Cement-based rapid repair mortar and method for producing same

Abstract

The application relates to the technical field of building materials, and particularly discloses a cement-based rapid-repairing mortar and a preparation method thereof. The mortar is composed of sulphoaluminate cement, graded quartz sand, silica fume, redispersible latex powder, calcium formate, lithium carbonate, a functional composite additive, a water reducing agent, a powder defoaming agent and mixing water. In the application, the nanosheet subjected to hydrophobization treatment is coated on the surface of the microbead, the compatibility of the nanosheet with a polymer modified cement matrix is significantly improved, the nanosheet can be used as a uniformly dispersed rigid stress skeleton, the early strength of the mortar is effectively improved, meanwhile, the core-shell structure of the composite additive can better isolate and lubricate cement and quartz sand particles during stirring, the friction and mechanical engagement between the particles are greatly reduced, the slurry under a low water-cement ratio still has excellent fluidity and uniformity, the stirring energy consumption is reduced, the homogenization time is shortened, and the construction efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a cement-based rapid repair mortar and its preparation method. Background Technology

[0002] During long-term use, concrete pavements and various concrete components are prone to damage such as cracks, potholes, and spalling due to factors such as vehicle loads and natural environment. Timely and effective repair is crucial.

[0003] Existing cement-based rapid repair mortars mostly use sulfoaluminate cement and polymer emulsion systems. However, cement, silica fume and polymer emulsions are prone to agglomeration and have poor dispersibility. In order to ensure the uniformity of mixing, long-term high-shear mixing is required, which is not only energy-intensive but also time-consuming, seriously affecting the rapid repair efficiency of concrete pavements and components, and making it difficult to meet the needs of rapid repair in actual engineering. Summary of the Invention

[0004] The purpose of this invention is to provide a cement-based rapid repair mortar and its preparation method. This repair mortar exhibits high dispersion and homogeneity, reducing mixing energy consumption and shortening mixing time. It is suitable for the rapid repair of concrete pavements and components, thereby improving repair efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A cement-based rapid repair mortar is composed of the following components in parts by weight: 100 parts of sulfoaluminate cement, 70-90 parts of 0.15-1.18mm quartz sand, 20-35 parts of 1.18-2.36mm quartz sand, 6-10 parts of silica fume, 4-6 parts of redispersible latex powder, 3-5 parts of calcium formate, 0.3-0.5 parts of lithium carbonate, 1.5-4.5 parts of functional composite additives, 1.2-1.5 parts of water-reducing agent, 0.05-0.08 parts of powdered defoamer, and 22-25 parts of mixing water;

[0007] The functional composite additive is a core-shell structured material prepared by surface composite processing of hollow glass microspheres and nanosheet silicates. The hollow glass microspheres have an average particle size of 10-100 μm and a true density of 0.2-0.6 g / cm3. The nanosheet silicates have an average sheet diameter of 1-20 μm and a thickness of 10-100 nm.

[0008] Furthermore, the preparation method of the functional composite additive includes the following steps:

[0009] S1: Mix choline chloride and urea at a mass ratio of 1.2:1 and stir at 80℃ for 40-60 min to obtain a premix. Add nanosheet silicate and hollow glass microspheres to the premix. The mass ratio of nanosheet silicate to hollow glass microspheres is 1:0.2-0.5, and the mass of nanosheet silicate is 15-25% of the mass of choline chloride. Stir at 200-400 rpm at room temperature for 30-60 min to obtain a suspension.

[0010] S2: Add silane coupling agent KH550 to the suspension obtained in step S1. The amount of silane coupling agent KH550 added is 1.5-3% of the total mass of nanosheet silicate and hollow glass microspheres. Heat to 70-85℃ and stir for 1-1.5h. Filter and separate the obtained product to obtain a solid product. Wash the solid product with ethanol and vacuum dry at 80℃ for 6-8h to obtain the functional composite additive.

[0011] Furthermore, the nanosheet silicate is nano-vermiculite or nano-mica flakes that have undergone peeling treatment. The peeling treatment is performed by wet grinding combined with ultrasonic peeling, with an ultrasonic power of 300-500W and an ultrasonic time of 30-60 minutes.

[0012] Furthermore, the total amount of quartz sand used is 90-125 parts, and the mass ratio of 0.15-1.18mm quartz sand to 1.18-2.36mm quartz sand is 2.5:1-3.5:1.

[0013] Furthermore, the redispersible latex powder is an acrylate copolymer with a solid content ≥98% and a particle size of 80-150μm.

[0014] Furthermore, the water-reducing agent is an early-strength polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of ≥30% and a slump loss of ≤10% within 30 minutes.

[0015] Furthermore, the powdered defoamer is an organosilicon-polyether composite defoamer with a particle size ≤200μm and a moisture content ≤1%.

[0016] Furthermore, the mixing water is deionized water with a conductivity ≤10μS / cm.

[0017] Furthermore, the method for preparing the cement-based rapid repair mortar is characterized by comprising the following steps:

[0018] Step 1: Weigh out the following according to the proportions: sulfoaluminate cement, all quartz sand, silica fume, redispersible latex powder, calcium formate, lithium carbonate, functional composite additives, water-reducing agent, and powdered defoamer. Put them into a forced mixer and dry mix for 30 seconds at a speed of 800-1200 r / min.

[0019] Step 2: Add all the mixing water to the mixer at once, first slowly stir at a speed of 300-500 r / min for 30 seconds, then quickly stir at a speed of 1500-2000 r / min for 90-120 seconds, and before the end of the quick stirring, vacuum degas at a vacuum degree of -0.08~-0.095 MPa for 5-10 seconds to obtain a uniform slurry;

[0020] Step 3: Pour or spray the obtained slurry onto the treated concrete substrate at an ambient temperature of 5-35℃.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. In this invention, a functional composite additive with hollow glass microspheres as the core and nanosheet silicate as the shell was prepared by a surface composite process. This composite additive successfully solves the problem of low-density hollow microspheres being easy to float and difficult to disperse in mortar systems. The hydrophobic nanosheets coated on the surface of the microspheres significantly improve their compatibility with polymer-modified cementitious matrices, enabling them to act as a uniformly dispersed rigid stress skeleton, effectively improving the early strength of the mortar. Simultaneously, during the stirring process, the core-shell structure of the composite additive allows the hollow glass microspheres to better... The nanosheet silicate isolates and lubricates cement and quartz sand particles, significantly reducing interparticle friction and mechanical interlocking. Furthermore, the nanosheet silicate ensures excellent fluidity and uniformity of the slurry even at low water-cement ratios, reducing mixing energy consumption, shortening homogenization time, and improving construction efficiency. The deep eutectic solvent formed by choline chloride and urea provides wettability and affinity to silicate and glass surfaces, helping to improve the interfacial compatibility between nanosheets and microspheres. This allows the modified nanosheets to coat the microsphere surface more uniformly and firmly, thereby enhancing the performance of the final composite additive.

[0023] 2. In this invention, the nanosheet shell layer in the functional composite additive has a very large aspect ratio and specific surface area, which generates a strong steric hindrance effect in the slurry, effectively inhibiting the flocculation and sedimentation of cement particles. The synergistic effect with the microbead core ensures the uniformity and stability of the entire system, fundamentally solving the problem of easy bleeding and segregation of fast-hardening mortar. In addition, since the surface of the nanosheets is treated with silane coupling agent, it changes from hydrophilic to hydrophobic. They can be evenly distributed in the pores and microcrack interfaces of the hardened body, forming a highly efficient hydrophobic barrier, which significantly reduces the water absorption rate and permeability of the mortar. Thus, the repair layer has good workability, volume stability and excellent long-term durability. Attached Figure Description

[0024] Figure 1 The flowchart presents a cement-based rapid repair mortar and its preparation method for the invention. Detailed Implementation

[0025] The technical solutions in the experiments of this invention will be clearly and completely described below in conjunction with the experiments of this invention. Obviously, the described experiments are only a part of the experiments of this invention, and not all of the experiments. Based on the experiments in this invention, all other experiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] It should be noted that all raw materials used in the following experiments are commercially available.

[0027] Example 1:

[0028] 1. Raw material preparation (by weight):

[0029] Sulfoaluminate cement: 100 parts;

[0030] 0.15-1.18mm continuously graded quartz sand: 75 parts;

[0031] 1.18-2.36mm continuously graded quartz sand: 25 parts (mass ratio of the two is 3:1, total amount is 100 parts);

[0032] Silica fume: 8 parts (specific surface area 20 m² / g, silica content 92%)

[0033] Acrylic copolymer redispersible latex powder: 5 parts (solid content 98%, particle size 100μm, minimum film-forming temperature 5℃).

[0034] Calcium formate: 4 parts;

[0035] Lithium carbonate: 0.4 parts;

[0036] Functional composite additive: 3.0 parts (prepared by surface composite of hollow glass microspheres and nano mica sheets, wherein the hollow glass microspheres have an average particle size of 50 μm and a true density of 0.4 g / cm³, and the nano mica sheets have an average sheet diameter of 10 μm and a thickness of 50 nm).

[0037] Early-strength polycarboxylate superplasticizer: 1.3 parts (water reduction rate 32%, slump loss 8% in 30 minutes);

[0038] Organosilicon-polyether composite powder defoamer: 0.06 parts (particle size 150μm, moisture content 0.8%).

[0039] Mixing water: 23 parts;

[0040] Preparation of functional composite additives:

[0041] S1: Choline chloride and urea were mixed at a mass ratio of 1.2:1 and stirred at 80°C for 40 min to obtain a premix. Nanosheet silicate and hollow glass microspheres were added to the premix, with a mass ratio of 1:0.2. The mass of nanosheet silicate was 15% of the mass of choline chloride. The mixture was stirred at 200 rpm for 30 min at room temperature to obtain a suspension.

[0042] S2: Add silane coupling agent KH550 to the suspension obtained in step S1. The amount of silane coupling agent KH550 added is 1.5% of the total mass of nanosheet silicate and hollow glass microspheres. Heat to 70°C and stir for 1 hour. The resulting product is filtered and separated to obtain a solid product. The solid product is washed with ethanol and vacuum dried at 80°C for 6 hours to obtain a functional composite additive.

[0043] 2. Preparation steps

[0044] Step 1: Dry mixing of dry powder materials

[0045] According to the above proportions, accurately weigh the following: 100 parts of sulfoaluminate cement, 75 parts of 0.15-1.18mm silica sand (75 parts + 25 parts of 1.18-2.36mm), 8 parts of silica fume, 5 parts of acrylate copolymer redispersible latex powder, 4 parts of calcium formate, 0.4 parts of lithium carbonate, 3.0 parts of functional composite additives, 1.3 parts of polycarboxylate superplasticizer, and 0.06 parts of powdered defoamer. Add these to a forced mixer in sequence, set the mixer speed to 1000 r / min, start the mixer to dry mix for 30 seconds, until the material is a uniform dry powder (without obvious particle agglomeration), then stop mixing.

[0046] Step 2: Slurry mixing

[0047] Pour all the mixing water (23 parts) into the forced mixer from step 1 at once. First, set the speed to 400 r / min and stir slowly for 30 seconds. Then, adjust the speed to 1800 r / min and stir quickly for 100 seconds. Five seconds before the end of the quick stirring, turn on the vacuum system of the mixer and set the vacuum degree to -0.09 MPa. Maintain the vacuum degassing for 8 seconds, and then turn off the mixer to obtain a uniform slurry.

[0048] Step 3: Construction Application

[0049] Take concrete test blocks (simulating road base), roughen them (surface roughness 5mm), and then pour the resulting slurry onto the surface of the test blocks (thickness 5cm) using a trowel at an ambient temperature of 25℃, and allow them to cure naturally.

[0050] Example 2:

[0051] 1. Raw material preparation (by weight):

[0052] Sulfoaluminate cement: 100 parts;

[0053] 0.15-1.18mm continuously graded quartz sand: 90 parts;

[0054] 1.18-2.36mm continuously graded quartz sand: 30 parts (mass ratio of the two is 3:1, total amount is 120 parts).

[0055] Silica fume: 10 parts (specific surface area 22 m2 / g, silica content 91%).

[0056] Acrylic copolymer redispersible latex powder: 6 parts (solid content 98%, particle size 120μm, minimum film-forming temperature 4℃).

[0057] Calcium formate: 5 parts;

[0058] Lithium carbonate: 0.5 parts;

[0059] Functional composite additive: 4.5 parts (prepared by surface composite of hollow glass microspheres and nano vermiculite, wherein the hollow glass microspheres have an average particle size of 100 μm and a true density of 0.6 g / cm³, and the nano vermiculite has an average flake size of 20 μm and a thickness of 100 nm).

[0060] Early-strength polycarboxylate superplasticizer: 1.5 parts (water reduction rate 30%, slump loss 10% in 30 minutes);

[0061] Organosilicon-polyether composite powder defoamer: 0.08 parts (particle size 200μm, moisture content 1%).

[0062] Mixing water: 25 parts;

[0063] Preparation of functional composite additives:

[0064] S1: Choline chloride and urea were mixed at a mass ratio of 1.2:1 and stirred at 80°C for 50 min to obtain a premix. Nanosheet silicate and hollow glass microspheres were added to the premix, with a mass ratio of nanosheet silicate to hollow glass microspheres of 1:0.3. The mass of nanosheet silicate was 20% of the mass of choline chloride. The mixture was stirred at 300 rpm for 45 min at room temperature to obtain a suspension.

[0065] S2: Add silane coupling agent KH550 to the suspension obtained in step S1. The amount of silane coupling agent KH550 added is 2% of the total mass of nanosheet silicate and hollow glass microspheres. Heat to 80°C and stir for 1.2 h. The resulting product is filtered and separated to obtain a solid product. The solid product is washed with ethanol and vacuum dried at 80°C for 7 h to obtain a functional composite additive.

[0066] 2. Preparation steps

[0067] Step 1: Dry mixing of dry powder materials

[0068] Weigh out the following according to the proportions: 100 parts of sulfoaluminate cement, 90 parts of all quartz sand (0.15-1.18mm + 30 parts of 1.18-2.36mm), 10 parts of silica fume, 6 parts of redispersible latex powder, 5 parts of calcium formate, 0.5 parts of lithium carbonate, 4.5 parts of functional composite additives, 1.5 parts of polycarboxylate superplasticizer, and 0.08 parts of powdered defoamer. Put them into a forced mixer, set the speed to 1200 r / min, dry mix for 30 seconds until the material is in a uniform dry powder state, then stop mixing.

[0069] Step 2: Slurry mixing

[0070] Pour all the mixing water (25 parts) into the mixer at once. First, stir slowly at 500 r / min for 30 seconds, then adjust the speed to 2000 r / min and stir quickly for 120 seconds. Five seconds before the end of the quick stirring, turn on the vacuum system, set the vacuum degree to -0.095 MPa, maintain degassing for 10 seconds, and then turn off the mixer to obtain a uniform slurry.

[0071] Step 3: Construction Application

[0072] Take a concrete substrate (roughed to a surface roughness of 6mm), and spray the slurry evenly onto the substrate (6cm thick) using a spraying device at an ambient temperature of 30℃, and allow it to cure naturally.

[0073] Example 3:

[0074] 1. Raw material preparation (by weight):

[0075] Sulfoaluminate cement: 100 parts;

[0076] 0.15-1.18mm continuously graded quartz sand: 70 parts;

[0077] 1.18-2.36mm continuously graded quartz sand: 20 parts (mass ratio of the two is 3.5:1, total amount is 90 parts);

[0078] Silica fume: 6 parts (specific surface area 18 m2 / g, silica content 93%).

[0079] Acrylic copolymer redispersible latex powder: 4 parts (solid content 98%, particle size 80μm, minimum film-forming temperature 3℃).

[0080] Calcium formate: 3 parts;

[0081] Lithium carbonate: 0.3 parts;

[0082] Functional composite additive: 1.5 parts (prepared by surface composite of hollow glass microspheres and nano mica sheets, wherein the hollow glass microspheres have an average particle size of 10 μm and a true density of 0.2 g / cm³, and the nano mica sheets have an average sheet diameter of 1 μm and a thickness of 10 nm).

[0083] Early-strength polycarboxylate superplasticizer: 1.2 parts (water reduction rate 35%, slump loss 5% in 30 minutes);

[0084] Organosilicon-polyether composite powder defoamer: 0.05 parts (particle size 100μm, moisture content 0.5%).

[0085] Mixing water: 22 parts;

[0086] Preparation of functional composite additives:

[0087] S1: Choline chloride and urea were mixed at a mass ratio of 1.2:1 and stirred at 80°C for 60 min to obtain a premix. Nanosheet silicate and hollow glass microspheres were added to the premix, with a mass ratio of nanosheet silicate to hollow glass microspheres of 1:0.5. The mass of nanosheet silicate was 25% of the mass of choline chloride. The mixture was stirred at 400 rpm for 60 min at room temperature to obtain a suspension.

[0088] S2: Add silane coupling agent KH550 to the suspension obtained in step S1. The amount of silane coupling agent KH550 added is 3% of the total mass of nanosheet silicate and hollow glass microspheres. Heat to 85°C and stir for 1.5 h. The resulting product is filtered and separated to obtain a solid product. The solid product is washed with ethanol and vacuum dried at 80°C for 8 h to obtain a functional composite additive.

[0089] 2. Preparation steps

[0090] Step 1: Dry mixing of dry powder materials

[0091] Weigh out the following according to the proportions: 100 parts of sulfoaluminate cement, 70 parts of all quartz sand (0.15-1.18mm + 20 parts of 1.18-2.36mm), 6 parts of silica fume, 4 parts of redispersible latex powder, 3 parts of calcium formate, 0.3 parts of lithium carbonate, 1.5 parts of functional composite additives, 1.2 parts of polycarboxylate superplasticizer, and 0.05 parts of powdered defoamer. Put them into a forced mixer, set the speed to 800 r / min, dry mix for 30 seconds until the materials are evenly mixed, and then stop mixing.

[0092] Step 2: Slurry mixing

[0093] Pour all the mixing water (22 parts) into the mixer at once. First, stir slowly at 300 r / min for 30 seconds. Then, adjust the speed to 1500 r / min and stir quickly for 90 seconds. Five seconds before the end of the quick stirring, turn on the vacuum system, set the vacuum degree to -0.08 MPa, maintain defoaming for 5 seconds, and then turn off the mixer to obtain a uniform slurry.

[0094] Step 3: Construction Application

[0095] Take a concrete base surface (roughened to a surface roughness of 4mm), and pour the grout (4cm thick) onto the base surface using a trowel at an ambient temperature of 10℃, and allow it to cure naturally.

[0096] Comparative Example 1:

[0097] Composition: exactly the same as in Example 1, but the functional composite additives are completely removed (i.e., hollow glass microspheres and nanosheet silicates are not added), and the amount of mixing water is adjusted to 23 parts (keeping the water-cement ratio unchanged).

[0098] Preparation process: After dry mixing of all dry powder materials (excluding functional compound additives), add all the mixing water directly and stir. The remaining parameters are the same as in Example 1.

[0099] Comparative Example 2:

[0100] Composition: Basically the same as in Example 1, but only an equal amount (2.0 parts) of hollow glass microspheres (without composite treatment) was added, without adding nanosheets, and 23 parts of water were mixed in;

[0101] Preparation process: Hollow glass microspheres are dry-mixed with other dry powder materials, and the remaining parameters are the same as in Example 1.

[0102] Comparative Example 3:

[0103] Composition: Basically the same as in Example 1, but only an equal amount (1.0 part) of hydrophobically treated nano-mica sheets (without composite treatment) is added, and hollow glass microspheres are not added, and 23 parts of water are mixed in.

[0104] Preparation process: The nano-mica sheets are dry-mixed with other dry powder materials, and the other parameters are the same as in Example 1.

[0105] Comparative Example 4

[0106] Composition: exactly the same as in Example 1 (i.e., containing 2.0 parts hollow glass microspheres and 1.0 parts hydrophobically treated nanomica sheets).

[0107] Preparation process: Instead of preparing functional composite additives, two materials are used as independent raw materials: nano mica sheets are dry mixed with other dry powders, and hollow glass microspheres are first premixed with mixing water to form a premixed liquid, and then added and stirred. The remaining parameters are the same as in Example 1.

[0108] Performance testing: The cement-based rapid repair mortars obtained in Examples 1, 2, 3, 1, 2, 3, and 4 were subjected to performance tests, and the test data are recorded in the table below:

[0109] index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Stirring time (until homogenization is achieved) 2.5min 3.0min 2.0min 5.0min 4.0min 4.5min 3.8min Stirring energy consumption (kJ / kg) 8.2 8.8 7.5 15.6 12.3 13.1 11.1 Flexural strength at 2 hours (MPa) 4.2 3.8 4.5 2.8 3.2 3.0 3.0 28-day water absorption rate (%) 3.5 3.8 3.2 6.5 6.3 4.6 4.5 Slurry homogeneity (coefficient of variation %) 1.2 1.5 1.0 4.8 3.5 3.2 3.2

[0110] In the performance test, the cement-based rapid repair mortars obtained from Examples 1, 2, 3, Comparative Examples 1, 2, 3 and 4 were tested. The mixing time, homogeneity and mixing energy consumption were tested with reference to standard GB / T25181-2019, and the flexural strength and water absorption were tested with reference to standard JGJ / T 70-2009.

[0111] It is evident that the homogenization mixing time for Examples 1-3 was only 2.0-3.0 min, with an energy consumption of 7.5-8.8 kJ / kg, while Comparative Examples 1-4 required 3.8-5.0 min and 11.1-15.6 kJ / kg, respectively. This indicates that the functional composite structure disperses rapidly in the slurry and acts as a lubricant, significantly reducing mixing resistance. The 2-hour flexural strength of Examples 1-3 was 3.8-4.5 MPa, averaging 30-60% higher than that of Comparative Examples 1-4, demonstrating that the functional composite structure can significantly accelerate the early hydration of sulfoaluminate cement. Furthermore, the 28-day water absorption rate of Examples 1-3 was 3.2-3.8%, while that of Comparative Examples 1-4 was as high as 4.5-6.5%. Hollow microspheres introduce closed pores to reduce bulk density, and nanosheet silicates form a dense layer on the surface of the microspheres, refining the pore size and blocking interconnecting pores, significantly reducing water absorption. Meanwhile, Examples 1-3 exhibit excellent homogeneity (coefficient of variation 1.0%-1.5%), indicating that the functional composite additive can be uniformly and stably dispersed in the slurry. The homogeneity of all comparative examples is significantly worse (>3.2%). Even with the addition of functional additives through physical mixing, the floating problem of hollow glass microspheres is not solved, and the addition of nanosheets even exacerbates the non-uniformity of particle distribution. This demonstrates the importance of modifying the surface of microspheres with nanosheets to solve compatibility and dispersibility problems.

[0112] Although individual hollow glass microspheres (Comparative Example 2) or individual nanosheets (Comparative Example 3) can improve performance to some extent, they are not as good as the examples. Although Comparative Example 4 contains two components at the same time, it is not pre-composite, resulting in uneven dispersion. Physical blending cannot exert a synergistic effect and must be chemically-physically coated to form a core-shell structure.

[0113] Therefore, by comparing and analyzing the relevant data in the table, it can be seen that Examples 1-3, through the use of functional composite additives, simultaneously achieved low-energy-consumption rapid mixing (2.0-3.0 min), high early strength (3.8-4.5 MPa), excellent homogeneity (coefficient of variation ≤1.5%), and low water absorption (≤3.8%). Compared with the comparative examples lacking single or composite processes, all performance characteristics were significantly deteriorated. The cement-based rapid repair mortar prepared by this invention satisfies excellent homogeneity, low mixing energy consumption, and also has high early strength and low water absorption, significantly improving repair efficiency. This indicates that the cement-based rapid repair mortar and its preparation method provided by this invention have a broader market prospect and are more suitable for promotion.

[0114] In the description of this specification, references to terms such as "an experiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that experiment or example is included in at least one experiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same experiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more experiments or examples.

[0115] The preferred experiments disclosed above are merely illustrative of the invention. These preferred experiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these experiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize it. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A cement-based rapid repair mortar, characterized in that, It is composed of the following components in parts by weight: 100 parts of sulfoaluminate cement, 70-90 parts of 0.15-1.18mm quartz sand, 20-35 parts of 1.18-2.36mm quartz sand, 6-10 parts of silica fume, 4-6 parts of redispersible latex powder, 3-5 parts of calcium formate, 0.3-0.5 parts of lithium carbonate, 1.5-4.5 parts of functional composite additives, 1.2-1.5 parts of water-reducing agent, 0.05-0.08 parts of powdered defoamer, and 22-25 parts of mixing water; The functional composite additive is a core-shell structured material prepared by surface composite processing of hollow glass microspheres and nanosheet silicates. The hollow glass microspheres have an average particle size of 10-100 μm and a true density of 0.2-0.6 g / cm3. The nanosheet silicates have an average sheet diameter of 1-20 μm and a thickness of 10-100 nm.

2. The cement-based rapid repair mortar according to claim 1, characterized in that, The preparation method of the functional composite additive includes the following steps: S1: Mix choline chloride and urea at a mass ratio of 1.2:1 and stir at 80℃ for 40-60 min to obtain a premix. Add nanosheet silicate and hollow glass microspheres to the premix. The mass ratio of nanosheet silicate to hollow glass microspheres is 1:0.2-0.5, and the mass of nanosheet silicate is 15-25% of the mass of choline chloride. Stir at 200-400 rpm at room temperature for 30-60 min to obtain a suspension. S2: Add silane coupling agent KH550 to the suspension obtained in step S1. The amount of silane coupling agent KH550 added is 1.5-3% of the total mass of nanosheet silicate and hollow glass microspheres. Heat to 70-85℃ and stir for 1-1.5h. Filter and separate the obtained product to obtain a solid product. Wash the solid product with ethanol and vacuum dry at 80℃ for 6-8h to obtain the functional composite additive.

3. The cement-based rapid repair mortar according to claim 2, characterized in that, The nanosheet silicate is nano-vermiculite or nano-mica flakes that have undergone peeling treatment. The peeling treatment is carried out by wet grinding combined with ultrasonic peeling, with an ultrasonic power of 300-500W and an ultrasonic time of 30-60 minutes.

4. The cement-based rapid repair mortar according to claim 1, characterized in that, The total amount of quartz sand used is 90-125 parts, and the mass ratio of 0.15-1.18mm quartz sand to 1.18-2.36mm quartz sand is 2.5:1-3.5:

1.

5. The cement-based rapid repair mortar according to claim 1, characterized in that, The redispersible latex powder is an acrylate copolymer with a solid content of ≥98% and a particle size of 80-150μm.

6. The cement-based rapid repair mortar according to claim 1, characterized in that, The water-reducing agent is an early-strength polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of ≥30% and a slump loss of ≤10% within 30 minutes.

7. The cement-based rapid repair mortar according to claim 1, characterized in that, The powdered defoamer is an organosilicon-polyether composite defoamer with a particle size ≤200μm and a moisture content ≤1%.

8. The cement-based rapid repair mortar according to claim 1, characterized in that, The mixing water is deionized water with a conductivity ≤10μS / cm.

9. A method for preparing cement-based rapid repair mortar as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Weigh out the following according to the proportions: sulfoaluminate cement, all quartz sand, silica fume, redispersible latex powder, calcium formate, lithium carbonate, functional composite additives, water-reducing agent, and powdered defoamer. Put them into a forced mixer and dry mix for 30 seconds at a speed of 800-1200 r / min. Step 2: Add all the mixing water to the mixer at once, first slowly stir at a speed of 300-500 r / min for 30 seconds, then quickly stir at a speed of 1500-2000 r / min for 90-120 seconds, and before the end of the quick stirring, vacuum degas at a vacuum degree of -0.08~-0.095 MPa for 5-10 seconds to obtain a uniform slurry; Step 3: Pour or spray the obtained slurry onto the treated concrete substrate at an ambient temperature of 5-35℃.

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