Mine weathered material self-repairing concrete and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to mine weathered material self-repairing concrete and a preparation method thereof.The mine weathered material self-repairing concrete is prepared from 50-70 parts of weathered coarse aggregate, 20-40 parts of weathered fine aggregate, 5-15 parts of furnace bottom slag, 5-25 parts of sodium silicate microcapsules, 10-20 parts of calcium hydroxide microcapsules, 10-20 parts of cement, 5-15 parts of water and 0.05-0.1 part of water reducing agent; the preparation method comprises the following steps: pretreating the furnace bottom slag, pretreating the mine weathered material, preparing the microcapsule, preparing the self-repairing concrete mixture, and forming and curing. The concrete has a self-repairing function.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a self-repairing concrete made from mine weathered material and a preparation method thereof. Background Art

[0002] When preparing concrete, aggregates and admixtures are indispensable important raw materials. Aggregates usually come from mine exploitation, while admixtures are usually fly ash.

[0003] On the one hand, a large amount of mine weathered material is also generated during the process of mine exploitation. However, due to the characteristics of low strength and large voids of mine weathered material, its loose structure is prone to deformation and damage under stress, and it is difficult to meet the requirements of concrete materials for compressive strength and shear strength. Therefore, it cannot be directly used as an aggregate, which is not only a waste of resources but also brings many potential environmental problems. Referring to the requirements of GB / T 14685-2022 "Pebbles and Crushed Stones for Construction" and JGJ52-2006 "Standard for Quality and Inspection Methods of Sand and Gravel for Ordinary Concrete", through systematic pretreatment and precise mix design of mine weathered material, the weathered material aggregate can only be used for medium and low strength concrete to achieve the dual goals of resource utilization and cost reduction and efficiency improvement.

[0004] On the other hand, fly ash is mainly the fine particle waste collected from the flue gas after coal combustion in coal-fired power plants. However, in addition to fly ash, bottom ash will also be generated at the bottom of the boiler during the coal combustion process. In terms of microscopic morphology, fly ash is often finer and spherical, while the particle shape of bottom ash is usually irregular and the surface is rough. The irregular particle shape will increase the water consumption of concrete and the cohesiveness of the mixture, reduce the workability and fluidity of concrete, and at the same time will also cause the decline of the compressive strength and flexural strength of concrete; in addition, the activity of bottom ash is relatively low, and it cannot effectively react with the hydration products of cement when added to concrete, and it is difficult to play a good strengthening and modification role in building materials. Referring to the requirements of GB / T 30190 (Technical Specification for Bottom Ash Aggregate for Concrete), the concrete added with bottom ash is suitable for non-load-bearing structures, low-strength concrete, road engineering or temporary projects, and needs to be verified by small-scale tests before large-scale application, and the concrete performance needs to be monitored regularly. Summary of the Invention

[0005] Based on the characteristics of mine weathered material and bottom ash, in order to expand the high-value utilization of mine weathered material and bottom ash, the present invention proposes a self-repairing concrete made from mine weathered material and a preparation method thereof.

[0006] A kind of mine weathered material self - repairing concrete of the present invention is characterized in that by weight, the mine weathered material self - repairing concrete comprises the following materials: 50 - 70 parts of weathered coarse aggregate, 20 - 40 parts of weathered fine aggregate, 5 - 15 parts of bottom slag, 5 - 25 parts of sodium silicate microcapsule, 10 - 20 parts of calcium hydroxide microcapsule, 10 - 20 parts of cement, 5 - 15 parts of water and 0.05 - 0.1 part of water - reducing agent.

[0007] The weathered coarse aggregate is processed from mine weathered material. The soundness of the weathered coarse aggregate is 8% - 20%, the crushing index is 20% - 40%, the rock compressive strength ≥ 45MPa, the sulfide and sulfate content ≤ 1%, the apparent density is 2600kg / m3 - 3000kg / m3, the mud powder content ≤ 2%, and the water absorption rate is 1% - 3%.

[0008] The weathered fine aggregate is processed from mine weathered material, with its stone powder content ≤ 15%, methylene blue value ≤ 1.4, soundness of 5% - 20%, crushing index of 20% - 50%, chloride content ≤ 0.06%, sulfide and sulfate content ≤ 0.5%, light substances ≤ 1%, mica content of 0% - 5%, apparent density of 2500kg / m3 - 3000kg / m3, mud lump content ≤ 2%, and saturated surface dry water absorption rate of 0.2% - 3%.

[0009] The SiO2 content of the bottom slag is 45% - 60%, and its particle size ≤ 4.75mm. When the particle size of the bottom slag ≤ 20μm, it is used as a blending material to replace cement; when the particle size of the bottom slag is 20μm - 4.75mm, it is used as a fine aggregate to replace the weathered fine aggregate.

[0010] The core of the sodium silicate microcapsule is sodium silicate with a concentration of 0.8 - 1.2mol / L, the capsule wall is ethyl cellulose, and the dissolving substance of the capsule wall is an aromatic hydrocarbon solvent or an alcohol solvent.

[0011] The core of the calcium hydroxide microcapsule is calcium hydroxide with a concentration of 0.3 - 0.6mol / L, the capsule wall is ethyl cellulose, and the dissolving substance of the capsule wall is an aromatic hydrocarbon solvent or an alcohol solvent.

[0012] The preparation process of a kind of mine weathered material self - repairing concrete comprises the following steps:

[0013] (1) Pretreat the bottom slag: Immerse the bottom slag in a suspension of Bacillus pasteurii, then dry the bottom slag by a low - temperature drying method at ≤ 40°C, and finally classify the bottom slag: Reserve the bottom slag with a particle size ≤ 20μm as a blending material to replace cement, and reserve the bottom slag with a particle size of 20μm - 4.75mm as a fine aggregate to replace the weathered fine aggregate;

[0014] (2) Pretreatment of mine weathered material: First, the mine weathered material is processed into weathered coarse aggregate and weathered fine aggregate through crushing and ball milling. Then, the weathered coarse aggregate and weathered fine aggregate are respectively put into the suspension of Bacillus pasteurii after soaking the bottom slag of the furnace. Finally, the weathered coarse aggregate and weathered fine aggregate are dried for standby by a low-temperature drying method at ≤40°C;

[0015] (3) Preparation of microcapsules: The core material and the dispersant are dispersed into the solvent by ultrasonic waves. Then, the wall material is dissolved in a small amount of solvent, and the dissolved wall material is slowly dropped into the dispersed core material solution, and continuously stirred at a speed of 500 rpm. Then, the catalyst is dissolved in a small amount of solvent, slowly dropped into the above reaction system, and the reaction temperature is controlled at 50°C. The polymerization reaction is carried out under stirring conditions for 2 - 4 h to form microcapsules. Finally, the microcapsules are separated by centrifugal filtration at a speed of 3000 rpm, washed repeatedly with deionized water, and finally freeze-dried to obtain dry sodium silicate microcapsules and calcium oxide microcapsules;

[0016] (4) Preparation of self-healing concrete mixture: According to the actual weight of the bottom slag of the furnace with two types of particle sizes obtained, the weights of the actually selected cement and weathered fine aggregate are increased or decreased according to the ratio. Weigh each material by mass percentage. First, the bottom slag with a particle size ≤20 μm, 50% of the bottom slag with a particle size of 20 μm - 4.75 mm, 50% of the weathered coarse aggregate, 50% of the weathered fine aggregate, cement, sodium silicate microcapsules and calcium hydroxide microcapsules are dry-mixed and stirred at a speed of 25 rpm for 1 min. Then, the remaining 50% of the bottom slag with a particle size of 20 μm - 4.75 mm, 50% of the weathered coarse aggregate and 50% of the weathered fine aggregate are added and continue to be dry-mixed at a speed of 25 rpm for 1 min. Finally, water and water reducer are added and wet-mixed at a speed of 25 rpm for 2 min to obtain the self-healing concrete mixture;

[0017] (5) Molding and curing: The self-healing concrete in the mold is vibrated by a low-frequency vibrator, and the vibration time ≤1 min. The self-healing concrete of the mine weathered material without demolding is cured for 1 d by covering with a film at room temperature of 23 ± 2°C and relative humidity of 65 ± 15%. After the self-healing concrete is cured for 1 d and hardened, it is put into a standard curing room with indoor conditions of 20 ± 2°C and relative humidity ≥95%, and the final self-healing concrete of the mine weathered material is obtained after curing for 28 d.

[0018] Furthermore, the concentration of OD600 in the suspension of Bacillus pasteurii described in step (1) is 0.8 - 1.2, the treatment time is 3 h, the suspension of Bacillus pasteurii is fixed in the pores of the slag by physical adsorption, the soaking temperature is 20 - 30°C, and the pH is 7 - 9.

[0019] Further, in step (2), the OD600 concentration in the Bacillus pasteurii suspension is 0.8 - 1.2, the calcium source concentration is 0.5 - 1 mol / L, the weathered coarse aggregate treatment time is 7 - 10 d, and the soaking temperature is 20 - 30°C; the weathered fine aggregate is treated by soaking in the Bacillus pasteurii suspension, the OD600 concentration in the Bacillus pasteurii suspension is 0.8 - 1.2, the calcium source concentration is 0.5 - 1 mol / L, the treatment time is 4 - 7 d, the soaking temperature is 20 - 30°C, and the pH is 7 - 9.

[0020] Furthermore, yeast extract is added to the Bacillus pasteurii suspension described in step (2), and the yeast extract includes one or any combination of amino acids, peptides, vitamins, nucleotides, carbohydrates, and minerals.

[0021] The present invention has the following advantages:

[0022] 1) The self - healing concrete mechanism of the present invention lies in that the mechanism of Bacillus pasteurii producing CO2 is to catalyze the hydrolysis of urea by secreting urease to generate carbon dioxide. After the carbon dioxide dissolves in water, it reacts with calcium ions to form carbonate. The bottom slag of the furnace is treated by soaking in Bacillus pasteurii suspension. The bottom slag of the furnace has a porous structure and serves as a solid - loading material for Bacillus pasteurii. The larger the particle size of the bottom slag of the furnace, the more microorganisms it can solid - load, and the relatively more calcium carbonate precipitate it can generate; the magnesium ions contained in the mine weathered material, as co - factors of urease, can enhance the activity of urease, stabilize the structure of urease, and participate in the catalytic reaction, thus accelerating the generation efficiency of carbonate ions; the porous structure of the bottom slag of the furnace also provides a good solid - loading environment for Bacillus pasteurii and trace metal ions. The bottom slag of the furnace used as cement is used to repair the fine cracks in the concrete, while the bottom slag of the furnace used as weathered fine aggregate is used to repair the coarser cracks in the concrete.

[0023] 2) The bottom slag of the furnace is rich in calcium elements, so a small amount of calcium carbonate is generated by the calcium ions and carbonate ions dissolved in the Bacillus pasteurii suspension; the Bacillus pasteurii suspension soaked with the bottom slag of the furnace is rich in calcium source when reused. On the one hand, the dosage of the Bacillus pasteurii suspension is saved, and on the other hand, there is no need to add the traditional calcium source CaCl to the Bacillus pasteurii suspension additionally. The mine weathered material is rich in carbonate, so a large amount of calcium carbonate can be generated in the reaction, and the efficiency of crack self - healing is significantly improved; in addition, the clay minerals contained in the mine weathered material have adsorption and slow - release effects, which is beneficial to prolong the activity of Bacillus pasteurii and further improve the durability of crack self - healing.

[0024] 3) The combined use of mine weathered materials and furnace bottom slag has multiple synergistic effects: First, mine weathered materials usually contain components such as silicon and aluminum, while furnace bottom slag is rich in elements such as calcium and iron. After the two are combined, substances such as calcium silicate hydrate and calcium aluminate hydrate may be generated through chemical reactions to enhance the mechanical properties of self-healing concrete; Second, components such as clay minerals and iron oxides in mine weathered materials and furnace bottom slag have the ability to adsorb and solidify heavy metals, which is used to reduce the environmental risk of the materials; Third, the combination of the two materials forms a porous or layered structure, improving the permeability, crack resistance and durability of the materials; Fourth, the micropores of the furnace bottom slag can adsorb the fine powder of the mine weathered materials, forming a micro-filling effect, reducing the porosity inside the concrete and improving the density.

[0025] 4) The furnace bottom slag, sodium silicate microcapsules and calcium hydroxide microcapsules can play a synergistic role in repairing microcracks in concrete: When cracks appear in the concrete, the sodium silicate microcapsules and calcium hydroxide microcapsules rupture, releasing the components in the capsules. The released sodium silicate and calcium hydroxide will undergo a chemical reaction to generate calcium silicate gel to fill the cracks;

[0026] In addition, the released sodium silicate can be used as an alkaline activator to further improve the pozzolanic activity of the furnace bottom slag. The furnace bottom slag with higher pozzolanic activity will then react chemically with the released calcium hydroxide to generate calcium silicate hydrate to fill the cracks. Specific implementation methods

[0027] Example 1: A mine weathered material self-healing concrete, by weight, 9 parts of furnace bottom slag are selected. After measurement, the content of furnace bottom slag with a particle size ≤ 20μm is about 73%, and the content of furnace bottom slag with a particle size of 20μm - 4.75mm is about 26%. Since the content of furnace bottom slag with a particle size ≥ 4.75mm is low and has little impact on the overall quality, it is not classified separately.

[0028] The planned amount of cement is 20 parts, and the planned amount of weathered fine aggregate is 34 parts. Due to the addition of an appropriate amount of furnace bottom slag, the actual amount of cement used is 15 parts, and the actual amount of weathered fine aggregate used is 30 parts

[0029] In addition, 60 parts of weathered coarse aggregate, 15 parts of sodium silicate microcapsules, 15 parts of calcium hydroxide microcapsules, 8 parts of water and 0.07 parts of water reducer are selected.

[0030] The preparation process of the mine weathered material self-healing concrete is as follows:

[0031] The bottom slag is soaked in the suspension of Bacillus pasteurii. The OD600 concentration in the suspension of Bacillus pasteurii is 0.8 - 1.2, the treatment time is 3 h, the soaking temperature is 22 °C, and the pH is 7. Then, the bottom slag is dried by a low-temperature drying method at ≤40 °C. The bottom slag is classified for treatment: the bottom slag with a particle size ≤20 μm is used as an admixture to replace cement for standby, and the bottom slag with a particle size of 20 μm - 4.75 mm is used as fine aggregate to replace weathered fine aggregate for standby. After measurement, after the bottom slag is soaked in the suspension of Bacillus pasteurii, the provided calcium source concentration is 0.5 - 1 mol / L, providing a sufficient calcium source basis for the self-healing of concrete.

[0032] The suspension of Bacillus pasteurii after soaking the bottom slag is reused. The weathered coarse aggregate and weathered fine aggregate are respectively put into the above-mentioned suspension of Bacillus pasteurii for soaking treatment. The treatment time of the weathered coarse aggregate is 8 d, the soaking temperature is 25 °C, the treatment time of the weathered fine aggregate is 6 d, the soaking temperature is 26 °C, and finally, the weathered coarse aggregate and weathered fine aggregate are dried by a low-temperature drying method at ≤40 °C for standby;

[0033] The core material and the dispersant are dispersed into the solvent by ultrasonic waves. Then, the wall material is dissolved in a small amount of solvent, and the dissolved wall material is slowly dropped into the dispersed core material solution, and continuously stirred at a speed of 500 rpm. Then, the catalyst is dissolved in a small amount of solvent, slowly dropped into the above reaction system, and the reaction temperature is controlled at 50 °C. The polymerization reaction is carried out under stirring conditions, and the reaction time is 2 - 4 h to form microcapsules. Finally, the microcapsules are centrifugally filtered and separated at a speed of 3000 rpm, washed repeatedly with deionized water, and finally freeze-dried to obtain dry sodium silicate microcapsules and calcium oxide microcapsules;

[0034] The bottom slag with a particle size ≤20 μm, 50% of the bottom slag with a particle size of 20 μm - 4.75 mm, 50% of the weathered coarse aggregate, 50% of the weathered fine aggregate, cement, sodium silicate microcapsules, and calcium hydroxide microcapsules are dry-mixed and stirred at a speed of 25 rpm for 1 min. Then, the remaining 50% of the bottom slag with a particle size of 20 μm - 4.75 mm, 50% of the weathered coarse aggregate, and 50% of the weathered fine aggregate are added and continuously dry-mixed at a speed of 25 rpm for 1 min. Finally, water and water reducer are added and wet-mixed at a speed of 25 rpm for 2 min to obtain a self-healing concrete mixture;

[0035] A low-frequency vibrator is used to vibrate the self-healing concrete in the mold. The vibration time ≤1 min. The self-healing concrete of the mine weathered material that has not been demolded is cured by covering with a film at room temperature of 23 ± 2 °C and relative humidity of 65 ± 15% for 1 d. After the self-healing concrete is cured for 1 d and hardened, it is put into a standard curing room with indoor conditions of 20 ± 2 °C and relative humidity ≥95%. After curing for 28 d, the final self-healing concrete of the mine weathered material is obtained.

[0036] In all the following examples and control examples, the preparation methods of the bottom slag and the weathered mine aggregate self-healing concrete are the same as those in Example 1.

[0037] Example 2: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 5 parts of bottom slag, 15 parts of sodium silicate microcapsules, 15 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0038] Example 3: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 15 parts of bottom slag, 15 parts of sodium silicate microcapsules, 15 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0039] Example 4: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 9 parts of bottom slag, 5 parts of sodium silicate microcapsules, 15 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0040] Example 5: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 9 parts of bottom slag, 25 parts of sodium silicate microcapsules, 15 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0041] Example 6: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 9 parts of bottom slag, 15 parts of sodium silicate microcapsules, 10 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0042] Example 7: Example 6: The weathered mine aggregate self-healing concrete comprises the following materials: 60 parts of weathered coarse aggregate, 30 parts of weathered fine aggregate, 9 parts of bottom slag, 15 parts of sodium silicate microcapsules, 20 parts of calcium hydroxide microcapsules, 15 parts of cement, 8 parts of water and 0.07 parts of water reducer.

[0043] Crack repair situation test: After the end of the concrete curing period, the initial compressive strength of the concrete was tested by applying a load through experiments, and then cracks were generated in the concrete through pre-loss treatment (pre-compression treatment for 3 minutes with a force of 50% of the initial compressive strength), and then the repair situation of the cracks was observed. The specific test results are as follows.

[0044]

[0045] The compressive strength and the compressive strength after repair of Example 1 are significantly better than those of other examples. The recycled concrete has a high density and is the optimal choice of the present invention.

[0046] Control group 1: Compared with Example 1, the bottom slag was not pretreated with the suspension of Bacillus pasteurii, and other conditions were the same.

[0047] Control group 2: Compared with Example 1, the weathered mine material was not pretreated with the suspension of Bacillus pasteurii, and other conditions were the same.

[0048] Control group 3: Compared with Example 1, the weathered mine material was pretreated with the suspension of Bacillus pasteurii that had not been soaked in the bottom slag (that is, no calcium source was added to the suspension of Bacillus pasteurii), and other conditions were the same.

[0049] According to the standards "Sand for construction" and "Pebbles and crushed stones for construction", the following table shows the changes in the crushing index of Example 1 and Control groups 1 - 3.

[0050] Group number Initial crushing index / % 3d crushing index / % 6d crushing index / % 9d crushing index / % Example 1 45 44 44 43 Control group 1 43 40 32 25 Control group 2 43 42 35 27 Control group 3 43 42 37 32

[0051] The method of first soaking the bottom slag and then soaking the weathered mine material in Example 1 makes the self - repairing concrete have good repair durability and high self - repair efficiency.

Claims

1. A self-healing concrete for mine weathered materials, characterized in that By weight, the self-healing concrete made from weathered mine materials comprises the following materials: 50 - 70 parts of weathered coarse aggregate, 20 - 40 parts of weathered fine aggregate, 5 - 15 parts of bottom slag, 5 - 25 parts of sodium silicate microcapsules, 10 - 20 parts of calcium hydroxide microcapsules, 10 - 20 parts of cement, 5 - 15 parts of water, and 0.05 - 0.1 part of water reducing agent.

2. The self-repairing concrete for mine weathered materials according to claim 1, characterized in that The weathered coarse aggregate is processed from weathered mine materials. The soundness of the weathered coarse aggregate is 8% - 20%, the crushing index is 20% - 40%, the rock compressive strength ≥ 45 MPa, the sulfide and sulfate content ≤ 1%, the apparent density is 2600 kg / m3 - 3000 kg / m3, the mud powder content ≤ 2%, and the water absorption rate is 1% - 3%.

3. The self-repairing concrete for mine weathered materials as described in claim 1, characterized in that The weathered fine aggregate is processed from weathered mine materials. Its stone powder content ≤ 15%, methylene blue value ≤ 1.4, soundness is 5% - 20%, crushing index is 20% - 50%, chloride content ≤ 0.06%, sulfide and sulfate content ≤ 0.5%, light substances ≤ 1%, mica content is 0% - 5%, apparent density is 2500 kg / m3 - 3000 kg / m3, mud lump content ≤ 2%, and saturated surface dry water absorption rate is 0.2% - 3%.

4. The self-healing concrete for mine weathered materials according to claim 1, characterized in that The SiO2 content of the bottom slag is 45% - 60%, and its particle size ≤ 4.75 mm.

5. The self-repairing concrete for mine weathered material according to claim 1, wherein The core of the sodium silicate microcapsule is sodium silicate with a concentration of 0.8 - 1.2 mol / L, the capsule wall is ethyl cellulose, and the dissolving substance of the capsule wall is aromatic hydrocarbon solvent or alcohol solvent.

6. The self-repairing concrete made of weathered mine materials according to claim 1, characterized in that The core of the calcium hydroxide microcapsule is calcium hydroxide with a concentration of 0.3 - 0.6 mol / L, the capsule wall is ethyl cellulose, and the dissolving substance of the capsule wall is aromatic hydrocarbon solvent or alcohol solvent.

7. A preparation method of self-repairing concrete for mine weathered materials, characterized in that It includes the following steps: Pretreatment of bottom slag: Immerse the bottom slag in a suspension of Bacillus pasteurii, then dry the bottom slag by low-temperature drying method at ≤ 40 °C, and finally classify the bottom slag: Reserve the bottom slag with a particle size ≤ 20 μm as admixture to replace cement, and reserve the bottom slag with a particle size of 20 μm - 4.75 mm as fine aggregate to replace weathered fine aggregate; Pretreatment of weathered mine materials: First, process the weathered mine materials into weathered coarse aggregate and weathered fine aggregate through crushing and ball milling, then put the weathered coarse aggregate and weathered fine aggregate into the suspension of Bacillus pasteurii used for soaking the bottom slag respectively, and finally dry the weathered coarse aggregate and weathered fine aggregate by low-temperature drying method at ≤ 40 °C for standby; Preparation of microcapsules: Disperse the core material and dispersant into the solvent by ultrasonic wave, then dissolve the capsule wall material in a small amount of solvent, and slowly drip the dissolved capsule wall material into the dispersed core material solution, and continuously stir at a speed of 500 rpm. Then dissolve the catalyst in a small amount of solvent, slowly drip it into the above reaction system, and control the reaction temperature at 50 °C. Carry out polymerization reaction under stirring conditions for 2 - 4 h to form microcapsules. Finally, centrifuge and filter to separate the microcapsules at a speed of 3000 rpm, wash them with deionized water for many times, and finally carry out freeze-drying to obtain dry sodium silicate microcapsules and calcium oxide microcapsules; Preparation of self-healing concrete mixture: According to the actually obtained weights of the bottom slag with two particle sizes, increase or decrease the weights of the actually selected cement and weathered fine aggregate according to the ratio; weigh each material by mass percentage. First, dry-mix and stir the bottom slag with a particle size ≤ 20μm, 50% of the bottom slag with a particle size of 20μm - 4.75mm, 50% of the weathered coarse aggregate, 50% of the weathered fine aggregate, cement, sodium silicate microcapsules and calcium hydroxide microcapsules at a speed of 25 rpm for 1 min. Then, add the remaining 50% of the bottom slag with a particle size of 20μm - 4.75mm, 50% of the weathered coarse aggregate and 50% of the weathered fine aggregate and continue to dry-mix at a speed of 25 rpm for 1 min. Finally, add water and water reducer and wet-mix at a speed of 25 rpm for 2 min to obtain the self-healing concrete mixture; Forming and curing: Use a low-frequency vibrator to vibrate the self-healing concrete in the mold, and the vibration time ≤ 1 min. The self-healing concrete of the mine weathered material that has not been demolded is cured by covering with a film at room temperature of 23 ± 2 °C and relative humidity of 65 ± 15% for 1 d. After the self-healing concrete is cured and hardened for 1 d, it is placed in a standard curing room with indoor conditions of 20 ± 2 °C and relative humidity ≥ 95%, and the final self-healing concrete of the mine weathered material is obtained after curing for 28 d.

8. The preparation method of a self-repairing concrete for mine weathered materials according to claim 7, characterized in that In step (1), the concentration of OD600 in the Bacillus pasteurii suspension is 0.8 - 1.2, the treatment time is 3 h, and the Bacillus pasteurii suspension is fixed in the pores of the slag by physical adsorption. The soaking temperature is 20 - 30 °C and the pH is 7 - 9.

9. The preparation method of a self-repairing concrete for mine weathered materials according to claim 7, characterized in that In step (2), the concentration of OD600 in the Bacillus pasteurii suspension is 0.8 - 1.2, the calcium source concentration is 0.5 - 1 mol / L, the treatment time is 7 - 10 d, and the soaking temperature is 20 - 30 °C; the weathered fine aggregate is soaked and treated with the Bacillus pasteurii suspension. The concentration of OD600 in the Bacillus pasteurii suspension is 0.8 - 1.2, the calcium source concentration is 0.5 - 1 mol / L, the treatment time is 4 - 7 d, the soaking temperature is 20 - 30 °C, and the pH is 7 - 9.

10. The preparation method of a self-repairing concrete for mine weathered materials according to claim 7, characterized in that In the Bacillus pasteurii suspension described in step (2), yeast extract is also added, and the yeast extract includes one or any several of amino acids, peptides, vitamins, nucleotides, carbohydrates and minerals.

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