WO2019189968A1 - Method for injecting microorganism repair liquid for repairing cracks in concrete structure - Google Patents

Abstract

Disclosed is a method for repairing a concrete structure which, by using microorganisms that form calcium carbonate via natural growth in a repair liquid, can repair cracks in concrete, fill the cracks through the self-growth of the microorganisms without a continuous injection of the repair liquid, and resolve the issues of insufficient filling of the cracks in general and long-term falling-out due to curing on a cracked surface of concrete, which are serious issues of an environmentally friendly method of repairing cracks without using an organic repair liquid and of an organic adhesive agent repair technique. The present invention provides the method for repairing a concrete structure by injecting, into a cracked part of the concrete structure, the repair liquid comprising a cultured liquid of at least one microorganism selected from the group consisting of Lysinibacillus sphaericus, Bacillus licheniformis, Pseudomonas putida, and Bacillus subtilis.

Description

Microbial Repair Solution Injection Method for Crack Repair of Concrete Structures

The present invention relates to a method for injecting microbial repair liquid for repairing cracks in concrete structures, and more particularly, to a technique for repairing cracks generated in a concrete structure with microorganisms.

The present invention is derived from a study carried out as part of the 'Construction Technology R & D Project' supported by the Ministry of Land, Infrastructure and Transport (2015 task number: 18SCIP-B103706-04, title: self-healing eco-friendly concrete technology development).

In general, concrete structures are cracked by drying, shrinking and curing after curing, freezing, melting, and stretching of concrete due to external loads.The cracks formed in concrete diffuse into the concrete over time to corrode the steel. Since the strength of the concrete is lowered, it is repaired by injecting filler into the cracked portion.

Conventional repair solution used for repairing cracks in concrete structures is a method of injecting an organic adhesive such as urethane or epoxy resin into the crack width of the concrete.

Injector of compression type is applied by restoring force such as spring or rubber band, and the injector should be continuously installed until the injection material is completely cured. This is difficult to continuously inject due to the curing of the organic adhesive in the injector, and may cause cracking if the injection pressure is not maintained below 4 kg / m ² . In addition, when the crack is deeply developed, the overall crack repair may be difficult due to the hardening of the organic adhesive at the crack inlet. In particular, the organic adhesive has a difference in thermal expansion coefficient of 5 to 10 times or more compared with concrete, and it is pointed out that the effect of actual crack repair is insignificant due to peeling from concrete in a long-term behavior.

In addition, in the case where cracks occur due to external environment or concrete expansion after curing of concrete structures, especially micro cracks are not easy to repair cracks and cause gradual crack diffusion of concrete, The filler can be applied to the minute cracks that are difficult to fill by using a powder encapsulant using a conventional epoxy.

As microorganisms that can fill the internal cracks of concrete structures, sporosalina or S. pasteurii bacteria or B. pasteurii bacteria are used. The microorganisms react with cement to extract nitrogen from urea. In the process, carbon dioxide and ammonia are generated as by-products, which react with water to form calcite (calcium carbonate), which is then filled in the cracks in the concrete.

Korean Patent Publication No. 2015-0111528 discloses a Cinibacillus sp. Aerica WJ-8 strain that is used in soil environment industry and construction industry by applying to concrete and enabling environmentally friendly crack repair and ground reinforcement, but Bacillus licheniformis, It is not described for Pseudomonas putida .

Korean Unexamined Patent Publication No. 2013-0078211 discloses cement additives for improving durability and crack repair of cement pastes or concretes containing Paenibacillus polymyxa E681 KCTC3858, but do not describe Bacillus licheniformis, Pseudomonas putida . .

The present invention is to provide a repair solution injection method that can be used to repair the concrete cracks using a specific microbial culture medium as a repair solution, and to exert a crack filling effect through the self-growth of microorganisms without continuous injection of the repair solution.

In order to solve the above problems, the present invention is Lysinibacillus sphaericus, Bacillus licheniformis, Pseudomonas putida and Provided is a method for repairing a concrete structure by injecting a repair solution containing at least one microbial culture medium selected from the group consisting of Bacillus subtilis to the crack of the concrete structure.

In addition, the medium composition for inoculation and culture of the microorganism is 4-6 g of peptic digest of animal tissue, 4-6 g of sodium chloride, and beef extract based on 1 l of distilled water. ) 1 to 2g and yeast extract (Yeast extract) provides a method comprising a.

In addition, the composition of the medium for the formation of calcium carbonate medium is based on agar (Agar) 20g urea (Urea) 18 ~ 22g, sodium bicarbonate (NaHCO ₃ ) 2 ~ 3g, ammonium chloride (NH ₄ Cl) 8 ~ 12g, nutrition It provides a method comprising the medium (Nutrient broth) 2 ~ 4g and calcium chloride (CaCl ₂ ) 20 ~ 40ml.

In addition, the repair solution is a natural ocher containing 35 ~ 45wt% silicon dioxide (SiO ₂ ), 5 ~ 10wt% iron hydroxide (Fe ₂ O ₃ ) and 28 ~ 38wt% aluminum oxide (AL ₂ O ₃ ) 100 weight of the microbial culture It provides a method characterized in that 20 to 40 parts by weight based on parts.

According to the present invention, by using the microorganisms that form calcium carbonate through natural growth as a repair solution, it is possible to repair the concrete cracks, and to provide a crack filling effect through self-growth of microorganisms without continuous injection of the repair solution.

In addition, the present invention can provide an environmentally friendly crack repair method excluding the use of an organic repair solution.

In addition, the present invention can solve the problem of the lack of overall crack filling and long-term dropout by hardening in the concrete crack surface, which is a serious problem of the organic adhesive repair technology.

1 is a view showing a concrete crack repair process by a repair solution containing microorganisms.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, throughout the specification, when a part is said to "include" a certain component, it means that unless otherwise stated, it may further include other components other than the other components.

Hereinafter, the components of the repair solution according to the present invention will be described in detail.

Isolation and Screening of Calcium Carbonate Forming Strains

Continuous growth is possible in the alkaline environment of concrete, and the microorganisms that form calcium carbonate (CaCO ₃ ) through metabolic activity were selected (see Table 1 below). These microorganisms absorb various ions such as Ca ⁺ necessary for growth from the surrounding environment and form calcium carbonate (CaCO ₃ ) around the cell membrane through metabolic activity.

turn	Species (Accession Number)
One	Lysinibacillus sphaericus (JCM 2502)
2	Bacillus licheniformis (KCTC 1753)
3	Pseudomonas putida (JCM 13063)
4	Bacillus subtilis (JCM 1465)

In the present invention, the microorganisms included in the repair solution of the concrete structure are Lysinibacillus sphaericus, Bacillus licheniformis, Pseudomonas putida and Pseudomonas putida. One or more microorganisms selected from the group consisting of Bacillus subtilis, used to generate calcium carbonate by reacting with the cement component of concrete, hydrolysis of minerals and urease (urease) to the microorganisms It can increase the calcium ion by the addition of enzymes to promote the freezing reaction of calcium carbonate.

The Lysinibacillus sphaericus is commonly found in soil. It can form resistant spores that can withstand high temperatures, chemicals and ultraviolet radiation and can survive for a long time.

Lysinibacillus sphaericus can be isolated and selected by known methods. For example, the collected soil samples are diluted 10-fold in buffer solution (0.1M phosphate buffer pH 7.4) and then incubated at 28 ° C. and 200 rpm for one day. After incubation, the mixture was thoroughly mixed using a vibrator, diluted 10-fold in a buffer solution, and then 100 μl was taken. BPU agar medium containing 100 μg / mL of cycloheximide (Beef extract: 3g / L, Peptone: 5 g / L, Urea: 20 g / L, PH: 8.3), and dispersed and incubated at 28 ° C. and 200 rpm for one day.

The microorganisms were incubated at 28 ° C. and 200 rpm for one day in a BPU liquid medium, and then treated with a 0.2 μm syringe filter to remove the microorganisms. Then, 100 μL of CaCl ₂ (100 mM) aqueous solution was added to 1 mL of the filtrate. Reselect the microorganism causing the precipitation reaction and store at -70 ° C as 25% glycerol stock.

Among the strains showing precipitation reaction, the strains showing the highest activity were finally selected through specific urease actvity, and the finally isolated strains were molecularly identified through 16S rDNA gene sequence (Patent No. 10-1489164). Reference).

The Bacillus licheniformis is a bacterium generally present in soil. It is also found in bird feathers (especially breast and dorsal feathers), and is a particular bacteria present in poultry. Bacillus rickeniformis is a Gram-positive bacterium and aerobic bacteria. The optimum growth temperature is 50 ° C., but may be present at temperatures above. Under unfavorable environmental conditions of growth, they exist in the form of spores and grow rapidly when they are favorable.

The Bacillus licheniformis can be isolated and selected by a known method. For example, 20 g of by-product fertilizer is mixed with 100 ml of sterile saline solution and allowed to stand for 1 hour, and then the supernatant from which the solids are removed is placed in a YM flat medium (10 g of glucose, 5 g of peptone) in which spores of the red pepper pathogen are coated in advance. , 3 g of malt extract, 3 g of yeast extract, agar 20 g / liter) and stir mixed incubate for 3 days in an incubator. By measuring the diameter of the formed growth inhibition zone (inhibition zone, diameter) up to mm, the microorganisms that are considered to have excellent antifungal activity are selected and used, and finally, the microorganisms that exhibit the highest antagonistic ability are selected. See 2002-0064691).

Pseudomonas putida is a species commonly inhabiting soil, water or plants. It is a gram-negative aerobic strain inhabiting soil, and it is reported that it is applicable to the bioremediation of PHA (polyhydroxyalkanoate) and xenobiotic as a nutrient-derived buffet organic material (Worsey, MJ et al. , Journal of Bacteriology, 124 (1): 7-13, 1975; Simon, MJ et al., Gene, 127 (1): 31-37, 1993; Annadurai, G. et al., Bioprocess Engineering, 22 (6): 493-501, 2000; Monteiro, AA et al., Biochemical Engineering Journal, 6 (1): 45-49, 2000; Nelson, KE et al., Environmental microbiology, 4 (12): 799-808 , 2002). In addition, it decomposes lignin constituting lignocellulosic acid (Ahmad, M. et al., Molecular Biosystems, 6 (5): 815-821, 2010), and decomposes the coal in a medium containing low grade coal. Biodegradation has been reported (Machnikowska, H. et al., Fuel Processing Technology, 77: 17-23. 2002).

The Pseudomonas putida can be separated from soil or sludge and can decompose aromatic contaminants, especially chlorinated aromatic compounds (see Publication No. 10-2017-0031960).

Bacillus subtilis ( Bacillus subtilis) is a gram-positive bacillus that is widely distributed in nature such as soil, hay, dust, and bacteria, commonly called "battery bacteria". Endogenous spores are formed in 2-3 micrometers in length and aerobic. Spores are resistant to heat, radiation and chemicals and remain dormant for a long time. Early transformation was found, and because it can grow on simple media, it has been widely used for researches on molecular genetics and recombinant DNA experiments. Bacillus subtilis ( Bacillus subtilis) is a production microorganism such as amylase and protease of extracellular enzymes are important in applied microbiology, recently attracting attention as a material of genetic engineering.

The Bacillus subtilis ( Bacillus subtilis) can be isolated from the soil, etc., the strain can be identified using the nucleotide sequence of the 16s rRNA of the bacteria (see Patent Publication No. 10-2014-0028777).

Medium composition for microbial culture

Nutrient supply is necessary to help the microorganisms continue to grow. A medium composition technique was developed for the culture of calcium carbonate (CaCO ₃ ) forming microorganisms (see Table 2 below). Inoculate the calcium carbonate-forming microorganisms in the "Nutrient broth" medium, and incubate for 7 days in an incubator at 30-37 ℃. Add the medium "Calcium carbonate precipitation media" for forming calcium carbonate to the culture medium.

Media components for bacterial inoculation and culture
Name	ingredient
Nutrient broth (pH 7.4 ± 0.2 at 25 ℃)	Peptic digest of animal tissue	5.0 g
	Sodium chloride	5.0 g
	Beef extract	1.5 g
	Yeast extract	1.5 g
	Distilled water	1 L
Medium component for calcium carbonate formation in bacteria (input after completion of bacterial culture)
Name	ingredient
Calcium carbonate precipitation media	Urea	20 g
	NaHCO 3	2.12 g
	NH 4 Cl	10 g
	Nutrient broth	3 g
	CaCl 2	30 mL
	Agar	20 g

The medium (“Nutrient broth”) composition for inoculation and cultivation of the microorganism is 4-6 g of peptic digest of animal tissue, 4-6 g of sodium chloride, based on 1 L of distilled water, Meat extract (Beef extract) may include 1-2g and yeast extract (Yeast extract) 1-2g.

The meat extract (Beef extract) is used as a medium component (培 地 成分) for bacterial culture (細菌 培養 用). The exudates of beef or horse meat, or concentrates thereof, contain abundant nutrients such as amino acids, peptides, organic acids, phosphoric acid and vitamins.

The yeast extract (Yeast extract) is composed of the water-soluble components of amino acids, peptides, carbohydrates and salts of the yeast cells. Polypeptide bonds are hydrolyzed by the addition of enzymes or food enzymes originally present in the edible yeast, and salts can be added during the manufacturing process. Natural additives in liquid, powder, granule or paste form.

The composition of the medium for forming calcium carbonate (“Calcium carbonate precipitation media”) is based on 20 g of agar (Agar), 18 to 22 g of urea, 2 to 3 g of sodium bicarbonate (NaHCO ₃ ), and ammonium chloride (NH _4). Cl) may contain 8 to 12g, 2 to 4g of nutrient broth (Nutrient broth) and 20 to 40ml of calcium chloride (CaCl ₂ ).

The agar extracts seaweed from hot water, freezes and melts the solidified by concentrating and cooling the extract, and then drying it. It is white, transparent and glossy, and does not dissolve in cold water. Swell.

The urea (Urea) is also called urea, carbamide (Carbamide), Diaminomethanal (Diaminomethanal). Chemical formula CO (NH ₂ ) ₂ . It is a colorless or odorless material that produces columnar crystals. It has a molecular weight of 60.047, a melting point of 132.7 ° C (1 atm) and a specific gravity of 1.335. It is a highly polar substance that is soluble in water and alcohol but insoluble in ether

The sodium bicarbonate (NaHCO ₃ ) is a white powder at room temperature, slightly bitter taste. And if excessive, it will corrode the skin. As a medicine, it is used as an antacid against excess acid. It is also used in food and beauty products such as coffee. When heated with white monoclinic crystals, carbon dioxide and water were generated and changed to sodium carbonate anhydride.

Ammonium chloride (NH ₄ Cl) is a salt of ammonia, which is a clear, white, water-soluble crystal. It naturally exists in volcanic and hot spring areas, and industrially, it is produced in large quantities by salt and ammonia soda method. It can obtain by neutralization of ammonia and hydrochloric acid, metathesis of ammonium sulfide, and a salt.

The nutrition broth (Nutrient broth) is a kind of bacterial medium that generally uses the extract of fish or fish meat. It is mainly used for bacterial culture of by-product organic nutrition. Agar is often added to make it a solid medium, which is called agar medium.

The present invention can promote the continuous growth activity of microorganisms by varying the composition of the medium for inoculation and culture of the microorganisms and the formation of calcium carbonate, so that the effect of crack filling through the self-growth of microorganisms can be realized without continuous injection of a maintenance solution. .

Calcium carbonate forming ability

The selected Lysinibacillus sphaericus, Bacillus licheniformis, Pseudomonas putida and In order to confirm that Bacillus subtilis forms calcium carbonate, each of the microorganisms is inoculated into the "Nutrient broth" medium and incubated for 7 days in an incubator at 30 to 37 ° C. "Calcium carbonate precipitation media" was added to the culture-completed medium and filtered through a 0.2 μm syringe filter to obtain a filtrate from which microorganisms were completely removed. 500 μl of the filtrate and 500 μl of filtered sterilized aqueous 350mM CaCl ₂ solution were confirmed to form a white precipitate, followed by centrifugation (16179 xg, 5 min) to obtain a precipitate. The precipitate was dried at 50 ° C. for 24 hours and then measured at 2θ intervals at 10 ° -90 ° using an X-ray diffractometer (DMAX-2500, Rigaku, Tokyo, Japan).

In addition, in order to quantitatively measure calcium carbonate, culture medium was collected from 0 hours to 24 hours in units of 3 hours, and then culture medium was collected at 48, 72, and 96 hours thereafter. Thereafter, the collected culture solution was filtered through a 0.2 μm syringe filter to obtain a filtrate from which microorganisms were completely removed. 500 µl of the filtrate was added to 500 µl of filtered sterilized aqueous 350 mM CaCl ₂ solution to induce precipitation, and the precipitate was obtained by centrifugation (16179 xg, 5 min). The precipitate obtained was dried at 50 ° C. for 24 hours and weighed.

As a result, qualitative confirmation of calcium carbonate through X-ray diffraction analysis showed that calcium carbonate and its isomer were formed in trace amount of batterite. In addition, as a result of quantitatively checking calcium carbonate, it was not produced at the beginning of culture, but after 6 hours of culture, 2.3 mg / mL of calcium carbonate was produced, and after 48 hours, up to 10.0 mg / mL of calcium carbonate was formed. Could know.

On the other hand, by adding a natural ocher in the range of 2,800 ~ 3,500 cm ² / g powder to the water can be secured viscosity so that the water does not flow down. The addition rate of natural loess may be included 20 to 40 parts by mass relative to the repair solution.

In addition, the natural ocher contains 35 to 45 wt% of silicon dioxide (SiO ₂ ), 5 to 10 wt% of iron hydroxide (Fe ₂ O ₃ ), and aluminum oxide (AL ₂ O ₃ ), 28 to 38 wt% to ensure viscosity of the repair solution. Preference is given to (see Table 3 below).

Ingredient Content (%, weight)
SiO 2	Fe 2 O 3	Al 2 O 3	CaO	MgO	K 2 O	Na 2 O
40.0	7.79	32.9	0.39	1.54	0.76	1.73

Injection method of repair liquid

In the method of injecting the microbial repair solution, the repair solution injector is fixed and mounted on the crack in the concrete. The repair fluid is continuously and automatically introduced into the crack by the tension of the rubber band. The injector lasts 5-10 days. That is, the microorganisms injected into the concrete cracks form calcium carbonate through continuous self-growth and repair the cracks.

According to the method for repairing the concrete structure as described above, by using the microorganisms that form calcium carbonate through natural growth as a repair liquid, it is possible to repair the concrete cracks, and provide a crack filling effect through the self-growth of microorganisms without continuous injection of the repair liquid. have. In another aspect, the present invention can provide an environmentally friendly crack repair method excluding the use of an organic repair solution. In addition, the present invention can solve the problem of the lack of overall crack filling and long-term dropout by hardening in the concrete crack surface, which is a serious problem of the organic adhesive repair technology.

Preferred embodiments of the present invention have been described in detail above with reference to the drawings. The description of the present invention is for illustrative purposes, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is shown by the claims below rather than the description of the invention, and all changes or modifications derived from the meaning, scope and equivalent concept of the claims are to be included in the scope of the present invention. Should be.

Claims (4)

1. Lysinibacillus sphaericus, Bacillus licheniformis, Pseudomonas putida, and A method of repairing a concrete structure by injecting a repair solution containing at least one microbial culture medium selected from the group consisting of Bacillus subtilis into the crack of the concrete structure.
2. The method of claim 1,

   The medium composition for inoculation and culture of the microorganism is 4-6 g of peptic digest of animal tissue, 4-6 g of sodium chloride, and beef extract based on 1 l of distilled water. 1 to 2 g and yeast extract (Yeast extract) method comprising a 1 to 2 g.
3. The method of claim 1,

   Medium composition for calcium carbonate formation of the microorganism is 18g to 22g of urea (Urea), 2 ~ 3g of sodium bicarbonate (NaHCO ₃ ), 8 ~ 12g of ammonium chloride (NH ₄ Cl), based on 20g of agar (Agar) (Nutrient broth) 2 to 4g and calcium chloride (CaCl ₂ ) 20 to 40mL method comprising the.
4. The method of claim 1,

   The repair solution is 100 parts by weight of natural microorganisms containing 35 to 45 wt% of silicon dioxide (SiO ₂ ), 5 to 10 wt% of iron hydroxide (Fe ₂ O ₃ ) and 28 to 38 wt% of aluminum oxide (AL ₂ O ₃ ). 20 to 40 parts by weight with respect to the method characterized in that the addition.

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