A fast-hardening concrete crack repairing agent and a preparation method thereof

Abstract

The application relates to the technical field of concrete crack repairing, and particularly discloses a fast-hardening concrete crack repairing agent and a preparation method thereof. The fast-hardening concrete crack repairing agent is prepared from the following raw materials in parts by weight: 45-55 parts of sulphoaluminate cement, 10-15 parts of silica ash, 12-18 parts of metakaolin, 5-8 parts of double-metal composite crystal seeds, 10-15 parts of double-shell nano hard gypsum, 2-4 parts of magnesium oxide, 0.5-1 part of polypropylene fiber, 0.5-0.8 part of water reducing agent and 15-20 parts of water. The double-metal composite crystal seeds are composite crystal cores co-doped with zirconium and strontium elements. The double-shell nano hard gypsum is composed of inner core nano hard gypsum, middle layer aluminium sulfate early strength phase and outer layer mesoporous SiO2 shell. The fast-hardening concrete crack repairing agent has the advantages of short setting time, high early strength and excellent interface bonding performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete crack repair, and more particularly to a fast-hardening concrete crack repair agent and a preparation method thereof. BACKGROUND

[0002] In the field of civil engineering, concrete structures are prone to cracking due to factors such as long-term load bearing, environmental erosion, and temperature changes. These cracks not only reduce the overall integrity and durability of the structure, but also can lead to problems such as steel corrosion and leakage, seriously threatening the safety and service life of the project. Therefore, concrete crack repair technology is a key link to ensure structural safety, and the performance of crack repair agents, as the core material of this technology, directly determines the quality of the repair effect. Currently, crack repair agents have been widely used in the repair and reinforcement of various concrete projects such as buildings, bridges, tunnels, and water conservancy, restoring the mechanical properties and functional performance of concrete structures through filling, bonding, and reinforcement.

[0003] In related technologies, a patent application with publication number CN118167075A discloses a method for repairing concrete. The method includes crack detection and marking, crack internal and surface cleaning, preparation of repair materials, crack repair and construction, and crack surface treatment. The repair material includes cement, sand, special gel, additives, and bonding agents. By adding gel materials to the repair material, it has good adhesion and durability, and the repaired concrete can achieve the appearance and performance matching the original concrete. The formula of the repair material is simple and easy to mix, reducing the complexity and difficulty of the operation process.

[0004] However, the above-mentioned repair material still has obvious defects in actual application: the repair material in related technologies uses ordinary cement as the main cementitious material, and its hydration reaction depends on the slow reaction of cement clinker minerals with water. The initial setting time at room temperature often exceeds 5 hours, and the final setting time is up to 12 hours or more. And the formula lacks targeted early strength activator components, and the additives have limited effect on the hydration process, which cannot accelerate the rapid generation and setting hardening of the hydration products in the cementitious system. This leads to the difficulty of forming effective strength in the repaired cracks in a short time, and the inability to meet the rapid bearing demand in emergency repair scenarios, which seriously prolongs the project recovery period. Therefore, how to develop a fast-hardening concrete crack repair agent with short setting time, high early strength, and excellent interfacial adhesion performance has become a key technical problem to be solved in the current field. SUMMARY

[0005] In order to provide a fast-hardening concrete crack repair agent with short setting time, high early strength, and excellent interfacial adhesion performance, the present application provides a fast-hardening concrete crack repair agent and a preparation method thereof.

[0006] The application provides a fast-hardening concrete crack repairing agent adopting the following technical scheme:

[0007] A fast-hardening concrete crack repairing agent comprises the following raw materials in parts by weight:

[0008] 45-55 parts of sulphoaluminate cement;

[0009] 10-15 parts of silica fume;

[0010] 12-18 parts of metakaolin;

[0011] 5-8 parts of bimetallic composite seed crystal;

[0012] 10-15 parts of double-shell nano hard gypsum;

[0013] 2-4 parts of magnesium oxide;

[0014] 0.5-1 part of polypropylene fiber;

[0015] 0.5-0.8 part of water reducing agent;

[0016] 15-20 parts of water;

[0017] The bimetallic composite seed crystal is a composite crystal nucleus co-doped with zirconium and strontium elements;

[0018] The double-shell nano hard gypsum is composed of an inner core nano hard gypsum, a middle layer aluminum sulfate early strength phase and an outer layer mesoporous SiO2 shell.

[0019] By adopting the above technical scheme, the sulphoaluminate cement is used as the main cementitious material, and the hydration reaction is fast, thereby providing a basis for the rapid setting and hardening of the repairing agent. The silica fume and the metakaolin have high activity, can fill pores and enhance compactness. The bimetallic composite seed crystal (co-doped with zirconium and strontium elements) is used as the fast-hardening core, Zr 4+ reduces the ettringite nucleation barrier and improves the early generation rate of AFt; Sr 2+ makes the Sr-AFt crystal more stable and solves the problem of easy decomposition of traditional ettringite in the later period. The synergistic effect of the two ions makes the initial setting time of the repairing agent break through 2h, and the strength continues to grow. The double-shell nano hard gypsum releases aluminum sulfate and C3A in the early stage to generate ettringite, and the inner core hard gypsum continuously releases SO4 2- in the later period, thereby ensuring the continuous growth of the strength. The magnesium oxide adjusts the hydration heat, the polypropylene fiber enhances the crack resistance, the water reducing agent improves the workability, and water provides the reaction medium. The synergistic effect of the components effectively solves the problems of long setting time and low early strength of the existing repairing materials, and realizes the effects of short setting time, high early strength and excellent interface bonding performance.

[0020] Optionally, the bimetallic composite seed is prepared by the following method:

[0021] Zirconium nitrate and strontium nitrate are dissolved in deionized water, ammonia water is added dropwise to adjust the pH to 10, and the product is subjected to hydrothermal reaction at 160-180℃ for 8-10h, followed by centrifugal washing, vacuum drying at 50-60℃, and ball milling to obtain the bimetallic composite seed.

[0022] By using the above technical solution, zirconium nitrate and strontium nitrate are dissolved in deionized water, ammonia water is added dropwise to adjust the pH to 10.5, and then hydrothermal reaction is carried out. Under this condition, zirconium and strontium elements can fully react to form a co-doped composite crystal nucleus. The high temperature and high pressure environment provided by the hydrothermal reaction is conducive to the growth of the crystal and the perfection of the crystal form, so that the generated seed has better activity and stability. After centrifugal washing to remove impurities, vacuum drying to prevent oxidation and agglomeration, and ball milling to obtain bimetallic composite seed with uniform particle size. This preparation method ensures the quality and performance of the bimetallic composite seed, so that it can better play the role of reducing the nucleation potential barrier of ettringite, improving the early generation rate, and forming stable Sr-AFt crystals in the repair agent, thereby helping to shorten the setting time of the repair agent and improve the early strength.

[0023] Optionally, the mass ratio of zirconium nitrate, strontium nitrate and deionized water is 1:(0.1-0.3):(5-8).

[0024] By using the above technical solution, the above mass ratio can ensure that zirconium and strontium elements are uniformly dispersed in the solution and fully react in the hydrothermal reaction to generate bimetallic composite seeds with excellent performance, thereby achieving the best effect on the setting time and strength development of the repair agent and meeting the requirements of rapid repair and long-term stability.

[0025] Optionally, the double-shell nano-hard gypsum is prepared by the following method:

[0026] Nano-hard gypsum is dispersed in an aluminum sulfate solution, ultrasonic treatment is performed for 30-50min, then a hexadecyl trimethyl ammonium bromide-ethanol-ammonia water mixture is added, followed by the addition of ethyl silicate, stirring under nitrogen protection for 10-12h, and calcination at 500-550℃ for 2-4h to obtain double-shell nano-hard gypsum.

[0027] By using the above technical solution, the double-shell structure formed by the above preparation method has unique advantages. The outer mesoporous SiO2 initially blocks too fast dissolution, the middle layer of aluminum sulfate preferentially releases and reacts with C3A to generate ettringite in the early stage, solving the problem of insufficient SO4 2— release in the early stage, and the inner core of hard gypsum continuously releases SO4 2— in the later stage, ensuring continuous strength growth and effectively improving the performance of the repair agent.

[0028] Optionally, the concentration of the aluminum sulfate solution is 0.1-0.3 mol / L, and the mass ratio of the nano-hard gypsum to the aluminum sulfate solution is 1:(5-7).

[0029] Optionally, in the cetyltrimethylammonium bromide-ethanol-ammonia water mixed solution, the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia water is 1:(6-10):(0.5-1.5); and the addition amount of the cetyltrimethylammonium bromide-ethanol-ammonia water mixed solution is 8-12 times the mass of the nano-hard gypsum.

[0030] Optionally, the addition amount of the ethyl silicate is 30%-50% of the mass of the nano-hard gypsum.

[0031] Optionally, the heating rate in the calcination process is 5-10℃ / min, and the material is naturally cooled to room temperature after calcination, and then is reserved after being sieved through a 300-400 mesh screen.

[0032] By using the above technical solution, the above heating rate can ensure that the double-shell nano-hard gypsum gradually stabilizes in the calcination process, and avoid structure damage caused by too fast heating. Naturally cooling to room temperature can uniformly release the internal stress of the material, and prevent cracks and other defects caused by rapid cooling. Sieving through a 300-400 mesh screen can remove large-particle impurities and agglomerates, and obtain double-shell nano-hard gypsum with uniform particle size. These conditions work together to ensure the quality and performance of the double-shell nano-hard gypsum, so that it can better play the role of regulating SO4 2— release, promoting the generation of ettringite, etc. in the repair agent, thereby improving the setting time and strength development performance of the repair agent, and meeting the needs of rapid repair of concrete cracks.

[0033] Optionally, the length of the polypropylene fiber is 6-12 mm, and the diameter is 20-30 μm.

[0034] The application also provides a preparation method of the fast-hardening concrete crack repair agent, which uses the following technical solution:

[0035] A preparation method of a fast-hardening concrete crack repair agent, which includes the following steps:

[0036] S1, adding sulfoaluminate cement, silica fume, metakaolin, double-metal composite seed crystal, double-shell nano-hard gypsum, magnesium oxide and polypropylene fiber into a stirrer in sequence, and stirring at 1000-1200 rpm for 8-12 min to obtain dry mixture;

[0037] S2, adding water reducing agent and water to the dry mixture, and adjusting the stirring speed to 600-800 rpm for 3-5 min to obtain the fast-hardening concrete crack repair agent.

[0038] The components of the repair agent prepared by the method can fully play a role, realize the effects of short setting time, high early strength and excellent interface bonding performance, and meet the technical requirements of rapid repair of concrete cracks.

[0039] In summary, the present application has the following beneficial effects:

[0040] 1. The present application solves the problems of slow setting and insufficient early strength of traditional repair agents by innovative design of a synergistic system of bimetallic composite seeds and double-shell nano hard gypsum. The zirconium element in the bimetallic composite seeds can accelerate the nucleation process of ettringite crystals, significantly shortening the setting time; the strontium element enhances the stability of the crystal structure, preventing late strength decay. The double-shell nano hard gypsum releases sulfate ions early to promote the formation of ettringite, achieving rapid hardening through its unique layered structure; it continuously releases sulfate ions later to ensure long-term stable growth of strength. As a base material, sulphoaluminate cement provides a fast-hardening basis, silica fume and metakaolin enhance strength, magnesium oxide compensates for shrinkage, and polypropylene fiber inhibits cracks. Under the synergistic action of multiple components, the repair agent can form sufficient strength in a short time, solving the problem of prolonged project cycle caused by slow setting of traditional materials, and is especially suitable for emergency repair scenes.

[0041] 2. The present application significantly improves the interface bonding effect of the repair agent and the concrete matrix by precisely regulating the structure and performance of key components. The bimetallic composite seeds promote the preferential growth of ettringite at the interface, forming a tight anchoring structure; the released sulfate ions of the double-shell nano hard gypsum react with the matrix components to enhance the chemical bonding force. Silica fume and metakaolin generate gel through pozzolanic reaction, penetrate and fill the matrix pores, forming a "nanobridge" effect; polypropylene fibers span the interface microcracks, strengthening the mechanical interlocking effect. These designs collectively enhance the interface integrity of the repair layer and the original concrete, avoiding the common problems of interface peeling and hollowing of traditional repair agents. At the same time, the hydration products of magnesium oxide form a dense protective layer, delaying the penetration of aggressive ions, and significantly improving the long-term durability of the repaired structure. DETAILED DESCRIPTION

[0042] The present application is further described in detail below in conjunction with examples.

[0043] Preparation example of bimetallic composite seeds

[0044] Preparation example 1

[0045] The bimetallic composite seeds are prepared by the following method:

[0046] Dissolve 1 kg of zirconium nitrate and 0.1 kg of strontium nitrate in 5 kg of water, add ammonia water to adjust the pH to 10, react at 160℃ for 8h, and then centrifuge and wash the product. Vacuum drying is carried out at 50℃, and then ball milling is carried out to obtain bimetallic composite seeds.

[0047] Preparation Example 2

[0048] The bimetallic composite seed was prepared by the following method:

[0049] Dissolve 1 kg of zirconium nitrate and 0.2 kg of strontium nitrate in 6.5 kg of water, adjust the pH to 10 by adding ammonia water dropwise, react at 170°C for 9 h, and then vacuum dry the product at 55°C after centrifugal washing, and then ball mill to obtain the bimetallic composite seed.

[0050] Preparation Example 3

[0051] The bimetallic composite seed was prepared by the following method:

[0052] Dissolve 1 kg of zirconium nitrate and 0.3 kg of strontium nitrate in 8 kg of water, adjust the pH to 10 by adding ammonia water dropwise, react at 180°C for 10 h, and then vacuum dry the product at 60°C after centrifugal washing, and then ball mill to obtain the bimetallic composite seed.

[0053] Preparation Example of Double-shell Nanometer Hard Gypsum

[0054] Preparation Example 4

[0055] The double-shell nanometer hard gypsum was prepared by the following method:

[0056] Dissolve 1 kg of nanometer hard gypsum in 5 kg of 0.1 mol / L aluminum sulfate solution, ultrasonic treat for 30 min, then add 8 kg of cetyltrimethylammonium bromide-ethanol-ammonia water mixed solution, the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia water in the cetyltrimethylammonium bromide-ethanol-ammonia water mixed solution is 1:6:0.5, then add 0.3 kg of ethyl silicate, stir for 10 h under nitrogen protection, and then calcine at 500°C for 4 h, the heating rate during calcination is 5°C / min, and then naturally cool to room temperature after calcination, and then pass through a 300 mesh screen to obtain the double-shell nanometer hard gypsum.

[0057] Preparation Example 5

[0058] The double-shell nanometer hard gypsum was prepared by the following method:

[0059] 1 kg nano-hard gypsum was dispersed in 6 kg aluminum sulfate solution with concentration of 0.2 mol / L, and then ultrasonic treatment was performed for 40 min. Then 10 kg of cetyltrimethylammonium bromide-ethanol-ammonia mixed solution was added, in which the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia was 1:8:1. Then 0.4 kg of ethyl silicate was added, and stirring was performed under nitrogen protection for 11 h. Calcination was performed at 530 ℃ for 3 h, in which the heating rate was 8 ℃ / min. After calcination, natural cooling was performed to room temperature, and then 300 mesh screen was used to obtain double-shell nano-hard gypsum.

[0060] Preparation Example 6

[0061] Double-shell nano-hard gypsum was prepared by the following method:

[0062] 1 kg nano-hard gypsum was dispersed in 7 kg aluminum sulfate solution with concentration of 0.3 mol / L, and then ultrasonic treatment was performed for 50 min. Then 12 kg of cetyltrimethylammonium bromide-ethanol-ammonia mixed solution was added, in which the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia was 1:10:1.5. Then 0.5 kg of ethyl silicate was added, and stirring was performed under nitrogen protection for 12 h. Calcination was performed at 550 ℃ for 2 h, in which the heating rate was 10 ℃ / min. After calcination, natural cooling was performed to room temperature, and then 400 mesh screen was used to obtain double-shell nano-hard gypsum.

[0063] Preparation Example 7

[0064] Silicon dioxide coated nano-hard gypsum was prepared by the following method:

[0065] 1 kg nano-hard gypsum was dispersed in 12 kg cetyltrimethylammonium bromide-ethanol-ammonia mixed solution, in which the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia was 1:10:1.5. Then 0.5 kg of ethyl silicate was added, and stirring was performed under nitrogen protection for 12 h. Calcination was performed at 550 ℃ for 2 h, in which the heating rate was 10 ℃ / min. After calcination, natural cooling was performed to room temperature, and then 400 mesh screen was used to obtain silicon dioxide coated nano-hard gypsum.

[0066] Example

[0067] Example 1

[0068] A fast hardening type concrete crack repair agent, raw material components and amounts of which are shown in Table 1, wherein the bimetallic composite seed crystal is the bimetallic composite seed crystal prepared in Preparation Example 1, the double-shell nano-hard gypsum is the bimetallic composite seed crystal prepared in Preparation Example 4, the average length of the polypropylene fiber is 6 mm, the average diameter is 20 μm, and the water reducing agent is a polycarboxylic acid type super early strength water reducing agent.

[0069] A fast hardening type concrete crack repair agent is prepared by the following method:

[0070] S1, the sulphoaluminate cement, silica fume, metakaolin, bimetallic composite seed crystal, double-shell nano-hard gypsum, magnesium oxide, and polypropylene fiber are sequentially added to a stirrer, and stirred at 1000 rpm for 12 min to obtain a dry mixture;

[0071] S2, the water reducing agent and water are added to the dry mixture, and the stirring speed is adjusted to 600 rpm for 3 min to obtain the fast hardening type concrete crack repair agent.

[0072] Example 2

[0073] A fast hardening type concrete crack repair agent, raw material components and amounts of which are shown in Table 1, wherein the bimetallic composite seed crystal is the bimetallic composite seed crystal prepared in Preparation Example 2, the double-shell nano-hard gypsum is the bimetallic composite seed crystal prepared in Preparation Example 5, the average length of the polypropylene fiber is 10 mm, the average diameter is 25 μm, and the water reducing agent is a polycarboxylic acid type super early strength water reducing agent.

[0074] A fast hardening type concrete crack repair agent is prepared by the following method:

[0075] S1, the sulphoaluminate cement, silica fume, metakaolin, bimetallic composite seed crystal, double-shell nano-hard gypsum, magnesium oxide, and polypropylene fiber are sequentially added to a stirrer, and stirred at 1100 rpm for 10 min to obtain a dry mixture;

[0076] S2, the water reducing agent and water are added to the dry mixture, and the stirring speed is adjusted to 700 rpm for 4 min to obtain the fast hardening type concrete crack repair agent.

[0077] Example 3

[0078] A fast hardening type concrete crack repair agent, raw material components and amounts of which are shown in Table 1, wherein the bimetallic composite seed crystal is the bimetallic composite seed crystal prepared in Preparation Example 3, the double-shell nano-hard gypsum is the bimetallic composite seed crystal prepared in Preparation Example 6, the average length of the polypropylene fiber is 12 mm, the average diameter is 30 μm, and the water reducing agent is a polycarboxylic acid type super early strength water reducing agent.

[0079] A fast hardening type concrete crack repair agent is prepared by the following method:

[0080] S1, add sulphoaluminate cement, silica fume, metakaolin, bimetallic composite seed crystal, double-shell nano-hard gypsum, magnesium oxide, polypropylene fiber into a stirring machine in turn, stir at 1200 rpm for 8 min to obtain dry mixture;

[0081] S2, add water reducing agent and water to the dry mixture, adjust the stirring speed to 800 rpm and stir for 5 min to obtain the fast-hardening concrete crack repair agent.

[0082] Table 1 Raw material components and amounts (kg) of the repair agent in examples 1-3

[0083]

[0084] Example 4

[0085] A fast-hardening concrete crack repair agent, which is different from example 1 in that the length of the polypropylene fiber in this example is 20 mm and the average diameter is 30 μm.

[0086] Comparative example

[0087] Comparative example 1

[0088] A fast-hardening concrete crack repair agent, which is different from example 1 in that silicate cement is used instead of sulphoaluminate cement in this comparative example.

[0089] Comparative example 2

[0090] A fast-hardening concrete crack repair agent, which is different from example 1 in that bimetallic composite seed crystal and double-shell nano-hard gypsum are not added in this comparative example, and the difference is made up by sulphoaluminate cement and silica fume.

[0091] Comparative example 3

[0092] A fast-hardening concrete crack repair agent, which is different from example 1 in that bimetallic composite seed crystal is not added in this comparative example, and the difference is made up by double-shell nano-hard gypsum.

[0093] Comparative example 4

[0094] A fast-hardening concrete crack repair agent, which is different from example 1 in that double-shell nano-hard gypsum is not added in this comparative example, and the difference is made up by 3 kg of bimetallic composite seed crystal and 7 kg of sulphoaluminate cement.

[0095] Comparative example 5

[0096] A fast-hardening concrete crack repair agent, which is different from example 1 in that the double-shell nano-hard gypsum is replaced by an equal amount of silica-coated nano-hard gypsum prepared in preparation example 7.

[0097] Comparative example 6

[0098] A fast hardening type concrete crack repair agent, which is different from Example 1 in that no magnesium oxide is added in the present comparative example, and the difference is made up by sulphoaluminate cement.

[0099] Performance test

[0100] 1. According to the Cement Concrete Mixture Setting Test Method (T0527-2005), the initial setting time and final setting time of the above repair agent were detected, and the test results are shown in Table 2.

[0101] 2. The early strength of the above repair agent was detected by the Cube Compression Test, and the test results are shown in Table 2 according to the Cement Mortar Strength Test Method (GB / T17671).

[0102] 3. The bonding performance of the repair agent and the concrete matrix was detected by the Pull-out Test according to the Engineering Structure Reinforcement Material Safety Identification Technical Specification (GB / T50728-2011), and the test results are shown in Table 2.

[0103] Table 2 Test Results

[0104]

[0105] The initial setting time of the repair agent of Examples 1-4 is 660-730s, and the final setting time is 32-35min. This is due to the synergistic effect of the double-metal composite seed and the double-shell nano-hard gypsum, the double-metal composite seed accelerates the nucleation of ettringite crystals, the double-shell nano-hard gypsum early releases sulfate ions to promote the formation of ettringite, and the sulphoaluminate cement provides a fast hardening basis, which shortens the setting time together.

[0106] In Comparative Example 1, portland cement is used instead of sulphoaluminate cement, the initial setting time is prolonged to 1080s, and the final setting time is prolonged to 46min. Because the hydration reaction of ordinary portland cement is slow, the setting time is prolonged. In Comparative Example 2, no double-metal composite seed and double-shell nano-hard gypsum are added, the initial setting time is greatly prolonged to 1440s, and the final setting time is prolonged to 58min. Without the key early strength activating components, it is impossible to accelerate the generation and setting hardening of the hydration products of the cementitious system. In Comparative Examples 3-5, the double-metal composite seed, the double-shell nano-hard gypsum or the nano-hard gypsum coated with silicon dioxide is respectively absent, and the initial setting and final setting times are longer than those of the examples. It is shown that the double-metal composite seed and the double-shell nano-hard gypsum are indispensable for shortening the setting time, and the double-shell structure has unique advantages. In Comparative Example 6, no magnesium oxide is added, the initial setting time is prolonged to 760s, and the final setting time is prolonged to 36min. Magnesium oxide can adjust the hydration heat, and also has a certain influence on the setting time.

[0107] The compressive strength of the embodiments 1-4 is 36.8-42.5 MPa. The multi-component synergistic effect, the strontium element in the bimetallic composite seed enhances the stability of the crystal structure, the double-shell nano hard gypsum continuously releases sulfate ions in the later stage to guarantee the strength growth, the dense structure of silica ash and metakaolin improves the strength, and magnesium oxide compensates for shrinkage.

[0108] The adhesive strength of the embodiments 1-4 is 2.5-2.9 MPa. The bimetallic composite seed promotes the preferential growth of ettringite at the interface to form an anchoring structure, the sulfate ions released by the double-shell nano hard gypsum enhance the chemical bonding force, the "nano bridging" effect of silica ash and metakaolin, and the polypropylene fiber strengthens the mechanical interlocking effect. Therefore, the repair agent provided by the present application has strong interfacial adhesion and can be better applied to concrete repair operations.

[0109] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A fast-hardening type concrete crack repair agent, characterized by, The raw materials include the following weight parts: Sulfoaluminate cement 45-55 parts; Silica fume 10-15 parts; Metakaolin 12-18 parts; Bimetallic composite seed crystal 5-8 parts; Double-shell nano hard gypsum 10-15 parts; Magnesium oxide 2-4 parts; Polypropylene fiber 0.5-1 part; Water reducing agent 0.5-0.8 part; Water 15-20 parts; The bimetallic composite seed crystal is prepared by the following method: Zirconium nitrate and strontium nitrate are dissolved in deionized water, ammonia water is added dropwise to adjust the pH to 10, and the product is reacted at 160-180℃ for 8-10h, then washed by centrifugation, vacuum dried at 50-60℃, and then ball milled to obtain the bimetallic composite seed crystal; The double-shell nano hard gypsum is prepared by the following method: Nano hard gypsum is dispersed in an aluminum sulfate solution, ultrasonically treated for 30-50min, then a cetyltrimethylammonium bromide-ethanol-ammonia water mixture is added, followed by the addition of ethyl silicate, and stirred under nitrogen protection for 10-12h, then calcined at 500-550℃ for 2-4h to obtain the double-shell nano hard gypsum.

2. The fast hardening concrete crack repair agent according to claim 1, characterized in that: The mass ratio of the zirconium nitrate, strontium nitrate and deionized water is 1:(0.1-0.3):(5-8).

3. The fast hardening concrete crack repair agent according to claim 1, characterized in that: The concentration of the aluminum sulfate solution is 0.1-0.3mol / L, and the mass ratio of the nano hard gypsum to the aluminum sulfate solution is 1:(5-7).

4. The fast hardening concrete crack repair agent according to claim 1, characterized in that: In the cetyltrimethylammonium bromide-ethanol-ammonia water mixture, the mass ratio of cetyltrimethylammonium bromide, ethanol and ammonia water is 1:(6-10):(0.5-1.5); and the addition amount of the cetyltrimethylammonium bromide-ethanol-ammonia water mixture is 8-12 times the mass of the nano hard gypsum.

5. The fast hardening concrete crack repair agent according to claim 1, characterized in that: The addition amount of the ethyl silicate is 30%-50% of the mass of the nano hard gypsum.

6. The fast hardening concrete crack repair agent according to claim 1, characterized in that: The heating rate during the calcination process is 5-10℃ / min, and after calcination, the product is naturally cooled to room temperature, then passed through a 300-400 mesh screen and reserved.

7. The fast hardening concrete crack repair agent according to claim 1, characterized in that: The length of the polypropylene fiber is 6-12mm, and the diameter is 20-30μm.

8. The method of producing a fast hardening type concrete crack repair agent according to any one of claims 1 to 7, characterized by, The method includes the following steps: S1, the sulfoaluminate cement, silica fume, metakaolin, bimetallic composite seed crystal, double-shell nano hard gypsum, magnesium oxide and polypropylene fiber are sequentially added to a stirrer, and stirred at 1000-1200rpm for 8-12min to obtain a dry mixture; S2, the water reducing agent and water are added to the dry mixture, the stirring speed is adjusted to 600-800rpm, and stirred for 3-5min to obtain a fast-hardening type concrete crack repair agent.

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