A method for repairing concrete cracks by microbial induced calcium carbonate precipitation using a renewable calcium source and modified zeolite powder

Abstract

The application discloses a method for repairing concrete cracks by using a regenerated calcium source and modified zeolite powder through microbial induction calcium carbonate precipitation, and the method is characterized in that a regenerated calcium source from solid waste is used for treatment to obtain a repair liquid containing calcium ions, and the repair liquid is applied in MICP for repairing concrete cracks, so that the repaired cracks have good anti-permeability, the generated precipitates have good consolidation capacity, and the crystal morphology is also good. The zeolite powder used in the application contains active silicon dioxide and silicon trioxide, can react with the hydration product calcium hydroxide of cement to generate cementitious material, and improves the cementation capacity of MICP. The modified zeolite of sodium chloride and calcium chloride has greater ion exchange capacity, and can adsorb ammonia nitrogen generated due to MICP.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete crack repair, and particularly relates to a method for repairing concrete cracks by using regenerated calcium sources and modified zeolite powder through microbial induction of calcium carbonate precipitation. BACKGROUND

[0002] Concrete is widely used in a series of civil engineering such as houses, bridges, roads, water conservancy, water transportation and the like due to its high compressive strength, good durability, low cost and the like. However, in the construction and service process of concrete structures, microcracks or local defects are inevitably generated in the interior or surface of concrete due to the influence of factors such as temperature and humidity changes, plastic deformation, dry shrinkage, external load, steel corrosion, multi-factor coupling and the like, which reduces the integrity and durability of the concrete structure, and even leads to disastrous events, threatening the safety of people's lives and property. Traditional concrete crack repair methods include surface repair method, grouting method, concrete replacement method, filling method and the like, but these methods still have great problems in repair effect, economy and environmental protection and the like.

[0003] Therefore, it is necessary to develop a new type of economic concrete crack repair technology. SUMMARY

[0004] The present application provides a method for repairing concrete cracks by using regenerated calcium sources and modified zeolite powder through microbial induction of calcium carbonate precipitation, and the zeolite powder used in the present application contains a certain amount of active silicon dioxide and silicon trioxide, which can react with the hydration product calcium hydroxide of cement to generate cementitious material and improve the cementing ability of MICP. The present application realizes the above-mentioned purpose through the following technical scheme:

[0005] A method for repairing concrete cracks by using regenerated calcium sources and modified zeolite powder through microbial induction of calcium carbonate precipitation, comprising the following steps:

[0006] S1: Preparation of culture solution: the culture solution is CASO+urea culture medium: peptone 5.0±0.5g / L, beef extract 3.0±0.3g / L, urea 20.0±2g / L, distilled water 1.0L, and the pH value is 7.0±0.5;

[0007] S2: Preparation of bacterial solution: after the Bacillus pasteurii is activated by a plate, the bacterial species are inoculated into the culture solution obtained in step S1, and after the inoculation of the bacterial species is completed, the shaking box is placed for shaking, the temperature is set to 32-38℃, the rotation speed is set to 120-170rpm, and continuous culture is carried out for 18-24 hours;

[0008] S3: Preparation of regenerated calcium source nutrient solution: Eggshell powder, limestone powder, and steel slag are used as regenerated calcium sources, and acid is used to dissolve them in a certain proportion. After the regenerated calcium source is completely dissolved, the mixture is placed in an oscillation box and oscillated for 6 to 12 hours; after the oscillation is completed, the mixture is centrifuged in a centrifuge. After the centrifugation is completed, the supernatant is collected and the pH is adjusted to 7.0 to 7.5 to obtain the dissolved regenerated calcium source; the above solution is diluted to obtain a calcium source with a calcium ion concentration of 0.25 mol / L, and 0.25 mol / L of urea is dissolved to obtain a nutrient solution for bioremediation of concrete cracks;

[0009] S4: Preparation of modified zeolite powder: The zeolite powder is composite-modified using salt and surfactant. The specific modification method is as follows: a certain amount of surfactant and salt are weighed and dissolved in 1L of deionized water, and then a certain amount of zeolite powder is added. The mixture is stirred at 30-40°C for 6 hours. After centrifugation, it is washed with deionized water three times and dried at 60-65°C.

[0010] S5: Preparation of repair solution: zeolite powder, sand and bacterial solution are uniformly stirred in a certain proportion to prepare a first mixed solution; calcium source solution and urea solution are mixed in a volume ratio of 1:1 to prepare a second mixed solution;

[0011] S6: Grouting to repair concrete cracks: Use grouting equipment to repair concrete cracks by grouting.

[0012] A further solution is that in step S1, the prepared nutrient solution is sterilized at high temperature, the temperature of the high temperature sterilization is 121°C±1°C, and the high temperature sterilization time is 15±5 minutes.

[0013] A further solution is that in step S3, the acid is acetic acid, nitric acid and hydrochloric acid, and the centrifuge speed is 5500 rpm to 6500 rpm;

[0014] The mass fraction of the acetic acid solution is 10% to 50%, and the mass ratio of the regenerated calcium source to the acid is 1:2 to 1:6.

[0015] A further solution is that in step S4, the salt solution is sodium chloride or calcium chloride; in the process of modifying natural zeolite with salt, Na + , Ca 2+ The original Mg in the zeolite pores 2+ The metal ions undergo ion exchange reaction, and the modified zeolite contains more Na + , Ca 2+ , expanding the zeolite pores and increasing the ion exchange capacity.

[0016] The concentration of the sodium chloride and calcium chloride solution is 1-2.5 mol / L; the surfactant is one or more of cetyltrimethylammonium bromide, bromohexadecylpyridine and chitosan; the surfactant modification is to form a single layer or multiple layers of load on the surface of the zeolite powder, so that the negative charge on the surface of the zeolite powder is exchanged into positive charge, and more microorganisms with negative ions can be adsorbed to become the nucleation point of the mineralized calcium carbonate of the microorganisms.

[0017] The amount of the surfactant is 50-80% of the mass of the zeolite; and the zeolite content is 10-30 g.

[0018] The zeolite powder is selected to have a particle size of 200-250 mesh.

[0019] In the step S5, the first mixed solution is prepared by mixing 50-100 parts of the zeolite powder, 10-100 parts of sand and 60-200 parts of the bacterial solution.

[0020] The second mixed solution is the regenerated calcium source nutrient solution prepared in S3; and the filler sand is selected to have a particle size of 150-200 mesh.

[0021] In the step S6, the grouting method comprises the following steps: first, the air compressor is used to remove the scattered layer, dust and dirt on the concrete matrix at the crack occurrence position at a pressure of 0.5-0.8 MPa; the grouting hole is arranged at the position where the crack width is greater than 0.2 mm or the crack is staggered or penetrated; the center hole of the grouting hole is aligned with the crack; a repair point is arranged every 30-50 cm; the grouting components are injected into the grouting nozzle through the grouting pipe in batches to fill the crack; after the grouting is completed, the grouting center is blocked by the sealing plug to prevent the grouting components from overflowing; after the grouting components in the crack are "initially set", the grouting nozzle is removed.

[0022] The mixed solution 1 is injected into the concrete crack by using the grouting equipment at a pressure of 0.3-0.5 MPa; when the grouting amount reaches the set value, the grouting is stopped, but the pressure is maintained for 5-10 min; then the mixed solution 2 is injected into the concrete crack by using the grouting equipment at a pressure of 0.2-0.3 MPa; when the grouting amount reaches the set value, the grouting is stopped, but the pressure is maintained for 10-15 min; after standing for 0.5-1 h, the above grouting steps are repeated; until a large amount of liquid overflows, the grouting is completed.

[0023] The grouting amount set value is related to the size and number of the concrete crack, and is 50-150 ml.

[0024] The present application has the following beneficial effects:

[0025] 1) The present application uses solid waste-derived regenerated calcium sources for treatment to obtain a calcium ion-containing repair solution, which is applied in MICP repair of concrete cracks. The repaired cracks have good anti-permeability, and the generated precipitates also have good consolidation ability and good crystal morphology.

[0026] 2) The zeolite powder used contains active silicon dioxide and silicon dioxide, which can react with the cement hydration product calcium hydroxide to generate cementitious substances, thereby improving the cementation ability of MICP.

[0027] 3) The modified zeolite with sodium chloride and calcium chloride has greater ion exchange capacity and can adsorb ammonia nitrogen generated due to MICP.

[0028] 4) According to the Gibbs-Tompson crystal nucleation theory, there is a critical size when the crystal nucleates. Nanocrystals smaller than the size tend to dissolve, and the nucleus larger than the size can continue to grow stably. The zeolite modified by the surfactant carries positive electricity and can enrich the negative microbial cells. The nucleation probability of calcium carbonate crystals is greatly increased, and the calcium carbonate crystals are more compact and stable.

[0029] 5) The price of chemical analysis of calcium commonly used in the technology of microbial-induced calcium carbonate precipitation for repairing concrete is about 40-60 yuan / kg. Eggshell powder belongs to kitchen garbage; limestone powder is a byproduct in the process of generating gravel and stone chips; and steel slag is a byproduct in the steelmaking process. The application of the three to the MICP technology is the secondary utilization of solid waste, which has good economic and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1a The figure is the morphology characterization of calcium carbonate precipitate obtained by using eggshell powder as a regenerated calcium source.

[0032] Figure 1b The figure is the morphology characterization of calcium carbonate precipitate obtained by using limestone powder as a regenerated calcium source.

[0033] Figure 1c The figure is the morphology characterization of calcium carbonate precipitate obtained by using steel slag as a regenerated calcium source.

[0034] Figure 2a The figure is the transmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained by using eggshell powder as a regenerated calcium source.

[0035] Figure 2bTransmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained with eggshell powder as a source of recycled calcium.

[0036] Figure 3a Transmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained with limestone powder as a source of recycled calcium.

[0037] Figure 3b Transmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained with limestone powder as a source of recycled calcium.

[0038] Figure 4a Transmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained with steel slag as a source of recycled calcium.

[0039] Figure 4b Transmission electron microscope image of the surface morphology of calcium carbonate precipitate obtained with steel slag as a source of recycled calcium.

[0040] Figure 5a Surface image of the test specimen before repair with eggshell powder as a source of recycled calcium.

[0041] Figure 5b Surface image of the test specimen after repair with eggshell powder as a source of recycled calcium.

[0042] Figure 5c Surface image of the test specimen before repair with limestone powder as a source of recycled calcium.

[0043] Figure 5d Surface image of the test specimen after repair with limestone powder as a source of recycled calcium.

[0044] Figure 5e Surface image of the test specimen before repair with steel slag as a source of recycled calcium.

[0045] Figure 5f Surface image of the test specimen after repair with steel slag as a source of recycled calcium.

[0046] Figure 6 Change in the permeability coefficient of the test specimen after repair of the mortar with eggshell powder, limestone powder and steel slag as sources of recycled calcium. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0048] Micro cracks often exist in concrete, and crack propagation usually experiences three stages: crack initiation, stable propagation and unstable fracture. The crack propagation is accompanied by energy change, and a large amount of energy is required for the crack to propagate through the coarse aggregate. Therefore, the crack propagation in ordinary concrete usually occurs in the mortar and mortar-aggregate interface transition zone, and the material has been damaged without reaching the energy required to develop through the coarse aggregate. In order to evaluate the effect of the embodiment, the influence of the coarse aggregate is eliminated, and the mortar specimen is used in the embodiment.

[0049] Preparation of specimen and crack:

[0050] The mixing ratio of the specimen is sand: water: cement = 5:1:2.5, and a steel bar with a diameter of 7 mm is added during the molding process to facilitate the subsequent pre-cracking. The specimen is cured for 28 days under standard conditions (temperature 20±2℃, relative humidity 95±3%).

[0051] After the end of the curing, the specimen is taken out of the curing room and the surface moisture is wiped off with a dry towel, and the crack is pressed on the bending testing machine by using the three-point pressure method. The specimen without pre-cracking is used as the control group for the penetration test.

[0052] Example 1

[0053] The method of the present application comprises the following steps:

[0054] 1. Preparation of culture solution:

[0055] Select 5.0±0.5g / L of proteose peptone, 3.0±0.3g / L of beef extract, 20.0±2g / L of urea, and 1.0L of distilled water to obtain the culture solution, and adjust the pH value of the culture solution to 7.0±0.5; after high-temperature sterilization of the prepared culture solution, ultraviolet sterilization is performed. The high-temperature sterilization temperature is 120±5℃, and the sterilization time is 20±5min.

[0056] 2. Preparation of bacterial solution:

[0057] After the plate activation of Bacillus pasteurii, the bacterial strain is inoculated into the culture solution obtained in step S1, and after the inoculation of the bacterial strain is completed, the shaking incubator is placed for shaking, the temperature is set to 32-38℃, the rotation speed is set to 120-170rpm, and continuous culture is carried out for 18-24 hours.

[0058] 3. Preparation of regenerated calcium source nutrient solution:

[0059] Dissolve the solid waste with 20% acetic acid in a mass ratio of 1:2-1:4, and then put the regenerated calcium source into a shaking box for 3-12 hours after the complete dissolution of the regenerated calcium source; centrifuge the solution at a speed of 6000 rpm, and then take the supernatant, adjust the pH to 7.0-7.5, and obtain the dissolved regenerated calcium source, and then determine the calcium ion concentration after dissolution by using a calcium ion meter, as shown in Table 1.

[0060] Table 1 Calcium ion concentration after dissolution of limestone powder calcium source and 20% acetic acid solution in different proportions

[0061]

[0062] As can be seen from Table 1, the limestone powder is basically dissolved to the maximum amount after 12 hours, and the maximum calcium ion concentration is 0.7665 mol / L at a ratio of 1:2. Dilute the above solution to obtain a calcium source with a calcium ion concentration of 0.25 mol / L, and then dissolve 0.25 mol / L urea to obtain a bioremediation mortar crack nutrient solution.

[0063] 4. Preparation of modified zeolite powder:

[0064] Dissolve 7g of cetyltrimethylammonium bromide and 60g of sodium chloride in 1L of deionized water, and then add 10g of 250 mesh zeolite powder, and stir at 30-40℃ for 6h. After centrifugation, wash with deionized water for 3 times, and dry at 60-65℃.

[0065] 5. Preparation of repair solution:

[0066] Mix the zeolite powder, 200 mesh sand and the bacterial solution in a proportion of 50:50:100 to obtain a mixed solution 1; and mix the urea powder calcium source solution in a volume ratio of 1:1 to obtain a mixed solution 2.

[0067] 6. Grouting repair of mortar cracks:

[0068] (1) First, use an air compressor to remove scattered layers, dust, dirt and other impurities from the mortar matrix at the crack site at a pressure of 0.8MPa;

[0069] (2) Set a grouting hole at the position where the crack width is greater than 0.2mm or the crack is staggered and penetrated, and the center hole of the grouting hole should be aligned with the crack, and a repair point should be set every 30-50cm;

[0070] (3) Inject 100ml of mixed solution 1 into the mortar crack through the grouting equipment at a pressure of 0.5MPa, stop grouting, but maintain the pressure for 5-10min;

[0071] (4) through the grouting equipment to 0.3MPa pressure 100ml mixed solution 2 into the mortar crack, then maintain the pressure 10-15min, stand 0.5-1h;

[0072] (5) repeat the above (3)-(4) grouting step; until there is a large amount of liquid overflow, grouting end;

[0073] (6) with the sealing plug grouting center dead, prevent grouting component overflow;

[0074] (7) after the crack in the grouting component "initial setting", remove the grouting nozzle.

[0075] As shown in Figure 1b , the limestone powder as the repair group of the calcium source produces calcium carbonate precipitate after repair calcite (C represents calcite) and vaterite (V represents vaterite).

[0076] As shown in Figure 3, the limestone powder as the repair group of the calcium source produces calcium carbonate precipitate after repair calcite, and the crystal arrangement is compact.

[0077] As shown in Figure 5c , Figure 5d , the limestone powder as the repair group of the calcium source is compared before and after the crack repair, Figure 5c is the photo of the crack before repair, Figure 5d is the photo of the crack after repair.

[0078] As shown in Figure 6 , the permeability coefficient of the mortar test piece of the repair group of the limestone powder as the calcium source is 3.79×10 -5 cm / s

[0079] Example 2

[0080] The method of the application comprises the following steps:

[0081] 1. Preparation of culture solution:

[0082] Select 5.0±0.5g / L of proteose peptone, 3.0±0.3g / L of beef extract, 20.0±2g / L of urea, and 1.0L of distilled water to obtain a culture solution, and adjust the pH value of the culture solution to 7.0±0.5; after high-temperature sterilization of the prepared culture solution, ultraviolet sterilization is performed. The high-temperature sterilization temperature is 120±5℃, and the sterilization time is 20±5min.

[0083] 2. Preparation of bacterial solution:

[0084] After the Bacillus pasteurii is activated by plate, the culture solution obtained in step S1 is inoculated with the bacterial inoculum, and after the inoculation of the bacterial inoculum is completed, the shaking incubator is placed for shaking, the temperature is set to 32-38℃, the rotation speed is set to 120-170 rpm, and the continuous culture is carried out for 18-24 hours.

[0085] 3. Preparation of the calcium source nutrient solution:

[0086] The eggshell powder is used as the calcium source, the solid waste is dissolved with 20% acetic acid at a mass ratio of 1:2-1:4, after the calcium source is completely dissolved, the solution is placed in a shaking incubator for shaking for 3-12 hours; after the shaking is completed, the solution is centrifuged by a centrifuge at a rotation speed of 6000 rpm, the supernatant is taken after the centrifugation is completed, the pH is adjusted to 7.0-7.5, and the dissolved calcium source is obtained, and then the calcium ion concentration after the dissolution is measured by a calcium ion meter, as shown in Table 2.

[0087] Table 2 Calcium ion concentration after dissolution of eggshell powder calcium source and 20% acetic acid solution at different ratios

[0088]

[0089] It can be seen from Table 2 that the eggshell powder is basically dissolved to the maximum amount after 12 hours, and the maximum calcium ion concentration is 0.6165 mol / L at a ratio of 1:2. The above solution is diluted to obtain a calcium source with a calcium ion concentration of 0.25 mol / L, and 0.25 mol / L of urea is dissolved to obtain a biological repair mortar crack nutrient solution.

[0090] 4. Preparation of modified zeolite powder:

[0091] 5g of bromohexadecylpyridine and 111g of calcium chloride are dissolved in 1L of deionized water, and then 10g of 250 mesh zeolite powder is added, and stirred at 30-40℃ for 6h. After centrifugation, the deionized water is washed 3 times, and dried at 60-65℃.

[0092] 5. Preparation of the repair solution:

[0093] The zeolite powder, 200 mesh sand and bacterial solution are uniformly stirred at a ratio of 50:50:100 to prepare a mixed solution 1; and the urea powder calcium source solution is mixed at a volume ratio of 1:1 to prepare a mixed solution 2.

[0094] 6. Grouting repair of mortar cracks:

[0095] (1) First, the scattered layer, dust, dirt and the like are removed from the mortar matrix at the crack occurrence position by using an air compressor at a pressure of 0.8 MPa;

[0096] (2) In the crack width greater than 0.2mm or is staggered, through the site where the grouting hole is set, the center hole of the grouting hole should be aligned with the crack, and a repair point is set every 30-50cm;

[0097] (3) 100ml of mixed liquid 1 is injected into the mortar crack by the grouting equipment at a pressure of 0.5MPa, the grouting is stopped, but the pressure is maintained for 5-10min;

[0098] (4) 100ml of mixed liquid 2 is injected into the mortar crack by the grouting equipment at a pressure of 0.3MPa, and then the pressure is maintained for 10-15min, and the standing time is 0.5-1h;

[0099] (5) The grouting steps (3)-(4) are repeated; until a large amount of liquid overflows, and the grouting is finished;

[0100] (6) The grouting center is blocked by a sealing plug to prevent the grouting components from overflowing;

[0101] (7) After the grouting components in the crack "initially set", the grouting nozzle is removed.

[0102] As shown in Figure 1a , the calcium carbonate precipitate produced after the repair of the repair group with eggshell powder as the regenerated calcium source is part of the vaterite (V represents vaterite).

[0103] As shown in Figure 2, the calcium carbonate produced after the repair of the repair group with eggshell powder as the regenerated calcium source is a compact hexagonal calcite and a relatively smooth litchi-shaped vaterite.

[0104] As shown in Figure 5a , Figure 5b , the repair before and after the repair of the repair group with eggshell powder as the regenerated calcium source, Figure 5a is a photo of the crack before repair, Figure 5b is a photo of the crack after repair.

[0105] As shown in Figure 6 , the permeability coefficient of the mortar test piece after the repair of the repair group with eggshell powder as the regenerated calcium source is 1.17×10 -4 cm / s

[0106] Example 3

[0107] The method of the application comprises the following steps:

[0108] 1. Preparation of culture solution:

[0109] Select protein 5.0±0.5g / L, beef extract 3.0±0.3g / L, urea 20.0±2g / L, distilled water 1.0L mixed to obtain the culture solution, and the pH value of the culture solution is adjusted to 7.0±0.5; the prepared culture solution is sterilized at high temperature and then subjected to ultraviolet sterilization. The temperature of high temperature sterilization is 120±5℃, and the sterilization time is 20±5min.

[0110] 2. Preparation of bacterial solution:

[0111] After the Bacillus pasteurii is activated by plate, the bacterial strain is inoculated into the culture solution obtained in step S1, and after the inoculation of the bacterial strain is completed, the shaking incubator is placed for shaking, the temperature is set to 32-38℃, the rotation speed is 120-170rpm, and the continuous culture is carried out for 18-24 hours.

[0112] 3. Preparation of regenerated calcium source nutrient solution:

[0113] The steel slag is used as a regenerated calcium source, the solid waste is dissolved with 20% acetic acid in a mass ratio of 1:2-1:4, after the regenerated calcium source is completely dissolved, it is placed in a shaking incubator for shaking for 3-12 hours; after the shaking is completed, the centrifuge is used for centrifugation, the rotation speed of the centrifuge is 6000rpm, after the centrifugation is completed, the supernatant is taken, the pH is adjusted to 7.0-7.5, and the dissolved regenerated calcium source is obtained, and then the calcium ion meter is used to determine the calcium ion concentration after dissolution, as shown in Table 3.

[0114] Table 3 Calcium ion concentration after dissolution of steel slag calcium source and 20% acetic acid solution in different proportions

[0115]

[0116] As can be seen from Table 3, the steel slag is dissolved for about 12h to reach the maximum dissolution amount, and the maximum calcium ion concentration is 1:2, which is 0.5021mol / L. The above solution is diluted to obtain a calcium source with a calcium ion concentration of 0.25mol / L, and then 0.25mol / L of urea is dissolved to obtain a biological repair mortar crack nutrient solution.

[0117] 4. Preparation of modified zeolite powder:

[0118] 5g of bromohexadecyl pyridine and 111g of calcium chloride are dissolved in 1L of deionized water, then 10g of 250 mesh zeolite powder is added, and stirring is carried out at 30-40℃ for 6h. After centrifugation, deionized water is washed 3 times, and drying is carried out at 60-65℃.

[0119] 5. Preparation of repair solution:

[0120] The zeolite powder, 200 mesh sand and bacterial solution are uniformly stirred in a proportion of 50:50:100 to obtain a mixed solution 1; the urea powder and calcium source solution are mixed in a volume ratio of 1:1 to obtain a mixed solution 2.

[0121] 6. Grouting repair mortar cracks:

[0122] (1) First, the mortar matrix at the crack occurs, the scattered layer, dust, dirt, etc. with air pressure machine to remove 0.8 MPa pressure;

[0123] (2) In the crack width greater than 0.2 mm or the crack staggered, through the site set grouting hole, grouting hole center hole should be aligned with the crack, every 30-50 cm set a repair point;

[0124] (3) through the grouting equipment to 0.5 MPa pressure 100 ml mixed liquid 1 into the mortar cracks, stop grouting, but maintain pressure 5-10 min;

[0125] (4) again through the grouting equipment to 0.3 MPa pressure 100 ml mixed liquid 2 into the mortar cracks, then maintain pressure 10-15 min, 0.5-1 h;

[0126] (5) repeat the above (3)-(4) grouting steps; until a large amount of liquid overflow, grouting end;

[0127] (6) with the seal plug grouting center dead, prevent grouting components spill;

[0128] (7) after the crack grouting components "initial setting", remove the grouting nozzle.

[0129] As shown in Figure 1, the steel slag as a source of renewable calcium repair group after repair produced calcium carbonate precipitate is basically ball vaterite (V represents ball vaterite).

[0130] As shown in Figure 4, the steel slag as a source of renewable calcium repair group after repair produced calcium carbonate precipitate is ball vaterite.

[0131] As Figure 5e , Figure 5f shown, the steel slag as a source of renewable calcium repair group before and after repair comparison chart, Figure 5e is the photo of the crack before repair, Figure 5f is the photo of the crack after repair.

[0132] As Figure 6 shown, the steel slag group as a source of renewable calcium repair group after repair mortar test piece permeability coefficient is 2.9 x 10 -4 cm / s.

[0133] Among them, eggshell powder and steel slag as a source of renewable calcium repair group, after repair produced calcium carbonate precipitate is mainly ball vaterite, the crystal strength is low, loose and unstable structure, the permeability coefficient of the test piece after repair is 1.17 x 10 -4 cm / s and 2.9 x 10-4 cm / s. The main precipitated calcium carbonate after repair is blocky calcite with compact and stable crystal structure. Compared with examples 2 and 3, it has better bonding performance in the cracks, and the permeability of the repaired test piece is better, which is 3.79 x 10 -5 cm / s.

[0134] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims. In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations. Furthermore, various different embodiments of the present application can be combined in any manner, as long as it does not deviate from the idea of the present application, and it shall be considered as disclosed by the present application.

Claims

1. A method for repairing concrete cracks by using a regenerated calcium source and modified zeolite powder to induce calcium carbonate precipitation through microorganisms, characterized in that: The following steps are involved: S1: Preparation of culture medium: The culture medium is CASO+urea medium: 5.0±0.5g / L peptone, 3.0±0.3g / L beef extract, 20.0±2g / L urea, 1.0L distilled water, pH 7.0±0.5; the prepared culture medium is sterilized by high temperature and then UV sterilization; the high temperature sterilization temperature is 120±5℃, and the sterilization time is 20±5min; S2: Preparation of bacterial solution: After activating Bacillus pasteurianus on a plate, inoculate the culture solution obtained in step S1. After inoculation, place the culture in an oscillating incubator at a temperature of 32-38°C and a rotation speed of 120-170 rpm for 18-24 hours. S3: Preparation of regenerated calcium source nutrient solution: limestone powder is used as the regenerated calcium source, and solid waste and acetic acid with a mass fraction of 20% are dissolved in a mass ratio of 1:

2. After the regenerated calcium source is completely dissolved, it is placed in an oscillation box and oscillated for 3 to 12 hours; after the oscillation is completed, it is centrifuged in a centrifuge at a speed of 6000 rpm. After the centrifugation is completed, the supernatant is taken and the pH is adjusted to 7.0 to 7.5 to obtain the dissolved regenerated calcium source; the above solution is diluted to obtain a calcium source with a calcium ion concentration of 0.25 mol / L, and then 0.25 mol / L of urea is dissolved to obtain a nutrient solution for bioremediation of concrete cracks; S4: Preparation of modified zeolite powder: The zeolite powder was composite-modified using salt and surfactant. The specific modification method was as follows: 7 g of hexadecyltrimethylammonium bromide and 60 g of sodium chloride were dissolved in 1 L of deionized water, and then 10 g of 250-mesh zeolite powder was added. The mixture was stirred at 30-40°C for 6 h. After centrifugation, the mixture was washed with deionized water three times and dried at 60-65°C. S5: Preparation of repair solution: Modified zeolite powder, 200 mesh sand and bacterial solution are uniformly mixed in a ratio of 50:50:100 to prepare a first mixed solution; the biological repair concrete crack nutrient solution prepared in S3 is the second mixed solution; S6: Grouting to repair concrete cracks: Use grouting equipment to repair concrete cracks by grouting, including: 1) First, use an air compressor at a pressure of 0.8MPa to sweep away the loose layer, dust and dirt on the mortar base where the cracks occur; 2) Set grouting holes where the crack width is greater than 0.2mm or where the cracks intersect or penetrate. The center hole of the grouting hole should be aligned with the crack, and a repair point should be set every 30 to 50 cm. 3) Inject 100 ml of the first mixed solution into the mortar cracks at a pressure of 0.5 MPa through the grouting equipment, stop grouting, but maintain the pressure for 5 to 10 minutes; 4) Then, inject 100 ml of the second mixed solution into the mortar cracks at a pressure of 0.3 MPa using the grouting equipment, then maintain the pressure for 10 to 15 minutes and let it stand for 0.5 to 1 hour; 5) Repeat the above steps 3) and 4) until a large amount of liquid overflows and the grouting is completed; 6) Use a sealing plug to block the grouting center to prevent the grouting components from overflowing; 7) After the grouting components in the cracks have initially solidified, remove the grouting nozzle.

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