Multi-scale fiber-reinforced high-fluidity anti-cracking fluid state solidified soil and preparation method thereof
By using multi-scale fiber reinforcement and self-healing interface design, the brittleness and fluidity of fluidized solidified soil were solved, and the preparation of highly fluid and crack-resistant fluidized solidified soil was achieved, improving the crack resistance and durability of the material.
Patent Information
- Application Number
- CN202610146668.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-19
AI Technical Summary
Traditional fluidized solidified soil is brittle and has poor crack resistance. The addition of fibers leads to a decrease in fluidity and insufficient interfacial bonding strength. The dispersion and synergistic effect of nanomaterials are difficult to solve, and the performance of the material is irreversibly degraded after cracking.
By employing a multi-scale fiber reinforcement system, and by coating modified short-cut steel fibers with epoxy resin microspheres and carbon nanotubes to bridge microcracks, combined with rheology modifiers to control fluidity, a high-fluidity, crack-resistant solidified soil with self-healing capabilities was prepared.
While maintaining high fluidity, it significantly improves crack resistance, toughness and durability, achieving dynamic self-repair and reinforcement of the fiber-matrix interface and delaying damage evolution.
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology, and in particular to a multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil and its preparation method. Background Technology
[0002] Fluidized solidified soil, a fluid engineering material composed of excavated soil, solidifying agent, water, and additives, is widely used in engineering fields such as roadbed backfilling, pipeline trench backfilling, and narrow space filling due to its good fluidity and self-compacting properties. Traditional fluidized solidified soil mainly relies on cement and other cementing materials for strength, but its brittleness and poor crack resistance have not been effectively addressed. It is prone to cracking under drying shrinkage, temperature changes, or external forces, which not only affects the overall structural integrity but also provides channels for the intrusion of moisture and corrosive media, seriously threatening the long-term durability of the project.
[0003] To improve crack resistance, the industry commonly employs the method of adding fibers (such as steel fibers, polypropylene fibers, etc.). The addition of fibers can form a randomized support system in the matrix, playing a role in crack prevention and toughening. However, the introduction of conventional fibers often brings new technical challenges: First, the addition of fibers significantly increases the internal friction of the mixture, leading to a sharp decrease in fluidity, sacrificing the core construction advantages of fluidized solidified soil, and even causing fiber agglomeration and material segregation, affecting homogeneity; second, the interfacial bond strength between the fiber and the cementitious matrix is insufficient, making it prone to premature debonding or pull-out during stress, making it difficult to fully realize its reinforcing and toughening potential.
[0004] In recent years, the introduction of nanomaterials (such as carbon nanotubes) has provided new ideas for improving material properties at the microscale, but their dispersion in the matrix and their synergistic effect with macroscopic fibers remain technical challenges. In addition, existing technologies do not pay enough attention to the performance recovery of materials after cracking; once microcracks are formed, the performance of materials will irreversibly degrade.
[0005] Therefore, developing a high-performance fluidized solidified soil with high crack resistance, high toughness, and even a certain degree of self-healing ability has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention
[0006] To address the aforementioned issues, this application provides a multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil and its preparation method.
[0007] In the first aspect, this application provides a multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil, employing the following technical solution: A multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil comprises the following raw materials in parts by weight: The mixture comprises 75-85 parts sand, 10-30 parts cementitious material, 1-3 parts modified chopped steel fiber, 0.05-0.15 parts carbon nanotubes, 0.02-0.04 parts silane coupling agent, 0.35-0.6 parts rheology modifier, and 15-25 parts water; wherein the modified chopped steel fiber is surface modified and its surface is coated with a coating containing epoxy resin microspheres.
[0008] By adopting the above technical solutions, the modified short-cut steel fibers of the epoxy resin microsphere coating can not only significantly improve their dispersibility and interfacial adhesion in the cementitious matrix, effectively prevent cracking and improve macroscopic mechanical properties, but also the carbon nanotubes further fill the pores and bridge the microcracks at the microscale, forming a cross-scale synergistic reinforcement network from nanometer to millimeter level. The rheology modifier precisely controls the rheological properties of the slurry, ensuring high fluidity while inhibiting segregation and sedimentation, so that the material remains uniform and stable during the casting process. Together, they endow the fluidized solidified soil with excellent workability, significant crack resistance and overall durability.
[0009] Optionally, the surface modification method of the chopped steel fiber is as follows: first, the fiber is copper-plated, and then coated with the coating containing epoxy resin microspheres, wherein the particle size of the epoxy resin microspheres is 3-8 μm.
[0010] By adopting the above technical solution, multi-level reinforcement of the fiber-matrix interface is achieved by first plating copper and then coating epoxy resin microspheres. The copper plating treatment not only effectively prevents steel fiber corrosion, but also significantly improves the bonding force between the fiber surface and the epoxy resin microsphere coating, laying a solid foundation for subsequent functional modification. Subsequently, epoxy resin microspheres of a specific particle size play a key role in the coating. During the curing process, they can act as a flexible buffer layer to absorb some stress and reduce the generation of interfacial microcracks. They can also transfer the tensile stress on the fiber to the surrounding cementitious matrix more evenly through their own deformation and friction effect, thereby greatly enhancing the anchoring effect and bridging ability of the fiber, and fundamentally improving the toughness and post-cracking performance of the composite material.
[0011] Optionally, the epoxy resin microspheres are core-shell structured microcapsules, with the core material being a mixture of liquid epoxy resin and a latent curing agent, and the wall material being either polyvinyl alcohol or polyurethane.
[0012] By adopting the above technical solution, when microcracks are generated inside the fluidized solidified soil due to stress and extend to the fiber-matrix interface, the stress at the crack tip will pierce the wall material of the microcapsule, causing the liquid epoxy resin and latent curing agent inside to be released into the crack area. Under the subsequent service environment or the effect of its own reaction heat, these repair agents will cure rapidly, which can not only effectively bond the microcracks and restore the integrity of the matrix, but more importantly, form a tough "in-situ weld point" in the interface area where the fiber debonded, thereby dynamically restoring the bridging effect of the fiber and significantly improving the damage tolerance and long-term durability of the material.
[0013] Optionally, the preparation of the epoxy resin microspheres includes the following steps: S1: Liquid epoxy resin, latent curing agent and emulsifier are added to deionized water and emulsified under high-speed shearing to form a stable epoxy resin emulsion. S2: Add wall material to the emulsion, heat and stir to react, adjust the pH of the system to 6-7, and carry out the polymerization reaction at a constant temperature so that the wall material is deposited on the surface of the epoxy resin droplets and forms a coating; S3: After the reaction is complete, the product is filtered, washed, and dried to obtain powdered epoxy resin microspheres.
[0014] By adopting the above technical solution, the process of first emulsifying to form a stable emulsion and then controlling the polymerization and deposition of the wall material ensures that the final product has a regular core-shell structure and a high degree of integrity. The emulsification step determines the size uniformity of the core material droplets, laying the foundation for the formation of monodisperse microspheres. By precisely controlling the pH and temperature of the reaction environment, the wall material can uniformly and densely coat the surface of each epoxy resin droplet, forming a strong barrier. This structure not only effectively protects the core material from leakage during storage and mixing, but also ensures that the repair agent can only be released in a targeted manner when the material is subjected to stress and cracks occur or the microspheres are mechanically damaged. This achieves precise triggering and efficient repair of self-healing behavior, greatly improving the reliability and service life of the material.
[0015] Optionally, the epoxy resin microspheres include 10-20 parts of liquid epoxy resin, 1-3 parts of latent curing agent, 0.5-1.5 parts of emulsifier, 50-100 parts of deionized water, and 5-10 parts of wall material.
[0016] By employing the above technical solutions, the appropriate ratio of liquid epoxy resin to latent curing agent ensures that the repair agent can fully cross-link and cure after release, forming a high-strength repair. The amount of emulsifier directly affects the stability of the initial emulsion, which is a prerequisite for forming microcapsules with uniform size and regular shape. The precise ratio of wall material to core material is even more crucial, ensuring the mechanical strength of the microcapsules while preventing the timely release of the repair agent due to an excessively thick wall, and preventing premature leakage of the core material during processing due to an excessively thin wall. This optimized formulation system collectively guarantees the stability of the microcapsules during storage and mixing, as well as the high efficiency of their repair function when cracked under stress, thus providing the material with reliable and durable intelligent self-healing capabilities.
[0017] Optionally, the preparation of the modified chopped steel fibers includes the following steps: S1: Short steel fibers with a length of 10–15 mm and a diameter of 0.15–0.3 mm are degreased, pickled and activated, and then chemically plated with copper to a thickness of 0.5–2 μm. S2: Epoxy resin microspheres are dispersed in an organic solvent, a silane coupling agent is added, and ultrasonic dispersion is performed to form a uniform suspension; S3: The copper-plated chopped steel fibers are immersed in the suspension, stirred at 30–50 °C for 10–20 min, and then dried at 60–80 °C for 2–4 h to obtain modified chopped steel fibers.
[0018] By employing the above technical solution, firstly, the copper plating layer provides an excellent adhesion substrate for subsequent coatings; then, utilizing the bridging effect of a silane coupling agent in an organic solvent, one end of the coupling agent is chemically bonded to the copper plating layer, while the other end is tightly bound to the epoxy resin microspheres, thereby significantly improving the adhesion strength and distribution uniformity of the microcapsules on the fiber surface; the gentle impregnation and drying process avoids damage to the microcapsule structure, ultimately constructing a robust functional coating rich in self-healing microcapsules on the surface of each fiber. This structure allows the fiber to not only act as a physical reinforcement in the matrix but also become a distributed intelligent repair unit, capable of targeted release of repair agents when micro-damage occurs at the interface, achieving in-situ reinforcement and self-healing of the fiber-matrix interface.
[0019] Optionally, the rheology modifier includes 0.3-0.5 parts of polycarboxylate superplasticizer and 0.05-1 parts of hydroxypropyl methylcellulose.
[0020] By adopting the above technical solution, the composite rheology modifier achieves precise control of the rheological behavior of the slurry on both temporal and spatial scales through the synergistic effect of the two components. The polycarboxylate-based high-efficiency water-reducing agent mainly provides a strong steric hindrance effect and electrostatic repulsion, which can effectively disperse cementitious particles and greatly reduce the amount of mixing water, thereby giving the fluidized solidified soil excellent high fluidity and self-compacting properties. Hydroxypropyl methylcellulose, as a water-soluble polymer, can extend its molecular chains in water and form a three-dimensional hydration network structure. This structure not only significantly improves the plastic viscosity and water retention of the slurry, effectively preventing segregation and bleeding, but also gives the material significant thixotropy, which enhances its fluidity under shear action (such as pumping and casting), and rapidly restores its viscosity in a static state to support fibers and solid particles and prevent sedimentation, thus jointly ensuring the macroscopic uniformity and microscopic stability of the material during construction and before setting.
[0021] Secondly, this application provides a method for preparing multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil, employing the following technical solution: A method for preparing multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil, comprising the following steps: (1) Dry mix the solidified soil matrix for 5-10 minutes to obtain a uniform mixture; (2) After mixing carbon nanotubes, silane coupling agent and some mixing water to form a dispersion, add rheology modifier, shear and stir for 5-10 min to form a uniform slurry; (3) Add the slurry obtained in step (2) to the mixture in step (1), stir for 2–3 min, add the modified short-cut steel fiber, and continue stirring for 3–5 min until uniform; (4) Adjust the water volume to make the slurry flowability reach 200–260 mm, thus obtaining the high-flowability crack-resistant solidified soil.
[0022] By adopting the above technical solution and employing a carefully planned feeding sequence and step-by-step mixing process, the effective functioning of each component and the final homogeneity of the system are ensured: First, the matrix material is dry-mixed, providing an initial environment for uniform distribution of all powders. A key step involves pre-dispersing carbon nanotubes and silane coupling agents efficiently in water. This process utilizes the surface modification effect of the coupling agent on the nanotubes, effectively breaking their agglomeration tendency and laying the foundation for a stable interfacial bond in the subsequent slurry. Subsequently, a rheology modifier is introduced for shear stirring, pre-constructing a stable rheological network in the aqueous phase. Finally, modified chopped steel fibers are added after the matrix mixture has been wetted. This step-by-step feeding strategy maximizes the protection of the functional coating and microsphere structure on the fiber surface from early mechanical damage, and utilizes the rheologically adjusted slurry to uniformly coat and disperse them. The entire process ensures that ideal results are achieved from nanoscale carbon nanotube reinforcement to macroscale fiber toughening, thereby preparing a homogeneous fluidized solidified soil with both high workability and high crack resistance.
[0023] In summary, this application has the following beneficial effects: 1. Because this application adopts a multi-scale fiber reinforcement system and intelligent self-healing interface design, the modified short-cut steel fibers and carbon nanotubes form a synergistic stress transfer and crack-resistant network at the micro to macro scales, and the epoxy resin microsphere coating endows the interface with dynamic self-healing ability, thus achieving the excellent effect of significantly improving the crack resistance, toughness and durability of the material while maintaining high fluidity.
[0024] 2. In this application, epoxy resin microcapsules with a core-shell structure are preferably used as the functional coating of the fiber. Since this structure can stably encapsulate the repair agent and release it in a targeted manner under the stress at the crack tip, it realizes in-situ repair and strengthening of fiber-matrix interface damage, and obtains excellent effects such as significantly enhancing interfacial adhesion performance, delaying damage evolution and improving the long-term service performance of the material. Detailed Implementation
[0025] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.
[0026] The sand was natural river sand with a fineness modulus of 2.3-2.6; the silicate cement was purchased from Shuangshi Mineral Products Processing Plant in Lingshou County (PO 42.5); and the copper plating solution was purchased from Oriental Material Protection Chemical Technology Research Institute (Xiamen) Co., Ltd., which was an alkaline copper plating solution.
[0027] Preparation Example
[0028] Preparation Example 1 An epoxy resin microsphere is prepared by the following steps: S1: Add 15kg of liquid bisphenol A type epoxy resin E-44, 2kg of diaminodiphenyl sulfone (latent curing agent) and 1kg of OP-10 (emulsifier) to 75kg of deionized water that has been heated to 45℃, stir for 10min until evenly dispersed, and then emulsify at high speed of 10000rpm for 15min to form a stable epoxy resin emulsion. S2: Add 8 kg of acetone solution of diphenylmethane diisocyanate with a solid content of 10% (wall material) to the above emulsion, heat to 60℃ and stir at 400 rpm for 4 hours, then adjust the pH of the system to 6-7 to terminate the reaction. S3: After the reaction is complete, the product is collected by vacuum filtration, washed 4 times with deionized water, and dried in a vacuum drying oven at 55°C for 18 hours to obtain powdered epoxy resin microspheres.
[0029] Preparation Example 2 An epoxy resin microsphere is prepared by the following steps: S1: Add 10kg of liquid bisphenol A type epoxy resin E-44, 3kg of diaminodiphenyl sulfone (latent curing agent) and 0.5kg of OP-10 (emulsifier) to 50kg of deionized water that has been heated to 45℃, stir for 10min until evenly dispersed, and then emulsify at high speed of 10000rpm for 15min to form a stable epoxy resin emulsion. S2: Add 5 kg of acetone solution of diphenylmethane diisocyanate with a solid content of 10% to the above emulsion (wall material), heat to 60℃ and stir at 400 rpm for 4 hours, then adjust the pH of the system to 6-7 to terminate the reaction. S3: After the reaction is complete, the product is collected by vacuum filtration, washed 4 times with deionized water, and dried in a vacuum drying oven at 55°C for 18 hours to obtain powdered epoxy resin microspheres.
[0030] Preparation Example 3 An epoxy resin microsphere is prepared by the following steps: S1: Add 20kg of liquid bisphenol A type epoxy resin E-44, 1kg of diaminodiphenyl sulfone (latent curing agent) and 1.5kg of OP-10 (emulsifier) to 100kg of deionized water that has been heated to 45℃, stir for 10min until evenly dispersed, and then emulsify at high speed of 10000rpm for 15min to form a stable epoxy resin emulsion. S2: Add 10 kg of acetone solution of diphenylmethane diisocyanate with a solid content of 10% (wall material) to the above emulsion, heat to 60℃ and stir at 400 rpm for 4 hours, then adjust the pH of the system to 6-7 to terminate the reaction. S3: After the reaction is complete, the product is collected by vacuum filtration, washed 4 times with deionized water, and dried in a vacuum drying oven at 55°C for 18 hours to obtain powdered epoxy resin microspheres.
[0031] Preparation Example 4 A modified chopped steel fiber, prepared by the following steps: S1: After surface degreasing and acid pickling activation of short steel fibers with a length of 10–15 mm and a diameter of 0.15–0.3 mm, the fibers are completely immersed in copper plating solution preheated to 45°C, mechanically stirred to react, and the plating thickness is controlled to be 0.5–2.0 μm. After removal, the fibers are rinsed with deionized water and dried at 60°C for 1 hour for later use. S2: 100g of epoxy resin microspheres prepared in Example 1 were dispersed in 3kg of acetone, and 0.4g of γ-aminopropyltriethoxysilane (silane coupling agent) was added. The mixture was ultrasonically dispersed at 300W and 30kHz for 45min to form a uniform suspension. S3: Take 5 kg of copper-plated chopped steel fibers and immerse them in the suspension. Stir and react at 40°C for 15 min, then vacuum at -0.05 MPa for 2 min and restore to normal pressure. Take out the fibers and dry them at 70°C for 3 h to obtain modified chopped steel fibers.
[0032] Preparation Example 5 A modified chopped steel fiber, which differs from the preparation example 4, includes the following steps: Step S1 is the same as in Preparation Example 4; S2: 100g of epoxy resin microspheres prepared in Example 2 were dispersed in 3kg of acetone, and 0.4g of γ-aminopropyltriethoxysilane (silane coupling agent) was added. The mixture was ultrasonically dispersed at 300W and 30kHz for 30min to form a uniform suspension. S3: Take 5 kg of copper-plated chopped steel fibers and immerse them in the suspension. Stir and react at 30°C for 20 min, then vacuum at -0.05 MPa for 2 min and restore to normal pressure. Take out the fibers and dry them at 60°C for 4 h to obtain modified chopped steel fibers.
[0033] Preparation Example 6 A modified chopped steel fiber, which differs from the preparation example 4, includes the following steps: Step S1 is the same as in Preparation Example 4; S2: 100g of epoxy resin microspheres prepared in Example 3 were dispersed in 3kg of acetone, and 0.4g of γ-aminopropyltriethoxysilane (silane coupling agent) was added. The mixture was ultrasonically dispersed at 300W and 30kHz for 60min to form a uniform suspension. S3: Take 5 kg of copper-plated chopped steel fibers and immerse them in the suspension. Stir and react at 50°C for 10 min, then vacuum at -0.05 MPa for 2 min and restore to normal pressure. Take out the fibers and dry them at 80°C for 2 h to obtain modified chopped steel fibers.
[0034] Preparation Example 7 A modified chopped steel fiber, which differs from the preparation example 4, includes the following steps: S1: 100g of epoxy resin microspheres prepared in Example 3 were dispersed in 3kg of acetone, and 0.4g of γ-aminopropyltriethoxysilane (silane coupling agent) was added. The mixture was ultrasonically dispersed at 300W and 30kHz for 60min to form a uniform suspension. S2: Take 5 kg of chopped steel fibers and immerse them in the suspension. Stir and react at 50°C for 10 min. Then, apply vacuum at -0.05 MPa for 2 min and restore normal pressure. Take out the fibers and dry them at 80°C for 2 h to obtain modified chopped steel fibers.
[0035] Example
[0036] Example 1
[0037] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil is prepared by the following steps: (1) Dry mix 80kg of sand and 20kg of silicate cement (cementing material) at 60rpm for 5-10min to obtain a uniform mixture; (2) Add 0.1 kg of carbon nanotubes and 0.02 kg of γ-aminopropyltriethoxysilane (silane coupling agent) to 5 kg of water and ultrasonically disperse for 15 min to prepare a dispersion. Then add 0.45 kg of rheology modifier and shear and stir at 4000 rpm for 5-10 min to form a uniform slurry. (3) Add the uniform slurry obtained in step (2) to the mixture in step (1), stir at low speed of 60 rpm for 2–3 min, add 2 kg of the modified short-cut steel fiber prepared in Preparation Example 4 and continue stirring for 3–5 min until uniform, finally add the remaining 15 kg of water, and continue stirring for 4 min until all components are mixed uniformly to obtain the high-flowability crack-resistant solidified soil; the rheology modifier includes 0.4 kg of polycarboxylate-based high-efficiency water-reducing agent and 0.05 kg of hydroxypropyl methylcellulose.
[0038] Example 2
[0039] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil is prepared by the following steps: (1) Dry mix 75kg of sand and 30kg of silicate cement (cementing material) at 60rpm for 5-10min to obtain a uniform mixture; (2) Add 0.05 kg of carbon nanotubes and 0.03 kg of γ-aminopropyltriethoxysilane (silane coupling agent) to 5 kg of water and ultrasonically disperse for 15 min to prepare a dispersion. Then add 0.6 kg of rheology modifier and shear and stir at 4000 rpm for 5-10 min to form a uniform slurry. (3) Add the uniform slurry obtained in step (2) to the mixture in step (1), stir at low speed of 60 rpm for 2–3 min, add 1 kg of the modified short-cut steel fiber prepared in Preparation Example 4 and continue stirring for 3–5 min until uniform, finally add the remaining 10 kg of water and continue stirring for 4 min until all components are mixed uniformly to obtain the high-flowability crack-resistant solidified soil; the rheology modifier includes 0.5 kg of polycarboxylate-based high-efficiency water-reducing agent and 0.1 kg of hydroxypropyl methylcellulose.
[0040] Example 3
[0041] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil is prepared by the following steps: (1) Dry mix 85kg of sand and 10kg of silicate cement (cementing material) at 60rpm for 5-10min to obtain a uniform mixture; (2) Add 0.15 kg of carbon nanotubes and 0.04 kg of γ-aminopropyltriethoxysilane (silane coupling agent) to 5 kg of water and ultrasonically disperse for 15 min to prepare a dispersion. Then add 0.35 kg of rheology modifier and shear and stir at 4000 rpm for 5-10 min to form a uniform slurry. (3) Add the uniform slurry obtained in step (2) to the mixture in step (1), stir at low speed of 60 rpm for 2–3 min, add 3 kg of the modified short-cut steel fiber prepared in Preparation Example 4 and continue stirring for 3–5 min until uniform, finally add the remaining 20 kg of water and continue stirring for 4 min until all components are mixed uniformly to obtain the high-flowability crack-resistant solidified soil; the rheology modifier includes 0.3 kg of polycarboxylate-based high-efficiency water-reducing agent and 0.05 kg of hydroxypropyl methylcellulose.
[0042] Example 4
[0043] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil differs from Example 1 in that the modified short-cut steel fibers prepared in Preparation Example 5 are used in this example.
[0044] Example 5
[0045] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil differs from Example 1 in that the modified short-cut steel fibers prepared in Preparation Example 6 are used in this example.
[0046] Example 6
[0047] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil differs from Example 1 in that the modified short-cut steel fibers prepared in Preparation Example 7 are used in this example.
[0048] Example 7
[0049] A multi-scale fiber-reinforced, highly fluid, crack-resistant solidified soil differs from Example 1 in that the rheology modifier added in this example is a polycarboxylate-based high-efficiency water-reducing agent.
[0050] Example 8
[0051] A multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil differs from Example 1 in that the rheology modifier added in this example is hydroxypropyl methylcellulose.
[0052] Comparative Example
[0053] Comparative Example 1 A multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil differs from Example 1 in that unmodified chopped steel fibers are used in this comparative example.
[0054] Performance testing Detection methods / test methods
[0055] Durability: The shrinkage rate of solidified soil (sample size 100mm×100mm×515mm) after 28 days was tested according to the relevant methods in GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". Early cracking area: The total cracking area of the solidified soil was tested according to the relevant methods in GB / T 50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". Bending toughness index: The bending toughness index was tested according to the method shown in JG / T 472-2015 "Steel Fiber Reinforced Concrete". 28-day flexural strength: The flexural and compressive strength of solidified soil (sample size 100mm×100mm×400mm) were tested according to the relevant methods in GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". Self-healing efficiency: Prepare beam specimens, preload them until microcracks appear, reaching 70% of the peak load, record the bearing capacity at this time, cure the cracked specimens under standard conditions for a certain period of 28 days, and then conduct a bending test again to calculate its self-healing efficiency.
[0056] Table 1 Test Results
[0057] Combining Examples 1-3 and Comparative Example 1 with Table 1, it can be seen that the experimental data of Examples 1-3 are all better than those of Comparative Example 1. This indicates that the epoxy resin microsphere coating can not only significantly enhance the interfacial adhesion between the fiber and the matrix through physical anchoring and stress transfer effects, thereby improving macroscopic mechanical properties and toughness, but its self-healing components can also be activated when microcracks appear, repairing interfacial damage and effectively inhibiting crack propagation.
[0058] As can be seen from Examples 1-6 and Table 1, the experimental data of Examples 1-5 are all better than those of Example 6. This indicates that the copper plating pretreatment on the surface of the chopped steel fiber is an important step to ensure the strong adhesion of the functional coating and to achieve the best effect. As a transition layer, copper plating effectively enhances the bonding force between the epoxy resin microsphere coating and the steel fiber matrix, forming a strong and tough interface transition zone, thereby achieving a better reinforcement effect.
[0059] Combining Examples 1 and 7-8 with Table 1, it can be seen that the experimental data of Example 1 are all superior to those of Examples 7-8, indicating that the rheology modifier system using polycarboxylate superplasticizer and hydroxypropyl methylcellulose has a significant synergistic effect. Only by combining the two can the slurry be endowed with excellent stability, water retention and thixotropy while ensuring high fluidity, thereby ensuring uniform fiber dispersion and ultimately obtaining the best comprehensive performance.
[0060] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil, characterized in that, Including the following parts by weight of raw materials: The mixture comprises 75-85 parts sand, 10-30 parts cementitious material, 1-3 parts modified chopped steel fiber, 0.05-0.15 parts carbon nanotubes, 0.02-0.04 parts silane coupling agent, 0.35-0.6 parts rheology modifier, and 15-25 parts water; wherein the modified chopped steel fiber is surface modified and its surface is coated with a coating containing epoxy resin microspheres.
2. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 1, characterized in that, The surface modification method of the chopped steel fiber is as follows: first, the fiber is copper-plated, and then coated with the coating containing epoxy resin microspheres, wherein the particle size of the epoxy resin microspheres is 3-8 μm.
3. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 2, characterized in that: The epoxy resin microspheres are core-shell structured microcapsules, with the core material being a mixture of liquid epoxy resin and a latent curing agent, and the wall material being any one of polyurethane.
4. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 1, characterized in that, The preparation of the epoxy resin microspheres includes the following steps: S1: Liquid epoxy resin, latent curing agent and emulsifier are added to deionized water and emulsified under high-speed shearing to form a stable epoxy resin emulsion. S2: Add wall material to the emulsion, heat and stir to react, adjust the pH of the system to 6-7, and carry out the polymerization reaction at a constant temperature so that the wall material is deposited on the surface of the epoxy resin droplets and forms a coating; S3: After the reaction is complete, the product is filtered, washed, and dried to obtain powdered epoxy resin microspheres.
5. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 1, characterized in that: The epoxy resin microspheres comprise 10-20 parts of liquid epoxy resin, 1-3 parts of latent curing agent, 0.5-1.5 parts of emulsifier, 50-100 parts of deionized water, and 5-10 parts of wall material.
6. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 1, characterized in that, The preparation of the modified chopped steel fibers includes the following steps: S1: Short steel fibers with a length of 10–15 mm and a diameter of 0.15–0.3 mm are degreased, pickled and activated, and then chemically plated with copper to a thickness of 0.5–2 μm. S2: Epoxy resin microspheres are dispersed in an organic solvent, a silane coupling agent is added, and ultrasonic dispersion is performed to form a uniform suspension; S3: The copper-plated chopped steel fibers are immersed in the suspension, stirred at 30–50 °C for 10–20 min, and then dried at 60–80 °C for 2–4 h to obtain modified chopped steel fibers.
7. The multi-scale fiber-reinforced, high-flowability, crack-resistant solidified soil according to claim 1, characterized in that: The rheology modifier includes 0.3-0.5 parts of polycarboxylate superplasticizer and 0.05-1 parts of hydroxypropyl methylcellulose.
8. A method for preparing multi-scale fiber-reinforced high-flowability crack-resistant solidified soil according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Dry mix the solidified soil matrix for 5-10 minutes to obtain a uniform mixture; (2) After mixing carbon nanotubes, silane coupling agent and some mixing water to form a dispersion, add rheology modifier, shear and stir for 5-10 min to form a uniform slurry; (3) Add the slurry obtained in step (2) to the mixture in step (1), stir for 2–3 min, add the modified short-cut steel fiber, and continue stirring for 3–5 min until uniform; (4) Adjust the water volume to make the slurry flowability reach 200–260 mm, thus obtaining the high-flowability crack-resistant solidified soil.