particle size ≤ 0.075mm. The specific surface area of ​​steel slag powder refers to the sum of the surface areas of particles per unit mass, which can be achieved by grinding the steel slag to the target fineness through ball milling. By increasing the specific surface area, the active sites on the particle surface can be increased, promoting hydration reactions, thereby improving the early strength development of the cementitious system. The active SiO2 content of coal gangue powder refers to the content of amorphous silicon dioxide after calcination, which can be achieved by treating the coal gangue with a high-temperature calcination activation process to cause it to undergo a dehydroxylation reaction to generate active components. Particle size control is achieved through a screening process. Fine particles are conducive to shortening the hydration reaction path and improving the uniformity of the material system.

[0044] Specifically, after the steel slag powder is ball-milled to meet the specific surface area requirements, its surface defects and active sites increase significantly, and it can quickly release Ca under alkaline excitation conditions. 2+ 、Fe 3+ Metal ions such as SiO2 react with the active silicon and aluminum components in fly ash through a secondary hydration reaction. After calcination and activation, the active SiO2 reacts with the cement hydration product, Ca(OH)2, to form CSH gel. The micron-sized particle size ensures uniform dispersion within the slurry, preventing the formation of localized weak zones. This synergistic combination optimizes the reaction kinetics of the cementitious system, achieving controllable strength while maintaining performance.

[0045] This solution fully unleashes the gelling activity of industrial solid waste through surface area control and innovative calcination processes, reducing cement usage while maintaining necessary mechanical properties. This effectively increases the utilization rate of solid wastes such as steel slag and coal gangue, reduces reliance on cement-based materials, and reduces the cost of the gelling system by approximately 20-30%. The full release of active components ensures the stable development of the early strength of the solidified soil, while particle size control prevents fluidity loss due to particle agglomeration, ensuring that the material meets the strength requirements of municipal engineering projects while maintaining excellent workability.

[0046] As a preferred embodiment of the activator in this application, the activator includes: the moisture content of desulfurized gypsum is ≤0.5%; the specific surface area of ​​silica fume is 20000m 2 / kg. The moisture content of desulfurized gypsum refers to the percentage of water in the desulfurized gypsum to its total mass. This can be achieved through a drying process, for example, drying at 80°C. This parameter can be controlled to prevent excessive moisture from affecting the reaction efficiency of the active components of the activator and the cementitious material. The specific surface area of ​​silica fume refers to the total surface area per unit mass of silica fume particles, which can be achieved through ultrafine grinding. A higher specific surface area increases the contact area between the silica fume and the cementitious substrate, promoting the reactivity of the pozzolanic reaction.

[0047] Specifically, during the preparation of the activator, by controlling the moisture content of the desulfurized gypsum to no more than 0.5%, it is possible to effectively avoid the pre-hydration reaction of the moisture with the cementitious material during storage, thus ensuring the stability of the activator components. At the same time, the specific surface area of ​​the silica fume reaches 20,000 m 2 / kg, the number of its surface active sites increases significantly, making it easier to undergo secondary hydration reactions with the active components in the steel slag powder in an alkaline environment, forming a dense hydration product structure. The coordinated control of these two parameters allows the activator to maintain the chemical stability of the components while also having sufficient reactivity.

[0048] This solution achieves optimal activation of the activator components by precisely controlling the dryness of the desulfurized gypsum and the fineness of the silica fume. This ensures the stability of the activator components during storage and the rapid release of active ingredients upon use, significantly improving the activation efficiency of industrial solid wastes such as steel slag fines. This reduces the cost of repeated additions due to material failure and increases the utilization rate of industrial solid waste in the cementitious system, ultimately effectively controlling the production costs of fluidized solidified soil.

[0049] As a specific embodiment of the filler, in the filler: the particle size of the recycled micropowder from construction waste is ≤50μm; the particle size of the river sand fine powder is ≤0.6mm. The particle size control of the recycled micropowder from construction waste is to grind the crushed construction waste so that its maximum particle size does not exceed 50 microns. Specifically, a ball mill can be used for crushing and grading, and screening equipment can be used to achieve particle size control. This particle size range can ensure that the micropowder particles are evenly dispersed in the solidified soil, avoiding the formation of stress concentration points inside the material due to excessively large particles. The particle size control of the river sand fine powder is to retain fine particles with a particle size of less than 0.6 mm after crushing and screening the natural river sand. Specifically, a vibrating screen can be used for grading. This particle size range not only ensures the skeleton support function of the filler, but also does not affect the pumping construction performance of the fluid solidified soil due to excessively coarse particles.

[0050] The particle size of recycled micropowder from construction waste is limited to no more than 50 microns. This ensures that the micropowder formed after ultrafine grinding of discarded concrete, bricks, and tiles has a high specific surface area, allowing it to fully participate in the cementation reaction. In the fluidized solidified soil system, the micropowder particles fill the gaps in the cementitious material, improving the material's density through a physical filling effect. The upper limit of the particle size of the river sand fine powder is set at 0.6 mm, which not only retains the skeletal support capacity of the sand particles but also prevents the sedimentation and stratification of coarse particles during pumping. The coordinated control of the particle sizes of the two fillers ensures that the solidified soil maintains fluidity while also possessing the necessary volume stability.

[0051] Compared with the existing technology, the recycled aggregates from construction waste in traditional methods are mostly in the form of coarse particles, and their particle size distribution range is usually between 0.15-4.75 mm. This large-particle filler will significantly reduce the fluidity of the fluidized solidified soil. The existing technology lacks clear requirements for the particle size control of river sand fine powder, and often directly adopts the original grading of natural river sand, resulting in unstable working performance of the solidified soil. This solution not only achieves the efficient utilization of construction waste through dual particle size control, but also ensures the compatibility of the filling system with the cementitious base material. This application effectively solves the problem of construction performance fluctuations caused by the unreasonable particle size distribution of traditional curing agent fillers. The fineness control of recycled micropowder from construction waste improves the utilization rate of industrial solid waste, and the particle size limitation of river sand fine powder avoids material segregation. The synergistic effect of the two enables the fluidized solidified soil to maintain stable self-leveling properties during trench backfill operations, while reducing the consumption of natural sand and gravel resources.

[0052] As a preferred embodiment of the present application, the dosage of the composite curing agent is 6-12% of the total mass of the fluidized solidified soil, and the 7d unconfined compressive strength is 0.7-1.2MPa, and the 28d unconfined compressive strength is 1.2-2.1MPa. The dosage refers to the mass proportion of the composite curing agent in the fluidized solidified soil, which can be achieved by adjusting the ratio of the cementitious base material to the filler. For example, controlling the dosage within the range of 6-12% can balance the material cost and engineering performance requirements. The unconfined compressive strength refers to the ultimate strength of the specimen under axial pressure without lateral constraints, which can be achieved by adjusting the ratio of the stimulator and the functional regulator. For example, the 7d strength is set to 0.7-1.2MPa to meet the early construction bearing requirements, and the 28d strength is set to 1.2-2.1MPa to adapt to long-term load requirements.

[0053] The composite curing agent dosage range is determined by the synergistic effect of the cementitious base material and filler, ensuring fluidity while achieving graded strength control. The combination of desulfurized gypsum and silica fume in the activator accelerates early hydration, while the retarder and early strength accelerator in the functional modifier precisely control the setting time and strength development curve. By adjusting the total curing agent dosage, the fluidity and strength requirements of different projects can be matched within a range of 6-12%.

[0054] Compared with existing technologies, traditional curing agents usually use fixed dosages and pursue high strength indicators. For example, some solutions require the 28d strength to exceed 5MPa, resulting in serious material waste. This solution avoids excessive use of cementitious materials by limiting the dosage range and strength interval. At the same time, through the synergistic effect of functional regulators, the solidified soil can significantly reduce cement consumption and production costs while meeting the low-strength requirements of municipal engineering. The economic application of fluidized solidified soil in scenarios such as trench backfilling is realized. The dosage of curing agent can be flexibly adjusted within the range of 6-12% according to engineering requirements. When the 7d strength reaches above 0.7MPa, the requirements for construction machinery travel can be met. When the 28d strength reaches above 1.2MPa, the long-term bearing requirements of the roadbed cushion can be met, avoiding the material waste caused by traditional high-strength curing agents.

[0055] As an optimal embodiment of this application, the weight percentage of the cementitious base material is 60-70%, the activator is 9-11%, the functional regulator is 6-7%, and the filler is 18-22%. When the proportion of the cementitious base material is increased to 60-70%, the active components of the steel slag powder and the coal gangue powder form more hydration products under the action of the activator, thereby strengthening the skeleton structure of the solidified soil; the proportion of the activator is controlled within the range of 9-11%, which can fully stimulate the potential activity of the solid waste material while avoiding excessive addition leading to increased costs; when the functional regulator accounts for 6-7%, the water-reducing agent reduces the water-cement ratio while the synergistic effect of the retarder and the early strength agent enables the solidified soil to achieve orderly strength growth while maintaining fluidity; when the filler accounts for 18-22%, the grading optimization of the recycled construction waste powder and the river sand fine powder reduces the porosity and improves the density.

[0056] By increasing the proportion of cementitious base material and further optimizing the proportions of its components, this solution significantly increases the amount of industrial solid waste while ensuring fluidity. The precise ratio of activator and functional regulator also avoids material waste. While meeting the 7-day strength requirement of 0.7-1.2 MPa for fluidized solidified soil in municipal projects, this application increases the utilization rate of solid wastes such as recycled construction waste micropowder and steel slag micropowder to 45-55% of the total cementitious base material mass, reducing material costs by approximately 18-25%. Furthermore, through dynamic regulation of the functional regulator, the setting time and strength development requirements of different construction scenarios can be adapted.

[0057] Preferably, ordinary Portland cement is P·O42.5 grade. P·O42.5 grade ordinary Portland cement is ordinary Portland cement with a strength grade of 42.5, as specified in the GB175 standard. It is made by grinding clinker, gypsum, and admixtures according to standard proportions. This strength grade has a 3-day compressive strength of no less than 17 MPa and a 28-day compressive strength of no less than 42.5 MPa, balancing early strength development with later strength growth requirements.

[0058] Ordinary Portland cement, as the core component of the cementitious base material, has a strength grade that directly impacts the early structural development rate and ultimate bearing capacity of the solidified soil. Using P·O42.5 grade cement avoids both the early strength deficiency associated with lower-grade cement and the cost waste associated with higher-grade cement, thus meeting the strength requirements of municipal projects while controlling material costs.

[0059] Specifically, during the preparation of fluidized solidified soil, the hydration reaction of P·O42.5 grade cement generates CSH gel and ettringite crystals, which, together with active components such as finely divided steel slag and fly ash, form a cementitious network. The calcium ion release rate of this strength grade matches the pozzolanic effect of industrial solid waste, ensuring that the 7-day strength meets engineering requirements while avoiding volume deformation caused by excessive hydration heat. When combined with the sucrose retarder in the functional modifier, the setting time can be precisely controlled to suit different construction environments.

[0060] Compared to existing technologies, traditional solutions often use sulphoaluminate cement or 52.5-grade ordinary Portland cement. The former is expensive and hydrates too quickly, while the latter's excessive strength leads to material waste. However, PO42.5-grade cement, while meeting the 7-day strength target of 0.7-1.2 MPa, can reduce the amount of cementitious materials used by approximately 15% compared to 52.5-grade cement. Its standardized production process also ensures consistent quality.

[0061] Through the above technical solution, this application effectively addresses the high cost and performance issues of traditional curing agents caused by improper cement grade selection, while ensuring the performance and mechanical properties of fluidized solidified soil. By selecting a cement type with the appropriate strength grade, this solution effectively addresses the high cost and performance issues of traditional curing agents caused by improper cement grade selection. This selection creates a synergistic effect between the gelling system, the activator, and the functional regulator, meeting the basic early strength requirements for trench backfilling and other applications while avoiding the waste of resources caused by excessive pursuit of high strength.

[0062] A method for preparing a composite curing agent comprises the following steps:

[0063] S1. Raw material pretreatment: ball-mill the steel slag powder and coal gangue powder to a specific surface area of ​​400-450m 2 / kg, dry the desulfurized gypsum at 80℃ to a moisture content of 0.3-0.4%;

[0064] S2. Mixing process: put the gelling base material and filler into a vertical mixer, dry mix for 3-5 minutes, add the activator and functional regulator, mix for 5-7 minutes, and control the temperature to ≤40°C;

[0065] S3. Screening and packaging: Pass through a 0.6mm square hole sieve and seal the package.

[0066] Among them, ball milling refers to the use of mechanical grinding to refine steel slag powder and coal gangue powder to the target specific surface area range. Specifically, this can be achieved by using a planetary ball mill, and the powder activity can be adjusted by controlling the grinding time and speed. Desulfurization gypsum drying refers to the use of hot air circulation equipment to remove free moisture. Specifically, a belt dryer can be used for continuous treatment at a set temperature to reduce the effect of moisture content on the activity of the activator. The dry mixing process refers to first mixing the gelling base material and the filler in a liquid-free phase. Specifically, a vertical mixer is used to achieve uniform dispersion of the materials through the shearing action of the blades to avoid premature contact with liquid additives and causing agglomeration. Temperature control refers to monitoring the material temperature during the mixing process. Specifically, a circulating water cooling system or intermittent stirring method can be used to maintain thermal balance to prevent high temperature from causing premature reactions between components.

[0067] Specifically, during the raw material pretreatment stage, steel slag fine powder and coal gangue powder are ball-milled to achieve a specific specific surface area, effectively enhancing their reactivity in the cementitious system. After low-temperature drying, the moisture content of the desulfurized gypsum is reduced to 0.3-0.4%, ensuring that the activator components do not deliquesce and agglomerate during storage. During the mixing process, the cementitious base material and filler are first dry-mixed, so that the recycled construction waste fine powder and river sand fine powder are evenly coated on the surface of the cement particles, forming a stable skeleton structure. The activator and functional modifier are then added for a secondary mixing. By controlling the mixing time, components such as silica fume and sodium carbonate are fully dispersed, and the lignin sulfonate water reducer is evenly adsorbed on the particle surface. During the screening and packaging stage, a 0.6mm square hole sieve is used to remove agglomerated particles to ensure that the fineness of the finished curing agent meets construction requirements.

[0068] Compared with the existing technology, the traditional curing agent preparation process does not perform ball milling activation treatment on steel slag powder and coal gangue powder, resulting in insufficient release of the activity of the solid waste materials. In the existing technology, desulfurization gypsum often directly uses undried raw materials, which easily causes the activator component to agglomerate and fail. The present application uses a step-by-step mixing process to first complete the physical mixing of the cementitious base material and the filler, and then introduces the functional additives, thereby avoiding the adsorption competition caused by premature contact between the water reducer and the activator. The existing process mostly uses a single mixing method, which makes it difficult to ensure the uniformity of dispersion of each component. The present application controls the mixing time and temperature to enable the components to complete interfacial bonding in a predetermined order. The present application realizes the efficient activation and utilization of industrial solid waste materials. The ball milling treatment of steel slag powder and coal gangue powder significantly improves their ability to participate in hydration reactions. The staged mixing process ensures the effective dispersion of the functional regulator in the cementitious system, avoiding performance fluctuations caused by excessive local concentration. The precise drying treatment of the desulfurization gypsum maintains the stability of the activator system and prevents performance degradation during storage. The screening process effectively controls the particle size distribution of the finished curing agent, ensuring its uniform dispersion in the fluidized solidified soil, thereby meeting the requirements of municipal engineering for material performance and strength development.

[0069] As a preferred method for preparing the composite curing agent of the present application, the dry mixing time in the mixing process is 4-8 minutes, and the mixing temperature is controlled at 30-40°C. The cementitious base material and the filler are first dry-mixed in a vertical mixer. By setting a mixing cycle of 4-8 minutes, solid waste materials such as steel slag powder and coal gangue powder are mixed with recycled construction waste powder to form a uniform mixture. Subsequently, the activator and functional regulator are added while maintaining stirring. The material temperature is maintained in the range of 30-40°C throughout the mixing process through a circulating water cooling system to prevent organic components such as the lignin sulfonate water reducer from becoming ineffective due to overheating.

[0070] In some embodiments, the dry mixing stage can be set to 6 minutes with a temperature of 35°C to achieve optimal dispersion of fly ash and river sand. When processing highly reactive steel slag powder, the dry mixing time can be shortened to 5 minutes and the upper temperature limit set to 38°C to prevent premature hydration.

[0071] Through the above technical solution, this application effectively solves the problems of uneven material dispersion and thermal damage in the preparation process of traditional curing agents, enables solid waste materials such as recycled micropowder of construction waste to stably participate in the hydration reaction, and provides controllable process conditions for the production of composite curing agents with different ratios.

[0072] A composite curing agent is used in fluidized solidified soil for municipal engineering projects. The fluidized solidified soil is used for trench backfill or roadbed cushioning. The composite curing agent forms a stable hydration product network structure in the fluidized solidified soil through the synergistic effect of the cementitious base material and the activator. The steel slag powder and fly ash in the cementitious base material continuously release active ingredients under the action of the activator, while the construction waste recycled powder and river sand fine powder in the filler serve as skeleton support materials. The functional regulator achieves a dynamic balance between fluidity and strength by controlling the hydration reaction rate. In the trench backfill scenario, the high fluidity of the fluidized solidified soil enables it to fully fill the gaps in the pipe wall, while the slow-setting properties ensure the construction time window; in the roadbed cushioning scenario, the early strength properties accelerate the formation of the structure, while the dense structure formed by the recycled powder and river sand fine powder improves the compressive performance.

[0073] This solution significantly reduces raw material costs while ensuring the necessary engineering performance by optimizing the proportion of the cementitious system and solid waste, while avoiding the material waste caused by the pursuit of high strength in traditional technologies. In addition, the precise regulation of the functional regulator enables the fluidized solidified soil to adapt to the differentiated needs of different construction scenarios, overcoming the inflexible regulation defects of existing technologies. It solves the problems of high cost, low solid waste utilization and poor performance adaptability of traditional curing agents in municipal engineering. The composite curing agent reduces material costs and meets environmental protection requirements through the efficient utilization of low-cost solid waste; through the coordinated regulation of functional components, the fluidized solidified soil has high fluidity, controllable strength development and construction adaptability, accurately matching the core requirements of trench backfill and roadbed cushion for material performance.

[0074] As a best embodiment of this application,

[0075] Example 1, the components and proportions are shown in Table 1:

[0076]

[0077] (Table 1)

[0078] The preparation method of this preferred embodiment specifically comprises the following steps:

[0079] In the first step, steel slag powder and coal gangue powder are ball-milled to a specific surface area of ​​420m4 / kg;

[0080] In the second step, the desulfurized gypsum is dried at 80°C to a moisture content of 0.4%;

[0081] In the third step, the gelling base material and the filler are put into a vertical mixer and dry mixed for 4 minutes, and the activator and the functional regulator are added and mixed for 6 minutes, and the temperature is controlled at 38°C;

[0082] The fourth step is to pass through a 0.6mm square hole sieve and seal the package.

[0083] The performance test results of this embodiment are:

[0084] 7d compressive strength: 0.98MPa, 28d compressive strength: 1.78MPa; permeability coefficient: ≤5×10 -3 cm / s; solid waste utilization rate: 30%, cost: 308 yuan / ton.

[0085] The advantages of this embodiment are:

[0086] The strength reaches the standard quickly: with a cement content of 25%, combined with silica fume and sodium sulfate early strength agents, the 7d strength is close to the upper limit of municipal engineering (1.2MPa), which is suitable for scenarios where backfilling is urgently needed.

[0087] Balanced performance: taking into account both fluidity and strength, meeting the requirements of "flowing" construction and early strength.

[0088] Example 2: basically the same as Example 1, except that:

[0089] The proportion of cementitious base material is reduced to 50%: cement is reduced to 15%, fly ash is increased to 15%, and coal gangue powder is increased to 10%; the proportion of filler is increased to 25%: construction waste recycled fine powder is 12%, and river sand fine powder is 8%; the amount of functional regulator is reduced: water reducer 1%, sucrose 0.5%, and sodium sulfate 0.5%.

[0090] The performance comparison between Example 2 and Example 1 is shown in Table 2:

[0091]

[0092] (Table 2)

[0093] Conclusion: Compared with Example 1, Example 2 has the positive effect of significant cost advantage, is suitable for roadbed cushion layers with low strength requirements, and can absorb an additional 0.05 tons of fly ash per ton of solidified soil.

[0094] The negative effect is that the early strength increases slowly, requiring extended curing time (e.g., 7d strength is 0.7MPa), but the 28d strength (1.12MPa) still meets the requirements.

[0095] Example 3: Basically the same as Example 1, except that the activator is adjusted: silica fume is increased to 3%, river sand fine powder is increased to 10%; cementitious base material: cement is reduced to 20%, steel slag powder is reduced to 15%; filler: construction waste recycled powder is reduced to 10%.

[0096] The performance comparison between Example 3 and Example 1 is shown in Table 3:

[0097]

[0098] (Table 3)

[0099] Example 4: Basically the same as Example 1, except that the curing agent dosage is reduced to 6% (8% in the best embodiment), and the component ratio remains the same as that of Example 1 (cement 25%, steel slag powder 20%, etc.).

[0100] The performance comparison between Example 4 and Example 1 is shown in Table 4:

[0101]

[0102] (Table 4)

[0103] Anything not described in the present invention can be achieved by adopting or drawing on existing technologies.

[0104] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An adjustable fluidized soil solidification composite curing agent, characterized in that: By weight percentage, it is composed of the following components: Gelling base material: 50-70%; activator: 8-12%; function regulator: 5-8%; filler: 15-25%; The cementitious base material comprises 15-25% of ordinary Portland cement, 10-20% of steel slag powder, 10-15% of fly ash, and 5-10% of coal gangue powder; The activator comprises 4-6% desulfurized gypsum, 2-4% silica fume and 2-3% sodium carbonate; The functional regulator includes 1-2% lignin sulfonate water reducer, 0.5-1% sucrose retarder, and 0.5-1% sodium sulfate early strength agent; The filler comprises 10-15% of recycled construction waste micropowder and 5-10% of river sand fine powder.

2. The adjustable fluidized soil solidification composite curing agent according to claim 1, characterized in that: In the gelled base material: The specific surface area of ​​the steel slag powder is ≥400m 2 / kg; The coal gangue powder is a powder with active SiO2≥45% and a particle size≤0.075mm after calcination.

3. The adjustable fluidized soil solidification composite curing agent according to claim 1, characterized in that: In the exciter: The moisture content of the desulfurized gypsum is ≤0.5%; The specific surface area of ​​the silica fume is 20000m 2 / kg.

4. The adjustable fluidized soil solidification composite curing agent according to claim 1, characterized in that: In the filler: The particle size of the construction waste recycled micropowder is ≤50 μm; The particle size of the river sand fine powder is ≤0.6 mm.

5. The adjustable fluidized soil solidification composite curing agent according to claim 1, characterized in that: The addition amount of the composite curing agent is 6-12% of the total mass of the fluidized solidified soil, and the 7d unconfined compressive strength is 0.7-1.2MPa, and the 28d unconfined compressive strength is 1.2-2.1MPa.

6. The adjustable fluidized soil solidification composite curing agent according to claim 1, characterized in that: The weight percentage of the gelling base material is 60-70%, the weight percentage of the activator is 9-11%, the weight percentage of the functional regulator is 6-7%, and the weight percentage of the filler is 18-22%.

7. The adjustable fluidized soil solidification composite curing agent according to claim 2, characterized in that: The ordinary Portland cement is of P·O42.5 grade.

8. The method for preparing the composite curing agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Raw material pretreatment: ball-mill the steel slag powder and coal gangue powder to a specific surface area of ​​400-450m 2 / kg, dry the desulfurized gypsum at 80℃ to a moisture content of 0.3-0.4%; S2. Mixing process: put the gelling base material and filler into a vertical mixer, dry mix for 3-5 minutes, add the activator and functional regulator, mix for 5-7 minutes, and control the temperature to ≤40°C; S3. Screening and packaging: Pass through a 0.6mm square hole sieve and seal the package.

9. The method for preparing the composite curing agent according to claim 8, characterized in that: The dry mixing time in the mixing process is 4-8 minutes, and the mixing temperature is controlled at 30-40°C.

10. Use of the composite curing agent according to any one of claims 1 to 7 in fluidized solidified soil in municipal engineering, characterized in that: The fluidized solidified soil is used for trench backfill or roadbed cushion.

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