A self-healing concrete and its preparation method and application

Abstract

The present invention relates to the technical field of self - repairing concrete, and specifically relates to a self - repairing concrete and its preparation method and application. The self - repairing concrete comprises the following raw materials: cement, coarse aggregate, fine aggregate, modified self - repairing microcapsules, carbon fiber, water - reducing agent, and water; the modified self - repairing microcapsules are obtained by modifying self - repairing microcapsules through argon plasma treatment; the self - repairing microcapsules are composed of a core and a wall; the wall is ethyl cellulose; the core comprises the following raw materials in parts by weight: 30 - 40 parts of silica powder, 20 - 30 parts of sodium silicate, 9 - 15 parts of limestone powder, 2.5 - 5 parts of nano - silica, 20 - 30 parts of basalt powder, 1 - 2 parts of microcrystalline cellulose, 1 - 2 parts of methyl cellulose, and 2 - 3.5 parts of Tween 80; the self - repairing concrete of the present invention has high strength, excellent self - repairing performance, stable repair effect, and good application effect.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly relates to a self - repairing concrete, a preparation method thereof, and an application thereof. Background Art

[0002] Concrete is one of the most widely used and largest - consumed building materials in the world today due to its high compressive strength, good durability, and low cost. It is widely used in the field of modern civil engineering. With the continuous progress of modern materials science, concrete is gradually developing towards high strength, high performance, multi - function, and intelligentization.

[0003] However, cracks will inevitably occur in the process of using concrete. Concrete cracks include structural cracks and non - structural cracks, and the causes of cracks are also different. Structural cracks are caused by external loads, and non - structural cracks are generated due to self - stress. There are many internal factors that cause non - structural cracks, such as plastic deformation, temperature deformation, drying shrinkage, reaction expansion, etc. Once cracks occur in concrete, it will cause a decline in structural performance at least, and lead to serious safety accidents at worst. Therefore, effective measures need to be taken in time to repair the cracks after they occur in concrete. However, the traditional manual crack - repair methods cannot repair internal damage.

[0004] Self - repairing concrete, also known as self - healing concrete, is a new type of intelligent composite material that imitates the regeneration and recovery mechanism of animal bones after injury. By compounding special components (such as carriers carrying repair agents) in traditional concrete components, an intelligent bionic self - healing neural network system is formed inside the concrete, thus endowing it with self - diagnosis and self - repair functions. Self - repairing concrete can actively and automatically repair damaged parts, restore or even improve the performance of concrete materials, which is also the development trend of intelligent concrete.

[0005] A domestic patent with the application number 202110400525.4 discloses a microbial microcapsule for self - repairing concrete cracks, a preparation method thereof, and self - repairing concrete. The microcapsule consists of a core and a wall. The core includes diatomaceous earth, nutrients, Bacillus bacterium liquid, hydroxypropyl methylcellulose, and Tween 80; the wall is ethyl cellulose. The microcapsule has stable performance and good crack self - repair effect; at the same time, the preparation process is simple, without the assistance of mechanical equipment, and only simple grinding and sieving are required to prepare the required microcapsule, with low cost and easy operation. However, the microorganisms in the microcapsule may be inhibited in activity under the influence of the alkalinity environment of concrete, as well as temperature, humidity, light, etc., thus affecting its self - repair effect. Therefore, it is very necessary to develop a self - repairing concrete with stable and excellent self - repair effect. Summary of the Invention

[0006] The object of the present invention is to provide a self - repairing concrete, its preparation method and application. The self - repairing concrete has high strength, excellent self - repairing performance, stable repair effect, easily available raw materials and good application effect.

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] A self - repairing concrete, comprising the following raw materials: cement, coarse aggregate, fine aggregate, modified self - repairing microcapsules, carbon fiber, water - reducing agent, water;

[0009] The modified self - repairing microcapsules are obtained by modifying self - repairing microcapsules through argon plasma treatment; the self - repairing microcapsules are composed of a core and a wall;

[0010] The wall is ethyl cellulose; the core comprises the following raw materials in parts by weight: 30 - 40 parts of silica powder, 20 - 30 parts of sodium silicate, 9 - 15 parts of limestone powder, 2.5 - 5 parts of nano - silica, 20 - 30 parts of basalt powder, 1 - 2 parts of microcrystalline cellulose, 1 - 2 parts of methyl cellulose, 2 - 3.5 parts of Tween 80.

[0011] Preferably, the mass ratio of the core to the wall is 1:0.7 - 1, the particle size of the core is 1 - 2 mm; the particle size of the silica powder is 1 - 5 μm; the particle size of the sodium silicate is below 30 μm; the particle size of the limestone powder is 1 - 15 μm; the particle size of the nano - silica is 30 - 70 nm; the particle size of the basalt powder is 1 - 15 μm.

[0012] Preferably, the preparation method of the modified self - repairing microcapsules comprises the following steps: subjecting the self - repairing microcapsules to argon plasma treatment, with a treatment power of 200 - 300 W and a treatment time of 1.5 - 2.5 min.

[0013] Preferably, the preparation method of the self - repairing microcapsules comprises the following steps:

[0014] S1: Add silica powder, sodium silicate, limestone powder, nano - silica, basalt powder, microcrystalline cellulose, and methyl cellulose to a stirrer, stir and mix evenly to obtain a mixture; add Tween 80 to 28 - 33% of the water by mass of the mixture, and then add it to the mixture and stir into a mass to obtain the wet core material;

[0015] S2: Subject the wet core material to drying, grinding, and sieving in sequence to obtain core particles;

[0016] S3: Dissolve ethyl cellulose powder in an organic solvent to obtain a coating solution; the organic solvent is prepared by mixing xylene and ethanol in a volume ratio of 10:2 - 3; the mass ratio of the ethyl cellulose powder to the organic solvent is 1:9 - 11;

[0017] S4: Place the core particles into a drum. Rotate the drum and spray the coating liquid onto the core particles through a spray gun. After spraying, dry while rolling the drum to obtain the self-healing microcapsules.

[0018] Preferably, the self-healing concrete comprises the following raw materials in parts by weight: 100 parts of cement, 200 - 230 parts of coarse aggregate, 180 - 200 parts of fine aggregate, 2 - 2.7 parts of modified self-healing microcapsules, 2.2 - 3.5 parts of carbon fiber, 0.2 - 0.35 parts of water reducing agent, and 30 - 33 parts of water.

[0019] Preferably, the cement is Portland cement; the fine aggregate is river sand with a fineness modulus of 2.6 - 2.8; the coarse aggregate is crushed stone with a particle size of 5 - 20 mm; the water reducing agent is polycarboxylate water reducing agent.

[0020] Preferably, the carbon fiber is chopped carbon fiber or titanium dioxide modified chopped carbon fiber; the length of the chopped carbon fiber is 4 - 6 mm.

[0021] The preparation method of the titanium dioxide modified chopped carbon fiber comprises the following steps:

[0022] Place the chopped carbon fiber with a length of 4 - 6 mm into titanium dioxide sol, let it stand for 30 - 50 min. After taking it out, place it at room temperature for 12 - 24 h, first vacuum dry at 70 - 80 °C for 2 - 3 h, after grinding and dispersing, then under an argon atmosphere, first heat up to 200 - 250 °C and keep it warm for 1 - 1.5 h, then heat up to 400 - 420 °C and calcine for 2 - 3 h, cool to room temperature, and after grinding and dispersing, obtain the titanium dioxide modified chopped carbon fiber.

[0023] Preferably, the preparation method of the titanium dioxide sol comprises the following steps:

[0024] Add tetrabutyl titanate to absolute ethanol, stir and mix to obtain mixture A; add glacial acetic acid to water, stir and mix to obtain mixture B; then while stirring mixture A, slowly drip mixture B. After dripping, continue to stir for 2.5 - 3 h to obtain titanium dioxide sol.

[0025] The volume ratio of tetrabutyl titanate, glacial acetic acid, absolute ethanol, and water is 10:5 - 5.5:45 - 50:5 - 7.5.

[0026] As a general inventive concept, the present invention provides a preparation method of self-healing concrete, comprising the following steps:

[0027] Weigh each raw material according to the ratio; mix the fine aggregate and carbon fiber evenly to obtain a mixture; then add the mixture to the cement, stir evenly, add water and stir for 100 - 120 s, then add a water reducing agent, stir for 100 - 120 s, and then add coarse aggregate and modified self - healing microcapsules and stir for 100 - 130 s to obtain the product.

[0028] As a general inventive concept, the present invention also provides the application of the above - mentioned self - healing concrete or the self - healing concrete prepared by the above - mentioned preparation method in building houses, roads or bridges.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. In the self - healing concrete of the present invention, the self - healing microcapsules contain a healing agent mainly composed of silica fume, sodium silicate, limestone powder, nano - silica and basalt powder. When cracks occur in the concrete, the capsule wall ruptures, and the silica fume that enters the cracks reacts with the cement hydration products in the concrete environment to form a gel, filling the cracks and repairing them; the added sodium silicate reacts to form calcium silicate to fill the cracks. On this basis, the limestone powder can fill the fine pores generated during the concrete repair process, enhance the density and strength of the concrete, and also promote the hydration reaction of other components, thereby promoting the self - repair of the concrete. In addition, nano - silica can promote the transformation of hydrated calcium silicate colloid into tobermorite - like, making the strength higher and filling the tiny pores inside the concrete to improve the density. After the basalt powder is filled into the cracks, as the main framework material of the repair material, it can form a stable gel with the cement hydration products to self - repair the cracks, and has high strength and durability.

[0031] The self - healing agent composed of silica fume, sodium silicate, limestone powder, nano - silica and basalt powder in the present invention has strong stability in the concrete environment after being encapsulated by the capsule wall, and is less affected by temperature, humidity, light, etc. When repairing concrete cracks, it can achieve excellent repair effects, and the overall raw materials are easy to obtain.

[0032] 2. By performing plasma treatment modification on the surface of the self - healing microcapsules in the present invention, the surface roughness of the self - healing microcapsules can be improved, thereby effectively strengthening the bonding strength between the capsule wall and the concrete. When cracks occur, the self - healing microcapsules are prone to rupture and release the healing agent to repair the concrete, avoiding the generation of cracks between the capsule wall and the concrete.

[0033] 3. The present invention uses carbon fiber to reinforce concrete, which can improve the compressive strength of concrete, increase the toughness of concrete, and effectively enhance the crack resistance of concrete, reducing the width, length, etc. of the initial cracks in concrete. In particular, the titanium dioxide modified short carbon fibers of the present invention have a rough titanium dioxide protrusion structure on the surface compared with ordinary carbon fibers, which can make the carbon fibers more firmly embedded in concrete, effectively preventing the expansion of micro-cracks and the formation of macro-cracks inside the concrete, so that the concrete has better crack resistance, providing better repair conditions for the repair process of self-healing microcapsules to concrete. And it can further improve the tensile, flexural and other properties of concrete.

[0034] 4. The self-healing concrete of the present invention has high strength, excellent self-healing performance and stable repair effect, and has good application effects in the fields of housing construction, roads or bridges, etc. Specific embodiments

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the scope of protection of the present invention.

[0036] Preparation Example 1: Preparation of modified self-healing microcapsules

[0037] A kind of modified self-healing microcapsule is obtained by modifying self-healing microcapsules through argon plasma treatment; the self-healing microcapsule is composed of a core and a wall. The mass ratio of the core to the wall is 1:1.

[0038] The wall is ethyl cellulose; the core includes the following raw materials in parts by weight: 30 parts of silicon micro-powder, 30 parts of sodium silicate, 12 parts of limestone powder, 5 parts of nano-silica, 25 parts of basalt powder, 1.5 parts of microcrystalline cellulose, 1 part of methyl cellulose, and 3 parts of Tween 80.

[0039] The particle size of the silicon micro-powder is 1-5 μm; the particle size of the sodium silicate is below 30 μm; the particle size of the limestone powder is 1-15 μm; the particle size of the nano-silica is 30-70 nm; the particle size of the basalt powder is 1-15 μm.

[0040] The preparation method of the modified self-healing microcapsule specifically includes the following steps:

[0041] S1: Add silica powder, sodium silicate, limestone powder, nano-silica, basalt powder, microcrystalline cellulose, and methyl cellulose into a stirrer, stir and mix evenly to obtain a mixed material; add Tween 80 to 33% of the mass of the mixed material in water, and then add it to the mixed material and stir into a mass to obtain the wet core material;

[0042] S2: Dry, grind, and sieve the wet core material in sequence to obtain core particles with a particle size between 1 - 2 mm;

[0043] S3: Dissolve ethyl cellulose powder in an organic solvent to obtain a coating solution; the organic solvent is prepared by mixing xylene and ethanol in a volume ratio of 10:3; the mass ratio of ethyl cellulose powder to the organic solvent is 1:9;

[0044] S4: Place the core particles in a drum, rotate the drum and spray the coating solution onto the core particles through a spray gun; after spraying, dry while rolling the drum to prepare the self-healing microcapsules;

[0045] S5: Perform argon plasma treatment on the self-healing microcapsules, with a treatment power of 300 W and a treatment time of 2 min.

[0046] Preparation Example 2: Preparation of Modified Self-Healing Microcapsules

[0047] A kind of modified self-healing microcapsule is obtained by modifying the self-healing microcapsule through argon plasma treatment; the self-healing microcapsule consists of a core and a capsule wall. The mass ratio of the core to the capsule wall is 1:0.7,

[0048] The capsule wall is ethyl cellulose; the core includes the following raw materials in parts by weight: 40 parts of silica powder, 25 parts of sodium silicate, 9 parts of limestone powder, 2.5 parts of nano-silica, 30 parts of basalt powder, 2 parts of microcrystalline cellulose, 1.5 parts of methyl cellulose, and 2 parts of Tween 80.

[0049] The particle size of the silica powder is 1 - 5 μm; the particle size of the sodium silicate is below 30 μm; the particle size of the limestone powder is 1 - 15 μm; the particle size of the nano-silica is 30 - 70 nm; the particle size of the basalt powder is 1 - 15 μm.

[0050] The preparation method of the modified self-healing microcapsules specifically includes the following steps:

[0051] S1: Add silica powder, sodium silicate, limestone powder, nano-silica, basalt powder, microcrystalline cellulose, and methyl cellulose into a stirrer, stir and mix evenly to obtain a mixed material; add Tween 80 to 28% of the mass of the mixed material in water, and then add it to the mixed material and stir into a mass to obtain the wet core material;

[0052] S2: Sequentially dry, grind, and screen the core wet material to obtain core particles with a particle size between 1 - 2 mm;

[0053] S3: Dissolve ethyl cellulose powder in an organic solvent to obtain a coating solution; the organic solvent is prepared by mixing xylene and ethanol in a volume ratio of 10:2; the mass ratio of ethyl cellulose powder to the organic solvent is 1:10;

[0054] S4: Place the core particles in a drum, rotate the drum, and spray the coating solution onto the core particles through a spray gun; after spraying, dry while rolling the drum to prepare the self - healing microcapsules;

[0055] S5: Perform argon plasma treatment on the self - healing microcapsules, with a treatment power of 200 W and a treatment time of 1.5 min.

[0056] Preparation Example 3: Preparation of Modified Self - Healing Microcapsules

[0057] A kind of modified self - healing microcapsule is obtained by modifying the self - healing microcapsule through argon plasma treatment; the self - healing microcapsule is composed of a core and a shell. The mass ratio of the core to the shell is 1:0.8.

[0058] The shell is ethyl cellulose; the core includes the following raw materials in parts by weight: 35 parts of silicon micropowder, 20 parts of sodium silicate, 15 parts of limestone powder, 3.5 parts of nano - silica, 30 parts of basalt powder, 1 part of microcrystalline cellulose, 2 parts of methyl cellulose, and 3.5 parts of Tween 80.

[0059] The particle size of the silicon micropowder is 1 - 5 μm; the particle size of the sodium silicate is below 30 μm; the particle size of the limestone powder is 1 - 15 μm; the particle size of the nano - silica is 30 - 70 nm; the particle size of the basalt powder is 1 - 15 μm.

[0060] The preparation method of the modified self - healing microcapsules specifically includes the following steps:

[0061] S1: Add silicon micropowder, sodium silicate, limestone powder, nano - silica, basalt powder, microcrystalline cellulose, and methyl cellulose to a stirrer, stir and mix evenly to obtain a mixed material; add Tween 80 to 30% of the mass of the mixed material in water, and then add it to the mixed material and stir into a mass to obtain the core wet material;

[0062] S2: Sequentially dry, grind, and screen the core wet material to obtain core particles with a particle size between 1 - 2 mm;

[0063] S3: Dissolve ethyl cellulose powder in an organic solvent to obtain a coating solution; the organic solvent is prepared by mixing xylene and ethanol in a volume ratio of 10:3; the mass ratio of ethyl cellulose powder to the organic solvent is 1:11;

[0064] S4: Place the core particles into a drum. Rotate the drum and spray the coating liquid onto the core particles through a spray gun. After spraying, dry while rolling the drum to obtain the self-healing microcapsules.

[0065] S5: Perform argon plasma treatment on the self-healing microcapsules at a treatment power of 300 W for 2.5 min.

[0066] Preparation Example 4: Preparation of Titanium Dioxide-Modified Short Carbon Fibers

[0067] A method for preparing titanium dioxide-modified short carbon fibers includes the following steps:

[0068] Place short carbon fibers with a length of 4 - 6 mm into titanium dioxide sol, let it stand for 50 min. After taking out, place it at room temperature for 24 h, first vacuum dry at 75 °C for 3 h, after grinding and dispersing, then in an argon atmosphere, first heat up to 200 °C and keep it warm for 1.5 h, then heat up to 400 °C and calcine for 3 h, cool to room temperature, and after grinding and dispersing, obtain titanium dioxide-modified short carbon fibers.

[0069] The preparation method of the above titanium dioxide sol includes the following steps:

[0070] Add tetrabutyl titanate to absolute ethanol, stir and mix to obtain mixture A; add glacial acetic acid to water, stir and mix to obtain mixture B; then slowly drip mixture B while stirring mixture A. After dripping, continue to stir for 3 h to obtain titanium dioxide sol; the volume ratio of tetrabutyl titanate, glacial acetic acid, absolute ethanol, and water is 10:5:45:6.5.

[0071] Preparation Example 5: Preparation of Titanium Dioxide-Modified Short Carbon Fibers

[0072] A method for preparing titanium dioxide-modified short carbon fibers includes the following steps:

[0073] Place short carbon fibers with a length of 4 - 6 mm into titanium dioxide sol, let it stand for 40 min. After taking out, place it at room temperature for 12 h, first vacuum dry at 80 °C for 2 h, after grinding and dispersing, then in an argon atmosphere, first heat up to 250 °C and keep it warm for 1.5 h, then heat up to 400 °C and calcine for 3 h, cool to room temperature, and after grinding and dispersing, obtain titanium dioxide-modified short carbon fibers.

[0074] The preparation method of the above titanium dioxide sol includes the following steps:

[0075] Tetrabutyl titanate was added to absolute ethanol, and after stirring and mixing, a mixed solution A was obtained; glacial acetic acid was added to water, and after stirring and mixing, a mixed solution B was obtained; then, while stirring mixed solution A, mixed solution B was slowly added dropwise. After the addition was completed, stirring was continued for 2.5 h to obtain a titanium dioxide sol; the volume ratio of tetrabutyl titanate, glacial acetic acid, absolute ethanol, and water was 10:5:45:5.

[0076] Preparation Example 6: Preparation of Titanium Dioxide-Modified Short Carbon Fibers

[0077] A method for preparing titanium dioxide-modified short carbon fibers includes the following steps:

[0078] Short carbon fibers with a length of 4-6 mm were placed in the titanium dioxide sol, allowed to stand for 30 min, taken out, and left at room temperature for 18 h. Then, they were first vacuum dried at 70 °C for 2.5 h, ground and dispersed, and then, in an argon atmosphere, first heated to 220 °C and held for 1 h, then heated to 420 °C and calcined for 2 h, cooled to room temperature, ground and dispersed to obtain titanium dioxide-modified short carbon fibers.

[0079] The preparation method of the above-mentioned titanium dioxide sol includes the following steps:

[0080] Tetrabutyl titanate was added to absolute ethanol, and after stirring and mixing, a mixed solution A was obtained; glacial acetic acid was added to water, and after stirring and mixing, a mixed solution B was obtained; then, while stirring mixed solution A, mixed solution B was slowly added dropwise. After the addition was completed, stirring was continued for 3 h to obtain a titanium dioxide sol; the volume ratio of tetrabutyl titanate, glacial acetic acid, absolute ethanol, and water was 10:5.5:50:7.5.

[0081] Example 1:

[0082] A self-healing concrete includes the following raw materials in parts by weight: 100 parts of P.O 42.5 ordinary Portland cement, 220 parts of coarse aggregate, 200 parts of fine aggregate, 2.5 parts of modified self-healing microcapsules, 2.5 parts of short carbon fibers, 0.25 part of polycarboxylate water reducer, and 32 parts of water.

[0083] The fine aggregate is river sand with a fineness modulus of 2.6; the coarse aggregate is crushed stone with a particle size of 5-20 mm; the modified self-healing microcapsules are prepared by the method in Preparation Example 2; the length of the short carbon fibers is 4-6 mm.

[0084] The preparation method of the self-healing concrete in this example includes the following steps:

[0085] Weigh each raw material according to the ratio; mix the fine aggregate and carbon fibers evenly to obtain a mixture; then add the mixture to the cement, stir evenly, add water and stir for 120 s, then add the water reducer, stir for 100 s, and then add the coarse aggregate and modified self-healing microcapsules and stir for 120 s to obtain the product.

[0086] Example 2:

[0087] A self-healing concrete, comprising the following raw materials in parts by weight: 100 parts of P.O 42.5 ordinary portland cement, 200 parts of coarse aggregate, 180 parts of fine aggregate, 2.7 parts of modified self-healing microcapsules, 2.2 parts of short carbon fibers, 0.25 part of polycarboxylate water reducer, and 30 parts of water.

[0088] The fine aggregate is river sand with a fineness modulus of 2.6; the coarse aggregate is crushed stone with a particle size of 5-20 mm; the modified self-healing microcapsules are prepared by the method in Preparation Example 1; the length of the short carbon fibers is 4-6 mm.

[0089] The preparation method of the self-healing concrete in this example comprises the following steps:

[0090] Weigh each raw material according to the ratio; mix the fine aggregate and carbon fibers evenly to obtain a mixture; then add the mixture to the cement, stir evenly, add water and stir for 120 s, then add the water reducer, stir for 110 s, and then add the coarse aggregate and modified self-healing microcapsules and stir for 130 s to obtain the product.

[0091] Example 3:

[0092] A self-healing concrete, comprising the following raw materials in parts by weight: 100 parts of P.O 42.5 ordinary portland cement, 230 parts of coarse aggregate, 200 parts of fine aggregate, 2.4 parts of modified self-healing microcapsules, 3 parts of short carbon fibers, 0.2 part of polycarboxylate water reducer, and 30 parts of water.

[0093] The fine aggregate is river sand with a fineness modulus of 2.8; the coarse aggregate is crushed stone with a particle size of 5-20 mm; the modified self-healing microcapsules are prepared by the method in Preparation Example 3; the length of the short carbon fibers is 4-6 mm.

[0094] The preparation method of the self-healing concrete in this example comprises the following steps:

[0095] Weigh each raw material according to the ratio; mix the fine aggregate and carbon fibers evenly to obtain a mixture; then add the mixture to the cement, stir evenly, add water and stir for 110 s, then add the water reducer, stir for 120 s, and then add the coarse aggregate and modified self-healing microcapsules and stir for 100 s to obtain the product.

[0096] Example 4:

[0097] A self-healing concrete, comprising the following raw materials in parts by weight: 100 parts of P.O 42.5 ordinary portland cement, 220 parts of coarse aggregate, 195 parts of fine aggregate, 2 parts of modified self-healing microcapsules, 3.5 parts of short carbon fibers, 0.35 part of polycarboxylate water reducer, and 33 parts of water.

[0098] The fine aggregate is river sand with a fineness modulus of 2.7; the coarse aggregate is crushed stone with a particle size of 5 - 20 mm; the modified self - healing microcapsules are prepared by the method in Preparation Example 1; the length of the short - cut carbon fiber is 4 - 6 mm.

[0099] The preparation method of the self - healing concrete in this example includes the following steps:

[0100] Weigh each raw material according to the ratio; mix the fine aggregate and carbon fiber evenly to obtain a mixture; then add the mixture to the cement, stir evenly, add water and stir for 100 s, then add a water - reducing agent and stir for 100 s, and finally add the coarse aggregate and modified self - healing microcapsules and stir for 130 s to obtain the product.

[0101] Example 5:

[0102] A self - healing concrete, different from Example 4, is that the short - cut carbon fiber is replaced by the titanium dioxide - modified short - cut carbon fiber prepared by the method in Preparation Example 6.

[0103] Example 6:

[0104] A self - healing concrete, different from Example 4, is that the short - cut carbon fiber is replaced by the titanium dioxide - modified short - cut carbon fiber prepared by the method in Preparation Example 4.

[0105] Example 7:

[0106] A self - healing concrete, different from Example 4, is that the short - cut carbon fiber is replaced by the titanium dioxide - modified short - cut carbon fiber prepared by the method in Preparation Example 5.

[0107] Comparative Example 1:

[0108] Different from Example 4, the modified self - healing microcapsules are replaced by the self - healing microcapsules prepared in Preparation Example 1.

[0109] Comparative Example 2:

[0110] Different from Example 4, the capsule core includes the following raw materials by weight: 30 parts of silica powder, 30 parts of sodium silicate, 1.5 parts of microcrystalline cellulose, 1 part of methyl cellulose, and 3 parts of Tween 80.

[0111] Performance test:

[0112] The self-healing concrete prepared in Examples 1-7 and Comparative Examples 1-2 was made into test blocks of 100 mm×100 mm×100 mm, and cured under standard conditions for 7 d and 28 d. Then, the compressive strength of the obtained test blocks was tested in accordance with the Standard Test Method for Mechanical Properties of Ordinary Concrete (GB / T50081-2002). The self-healing concrete test blocks after 28 d of curing were cracked by a testing machine to form cracks with a width of 0.1-0.15 mm in the concrete, and then cured for another 28 d and the compressive strength was tested. The specific test results are shown in Table 1.

[0113] Table 1:

[0114] 7d compressive strength / MPa 28d compressive strength / MPa Initial crack width / mm Compressive strength after cracking and curing for 28d / MPa Example 1 36.7 57.8 0.13 55.8 Example 2 35.7 56.0 0.10 55.0 Example 3 37.2 57.5 0.11 56.3 Example 4 37.5 58.3 0.13 56.4 Example 5 40.3 63.3 0.11 62.3 Example 6 40.8 64.2 0.14 62.8 Example 7 40.5 63.6 0.12 62.5 Comparative Example 1 37.2 57.8 0.12 53.2 Comparative Example 2 37.4 58.1 0.12 49.2

[0115] As can be seen from Table 1, the self-healing concrete prepared by the present invention has excellent self-healing performance and high overall strength. By comparing Example 4 with Examples 5-7, it can be seen that the carbon fiber modified with titanium dioxide can enhance the concrete and has higher compressive strength. By comparing Example 1 with Comparative Examples 1-2, it can be seen that the argon plasma treatment modification of the surface of the self-healing microcapsules can improve the self-healing performance of the self-healing concrete, and adding limestone powder, nano-silica and basalt powder to the core of the self-healing microcapsules can significantly improve the self-healing performance of the self-healing concrete.

[0116] The above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A self-repairing concrete, characterized in that: The raw materials include the following parts by weight: 100 parts of cement, 200-230 parts of coarse aggregate, 180-200 parts of fine aggregate, 2-2.7 parts of modified self-repairing microcapsules, 2.2-3.5 parts of carbon fiber, 0.2-0.35 parts of water reducer, and 30-33 parts of water; The modified self-repairing microcapsules are obtained by modifying the self-repairing microcapsules by subjecting them to argon plasma treatment; The preparation method of the modified self-repairing microcapsule comprises the following steps: subjecting the self-repairing microcapsule to argon plasma treatment, with a treatment power of 200-300W and a treatment time of 1.5-2.5min; the self-repairing microcapsule is composed of a capsule core and a capsule wall; The capsule wall is ethyl cellulose; the capsule core comprises the following raw materials in parts by weight: 30-40 parts of silicon micropowder, 20-30 parts of sodium silicate, 9-15 parts of limestone powder, 2.5-5 parts of nano silicon dioxide, 20-30 parts of basalt powder, 1-2 parts of microcrystalline cellulose, 1-2 parts of methyl cellulose, and 2-3.5 parts of Tween 80; The carbon fiber is titanium dioxide modified chopped carbon fiber; the preparation method of the titanium dioxide modified chopped carbon fiber comprises the following steps: Short-cut carbon fibers with a length of 4-6 mm are placed in a titanium dioxide sol, allowed to stand for 30-50 minutes, taken out, and placed at room temperature for 12-24 hours, and then vacuum dried at 70-80°C for 2-3 hours. After grinding and dispersion, the temperature is first raised to 200-250°C in an argon atmosphere and kept for 1-1.5 hours, and then the temperature is raised to 400-420°C for calcination for 2-3 hours, cooled to room temperature, and ground and dispersed to obtain the titanium dioxide modified short-cut carbon fibers.

2. The self-repairing concrete according to claim 1, characterized in that: The mass ratio of the capsule core to the capsule wall is 1:0.7-1, the particle size of the capsule core is 1-2mm; the particle size of the silicon micropowder is 1-5μm; the particle size of the sodium silicate is below 30μm; the particle size of the limestone powder is 1-15μm; the particle size of the nano-silicon dioxide is 30-70nm; and the particle size of the basalt powder is 1-15μm.

3. The self-repairing concrete according to claim 1, characterized in that: The preparation method of the self-repairing microcapsule comprises the following steps: S1: Add silicon powder, sodium silicate, limestone powder, nano silicon dioxide, basalt powder, microcrystalline cellulose and methyl cellulose into a blender, stir and mix evenly to obtain a mixture; add Tween 80 to water with a mass of 28-33% of the mixture, and then add the water to the mixture and stir to obtain a wet material for the capsule core; S2: drying, grinding and sieving the capsule core wet material in sequence to obtain capsule core particles; S3: dissolving ethyl cellulose powder in an organic solvent to obtain a coating solution; the organic solvent is prepared by mixing xylene and ethanol in a volume ratio of 10:2-3; the mass ratio of the ethyl cellulose powder to the organic solvent is 1:9-11; S4: placing the capsule core particles in a drum, rotating the drum and spraying the coating liquid onto the core particles through a spray gun; after spraying, drying while rolling the drum to prepare the self-healing microcapsules.

4. The self-repairing concrete according to claim 1, characterized in that: The cement is silicate cement; the fine aggregate is river sand with a fineness modulus of 2.6-2.8; the coarse aggregate is crushed stone with a particle size of 5-20 mm; and the water reducer is a polycarboxylate water reducer.

5. The self-repairing concrete according to claim 1, characterized in that: The preparation method of the titanium dioxide sol comprises the following steps: Tetrabutyl titanate is added to anhydrous ethanol, and the mixture is stirred to obtain a mixed solution A; glacial acetic acid is added to water, and the mixture is stirred to obtain a mixed solution B; then the mixed solution B is slowly added dropwise while the mixed solution A is stirred, and after the addition is completed, the stirring is continued for 2.5-3 hours to obtain a titanium dioxide sol; The volume ratio of tetrabutyl titanate, glacial acetic acid, anhydrous ethanol and water is 10:5-5.5:45-50:5-7.

5.

6. A method for preparing the self-repairing concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: The fine aggregate and the carbon fiber are mixed evenly to obtain a mixture; then the mixture is added to cement, stirred evenly, water is added and stirred for 100-120s, a water reducer is added and stirred for 100-120s, and then coarse aggregate and modified self-repairing microcapsules are added and stirred for 100-130s to obtain the mixture.

7. Use of the self-repairing concrete according to any one of claims 1 to 5 or the self-repairing concrete prepared by the preparation method according to claim 6 in building construction, roads or bridges.