Modified cement-water glass slurry and preparation method thereof

Abstract

The invention discloses modified cement-water glass slurry and a preparation method thereof, and belongs to the technical field of building material preparation. The preparation method comprises the following steps: weighing the following raw materials in parts by weight: 50-70 parts of Portland cement, 20-35 parts of a water glass solution, silica fume, modified nano-silica, an early strength agent and the like, carrying out dry mixing on solid powder, stirring with part of deionized water to form base slurry, adding the water glass solution and the rest deionized water, and carrying out high-speed dispersion to obtain a slurry; and finally, carrying out ultrasonic treatment for 10-15 minutes at the frequency of 20-40 kHz and the power of 300-500 W. Wherein the early strength agent is compounded by triethanolamine and sodium sulfate according to the ratio of 1: 2-1: 3. According to the method, through raw material compounding and process optimization, the dispersity, the early strength and the crack resistance of the slurry are improved, and the method is mainly used for grouting operation in the field of construction engineering such as foundation reinforcement and water prevention and leakage stoppage.

Description

Technical Field

[0001] The present invention belongs to the technical field of building material preparation, and particularly relates to a modified cement-sodium silicate slurry and a preparation method thereof. Background Art

[0002] In the field of construction engineering, the cement-sodium silicate slurry, as a commonly used grouting material, is widely applied to scenarios such as foundation reinforcement, waterproofing and leakage stoppage, and mine curtain grouting. Its performance directly affects the project quality and construction efficiency. The traditional cement-sodium silicate grouting system is mainly composed of portland cement and sodium silicate solution. After the two are mixed, hydrolysis and condensation reactions occur to form a gel. However, the surface of cement particles in this system has polar groups and is prone to form aggregates through van der Waals forces in an aqueous medium, resulting in uneven dispersion of the gelling material and insufficient hydration reaction. Especially in the absence of efficient dispersion means, the aggregation problem of cement particles is more prominent. Moreover, the sodium silicate solution (aqueous sodium silicate solution) reacts with the hydration product calcium hydroxide of cement to form calcium silicate gel, but the reaction rate is restricted by factors such as the mixing uniformity of raw materials and reaction temperature. The traditional stirring process is difficult to achieve sufficient contact between the two phases, resulting in insufficient gel formation and difficult improvement of early strength. This leads to the comprehensive performance of the product being unable to meet the project requirements. Therefore, it is urgent to improve the preparation method of the modified cement-sodium silicate slurry to meet the actual needs of high-performance grouting materials for engineering applications. Summary of the Invention

[0003] An object of an embodiment of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0004] The object of the present invention also lies in solving the following problems: The traditional cement-sodium silicate slurry has problems of slow early strength development and insufficient slurry stability, specifically manifested as easy aggregation of cement particles leading to insufficient hydration, insufficient reaction between sodium silicate and cement, and no introduction of functional modified components to improve interfacial forces, resulting in easy stratification during slurry storage and transportation and poor crack resistance after hardening.

[0005] In the traditional dry-mixing process, the solid powder is unevenly dispersed. Especially, the early strength agent is difficult to uniformly coat the cement particles, resulting in the ineffective exertion of the early strength component and affecting the starting speed of cement hydration and the improvement effect of early strength.

[0006] When the ultrasonic treatment frequency and temperature are not optimized, the aggregation problem of nanoparticles cannot be fully solved, and the temperature fluctuation of the interfacial reaction will affect the reaction rate between sodium silicate and the hydration product of cement, resulting in insufficient gel formation and slurry stability fluctuation.

[0007] The traditional preparation process does not undergo aging treatment, the internal particle interaction force in the slurry is not fully formed, stratification is likely to occur during storage, and the structural density is insufficient after hardening, affecting the later strength and crack resistance.

[0008] The agglomeration of cement particles leads to a decrease in fluidity, and no fiber-reinforcing components are introduced. After the slurry hardens, there are many microcracks inside, and the crack resistance is insufficient. The comprehensive performance needs to be improved through the dispersion of water-reducing agents and the fiber bridging effect.

[0009] The problems of nanoparticle agglomeration and loose structure in the interfacial transition zone have not been solved, and the lack of three-dimensional physical network reinforcement leads to poor slurry stability and insufficient crack resistance of the hardened body. The interfacial structure needs to be optimized through the fiber network and the adsorption effect of graphene oxide.

[0010] The traditional water consumption calculation does not consider the specific surface area of the cementitious material and the water reduction rate of the water-reducing agent, resulting in an unreasonable water-binder ratio, and it is easy to have insufficient fluidity or a decrease in strength. Precise calculation is required to balance the construction performance and hardened strength of the slurry.

[0011] The unmodified nano-silica has a high surface energy, is easy to agglomerate and form defects in the slurry, and has a weak interfacial bonding force with the cement matrix, so it cannot effectively exert the nano-reinforcement effect. Surface modification is required to improve the dispersibility and interfacial compatibility.

[0012] The traditional curing process does not combine microwave assistance. During the hardening process of the slurry, the heat distribution is uneven, the hydration reaction is insufficient, and the early strength development is slow. Microwave energy is required to accelerate the formation of the gel and the densification of the structure.

[0013] Another object of the present invention is to provide a preparation method of a modified cement-sodium silicate slurry.

[0014] For this reason, the technical solution provided by the present invention is as follows: In the first aspect, a preparation method of a modified cement-sodium silicate slurry includes: 1) Weigh raw materials by weight: 50-70 parts of portland cement, 20-35 parts of sodium silicate solution, 5-10 parts of silica fume, 3-6 parts of modified nano-silica, and 1-3 parts of early strength agent. The early strength agent is compounded by triethanolamine and sodium sulfate according to a mass ratio of 1:2-1:3; 2) Put the portland cement, silica fume, nano-silica, and early strength agent weighed in step 1) into a mixer and dry mix for 3-5 minutes to uniformly mix the solid powder materials to form a composite powder; 3) Add deionized water accounting for 60%-70% of the total water consumption to the composite powder obtained in step 2), and stir at a speed of 400-600 rpm for 8-12 minutes to make the water and the composite powder fully contact to form a base slurry; 4) Add the sodium silicate solution weighed in step 1) and the remaining 30%-40% deionized water to the base slurry formed in step 3). First, disperse at a high speed of 800-1000 rpm for 5-8 minutes to preliminarily mix the sodium silicate solution and the base slurry evenly. Then transfer the mixed solution to an ultrasonic treatment device and treat it at a frequency of 20-40 kHz and a power of 300-500 W for 10-15 minutes. Promote the interfacial reaction between sodium silicate and cement particles through ultrasonic cavitation to obtain a modified cement-sodium silicate slurry.

[0015] Preferably, in the preparation method of the modified cement-sodium silicate slurry, the dry mixing process in step 2) adopts two-stage treatment: first premix at a speed of 200-300 rpm for 2 minutes to evenly coat the early strength agent on the cement particles, and then increase the speed to 400-500 rpm and disperse for 1-3 minutes.

[0016] Preferably, in the preparation method of the modified cement-sodium silicate slurry, during the ultrasonic treatment process in step 4), the frequency of the ultrasonic treatment device is 25-35 kHz, and the temperature is maintained at a constant temperature of 30-40 °C during the treatment.

[0017] Preferably, in the preparation method of the modified cement-sodium silicate slurry, an aging treatment is also carried out after the ultrasonic treatment in step (4): stir the prepared slurry at a speed of 50-100 rpm in an environment of 25-30 °C for 1-2 hours.

[0018] Preferably, in the preparation method of the modified cement-sodium silicate slurry, the raw materials in step 1) further include: 0.5-1.5 parts of polycarboxylate water reducer and 0.5-1.0 kg / m³ of short-cut carbon fiber. In step 2), put the short-cut carbon fiber, early strength agent, cement, silica fume, and nano-silica into a mixer and carry out dry mixing. Put the polycarboxylate water reducer into the base slurry synchronously when adding deionized water in step 3).

[0019] Preferably, in the preparation method of the modified cement-sodium silicate slurry, the raw materials in step 1) further include 1-2 kg / m³ of short-cut polypropylene fiber and 1-3 parts of graphene oxide dispersion liquid, and the solid content in the graphene oxide dispersion liquid is 2-5 wt%. In step 2), put the short-cut polypropylene fiber, early strength agent, cement, silica fume, and nano-silica into a mixer and carry out dry mixing. Put the graphene oxide dispersion liquid into the base slurry synchronously when adding deionized water in step 3).

[0020] Preferably, in the preparation method of the modified cement-sodium silicate slurry, the total water consumption in step 3) and step 4) is determined as follows: First, calculate the theoretical water demand according to the total specific surface area of cement and silica fume in step 1), and the calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); then adjust the actual water addition amount according to the water reduction rate of the polycarboxylate water reducer. The water reduction rate of the polycarboxylate water reducer is 25%-30%, and the water-binder ratio (water / binder) is maintained at 0.35-0.40, where the binder includes the total mass of portland cement, silica fume and nano-silica, so as to obtain the total water consumption.

[0021] Preferably, in the preparation method of the modified cement-sodium silicate slurry, the modification method of the modified nano-silica includes: dispersing nano-silica in an anhydrous ethanol solution to form a dispersion system with a solid-liquid ratio of 1:10, adding 3-aminopropyltriethoxysilane accounting for 1%-3% of the mass of nano-silica, magnetically stirring at 60°C-80°C for 2 to 3 hours, and then filtering and drying to obtain modified nano-silica.

[0022] Preferably, in the preparation method of the modified cement-sodium silicate slurry, after the aging treatment, it also includes a microwave-assisted curing process, and the microwave-assisted curing process includes the following steps: Transfer the aged slurry into a microwave curing box and process it at a frequency of 2-3 GHz and a power of 300-600W for 5-10 minutes.

[0023] In the second aspect, a modified cement-sodium silicate slurry is provided, and the modified cement-sodium silicate slurry is prepared by the method described in any one of the above.

[0024] The embodiments of the present invention at least include the following beneficial effects: Through precise proportioning of raw materials, staged stirring process and ultrasonic enhanced dispersion, the present invention can achieve a cement particle dispersion index ≥ 0.90, a nano-silica aggregate particle size ≤ 150nm, an increase in compressive strength compared with the traditional process, and an improvement in crack resistance (fracture energy), effectively solving the problems of low early strength and poor stability of traditional slurries, and being applicable to rapid grouting construction in projects such as foundation reinforcement and waterproof plugging.

[0025] In addition, the two-stage dry mixing process of the present invention pre-mixes and wraps the early strength agent at a low speed and disperses and breaks the agglomerates at a high speed, so that the early strength components are evenly distributed, promoting the early hydration of cement; the ultrasonic treatment optimizes the frequency and constant temperature control, enhances the dispersion of nanoparticles, and promotes the full reaction of sodium silicate and cement hydration products; the aging treatment promotes the physical and chemical interaction between particles through low-speed stirring and constant temperature environment, reduces storage stratification and improves the density of the hardened body; the addition of polycarboxylate superplasticizer and fibers improves the particle dispersion and crack resistance through steric hindrance effect and bridging action; the introduction of graphene oxide and polypropylene fibers forms a three-dimensional network structure and enhances the density of the interfacial transition zone; the accurate calculation of water consumption combined with the adjustment of superplasticizer ensures a reasonable water-binder ratio and balances fluidity and strength; the surface modification of nano-silica reduces the surface energy, avoids agglomeration and improves the interfacial compatibility; the microwave-assisted curing accelerates the gelling reaction through high-frequency electromagnetic field, promotes the early strength development and structural densification. These improvements systematically solve the problems of uneven dispersion, insufficient reaction, poor stability and insufficient crack resistance of traditional slurries, and improve the comprehensive performance of grouting materials from the dimensions of raw material dispersion, interfacial reaction, process adaptability, etc., meeting the actual needs of engineering applications for high-performance grouting materials.

[0026] Other advantages, objectives and features of the embodiments of the present invention will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the embodiments of the present invention. Detailed implementation manners

[0027] The following further elaborates on the embodiments of the present invention in conjunction with examples, so that those skilled in the art can implement them with reference to the text of the specification.

[0028] The present invention provides a method for preparing a modified cement-sodium silicate slurry, comprising the following steps: A method for preparing a modified cement-sodium silicate slurry, comprising: 1) Weigh the raw materials by weight parts: 50 - 70 parts of portland cement, 20 - 35 parts of water glass solution, 5 - 10 parts of silica fume, 3 - 6 parts of modified nano - silica, and 1 - 3 parts of early strength agent. The early strength agent is compounded by triethanolamine and sodium sulfate in a mass ratio of 1:2 - 1:3. The raw material weighing step includes weighing 50 - 70 parts of portland cement, 20 - 35 parts of water glass solution, 5 - 10 parts of silica fume, 3 - 6 parts of modified nano - silica, and 1 - 3 parts of early strength agent (compounded by triethanolamine and sodium sulfate in a ratio of 1:2 - 1:3). Among them, the portland cement can be 42.5 - grade ordinary portland cement (meeting the GB 175 standard), the water glass solution can be sodium silicate aqueous solution with a modulus of 3.0 - 3.5 (concentration 40 - 50 Baumé), the silica fume can be ultrafine silica fume with a specific surface area ≥ 15000 m² / kg (silicon dioxide content ≥ 92%), and triethanolamine (analytical pure, purity ≥ 99%) and sodium sulfate (industrial grade, purity ≥ 98%) in the early strength agent are accurately compounded by mass ratio. The weighing equipment can use an electronic batching scale (accuracy ±0.1%). The raw material sources need to meet the building materials industry standards to ensure the stability of the components.

[0029] 2) Put the portland cement, silica fume, nano - silica, and early strength agent weighed in step 1) into a mixer and dry - mix at a speed of 200 - 300 rpm for 3 - 5 minutes to uniformly mix the solid powders to form a composite powder. 3) Add deionized water accounting for 60% - 70% of the total water consumption to the composite powder obtained in step 2) and stir at a speed of 400 - 600 rpm for 8 - 12 minutes to make the water and the composite powder fully contact to form a base slurry. Put the portland cement, silica fume, modified nano - silica, and early strength agent into a mixer for dry - mixing at a speed of 200 - 300 rpm for 3 - 5 minutes. The mixer can be a double - cone rotary mixer or a plough - share mixer to ensure uniform mixing of the powders under the action of rotation and plough - share shearing. After dry - mixing, add deionized water accounting for 60% - 70% of the total water consumption and stir at a speed of 400 - 600 rpm for 8 - 12 minutes to form a base slurry. The stirring equipment can use a planetary mixer (with spiral blades and scrapers). This step realizes the dispersion of the powders through low - speed dry - mixing and then promotes the preliminary hydration of cement particles through medium - speed wet - mixing, laying a foundation for subsequent reactions.

[0030] 4) Add the water glass solution weighed in step 1) and the remaining 30%-40% deionized water to the base slurry formed in step 3). First, disperse at a high speed of 800-1000 rpm for 5-8 minutes to preliminarily mix the water glass solution and the base slurry evenly. Then transfer the mixed solution to an ultrasonic treatment device and treat it at a frequency of 20-40 kHz and a power of 300-500 W for 10-15 minutes to promote the interfacial reaction between water glass and cement particles through ultrasonic cavitation, thus obtaining a modified cement-water glass slurry. Add the water glass solution and the remaining 30%-40% deionized water to the base slurry. First, disperse at a high speed of 800-1000 rpm for 5-8 minutes, and then transfer it to an ultrasonic treatment device (frequency 20-40 kHz, power 300-500 W) for 10-15 minutes. The high-speed dispersion equipment can be a shear-type disperser (equipped with a serrated dispersion disk), and the ultrasonic treatment device can be a tank-type ultrasonic cleaner (with an internal temperature control module). High-speed dispersion quickly mixes the water glass solution and the base slurry, and ultrasonic treatment uses the cavitation effect to break nanoscale aggregates and promote the interfacial reaction between cement particles and water glass. The process parameters need to be adjusted according to the slurry viscosity (target value ≤ 250 mPa・s) and dispersion stability (settling rate ≤ 5%). The ultrasonic frequency is preferably 30 kHz to balance the dispersion efficiency and energy consumption. The finally obtained slurry needs to pass a fluidity test (slump ≥ 180 mm) and an early strength test (1-day compressive strength ≥ 10 MPa) to ensure meeting the requirements of the grouting project.

[0031] Through precise proportioning of raw materials, a staged stirring process, and ultrasonic enhanced dispersion, the present invention can achieve a cement particle dispersion index ≥ 0.90, a nano-silica aggregate particle size ≤ 150 nm, an increase in compressive strength compared to the traditional process, and an improvement in crack resistance (fracture energy), effectively solving the problems of low early strength and poor stability of traditional slurries, and being applicable to rapid grouting construction for projects such as foundation reinforcement and waterproof plugging.

[0032] In one of the embodiments of the present invention, preferably, the dry mixing process in step 2) is carried out in two stages: First, premix at a speed of 200 - 300 rpm for 2 minutes to evenly coat the early strength agent on the cement particles. The premixing equipment can be a double-cone rotary mixer or a ploughshare mixer. The former realizes the flipping and mixing of the powder through the rotation of the cylinder, and the latter promotes dispersion through the shearing action of the ploughshare blades. The early strength agent is compounded by triethanolamine and sodium sulfate in a ratio of 1:2 - 1:3. Among them, triethanolamine (analytical pure, purity ≥ 99%) has polar groups and can be adsorbed on the surface of cement particles, while sodium sulfate (industrial grade, purity ≥ 98%) promotes the early hydration of cement through ion exchange. The rotational speed setting in the premixing stage is based on the powder fluidity test, and it is necessary to ensure that the early strength agent powder forms an initial adsorption layer on the surface of cement particles to avoid agglomeration. Then, increase the rotational speed to 400 - 500 rpm and disperse for 1 - 3 minutes to break the agglomerates of silica fume and nano-silica, forming a more uniformly dispersed composite powder. The dispersion equipment can be a horizontal screw ribbon mixer or a high-speed shear disperser. The former realizes the kneading and mixing of the powder through the bidirectional movement of the screw ribbon blades, and the latter breaks the agglomeration structure through the high-speed rotating shear cutter head. The high-speed shear force in this stage can further evenly distribute the early strength agent adsorbed on the surface of cement particles, and at the same time disperse the silica fume and modified nano-silica particles. The determination of the rotational speed threshold needs to consider both the dispersion efficiency and energy consumption, and is adjusted by testing the bulk density (target value ≥ 1.2 g / cm³) and particle size distribution (D50 ≤ 50 μm) of the powder after mixing to ensure the uniformity of the composite powder.

[0033] Through the two-stage dry mixing process, the degree of uniform distribution of the early strength agent on the surface of cement particles is improved. The adsorption of triethanolamine accelerates the early hydration of cement particles, and sodium sulfate promotes the rapid formation of ettringite crystals. The two work together to increase the 1-day compressive strength of the slurry by 25% - 30% compared with the traditional single-stage stirring process. At the same time, the high-speed dispersion step breaks the initial agglomerates of silica fume and nano-silica, increasing the specific surface area of the composite powder by 10% - 15%, providing more active sites for the subsequent water glass reaction. During the slurry storage process, due to the improved consistency of hydration initiation caused by the uniform dispersion of the early strength agent, the phenomenon of stratification and segregation is reduced, and the sedimentation rate ≤ 5% after 24 hours of storage, effectively improving the problem of early strength fluctuation caused by uneven dispersion of the early strength agent in the traditional process.

[0034] In one of the embodiments of the present invention, preferably, during the ultrasonic treatment in step 4), the frequency of the ultrasonic treatment device is 25 - 35 kHz, and the temperature is maintained at a constant temperature of 30 - 40 °C during the treatment. The frequency selection is based on the balance between the nanoparticle dispersion efficiency and the cavitation effect. At 25 kHz, the cavitation bubble collapse energy is relatively high, which is suitable for breaking large aggregates; at 35 kHz, the ultrasonic energy distribution is more uniform, which is beneficial to the dispersion of nanoparticles at the nanoscale. The ultrasonic device can be a tank-type ultrasonic processor (such as a KQ-500DE ultrasonic cleaner with a frequency of 33 kHz) or an in-line ultrasonic disperser (such as a Branson Sonifier S-450D with an adjustable frequency of 20 - 40 kHz), and a frequency adjustment module needs to be equipped. The frequency parameter is determined by testing the particle size distribution of nano-silica in the slurry, with the target of an average aggregate particle size ≤ 120 nm, to avoid excessive energy consumption or over-crushing of particles caused by too high a frequency. During the treatment, the temperature is maintained at a constant temperature of 30 - 40 °C, and the temperature control is achieved through the linkage of a heating rod and a temperature sensor built into the ultrasonic treatment device. The power of the heating rod can be selected from 500 - 1000 W, and the accuracy of the temperature sensor is ±1 °C. When the detected temperature deviates from the set value, the heating power is automatically adjusted. The constant temperature design stems from the thermodynamic requirements of the hydration reaction of water glass and cement. In the range of 30 - 40 °C, the formation rate of calcium silicate gel is the fastest, and the activity of the nanoparticle surface modifier remains stable. The temperature threshold is determined by measuring the peak of the hydration heat release of the slurry by differential scanning calorimetry (DSC) to ensure that the reaction proceeds in the optimal temperature range and to avoid unstable gel formation caused by temperature fluctuations. The installation position of the ultrasonic treatment device is on the conveying path of the mixed liquid after high-speed dispersion, and it can be connected in series between the stirring tank and the storage tank to form a continuous treatment process. A similar process can be seen in the ultrasonic dispersion process in the preparation of nanocomposites, but the present invention optimizes the synergistic effect of frequency and temperature according to the characteristics of the grouting slurry. By optimizing the ultrasonic frequency to 25 - 35 kHz and maintaining a constant temperature of 30 - 40 °C, the dispersion stability of nano-silica in the slurry is significantly improved, and the agglomeration phenomenon is reduced, providing a uniform microscopic environment for the subsequent interfacial reaction between water glass and cement. The constant temperature control promotes the full reaction of water glass hydrolysis and cement hydration products, increases the formation amount of calcium silicate gel, and improves the early strength and storage stability of the slurry. At the same time, the synergistic effect of ultrasonic cavitation and temperature improves the interfacial bonding force between particles, reduces microcracks in the hardened body, and enhances the crack resistance, solving the problems of insufficient dispersion efficiency and reaction fluctuations caused by the unoptimized frequency and temperature in traditional ultrasonic treatment.

[0035] In one embodiment of the present invention, preferably, after the ultrasonic treatment in step (4), an aging treatment is further carried out: the prepared slurry is stirred at a speed of 50-100 rpm for 1-2 hours in an environment of 25-30°C. The aging treatment needs to be carried out in an environment of 25-30°C. The temperature control can be achieved by a constant temperature stirring device, such as a stainless steel reaction kettle equipped with a water bath jacket (such as Weihai Huixin WHF type) or a vertical stirring tank with a temperature control module. The temperature of the circulating water in the jacket is adjusted by a constant temperature controller (accuracy ±1°C). The temperature range of 25-30°C is based on the synergistic effect of cement hydration heat release and the reaction of sodium silicate, which can not only promote the formation of hydrogen bonds between particles but also avoid premature setting of the slurry caused by too high temperature. The temperature threshold is determined by testing the initial setting time of the slurry to ensure that the aging process does not affect subsequent construction operations. During the aging process, the slurry is stirred at a speed of 50-100 rpm for 1-2 hours. The stirring equipment can be a paddle stirrer (such as a four-blade flat paddle) or an anchor stirrer (suitable for high-viscosity systems), and the stirring shaft is driven by a variable-frequency motor (speed accuracy ±5 rpm). The role of low-speed stirring is to promote the slow movement of particles inside the slurry, increase the contact opportunities between particles, and form a stable dispersion structure. The speed selection is based on the test of the slurry fluidity. 50 rpm is suitable for low-viscosity slurries, and 100 rpm is used for high-solid content systems. The time setting needs to ensure that the interaction force between particles is fully established, and the optimal stirring duration is optimized by measuring the sedimentation rate (target ≤3%). The assembly position of the aging treatment is downstream of the ultrasonic treatment device, and it can be directly carried out in the ultrasonic treatment tank (if the equipment has a temperature control and stirring function) or transferred to a dedicated aging tank. A similar process can be seen in the aging process of ceramic slurries, but the present invention optimizes the synergistic effect of temperature and stirring according to the characteristics of the grouting material. Through the aging treatment, the slurry completes the balance of physical and chemical interactions between particles in a low-speed stirring and constant temperature environment, reduces particle sedimentation and delamination segregation during storage, and improves the injectability during construction. At the same time, aging promotes the slow cross-linking of the hydration products on the surface of cement particles and the sodium silicate gel, increases the density of the interfacial transition zone, and improves the crack resistance of the slurry after hardening. This process solves the problem of insufficient slurry stability caused by the lack of aging in traditional preparation, provides a grouting material with more uniform performance for subsequent construction, and is suitable for engineering scenarios with high requirements for slurry storage stability and hardened body quality.

[0036] In one embodiment of the present invention, preferably, the raw materials in step 1) further include: 0.5-1.5 parts of polycarboxylate water reducer and 0.5-1.0 kg / m³ of short-cut carbon fiber. In step 2), the short-cut carbon fiber is put into a mixer together with the early strength agent, cement, silica fume, and nano-silica for dry mixing. The polycarboxylate water reducer is added to the base slurry synchronously when deionized water is added in step 3). The polycarboxylate water reducer can be a commercially available product with a solid content of 30%-40% (such as Jiangsu Sobute SP-8 high-performance water reducer), and its water reduction rate is 25%-30%; the short carbon fiber can be polyacrylonitrile-based short carbon fiber (length 3-6mm, diameter 7-10μm, tensile strength ≥3500MPa). The weighing of raw materials needs to be completed by an electronic scale (accuracy ±0.1%). The polycarboxylate water reducer is measured in liquid form, and the short carbon fiber needs to be pre-screened (aperture 1mm) to avoid agglomeration. The addition ratio is based on the balance of the need for cement particle dispersion and the fiber reinforcement effect. 0.5 parts of water reducer can reduce the surface energy of cement particles, and 1.0kg / m³ of carbon fiber can form an effective bridging network. The polycarboxylate water reducer and short carbon fiber are added to the mixer together with the early strength agent, cement, silica fume, and nano-silica for dry mixing. During the mixing process, the steric hindrance effect of the polycarboxylate water reducer inhibits particle agglomeration, and the physical interpenetration of the short carbon fiber initially forms an anti-cracking and strengthening framework. Through the steric hindrance effect of the polycarboxylate water reducer, the size of cement particle aggregates is reduced from 50μm in the traditional process to less than 20μm, the fluidity of the slurry is significantly improved, and the water consumption is reduced at the same time to maintain the balance of the water-binder ratio. The short carbon fiber forms a three-dimensional bridging structure during the hardening process of the slurry, inhibits the propagation of microcracks, and improves the anti-cracking performance. This improvement solves the problems of insufficient fluidity and hardened body cracks caused by cement particle agglomeration in the traditional slurry, enables the slurry to have better mechanical stability while maintaining high injectability, and is suitable for engineering scenarios with high requirements for the construction performance and durability of grouting materials.

[0037] In one of the embodiments of the present invention, preferably, the raw materials in step 1) further include 1-2kg / m³ of short polypropylene fiber and 1-3 parts of graphene oxide dispersion liquid, and the solid content in the graphene oxide dispersion liquid is 2-5wt%; In step 2), the short polypropylene fiber is added to the mixer together with the early strength agent, cement, silica fume, and nano-silica for dry mixing, In step 3), the graphene oxide dispersion liquid is added to the base slurry synchronously when deionized water is added in step 3). The short polypropylene fiber can be a commercially available product with a length of 6-12mm and a diameter of 18-22μm (such as PP fiber of Shandong Luyang Energy Saving Materials Co., Ltd.), and its tensile strength ≥500MPa; the graphene oxide dispersion liquid can be a water-based dispersion liquid with a solid content of 3wt% (such as XF-001 type of Nanjing Xianfeng Nano Materials Technology Co., Ltd.), or it can be prepared by oneself: ultrasonic disperse graphene oxide powder (number of layers ≤10 layers, lateral size 5-10μm) in deionized water, ultrasonic power 200-300W, time 30-60 minutes. The addition ratio is based on the balance of the need for three-dimensional network formation and the interface strengthening effect, 1kg / m 3The fibers can form a network structure with a spacing ≤ 80 μm, and 1 part of the dispersion can provide sufficient lamellar adsorption sites. The chopped polypropylene fibers and the graphene oxide dispersion are simultaneously introduced into the base slurry when deionized water is added in step 3). A three-dimensional physical network structure is formed by the chopped polypropylene fibers in the slurry, effectively inhibiting the initiation and propagation of microcracks and improving the crack resistance; the lamellar adsorption effect of graphene oxide promotes the dispersion of cement particles, increases the density of the interfacial transition zone, and improves the stability of the slurry. This improvement solves the problems of nanoparticle agglomeration and loose interfacial transition zone in traditional slurries, reduces the particle sedimentation rate during storage of the slurry, and improves the mechanical properties and durability after hardening, and is applicable to complex geological engineering scenarios with high requirements for the crack resistance and long-term stability of grouting materials.

[0038] In one of the embodiments of the present invention, preferably, the total water consumption in step 3) and step 4) is determined as follows: First, calculate the theoretical water demand according to the total specific surface area of cement and silica fume in step 1), and the calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); then adjust the actual water addition according to the water reduction rate of the polycarboxylate water reducer, the water reduction rate of the polycarboxylate water reducer is 25% - 30%, and maintain the water-binder ratio (water / binder) at 0.35 - 0.40, where the binder includes the total mass of portland cement, silica fume and nano-silica, to obtain the total water consumption. The calculation of the total water consumption is first based on the total specific surface area of cement and silica fume. The specific surface area of portland cement can be measured by the Blaine air permeability method (in line with the GB / T8074 standard, the target value ≥ 300 m² / kg), and the default value of the specific surface area of silica fume is 15000 m² / kg (industrial grade ultra-fine silica fume). The calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6), where 0.45 and 0.6 are the unit mass theoretical water demand coefficients of cement and silica fume respectively. The raw material weighing equipment can select an electronic batching scale (accuracy ±0.1%), and the masses of cement and silica fume are accurately measured to ensure that the deviation of the theoretical water demand calculation ≤ 2%. The actual water addition is adjusted according to the water reduction rate (25% - 30%) of the polycarboxylate water reducer, and maintain the water-binder ratio at 0.35 - 0.40. By combining the theoretical water demand calculation based on the specific surface area with the adjustment of the water reduction rate of the water reducer, the water-binder ratio is accurately controlled within the range of 0.35 - 0.40, solving the problem of unreasonable water consumption caused by traditional empirical mixing ratios. The fluidity of the slurry and the strength of the hardened body are synergistically optimized, avoiding particle sedimentation caused by excessive water or insufficient hydration caused by insufficient water, improving the construction adaptability and long-term mechanical properties of the slurry, and being applicable to engineering scenarios with high requirements for the performance stability of grouting materials.

[0039] In one embodiment of the present invention, preferably, the modification method of the modified nano-silica includes: dispersing nano-silica in an absolute ethanol solution to form a dispersion system with a solid-liquid ratio of 1:10, adding 3-aminopropyltriethoxysilane accounting for 1%-3% of the mass of nano-silica, magnetically stirring at 60°C - 80°C for 2 to 3 hours, then filtering and drying to obtain the modified nano-silica. The nano-silica can be a commercially available product with an average particle size of 20 - 40 nm (purity ≥ 99%, such as VK-SP15 type from Hangzhou Wanjing New Materials Co., Ltd.), and the absolute ethanol is of analytical purity (purity ≥ 99.7%). The dispersion equipment can be a magnetic stirrer (equipped with a polytetrafluoroethylene stir bar) or an ultrasonic disperser (such as a KQ-300DE type ultrasonic cleaner with a power of 300 W). First, preliminarily disperse by magnetic stirring (rotation speed 200 - 300 rpm), and then supplement with ultrasonic treatment (frequency 40 kHz) for 10 - 15 minutes to ensure the uniform dispersion of nano-particles in ethanol and avoid initial agglomeration. The selection of the solid-liquid ratio of 1:10 is based on the balance between the surface energy of nano-particles and the solvation effect. After testing, the stability of the dispersion system is the best at this ratio (no obvious sedimentation after standing for 24 hours). Add 3-aminopropyltriethoxysilane (KH-550, industrial grade, purity ≥ 95%) accounting for 1%-3% of the mass of nano-silica to the dispersion system, and magnetically stir at 60 - 80°C for 2 - 3 hours. The reaction vessel can be a three-necked flask with a reflux condenser (capacity 250 - 500 mL), control the temperature through an oil bath (accuracy ±1°C), and set the stirring speed at 300 - 400 rpm to ensure the condensation reaction between the silane coupling agent and the hydroxyl groups on the surface of nano-silica. The reaction parameters are determined by detecting the characteristic absorption peak intensity of the Si-O-Si bond through infrared spectroscopy (FT-IR). A 1% silane dosage is suitable for low surface energy requirements, and 3% is suitable for high interfacial bonding requirements, which need to be adjusted according to the dispersion target of nano-particles in the slurry. Through the modification with the silane coupling agent, the hydroxyl groups on the surface of nano-silica are replaced by silane groups, the surface energy is reduced, and the dispersibility in the slurry is significantly improved, avoiding the agglomeration problem of traditional unmodified nano-particles. The interfacial bonding force between the modified nano-particles and the cement matrix is enhanced, promoting the interactive growth of cement hydration products and sodium silicate gel, and improving the density and crack resistance of the slurry hardened body. This method solves the dispersion problem caused by the high surface energy of nano-materials, provides a key modification technology for the preparation of high-performance grouting materials, and is applicable to engineering scenarios with high requirements for the dispersibility and interfacial compatibility of nano-particles.

[0040] In one embodiment of the present invention, preferably, after the aging treatment, it further includes a microwave-assisted curing process, and the microwave-assisted curing process includes the following steps: The aged slurry is transferred into a microwave curing box and processed at a frequency of 2 - 3 GHz and a power of 300 - 600 W for 5 - 10 minutes. The microwave-assisted curing step is processed at a frequency of 2.45 GHz and a power of 300 - 600 W for 5 - 10 minutes. The frequency selection is based on the standard frequency band of industrial microwave equipment (2.45 GHz is the globally common industrial, scientific, and medical frequency band), and the power range is determined according to the slurry volume (1 - 5 L) and the heating rate requirement (the target is to increase the temperature by 5 - 10 °C per minute). The microwave curing equipment can be a box-type microwave reactor (such as the HY-3000 type from Nanjing Huiyan Microwave Instrument Co., Ltd.) or a tunnel-type microwave drying line. The former is suitable for small-batch processing in the laboratory, and the latter is suitable for industrial continuous production. The processing time is adjusted by monitoring the internal temperature of the slurry with an infrared thermometer (the target peak temperature is 60 - 70 °C) to avoid rapid evaporation of moisture caused by excessive temperature. The assembly position of the microwave-assisted curing step is the slurry conveying path after aging treatment, and a built-in microwave emitting device in the aging tank (such as a stirring tank equipped with a magnetron) or an independent microwave curing box (connected in series with the aging tank) can be directly used. The equipment needs to have a temperature feedback control function, and the slurry temperature is monitored in real time through a thermocouple sensor (accuracy ±1 °C). When the temperature exceeds 70 °C, the power is automatically reduced. A similar process can be seen in the microwave sintering process of ceramic green bodies, but the present invention optimizes the power density and processing time according to the gelling reaction characteristics of the grouting material to ensure that the microwave energy acts uniformly on polar molecules (water, sodium silicate). Through microwave-assisted curing, the electromagnetic field at a frequency of 2.45 GHz excites the polar molecules in the slurry to move at high speed, generating internal frictional heat, uniformly increasing the internal temperature of the slurry, and accelerating the cement hydration and sodium silicate gelation reactions. The microwave energy directly acts on the cementitious material particles, promoting the rapid formation of the interfacial transition zone and reducing the microcracks caused by temperature gradients in traditional curing. This process solves the problems of uneven heat transfer and slow early strength development in traditional curing processes, improves the construction efficiency of the grouting material and the density of the hardened body, and is suitable for emergency grouting projects with high requirements for early bearing capacity.

[0041] The present invention also provides a modified cement-sodium silicate slurry, which is prepared by the method according to any one of the above.

[0042] To enable those skilled in the art to better understand the technical solution of the present invention, the following embodiments are provided for further illustration: Example 1 A preparation method of a modified cement-sodium silicate slurry includes the following steps: 1) Weigh the raw materials by weight: 50 parts of portland cement, 20 parts of sodium silicate solution, 5 parts of silica fume, 3 parts of modified nano-silica, 1 part of early strength agent, and 1 kg / m of chopped polypropylene fiber 3, 1 part of graphene oxide dispersion, the solid content in the graphene oxide dispersion is 2 wt%, 0.5 of polycarboxylate superplasticizer, and 0.5 - kg / m of chopped carbon fiber 3 , the early strength agent is prepared by compounding triethanolamine and sodium sulfate according to a mass ratio of 1:2 - 1:3; 2) Put the portland cement, silica fume, nano - silica, early strength agent, chopped polypropylene fiber and chopped carbon fiber weighed in step 1) into a mixer and dry - mix for 3 minutes to uniformly mix the solid powder materials to form a composite powder. The dry - mixing process adopts two - stage treatment: first premix at a speed of 200 - 300 rpm for 2 minutes to uniformly coat the early strength agent on the cement particles, and then increase the speed to 400 / min and disperse for 1 minute.

[0043] 3) Add deionized water accounting for 60% of the total water consumption, the chopped polypropylene fiber and the graphene oxide dispersion to the composite powder obtained in step 2), and stir at a speed of 400 rpm for 8 minutes to make the water and the composite powder fully contact to form a base slurry; 4) Add the water glass solution weighed in step 1) and the remaining 40% of deionized water to the base slurry formed in step 3). First, disperse at a high speed of 800 rpm for 5 minutes to preliminarily mix the water glass solution and the base slurry evenly, and then transfer the mixed liquid to an ultrasonic treatment device and perform ultrasonic treatment at a frequency of 25 kHz and a power of 300 W for 10 minutes. During the treatment process, maintain a constant temperature of 30 °C.

[0044] After the ultrasonic treatment in step 4), an aging treatment is also carried out: stir the prepared slurry at a speed of 50 rpm in an environment of 25 °C for 1 hour.

[0045] The microwave - assisted curing process includes the following steps: Transfer the aged slurry into a microwave curing box and treat it at a frequency of 2 GHz and a power of 300 for 5 minutes. The modified cement - water glass slurry is obtained.

[0046] The modification method of modified nano - silica includes: Disperse nano - silica in an anhydrous ethanol solution to form a dispersion system with a solid - liquid ratio of 1:10, add 3 - aminopropyltriethoxysilane accounting for 1% of the mass of nano - silica, magnetically stir at 60 °C for 2 hours, then filter and dry to obtain modified nano - silica.

[0047] The total water consumption in steps 3) and 4) is determined as follows: First, calculate the theoretical water demand according to the total specific surface area of cement and silica fume in step 1). The calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); then adjust the actual water addition according to the water reduction rate of the polycarboxylate water reducer. The water reduction rate of the polycarboxylate water reducer is 25% - 30%, and the water-binder ratio (water / binder) is maintained at 0.35 - 0.40, where the binder includes the total mass of portland cement, silica fume, and nano-silica to obtain the total water consumption.

[0048] Example 2 A preparation method of a modified cement-sodium silicate slurry, comprising the following steps: 1) Weigh raw materials by weight: 60 parts of portland cement, 28 parts of sodium silicate solution, 7 parts of silica fume, 4.5 parts of modified nano-silica, 2 parts of early strength agent, 1.5 kg / m of chopped polypropylene fiber 3 and 2 parts of graphene oxide dispersion liquid. The solid content in the graphene oxide dispersion liquid is 3.5 wt%, 1 part of polycarboxylate water reducer, and 0.75 kg / m of chopped carbon fiber 3 , and the early strength agent is compounded by triethanolamine and sodium sulfate according to a mass ratio of 1:2.5; 2) Put the portland cement, silica fume, nano-silica, early strength agent, chopped polypropylene fiber, and chopped carbon fiber weighed in step 1) into a mixer and dry mix for 3 - 5 minutes to uniformly mix the solid powder materials to form a composite powder; the dry mixing process adopts two-stage treatment: first premix at a speed of 250 rpm for 2 minutes to uniformly coat the early strength agent on the cement particles, and then increase the speed to 450 rpm and disperse for 1.5 minutes.

[0049] 3) Add deionized water accounting for 65% of the total water consumption, as well as the polycarboxylate water reducer and the graphene oxide dispersion liquid to the composite powder obtained in step 2), and stir at a speed of 500 rpm for 10 minutes to fully contact the water with the composite powder to form a base slurry; 4) Add the sodium silicate solution weighed in step 1) and the remaining 35% of deionized water to the base slurry formed in step 3). First, disperse at a high speed of 700 rpm for 7 minutes to preliminarily mix the sodium silicate solution and the base slurry evenly, and then transfer the mixed solution to an ultrasonic treatment device and perform ultrasonic treatment at a frequency of 30 kHz and a power of 400 W for 12 minutes, and maintain a constant temperature of 35°C during the treatment process.

[0050] After the ultrasonic treatment in step 4), an aging treatment is also carried out: stir the prepared slurry at a speed of 75 rpm in an environment of 28°C for 1.5 hours.

[0051] The treatment in the microwave-assisted curing process includes the following steps: transferring the aged slurry into a microwave curing box, and treating it at a frequency of 2.5 GHz and a power of 450 W for 7.5 minutes to obtain a modified cement-sodium silicate slurry.

[0052] The modification method of modified nano-silica includes: dispersing nano-silica in an anhydrous ethanol solution to form a dispersion system with a solid-liquid ratio of 1:10, adding 3-aminopropyltriethoxysilane accounting for 2% of the mass of nano-silica, magnetically stirring at 70 °C for 2.5 hours, and then filtering and drying to obtain modified nano-silica.

[0053] The total water consumption in step 3) and step 4) is determined in the following way: First, calculate the theoretical water demand according to the total specific surface area of cement and silica fume in step 1), and the calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); then adjust the actual water addition amount according to the water reduction rate of the polycarboxylate water reducer. The water reduction rate of the polycarboxylate water reducer is 25%-30%, and keep the water-binder ratio (water / binder) at 0.35-0.40, where the binder includes the total mass of portland cement, silica fume and nano-silica to obtain the total water consumption.

[0054] Example 3 A preparation method of a modified cement-sodium silicate slurry includes the following steps: 1) Weigh raw materials by weight: 70 parts of portland cement, 35 parts of sodium silicate solution, 10 parts of silica fume, 6 parts of modified nano-silica, 3 parts of early strength agent, 2 kg / m of short-cut polypropylene fiber 3 、3 parts of graphene oxide dispersion liquid, the solid content in the graphene oxide dispersion liquid is 5 wt%, 1.5 parts of polycarboxylate water reducer and 1.0 kg / m of short-cut carbon fiber 3 The early strength agent is compounded by triethanolamine and sodium sulfate according to a mass ratio of 1:3; 2) Put the portland cement, silica fume, nano-silica, early strength agent, short-cut polypropylene fiber and short-cut carbon fiber weighed in step 1) into a mixer and dry mix for 5 minutes to uniformly mix the solid powder materials to form a composite powder; the dry mixing process adopts two-stage treatment: first premix at a speed of 300 rpm for 2 minutes to uniformly wrap the early strength agent on the cement particles, and then increase the speed to 500 rpm and disperse for 3 minutes.

[0055] 3) Add deionized water accounting for 70% of the total water consumption, the short-cut polypropylene fiber and the graphene oxide dispersion liquid to the composite powder obtained in step 2), and stir at a speed of 600 rpm for 12 minutes to make the water fully contact with the composite powder to form a base slurry; 4) Add the water glass solution weighed in step 1) and the remaining 30% of deionized water to the base slurry formed in step 3). First, disperse at a high speed of 1000 rpm for 8 minutes to preliminarily mix the water glass solution and the base slurry evenly. Then transfer the mixture into an ultrasonic treatment device and perform ultrasonic treatment at a frequency of 35 kHz and a power of 500 W for 15 minutes. During the treatment process, maintain a constant temperature of 40 °C.

[0056] After the ultrasonic treatment in step 4), an aging treatment is also carried out: Stir the prepared slurry at a speed of 100 rpm in an environment of 30 °C for 2 hours.

[0057] The microwave-assisted curing process includes the following steps: Transfer the aged slurry into a microwave curing box and treat it at a frequency of 3 GHz and a power of 600 W for 10 minutes. The modified cement-sodium silicate slurry is obtained.

[0058] The modification method of modified nano-silica includes: Disperse nano-silica in an anhydrous ethanol solution to form a dispersion system with a solid-liquid ratio of 1:10. Add 3-aminopropyltriethoxysilane accounting for 3% of the mass of nano-silica, and stir magnetically at 80 °C for 3 hours. Then filter and dry to obtain modified nano-silica.

[0059] The total water consumption in steps 3) and 4) is determined in the following way: First, calculate the theoretical water demand according to the total specific surface area of cement and silica fume in step 1). The calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); Then adjust the actual water addition according to the water reduction rate of the polycarboxylate water reducer. The water reduction rate of the polycarboxylate water reducer is 25%-30%, and maintain the water-binder ratio (water / binder) at 0.35-0.40, where the binder includes the total mass of portland cement, silica fume and nano-silica, to obtain the total water consumption.

[0060] Effect verification Pour the modified cement-sodium silicate slurry prepared in Examples 1-3 and cure it for 28 days, and measure its compressive strength.

[0061] Table 1 Serial number Compressive strength (MPa) Surface quality Example 1 38.9 No obvious defects Example 2 40.3 No obvious defects Example 3 39.5 No obvious defects The equipment quantities and processing scales described here are used to simplify the description of the present invention. The applications, modifications and variations of the present invention are obvious to those skilled in the art.

[0062] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the embodiments of the present invention. For those skilled in the art, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and their equivalents, the embodiments of the present invention are not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing a modified cement-water glass slurry, characterized in that: The steps include: 1) Weigh the raw materials by weight: 50-70 parts of silicate cement, 20-35 parts of water glass solution, 5-10 parts of silica fume, 3-6 parts of modified nano silicon dioxide, and 1-3 parts of early strength agent, wherein the early strength agent is prepared by compounding triethanolamine and sodium sulfate in a mass ratio of 1:2-1:3; 2) Put the silicate cement, silica fume, nano-silicon dioxide and early strength agent weighed in step 1) into a mixer and dry mix for 3-5 minutes to evenly mix the solid powders to form a composite powder; 3) adding deionized water accounting for 60%-70% of the total water consumption to the composite powder obtained in step 2), stirring at a speed of 400-600 rpm for 8-12 minutes to allow the water to fully contact the composite powder to form a base slurry; 4) Add the water glass solution weighed in step 1) and the remaining 30%-40% of deionized water to the base slurry formed in step 3), first disperse at a high speed of 800-1000 rpm for 5-8 minutes to preliminarily mix the water glass solution and the base slurry, then transfer the mixed solution to an ultrasonic treatment device, and ultrasonically treat it at a frequency of 20-40 kHz and a power of 300-500 W for 10-15 minutes to obtain a modified cement-water glass slurry.

2. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: The raw materials in step 1) also include: 0.5-1.5 parts of polycarboxylate water reducer and 0.5-1.0 kg / m³ of chopped carbon fiber; In step 2), the chopped carbon fiber, early strength agent, cement, silica fume and nano-silicon dioxide are put into a mixer for dry mixing. The polycarboxylate water reducer is added into the base slurry simultaneously with the deionized water added in step 3).

3. The method for preparing the modified cement-water glass slurry according to claim 2, characterized in that: The total water consumption in step 3) and step 4) is determined by the following method: first, the theoretical water demand is calculated according to the total specific surface area of ​​cement and silica fume in step 1), and the calculation formula is total water consumption = (cement mass × 0.45) + (silica fume mass × 0.6); then, the actual amount of water added is adjusted according to the water reduction rate of the polycarboxylate water reducer, the water reduction rate of the polycarboxylate water reducer is 25%-30%, and the water-cement ratio (water / cementitious material) is maintained at 0.35-0.40, wherein the cementitious material includes the total mass of silicate cement, silica fume and nano-silica, so as to obtain the total water consumption.

4. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: The modification method of the modified nano-silicon dioxide comprises: dispersing the nano-silicon dioxide in an anhydrous ethanol solution to form a dispersion system with a solid-liquid ratio of 1:10, adding 3-aminopropyltriethoxysilane accounting for 1%-3% of the mass of the nano-silicon dioxide, magnetically stirring at 60° C.-80° C. for 2 to 3 hours, and then filtering and drying to obtain the modified nano-silicon dioxide.

5. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: The raw materials in step 1) also include 1-2 kg / m³ of chopped polypropylene fibers and 1-3 parts of graphene oxide dispersion, wherein the solid content of the graphene oxide dispersion is 2-5 wt%; In step 2), the short-cut polypropylene fibers are put into a mixer together with an early strength agent, cement, silica fume and nano-silicon dioxide for dry mixing. In step 3), the graphene oxide dispersion is added into the base slurry simultaneously with the addition of deionized water in step 3).

6. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: During the ultrasonic treatment in step 4), the frequency of the ultrasonic treatment device is 25-35 kHz, and a constant temperature of 30-40° C. is maintained during the treatment.

7. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: After the ultrasonic treatment in step 4), an aging treatment is performed: the prepared slurry is stirred at 50-100 rpm for 1-2 hours in an environment of 25-30°C.

8. The method for preparing the modified cement-water glass slurry according to claim 7, characterized in that: After the aging treatment, a microwave-assisted curing step is also included, and the microwave-assisted curing step includes the following steps: The aged slurry is transferred to a microwave curing box and treated at a frequency of 2-3 GHz and a power of 300-600W for 5-10 minutes.

9. The method for preparing the modified cement-water glass slurry according to claim 1, characterized in that: The dry mixing process of step 2) adopts a two-stage treatment: first premix at a rotation speed of 200-300 rpm for 2 minutes to allow the early strength agent to evenly wrap the cement particles, and then increase the rotation speed to 400-500 rpm for dispersion for 1-3 minutes.

10. A modified cement-water glass slurry, characterized in that: The modified cement-water glass slurry is prepared by the method described in any one of claims 1 to 9.