Premixed high-strength fluidized solidified soil and preparation method thereof

Abstract

The present invention relates to the technical field of building materials, and specifically discloses a premixed high-strength fluidized solidified soil and a preparation method thereof. The premixed high-strength fluidized solidified soil comprises the following components, measured by mass: 15-24 parts of cement, 20-35 parts of fly ash, 30-42 parts of slag, 5-10 parts of epoxy resin-based fiber-reinforced composite material, 0.5-1 part of dispersant, 1-2 parts of water reducer, 0.3-0.5 parts of additive, and 100 parts of deionized water. Cement, fly ash, and slag are used as a composite gelling system, and the epoxy resin-based fiber-reinforced composite material, dispersant, water reducer, and deionized water are added and mixed. A staged stirring and layered pouring process is adopted to ensure uniform distribution of raw materials and densification of the structure. The premixed fluidized solidified soil made from industrial solid waste can effectively reduce costs, energy consumption, and CO2 emissions, has the characteristics of high strength and good compatibility, is easy to transport, and conforms to the development direction of environmental protection and sustainability.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a premixed high-strength fluidized solidified soil and a preparation method thereof. Background Art

[0002] Premixed fluidized soil is a new environmentally friendly building material. Primarily based on waste soil or foundation soil, it is modified by adding a curing agent and water to create a highly fluid, multifunctional building material. As a new backfill material, premixed fluidized soil boasts abundant raw material resources, self-leveling, self-compacting, and rapid curing. It also offers convenient construction, low cost, and environmental friendliness. It can be used in place of traditional fillers in applications such as roadbed reinforcement and engineering backfill, resolving issues such as the high demand for natural resources, severe dust pollution, and insufficient compaction in confined spaces.

[0003] Chinese patent application publication number CN119528500A discloses a solid waste-based premixed fluidized soil and its preparation method. The premixed fluidized soil comprises soil, water, and a curing agent. The curing agent comprises 20-40 parts fly ash, 30-47 parts slag, 6-18 parts silica fume, 10-15 parts marine silt, 1-3 parts water reducer, 1-3 parts sodium hydroxide, 1-3 parts calcium sulfoaluminate, 3-10 parts fiber reinforcement, and 1-3 parts phosphate. The premixed fluidized soil exhibits excellent crack resistance and can avoid stress concentration and excessive shrinkage. However, the premixed fluidized soil is corrosive to equipment, the marine silt is complex to handle, and the cost is high. Furthermore, the soil suffers from insufficient early strength, poor raw material dispersibility, and poor impermeability. A Chinese patent application with publication number CN118993685A discloses a fluidized solidified soil, its preparation method, and application construction method. The fluidized solidified soil comprises weathered rock soil and / or porous slag soil, and a curing agent. The curing agent comprises cement, slag powder, fly ash, silica fume, a water reducer, and water glass. Weathered rock soil or on-site porous slag soil is used as the main material of the fluidized solidified soil, and is cured with cement, slag powder, and fly ash. By using slag soil to replace part of the cement, carbon emissions are reduced, and the engineering slag soil generated in urban construction can be consumed on a large scale. The strength of the fluidized solidified soil after pouring is greater than that of concrete. However, the durability of the fluidized solidified soil is poor, the cost is high, and the dispersion of the raw materials is general, which affects the fluidity and strength uniformity of the fluidized solidified soil.

[0004] Therefore, developing a premixed fluidized solidified soil that is high in strength, durable, and easy to construct is an urgent problem to be solved. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a premixed high-strength fluidized solidified soil and a preparation method thereof, which solves the problem of the general strength of the premixed fluidized solidified soil.

[0006] In order to achieve the above object, the present invention discloses a premixed high-strength fluidized solidified soil, which comprises the following components in parts by mass:

[0007] 15-24 parts of cement, 20-35 parts of fly ash, 30-42 parts of slag, 5-10 parts of epoxy resin-based fiber-reinforced composite material, 0.5-1 part of dispersant, 1-2 parts of water reducer, 0.3-0.5 parts of additives, and 100 parts of deionized water;

[0008] The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps:

[0009] S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5-5.5, and then γ-glycidyloxypropyltrimethoxysilane is added. The mixture is heated and stirred to react. After the reaction is completed, the mixture is filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 h to obtain epoxy-modified calcium carbonate.

[0010] S2. Mix itaconic acid, acrylic acid, and deionized water, add sulfuric acid dropwise to adjust the pH to 1.5-2, heat in a nitrogen atmosphere, add 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate, and an initiator, stir and mix, and react. After the reaction is complete, filter with suction, wash with deionized water and anhydrous ethanol, and dry at 60° C. for 12 h to obtain a polypropylene fiber reinforced material;

[0011] S3. Evenly mix epoxy resin and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, stir and mix, react, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material.

[0012] Preferably, the cement consists of ordinary Portland cement and sulphoaluminate cement in a mass ratio of 5:1.

[0013] Preferably, the dispersant is hydroxypropyl methylcellulose.

[0014] Preferably, the water reducer is a polycarboxylate water reducer.

[0015] Preferably, the auxiliary agent consists of a retarder and a defoamer in a mass ratio of 1:3, wherein the retarder is sodium pyrophosphate and the defoamer is a polyether modified defoamer.

[0016] Preferably, the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane in S1 is 100:1500-1800:20-30.

[0017] Preferably, the reaction temperature in S1 is 80° C.-85° C., and the reaction time is 3 h-5 h.

[0018] Preferably, the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate, and initiator in S2 is 20-30:10-15:3000-4000:42-60:100:7-10:2.5-4.

[0019] Preferably, the reaction temperature in S2 is 75° C.-85° C., and the reaction time is 2 h-3 h.

[0020] Preferably, the initiator in S2 includes any one of azobisisobutyronitrile, ammonium persulfate, and potassium persulfate.

[0021] Preferably, the mass ratio of epoxy resin, epoxy-modified calcium carbonate, polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol in S3 is 100:3-7:5-10:60-70:1-2.

[0022] Preferably, the reaction temperature in S3 is 60° C.-70° C., and the reaction time is 2 h-3 h.

[0023] Preferably, the epoxy resin in S3 is epoxy resin E51.

[0024] A method for preparing the premixed high-strength fluidized solidified soil comprises the following steps:

[0025] Cement, fly ash and slag are dried separately, and then the dried fly ash and dried slag are ground. After the treatment is completed, they are stirred in a mixer at a stirring rate of 300r / min-400r / min and a stirring time of 5min-8min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirred for 3min-5min. Epoxy resin-based fiber reinforced composite materials are added, and stirred at a stirring rate of 200r / min-250r / min, and stirred for 5min-8min. Deionized water is added, and stirred at a stirring rate of 500r / min-600r / min, and stirred for 4min-6min. After casting, vibrating, covering and demoulding, premixed high-strength fluidized solidified soil is obtained.

[0026] Preferably, the cement, fly ash and slag are dried to a moisture content of ≤1% during the drying process, and after grinding, the specific surface area of the fly ash is ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, pouring is done in layers.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention uses γ-glycidyloxypropyltrimethoxysilane to modify nano calcium carbonate, introduces epoxy groups on the surface of nano calcium carbonate, obtains epoxy-modified calcium carbonate, and effectively avoids the agglomeration of nano calcium carbonate. Itaconic acid, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, and dodecyl acrylate are used as raw materials, and polymerization occurs under the action of an initiator to obtain a polypropylene fiber reinforced material. A large number of carboxyl groups, sulfonic acid groups and hydrophobic chain segments are introduced into the polypropylene fiber reinforced material, which can effectively improve dispersibility and prevent agglomeration. The sulfonic acid group can improve the hydrophilicity and suspension stability of the matrix, effectively prevent the filler from settling and stratification, and can also react with metal ions Ca 2+ Chelation inhibits the degradation of the cement matrix due to ion corrosion. The introduced long-chain alkyl hydrophobic segments can reduce the water absorption of the solidified soil and improve its water resistance and freeze-thaw resistance. The epoxy groups on the epoxy resin, epoxy-modified calcium carbonate and polypropylene fiber reinforcement, and methyltetrahydrophthalic anhydride undergo cross-linking reactions to obtain epoxy resin-based fiber-reinforced composite materials, which effectively enhance the chemical bonding between polypropylene fibers and epoxy resin, improve the fiber-resin interface bonding strength, and at the same time improve the mechanical anchoring with the cement matrix. Cement, fly ash, slag, epoxy resin-based fiber-reinforced composite materials, dispersants, water reducers, additives, and deionized water are mixed to obtain premixed high-strength fluidized solidified soil.

[0029] Fly ash and slag, as mineral admixtures in fluidized solidified soil, can effectively reduce costs, energy consumption, and CO2 emissions, aligning with environmentally sustainable development. The active alumina and silicates contained in fly ash can form a variety of hardening products, enhancing the compressive strength and toughness of the matrix. They also fill the gaps between aggregates to create a tighter structure, affecting the cement's setting time and hydration reaction, increasing the final strength of the solidified soil, inhibiting alkali-aggregate reactions, and improving durability. Slag, a type of solid waste, is rich in silicon and aluminum. The calcium-aluminum minerals and expansive silicates contained in slag can promote the reaction of cement in the matrix, generating hardening products that increase the matrix's strength, durability, and impermeability.

[0030] Nano-calcium carbonate is readily available, inexpensive, and harmless to living organisms, making it a filler with excellent mechanical properties. Polypropylene fibers, with their high strength and toughness, can improve the crack resistance, adhesion, and durability of solidified soils, effectively preventing cracks, resisting external impact and fatigue, and improving the durability of the matrix.

[0031] The dispersant, hydroxypropyl methylcellulose, stabilizes fiber dispersion and prevents agglomeration through steric hindrance. The polycarboxylate superplasticizer adsorbs on the surface of the cementitious particles, releasing free water and reducing viscosity, thereby enhancing fluidity and lowering the water-cement ratio. This, combined with the layered pouring process, ensures fluidity and self-compacting properties, making it suitable for complex structural construction.

[0032] The nano-calcium carbonate added in the present invention can effectively fill the pores of the cement matrix, reduce permeability, and improve interface bonding. Polypropylene fiber can be used as a skeleton material to improve crack resistance through fiber bridging and stress dispersion. The polypropylene fiber is modified, and the introduced sulfonic acid group and carboxyl group make the hydrophobic polypropylene fiber surface hydrophilic, effectively enhancing the hydrogen bond with the cement hydration product and improving the compatibility. Epoxy resin has high cross-linking density and corrosion resistance, can wrap inorganic gelling material particles such as cement and fly ash, and significantly improve the compressive strength and flexural strength of the solidified soil. Nano-calcium carbonate can improve the compressive strength of the matrix, polypropylene fiber and epoxy resin can improve the toughness of the matrix, and the three work synergistically to form a three-dimensional network, which can effectively inhibit the expansion of microcracks, improve the crack resistance of the matrix, form a bridging effect with the solidified soil matrix, inhibit the expansion of microcracks, and improve the strength and durability of the solidified soil.

[0033] In the present invention, cement, fly ash and slag are used as inorganic curing agents, and a mixture is obtained by mixing. The mixture is used as a gelling system, and epoxy resin-based fiber-reinforced composite materials, dispersants, water reducers and deionized water are added thereto, mixed, and a staged stirring and layered pouring process is adopted. The organic curing agent and the inorganic curing agent work synergistically to ensure that the raw materials are evenly distributed and the structure is densified, with good uniformity, to obtain premixed high-strength fluidized solidified soil. By adding a large amount of industrial solid waste fly ash and slag to replace cement in the premixed high-strength fluidized solidified soil, the amount of cement used is reduced, CO2 emissions and raw material costs can be reduced, it is green and environmentally friendly, and meets the needs of sustainable development. The added cement is a compound of ordinary Portland cement and sulphoaluminate cement. Sulphoaluminate cement has the characteristics of low temperature and fast hardening, can effectively shorten the demoulding cycle, improve construction efficiency, and can quickly generate calcium aluminoferrite and CSH gel to provide early strength. The tricalcium silicate contained in ordinary Portland cement can dominate the later hydration and generate CSH gel and Ca(OH)2. Drying and grinding fly ash and slag significantly enhances their reactivity. Cement, combined with the high reactivity of slag and fly ash, delivers both early strength and later durability. Stimulated by Ca(OH)2, slag and fly ash undergo a pozzolanic reaction, generating a secondary CSH gel that fills the matrix's pores and increases its density. Premixed fluidized solidified soils made from industrial solid waste offer high strength, excellent compatibility, ease of transportation, low cost, and environmental friendliness. DETAILED DESCRIPTION

[0034] To facilitate understanding of the present invention, the present invention will be described in more detail below. Preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Example

[0035] A method for preparing premixed high-strength fluidized solidified soil comprises the following steps:

[0036] According to mass, 15 parts of cement, 20 parts of fly ash, 30 parts of slag, 5 parts of epoxy resin-based fiber-reinforced composite materials, 0.5 parts of dispersant hydroxypropyl methylcellulose, 1 part of polycarboxylate water reducer, 0.3 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag were dried separately to a moisture content of ≤1%, and then the dried fly ash and the dried slag were ground. After grinding, the specific surface area of the fly ash was ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 300r / min and a stirring time of 8min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirred and mixed for 3min. Then, epoxy resin-based fiber reinforced composite materials are added, and stirred and mixed at a rate of 200r / min and stirred and mixed for 8min. Deionized water is added, and stirred and mixed at a rate of 500r / min and stirred and mixed for 6min. Layered pouring is adopted, and after pouring, molding, vibration, covering and demoulding, a premixed high-strength fluidized solidified soil is obtained.

[0037] The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps:

[0038] S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5, and then γ-glycidyloxypropyltrimethoxysilane is added, wherein the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane is 100:1500:20. The mixture is heated and stirred to react at 80° C. for 5 hours. After the reaction is completed, the mixture is filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 hours to obtain epoxy-modified calcium carbonate;

[0039] S2, itaconic acid, acrylic acid and deionized water were mixed uniformly, sulfuric acid was added dropwise to adjust the pH to 1.5, and in a nitrogen atmosphere, the temperature was raised, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile were added, wherein the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile was 20:10:3000:42:100:7:2.5, stirred and mixed, and reacted at a reaction temperature of 75 ° C and a reaction time of 3 h. After the reaction was completed, the mixture was filtered, washed with deionized water and anhydrous ethanol, and dried at 60 ° C for 12 h to obtain a polypropylene fiber reinforced material;

[0040] S3. Evenly mix epoxy resin E51 and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass ratio of epoxy resin E51, epoxy-modified calcium carbonate, polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol is 100:3:5:60:1. Stir and mix, react at 60°C for 3 hours, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material. Example

[0041] A method for preparing premixed high-strength fluidized solidified soil comprises the following steps:

[0042] According to parts by mass, 18 parts of cement, 28 parts of fly ash, 35 parts of slag, 7 parts of epoxy resin-based fiber-reinforced composite material, 0.6 parts of dispersant hydroxypropyl methylcellulose, 1.4 parts of polycarboxylate water reducer, 0.4 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag were dried separately to a moisture content of ≤1%, and then the dried fly ash and the dried slag were ground. After grinding, the specific surface area of the fly ash was ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 350r / min and a stirring time of 6min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirring and mixing are carried out for 4min. Then, epoxy resin-based fiber reinforced composite materials are added, and stirring and mixing are carried out at a rate of 220r / min and stirring and mixing are carried out for 6min. Deionized water is added, and stirring and mixing are carried out at a rate of 520r / min and stirring and mixing are carried out for 5min. Layered pouring is adopted, and after pouring, molding, vibration, covering and demoulding, a premixed high-strength fluidized solidified soil is obtained.

[0043] The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps:

[0044] S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5.2, and then γ-glycidyloxypropyltrimethoxysilane is added, wherein the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane is 100:1600:24. The mixture is heated and stirred to react at 82° C. for 4 hours. After the reaction is completed, the mixture is filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 hours to obtain epoxy-modified calcium carbonate;

[0045] S2, itaconic acid, acrylic acid and deionized water were mixed uniformly, sulfuric acid was added dropwise to adjust the pH to 1.8, and in a nitrogen atmosphere, the temperature was raised, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile were added, wherein the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile was 24:12:3500:48:100:8:3, stirred and mixed, and reacted at a reaction temperature of 80°C and a reaction time of 2.5h. After the reaction was completed, the mixture was filtered, washed with deionized water and anhydrous ethanol, and dried at 60°C for 12h to obtain a polypropylene fiber reinforced material;

[0046] S3. Evenly mix epoxy resin E51 and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass ratio of epoxy resin E51, epoxy-modified calcium carbonate, polypropylene fiber reinforcement, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol is 100:5:7:64:1.4. Stir and mix, react at 65°C for 2.5 hours, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material. Example

[0047] A method for preparing premixed high-strength fluidized solidified soil comprises the following steps:

[0048] According to parts by mass, 18 parts of cement, 28 parts of fly ash, 35 parts of slag, 7 parts of epoxy resin-based fiber-reinforced composite material, 0.6 parts of dispersant hydroxypropyl methylcellulose, 1.4 parts of polycarboxylate water reducer, 0.4 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag were dried separately to a moisture content of ≤1%, and then the dried fly ash and the dried slag were ground. After grinding, the specific surface area of the fly ash was ≥400m2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 350r / min and a stirring time of 6min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirring and mixing are carried out for 4min. Then, epoxy resin-based fiber reinforced composite materials are added, and stirring and mixing are carried out at a rate of 220r / min and stirring and mixing are carried out for 6min. Deionized water is added, and stirring and mixing are carried out at a rate of 520r / min and stirring and mixing are carried out for 5min. Layered pouring is adopted, and after pouring, molding, vibration, covering and demoulding, a premixed high-strength fluidized solidified soil is obtained.

[0049] The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps:

[0050] S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5.2, and then γ-glycidyloxypropyltrimethoxysilane is added, wherein the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane is 100:1600:28. The mixture is heated and stirred to react at 82° C. for 4 hours. After the reaction is completed, the mixture is filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 hours to obtain epoxy-modified calcium carbonate;

[0051] S2, itaconic acid, acrylic acid and deionized water were mixed, sulfuric acid was added dropwise to adjust the pH to 1.8, in a nitrogen atmosphere, the temperature was raised, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile were added, wherein the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile was 28:12:3500:55:100:9:3.5, stirred and mixed, reacted, the reaction temperature was 80 ° C, the reaction time was 2.5 h, after the reaction was completed, filtered, washed with deionized water and anhydrous ethanol, and dried at 60 ° C for 12 h to obtain a polypropylene fiber reinforced material;

[0052] S3. Evenly mix epoxy resin E51 and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass ratio of epoxy resin E51, epoxy-modified calcium carbonate, polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol is 100:6:9:68:1.6. Stir and mix, react at 65°C for 2.5 hours, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material. Example

[0053] A method for preparing premixed high-strength fluidized solidified soil comprises the following steps:

[0054] According to parts by mass, 21 parts of cement, 32 parts of fly ash, 40 parts of slag, 9 parts of epoxy resin-based fiber reinforced composite material, 0.8 parts of dispersant hydroxypropyl methylcellulose, 1.8 parts of polycarboxylate water reducer, 0.4 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag were dried separately to a moisture content of ≤1%, and then the dried fly ash and the dried slag were ground. After grinding, the specific surface area of the fly ash was ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 350r / min and a stirring time of 6min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirring and mixing are carried out for 4min. Then, epoxy resin-based fiber reinforced composite materials are added, and stirring and mixing are carried out at a rate of 220r / min and stirring and mixing are carried out for 6min. Deionized water is added, and stirring and mixing are carried out at a rate of 520r / min and stirring and mixing are carried out for 5min. Layered pouring is adopted, and after pouring, molding, vibration, covering and demoulding, a premixed high-strength fluidized solidified soil is obtained.

[0055] The preparation method of the epoxy resin-based fiber-reinforced composite material is the same as the preparation method of the epoxy resin-based fiber-reinforced composite material in Example 3. Example

[0056] A method for preparing premixed high-strength fluidized solidified soil comprises the following steps:

[0057] According to parts by mass, 24 parts of cement, 35 parts of fly ash, 42 parts of slag, 10 parts of epoxy resin-based fiber-reinforced composite materials, 1 part of dispersant hydroxypropyl methylcellulose, 2 parts of polycarboxylate water reducer, 0.5 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag were dried separately to a moisture content of ≤1%, and then the dried fly ash and the dried slag were ground. After grinding, the specific surface area of the fly ash was ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 400r / min and a stirring time of 5min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirred and mixed for 5min. Then, epoxy resin-based fiber reinforced composite materials are added, and stirred and mixed at a rate of 250r / min and stirred and mixed for 5min. Deionized water is added, and stirred and mixed at a rate of 600r / min and stirred and mixed for 4min. Layered pouring is adopted, and after pouring, molding, vibration, covering and demoulding, a premixed high-strength fluidized solidified soil is obtained.

[0058] The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps:

[0059] S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5.5, and then γ-glycidyloxypropyltrimethoxysilane is added, wherein the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane is 100:1800:30. The mixture is heated and stirred to react at 85° C. for 3 hours. After the reaction is completed, the mixture is filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 hours to obtain epoxy-modified calcium carbonate;

[0060] S2, itaconic acid, acrylic acid and deionized water were mixed, sulfuric acid was added dropwise to adjust the pH to 2, and in a nitrogen atmosphere, the temperature was raised, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile were added, wherein the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile was 30:15:4000:60:100:10:4, stirred and mixed, and reacted at a reaction temperature of 85 ° C and a reaction time of 2 h. After the reaction was completed, the mixture was filtered, washed with deionized water and anhydrous ethanol, and dried at 60 ° C for 12 h to obtain a polypropylene fiber reinforced material;

[0061] S3. Evenly mix epoxy resin E51 and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, wherein the mass ratio of epoxy resin E51, epoxy-modified calcium carbonate, polypropylene fiber reinforcement material, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol is 100:7:10:70:2. Stir and mix, react at 70°C for 2 hours, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material.

[0062] Comparative Example 1

[0063] A method for preparing premixed fluidized solidified soil comprises the following steps:

[0064] According to mass, 21 parts of cement, 32 parts of fly ash, 40 parts of slag, 7.8 parts of epoxy resin E51, 0.7 parts of polypropylene fiber reinforcement, 0.5 parts of epoxy modified calcium carbonate, 0.8 parts of dispersant hydroxypropyl methylcellulose, 1.8 parts of polycarboxylate water reducer, 0.4 parts of additives, and 100 parts of deionized water are weighed. The additives are composed of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. The cement, fly ash, and slag are dried separately to a moisture content of ≤1%. The dried fly ash and the dried slag are then ground. After grinding, the specific surface area of the fly ash is ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 350r / min and a stirring time of 6min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirring and mixing are carried out for 4min. Epoxy resin E51, polypropylene fiber reinforcement and epoxy modified calcium carbonate are added, and stirring and mixing are carried out at a rate of 220r / min and stirring and mixing are carried out for 6min. Deionized water is added, and stirring and mixing are carried out at a rate of 520r / min and stirring and mixing are carried out for 5min. Layered pouring is adopted, and premixed fluidized solidified soil is obtained through pouring, molding, vibration, covering and demoulding.

[0065] The preparation method of epoxy modified calcium carbonate comprises the following steps:

[0066] Nano-calcium carbonate was ultrasonically dispersed in acetone. After uniform dispersion, acetic acid solution was added to adjust the pH to 5.2, and then γ-glycidyloxypropyltrimethoxysilane was added, wherein the mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane was 100:1600:28. The mixture was heated and stirred to react at 82° C. for 4 hours. After the reaction was completed, the mixture was filtered while hot, washed with acetone, and vacuum dried at 60° C. for 12 hours to obtain epoxy-modified calcium carbonate.

[0067] The preparation method of the polypropylene fiber reinforced material comprises the following steps:

[0068] Itaconic acid, acrylic acid and deionized water are uniformly mixed, sulfuric acid is added dropwise to adjust the pH to 1.8, and the temperature is raised in a nitrogen atmosphere. 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile are added, wherein the mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator azobisisobutyronitrile is 28:12:3500:55:100:9:3.5, and the mixture is stirred and reacted. The reaction temperature is 80° C. and the reaction time is 2.5 h. After the reaction is completed, the mixture is filtered, washed with deionized water and anhydrous ethanol, and dried at 60° C. for 12 h to obtain a polypropylene fiber reinforced material.

[0069] Comparative Example 2

[0070] A method for preparing premixed fluidized solidified soil comprises the following steps:

[0071] According to mass, 21 parts of ordinary Portland cement, 72 parts of slag, 9 parts of epoxy resin-based fiber reinforced composite materials, 0.8 parts of dispersant hydroxypropyl methylcellulose, 1.8 parts of polycarboxylate water reducer, 0.4 parts of additives, and 100 parts of deionized water were weighed, wherein the additives consisted of a retarder sodium pyrophosphate and a defoamer polyether modified defoamer in a mass ratio of 1:3. Ordinary Portland cement and slag were dried separately to a moisture content of ≤1%, and then the dried slag was ground. After grinding, the specific surface area of the slag was ≥600m 2 / kg, after the treatment is completed, it is stirred in a blender at a rate of 350r / min and a stirring time of 6min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirred and mixed for 4min. Then, epoxy resin-based fiber reinforced composite material is added, and stirred and mixed at a rate of 220r / min and stirred and mixed for 6min. Deionized water is added, and stirred and mixed at a rate of 520r / min and stirred and mixed for 5min. Layered pouring is adopted, and premixed fluidized solidified soil is obtained through pouring, molding, vibration, covering and demoulding.

[0072] The preparation method of the epoxy resin-based fiber-reinforced composite material is the same as the preparation method of the epoxy resin-based fiber-reinforced composite material in Example 4.

[0073] The cement used in Examples 1-5 and Comparative Example 1 of the present invention consists of ordinary Portland cement and sulphoaluminate cement in a mass ratio of 5:1.

[0074] The ordinary Portland cement used in the examples and comparative examples of the present invention was purchased from Jiangnan Xiaoyetian Cement Co., Ltd., P·Ⅱ52.5 cement, density 3.17g / cm 3 , with a specific surface area of 388m2 / kg; sulphoaluminate cement was purchased from Tangshan Polar Bear Building Materials Co., Ltd., 42.5 grade, with a specific surface area of 334m 2 / kg; fly ash was purchased from the fly ash plant of Shenyang Power Plant and was grade II fly ash; slag was purchased from Ninghai County Hongji New Materials Co., Ltd. and was grade S95; nano-calcium carbonate was purchased from Guangxi Warner Technology Co., Ltd. with an average particle size of 20 nm and a purity of ≥99.99%; polypropylene fiber was purchased from Beijing Wantuming Technology Co., Ltd. with a diameter of 20 μm and a product number of 20200405; epoxy resin E51 was purchased from Sinopec with an epoxy value of 0.51 mol / 100 g; polycarboxylic acid water reducer was purchased from Shanghai Chenqi Chemical Technology Co., Ltd. and was produced under the model number CQJ-JSSQ2; other raw materials and reagents not specified were commercially available.

[0075] The premixed fluidized solidified soil prepared in Examples 1-5 and Comparative Examples 1-2 was subjected to relevant tests, as follows:

[0076] (1) Mechanical properties test: Examples 1-5 and Comparative Examples 1-2 were subjected to 7-day standard curing and 28-day standard curing, respectively. After curing, 3-day compressive strength, 28-day compressive strength, and 28-day flexural strength tests were performed. The test standards were tested in accordance with T / BGEA001-2019 "Technical Standard for Ready-Mixed Fluidized Solidified Soil Fill Engineering";

[0077] (2) Cracking performance test: Refer to JCT951-2005 "Test method for crack resistance of cement mortar" and measure the cracking age of concrete within 360 days under a constant temperature of (20±1)℃ and a constant humidity of (43±2)%.

[0078] The test results are shown in Table 1:

[0079] Table 1

[0080] Test items 7d compressive strength (MPa) 28d compressive strength (MPa) 28d flexural strength (MPa) Cracking age (d) Example 1 21.6 41.3 5.4 Uncracked Example 2 24.9 47.2 6.2 Uncracked Example 3 26.1 49.8 6.5 Uncracked Example 4 27.8 52.7 7.1 Uncracked Example 5 27.4 51.9 6.9 Uncracked Comparative Example 1 17.5 35.1 4.3 291 Comparative Example 2 20.3 40.0 5.5 347

[0081] The test results in Table 1 show that the fluidized solidified soils corresponding to Samples 1-5 of the present invention exhibit high strength, are not prone to cracking, and exhibit excellent durability, with excellent compressive and flexural strength. In Comparative Example 1, epoxy resin E51, polypropylene fiber reinforcement, and epoxy-modified calcium carbonate were used instead of epoxy resin-based fiber-reinforced composite materials. This resulted in poor dispersibility of the raw materials, increased agglomeration, and significantly reduced compatibility between the raw materials. This significantly reduced the overall performance of the matrix, significantly reduced strength, and increased cracking. In Comparative Example 2, only ordinary Portland cement was added, and slag was used instead of fly ash. This resulted in reduced overall performance, decreased strength, and cracking within 360 days.

[0082] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A premixed high-strength fluidized solidified soil, characterized by: Calculated by mass, it includes the following components: 15-24 parts of cement, 20-35 parts of fly ash, 30-42 parts of slag, 5-10 parts of epoxy resin-based fiber-reinforced composite material, 0.5-1 part of dispersant, 1-2 parts of water reducer, 0.3-0.5 parts of additives, and 100 parts of deionized water; The cement is composed of ordinary Portland cement and sulphoaluminate cement in a mass ratio of 5:1; The preparation method of the epoxy resin-based fiber-reinforced composite material comprises the following steps: S1. Ultrasonic dispersion of nano-calcium carbonate in acetone. After uniform dispersion, acetic acid solution is added to adjust the pH to 5-5.5, and then γ-glycidyloxypropyltrimethoxysilane is added. The mixture is heated and stirred to react. After the reaction is completed, the mixture is filtered, washed, and vacuum dried at 60° C. for 12 h to obtain epoxy-modified calcium carbonate. S2. Mix itaconic acid, acrylic acid, and deionized water, add sulfuric acid dropwise to adjust the pH to 1.5-2, raise the temperature in a nitrogen atmosphere, add 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate, and an initiator, stir and mix, react, and after the reaction is complete, filter, wash, and dry at 60° C. for 12 h to obtain a polypropylene fiber reinforced material; S3. Evenly mix epoxy resin and epoxy-modified calcium carbonate, then add polypropylene fiber reinforcement, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol, stir and mix, react, and after the reaction is completed, vacuum degassing to obtain an epoxy resin-based fiber-reinforced composite material.

2. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The dispersant is hydroxypropyl methylcellulose.

3. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

4. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The auxiliary agent consists of a retarder and a defoamer in a mass ratio of 1:3, wherein the retarder is sodium pyrophosphate and the defoamer is a polyether modified defoamer.

5. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The mass ratio of nano-calcium carbonate, acetone, and γ-glycidyloxypropyltrimethoxysilane in S1 is 100:1500-1800:20-30, the reaction temperature is 80° C.-85° C., and the reaction time is 3 h-5 h.

6. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The mass ratio of itaconic acid, acrylic acid, deionized water, 2-acrylamide-2-methylpropanesulfonic acid, polypropylene fiber, dodecyl acrylate and initiator in S2 is 20-30:10-15:3000-4000:42-60:100:7-10:2.5-4, the reaction temperature is 75°C-85°C, and the reaction time is 2h-3h.

7. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The initiator in S2 includes any one of azobisisobutyronitrile, ammonium persulfate, and potassium persulfate.

8. The premixed high-strength fluidized solidified soil according to claim 1, characterized in that: The mass ratio of epoxy resin, epoxy-modified calcium carbonate, polypropylene fiber reinforcement, methyltetrahydrophthalic anhydride, and 2,4,6-tris(dimethylaminomethyl)phenol in S3 is 100:3-7:5-10:60-70:1-2, the reaction temperature is 60°C-70°C, and the reaction time is 2h-3h; The epoxy resin in S3 is epoxy resin E51.

9. A method for preparing the premixed high-strength fluidized solidified soil according to any one of claims 1 to 8, characterized in that: The steps include: Cement, fly ash and slag are dried separately, and then the dried fly ash and dried slag are ground. After the treatment is completed, they are stirred in a mixer at a stirring rate of 300r / min-400r / min and a stirring time of 5min-8min. After uniform mixing, a mixture is obtained, and dispersant, water reducer and additives are added, and stirred for 3min-5min. Epoxy resin-based fiber reinforced composite materials are added, and stirred at a stirring rate of 200r / min-250r / min, and stirred for 5min-8min. Deionized water is added, and stirred at a stirring rate of 500r / min-600r / min, and stirred for 4min-6min. After casting, vibrating, covering and demoulding, premixed high-strength fluidized solidified soil is obtained.

10. The method for preparing a premixed high-strength fluidized solidified soil according to claim 9, characterized in that: The cement, fly ash and slag are dried to a moisture content of ≤1% during the drying process. After grinding, the specific surface area of the fly ash is ≥400m 2 / kg, the specific surface area of slag ≥600m 2 / kg, pouring is done in layers.