CN112876154A - Crack repairing method - Google Patents
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- CN112876154A CN112876154A CN202110068781.8A CN202110068781A CN112876154A CN 112876154 A CN112876154 A CN 112876154A CN 202110068781 A CN202110068781 A CN 202110068781A CN 112876154 A CN112876154 A CN 112876154A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/021—Ash cements, e.g. fly ash cements ; Cements based on incineration residues, e.g. alkali-activated slags from waste incineration ; Kiln dust cements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0203—Arrangements for filling cracks or cavities in building constructions
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Abstract
The invention relates to the technical field of repair of building materials, in particular to a method for repairing cracks. The method for repairing the crack comprises the following steps: A) carrying out high-temperature treatment on the ultrafine fly ash to obtain pretreated fly ash; B) mixing the bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture; the strains contained in the bacterial liquid comprise penicillium chrysogenum; C) uniformly mixing the fly ash-fungus bacterial sludge mixture with a nutrient solution, and grouting and filling into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks; the nutrient solution is a mixed solution of calcium salt and urea. The repairing method provided by the invention can be used for repairing the concrete material cracks, and the repaired material has better mechanical property.
Description
Technical Field
The invention relates to the technical field of repair of building materials, in particular to a method for repairing cracks.
Background
Concrete is one of the most widely used building materials, and has been widely accepted due to its advantages of high compressive strength, low cost, good durability, etc. However, the concrete has low tensile strength and brittle property, and cracks are inevitably generated under the influence of temperature stress, load and other factors. The crack makes moisture, chloride ion, oxygen etc. in the air get into inside the concrete, and the invasion corrodes the reinforcing bar, damages the concrete, and then influences the durability and the life of concrete.
The common repairing methods for existing cracks include cement grouting, surface coating with hydrophobic materials, crack filling with epoxy mortar, and the like. The method has the advantages of complex process, higher cost, low efficiency and easy secondary damage to environmental pollution. Such as: the surface coating can not go deep into the crack, and when the coating material is worn or has pores, the coating material still can affect the internal steel bar component through the original crack. And the polyurethane and the epoxy resin have poor ageing resistance and are difficult to be compatible with cement, so that the real repair is difficult to achieve.
In recent years, a technique of repairing cracks using calcium carbonate induced by a specific microorganism has been attracting much attention. The principle is that microorganisms can decompose nutrients to produce carbonate ions and ammonium ions. When the surroundings are enriched with calcium ions, calcium carbonate and calcium ions will form calcium carbonate crystals. Meanwhile, the pH value around the concrete is increased due to the increase of the concentration of ammonium ions, and calcium carbonate is continuously deposited in the alkaline environment to repair concrete cracks. However, most of the current research on microbial crack repairing technology focuses on prokaryotes, such as common bacillus octaplensis, which has poor environmental adaptability and tolerance and is difficult to survive at a high pH (9 or higher) or under-oxygen condition; meanwhile, the content of extracellular enzymes of bacteria in unit biomass is low, so that the generation and deposition of calcium carbonate are directly influenced, and the repairing effect is further influenced; furthermore, the physiological structure makes it difficult for bacteria to attach firmly to the tough basal surfaces of the loading material or the inner walls of the cracks, thereby affecting the repairing effect.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method for repairing a crack, which can be used for repairing a crack of a concrete material, and the repaired material has excellent mechanical properties.
The invention provides a method for repairing a crack, which comprises the following steps:
A) carrying out high-temperature treatment on the ultrafine fly ash to obtain pretreated fly ash;
B) mixing the bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture; the strains contained in the bacterial liquid comprise penicillium chrysogenum;
C) uniformly mixing the fly ash-fungus bacterial sludge mixture with a nutrient solution, and grouting and filling into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks; the nutrient solution is a mixed solution of calcium salt and urea.
Preferably, the particle size of the ultrafine fly ash is less than 50 μm;
the specific surface area of the ultrafine fly ash is 6100-8025 cm2/g。
Preferably, the temperature of the high-temperature treatment is 120-150 ℃, and the time of the high-temperature treatment is 1-5 h;
after the high-temperature treatment, the method further comprises the following steps: and cooling to room temperature.
Preferably, the mass ratio of the bacterial liquid to the pretreated fly ash is 2: 1.
preferably, the cell density OD600 of the strain in the bacterial liquid is 108～109cells/mL。
Preferably, the bacterial liquid is prepared according to the following method:
inoculating the penicillium chrysogenum into a sterilized culture medium in an aseptic environment, and culturing for 24-36 h in a shaking incubator at 25-35 ℃ to obtain a bacterial liquid; the rotating speed of the shaking incubator is 150-200 rps.
Preferably, the culture medium comprises a carbon source, inorganic salts and water, or the culture medium comprises a nitrogen source, inorganic salts and water;
the carbon source comprises sucrose, lactose, caramel, glucose, starch hydrolysis sugar or saccharification liquid; the DE value of the saccharification liquid is not less than 50%;
the nitrogen source comprises peptone, yeast extract, corn steep liquor, refined cottonseed cake powder, bran, ammonium sulfate or ammonia water;
the inorganic salt comprises one or more of magnesium sulfate, potassium phosphate, sodium sulfate, magnesium nitrate, sodium chloride and sodium nitrate;
the sterilized culture medium is prepared according to the following method:
adjusting the pH value of the culture medium to 7.0-9.0 by adopting NaOH solution, and then sterilizing by using a high-pressure steam sterilization pot;
the sterilization temperature is 120-150 ℃, and the sterilization time is 15-30 min.
Preferably, the calcium salt comprises CaCl2、Ca(NO3)2And Ca (CH)3COO)2One or more of the above;
in the nutrient solution, Ca2+The concentration is 0.5-1.0 mol/L;
the mass ratio of the fly ash-fungus bacterial sludge mixture to the nutrient solution is 1: 1.
preferably, the width of the slit does not exceed 5 mm.
Preferably, the grouting speed is 10-12 mL/h.
The invention provides a method for repairing a crack, which comprises the following steps: A) carrying out high-temperature treatment on the ultrafine fly ash to obtain pretreated fly ash; B) mixing the bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture; the strains contained in the bacterial liquid comprise penicillium chrysogenum; C) uniformly mixing the fly ash-fungus bacterial sludge mixture with a nutrient solution, and grouting and filling into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks; the nutrient solution is a mixed solution of calcium salt and urea. In the invention, the penicillium chrysogenum is metabolized in a humid environment to generate urease, and the urease hydrolyzes urea to generate ammonium ions and carbonate ions. As the organic matter with negative charges at the interface of the fungal cell membrane continuously chelates calcium ions, and the calcium ions and carbonate ions generated by urea hydrolysis slowly mineralize and deposit calcium carbonate crystals with a gelling effect. The role of the fungus in this process is not only to produce urease, but also to provide nucleation sites for the deposition of calcium carbonate. Meanwhile, the fly ash fine particle medium loaded with the fungi is adhered together under the cementing action of calcium carbonate to form a firm and stable repairing material.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for repairing a crack, which comprises the following steps:
A) carrying out high-temperature treatment on the ultrafine fly ash to obtain pretreated fly ash;
B) mixing the bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture; the strains contained in the bacterial liquid comprise penicillium chrysogenum;
C) uniformly mixing the fly ash-fungus bacterial sludge mixture with a nutrient solution, and grouting and filling into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks; the nutrient solution is a mixed solution of calcium salt and urea.
The invention firstly carries out high-temperature treatment on the ultrafine fly ash to obtain the pretreated fly ash.
In certain embodiments of the invention, the ultrafine fly ash has a particle size <50 μm. In certain embodiments, the 45 μm oversize of the ultrafine fly ash is 3.2%. In certain embodiments, the 30 μm oversize of the ultrafine fly ash is 2.8%.
In some embodiments of the invention, the specific surface area of the ultrafine fly ash is 6100-8025 cm2(ii) in terms of/g. In certain embodiments, the ultrafine fly ash has a specific surface area of 6301cm2G or 7340cm2/g。
In certain embodiments of the invention, the ultrafine fly ash has a loss on ignition of less than 2.5, which indicates that the fly ash has a higher carbon content, affecting the loading efficiency and the strength after crack repair. In certain embodiments, the ultrafine fly ash has a loss on ignition of 1.74 or 2.38.
The source of the ultrafine fly ash is not particularly limited, and in some embodiments of the present invention, the ultrafine fly ash is obtained by ball milling fly ash with a ball mill and then sorting fly ash with a cyclone separator. The source of the fly ash is not particularly limited, and the fly ash can be fly ash crude ash of a power plant or can be generally sold in the market. The ultrafine fly ash has large specific surface area and large internal holes, and is beneficial to the adsorption and survival of fungi.
In some embodiments of the invention, the temperature of the high-temperature treatment is 120-150 ℃, and the time of the high-temperature treatment is 1-5 hours. In certain embodiments of the invention, the high temperature treatment is performed in an oven.
The invention carries out high-temperature treatment on the ultrafine fly ash, and has three main functions: (1) unburned carbon in the fly ash can be removed, and the loss on ignition of the fly ash is further reduced. (2) And (4) carrying out primary sterilization, effectively removing external fungi carried by the ultrafine fly ash, and further ensuring the purity of the loaded fungi. (3) Improves the whiteness of the fly ash and widens the application range. The residual carbon of the fly ash after high-temperature treatment is basically burnt out, so that the color of the fly ash is changed from gray or grey white before combustion into pink or light pink, and the application range of the crack healant taking the fly ash as a carrier is further expanded.
In some embodiments of the present invention, after the high temperature treatment, the method further comprises: and cooling to room temperature. The cooling method of the present invention is not particularly limited, and natural cooling may be used.
And after the pretreated fly ash is obtained, mixing a bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture.
In the invention, the strains contained in the bacterial liquid comprise penicillium chrysogenum. In some embodiments of the invention, the bacterial strain in the bacterial liquid has a cell density OD600 of 108～109cells/mL. In some embodiments, the bacterial species in the bacterial solution has a cell density OD600 of 2.7X 108cells/mL or 8.3X 108cells/mL. In some embodiments of the invention, the cells of the penicillium chrysogenum are rod-shaped, have a length of 4-6 μm, have a round spore, and have a diameter of 2.5 to 3 μm. In certain embodiments of the invention, the flavopenicillin producing bacteria are purchased from the China center for culture Collection of marine microorganisms.
In some embodiments of the present invention, the mass ratio of the bacterial liquid to the pretreated fly ash is 2: 1.
in some embodiments of the invention, the bacterial liquid is prepared according to the following method:
inoculating the penicillium chrysogenum into a sterilized culture medium in an aseptic environment, and culturing for 24-36 h in a shaking incubator at 25-35 ℃ to obtain a bacterial liquid.
In certain embodiments of the invention, the temperature of the culture is 25 ℃ or 30 ℃. In certain embodiments of the invention, the incubation time is 24h or 30 h.
In some embodiments of the invention, the rotation speed of the shaking incubator is 150-200 rps. In certain embodiments, the rotation speed of the shake incubator is 170rps or 200 rps.
In certain embodiments of the invention, the medium comprises a carbon source, inorganic salts, and water, or the medium comprises a nitrogen source, inorganic salts, and water. The preparation method of the culture medium is not particularly limited, and the culture medium can be obtained by uniformly mixing the carbon source, the inorganic salt and the water, or by uniformly mixing the nitrogen source, the inorganic salt and the water.
In certain embodiments of the invention, the carbon source comprises sucrose, lactose, caramel, glucose, amylolytic sugars, or saccharification liquid. In certain embodiments of the invention, the DE value of the saccharification liquid is not less than 50%.
In certain embodiments of the invention, the nitrogen source comprises peptone, yeast extract, corn steep liquor, refined cottonseed meal, bran, ammonium sulfate, or ammonia water.
In certain embodiments of the invention, the inorganic salt comprises one or more of soluble metal salts. The soluble metal salt can be one or more of nitrate, sulfate, chloride and phosphate of metal. The metal in the soluble metal salt can be one or more of calcium, magnesium, potassium and sodium. In certain embodiments of the invention, the inorganic salt comprises one or more of magnesium sulfate, potassium phosphate, sodium sulfate, magnesium nitrate, sodium chloride, and sodium nitrate.
In certain embodiments of the present invention, the water is deionized water, which is generally commercially available.
In some embodiments of the invention, the ratio of the carbon source, the inorganic salt and the water in the culture medium is 10-50 g: 1-5 g: 1L of the compound. In certain embodiments, the medium comprises a carbon source, inorganic salts, and water in a ratio of 30.0 g: 4.0 g: 1L of the compound.
In some embodiments of the invention, the ratio of the nitrogen source, the inorganic salt and the water in the culture medium is 10-50 g: 1-5 g: 1L of the compound. In certain embodiments, the ratio of the amount of nitrogen source, inorganic salts and water in the medium is 10.0 g: 1.0 g: 1L of the compound.
In certain embodiments of the invention, the pH of the medium is 6.0 to 7.0. In certain embodiments, the pH of the medium is 6.5 or 6.8.
In certain embodiments of the invention, the sterilized medium is prepared by the following method:
adjusting the pH value of the culture medium to 7.0-9.0 by adopting alkali liquor, and then sterilizing by using a high-pressure steam sterilization pot.
In certain embodiments of the invention, the lye is an aqueous solution of NaOH. The concentration of the alkali solution is not particularly limited, and in some embodiments of the present invention, the concentration of the alkali solution is 0.5% to 1.5%, preferably 0.5% to 1%.
In certain embodiments of the invention, the pH of the medium is adjusted to 8.0 or 9.0 using an alkaline solution.
In some embodiments of the invention, the sterilization temperature is 120-150 ℃ and the time is 15-30 min. In certain embodiments, the sterilization temperature is 120 ℃ or 150 ℃. In certain embodiments, the sterilization time is 20min or 15 min.
In some embodiments of the invention, the mixing of the inoculum with the pretreated fly ash is performed in a sealed container. In some embodiments of the present invention, after the pretreated fly ash is immersed in the bacterial liquid, the method further includes: the air in the sealed container is pumped to form a vacuum environment. The invention can further pump and adjust the air in the sealed container to form a vacuum environment, and can furthest exhaust the air in the pores of the fly ash, thereby leading the bacterial liquid and the pretreated fly ash particles to be fully fused. The vacuum degree of the vacuum environment is not particularly limited in the present invention, and may be a vacuum degree of a vacuum environment known to those skilled in the art.
In certain embodiments of the invention, the time of standing in a vacuum environment is 0.5h or 1 h.
In certain embodiments of the invention, the cell density OD600 of the chrysogenin loaded with the fly ash-fungal sludge mixture is 108～109cells/mL. In certain embodiments, the fly ash-fungal sludge mixture-loaded xanthocillin-producing bacteria has a cell density OD600 of 1.83 x 108cells/mL or 5.37X 108cells/mL。
And after the fly ash-fungus mud mixture is obtained, uniformly mixing the fly ash-fungus mud mixture and the nutrient solution to obtain grouting liquid, and grouting and filling the grouting liquid into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks.
In the invention, the nutrient solution is a mixed solution of calcium salt and urea.
In certain embodiments of the invention, the calcium salt comprises CaCl2、Ca(NO3)2And Ca (CH)3COO)2One or more of them.
In certain embodiments of the invention, the nutrient solution comprises Ca2+The concentration is 0.5 to 1.0 mol/L. In certain embodiments, the nutrient solution comprises Ca2+The concentration is 0.5mol/L or 1.0 mol/L.
In certain embodiments of the invention, the mass ratio of calcium salt to urea is 1: 1.
in certain embodiments of the present disclosure, the mass ratio of the fly ash-fungal bacterial sludge mixture to the nutrient solution is 1: 1.
in some embodiments of the present invention, before filling the crack with the grout, the method further comprises:
hydrating and drying the fracture surface, cooling to room temperature, and then smearing grouting liquid on the dried fracture surface.
In certain embodiments of the invention, the drying method after hydration is oven drying. In some embodiments of the invention, the drying temperature is 70-80 ℃, and the drying time is 22-26 h. In certain embodiments, the temperature of the oven drying is 75 ℃. In certain embodiments, the drying time is 24 hours. After hydration, drying and cooling are carried out, and the grouting liquid can be adsorbed on the fracture surface by depending on the matrix suction as much as possible.
In certain embodiments of the invention, the width of the slit does not exceed 5 mm.
In certain embodiments of the invention, the fractures may be fractures of concrete materials, in particular may be fractures of cement mortar materials.
In some embodiments of the present invention, the grouting speed is 10-12 mL/h. In certain embodiments, the grouting rate is 10 mL/h.
In some embodiments of the present invention, the grouting time is 12-36 hours. In certain embodiments, the grouting time is 24 hours.
In the invention, the penicillium chrysogenum is metabolized in a humid environment to generate urease, and the urease hydrolyzes urea to generate ammonium ions and carbonate ions. As the organic matter with negative charges at the cell membrane interface of the penicillium chrysogenum continuously chelates calcium ions, and slowly mineralizes and deposits calcium carbonate crystals with a gelling effect with carbonate ions generated by urea hydrolysis. The role of the penicillium chrysogenum in this process is not only to generate urease, but also to provide nucleation sites for the deposition of calcium carbonate. Meanwhile, the fly ash fine particle medium loaded with the penicillium chrysogenum is adhered together under the cementing action of calcium carbonate to form a firm and stable repairing material.
The source of the above-mentioned raw materials is not particularly limited in the present invention, and may be generally commercially available.
In order to further illustrate the present invention, the following detailed description of a method for repairing a crack provided by the present invention is provided with reference to the following examples, which should not be construed as limiting the scope of the present invention.
The starting materials used in the following examples are all generally commercially available.
Example 1
1. Preparation of a round cake sample:
round cake cement mortar test pieces (diameter 10cm, thickness 3cm), cement label is P.O42.5, mix proportion is water cement ratio 0.5, and the mass ratio of standard sand, cement and water is 1395: 537: 268. the method comprises the steps of forming by using a cylindrical steel film with the diameter of 10cm, removing a mold after 3 days for standard maintenance, cutting a test piece into a cylinder with the thickness of 3cm on a concrete cutting machine on the 7 th day, and then cutting a nick with the depth of 0.5cm and the width of 3mm on a rock cutting machine along the diameter. And finally, applying bending load by using an MTS multifunctional testing machine to fracture the test piece along the nicks, splicing the fractured test piece again, wherein the width of the crack at the bottom of the test piece is 0.4 mm. And curing in water for 100 days to hydrate the cross section of the test piece.
2. The coarse ash of a power plant in Zhejiang river is selected and ground and separated by an HLMX superfine vertical mill (Guilin hong distance) to obtain the superfine fly ash. The measurement shows that the 45 mu m sieve residue of the fly ash is 3.2 percent, and the specific surface area is 6301cm2The loss on ignition is 1.74.
3. And (3) drying 500g of ultrafine fly ash in a drying box at the drying temperature of 120 ℃ for 4 h. And (4) drying and cooling to room temperature to obtain the pretreated fly ash.
4. The selected penicillium chrysogenum is purchased from China ocean microbial strain preservation management center, the cell is rod-shaped (length is 4-6 μm), and the spore is circular (diameter is 2.5-3 μm). The culture medium is carbon source solution containing inorganic salt, and comprises sucrose 30.0g and NaNO33.0g、K3PO41.0g of distilled water (1L), and the initial pH value thereof was 6.5. Adjusting pH of the culture medium to 8.0 with sodium hydroxide water solution (mass concentration of 0.5%), and sterilizing at 120 deg.C for 20min with high pressure steam sterilizing kettle. Inoculating in a sterile environment, and culturing in a shaking incubator (25 ℃, 170rps) for 24h to obtain a bacterial liquid. After the bacterial liquid is kept still for 24 hours, OD600 is 2.7 multiplied by 108cells/mL。
5. The nutrient solution is 1L of CaCl2Mixed solution of urea and Ca2+The concentration is 0.5mol/L, the CaCl is2And urea in a mass ratio of 1: 1.
6. mixing the pretreated fly ash obtained in the step 3 with the bacterial liquid obtained in the step 4 according to a mass ratio of 1: 2, carrying out vacuum impregnation treatment for 0.5h after mixing to obtain a fly ash-fungal bacterial sludge mixture, and measuring that the OD600 of the cell density of the fly ash-fungal bacterial sludge mixture loaded with xanthocillin-producing bacteria is 1.83 multiplied by 108cells/mL。
7. Mixing the fly ash-fungus bacterial sludge mixture obtained in the step 6 with a nutrient solution according to a mass ratio of 1: 1, mixing to obtain grouting liquid.
8. And (3) drying the round cake cement paste test block at 75 ℃ for 24h, cooling the round cake cement paste test block to room temperature in a drying dish, and uniformly coating bacterial sludge on the cross section of the cement paste by using a fine brush. Two parts of the test piece were spliced along the cross section, fixed with a rubber sleeve, and placed in a large beaker (volume 1L or more).
And arranging the peristaltic pump pipe along the cement mortar groove, binding the perforated pipe, and sealing the tail end to ensure that grouting liquid uniformly enters the groove through the perforated pipe and then permeates into cracks. The sealing of unsintered tape is used at the both ends of the groove to prevent the grouting liquid from being deeply arranged at the two sides of the groove.
Grouting liquid is continuously poured for 24 hours, and the grouting speed is 10 mL/h. After a period of pouring, it was found that a large amount of white crystals were formed on the upper, bottom and both sides of the test piece. After the grouting was completed, the broken test pieces were found to be successfully bonded.
The test is carried out by adopting a multifunctional loading machine, the displacement control is adopted, and the loading speed is 0.2 mm/min. Calculating formula Rf is 1.5Ff L/bh according to the breaking strength2(Ff is the load applied to the upper part of the test piece during breaking and has the unit of Newton (N); L is the center distance, namely the span, for supporting the test piece; b is the width of the section of the test piece; and h is the height of the test piece), wherein the span L is 70mm, the section width b is 100mm, the height h is 25mm, the load Ff is 2800, and the flexural strength Rf is calculated to be 4.704 MPa.
Example 2
1. Selecting powdered coal of Lingwu power plantAnd (3) grinding and separating the coarse ash and the coarse ash by using an HLMX superfine vertical mill (Guilin hong Yuan). The measurement shows that the 30 mu m sieve residue of the fly ash is 2.8 percent, and the specific surface area is 7340cm2The loss on ignition is 2.38/g.
2. 1000g of ultrafine fly ash is taken and dried in a drying box, the drying temperature is 150 ℃, and the drying time is 1 h. And (4) drying and cooling to room temperature to obtain the pretreated fly ash.
3. The selected penicillium chrysogenum is purchased from China ocean microbial strain preservation management center, the cell is rod-shaped (length is 4-6 μm), and the spore is circular (diameter is 2.5-3 μm). The culture medium is peptone solution containing inorganic salt, and the components include peptone 10.0g, MgSO4·7H20.5g of O, 0.5g of KCl and 1L of distilled water, and the initial pH value is 6.8. Adjusting pH of the culture medium to 9.0 with sodium hydroxide water solution (mass concentration of 1%), and sterilizing at 150 deg.C for 15min with high pressure steam sterilizing kettle. Inoculating in a sterile environment, and culturing in a shaking incubator (30 ℃, 200rps) for 30h to obtain a bacterial liquid. After standing the fungal suspension for 24h, the OD600 was 8.3X 108cells/mL。
4. The nutrient solution is 1L of CaCl2Mixed solution of urea and Ca2+The concentration is 1mol/L, the CaCl is2And urea in a mass ratio of 1: 1.
5. and (3) mixing the pretreated fly ash obtained in the step (2) with the bacterial liquid obtained in the step (3) according to a mass ratio of 1: 2, carrying out vacuum impregnation treatment for 1h after mixing to obtain a fly ash-fungal bacterial sludge mixture, and measuring that the OD600 of the cell density of the fly ash-fungal bacterial sludge mixture loaded with xanthocillin-producing bacteria is 5.37 multiplied by 108cells/mL。
6. Mixing the fly ash-fungus bacterial sludge mixture obtained in the step 5 with a nutrient solution according to a mass ratio of 1: 1, mixing to obtain grouting liquid.
7. The resulting grout was applied to the patty cement slurry test block of example 1 for the same experimental time and parameter steps. And a multifunctional loading machine is adopted for testing, displacement control is adopted, and the loading speed is 0.2 mm/mim. According to the flexural strength formula in example 1, wherein the span L was 70mm, the section width b was 100mm, the height was 25mm, the load Ff was 2600, and the flexural strength was 4.368 MPa.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method of repairing a fracture comprising the steps of:
A) carrying out high-temperature treatment on the ultrafine fly ash to obtain pretreated fly ash;
B) mixing the bacterial liquid with the pretreated fly ash to immerse the pretreated fly ash into the bacterial liquid, and standing for 0.5-1 h in a vacuum environment to obtain a fly ash-fungus bacterial sludge mixture; the strains contained in the bacterial liquid comprise penicillium chrysogenum;
C) uniformly mixing the fly ash-fungus bacterial sludge mixture with a nutrient solution, and grouting and filling into cracks at the ambient temperature of 20-35 ℃ to realize the repair of the cracks; the nutrient solution is a mixed solution of calcium salt and urea.
2. The repair method according to claim 1, wherein the ultrafine fly ash has a particle size <50 μ ι η;
the specific surface area of the ultrafine fly ash is 6100-8025 cm2/g。
3. The repair method according to claim 1, wherein the high-temperature treatment temperature is 120 to 150 ℃ and the high-temperature treatment time is 1 to 5 hours;
after the high-temperature treatment, the method further comprises the following steps: and cooling to room temperature.
4. The repairing method according to claim 1, wherein the mass ratio of the bacterial liquid to the pretreated fly ash is 2: 1.
5. the repair method according to claim 1, wherein the bacterial strain in the bacterial liquid has a cell density OD600 of 108～109cells/mL。
6. The repair method according to claim 1, wherein the bacterial liquid is prepared by the following method:
inoculating the penicillium chrysogenum into a sterilized culture medium in an aseptic environment, and culturing for 24-36 h in a shaking incubator at 25-35 ℃ to obtain a bacterial liquid; the rotating speed of the shaking incubator is 150-200 rps.
7. The rehabilitation method according to claim 6, wherein the culture medium comprises a carbon source, inorganic salts and water, or the culture medium comprises a nitrogen source, inorganic salts and water;
the carbon source comprises sucrose, lactose, caramel, glucose, starch hydrolysis sugar or saccharification liquid; the DE value of the saccharification liquid is not less than 50%;
the nitrogen source comprises peptone, yeast extract, corn steep liquor, refined cottonseed cake powder, bran, ammonium sulfate or ammonia water;
the inorganic salt comprises one or more of magnesium sulfate, potassium phosphate, sodium sulfate, magnesium nitrate, sodium chloride and sodium nitrate;
the sterilized culture medium is prepared according to the following method:
adjusting the pH value of the culture medium to 7.0-9.0 by adopting NaOH solution, and then sterilizing by using a high-pressure steam sterilization pot;
the sterilization temperature is 120-150 ℃, and the sterilization time is 15-30 min.
8. The repair method of claim 1, wherein the calcium salt comprises CaCl2、Ca(NO3)2And Ca (CH)3COO)2One or more of the above;
in the nutrient solution, Ca2+The concentration is 0.5-1.0 mol/L;
the mass ratio of the fly ash-fungus bacterial sludge mixture to the nutrient solution is 1: 1.
9. repair method according to claim 1, characterized in that the width of the crack does not exceed 5 mm.
10. The repair method according to claim 1, wherein the grouting speed is 10 to 12 mL/h.
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