Nanometer modified low-temperature early-strength lunar soil curing agent and preparation method thereof

Abstract

The application provides a nano-modified low-temperature early-strength lunar soil solidifying agent and a preparation method thereof. The preparation method comprises the following steps: preparing a compound powder by mixing sulphoaluminate cement clinker, Portland cement clinker and gypsum; preparing an anti-freezing agent solution by mixing urea, calcium nitrate, sodium nitrite, calcium chloride, polycarboxylate superplasticizer and water; preparing three kinds of nano materials, namely, nano silicon dioxide, sea urchin-shaped nano silicon dioxide and magnetic sea urchin-shaped nano silicon dioxide; adding the three kinds of nano materials into the anti-freezing agent solution to obtain an anti-freezing early-strength agent solution; and adding the compound powder into the anti-freezing early-strength agent solution to obtain the nano-modified low-temperature early-strength lunar soil solidifying agent. The preparation method is simple, the raw materials are widely available, and the cost is low. The nano-modified low-temperature early-strength lunar soil solidifying agent prepared by the preparation method has a faster setting time and a higher early strength at low temperature, can prevent the occurrence of freezing damage, has great market potential, and has a wide engineering application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a nano-modified low-temperature early-strength lunar soil solidifying agent and a preparation method thereof. BACKGROUND

[0002] The establishment of a lunar base is a prerequisite for carrying out various activities on the moon. The surface of the moon is characterized by microgravity, near-vacuum, extreme temperature difference, and ultra-low thermal conductivity, making it unsuitable for maintaining human life. With the moon's daytime temperature reaching 127°C and the moon's nighttime temperature dropping to -183°C, the moon's surface experiences significant temperature changes. The moon's soil has a very low thermal conductivity, forming a stable temperature layer about one meter below the moon's surface, maintaining a temperature of about -20°C for a long time. In the future, the optimal choice for establishing a human activity base on the moon is likely to be in a low-temperature environment below the moon's surface. Therefore, building materials for lunar bases must be capable of withstanding low-temperature conditions.

[0003] When cement hydration is inhibited in a low-temperature environment, there is a large amount of unhydrated free water in the cement paste. When the ambient temperature reaches the freezing point, the free water phase freezes, causing about 9% volume expansion, which will cause a huge frost heaving stress. Due to the inhibition of cement hydration, the strength is low, and the ability to resist the frost heaving stress is poor, so the risk of freezing damage is greatly increased.

[0004] Currently, the methods commonly used in cold weather construction can be divided into two categories according to the principle: thermal protection and the addition of early-strength additives. The thermal protection method consumes a large amount of energy and emits a large amount of carbon dioxide, resulting in a large consumption of manpower and resources. Compared with the thermal protection method, adding early-strength additives is a relatively simple, convenient, and low-cost method. However, traditional early-strength additives have a suitable temperature range of about 20-40°C, and their early-strength effect is not good in a low-temperature environment below 20°C, especially below 0°C.

[0005] Therefore, how to provide a nano-modified low-temperature early-strength lunar soil solidifying agent that can still maintain strength in a low-temperature environment and thus avoid disasters caused by ice freezing and swelling is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0006] The present application aims to provide a nano-modified low-temperature early-strength lunar soil solidifying agent and a preparation method thereof to at least solve the above-mentioned technical problem.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of a nano-modified low-temperature early-strength lunar soil solidifying agent, which comprises the following steps:

[0008] S1, mix the sulphoaluminate cement clinker, Portland cement clinker and gypsum uniformly, and carry out grinding, sieving and drying to obtain a compound powder;

[0009] S2, add urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylate superplasticizer into water in sequence, stir uniformly to obtain an antifreeze solution;

[0010] S3, mix cetyltrimethylammonium bromide, sodium salicylate and deionized water uniformly, heat to completely dissolve to obtain a first reaction liquid; add triethylamine and tetraethyl orthosilicate into the first reaction liquid, stir uniformly, cool to room temperature to obtain a second reaction liquid; wash the second reaction liquid by anhydrous ethanol, vacuum dry at 45 DEG C and grind to obtain a first reactant; place the first reactant in an oven at 600 DEG C and keep for 4.5 h to obtain white powder nano-silica;

[0011] S4, add the nano-silica into anhydrous ethanol, ultrasonic disperse uniformly to obtain a first dispersion liquid; add 3-(isobutenoyloxy) propyl trimethoxysilane and ammonia water into the first dispersion liquid, react at room temperature for 6 h to obtain a second reactant; wash the second reactant by anhydrous ethanol, vacuum dry to obtain urchin-like nano-silica;

[0012] S5, add the nano-silica and nano-ferroferric oxide into anhydrous ethanol, ultrasonic disperse uniformly to obtain a second dispersion liquid; add 3-(isobutenoyloxy) propyl trimethoxysilane and ammonia water into the second dispersion liquid, react at room temperature for 6 h to obtain a third reactant; separate the third reactant by a strong magnetic field, wash by anhydrous ethanol, vacuum dry to obtain magnetic urchin-like nano-silica;

[0013] S6, add the nano-silica, the urchin-like nano-silica and the magnetic urchin-like nano-silica into the antifreeze solution, stir uniformly to obtain a mixed liquid; ultrasonic treat the mixed liquid to obtain an antifreezing early strength agent solution;

[0014] S7, add the compound powder into the antifreezing early strength agent solution, stir uniformly to obtain a nano-modified low-temperature early strength lunar soil curing agent.

[0015] In the first aspect, the mixing of the sulphoaluminate cement clinker, the Portland cement clinker and the gypsum is uniform, and grinding, sieving and drying are performed to obtain a compound powder, which comprises: mixing the sulphoaluminate cement clinker, the Portland cement clinker and the gypsum uniformly to obtain a mixture; pouring the mixture into a ball mill for ball grinding for 60-80 min to obtain a ground material A; pouring the ground material A into a vibrating screen for sieving through a square hole screen of 75 μm to obtain a ground material B with a particle size of less than 75 μm; and placing the ground material B in an oven with a temperature of 105 ℃ for drying to constant weight for 48-60 h to obtain the compound powder.

[0016] In the first aspect, in step S2, urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylate superplasticizer are sequentially added to water, and stirring is performed on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 10-20 min, after the stirring is completed, standing is performed for 2-4 h to obtain an antifreeze solution.

[0017] In the first aspect, in step S6, the nano-silica, the sea urchin-shaped nano-silica and the magnetic sea urchin-shaped nano-silica are added to the antifreeze solution, and stirring is performed on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 5-10 min, after the stirring is completed, a mixed solution is obtained; the mixed solution is placed in an ultrasonic cleaning instrument for ultrasonic treatment for 10-20 min to obtain an antifreeze early strength agent solution.

[0018] In the first aspect, the adding of the compound powder to the antifreeze early strength agent solution and the uniform stirring to obtain a nano-modified low-temperature early strength lunar soil curing agent specifically comprises: adding the compound powder to the antifreeze early strength agent solution to obtain a first mixture; transferring the first mixture to a neat paste mixer for stirring for 1 min to obtain a second mixture; wherein the revolution speed of the stirring blade of the neat paste mixer is 62 r / min, and the rotation speed of the stirring blade of the neat paste mixer is 140 r / min; continuing to stir the second mixture for 1 min to obtain the nano-modified low-temperature early strength lunar soil curing agent; wherein the revolution speed of the stirring blade of the neat paste mixer is 125 r / min, and the rotation speed of the stirring blade of the neat paste mixer is 285 r / min.

[0019] The second aspect of the application provides a nano-modified low-temperature early strength lunar soil curing agent, which is prepared by the preparation method of the nano-modified low-temperature early strength lunar soil curing agent according to the first aspect; the curing agent is composed of the following components in weight fractions: 60-80 parts of a compound powder and 10-30 parts of an antifreeze early strength agent solution.

[0020] In the second aspect, the compound powder is compounded by 60-80 parts of sulphoaluminate cement clinker, 5-25 parts of Portland cement clinker and 1-5 parts of gypsum; the particle size of the compound powder is less than 75 microns.

[0021] In the second aspect, the anti-freezing early strength agent solution comprises, in parts by weight, 80-120 parts of anti-freezing agent solution, 0.1-3 parts of nano-silica, 0.1-3 parts of sea urchin-shaped nano-silica and 0.1-3 parts of magnetic sea urchin-shaped nano-silica; the sea urchin-shaped nano-silica comprises, in parts by weight, 0.5-1 part of nano-silica, 10-30 parts of ethanol, 2-6 parts of 3-(isobutenoyloxy)propyl trimethoxysilane and 0.5-3 parts of ammonia; the magnetic sea urchin-shaped nano-silica comprises, in parts by weight, 0.5-1.5 parts of nano-silica, 5-35 parts of ethanol, 2-8 parts of 3-(isobutenoyloxy)propyl trimethoxysilane, 0.5-4 parts of ammonia and 0.01-1 parts of nano-ferroferric oxide.

[0022] In the second aspect, the anti-freezing agent solution comprises, in parts by weight, 5-15 parts of urea, 5-15 parts of calcium nitrate, 1-6 parts of sodium nitrite, 1-4 parts of calcium chloride and 0.5-2.5 parts of polycarboxylic acid water reducer.

[0023] In the second aspect, the nano-silica comprises, in parts by weight, 1-3 parts of hexadecyl trimethyl ammonium bromide, 0.5-1.5 parts of sodium salicylate, 0.1-1 parts of triethylamine and 10-25 parts of tetraethyl orthosilicate.

[0024] Advantages:

[0025] This invention provides a method for preparing a nano-modified low-temperature early-strength lunar soil hardener. First, a compound powder is prepared by mixing sulfoaluminate cement clinker, silicate cement clinker, and gypsum. Utilizing the high early strength and fast setting speed of sulfoaluminate cement, the addition of silicate cement prevents AFt from crystallizing and growing too rapidly during the pre-curing period, allowing them to overlap and establish a relatively loose structure, while ensuring later strength development and saving material costs. Second, urea, calcium nitrate, sodium nitrite, calcium chloride, and polycarboxylate superplasticizer are added to water sequentially and stirred evenly to obtain an antifreeze solution, which can lower the freezing point of the solution. Then, by modifying nano-silica, sea urchin-shaped nano-silica and magnetic sea urchin-shaped nano-silica are obtained. The sea urchin-shaped nano-silica particles have excellent monodispersity, uniform particle size distribution, smaller size, and larger specific surface area, enabling them to form more nucleation sites in the cement paste and reducing the formation of hydration products. The nucleation barrier and the tight interweaving of hydration products with nanoparticles enhance the strength of the curing agent. Furthermore, the growth of some hydration products on the nanoparticles thins the hydration product layer on the clinker particles, reducing the dissolution inhibition caused by the presence of this layer. Additionally, the addition of magnetic sea urchin-like nano-silica improves the reduced fluidity caused by nanomaterials. Subsequently, nano-silica, sea urchin-like nano-silica, and magnetic sea urchin-like nano-silica are added to the aforementioned antifreeze solution and mixed thoroughly to prepare an antifreeze early-strength agent solution. This eliminates the need for heat treatment of the raw materials, allowing direct mixing of raw materials stored at low outdoor temperatures, ensuring hydration of the cement paste and saving manpower and resources. Simultaneously, as hydration progresses, a network structure of hydration products is established. The reduction in the radius of curvature and pore size at the ice / water interface leads to an increase in vapor pressure, further lowering the freezing point of the pore solution and ensuring continuous cement hydration. This invention utilizes nano-modification to promote the hydration rate of the curing agent, thereby improving its early strength and preventing damage to the poorly hydrated curing agent caused by frost heave stress resulting from the freezing of free water at low temperatures. The preparation method provided by this invention is simple, uses widely available raw materials, and is low-cost. The nano-modified low-temperature early-strength lunar soil curing agent prepared using this method exhibits faster setting time and higher early strength at low temperatures, preventing frost damage. It has significant market potential and broad prospects for engineering applications.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0028] Figure 1 The flowchart of the preparation method of a nano-modified low-temperature early-strength lunar soil solidifying agent in the present application. DETAILED DESCRIPTION

[0029] The advantages and various effects of the present application will be more clearly presented by the specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, not to limit the present application.

[0030] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a conflict, the present specification takes precedence.

[0031] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or obtained by existing methods.

[0032] Please refer to Figure 1 The present application provides a preparation method of a nano-modified low-temperature early-strength lunar soil solidifying agent, which comprises the following steps:

[0033] S1, uniformly mixing sulphoaluminate cement clinker, Portland cement clinker and gypsum, and performing grinding, sieving and drying to obtain a compounded powder;

[0034] S2, adding urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylic acid water reducing agent into water in sequence, stirring uniformly to obtain an anti-freezing agent solution;

[0035] S3, uniformly mixing cetyltrimethylammonium bromide, sodium salicylate and deionized water, heating to complete dissolution to obtain a first reaction liquid; adding triethylamine and tetraethyl orthosilicate into the first reaction liquid, stirring uniformly, cooling to room temperature to obtain a second reaction liquid; washing the second reaction liquid by anhydrous ethanol, vacuum drying at 45 DEG C and grinding to obtain a first reaction product; placing the first reaction product in an oven at 600 DEG C for 4.5 h to obtain white powder nano-silicon dioxide;

[0036] S4, adding the nanosilica to anhydrous ethanol, ultrasonic dispersion is uniform, to obtain a first dispersion liquid; adding 3-(isobutenoyloxy) propyl trimethoxysilane, ammonia to the first dispersion liquid, reaction at room temperature for 6 h, to obtain a second reactant; washing the second reactant by anhydrous ethanol, vacuum drying, to obtain sea urchin-shaped nanosilica;

[0037] S5, adding the nanosilica and nanometer ferric oxide to anhydrous ethanol, ultrasonic dispersion is uniform, to obtain a second dispersion liquid; adding 3-(isobutenoyloxy) propyl trimethoxysilane, ammonia to the second dispersion liquid, reaction at room temperature for 6 h, to obtain a third reactant; separating the third reactant by a strong magnetic field, and washing with anhydrous ethanol, vacuum drying, to obtain magnetic sea urchin-shaped nanosilica;

[0038] S6, adding the nanosilica, the sea urchin-shaped nanosilica and the magnetic sea urchin-shaped nanosilica to the antifreeze solution, stirring is uniform, to obtain a mixed liquid; ultrasonic treatment of the mixed liquid, to obtain an antifreeze early strength agent solution;

[0039] S7, adding the compound powder to the antifreeze early strength agent solution, stirring is uniform, to obtain a nanometer modified low temperature early strength lunar soil curing agent.

[0040] Specifically, the application provides a preparation method of a nano-modified low-temperature early-strength lunar soil solidifying agent. First, a mixed powder is prepared by mixing and compounding sulphoaluminate cement clinker, Portland cement clinker and gypsum. The sulphoaluminate cement clinker has the characteristics of high early strength and fast setting speed. The addition of the Portland cement clinker avoids the crystallization and rapid growth of AFt during the pre-hydration period, and the mutual lapping establishes a relatively loose structure, while ensuring the development of the late strength and saving the material cost. Second, urea, calcium nitrate, sodium nitrite, calcium chloride and a polycarboxylic acid water reducing agent are sequentially added into water and stirred uniformly to obtain an anti-freezing agent solution, which can reduce the freezing point of the solution. Third, the nano-silicon dioxide is modified to obtain urchin-shaped nano-silicon dioxide and magnetic urchin-shaped nano-silicon dioxide. The urchin-shaped nano-silicon dioxide particles have good monodispersity, uniform particle size distribution, smaller size and larger specific surface area, can form more nucleation sites in the cement paste, reduce the nucleation potential barrier of the hydration product, and make the hydration product and the nano-particles closely interlaced together to improve the strength of the solidifying agent. When some hydration products grow on the nano-particles, the hydration product layer on the clinker particles becomes thin, thereby reducing the dissolution inhibition caused by the hydration product layer. Further, the addition of the magnetic urchin-shaped nano-silicon dioxide can improve the problem of reduced fluidity caused by the nano-material. Then, the urchin-shaped nano-silicon dioxide and the magnetic urchin-shaped nano-silicon dioxide are added into the anti-freezing agent solution and mixed uniformly to prepare an anti-freezing early-strength agent solution, so that the raw materials stored at low temperature outdoors can be directly mixed and stirred without heat treatment, the cement paste can be hydrated, and the manpower and resources are saved. Meanwhile, with the progress of hydration, a network structure of the hydration product is established, the decrease of the ice / water interface curvature radius and the pore size leads to the increase of the vapor pressure, and the freezing point of the pore solution is further reduced, thereby ensuring the continuous hydration of the cement. The application promotes the hydration rate of the solidifying agent by using the nano-modification method, improves the early strength of the solidifying agent, and avoids the damage of the frost heaving stress caused by the freezing of free water at low temperature to the solidifying agent with poor hydration degree. The preparation method provided by the application is simple, the raw materials are widely available, and the cost is low. The nano-modified low-temperature early-strength lunar soil solidifying agent prepared by the preparation method has a faster setting time and higher early strength at low temperature, can prevent the occurrence of frost damage, has great market potential, and has a wide engineering application prospect.

[0041] In some possible embodiments, the mixing and uniformizing of the sulphoaluminate cement clinker, the Portland cement clinker and the gypsum, and the grinding, sieving and drying of the mixed powder to obtain the mixed powder include the following steps.

[0042] S11, uniformly mixing the sulphoaluminate cement clinker, the Portland cement clinker and the gypsum to obtain a mixture; pouring the mixture into a ball mill for ball milling for 60-80 min to obtain a ground material A;

[0043] S12, pour the ground material A into a vibrating screen to pass through a square hole screen of 75 pm to obtain a ground material B with a particle size of less than 75 pm;

[0044] S13, dry the ground material B in an oven at a temperature of 105°C for 48-60 hours to constant weight to obtain the compounded powder.

[0045] This is because, after mixing the sulphoaluminate cement clinker, the Portland cement clinker and the gypsum, ball milling is performed by a ball mill to obtain the ground material A, so that the raw materials in the ground material A are fully mixed and uniformly dispersed; then sieving is performed by a square hole screen of 75 pm to obtain the ground material B with uniform particle size, which is beneficial to subsequent uniform dispersion of the anti-freezing early strength agent solution and improves the compressive strength of the solidified body; finally, the ground material B is dried in an oven at a temperature of 105°C for 48-60 hours to constant weight to remove volatile components to obtain the compounded powder.

[0046] In some possible embodiments, in step S2, urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylate superplasticizer are sequentially added to water and stirred on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 10-20 min, after stirring, the mixture is left to stand for 2-4 h to obtain the anti-freezing agent solution.

[0047] Those skilled in the art can understand that the anti-freezing agent solution prepared by taking urea, calcium nitrate, sodium nitrite and calcium chloride as the anti-freezing components and polycarboxylate superplasticizer as the water-reducing component can reduce the freezing point of water after mixing with water, so that the hydration reaction of concrete can still be carried out at negative temperature.

[0048] In some possible embodiments, in step S6, the nano-silica, the sea urchin-shaped nano-silica and the magnetic sea urchin-shaped nano-silica are added to the anti-freezing agent solution and stirred on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 5-10 min, after stirring, a mixed solution is obtained; the mixed solution is placed in an ultrasonic cleaner and ultrasonically treated for 10-20 min to obtain the anti-freezing early strength agent solution.

[0049] The skilled in the art can understand that adding the nanomaterial to the antifreeze solution can play a role of crystal nucleus in the cement hydration process and promote the cement hydration process; the urchin-like nanosilica as a typical spherical urchin-like morphology has smaller size and larger specific surface area, and can form more nucleation sites; the magnetic urchin-like nanosilica is a nanosphere in which the urchin-like nanosilica is wrapped on the surface of the ferroferric oxide nanoparticles, which can improve the surface effect of the urchin-like nanosilica, nanosilica and fluid, reduce the viscosity of the nanomaterial in the fluid, and improve the flow speed of the fluid.

[0050] In some possible embodiments, the adding the compound powder to the antifreeze early strength agent solution and stirring uniformly to obtain the nanomodified low-temperature early strength lunar soil curing agent specifically includes:

[0051] S71, adding the compound powder to the antifreeze early strength agent solution to obtain a first mixture;

[0052] S72, transferring the first mixture to a neat paste mixer and stirring for 1 min to obtain a second mixture; wherein the stirring blade revolution speed of the neat paste mixer is 62 r / min, and the stirring blade rotation speed of the neat paste mixer is 140 r / min;

[0053] S73, continuing to stir the second mixture for 1 min to obtain the nanomodified low-temperature early strength lunar soil curing agent; wherein the stirring blade revolution speed of the neat paste mixer is 125 r / min, and the stirring blade rotation speed of the neat paste mixer is 285 r / min.

[0054] This is because, after adding the compound powder to the antifreeze early strength agent, the compound powder can be prevented from flying around during the stirring process due to the small particle size of the compound powder, so that the compound powder can enter the antifreeze early strength agent solution; and the fast stirring can improve the reaction rate.

[0055] Based on the same inventive concept, the application further provides a nanomodified low-temperature early strength lunar soil curing agent, which is prepared by the preparation method of the nanomodified low-temperature early strength lunar soil curing agent according to the first aspect; the curing agent is composed of the following components in weight fraction: 60-80 parts of compound powder and 10-30 parts of antifreeze early strength agent solution.

[0056] In some possible embodiments, the compound powder is compounded by 60-80 parts of sulphoaluminate cement clinker, 5-25 parts of Portland cement clinker and 1-5 parts of gypsum; and the particle size of the compound powder is less than 75 μm.

[0057] In some possible embodiments, the anti-freezing early strength agent solution comprises, in parts by weight, 80-120 parts of an anti-freezing agent solution, 0.1-3 parts of nano-silicon dioxide, 0.1-3 parts of sea urchin-shaped nano-silicon dioxide, and 0.1-3 parts of magnetic sea urchin-shaped nano-silicon dioxide; the sea urchin-shaped nano-silicon dioxide comprises, in parts by weight, 0.5-1 part of nano-silicon dioxide, 10-30 parts of ethanol, 2-6 parts of 3-(isobutenoyloxy)propyl trimethoxysilane, and 0.5-3 parts of ammonia; and the magnetic sea urchin-shaped nano-silicon dioxide comprises, in parts by weight, 0.5-1.5 parts of nano-silicon dioxide, 5-35 parts of ethanol, 2-8 parts of 3-(isobutenoyloxy)propyl trimethoxysilane, 0.5-4 parts of ammonia, and 0.01-1 part of nano-ferroferric oxide.

[0058] In some possible embodiments, the anti-freezing agent solution comprises, in parts by weight, 5-15 parts of urea, 5-15 parts of calcium nitrate, 1-6 parts of sodium nitrite, 1-4 parts of calcium chloride, and 0.5-2.5 parts of polycarboxylate superplasticizer.

[0059] In some possible embodiments, the nano-silicon dioxide comprises, in parts by weight, 1-3 parts of cetyltrimethylammonium bromide, 0.5-1.5 parts of sodium salicylate, 0.1-1 part of triethylamine, and 10-25 parts of tetraethyl orthosilicate.

[0060] The present application is further described below in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. In the following examples, the experimental methods not specified in the specific conditions are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0061] Example 1

[0062] The present embodiment provides a nano-modified low-temperature early strength lunar soil curing agent, and the preparation method comprises the following steps:

[0063] (1) 70 parts of a sulphoaluminate cement clinker, 20 parts of a Portland cement clinker, and 3 parts of gypsum are uniformly mixed and then poured into a ball mill for ball milling for 60 min at a speed of 200 r / min to obtain a ground material A; the ground material A is poured into a vibrating screen to pass through a square hole screen with a mesh size of 75 μm to obtain a ground material B with a particle size of less than 75 μm; and the ground material B is dried in an oven at a temperature of 105 ℃ for 48 h to a constant weight to obtain a compounded powder;

[0064] (2) adding 5 parts of urea, 5 parts of calcium nitrate, 1 part of sodium nitrite, 2 parts of calcium chloride and 0.8 parts of polycarboxylate superplasticizer into water in sequence, and placing on a magnetic stirrer for stirring, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 10-20 min, after the stirring is completed, standing for 2-4 h, to obtain an antifreeze solution.

[0065] (3) mixing 1.5 parts of cetyltrimethylammonium bromide, 0.5 parts of sodium salicylate and deionized water uniformly, heating to complete dissolution, to obtain a first reaction liquid; adding 0.2 parts of triethylamine and 20 parts of tetraethyl orthosilicate into the first reaction liquid, stirring uniformly, and cooling to room temperature, to obtain a second reaction liquid; washing the second reaction liquid by anhydrous ethanol, vacuum drying at 45 ℃, and grinding, to obtain a first reaction product; placing the first reaction product in an oven at 600 ℃ for 4.5 h, to obtain white powder nano-silica;

[0066] (4) adding 0.5 parts of nano-silica into 20 parts of anhydrous ethanol, ultrasonic dispersion uniformly, to obtain a first dispersion liquid; adding 6 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 0.5 parts of ammonia water into the first dispersion liquid, reacting at room temperature for 6 h, to obtain a second reaction product; washing the second reaction product by anhydrous ethanol, vacuum drying, to obtain urchin-shaped nano-silica;

[0067] (5) adding 0.5 parts of nano-silica and 0.05 parts of nano-magnetic ferrite into 20 parts of anhydrous ethanol, ultrasonic dispersion uniformly, to obtain a second dispersion liquid; adding 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 1.5 parts of ammonia water into the second dispersion liquid, reacting at room temperature for 6 h, to obtain a third reaction product; separating the third reaction product by a strong magnetic field, washing by anhydrous ethanol, and vacuum drying, to obtain magnetic urchin-shaped nano-silica;

[0068] (6) adding 0.5 parts of nano-silica, 0.1 parts of urchin-shaped nano-silica and 0.1 parts of magnetic urchin-shaped nano-silica into 100 parts of the antifreeze solution, and placing on a magnetic stirrer for stirring, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 5-10 min, after the stirring is completed, obtaining a mixed liquid; placing the mixed liquid in an ultrasonic cleaner, ultrasonic treatment for 10-20 min, to obtain an antifreeze early strength agent solution;

[0069] (7) 60 parts of the compound powder is added into 15 parts of the anti-freezing early strength agent solution, and is transferred to a clean paste stirrer, and is stirred slowly for 1 min, the stirring blade revolution speed of the clean paste stirrer is 62 r / min, the stirring blade rotation speed of the clean paste stirrer is 140 r / min; then is stirred quickly for 1 min, the stirring blade revolution speed of the clean paste stirrer is 125 r / min, the stirring blade rotation speed of the clean paste stirrer is 285 r / min, and the nano modified low temperature early strength lunar soil curing agent is obtained.

[0070] Example 2

[0071] The nano modified low temperature early strength lunar soil curing agent provided in the embodiment, the raw material components are calculated by weight percentage, and the preparation method comprises the following steps:

[0072] (1) 75 parts of sulphoaluminate cement clinker, 15 parts of Portland cement clinker and 2 parts of gypsum are uniformly mixed, and are poured into a ball mill for ball milling for 65 min, the rotation speed of the ball mill is 200 r / min, and the ground material A is obtained; the ground material A is poured into a vibrating screen for screening through a square hole screen with a size of 75 μm, and the ground material B with a particle size of less than 75 μm is obtained; the ground material B is placed in an oven with a temperature of 105 ℃ for drying to constant weight for 52 h, and the compound powder is obtained;

[0073] (2) 6 parts of urea, 6 parts of calcium nitrate, 2 parts of sodium nitrite, 1 part of calcium chloride and 0.75 parts of polycarboxylate superplasticizer are sequentially added into water, and are stirred on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 10-20 min, after the stirring is completed, the mixture is statically placed for 2-4 h, and the anti-freezing agent solution is obtained.

[0074] (3) 1.5 parts of cetyltrimethylammonium bromide, 0.5 parts of sodium salicylate and deionized water are uniformly mixed and heated to completely dissolve, and the first reaction liquid is obtained; 0.2 parts of triethylamine and 20 parts of tetraethyl orthosilicate are added into the first reaction liquid, and are uniformly stirred, and the second reaction liquid is obtained after being cooled to room temperature; the second reaction liquid is washed by anhydrous ethanol, and is vacuum dried at 45 ℃ and ground, and the first reaction material is obtained; the first reaction material is placed in an oven for heat preservation at 600 ℃ for 4.5 h, and the white powder nano silicon dioxide is obtained;

[0075] (4) 0.5 parts of the nano silicon dioxide is added into 10 parts of anhydrous ethanol, and is uniformly ultrasonically dispersed, and the first dispersion liquid is obtained; 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 1 part of ammonia water are added into the first dispersion liquid, and are reacted at room temperature for 6 h, and the second reaction material is obtained; the second reaction material is washed by anhydrous ethanol, and is vacuum dried, and the sea urchin-shaped nano silicon dioxide is obtained;

[0076] (5) adding 1.5 parts of nano-silicon dioxide and 0.05 parts of nano-ferroferric oxide into 10 parts of anhydrous ethanol, uniformly ultrasonic dispersing to obtain a second dispersion liquid; adding 6 parts of 3-(isobutenoyloxy) propyl trimethoxysilane, 1 part of ammonia water into the second dispersion liquid, reacting at room temperature for 6 hours to obtain a third reactant; separating the third reactant by a strong magnetic field, washing with anhydrous ethanol, and vacuum drying to obtain the magnetic urchin-shaped nano-silicon dioxide;

[0077] (6) adding 1 part of nano-silicon dioxide, 0.5 part of urchin-shaped nano-silicon dioxide and 0.2 part of magnetic urchin-shaped nano-silicon dioxide into 80 parts of the antifreeze solution, and stirring on a magnetic stirrer, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 5-10 minutes, and after the stirring is completed, obtaining a mixed liquid; placing the mixed liquid in an ultrasonic cleaning instrument, and ultrasonic treating for 10-20 minutes to obtain the antifreeze early strength agent solution;

[0078] (7) adding 70 parts of the compound powder into 10 parts of the antifreeze early strength agent solution, and transferring to a clean paste stirrer, slowly stirring for 1 minute, the stirring blade revolution speed of the clean paste stirrer being 62 r / min, and the stirring blade rotation speed of the clean paste stirrer being 140 r / min; then fast stirring for 1 minute, the stirring blade revolution speed of the clean paste stirrer being 125 r / min, and the stirring blade rotation speed of the clean paste stirrer being 285 r / min, to obtain the nano-modified low-temperature early strength lunar soil curing agent.

[0079] Example 3

[0080] The nano-modified low-temperature early strength lunar soil curing agent provided in the embodiment, the raw materials are in parts by weight, and the preparation method comprises the following steps:

[0081] (1) uniformly mixing 80 parts of sulphate cement clinker, 10 parts of silicate cement clinker and 1 part of gypsum, pouring into a ball mill for ball milling for 70 minutes, the rotation speed of the ball mill being 200 r / min, to obtain a ground material A; pouring the ground material A into a vibrating screen to pass through a square hole screen with a mesh size of 75 μm to obtain a ground material B with a particle size of less than 75 μm; placing the ground material B in an oven with a temperature of 105 ℃ for drying to constant weight for 56 hours to obtain a compound powder;

[0082] (2) adding 7 parts of urea, 7 parts of calcium nitrate, 3 parts of sodium nitrite, 2 parts of calcium chloride and 1 part of polycarboxylate superplasticizer into water, and stirring on a magnetic stirrer, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 10-20 minutes, and after the stirring is completed, standing for 2-4 hours to obtain an antifreeze solution.

[0083] (3) 1.5 parts of cetyltrimethylammonium bromide, 0.5 parts of sodium salicylate and deionized water were mixed uniformly and heated to complete dissolution to obtain a first reaction liquid; 0.2 parts of triethylamine and 20 parts of tetraethyl orthosilicate were added to the first reaction liquid and stirred uniformly, and then cooled to room temperature to obtain a second reaction liquid; the second reaction liquid was washed by anhydrous ethanol, vacuum dried at 45 DEG C and ground to obtain a first reactant; the first reactant was placed in an oven at 600 DEG C and reacted for 4.5 h to obtain white powder nano-silicon dioxide;

[0084] (4) 0.8 parts of nano-silicon dioxide was added to 25 parts of anhydrous ethanol and ultrasonically dispersed uniformly to obtain a first dispersion liquid; 6 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 3 parts of ammonia water were added to the first dispersion liquid and reacted at room temperature for 6 h to obtain a second reactant; the second reactant was washed by anhydrous ethanol and vacuum dried to obtain urchin-shaped nano-silicon dioxide;

[0085] (5) 1.2 parts of nano-silicon dioxide and 0.05 parts of nano-magnetic iron oxide were added to 25 parts of anhydrous ethanol and ultrasonically dispersed uniformly to obtain a second dispersion liquid; 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 0.5 parts of ammonia water were added to the second dispersion liquid and reacted at room temperature for 6 h to obtain a third reactant; the third reactant was separated by a strong magnetic field, washed by anhydrous ethanol and vacuum dried to obtain magnetic urchin-shaped nano-silicon dioxide;

[0086] (6) 1.5 parts of nano-silicon dioxide, 1.5 parts of urchin-shaped nano-silicon dioxide and 0.2 parts of magnetic urchin-shaped nano-silicon dioxide were added to 120 parts of an antifreezing agent solution and stirred on a magnetic stirrer; the stirring speed of the magnetic stirrer was set to 2500 r / min and the stirring time was 5-10 min; after the stirring was completed, a mixed liquid was obtained; the mixed liquid was treated by ultrasonic waves for 10-20 min to obtain an antifreezing early strength agent solution;

[0087] (7) 80 parts of a compound powder was added to 25 parts of the antifreezing early strength agent solution and transferred to a clean mortar stirrer; the stirring blade revolution speed of the clean mortar stirrer was 62 r / min and the stirring blade rotation speed of the clean mortar stirrer was 140 r / min, and the mixture was slowly stirred for 1 min; the stirring blade revolution speed of the clean mortar stirrer was 125 r / min and the stirring blade rotation speed of the clean mortar stirrer was 285 r / min, and the mixture was quickly stirred for 1 min to obtain a nano-modified low-temperature early strength lunar soil curing agent.

[0088] Example 4

[0089] The nano-modified low-temperature early strength lunar soil curing agent provided in the example is prepared from raw materials in the following proportions by weight, and the preparation method comprises the following steps:

[0090] (1) 60 parts of sulphoaluminate cement clinker, 20 parts of Portland cement clinker and 3 parts of gypsum are mixed uniformly, poured into a ball mill for ball milling for 75 min, the rotating speed of the ball mill is 200 r / min, to obtain a ground material A; the ground material A is poured into a vibrating screen for passing through a square hole screen with a mesh size of 75 μm to obtain a ground material B with a particle size of less than 75 μm; the ground material B is dried in an oven with a temperature of 105 ℃ for 60 h to a constant weight to obtain a compounded powder;

[0091] (2) 6 parts of urea, 8 parts of calcium nitrate, 3 parts of sodium nitrite, 2 parts of calcium chloride and 0.5 parts of polycarboxylate superplasticizer are sequentially added into water, and placed on a magnetic stirrer for stirring, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 10-20 min, after the stirring is completed, the mixture is left to stand for 2-4 h to obtain an anti-freezing agent solution.

[0092] (3) 1.5 parts of cetyltrimethylammonium bromide, 0.5 parts of sodium salicylate and deionized water are mixed uniformly, heated to complete dissolution to obtain a first reaction liquid; 0.2 parts of triethylamine and 20 parts of tetraethyl orthosilicate are added into the first reaction liquid, stirred uniformly, cooled to room temperature to obtain a second reaction liquid; the second reaction liquid is washed by anhydrous ethanol, vacuum dried at 45 ℃, and ground to obtain a first reaction material; the first reaction material is placed in an oven for heat preservation at 600 ℃ for 4.5 h to obtain white powder nano-silicon dioxide;

[0093] (4) 1 part of nano-silicon dioxide is added into 30 parts of anhydrous ethanol, ultrasonically dispersed uniformly to obtain a first dispersion liquid; 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 1 part of ammonia water are added into the first dispersion liquid, reacted at room temperature for 6 h to obtain a second reaction material; the second reaction material is washed by anhydrous ethanol, vacuum dried to obtain urchin-shaped nano-silicon dioxide;

[0094] (5) 1 part of nano-silicon dioxide and 0.05 parts of nano-magnetic four-oxide three-iron are added into 30 parts of anhydrous ethanol, ultrasonically dispersed uniformly to obtain a second dispersion liquid; 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 2 parts of ammonia water are added into the second dispersion liquid, reacted at room temperature for 6 h to obtain a third reaction material; the third reaction material is separated by a strong magnetic field, washed by anhydrous ethanol, vacuum dried to obtain magnetic urchin-shaped nano-silicon dioxide;

[0095] (6) 0.2 parts of nano-silicon dioxide, 2 parts of sea urchin-shaped nano-silicon dioxide and 0.5 parts of magnetic sea urchin-shaped nano-silicon dioxide are added into 90 parts of the anti-freezing agent solution, and stirring is carried out on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 5-10 min, after the stirring is completed, the mixed solution is obtained; the mixed solution is placed in an ultrasonic cleaning instrument, ultrasonic treatment is carried out for 10-20 min, and the anti-freezing early strength agent solution is obtained;

[0096] (7) 75 parts of the compound powder are added into 30 parts of the anti-freezing early strength agent solution, and are transferred to a clean paste stirrer, slow stirring is carried out for 1 min, the stirring blade revolution speed of the clean paste stirrer is 62 r / min, and the stirring blade rotation speed of the clean paste stirrer is 140 r / min; then fast stirring is carried out for 1 min, the stirring blade revolution speed of the clean paste stirrer is 125 r / min, and the stirring blade rotation speed of the clean paste stirrer is 285 r / min, and the nano-modified low-temperature early strength lunar soil curing agent is obtained.

[0097] Example 5

[0098] The nano-modified low-temperature early strength lunar soil curing agent provided in the embodiment, the raw materials are in parts by weight, and the preparation method comprises the following steps:

[0099] (1) 75 parts of sulphoaluminate cement clinker, 15 parts of Portland cement clinker and 2 parts of gypsum are uniformly mixed, poured into a ball mill and ball milled for 80 min, the rotation speed of the ball mill is 200 r / min, and ground material A is obtained; the ground material A is poured into a vibrating screen and passed through a square hole screen with a size of 75 μm, and ground material B with a particle size of less than 75 μm is obtained; the ground material B is placed in an oven with a temperature of 105 ℃ and dried to constant weight for 60 h, and the compound powder is obtained;

[0100] (2) 6 parts of urea, 6 parts of calcium nitrate, 2 parts of sodium nitrite, 1 part of calcium chloride and 0.75 parts of polycarboxylate superplasticizer are sequentially added into water, and stirring is carried out on a magnetic stirrer, the stirring speed of the magnetic stirrer is set to 2500 r / min, the stirring time is 10-20 min, after the stirring is completed, the anti-freezing agent solution is obtained.

[0101] (3) 1.5 parts of cetyltrimethylammonium bromide, 0.5 parts of sodium salicylate and deionized water are uniformly mixed and heated to completely dissolve, and a first reaction liquid is obtained; 0.2 parts of triethylamine and 20 parts of tetraethyl orthosilicate are added into the first reaction liquid, stirred uniformly, and cooled to room temperature, and a second reaction liquid is obtained; the second reaction liquid is washed by anhydrous ethanol, vacuum dried at 45 ℃, and ground, and a first reaction substance is obtained; the first reaction substance is placed in an oven and kept at 600 ℃ for 4.5 h, and white powder nano-silicon dioxide is obtained;

[0102] (4) adding 1 part of nano-silica into 20 parts of anhydrous ethanol, uniformly dispersing by ultrasonic, to obtain a first dispersion liquid; adding 2 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 1 part of ammonia water into the first dispersion liquid, reacting at room temperature for 6 hours, to obtain a second reactant; washing the second reactant by anhydrous ethanol, vacuum drying, to obtain sea urchin-shaped nano-silica;

[0103] (5) adding 1 part of nano-silica and 0.05 part of nano-ferroferric oxide into 30 parts of anhydrous ethanol, uniformly dispersing by ultrasonic, to obtain a second dispersion liquid; adding 4 parts of 3-(isobutenoyloxy) propyl trimethoxysilane and 1 part of ammonia water into the second dispersion liquid, reacting at room temperature for 6 hours, to obtain a third reactant; separating the third reactant by a strong magnetic field, washing by anhydrous ethanol, vacuum drying, to obtain magnetic sea urchin-shaped nano-silica;

[0104] (6) adding 0.2 part of nano-silica, 0.5 part of sea urchin-shaped nano-silica and 1.5 part of magnetic sea urchin-shaped nano-silica into 100 parts of an antifreezing agent solution, stirring on a magnetic stirrer, setting the stirring speed of the magnetic stirrer at 2500 r / min, setting the stirring time at 5-10 min, after the stirring is completed, obtaining a mixed liquid; placing the mixed liquid in an ultrasonic cleaning instrument, ultrasonic treating for 10-20 min, to obtain an antifreezing early strength agent solution;

[0105] (7) adding 70 parts of a compound powder into 20 parts of the antifreezing early strength agent solution, transferring to a clean mortar stirrer, slow stirring for 1 min, the stirring blade revolution speed of the clean mortar stirrer being 62 r / min, the stirring blade rotation speed of the clean mortar stirrer being 140 r / min; fast stirring for 1 min, the stirring blade revolution speed of the clean mortar stirrer being 125 r / min, the stirring blade rotation speed of the clean mortar stirrer being 285 r / min, to obtain a nano-modified low-temperature early strength lunar soil curing agent.

[0106] Example 6

[0107] The nano-modified low-temperature early strength lunar soil curing agent provided in the embodiment, the raw materials are in parts by weight, and the preparation method comprises the following steps:

[0108] (1) uniformly mixing 80 parts of sulphoaluminate cement clinker, 10 parts of portland cement clinker and 1 part of gypsum, pouring into a ball mill for ball milling for 70 min, the rotation speed of the ball mill being 200 r / min, to obtain a ground material A; pouring the ground material A into a vibrating screen to pass through a square hole screen with a mesh size of 75 μm, to obtain a ground material B with a particle size of less than 75 μm; placing the ground material B into an oven with a temperature of 105 ℃ for drying to constant weight for 60 h, to obtain a compound powder;

[0109] (2) adding 10 parts of urea, 15 parts of calcium nitrate, 3 parts of sodium nitrite, 2 parts of calcium chloride and 1.5 parts of polycarboxylate water reducing agent into water in sequence, and placing on a magnetic stirrer for stirring, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 10-20 min, after the stirring is completed, standing for 2-4 h, and obtaining the antifreeze solution.

[0110] (3) uniformly mixing 2 parts of cetyltrimethylammonium bromide, 1 part of sodium salicylate and deionized water, heating to complete dissolution, obtaining a first reaction liquid; adding 0.5 parts of triethylamine, 15 parts of tetraethyl orthosilicate into the first reaction liquid, stirring uniformly, cooling to room temperature, obtaining a second reaction liquid; washing the second reaction liquid by anhydrous ethanol, vacuum drying at 45 ℃, grinding, obtaining a first reaction substance; placing the first reaction substance in an oven at 600 ℃ for 4.5 h, obtaining white powder nano-silica;

[0111] (4) adding 0.5 parts of nano-silica into 10 parts of anhydrous ethanol, ultrasonic dispersion uniformly, obtaining a first dispersion liquid; adding 2 parts of 3-(isobutenoyloxy) propyl trimethoxysilane, 0.5 parts of ammonia water into the first dispersion liquid, reacting at room temperature for 6 h, obtaining a second reaction substance; washing the second reaction substance by anhydrous ethanol, vacuum drying, obtaining urchin-shaped nano-silica;

[0112] (5) adding 1.5 parts of nano-silica and 0.1 parts of nano-ferroferric oxide into 35 parts of anhydrous ethanol, ultrasonic dispersion uniformly, obtaining a second dispersion liquid; adding 8 parts of 3-(isobutenoyloxy) propyl trimethoxysilane, 3 parts of ammonia water into the second dispersion liquid, reacting at room temperature for 6 h, obtaining a third reaction substance; separating the third reaction substance by a strong magnetic field, and washing by anhydrous ethanol, vacuum drying, obtaining magnetic urchin-shaped nano-silica;

[0113] (6) adding 0.2 parts of nano-silica, 0.5 parts of urchin-shaped nano-silica and 1.5 parts of magnetic urchin-shaped nano-silica into 90 parts of the antifreeze solution, and placing on a magnetic stirrer for stirring, setting the stirring speed of the magnetic stirrer to 2500 r / min, and stirring for 5-10 min, after the stirring is completed, obtaining a mixed liquid; placing the mixed liquid in an ultrasonic cleaner, ultrasonic treating for 10-20 min, obtaining an antifreeze early strength agent solution;

[0114] (7) 65 parts of the compound powder is added into 25 parts of the anti-freezing early strength agent solution, and is transferred into a neat paste stirrer, and is stirred slowly for 1 min, the revolution speed of the stirring blade of the neat paste stirrer is 62 r / min, and the rotation speed of the stirring blade of the neat paste stirrer is 140 r / min; and then is stirred quickly for 1 min, the revolution speed of the stirring blade of the neat paste stirrer is 125 r / min, and the rotation speed of the stirring blade of the neat paste stirrer is 285 r / min, to obtain the nano-modified low-temperature early strength lunar soil solidifying agent.

[0115] The simulated lunar soil is solidified by the nano-modified low-temperature early strength lunar soil solidifying agent prepared in the above examples 1-6 respectively, to obtain a solidified body, and the mass ratio of the solidifying agent to the simulated lunar soil is 20:80.

[0116] Comparative Example 1

[0117] The simulated lunar soil is solidified by the ordinary Portland cement 42.5 as the solidifying agent, to obtain a solidified body, and the mass ratio of the solidifying agent to the simulated lunar soil is 20:80.

[0118] Comparative Example 2

[0119] The simulated lunar soil is solidified by the sulphoaluminate cement 42.5 as the solidifying agent, to obtain a solidified body, and the mass ratio of the solidifying agent to the simulated lunar soil is 20:80.

[0120] The solidified bodies prepared in the above examples 1-6 and comparative examples 1-2 are placed into a low-temperature (-5 ℃) curing box for curing for 28 d, and the unconfined compressive strength of the samples is tested, and the test results are shown in Table 1; the above samples are continuously placed into a vacuum curing box for curing for 28 d, and the unconfined compressive strength of the samples is tested, and the test results are shown in Table 2; and the initial setting time, final setting time and freezing temperature of the samples at low temperature are tested, and the test results are shown in Table 3.

[0121] Table 1: Compressive strength of the simulated lunar soil solidified body

[0122]

[0123] Table 2: Influence of vacuum curing on the compressive strength of the simulated lunar soil solidified body

[0124]

[0125] Table 3: Initial setting time, final setting time and paste freezing temperature of the simulated lunar soil solidified body

[0126]

[0127] From the above experimental data, the 1d strength of the simulated lunar soil solidified body cured by the nano-modified low-temperature early strength lunar soil curing agent can reach 8.7 MPa, and the lowest can reach more than 6.6 MPa. And the initial setting time is fast in the low temperature environment, all less than 45 min, and the freezing temperature is also lower than the freezing point, the introduction of nano materials in the nano-modified low-temperature early strength lunar soil curing agent plays the role of crystal nucleus in the cement hydration process, can promote the cement hydration process, and then accelerate the early hydration reaction rate of cement in low temperature environment, promote the growth and development of hydration products, improve the denseness of the cement matrix, promote the development of early strength of cement stone in low temperature environment, accelerate the construction progress and reduce the construction cost, can meet the requirements of low temperature early strength, can be widely used in lunar surface construction and other low temperature engineering.

[0128] Finally, it should also be noted that the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles or equipment including a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such processes, methods, articles or equipment.

[0129] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0130] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a nano-modified low-temperature early-strength lunar soil solidifying agent, characterized in that, The preparation method includes the following steps: S1. Mix sulfoaluminate cement clinker, silicate cement clinker and gypsum evenly, and then grind, sieve and dry to obtain compound powder; S2. Add urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylate superplasticizer to water in sequence, stir evenly to obtain antifreeze solution; S3. Mix hexadecyltrimethylammonium bromide, sodium salicylate, and deionized water evenly and heat until completely dissolved to obtain the first reaction solution; add triethylamine and tetraethyl orthosilicate to the first reaction solution, stir evenly, and cool to room temperature to obtain the second reaction solution; wash the second reaction solution with anhydrous ethanol, vacuum dry at 45 °C, and grind to obtain the first reactant; place the first reactant at 600 °C for 4.5 h to obtain white powdered nano-silica; S4. Add the nano-silica to anhydrous ethanol and disperse it evenly by ultrasonication to obtain a first dispersion; add 3-(isobutenoyloxy)propyltrimethoxysilane and ammonia to the first dispersion and react at room temperature for 6 h to obtain a second reactant; wash the second reactant with anhydrous ethanol and dry it under vacuum to obtain sea urchin-shaped nano-silica. S5. Add the nano-silica and nano-iron oxide to anhydrous ethanol, and disperse them evenly by ultrasonication to obtain a second dispersion; add 3-(isobutenoyloxy)propyltrimethoxysilane and ammonia to the second dispersion, and react at room temperature for 6 h to obtain a third reactant; separate the third reactant by a strong magnetic field, wash it with anhydrous ethanol, and vacuum dry it to obtain magnetic sea urchin-like nano-silica. S6. Add the nano-silica, the sea urchin-shaped nano-silica, and the magnetic sea urchin-shaped nano-silica to the antifreeze solution, stir until uniform, and obtain a mixture; subject the mixture to ultrasonic treatment to obtain an antifreeze early strength agent solution; S7. Add the compound powder to the antifreeze early strength agent solution and stir evenly to obtain nano-modified low-temperature early strength soil solidification agent.

2. The preparation method of the nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 1, characterized in that, The process involves uniformly mixing sulfoaluminate cement clinker, silicate cement clinker, and gypsum, followed by grinding, sieving, and drying to obtain a compound powder comprising: The sulfoaluminate cement clinker, the silicate cement clinker, and the gypsum are mixed evenly to obtain a mixture; The mixture was poured into a ball mill and ball-milled for 60-80 min to obtain powder A; The ground material A is poured into a vibrating screen and passed through a 75 μm square hole sieve to obtain ground material B with a particle size of less than 75 μm. The ground material B is placed in an oven at 105 °C and dried for 48–60 h until constant weight is obtained to obtain the compound powder.

3. The preparation method of the nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 2, characterized in that, In step S2, urea, calcium nitrate, sodium nitrite, calcium chloride and polycarboxylate superplasticizer are added to water in sequence and placed on a magnetic stirrer for stirring. The stirring speed of the magnetic stirrer is set to 2500 r / min and the stirring time is 10 to 20 min. After stirring, the mixture is left to stand for 2 to 4 h to obtain the antifreeze solution.

4. The preparation method of the nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 3, characterized in that, In step S6, the nano-silica, the sea urchin-shaped nano-silica, and the magnetic sea urchin-shaped nano-silica are added to the antifreeze solution, and the solution is placed on a magnetic stirrer for stirring. The stirring speed of the magnetic stirrer is set to 2500 r / min, and the stirring time is 5-10 min. After stirring, a mixture is obtained. The mixture is placed in an ultrasonic cleaner and ultrasonically treated for 10-20 min to obtain an antifreeze early strength agent solution.

5. The preparation method of the nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 4, characterized in that, The step of adding the compound powder to the antifreeze and early strength agent solution and stirring evenly to obtain the nano-modified low-temperature early strength lunar soil solidification agent specifically includes: The compound powder is added to the antifreeze early strength agent solution to obtain a first mixture; The first mixture is transferred to a paste mixer and stirred for 1 min to obtain a second mixture; wherein the revolution speed of the mixing blades of the paste mixer is 62 r / min and the rotation speed of the mixing blades of the paste mixer is 140 r / min. The second mixture is stirred for another 1 minute to obtain a nano-modified low-temperature early-strength soil solidifier; wherein the revolution speed of the stirring blade of the slurry mixer is 125 r / min and the rotation speed of the stirring blade of the slurry mixer is 285 r / min.

6. A nano-modified low-temperature early-strength lunar soil solidifying agent, characterized in that, The curing agent is prepared by the method of preparing nano-modified low-temperature early-strength lunar soil curing agent according to any one of claims 1-5; the curing agent is composed of the following components by weight: 60-80 parts of compound powder and 10-30 parts of antifreeze early-strength agent solution.

7. The nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 6, characterized in that, The compound powder is composed of 60-80 parts of sulfoaluminate cement clinker, 5-25 parts of silicate cement clinker, and 1-5 parts of gypsum by weight. The particle size of the compound powder is less than 75 μm.

8. The nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 7, characterized in that, The antifreeze early strength agent solution comprises, by weight, 80-120 parts of antifreeze solution, 0.1-3 parts of nano silica, 0.1-3 parts of sea urchin-shaped nano silica, and 0.1-3 parts of magnetic sea urchin-shaped nano silica. The sea urchin-like nano-silica comprises, by weight, 0.5-1 part nano-silica, 10-30 parts ethanol, 2-6 parts 3-(isobutenoyloxy)propyltrimethoxysilane, and 0.5-3 parts ammonia. The magnetic sea urchin-like nano silica comprises, by weight, 0.5-1.5 parts nano silica, 5-35 parts ethanol, 2-8 parts 3-(isobutenoyloxy)propyltrimethoxysilane, 0.5-4 parts ammonia, and 0.01-1 parts nano iron oxide.

9. The nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 8, characterized in that, The antifreeze solution comprises, by weight, 5-15 parts urea, 5-15 parts calcium nitrate, 1-6 parts sodium nitrite, 1-4 parts calcium chloride, and 0.5-2.5 parts polycarboxylate superplasticizer.

10. The nano-modified low-temperature early-strength lunar soil solidifying agent according to claim 9, characterized in that, The nano-silica comprises, by weight, 1-3 parts of hexadecyltrimethylammonium bromide, 0.5-1.5 parts of sodium salicylate, 0.1-1 parts of triethylamine, and 10-25 parts of tetraethyl orthosilicate.

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