A composite nano calcium carbonate saline soil solidifying agent and preparation method thereof

Abstract

The present invention relates to the technical field of alloy materials, and discloses a composite nano-calcium carbonate saline soil curing agent and a preparation method thereof, comprising the following and its preparation method. Cement, fly ash and nano-calcium carbonate are mixed and stirred evenly to obtain a premix; sodium carbonate and fiber are added to the premix, and stirring is continued to obtain a composite nano-calcium carbonate saline soil curing agent. The composite nano-calcium carbonate saline soil curing agent prepared by the present invention not only has high economic benefits and soil curing effect, but also has good antifreeze performance.

Description

Technical Field

[0001] The invention relates to the technical field of soil solidifying agents, and in particular to a composite nano calcium carbonate saline soil solidifying agent and a preparation method thereof. Background Art

[0002] The Northeast region is a typical seasonally frozen soil distribution area with a large area of ​​saline soil. When canal projects pass through saline soil areas, dissolution damage often occurs. This phenomenon not only causes serious collapse of the canal, but also leads to widespread soil erosion in farmland, and has an adverse impact on local building structures. As an effective solution, saline soil solidification and improvement technology improves the adverse properties of the soil by adding specific cementitious materials to the saline soil, thereby improving its stability and bearing capacity. With the continuous emergence of new materials, saline soil improvement technology has greater room for improvement. These new materials can not only improve the improvement effect, but also help reduce project costs.

[0003] At present, the most commonly used solidifying materials are mainly traditional inorganic materials, such as cement, lime, etc. Patent CN109053096 B discloses a soda saline-alkali soil anti-freezing cracking type solidifying agent, which uses cement, anhydrous sodium silicate, water reducer and basalt short fiber as main raw materials, and mixes saline soil to make a solidifying agent; Patent CN 109257988 A discloses a method for solidifying soil in agricultural irrigation areas and solidifying ridges, and uses cementitious materials through mechanical grinding and screening to make a solidifying agent and apply it to rice field stalks. The above technical scheme improves saline soil and applies it to the construction of farmland water conservancy facilities.

[0004] The Northeast region is a typical seasonally frozen soil area. It is difficult for traditional curing agents to overcome the adverse effects of freeze-thaw conditions. The traditional curing agent components commonly used are relatively expensive, and the working performance under freeze-thaw conditions is rarely considered during preparation. Most traditional curing agents lose their performance seriously under freeze-thaw conditions, and the solidified soil often needs to be extruded, which makes construction difficult and cannot meet the needs of actual projects.

[0005] Therefore, there is currently a lack of an economical and antifreeze soil solidification technology that is adaptable to complex construction conditions. Therefore, a new technical solution is urgently needed to solve the above problems. Summary of the invention

[0006] In order to overcome the above problems of the prior art, the present invention provides a composite nano calcium carbonate saline soil solidifying agent and a preparation method thereof. The composite nano calcium carbonate saline soil solidifying agent prepared by the present invention not only has high economic benefits and soil solidification effect, but also has good antifreeze performance.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0009] 76-88 parts of cement, 3-15 parts of fly ash, 1-3 parts of nano calcium carbonate, 1-3 parts of sodium silicate, and 1-2 parts of fiber.

[0010] The fly ash used in the present invention is industrial waste, which has a low cost price, can realize waste utilization, can save a large amount of cement, can improve the workability of the mixture, reduce water thermalization and thermal expansion, and react with cement to promote cement hydration, improve the strength of solidified soil, and improve the antifreeze performance. Nano calcium carbonate can accelerate the hydration process of cement, enrich the appearance structure of hydration products, and can fill pores and improve the solidification effect of soil due to its nano-scale small size effect. After the sodium silicate is hydrated, the water glass gel is formed to fill the pores between the soil particles, and the volume expands after hardening, which offsets the shrinkage caused by the evaporation of water after the soil solidification and the volume shrinkage caused by the cement hydration reaction, and the sodium silicate can activate the activity of the fly ash to maximize the performance of the material itself.

[0011] Preferably, the cement is 425# cement.

[0012] Preferably, the particle size of the nano calcium carbonate is 10nm-100nm.

[0013] Preferably, the fiber length is 3-6 mm.

[0014] Preferably, the fiber is modified basalt fiber.

[0015] Preferably, the method for preparing the modified basalt fiber comprises the following steps:

[0016] (1) Add 3-aminopropyltriethoxysilane and succinic anhydride to N,N-dimethylformamide, heat and stir to react, then add nano-alumina and water, disperse evenly by ultrasonic oscillation, then heat and stir to react, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0017] (2) adding carboxylated nano-alumina to N,N-dimethylformamide solution, dispersing it evenly by ultrasonic oscillation, then adding 3-aminopropyltriethoxysilane and dicyclohexylcarbodiimide catalyst, heating and stirring to react, centrifugally separating, washing and drying to obtain modified nano-alumina;

[0018] (3) Adding the modified nano-alumina to a mixed solution of ethanol and water, and then adding basalt fiber, heating and stirring the mixture for reaction, and then centrifuging, washing and drying to obtain the modified basalt fiber.

[0019] Preferably, in step (1), the mass ratio of 3-aminopropyltriethoxysilane to succinic anhydride is 1:1-3.

[0020] In the technical solution of the present invention, by adding modified basalt fiber to the curing agent, a reinforcement effect is achieved between the various materials, and the frost crack resistance of the soil is significantly improved after solidification. The modified basalt fiber used in the technical solution of the present invention is different from ordinary basalt fiber. The present invention first prepares carboxylated nano-alumina, and then uses the carboxyl groups loaded on the surface of the carboxylated nano-alumina to undergo an acylation reaction with the amino groups on 3-aminopropyltriethoxysilane, thereby grafting 3-aminopropyltriethoxysilane to the surface of the nano-alumina, and then uses the hydroxyl groups generated by the hydrolysis of 3-aminopropyltriethoxysilane to undergo a dehydration condensation reaction with the hydroxyl groups on the basalt fiber, thereby combining the nano-alumina with the surface of the basalt fiber through chemical bonds, changing the morphological structure of the basalt surface, increasing the friction force between it and other materials, so that the various materials have a good reinforcement effect, and the soil has excellent antifreeze performance.

[0021] Preferably, in step (2), the mass ratio of carboxylated nano-alumina to 3-aminopropyltriethoxysilane is 1:0.3-0.8.

[0022] Preferably, in step (3), the mass ratio of basalt fiber to modified nano-alumina is 1:0.2-0.6.

[0023] Preferably, the nano calcium carbonate is subjected to a modification treatment, comprising the following steps:

[0024] Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of ethanol and water, heat and stir to hydrolyze, then add nano calcium carbonate, heat and stir to react, filter and separate, wash and dry to obtain the product.

[0025] In the technical solution of the present invention, as mentioned above, the present invention can achieve the filling of material pores and improve the solidification effect of the soil through the small size effect of calcium carbonate at the nano level, but the present invention team unexpectedly found that when nano calcium carbonate is mixed with modified basalt, a large amount of nano calcium carbonate is coated on the surface of the modified basalt, resulting in the weakening of the pore filling effect of the nano calcium carbonate material and the reduction of the solidification effect of the soil. This is unexpected by the present invention team. This may be because the surface of the modified basalt fiber is loaded with nano alumina, and there is a hydrogen bond attraction between the nano calcium carbonate and the modified basalt fiber. In order to solve the above problems, the present invention performs organic modification on the surface of the nano calcium carbonate to solve the problem of nano calcium carbonate coating on the surface of the modified basalt fiber, thereby improving the solidification effect of the soil.

[0026] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0027] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0028] Add sodium silicate and fiber into the premix and continue stirring to obtain a composite nano calcium carbonate saline soil solidifying agent.

[0029] The present invention has the following beneficial effects:

[0030] (1) Fly ash is an industrial waste with a low cost, which can realize waste utilization and significantly reduce the cost of curing agent; (2) Nano-scale calcium carbonate can accelerate the hydration process of cement and enrich the appearance structure of the hydration product. Due to its small size effect at the nano level, it can fill pores, refine the mixture, and improve the curing effect of the soil; (3) By adding modified basalt fiber to the curing agent, the materials can be reinforced to achieve a reinforcement effect, so that the frost cracking resistance of the soil is significantly improved after curing. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0032] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0033] The cement used in the specific embodiment is 425# cement, the particle size distribution of nano calcium carbonate is 10-100nm, and the length of modified basalt fiber is 3-6mm.

[0034] Example 1

[0035] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0036] 86 parts of cement, 13 parts of fly ash, 2 parts of nano calcium carbonate, 2 parts of sodium carbonate, and 1.5 parts of modified basalt fiber.

[0037] The preparation method of modified basalt fiber comprises the following steps:

[0038] (1) Add 1 g of 3-aminopropyltriethoxysilane and 2 g of succinic anhydride to 150 mL of N,N-dimethylformamide, heat to 85 °C and stir for 2 h, then add 3 g of nano-alumina and 20 mL of water, disperse evenly by ultrasonic oscillation, then heat to 50 °C and stir for 3 h, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0039] (2) Add 1 g of carboxylated nano-alumina to 50 mL of N,N-dimethylformamide solution, disperse it evenly by ultrasonic oscillation, then add 0.7 g of 3-aminopropyltriethoxysilane and 0.01 g of dicyclohexylcarbodiimide catalyst, heat to 45 °C and stir for 5 h, centrifuge, wash and dry to obtain modified nano-alumina;

[0040] (3) Add 2 g of modified nano-alumina to a mixed solution of 60 mL of ethanol and 10 mL of water, and then add basalt fiber. The mass ratio of basalt fiber to modified nano-alumina is 1:0.5. Heat to 50 °C and stir for 2 h. After centrifugal separation, washing and drying, the modified basalt fiber is obtained.

[0041] Nano calcium carbonate is modified by the following steps:

[0042] Add 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of 120 mL of ethanol and 10 mL of water, heat to 50°C, stir and hydrolyze, then add 5 g of nano calcium carbonate, heat to 60°C and stir to react for 5 hours, filter, separate, wash and dry to obtain the product.

[0043] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0044] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0045] Add sodium silicate and fiber to the premix, continue to stir and mix evenly, and obtain a composite nano calcium carbonate saline soil solidifying agent.

[0046] Example 2

[0047] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0048] 78 parts of cement, 5 parts of fly ash, 2 parts of nano calcium carbonate, 2 parts of sodium carbonate, and 1.5 parts of modified basalt fiber.

[0049] The preparation method of modified basalt fiber comprises the following steps:

[0050] (1) Add 1 g of 3-aminopropyltriethoxysilane and 2 g of succinic anhydride to 150 mL of N,N-dimethylformamide, heat to 85 °C and stir for 2 h, then add 3 g of nano-alumina and 20 mL of water, disperse evenly by ultrasonic oscillation, then heat to 50 °C and stir for 3 h, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0051] (2) Add 1 g of carboxylated nano-alumina to 50 mL of N,N-dimethylformamide solution, disperse evenly by ultrasonic oscillation, then add 0.4 g of 3-aminopropyltriethoxysilane and 0.01 g of dicyclohexylcarbodiimide catalyst, heat to 45 °C and stir for 5 h, centrifuge, wash and dry to obtain modified nano-alumina;

[0052] (3) Add 2 g of modified nano-alumina to a mixed solution of 60 mL of ethanol and 10 mL of water, and then add basalt fiber. The mass ratio of basalt fiber to modified nano-alumina is 1:0.3. Heat to 50 °C and stir for 2 h. After centrifugal separation, washing and drying, the modified basalt fiber is obtained.

[0053] Nano calcium carbonate is modified by the following steps:

[0054] Add 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of 120 mL of ethanol and 10 mL of water, heat to 50°C, stir and hydrolyze, then add 5 g of nano calcium carbonate, heat to 60°C and stir to react for 5 hours, filter, separate, wash and dry to obtain the product.

[0055] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0056] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0057] Add sodium silicate and fiber to the premix, continue to stir and mix evenly, and obtain a composite nano calcium carbonate saline soil solidifying agent.

[0058] Example 3

[0059] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0060] 80 parts of cement, 8 parts of fly ash, 2 parts of nano calcium carbonate, 2 parts of sodium carbonate, and 1.5 parts of modified basalt fiber.

[0061] The preparation method of modified basalt fiber comprises the following steps:

[0062] (1) Add 1 g of 3-aminopropyltriethoxysilane and 2 g of succinic anhydride to 150 mL of N,N-dimethylformamide, heat to 85 °C and stir for 2 h, then add 3 g of nano-alumina and 20 mL of water, disperse evenly by ultrasonic oscillation, then heat to 50 °C and stir for 3 h, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0063] (2) Add 1 g of carboxylated nano-alumina to 50 mL of N,N-dimethylformamide solution, disperse evenly by ultrasonic oscillation, then add 0.5 g of 3-aminopropyltriethoxysilane and 0.01 g of dicyclohexylcarbodiimide catalyst, heat to 45 °C and stir for 5 h, centrifuge, wash and dry to obtain modified nano-alumina;

[0064] (3) Add 2 g of modified nano-alumina to a mixed solution of 60 mL of ethanol and 10 mL of water, and then add basalt fiber. The mass ratio of basalt fiber to modified nano-alumina is 1:0.4. Heat to 50 °C and stir for 2 h. After centrifugal separation, washing and drying, the modified basalt fiber is obtained.

[0065] Nano calcium carbonate is modified by the following steps:

[0066] Add 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of 120 mL of ethanol and 10 mL of water, heat to 50°C, stir and hydrolyze, then add 5 g of nano calcium carbonate, heat to 60°C and stir to react for 5 hours, filter, separate, wash and dry to obtain the product.

[0067] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0068] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0069] Add sodium silicate and fiber to the premix, continue to stir and mix evenly, and obtain a composite nano calcium carbonate saline soil solidifying agent.

[0070] Example 4

[0071] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0072] 88 parts of cement, 15 parts of fly ash, 3 parts of nano calcium carbonate, 3 parts of sodium carbonate, and 2 parts of modified basalt fiber.

[0073] The preparation method of modified basalt fiber comprises the following steps:

[0074] (1) Add 1 g of 3-aminopropyltriethoxysilane and 3 g of succinic anhydride to 150 mL of N,N-dimethylformamide, heat to 85 °C and stir for 2 h, then add 3 g of nano-alumina and 20 mL of water, disperse evenly by ultrasonic oscillation, then heat to 50 °C and stir for 3 h, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0075] (2) Add 1 g of carboxylated nano-alumina to 50 mL of N,N-dimethylformamide solution, disperse evenly by ultrasonic oscillation, then add 0.8 g of 3-aminopropyltriethoxysilane and 0.01 g of dicyclohexylcarbodiimide catalyst, heat to 45 °C and stir for 5 h, centrifuge, wash and dry to obtain modified nano-alumina;

[0076] (3) Add 2 g of modified nano-alumina to a mixed solution of 60 mL of ethanol and 10 mL of water, and then add basalt fiber. The mass ratio of basalt fiber to modified nano-alumina is 1:0.6. Heat to 50 °C and stir for 2 h. After centrifugal separation, washing and drying, the modified basalt fiber is obtained.

[0077] Nano calcium carbonate is modified by the following steps:

[0078] Add 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of 120 mL of ethanol and 10 mL of water, heat to 50°C, stir and hydrolyze, then add 5 g of nano calcium carbonate, heat to 60°C and stir to react for 5 hours, filter, separate, wash and dry to obtain the product.

[0079] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0080] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0081] Add sodium silicate and fiber to the premix, continue to stir and mix evenly, and obtain a composite nano calcium carbonate saline soil solidifying agent.

[0082] Example 5

[0083] A composite nano calcium carbonate saline soil solidifying agent comprises the following components in parts by weight:

[0084] 76 parts of cement, 3 parts of fly ash, 1 part of nano calcium carbonate, 1 part of sodium carbonate, and 1 part of modified basalt fiber.

[0085] The preparation method of modified basalt fiber comprises the following steps:

[0086] (1) Add 1 g of 3-aminopropyltriethoxysilane and 1 g of succinic anhydride to 150 mL of N,N-dimethylformamide, heat to 85 °C and stir for 2 h, then add 3 g of nano-alumina and 20 mL of water, disperse evenly by ultrasonic oscillation, then heat to 50 °C and stir for 3 h, centrifuge, wash and dry to obtain carboxylated nano-alumina;

[0087] (2) Add 1 g of carboxylated nano-alumina into 50 mL of N,N-dimethylformamide solution, disperse evenly by ultrasonic oscillation, then add 0.3 g of 3-aminopropyltriethoxysilane and 0.01 g of dicyclohexylcarbodiimide catalyst, heat to 45 °C and stir for 5 h, centrifuge, wash and dry to obtain modified nano-alumina;

[0088] (3) Add 2 g of modified nano-alumina to a mixed solution of 60 mL of ethanol and 10 mL of water, and then add basalt fiber. The mass ratio of basalt fiber to modified nano-alumina is 1:0.2. Heat to 50 °C and stir for 2 h. After centrifugal separation, washing and drying, the modified basalt fiber is obtained.

[0089] Nano calcium carbonate is modified by the following steps:

[0090] Add 2 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of 120 mL of ethanol and 10 mL of water, heat to 50°C, stir and hydrolyze, then add 5 g of nano calcium carbonate, heat to 60°C and stir to react for 5 hours, filter, separate, wash and dry to obtain the product.

[0091] A method for preparing a composite nano calcium carbonate saline soil solidifying agent comprises the following steps:

[0092] Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix;

[0093] Add sodium silicate and fiber to the premix, continue to stir and mix evenly, and obtain a composite nano calcium carbonate saline soil solidifying agent.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that:

[0096] No modified basalt fiber is added to the curing agent.

[0097] The remaining steps are the same as those in Example 1.

[0098] Comparative Example 2

[0099] The difference between Comparative Example 2 and Example 1 is:

[0100] Replace the modified basalt fiber with ordinary basalt fiber on the market.

[0101] The remaining steps are the same as those in Example 1.

[0102] Comparative Example 3

[0103] The difference between Comparative Example 3 and Example 1 is that:

[0104] Nano calcium carbonate is not modified.

[0105] The remaining steps are the same as those in Example 1.

[0106] Performance Testing

[0107] 1. Soil solidification performance:

[0108] The curing agent prepared in the embodiment and the comparative example was mixed into the soil at a mass ratio of 1:2, and then the cured soil sample was compacted, and the compaction degree at 3d age reached more than 90%. The compressive strength was tested according to the unconfined compressive strength test method in the "Cement Soil Mix Design Code" (JGJ_T 233-2011).

[0109] 2. Antifreeze performance:

[0110] The curing agent prepared in the embodiment and the comparative example was mixed into the soil at a mass ratio of 1:2, and then the cured soil sample was compacted, and the compaction degree at the age of 3 days reached more than 90%. The freeze-thaw cycle test was carried out by the slow freezing method, and the thaw cycle test was carried out 7 times. Then, the compressive strength of the soil sample was tested, and the percentage of compressive strength decrease was calculated.

[0111] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Compressive strength (MPa) 6.5 6.2 6.3 6.7 6.0 1.7 2.3 4.5 Strength reduction percentage (%) 1.2 1.5 1.3 0.8 1.6 1.4 1.3 22.3%

[0112] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A composite nano calcium carbonate saline soil solidifier, characterized in that: It comprises the following components by weight: 76-88 parts of cement, 3-15 parts of fly ash, 1-3 parts of nano calcium carbonate, 1-3 parts of sodium silicate, 1-2 parts of fiber; The fiber is modified basalt fiber, and the preparation method of the modified basalt fiber comprises the following steps: (1) Add 3-aminopropyltriethoxysilane and succinic anhydride to N,N-dimethylformamide, heat and stir to react, then add nano-alumina and water, disperse evenly by ultrasonic oscillation, then heat and stir to react, centrifuge, wash and dry to obtain carboxylated nano-alumina; (2) adding carboxylated nano-alumina to N,N-dimethylformamide solution, dispersing it evenly by ultrasonic oscillation, then adding 3-aminopropyltriethoxysilane and dicyclohexylcarbodiimide catalyst, heating and stirring to react, centrifugally separating, washing and drying to obtain modified nano-alumina; (3) adding the modified nano-alumina into a mixed solution of ethanol and water, then adding basalt fiber, heating and stirring to react, centrifuging, washing and drying to obtain the modified basalt fiber; The nano calcium carbonate is subjected to a modification process, comprising the following steps: Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane to a mixed solution of ethanol and water, heat and stir to hydrolyze, then add nano calcium carbonate, heat and stir to react, filter and separate, wash and dry to obtain the product.

2. The composite nano calcium carbonate saline soil curing agent according to claim 1, characterized in that: The cement is 425# cement.

3. The composite nano calcium carbonate saline soil curing agent according to claim 1, characterized in that: The particle size of the nano calcium carbonate is 10nm-100nm.

4. The composite nano calcium carbonate saline soil curing agent according to claim 1, characterized in that: In the step (1), the mass ratio of 3-aminopropyltriethoxysilane to succinic anhydride is 1:1-3.

5. The composite nano calcium carbonate saline soil curing agent according to claim 1, characterized in that: In the step (2), the mass ratio of carboxylated nano-alumina to 3-aminopropyltriethoxysilane is 1:0.3-0.

8.

6. The composite nano calcium carbonate saline soil curing agent according to claim 1, characterized in that: In the step (3), the mass ratio of basalt fiber to modified nano-alumina is 1:0.2-0.

6.

7. A method for preparing the composite nano-calcium carbonate saline soil curing agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: Mix cement, fly ash and nano calcium carbonate, stir evenly to obtain a premix; Add sodium silicate and fiber into the premix and continue stirring to obtain a composite nano calcium carbonate saline soil solidifying agent.