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CN-121974644-A - High-strength fluid-state solidified soil and preparation method thereof

CN121974644ACN 121974644 ACN121974644 ACN 121974644ACN-121974644-A

Abstract

The application relates to the technical field of building materials and solid waste resource utilization, and discloses high-strength fluid solidified soil and a preparation method thereof, comprises a composite curing agent including slag powder, ordinary Portland cement, quicklime, fly ash, red mud micropowder, anhydrous sodium sulfate, anhydrous calcium chloride, enteric-coated expanded microbeads and loaded chemical trigger microbeads. Wherein, the enteric expanded microbeads are provided with a pH sensitive coating layer, and rigid excitation liquid is adsorbed in the supported chemical trigger microbeads. The preparation method relates to the granulation coating, carrier adsorption and low-speed forced stirring process of the microbeads. The application delays the expansion of the microbeads by utilizing the pH change of the system, ensures the initial fluidity, generates a rigid shell layer by the reaction of ions released by the microbeads and the excitation liquid in the later period, converts the soft expansion into a rigid support, obviously improves the compressive strength and the volume stability of the solidified soil, and realizes the efficient recycling of engineering slurry.

Inventors

  • CHEN DEHUA

Assignees

  • 深圳市鲲鹏环保科技有限公司

Dates

Publication Date
20260505
Application Date
20260306

Claims (10)

  1. 1. The high-strength fluid-state solidified soil is characterized by being prepared from raw materials comprising engineering waste slurry and a composite curing agent; The raw materials comprise the following components in parts by weight: 100 parts of engineering waste mud; 5-25 parts of a composite curing agent; the composite curing agent comprises the following components in parts by weight: 40-70 parts of slag powder; 6-15 parts of ordinary Portland cement; 3-10 parts of quicklime; 4-10 parts of fly ash; 4-8 parts of red mud micro powder, wherein the specific surface area is more than or equal to 400m < 2 >/kg, and the pH value is more than or equal to 12.0; 5-15 parts of anhydrous sodium sulfate; 4-8 parts of anhydrous calcium chloride; 0.5-3.0 parts of enteric expanded microbeads; 0.05-0.2 parts of load type chemical trigger microbeads.
  2. 2. The high-strength fluid-state solidified soil according to claim 1, wherein the water content of the engineering waste slurry is 100% -200%, the maximum particle size is less than or equal to 20mm, and the particle content of the particles with the particle size smaller than 0.075mm is more than or equal to 40%.
  3. 3. A high strength fluid-state solidified soil according to claim 1, wherein said enteric expanded microbeads comprise an expandable inner core and a pH-sensitive coating layer coated on the surface of said expandable inner core; the expandable core is formed by rolling and granulating the following raw materials, by weight, 60-80 parts of calcium-based montmorillonite, 10-20 parts of ordinary Portland cement, 10-15 parts of anhydrous gypsum, 5-10 parts of light-burned magnesium oxide and 3-10 parts of calcium oxide; the pH sensitive coating layer is made of polyvinyl acetate phthalate or methacrylic acid copolymer, and the dissolution pH threshold of the pH sensitive coating layer is 11.5-12.5.
  4. 4. The high-strength fluid-state solidified soil according to claim 1, wherein the supported chemical trigger microbeads comprise a salt-tolerant super absorbent resin carrier, a rigid excitation liquid adsorbed inside the carrier and a physical isolation layer positioned on the surface of the carrier; The salt-resistant super absorbent resin carrier is polyacrylate water absorbent resin introduced with 2-acrylamide-2-methylpropanesulfonic acid groups; The rigid excitation liquid is a liquid sodium silicate aqueous solution with the modulus of 2.2-2.6.
  5. 5. A high-strength fluidized solidified soil and a preparation method thereof as claimed in any one of claims 1 to 4, comprising the steps of: S1, weighing the expandable core raw materials according to parts by weight, rolling and granulating by a disc granulator, drying, and spraying pH sensitive coating liquid by a fluidized bed to form enteric expanded microbeads; S2, immersing a salt-resistant type super absorbent resin carrier in the rigid excitation liquid for adsorption, separating after reaching saturated adsorption capacity, and carrying out surface powder coating treatment to obtain load type chemical triggering microbeads; s3, uniformly mixing all the components of the composite curing agent except the supported chemical triggering microbeads according to the weight part of the composition in claim 1 to obtain dry powder, mixing the dry powder with water according to the water-gel ratio of 0.6-0.8, and carrying out low-speed forced mechanical stirring to obtain curing agent slurry; And S4, adding the curing agent slurry into 100 parts by weight of engineering waste slurry, scattering the loaded chemical trigger microbeads in a stirring state, and continuing to perform forced mechanical stirring until the slurry is uniform to obtain the fluid state cured soil.
  6. 6. The method according to claim 5, wherein in step S1, the rotational speed of the disk granulator is 500 to 600r/min, and particles having a particle diameter of 1.0 to 2.0mm are selected as the expandable core.
  7. 7. The method according to claim 5, wherein in step S1, the pH-sensitive coating layer is used in an amount of 5.0 to 10.0 parts by weight based on 100 parts by weight of the expandable core, and the pH-sensitive coating solution is a polyvinyl acetate phthalate solution having a solid content of 5% to 8%.
  8. 8. The method according to claim 5, wherein in the step S2, the solid content of the rigid excitation liquid is 15% -25%, and the rigid excitation liquid contains sodium gluconate stabilizer accounting for 0.2% -0.5% of the total mass of the liquid.
  9. 9. The method according to claim 5, wherein in step S2, the liquid absorption capacity of the salt-tolerant super absorbent resin carrier is controlled to 15 to 25 times of the dry weight; The surface powder coating treatment specifically comprises the steps of mixing the adsorbed microbeads with calcium stearate powder according to the weight ratio of 10:1, so that the powder is adhered to the surfaces of the microbeads.
  10. 10. The preparation method according to claim 5, wherein in step S4, the forced mechanical stirring is performed by a biaxial forced stirrer, the rotation speed of a stirring shaft is controlled to be 30-60 r/min, and the stirring time is controlled to be 90-180S.

Description

High-strength fluid-state solidified soil and preparation method thereof Technical Field The invention relates to the technical field of building materials and solid waste resource utilization, in particular to high-strength fluid solidified soil and a preparation method thereof. Background With the development of urban underground space and the promotion of infrastructure construction, a great amount of engineering waste slurry is generated in the engineering construction processes of cast-in-situ bored piles, underground continuous walls, shield tunnels and the like. The traditional slurry treatment mode is mostly direct outward transportation and discharge or simple dehydration and landfill, not only occupies a large amount of land resources, but also is easy to cause soil and groundwater pollution. The waste slurry is subjected to in-situ solidification treatment to prepare the fluid solidified soil with certain fluidity and strength, and the fluid solidified soil is used for foundation pit backfilling, pipe gallery filling and other projects, and is an effective way for realizing resource utilization of the engineering waste slurry. However, in the existing fluidized solidified soil preparation technology, there is always a contradiction between fluidity maintenance and later strength development and volume stability. Engineering slurries generally contain a large amount of fine clay particles, have a large specific surface area, and have a strong water adsorption capacity. In order to meet the requirements of long distance pumping construction, the solidified soil slurry must have good initial fluidity and slump retention ability. However, after the conventional cement-based or lime-based curing agent is added into the slurry, the hydration reaction is rapid, so that the consistency of the slurry is increased sharply, and the pumping is difficult and even the pipe is blocked. If the water consumption is increased or the retarder is excessively used for maintaining the fluidity, the problems of overlong setting time, low early strength and serious bleeding segregation of the solidified soil are caused, and the requirement of engineering on the strength of the backfill material is difficult to meet. In addition, volume shrinkage cracking is another major technical bottleneck faced by slurry solidified soil. Due to the high water content and high clay content of the slurry, the solidified soil can generate remarkable drying shrinkage and self-shrinkage in the hardening and drying processes, penetrating cracks are extremely easy to induce, and the structural integrity and impermeability are damaged. Although the addition of expansion agents or water-absorbing resins is often used in the concrete field to compensate for shrinkage, these methods have significant drawbacks when applied directly to slurry systems. The traditional swelling agent consumes a large amount of free water in the stirring stage, seriously damages the fluidity of the slurry, and the common water-absorbing high polymer material forms weak gel with low modulus after water absorption swelling. These weak gels, while capable of filling the volume, do not provide rigid support, resulting in collapse of the compression strength of the solidified soil. More seriously, when the environment is dry and dehydrated, the weak gels retract, leaving voids inside the solidified soil, which becomes a structural defect. At the same time, the complex ionic environment in engineering slurries tends to inhibit the activity of conventional functional materials, leading to their failure. Accordingly, there is a need to develop a new slurry curing technique that can achieve both delayed expansion to ensure pumping performance and convert the expansion point to a rigid support to increase strength and volume stability. Disclosure of Invention Aiming at the defects of the prior art, the invention provides high-strength fluid solidified soil and a preparation method thereof, and solves the problems that the fluidity of the existing engineering slurry solidified soil is maintained in construction, the strength is improved after hardening, the volume shrinkage is difficult to control, and the traditional expansion medium is easy to collapse due to the low retraction and modulus. In order to achieve the above purpose, the invention is realized by the following technical scheme: the first aspect of the invention provides a high strength fluid-state solidified soil prepared from raw materials including engineering waste mud and a composite curing agent. The raw materials comprise the following components in parts by weight: 100 parts of engineering waste slurry and 5-25 parts of composite curing agent. The composite curing agent comprises the following components in parts by weight: 40-70 parts of slag powder; 6-15 parts of ordinary Portland cement; 3-10 parts of quicklime; 4-10 parts of fly ash; 4-8 parts of red mud micro powder, wherein the specific surface area o