WO2018110739A1 - Development of bacteria slime-based concrete protective coating material - Google Patents

Abstract

The present invention provides, as a bacteria slime-based coating material using bacteria capable of forming slime, a coating material comprising an adsorbent on which slime-forming bacteria are adsorbed, and a binder. According to the present invention, an optimal slime-forming bacteria and optimal slime-forming conditions that take concrete chemical resistance into consideration; an optimal adsorption method for a viable autotrophic environment for bacteria, rather than simple injection, during the blending of an existing concrete; a technique for utilizing an optimal binder having a pH of about 8-10 in consideration of bacteria growth environment; and a method which is economical compared to a prior art technique of injecting bacteria and enables easy and substantial adsorption of a large quantity of bacteria may be provided. Also, a novel coating material that enhances concrete chemical resistance and durability and takes into consideration the mechanisms involved in the chemical erosion of a concrete sewer and the mechanisms involved in the resistance of slime-forming bacteria to sulfuric acid may be provided.

Description

Development of bacterial slime based concrete protective coating

The present invention relates to concrete protective material technology, and more particularly to a bacterial slime-based concrete protective coating.

The present invention is derived from the research carried out by the grant support of the Ministry of Land, Infrastructure and Transport construction technology research project.

[Project No .: 16SCIP-B103706-02, Project Title: Self-healing Eco-friendly Concrete Technology Development]

Concrete exposed to corrosive environments such as sewage, manure, and livestock wastewater has problems of deterioration in usability and safety due to various deterioration and chemical erosion, which has a durability life of less than 20-30 years (Kim, Jong-Pil, 2005). For this reason, developed countries have defined relevant standards and codes for the durability design of concrete and have established and applied systematic systems (ACI 318-11, 2011; ACI 201.2R-08, 2008; BS EN 7543, 2003). In the case of ACI 318-11 (2011) in the US, the durability design of concrete was treated as part of the structural design. ACI 201.2R-08 (2008) showed that the concrete was freeze-thawed, chemical erosion, abrasion and alkali aggregate reaction. Damage mechanisms for the cases affected by the papers and the countermeasures required accordingly are presented. BS EN 7543 (2003) provides a general process for the guidance, target endurance and design endurance necessary for predicting the durability of structures. On the other hand, ISO (2004), an international standardization organization, is conducting research on repair and reinforcement due to deterioration of concrete due to chemical erosion, centering on TC71 / SC7. In Korea, the 'Concrete Standard Specification-Durability' was enacted in 2004 under the supervision of the Ministry of Construction and Transportation and the Korea Concrete Institute. In line with various policy and social requirements for improving the endurance, the construction industry is expected to increase the applicability of coating materials in terms of maintenance for concrete exposed to corrosive environments (Kim, Seong-su, 2013).

The use of concrete coatings is rapidly increasing due to seawater salts and chemical erosion such as sulfuric acid in the soil. It is known that the deterioration of concrete durability by sulphate is larger than other chemical erosion factors (Al-Amoudi, 2002). Therefore, organic coatings such as epoxy, urethane, and acrylic having strong water resistance are generally used for controlling corrosion of concrete (Chun Byung Sik, 2004). However, the coating film formed on the adhesive surface of the concrete and the coating material is difficult to evaporate the moisture present in the concrete to the outside, causing the coating film to drop out. In addition, during the winter construction, the moisture formed at the interface of the coating film is frozen and an expansion pressure is generated at the interface (Kim, Seong-su, 2003). This results in concrete cracking and deformation, which significantly reduces the efficiency of increasing the service life. In addition, organic coatings contain large amounts of environmental pollution and harmful substances, and strictly regulate the raw materials and manufacturing processes used worldwide. Accordingly, eco-friendly coating materials that do not contain heavy metals and volatile organic compounds (VOCs) have been developed and commercialized in developed countries such as Europe (Bazant et al., 1994). On the other hand, more than 60% of the domestic paint (coating) industry relies on foreign technology (Korea Institute of Science and Technology Information). Therefore, domestic technology for the development of new eco-friendly coating material that can cope with technical and environmental requirements is necessary. In addition, in order to escape the low-tech image in the domestic construction industry, a new concept of construction materials technology strategy incorporating advanced technologies (Bio / Nano / Eco) is required.

Recently, researches on new technologies such as surface coating, crack repair, and self-healing concrete using microbial calcium carbonate formation to maintain target performance and durability life of concrete structures have been conducted (Achal, 2009; DeMuynck, 2008; Kim Hwa-joong, 2010). However, microbial concrete is the source technology development stage, and most of the qualitative evaluation through image analysis. In addition, most of the concrete research using microorganisms focuses on crack treatment using microorganisms in the Basiler system, and there is no research on coating materials. In particular, the slime film due to microorganisms can be expected to improve the corrosion resistance of concrete structures while solving the disadvantages of existing coating materials, but the verification studies are still insufficient. Most studies have used biomineralization of microorganisms. The research focused on the study of crack healing, durability improvement, self-healing concrete, and the application of microorganisms capable of water purification.

However, in the existing research, research on self-healing concrete and water purification concrete that can maintain the target performance and lifespan is mainly conducted for eco-friendly concrete utilizing bacteria, There are few domestic and foreign patents and similar studies.

The present invention proposes a coating material using slime (glyco callis membrane) bacteria as a basic technology for fusing bacteria and concrete technology, and based on this, to evaluate the effect of bacterial slime-based coating on the sulfuric acid behavior of concrete. To this end, an object of the present invention is to select an optimal bacterium capable of slime formation, to cultivate bacteria for slime formation and to present an optimal medium condition, and to present an optimal adsorbent for immobilization of slime-formed bacteria. To establish a bacterial slime-based coating material technology.

In order to solve the above problems, the present invention provides a coating material comprising an adsorbent and a binder adsorbed slime forming bacteria.

The present invention for solving the another problem, the step of culturing the slime forming bacteria to form a slime; Adsorbing the slime-formed bacteria using an adsorbent to fix the slime-formed bacteria; And mixing the bacteria adsorbed material with the binder.

According to the present invention, it is possible to provide optimum slime forming bacteria and optimal slime forming conditions in consideration of concrete chemical resistance.

In addition, it is possible to provide an optimal adsorption method for bacterial autotrophic survival environment, rather than simple input when mixing existing concrete.

In addition, it can provide the utilization technology of the optimum binder of pH 8-10 level considering the bacterial growth environment.

In addition, it is possible to provide a method that is economical compared to the prior art for the introduction of bacteria and facilitates substantial adsorption of a large amount of bacteria.

In addition, it is possible to provide a coating material technology to improve the concrete chemical resistance and durability of the new concept considering the mechanism of chemical erosion of concrete sewer pipe and the sulfuric acid resistance mechanism of slime forming bacteria.

1 is Rhodobacter Rhodobacter capsulatus), Rhodobacter Blind stitch kusu (Rhodobacter blasticus), Rhodobacter sphaeroides (Rhodobacter sphaeroides ), Rhodopseudomonas photo showing the formation of a slime (glycocalyx) membrane around cells in palustris ) and Rubrivivax gelatinosus ,

2 is a schematic diagram showing a performance degradation mechanism of concrete by sulfuric acid,

Figure 3 is a schematic diagram showing the bacteria-based coating mechanism of the slime and SEM analysis of the coating microstructure,

Figure 4 is a schematic diagram showing an exemplary adsorption pad (a) and the culture vessel (b) in which the adsorption pad is immersed in the embodiment of the present invention,

Figure 5 is a photograph showing the changed state after 7 days of cultured bacteria in the embodiment of the present invention,

Figure 6 is a micrograph of the shape and structure of the slime membrane of Rhodobacter capsulatus cultured in an embodiment of the present invention,

Figure 7 is a photograph showing the freeze-dried slime membrane according to each medium in the embodiment of the present invention,

Figure 8 is also in connection with an embodiment of the present invention bakteo la capsule tooth (Rhodobacter capsulatus ) and graph showing slime production,

9 is bakteo also in the embodiment of the present invention the capsule la tooth (Rhodobacter capsulatus ) graph showing the slime composition of

10 is a photograph showing the surface structure of a high absorbent polymer in an embodiment of the present invention,

Figure 11 is a photograph showing the surface structure of a highly porous resin in an embodiment of the present invention,

12 is a photograph showing the surface structure of the expanded vermiculite in the embodiment of the present invention,

Figure 13 is a photograph showing the surface structure of pearlite in the embodiment of the present invention,

14 and 15 are photographs showing the observation results of the surface texture of each adsorbent for Rhodobacter capsulatus in the embodiment of the present invention,

16 is a graph showing the results of X-ray diffraction analysis (XRD) of the loess-based binder in an embodiment of the present invention,

17 is a schematic diagram and photographs illustrating a method for measuring sulfuric acid penetration depth of concrete immersed in a 5% sulfuric acid solution in Experimental Example 1 of the present invention;

18 and 19 are graphs showing the X-ray diffraction analysis (XRD) pattern according to the presence of bacteria in the coating material and the type of medium in Experimental Example 1 of the present invention,

20 and 21 are photographs showing the internal microstructure according to the presence of bacteria in the coating material and the type of medium in Experimental Example 1 of the present invention,

22 and 23 are photographs showing the appearance of the test body for each immersion days according to the sulfuric acid immersion of the first group in Experimental Example 1 of the present invention,

24 is a photograph showing the results of observing the sulfuric acid penetration depth of the first group in Experimental Example 1 of the present invention,

26 and 27 are graphs showing the results of analyzing the main diffraction peaks of the reaction product of the sample taken from the first group of concrete surface in Experimental Example 1 of the present invention,

27 to 29 are photographs showing the structure and chemical member analysis results of the samples taken from the first group of concrete surface in Experimental Example 1 of the present invention,

30 is a graph showing the weight change of sulfuric acid immersion days of the first group in Experimental Example 1 of the present invention,

31 is a graph showing the compressive strength reduction ratio for each immersion days according to the sulfuric acid immersion of the first group in Experimental Example 1 of the present invention,

32 and 33 are graphs showing the ratios of decreasing the coefficient of dynamic modulus and the ratio of decreasing the coefficient of elastic modulus of the central portion of the test specimen at 28 days of immersion of sulfuric acid in the first group in Experimental Example 1 of the present invention, respectively;

34 and 35 are photographs showing the appearance of the test body for each immersion days according to the sulfuric acid immersion of the second group in Experimental Example 1 of the present invention,

36 is a photograph showing the results of observing the sulfuric acid penetration depth of the second group in Experimental Example 1 of the present invention,

37 and 38 are graphs showing the results of analyzing the main diffraction peaks of the reaction product of the sample taken from the concrete surface of the second group in Experimental Example 1 of the present invention,

39 and 40 are photographs showing the structure and chemical member analysis results of the samples taken from the concrete surface of the second group in Experimental Example 1 of the present invention,

41 is a graph showing a weight change of sulfuric acid immersion days of the second group in Experimental Example 1 of the present invention;

42 is a graph showing a compressive strength reduction ratio by immersion days according to sulfuric acid immersion of the second group in Experimental Example 1 of the present invention;

43 and 44 are graphs each showing the ratio of decrease in dynamic modulus of elasticity at the center of the test body and the ratio of decrease in dynamic modulus of the surface at 28 days of immersion of sulfuric acid in the second group in Experimental Example 1 of the present invention;

45 and 46 are photographs showing the appearance of the test body for each immersion day according to the sulfuric acid immersion of the third group in Experimental Example 1 of the present invention,

47 is a photograph showing the results of observing the depth of sulfuric acid penetration of the third group in Experimental Example 1 of the present invention,

48 and 49 are graphs showing the results of analyzing the main diffraction peaks of the reaction product of the sample taken from the third group of concrete surface in Experimental Example 1 of the present invention,

50 and 51 are photographs showing the structure and chemical member analysis results of the samples taken from the third group of concrete surface in Experimental Example 1 of the present invention,

52 is a graph showing a weight change of sulfuric acid immersion days of the third group in Experimental Example 1 of the present invention;

53 is a graph showing a compressive strength reduction ratio for each immersion day according to sulfuric acid immersion of the third group in Experimental Example 1 of the present invention;

54 and 55 are graphs showing the dynamic modulus reduction ratio and the dynamic modulus reduction ratio of the central portion of the test specimen at 28 days of immersion of sulfuric acid of the third group in Experimental Example 1 of the present invention, respectively;

56 is a photograph showing the appearance of each specimen by immersion days according to sulfuric acid immersion in comparison with the conventional technology in Experimental Example 1 of the present invention;

57 is a graph showing the weight change of sulfuric acid immersion days in comparison with the existing technology in Experimental Example 1 of the present invention,

58 is a graph showing a compressive strength reduction ratio for each immersion day according to sulfuric acid immersion in comparison with the existing technology in Experimental Example 1 of the present invention;

59 and 60 are graphs showing the dynamic modulus reduction ratio of the central portion and the dynamic modulus reduction ratio of the central portion of the test body at 28 days of sulfuric acid immersion in comparison with the conventional technology in Experimental Example 1 of the present invention, respectively;

Figure 61 is a photograph showing the appearance of the specimens by immersion days according to the sulfuric acid immersion in Experimental Example 2 of the present invention,

62 is a graph showing a change in compressive strength of a test specimen according to immersion age in Experimental Example 2 of the present invention;

63 is a graph showing the mass change of the test specimen according to the immersion age in Experimental Example 2 of the present invention,

64 is a photograph showing a microstructure analysis result for evaluation of adsorption of bacteria after 28 days of immersion in a 5% sulfuric acid aqueous solution in Experimental Example 2 of the present invention.

65 is a graph showing a change in mass of a test specimen according to an immersion age in Experimental Example 3 of the present invention;

66 is a graph showing a change in compressive strength of a test specimen according to immersion age in Experimental Example 3 of the present invention;

67 is a photograph showing the results of confirming the formation of a colony by re-inoculating (passaging) a sample of the surface of the coating material collected after 7 days of dipping age in Experimental Example 4 of the present invention,

68 is a graph showing the compressive strength and pH measurement results of the test body according to the magnesia-phosphate complex composition in Experimental Example 4 of the present invention;

69 is a graph showing the compressive strength and pH measurement results according to the type of phosphate in Experimental Example 4 of the present invention.

Hereinafter, the present invention will be described in detail through examples. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the configuration of the embodiments described herein is only one of the most preferred embodiments of the present invention and does not represent all of the technical idea of the present invention, various equivalents and modifications that can replace them at the time of the present application It should be understood that there may be

The present invention discloses a coating material comprising an adsorbent and a binder for adsorbing slime forming bacteria, the coating material comprising the steps of culturing the slime forming bacteria to form a slime; Adsorbing the slime-formed bacteria using an adsorbent to fix the slime-formed bacteria; And mixing the bacteria adsorbed material with the binder.

If possible this slime forming bacteria as possible utilizing bacteria in the present invention, not particularly limited, for example, Rhodobacter la capsule tooth (Rhodobacter capsulatus), Rhodobacter Blind stitch kusu (Rhodobacter blasticus , Rhodobacter sphaeroides , Rhodopseudomonas palustris , Rubrivivax gelatinosus ), purple sulfur bacteria, green sulfur bacteria, Rhodoseudomonas palustris , Bacillus thuringiensis , Bacillus subtilis , etc. May be used). Rhodobacter capsulatus is able to grow under aerobic and anaerobic conditions. Jeonghwahwa (2010) used Rhodobacter capsulatus to remove nitrogen and phosphorus from sewage and wastewater treatment facilities.

In Figure 1 of the bacteria Rhodobacter capsulatus ( Rhodobacter capsulatus ), Rhodobacter blasticus ( Rhodobacter blasticus ), Rhodobacter sphaeroides , Rhodopseudomonas palustris and Rubrivivax gelatinosus ) shows the formation of a slime (glycocalyx) membrane around the cell.

The coating material according to the present invention can be used to prevent chemical erosion of the surface of the concrete structure, hereinafter will be described as an example of the degradation mechanism of the concrete by sulfuric acid and the slime bacteria-based coating mechanism.

Figure 2 is a schematic diagram showing the performance degradation mechanism of concrete by sulfuric acid.

2, the corrosion stage of the concrete exposed to the sulfuric acid environment can be largely divided into three stages. In the first step, sulfate ions (SO ₄ ^2- ) are formed as hydrogen sulfide (H ₂ S) by sulfur reduction bacteria (SRB) among organic compounds contained in the waste water. To sulfuric acid (H ₂ SO ₄ ) (see Scheme 1 below). In the second step, the produced sulfuric acid reacts with calcium hydroxide (Ca (OH) ₂ ), which is a cement component, to produce dihydrate gypsum (CaSO ₄ · 2H ₂ O) (see Scheme 2 below). In step 3, the resulting dihydrate gypsum and tricalcium aluminate (C3A) react to produce ettringite (see Scheme 3 below). As such, Ettringite and Gypsum produced by reaction with cement hydrate generate expansion and softening of concrete and breakage and cracking of tissue structure.

Scheme 1

H ₂ S + ₂ O ₂ → H ₂ SO ₄

Scheme 2

Ca (OH) ₂ + H ₂ SO ₄ → CaSO ₄ 2H ₂ O

Scheme 3

_{CaSO 4 + 3CaO 3 Al 2 O} 3 + 26H 2 O → CaO 3 Al 2 O 3 · 3CaSO 4 · 32H 2 O

3 is a schematic diagram showing the bacteria-based coating mechanism of the slime and SEM analysis of the coating microstructure.

Referring to Figure 3, slime forming bacteria ( Rhodobater capsulatus) forms a slime (Glycocalyx) around the cell via the metabolic activity, which causes the volume expansion of the ion exchange surface, and shows the colonies (Colony) and form clusters of micro-organisms. The nature of these bacteria attracts various ions (elements such as silicon, magnesium and calcium dissolved in water) including calcium from the surrounding environment. The silica component (SiO ₂ ) and the small amount of calcium carbonate (CaCO ₃ ) formed inside the coating material are minerals synthesized by combining inorganic and organic materials, and the precipitation reaction of the biochemical concept accompanied by the microbial metabolism action, not the precipitation of the pure chemical concept. (Kim, 2009). The slime film thus formed makes the internal structure of the coating material dense and low permeability, thereby preventing harmful substances such as sulfate from invading from the outside. Furthermore, even if sulfate penetrates into the coating material, organic-inorganic minerals such as silica (SiO ₂ ) formed inside the coating material fill the internal pores with fine particles, and as the age increases, the internal structure becomes dense and durable due to the pozzolanic reaction. Effective in promoting Therefore, the species specificity of the bacteria and the medium (enzyme) determine the characteristics of the mineral crystal, and it is judged to give the species specificity and the medium (enzyme) effect on the durability and density of the coating material.

Meanwhile, in the case of purple sulfur bacteria and green sulfur bacteria, hydrogen sulfide is used as an electron donor to decompose hydrogen sulfide under anaerobic or through anaerobic conditions, which is more advantageously employed. Can be, Rhodobater capsulatus ) is a bacterium used to remove nitrogen and phosphorus from sewage treatment plants, which can be applied to slime bacteria-based coatings to self-cleaning.

The present invention proposes an optimal medium composition and culture conditions having excellent efficiency in inoculation culture based on the characteristics of each bacterium based on the results of research on a special medium composition to create an optimal culture environment of the bacteria.

Specifically, the Rhodobacter capsuleratus ( Rhodobacter capsulatus ), Rhodobacter blasticus , Rhodobacter sphaeroides , Rhodopseudomonas palustris ), Rubrivivax gelatinosus ), purple sulfur bacteria and green sulfur bacteria are 0.1 ~ 5g yeast extract, 1 ~ 50g of disodium succinate hexahydrate, ethanol anhydride (Absolute ethanol) 0.1 ~ 5㎖, iron citrate solution (Ferric citrate solution) 0.1 ~ 5㎖ , potassium dihydrogen phosphate _{(KH 2 PO 4) 0.1 ~} 5g, magnesium sulfate heptahydrate _{(MgSO 4 .7H 2 O) 0.1} ~ Incubated at a pH of 5-9 in a medium containing 5 g, 0.1-5 g of sodium chloride (NaCl), 0.1-5 g of ammonium chloride (NH ₄ Cl) and 0.01-0.5 g of calcium chloride dihydrate (CaCl ₂ H ₂ O) Preferred yeast extract (Yeast extract) 0.5 ~ 2g, Disodium succinate hexahydrate (Disodium succinate hexahydrate) 5 ~ 20g, Absolute ethanol 0.2 ~ 1mL, Ferric citrate solution 0.5 ~ 2 ㎖, potassium dihydrogen phosphate _{(KH 2 PO 4) 0.2 ~} 1g, magnesium sulfate heptahydrate _{(MgSO 4 .7H 2 O) 0.2} ~ 1g, sodium chloride (Na It is more preferable that the medium is cultured at a pH of 6 to 8 in a medium containing 0.2 to 1 g of Cl), 0.2 to 1 g of ammonium chloride (NH ₄ Cl), and 0.02 to 0.1 g of calcium chloride dihydrate (CaCl ₂ H ₂ O).

In addition, the Bacillus thuringiensis ( Bacillus thuringiensis ) and Bacillus subtilis ( Bacillus subtilis ) 1 to 10g of peptic digest of animal tissue (Peptic digest of animal tissue), yeast extract (Yeast extract) 0.5 ~ 3g, It is preferably incubated at a pH of 4 to 10 in a medium containing 1 to 10 g of sodium chloride and 0.5 to 3 g of beef extract, and 3 to 7 g of peptic digest of animal tissue. More preferably, cultured at a pH of 6 to 8 in a medium containing yeast extract (Yeast extract) 1-2g, sodium chloride (3-7g) and beef extract (Beef extract) 1-2g.

In this case, as the carbon source used in the medium, maltose (Maltose), dextrose (Dextrose) or fructose (Fructose) may be used in a ratio of 0.1 to 1% by weight of the medium, and the growth rate and slime production of bacteria Considering, preferably maltose (Maltose) may be used in a 0.2 to 0.5% ratio.

As a material for adsorption of slime-forming bacteria in the present invention, a material having excellent porosity cation exchange ability may be used. Preferably, a high absorbent resin, a high porous resin, expanded vermiculite, pearlite, diatomaceous earth, and the like may be used.

If bacteria are used in the concrete manufacturing environment, the simple use of bacteria will cause growth to slow down or die because there is no moisture after curing the concrete. In order to create an environment in which bacteria can grow even inside the hardened concrete, the present invention has a porous structure (with an effective water content of 40% by volume and a porosity of 50% or more) by a myriad of pores, thereby providing a material having excellent moisture absorption and moisturizing power. To absorb and use bacteria.

The bacterial adsorption materials presented in the present invention have the property of adsorbing organic matter by exchange cations (Mg ^{2 +} , Ca ^{2 +,} etc.) present on the surface of the material to absorb the organic nutrients (medium components) necessary for bacteria and bacterial growth. do. In addition, the pH is 6-9, which is the ideal material for the optimum environment for bacteria to grow.

Immersion process may be used for adsorption of bacteria using the adsorbent. In this case, in the immersion conditions for the optimum absorption efficiency of bacteria, the mixing amount of the slime-formed bacteria used for the adsorption to the adsorbent is 50 when the adsorbent is the high absorbent resin or the high porous resin based on the weight of the bacterial culture. It is preferable that it is -200 times, It is more preferable that it is 100-150 times, When the said adsorption material is said expanded vermiculite, pearlite or diatomaceous earth, it is preferable that it is 5-20 times, and it is more preferable that it is 10-15 times. In addition, after immersing the adsorbent in the bacterial culture medium is preferably carried out by storage for 1 to 10 days at 40 ~ 80% humidity and 5 ~ 40 ℃ conditions, 2 ~ under conditions of 50 ~ 70% humidity and 10 ~ 30 ℃ temperature after immersion. More preferably, it is stored for 5 days.

On the other hand, the adsorbent is suspended when immersed in the culture solution with a specific gravity less than 1.0. Therefore, in the present invention, an effective adsorption method of bacteria is considered, and FIG. 4 exemplarily shows an adsorption pad (a) and a culture vessel (b) in which the adsorption pad is immersed.

Referring to FIG. 4, the adsorption material is introduced and discharged through the open / close clip 110, and when the plurality of adsorption pads 120 are used, the adsorption pads 120 are connected to each other by using the connecting rods 130. The counterweight 140 is connected to the lowermost suction pad 120 so that the pad 120 floats while maintaining a constant interval. In addition, FIG. 4 illustrates a threaded lid 150, a threaded opening 160, and an annular pin 170 to prevent contamination by other bacteria.

Mesh-type adsorption pads that can contain adsorbents, such as expanded vermiculite, are preferably manufactured using steel such as aluminum. The size of the mesh is determined in consideration of the particle size of the adsorbents used, but may be preferably used. Considering the type of the mesh eye size is 100㎛ ~ 5mm and the thickness of the mesh type adsorption pad is used in the range of 0.5 ~ 50mm, preferably the size of the mesh eye is 300㎛ ~ 3mm and the thickness of the mesh type adsorption pad The range of 1 to 30mm, more preferably the size of the mesh eye is 500㎛ ~ 1mm and the thickness of the mesh type adsorption pad can be used in the range of 2 ~ 10mm.

The length and width of the mesh adsorption pads vary with the diameter of the culture vessel. The mesh type suction pad is provided with an open / close clip to freely input and discharge the absorbent material, and an annular pin is installed for fixing. The mesh type suction pads are connected to each other using steel rods such as aluminum. In addition, the bottom layer of the mesh adsorption pad is provided with a counterweight to prevent floating, the weight of the counterweight for the immersion depth design is determined from the following equation (1).

[Equation 1]

In Equation 1, d is the immersion depth of the adsorption pad, W _L is the loading load, W _S is the fixed load, L and B is the length and width of the adsorption pad, γ _w is the unit volume weight of the culture. The fixed load (W _S ) among the elements for setting the target immersion depth (d) may change according to the volume and specific gravity of the adsorption pad, and accordingly, the load load (W _L ) is fluidly changed as a counterweight to target immersion. Depth can be secured.

As described above, in the present invention, the adsorption of bacteria using the adsorbent is performed by floating the adsorption pad 120 into the culture medium of the bacteria after injecting the adsorption material into the mesh-type adsorption pad 120, and the adsorption material contained in the adsorption pad 120. Can be suspended in the middle of the culture depth and allow for even absorption of bacteria and organic nutrients (medium components).

The final coating material is prepared by adsorbing the bacteria using the adsorbent and then mixing the adsorbent with the bacteria adsorbed with the binder.

The binder may be an ocher-based binder, α-half gypsum, blast furnace slag, fly ash, usually portland cement or magnesia-phosphate binder, especially considering the mechanism of chemical erosion of concrete sewer pipe and the sulfuric acid resistance mechanism of slime forming bacteria. Preferably, ocher-based binders, α-half gypsum or magnesia-phosphate binders may be used, and most preferably magnesia-phosphate binders may be used, given further bacterial sustainability.

The magnesia-phosphate binder exhibits a characteristic that a magnesia-phosphate complex is formed and cured by the reaction of magnesium oxide (MgO) and phosphate (PO ₄ ⁻ ). The pH and strength expression properties of the magnesia-phosphate binder are most affected by the mixing ratio of magnesium oxide and phosphate. In addition, a large amount of mixed cement (10 to 20% cement) can be expected to reduce the pH in the long term, and can also develop the required compressive strength (adhesive strength). Therefore, it is preferable to use magnesia-phosphate composite as the main binder of the coating material as a binder to maintain the proper pH (8-10) for the continuous growth of bacteria and to secure the required adhesion strength with the concrete structure.

On the other hand, since the efficiency and adhesion strength of the coating material are determined by the bacterial incorporation and growth rate, and the binder strength and amount, respectively, the mixing ratio of the adsorbent, the binder, and the fine aggregate (if necessary) containing bacteria is a very important factor that determines the performance of the coating material. to be. In particular, the condensation time of the binder is one of the most important performance in the coating of sewage pipe should be able to control this. Therefore, the formulation design of coating components for the required performance (flow, compressive strength and sulfuric acid resistance, etc.) is very important.

Here, the amount of the binder used when mixing the adsorbent and the binder adsorbed with bacteria is preferably 0.5 to 3 times the weight of the adsorbent adsorbed with bacteria, more preferably 1 to 1.5 times when the binder is an ocher-based binder. When the binder is α-half gypsum, blast furnace slag, fly ash, ordinary portland cement or magnesia-phosphate binder, it is preferable that the binder is 0.5-3 times the weight of the adsorbent adsorbed, and more preferably 1.5-2.5 times.

Bacteria adsorbed adsorbents and binders are weighed and mixed in a mixing vessel, and the final coating material is applied to the surface of the concrete structure exposed to chemical erosion and used to prevent chemical erosion. In this case, the coating thickness is preferably 0.5 to 10 mm, and more preferably 2 to 4 mm in terms of material economics, with the long-term performance of the coating material.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Slime Bacteria

In this embodiment, also holds at the National Research Center as a base material microorganisms as possible slime forming bacteria bakteo capsule called Bluetooth (Rhodobacter capsulatus ), Rhodoseudomonas palustris ), Bacillus thuringiensis and Bacillus subtilis bacteria were used.

Rhodobacter capsulatus ) and the basic medium for culturing Rhodoseudomonas palustris are shown in Table 1 below, and the basic medium for culturing Bacillus thuringiensis and Bacillus subtilis . Table 2 shows.

Rhodobacter capsulatus ), based on the medium, the carbon source (dextrose, maltose and frutose) was added 0.3% to the weight of the medium, respectively, the pH was adjusted to 6.8, and then 0.1% (v / v) of Rhodobacter capsularus ( Rhodobacter capsulatus ) was inoculated and cultured according to each carbon source. Inoculated bacteria were incubated using an incubator for 7 days at roughness 2,000 lux, 30 ° C. under anaerobic conditions. 5 shows the changed state after 7 days of cultured bacteria, and the culture state was confirmed by observing the change of the medium color with the naked eye.

Cultured Rhodobacter Rhodobacter capsulatus ) was examined under the microscope to confirm the shape and structure of the slime membrane. Rhodobacter capsulatus was stained using the Maneval's staining method to distinguish between slime membranes and cells. 6 shows the results of the microscopic observation, and the portion stained in pink is Rhodobacter ( Rhodobacter). capsulatus ) and the white part surrounding the cell is a slime (glycocalyx) membrane.

In order to evaluate the growth rate and slime production of bacteria according to the medium, the experiment was carried out as follows. Cultured Rhodobacter Rhodobacter The supernatant obtained by centrifuging capsulatus ) at 1,000 ppm for 30 minutes was added 1: 1 (v / v) with ethanol and precipitated at 4 ° C. for 12 hours to separate the slime membrane.

Figure 7 is a photograph showing the freeze-dried slime membrane for each medium, Figure 8 is Rhodobacter ( Rhodobacter capsulatus ) and a graph showing the amount of slime production, and FIG. 9 is Rhodobacter capsulatus ) is a graph showing the slime composition ratio.

Experimental Results Rhodobacter capsulatus ) showed the fastest growth rate at 0.89 g / L in maltose as shown in FIG. 8. In addition, also it cultured in maltose bakteo la capsule tooth (Rhodobacter slime of capsulatus ) showed the highest yield at about 0.25 g / L. In particular, as shown in Figure 9 Rhodobacter cultured in maltose ( Rhodobacter capsulatus ) produced the most slime per cell. However, Rhodobacter capsulatus cultured in fructose showed the smallest growth rate of 0.3 g / L, whereas slime per cell had about 21% of Rhodobacter capsulatus in Rhodobacter. capsulatus ) showed similar yields.

Slime bacteria based adsorbent

In order to immobilize the slime-formed bacteria and to adsorb organic nutrients (medium), the characteristics of adsorbents with excellent adsorption performance were first evaluated. The four absorbents evaluated in this example were T's high absorbent resin (Hydrogel), T's high porous resin (Hydrogel), S's expanded vermiculite, and S's pearlite. In general, bacteria are affected by adsorption by the surface structure, specific surface area, and surface hydrophobicity of the material (pederesn, 1990; Kidda et al., 1992). Thus, in this example, the surface of each adsorbent before adsorption of the bacteria. The structure and specific surface area were evaluated. Surface structures were observed using scanning electron microscopy (SEM). Specific surface area was also evaluated using Bruneter, Emmett, Teller (BET).

First, the highly absorbent resin is a three-dimensional network structure made by crosslinking a hydrophilic polymer such as a carboxyl group (COO-) and the like (Hwang, Jun-Seok, 2008). Highly absorbent resins have the property of absorbing and expanding hundreds of times their own weight due to their hydrophilicity. However, it is insoluble in water due to the crosslinking structure (Park Sang-bum, 1994). As shown in FIG. 10, the surface structure of the super absorbent polymer does not have surface pores, but pores of several hundred micrometers or more are present in a honeycomb shape. As a result, the highly absorbent resin is absorbed, adsorbed, and expanded by internal diffusion (Jun Hwang, 2008). The specific surface area of the high water absorbent resin was measured at 0.11 m 2 / g.

Next, the highly porous resin has pores of various sizes on the surface through the grinding of the high absorbent resin (Hydrogel) and can be rapidly absorbed, adsorbed, and swelled by capillary action. In particular, the highly porous resin has a porous structure in which pores are connected to each other, as shown in FIG. 11. The specific surface area of the high porosity resin was determined to be 3.54 m 2 / g.

Next, as shown in Fig. 12, the expanded vermiculite shows a surface structure in which a layer is formed as a comb layer between layers. It is a structure formed when the vermiculite is heated to 900 ~ 1,000 ℃, the moisture between the layers turns into steam (Song Jae-hong, 2009). Physical properties and chemical compositions of the expanded vermiculite are shown in Table 3 below.

Next, when perlite is crushed to 8-12 mesh or less and heated to 1,000 ° C. or more, the gasoline component contained in perlite changes and expands in the softened particles to form durable pores. As shown in Fig. 13, the surface structure of pearlite has a shape surrounded by a glassy film. Chemical compositions and physical properties of pearlite are shown in Tables 4 and 5, respectively.

Also cultured for each adsorbent in order to immobilize the bacteria in slime based bakteo la capsule tooth (Rhodobacter capsulatus ), Rhodoseudomonas palustris , Bacillus thuringiensis and Bacillus subtilis and soaked for 24 hours. Specifically, referring to Figure 4, each of the prepared bacterial culture solution in the culture vessel, the quantitative adsorbent is put into the adsorption pad (mesh size 700 × 700 ㎛, pad thickness 5mm, 5-stage connection) and into the culture vessel After immersion and suspension (the counterweight weight was determined according to Equation 1), the lid was closed and stored for 72 hours in an environment of 60% humidity and 20 ° C. Then, the adsorption pad was taken out of the culture vessel and the adsorption material to which bacteria were adsorbed was recovered through the opening and closing clip.

The average immersion depth (d) is a load weight (W _L) 10kg (5kg counterweight 2), (5 2kg suction pad) Dead load (W _S), 10kg of the suction pad when the bacteria are adsorbed adsorbent prepared, the suction pad The size (L × B = 0.3 m × 0.3 m) and the unit volume weight (γ _w ) of the culture solution were determined to be about 0.22 m from 1,000 kg / m 3.

Rhodobacter capsulatus , Rhodoseudomonas palustris , Bacillus thuringiensis and Bacillus subtilis adsorbed as the adsorbents prepared by the above bacteria. Scanning electron microscope (SEM) analysis results are shown in FIGS. 3 (using expanded calcite) and 4 (using high absorbent resin, observing internal and surface structure shapes) to evaluate adsorption performance. 3 shows the results for the case of not using the microorganism for comparison. As shown in FIG. 3 and FIG. 4, it can be seen that a good state of adsorption of bacteria (see the original part) is shown.

Rhodobacter is also known as Rhodobacter capsulatus ) was observed by scanning electron microscopy (SEM) of 1,000 ~ 10,000 magnification in order to evaluate the bacterial adsorption, the results are shown in Figure 14 and 15. The experimental results, also the formation of slime in all absorbent bakteo la capsule tooth (Rhodobacter capsulatus ) was adsorbed, and Rhodobacter capsulatus was observed as a cluster in the highly porous resin. It also showed a similar shape in expanded vermiculite.

Bacteria-adsorbed material-based coating

As described above, Rhodobacter capsulatus among the slime-forming bacteria was cultured for 7 days using maltose and dextrose selected as optimal medium conditions through slime production and growth evaluation. Cultured Rhodobacter Rhodobacter capsulatus ) was immersed for 24 hours by using a highly porous resin having excellent surface structure and specific surface area. Later, Rhodobacter capsulatus ) was prepared by using a high porosity resin and an ocher-based binder adsorbed to form a slime.

The ocher-based binder is a binder used to prepare the slime bacteria-based coating material, using the ocher-based binder of the company. The chemical composition ratio (X-ray fluorescence spectrometer; XRF) and X-ray diffraction analysis (XRD) of the loess-based binders used are shown in Table 6 and FIG. 16, respectively. The loess-based binder used was calcined at 850 ° C. The main components consisted of SiO ₂ and C3A (Al ₂ O ₃ ) as measured by chemical composition ratio and X-ray diffraction. Moreover, at 20 degreeC or less and 55 degreeC or more, the amorphous peak which is an amorphous crystalline phase was shown. Specific gravity and powder degree are 2.8 and 3,200 cm 2 / g, respectively.

Bacterial adsorbed high-porous resin and ocher-based binder (ocher cement) were weighed and mixed in a mixing vessel for at least 3 minutes to prepare a coating material, and the following experiments were carried out by coating with concrete using a brush. . The thickness of the concrete coated with the coating material was measured using a vernier caliper after drying for 12 hours, the error range was ± 0.5mm.

Experimental Example 1 (Utilization bacteria: Rhodobacter capsularus ( Rhodobacter capsulatus ))

In order to evaluate the sulfuric acid resistance of the concrete coated with the slime bacterial coating material, the coating material mixing experiment was classified into three groups and a total of 18 combination experiments were performed. The mixing details in each group for mixing the coating material of the concrete are shown in Table 7 below.

Variables in each group are binder replacement rate, bacterial incorporation of adsorbent, and thickness of coating. In the first group, the substitution rate of the binder was the main variable, and the range of the substitution rate was set at 1 to 2 at 100 times the weight of bacteria incorporation into the adsorbent. The second group was fixed at the binder replacement rate determined through the experimental results of the first group, the main variable is the amount of bacterial incorporation into the adsorbent, the range is 50 to 200 times the weight. In the third group, the binder replacement rate and the bacterial incorporation rate of the adsorbent were fixed according to the test results of the first group and the second group. In all groups, concrete and bacteria-free coatings were compared and analyzed. Comparative analysis results with the existing technology will be described later.

The mixing details of the concrete for applying the coating material in this Experimental Example are shown in Table 8 below. The water-cement ratio was set to 0.45 in consideration of the design strength of the site-cast concrete for sewage facilities. The cement used was S type 1 ordinary portland cement. Fine aggregates and coarse aggregates were made of natural sand with a maximum diameter of 5 mm or less, and crushed gravel with a maximum diameter of 25 mm, respectively. The sand and crushed gravel used are 2.62 and 2.6, respectively, and the assembly rates are 2.5 and 6.3, respectively. The moisture state of the aggregates used in the mixing was to maintain the surface dry saturation state.

A 300 liter capacity mixer was used to mix the concrete. Briefly describing the mixing method, first, the coarse beam was added to a 300 liter mixing vessel and coarse beam was added for 1 minute, and the cement was added for 1 minute and 30 seconds. Finally, water was added and the mixture was mixed for about 2 minutes. All formulations were free of water and air entrainers. In order to evaluate the sulfuric acid resistance of concrete, it was placed in a Φ100 × 200 circular specimen mold. The cast specimens were demolded after 1 day and cured until 28 days of age in a constant temperature and humidity environment. Curing temperature is 20 ± 2 ℃ and humidity is 60 ± 5%.

The method of evaluating the performance of the coating material and the coating material coated coating material is as follows.

[Coating Material Evaluation Method]

(1) Hydration Product

In order to evaluate the hydration product of the coating material, samples were taken at 28 days of age depending on the presence of concrete and bacteria. The sample was ground to 1 mm or less to measure X-ray diffraction analysis (XRD). X-ray diffraction analysis (XRD) is an analytical device in which X-rays are scattered by the crystal layer on the surface of a sample with an angle to obtain a diffraction image. This was used to analyze the main diffraction peaks of the hydration products of each sample.

(2) Internal microstructure and elemental analysis

Scanning electron microscope (SEM) and elemental analyzer (EDS) were used to analyze the internal microstructure and chemical components of the sample. An electron beam was emitted to the sample to check the internal microstructure at 5,000 to 30,000 magnification. In addition, the type and content of the elements contained in the surface were investigated by using X-ray energy emitted during electron beam irradiation.

[Concrete Performance Evaluation Method]

In order to evaluate sulfuric acid resistance of concrete coated with coating material according to the main variables, it was immersed in chemical sample solution according to JIS K 8951 standard. Sulfuric acid was dissolved in distilled water at a concentration of 5% as a chemical sample solution, and the solution was replaced every 14 days in consideration of the dilute concentration of the prepared sulfuric acid solution.

(1) appearance investigation

In order to evaluate the performance degradation of concrete immersed in 5% sulfuric acid solution, the change of appearance was visually evaluated before and after immersion in the solution, on the 1st, 3rd, 7th and 28th days of immersion.

(2) sulfuric acid penetration depth

In order to measure the depth of sulfuric acid penetration of concrete immersed in 5% sulfuric acid solution, as shown in FIG. 17, the cross section was cut at 28 days of immersion to observe the erosion depth.

(3) Surface structure and reaction product of concrete eroded by sulfuric acid

In order to evaluate the surface structure and the reaction product of the concrete immersed in a 5% sulfuric acid solution, as shown in FIG. An X-ray diffraction analysis (XRD) apparatus was used to evaluate the reaction product of the sample. In addition, electron microscopy (SEM) and elemental analyzer (EDS) were used to evaluate the type and content of elements contained in the internal microstructure and surface.

(4) weight

For the measurement of the weight, the mold immersed in a 5% sulfuric acid solution was taken out and used for 1, 3, 7 and 28 days. With respect to the mold from which the solution was removed, the surface of the surface was dried with a towel or the like, dried in a drying furnace at a temperature of 105 ± 5 ° C., and the mass W (g) was measured using a 1g scale. In addition, in order to ignore the weight of the coating material, as shown in Equation 2, it is expressed as the ratio of the weight of the number of immersion days to the mass before immersion in sulfuric acid solution.

[Equation 2]

In Equation 2, W represents the weight (%), W _t represents the mass (kg) of the specimen by immersion days, W ₀ represents the specimen mass (kg) before immersion.

(5) compressive strength

In order to evaluate the compressive strength, molds immersed in the solution were used by taking out Φ100 × 200 molds in 1, 3, 7 and 28 days using Φ100 × 200 mold according to KS (2013). After removing the mold from the surface of the mold with a towel, the solution was dried at a temperature of 105 ± 5 ° C. in a drying furnace, and the compressive strength of the concrete was measured using a 500 kN universal testing machine. In addition, the compressive strength before immersion in 5% sulfuric acid solution was evaluated to evaluate the decrease in compressive strength by sulfuric acid immersion days.

(6) dynamic modulus

To evaluate the dynamic modulus of elastic modulus, the dynamic modulus of elastic modulus was evaluated according to the first resonance frequency. The measurement was used by taking out the mold immersed in the solution on 28 days of immersion. It was measured using a resonance frequency measuring instrument (ERUDITE) of 500 ~ 10,000Hz capacity as a measuring device. In order to compare the degree of deterioration of the central part and the surface part of the test specimen eroded by sulfuric acid, the measured part was measured as an average value three times in each of the central part and the surface part. The dynamic modulus by the resonance frequency test was expressed by Equations 3 and 4 Calculated by

[Equation 3]

[Equation 4]

In Equation 3, E _p represents the dynamic modulus of elasticity (MPa), W represents the mass of the specimen (kg), F represents the primary resonance frequency (Hz) of the longitudinal vibration, and in Equation 4 L represents the length of the specimen ( mm), A represents the cross-sectional area (mm 2) of the specimen.

Coating material evaluation result

(1) Hydration Product

X-ray diffraction analysis (XRD) patterns according to the presence of bacteria in the coating material and the type of medium are shown in FIGS. 18 and 19. As a coating material containing the bacteria to be evaluated, bacteria cultured for 7 days in maltose and dextrose are used, and the amount of bacterial incorporation compared to the high porosity resin is 100 times the weight, soaked for 24 hours, and adsorbed. The ash ratio was made to be 1: 1.5. On the other hand, the coating material is not mixed with bacteria was absorbed by dipping the high porous resin in distilled water. Distilled water and adsorbent-binder ratios were the same as those of the high porous resin.

X-ray diffraction analysis (XRD) showed that the gypsum crystal phase was found at around 10 ° C. for the coating material without bacteria. Gypsum formed causes a softening reaction of the coating material, which reacts with tricalcium silicate (C3S), a hydration reaction product, to form ettringite. Therefore, the coating material that is not mixed with bacteria is likely to increase in volume due to the formed gypsum and ettringite, thereby causing expansion and cracking. On the other hand, in the coating material mixed with bacteria, a large amount of silica silicate minerals (SiO ₂ , Quartz) were formed. SiO ₂ is a fine particle having a particle size of 0.1 ~ 1㎛ high reactivity and has the effect of filling the pores of cement particles. For this reason, as described below, the specimens containing bacteria showed higher compressive strength, which is considered to be due to the improved internal density due to SiO ₂ in the coating material (Shiand Day, 2001). Ghosh (2009) also reported that SiO ₂ was precipitated in mortars containing Shewanella bacteria that formed proteins around cells, thereby enhancing their strength. However, no reports have been made on SiO ₂ formed by Rhodobacter capsulatus at this time. Therefore, it is expected that new organic-inorgainc crystals will be formed by slime, proteins, amino acids, etc., which are formed by bacteria. In addition, Rhodobacter cultured in maltose medium ( Rhodobacter capsulatus ) -incorporated coating material increased the number of CaCO ₃ Intensity peaks compared to the bacteria-free coating material, but the dextrose medium did not show any effect. Therefore, the species specificity of the bacteria and the medium (enzyme) determine the characteristics of the mineral crystal and it is expected that the species specificity and the medium (enzyme) effect can be imparted to improve the durability of the coating material.

(2) internal microstructure

20 and 21 show internal microstructures depending on the presence of bacteria in the coating material and the type of the medium. In the case of coatings that do not incorporate bacteria, there are a number of internal micropores, gypsum and Ettringite. On the other hand, bacteria-incorporated coatings showed little internal micropores, because of the improved density due to SiO ₂ formed (Shi and Day, 2001). In addition, also in the inner coating bakteo la capsule tooth (Rhodobacter capsulatus ) to form colonies and appear in clusters.

Concrete performance evaluation result (the first group)

(1) appearance change

The main variable of the first group is the bacterial adsorbent-binding ratio, and the appearance state of the test specimens by immersion days according to sulfuric acid immersion is shown in FIGS. 22 and 23. In the case of appearance change of the uncoated test specimen (C), as the number of immersion days increased, the paste disappeared and the aggregate was exposed. In addition, in the case of the change of the appearance of the test specimens (G1-B1, G1-B1.5 and G1-B2.0) that do not contain bacteria, the coating material was severely peeled off as the adsorbent-binding ratio decreased. The test specimen having a ratio of 1.0 exhibited a similar appearance to Test Sample C at 28 days of immersion. In the case of the change in appearance by immersion days of the slime bacteria-based specimens, the coating material peeled off at the corners as the immersion days increased with the adsorbent-binding ratio of 1.0. The effect on sulfuric acid erosion was minimal.

(2) sulfuric acid penetration depth

FIG. 24 shows the result of performing image analysis by dividing the cross section of the Φ100 × 200mm specimen into four sections and cutting the cross section at 28 days of immersion to observe the depth of sulfuric acid penetration of the test specimen according to the binder substitution rate. The depth of penetration was defined as the distance from the surface of the specimen to the point where white discoloration occurred. The test sample (C) which was not coated with a coating material decolorized about 3.39 mm on the surface. In addition, in the case of the bacteria-incorporated specimens (G1-B1.0, G1-B1.5 and G1-B2.0), the white discoloration phenomenon was larger as the binder substitution rate decreased. On the other hand, all the specimens containing bacteria did not show white discoloration on the surface of the concrete regardless of the dropping of the coating material.

(3) surface microstructure and reaction products

The results of analyzing the main diffraction peaks of the reaction product of the sample taken from the concrete surface (0-1 cm) by using X-ray diffraction analysis (XRD) are shown in FIGS. 25 and 26. Scanning electron microscope (SEM) and elements The tissue structure and chemical member analysis results of the samples collected using the analyzer (EDS) are shown in FIGS. 27 to 29. All test samples in the main reaction product of plaster _{(Gypsum; CaSO 4 · H 2} O), silica (Quartz; SiO ₂₎ and sulfur dioxide; a peak representing (Sulfur Oxide SO ₂₎ was produced. In particular, the intensity of gypsum (CaSO4 · H ₂ O) and sulfur dioxide (SO ₂ ), which are reaction products of test specimen (C) without coating, was formed strongly, and a large amount of gypsum (CaSO 4 · H ₂ O) was also formed in the internal microstructure. And the shape of Ettringite were confirmed. For this reason, the C test specimens were judged to have a lower compressive strength than the other test specimens. In addition, the bacteria-free test specimens (G1-B1.0, G1-B1.5 and G1-B2.0) showed a similar tendency to the C test specimens regardless of the adsorbent-binding ratio. On the other hand, as the specimen mixed with bacteria increased as the adsorbent-binding ratio, the number and intensity of the peaks of quartz (SiO ₂ ) were stronger than that of the C specimen. In the internal microstructure, as the adsorbent-binding ratio increased, the internal density was improved, and a small amount of Ettringite was observed. In addition, the results of EDS analysis showed a tendency of high elemental Si in the test specimens containing bacteria, and Mg, Na, Cl, and P were further confirmed due to the medium component.

(4) weight change

Figure 30 shows the weight change by number of days of sulfuric acid immersion of the first group. The test specimen (C) without the coating material exhibited a weight loss of about 6-11% between 7 and 28 days of immersion. In addition, the specimens containing no bacteria (G1-B1.0, G1-B1.5 and G1-B2.0) tended to decrease with decreasing adsorbent-binding ratio at 3 days of soaking, and at 28 days of soaking. In test specimens with an adsorbent-binding ratio of 1.5, the largest decrease was about 4%. On the other hand, test samples containing bacteria cultured in maltose showed no significant effect on adsorbent-binding ratio on weight change at 3 days of immersion. However, at 28 days of immersion, the steepest decrease was found to be about 8% in the specimens with an adsorbent-binding ratio of 1.0. In the case of the test specimen incorporating bacteria cultured in dextrose, the effect of adsorbent-binding ratio on the change of weight by immersion days was insignificant.

(5) compressive strength

FIG. 31 shows the compressive strength reduction ratio (f _ck / f _{ck (0)} ) for each immersion day according to sulfuric acid immersion of the first group. Where f _ck is the compressive strength of the specimen according to the number of immersion days and f _{ck (0)} is the compressive strength of the specimen before sulfuric acid immersion. The compressive strength reduction ratio of the test specimen without the coating material was about 18% at 28 days of immersion, indicating a sharp drop in strength. On the other hand, the compressive strength reduction ratios of the test specimens containing no bacteria (G1-B1.0, G1-B1.5 and G1-B2.0) were similar regardless of the adsorbent-binding ratio and immersion days. On the other hand, the compressive strength reduction ratio of the test specimens incorporating bacteria cultured in dextrose medium increased or showed a similar tendency as the immersion days increased regardless of the adsorbent-binding ratio. On the other hand, the compressive strength reduction ratio of the test specimens mixed with bacteria cultured in maltose medium was about 22-35% higher than the test sample without coatings, regardless of the number of immersion days and the adsorbent-binding ratio. It was about 3 ~ 10% higher than the test body. This is because the internal density of the coating material is improved due to the slime (glycocalxy) and silica component (SiO ₂ ) formed by bacteria.

(6) dynamic modulus

On the 28th day of sulfuric acid immersion, the ratio of elastic modulus reduction (E _{d_c} / E _{d_c (0)} ) and the surface modulus of elastic modulus (E _{d_s} / E _{d_s (0)} ) at the _{center of the test body} are shown in FIGS. 32 and 33, respectively. Indicated. Where E _{d_c} is the central elastic modulus at 28 days of immersion, E _{d_s} is the dynamic modulus at the surface, E _{d_c (0)} is the central elastic modulus at C specimens not eroded by sulfuric acid, and E _{d_s (0)} is It is the coefficient of dynamic elasticity of the surface part in test specimen C which is not eroded by sulfuric acid. The ratio of the reduction of the coefficient of dynamic modulus of the central portion of the test piece C, which was not coated with the coating material, was about 33%, and the ratio of the decrease of the coefficient of dynamic elasticity of the surface portion was about 50%. The ratio of decreasing the elastic modulus of the central portion of the test specimens (G1-B1.0, G1-B1.5, and G1-B2.0) that did not contain bacteria was lower as the adsorbent-binding ratio decreased. The reduction ratio was about 27 ~ 31% lower regardless of adsorbent-binding ratio. On the other hand, the ratio of decrease in dynamic modulus of the central part of the test specimen containing bacteria was higher as the adsorbent-binding ratio increased, regardless of the type of medium. High.

Concrete performance evaluation result (the second group)

(1) appearance change

The main variable of the second group is the amount of bacterial incorporation, and the appearance of concrete according to sulfuric acid immersion is shown in FIGS. 34 and 35. Test specimens containing no bacteria (G2-W50, G2-W100 and G2-W200) were exposed to concrete due to peeling of the coating material on the surface at 28 days of immersion regardless of the amount of distilled water mixed. On the other hand, slime bacteria-based test specimens showed no significant effect until 7 days of immersion except 50 times the amount of bacteria mixed with adsorbent, and at 28 days of immersion, there was little coating material on the surface regardless of the media type and the amount of bacteria mixed with adsorbent. Peeling occurred.

(2) sulfuric acid penetration depth

36 shows the results of image analysis by cutting the cross section to observe the depth of sulfuric acid penetration of the test specimen according to the amount of bacterial incorporation compared to the adsorbent at 28 days of immersion. In all specimens (G2-W50, G2-W100, and G2-W200) that did not contain bacteria, the surface of the concrete was decolorized, and the surface of the concrete was about 3.71mm in the G2-W50 specimen having 50 times the amount of distilled water mixed with the adsorbent. It occurred the most. On the other hand, the test sample containing bacteria showed dropout of the coating film at less than 100 times the amount of bacteria mixed with the adsorbent, but did not show white discoloration on the concrete surface. This is because the internal density was improved due to the internal slime formation and the silica component (SiO ₂ ) formed by bacteria.

(3) internal microstructure and reaction products

37, 38, 39 and 40 show the main diffraction peaks (XRD), the surface structure (SEM) and the elemental analysis result (EDS) of the reaction products according to the main variables of the second group, respectively. As a result of the analysis, the specimens containing no bacteria showed strong intensities of gypsum and sulfur dioxide regardless of the amount of distilled water mixed with the adsorbent. The needle-like Ettringite shape was also confirmed in the internal microstructure, and a large amount of S (sulfur) element was measured by elemental analysis. This reaction product causes the expansion and softening of the concrete, and breakage and cracking of the tissue structure. On the other hand, test specimens containing bacteria tended to increase the number and intensity of SiO ₂ peaks as the amount of bacterial incorporation increased compared to the adsorbent, and a large amount of slime film formation and internal density in the internal structure were observed. The improvement was confirmed. As a result of the EDS analysis, as in the first group, the specimens containing G2-M200 and G2-D200 containing bacteria 200 times the weight of the adsorbent showed a tendency of high Si element due to SiO ₂ , and Mg, Na due to the medium and bacteria. , Cl and P and the like were further confirmed.

(4) weight change

Figure 41 shows the weight change by number of immersion days according to the amount of bacteria mixed with the adsorbent. The weight change of test specimens (G2-W50, G2-W100 and G2-W200) that did not contain bacteria decreased as the amount of distilled water mixed with the adsorbent increased with the number of immersion days. On the other hand, the weight change at 3 days of immersion of the bacteria-incorporated test specimens had little effect on the presence of medium and the amount of bacterial incorporation. However, on 28 days of immersion, the test samples containing G2-M50 and G2-D50 containing 50 times the bacteria to the weight of the adsorbent showed the greatest weight reduction compared to the other samples containing the bacteria.

(5) compressive strength

42 shows the compressive strength reduction ratio (f _ck / f _{ck (0)} ) according to sulfuric acid immersion of the second group. The compressive strength reduction ratio of the test specimens (G2-W50, G2-W100, and G2-W200) that did not contain bacteria increased by 9 ~ 11% at 7 days of immersion regardless of the distilled water incorporation rate compared to the adsorbent, and 28 days of immersion. Esau increased about 12-15%. The compressive strength reduction ratio of the test specimens incorporating the bacteria at 3 days of immersion had little effect on the amount of bacterial incorporation and the presence or absence of the medium. However, the compressive strength reduction ratio of the test sample containing bacteria was about 30% higher than the test sample without coating material at 28 days of immersion. In addition, the ratio of lowering the compressive strength of the test body having 100% of bacteria incorporation to the adsorbent was about 4% higher than that of the test body having 100 times the amount of distilled water in the adsorbent. This is because the internal density of the coating material is improved due to the slime (glycocalxy) and silica component (SiO ₂ ) formed by bacteria.

(6) dynamic modulus

43 and 44, respectively, on the 28 days of sulfuric acid immersion days, the ratios of decreasing the elastic modulus of elasticity (E _{d_c} / E _{d_c (0)} ) and the surface modulus of elasticity ( E _{d_s} / E _{d_s (0)} ). The central elastic modulus reduction ratio was similar in the range of 0.97 ~ 1.08 in all formulations. On the other hand, the ratio of lowering the elastic modulus of the surface portion decreased as the amount of distilled water mixed with the adsorbent increased in the test specimens containing no bacteria (G2-W50, G2-W100 and G2-W200). This is because the strength of the coating material is lowered due to the increase in the water-binder ratio. On the other hand, the ratio of decrease in dynamic modulus of the central part of the test specimen containing bacteria increased with increasing amount of bacteria compared to the adsorbent regardless of the type of medium. In addition, the ratio of decrease in dynamic modulus of the surface portion of the specimen incorporating the bacteria was about 1.00 to 1.05, which was similar to that before the immersion.

Concrete performance evaluation result (the third group)

(1) appearance change

45 and 46 show appearance states of the test specimens immersed in sulfuric acid. In the previous experiment, the appearance of concrete for sulfuric acid immersion on day 1 was not measured because it showed no change. Appearance change of specimens without bacteria in 7 days of immersion (G3-C0.5, G3-C1.0 and G3-C3.0) had a significant effect on the coating thickness except for the specimen with 0.5mm coating thickness. It is not shown. In addition, all the specimens incorporating bacteria had little effect on coating thickness and media type. On the other hand, on 28 days of immersion, the change in appearance of the test specimens containing no bacteria (G3-C0.5, G3-C1.0 and G3-C3.0) showed a greater dropout of the coating material than the test sample containing the bacteria. In particular, the G3-C0.5 specimen having a coating thickness of 0.5 mm exposed the coating material to expose the concrete. On the other hand, the change in appearance of the test specimen incorporating bacteria showed a greater peeling of the coating material as the coating thickness was thinner.

(2) sulfuric acid penetration depth

47 shows the results of image analysis by cutting the cross section to observe the depth of sulfuric acid penetration of the test specimen according to the coating thickness at 28 days of immersion. In all specimens (G3-C0.5, G3-C1.0 and G3-C3.0) that did not incorporate bacteria, the surface was exposed due to the coating film dropping from 7 to 28 days of immersion. As a result, the depth of sulfuric acid penetration of specimens with a coating thickness of 1.0 mm or less was about 2.99 to 2.15 mm, which was similar to that of uncoated specimens (C), whereas the concentration of sulfuric acid was not measured in spite of the dropping of the coating film. Did.

(3) Surface structure and reaction product

48, 49, 50 and 51 show the main diffraction peaks (XRD), the surface structure (SEM) and the elemental analysis results (EDS) of the reaction products according to the main variables of the third group, respectively. As a result, peaks representing the major reaction products Gypsum (G), Quartz (Quartz; Q), Sulfur Oxide (S), and Calcium Carbonate (CaCO ₃ ) were produced in all specimens. In particular, regardless of the presence of bacteria in the coating thickness of less than 1mm the intensity of the reaction product gypsum and sulfur dioxide (Intensity) was formed strongly, and the shape of a large amount of gypsum and Ettringite in the internal microstructure was confirmed. EDS analysis also showed that the diffraction peaks were relatively low due to the consumption of calcium to form gypsum and ettringite. On the other hand, test specimens containing bacteria having a coating thickness of 3.0 mm showed a tendency to increase the intensity of SiO ₂ regardless of the type of medium. As a result, it is considered that the compressive strength and the sulfuric acid resistance improvement are higher than those of the other specimens. In addition, as shown in the EDS analysis of the first group and the second group showed a tendency to appear high Si element, Mg, Na, Cl and P was further confirmed due to the medium and bacteria.

(4) weight change

52 shows the change in weight by the number of days of sulfuric acid immersion in the third group. Test specimens that did not incorporate bacteria (G3-0.5, G3-1.0, and G3-3.0) showed no significant change regardless of coating thickness at 3 days of immersion. On the other hand, at 28 days of immersion, the weight was reduced to about 8% in the specimen having a thickness of 0.5 mm. On the other hand, test samples containing bacteria by immersion days showed about 1 ~ 2% higher or similar tendency than test samples containing no bacteria regardless of the type of medium and coating thickness.

(5) compressive strength

FIG. 53 shows the compressive strength reduction ratio (f _ck / f _{ck (0)} ) for each immersion day according to sulfuric acid immersion of the third group. The compressive strength reduction ratios of the test specimens containing no bacteria (G3-0.5, G3-1.0 and G3-3.0) were increased to about 8-10% with increasing immersion days except for 0.5 mm of coating thickness. The compressive strength reduction ratio of the test specimens incorporating bacteria cultured in maltose medium tended to increase with increasing coating thickness at 3 days of immersion, and similar trends were observed in dextrose medium. In addition, the compressive strength reduction ratio at 28 days of immersion was the largest in the test specimen having a coating thickness of 1.0 mm or more, regardless of the media type. Accordingly, the ratio of lowering the compressive strength of the test specimen of G3-M3.0 containing bacteria was about 36% higher than that of the test specimen without coating material at 28 days of immersion, and the test specimen of G3-3.0 containing bacteria was not found. 4 ~ 6% higher than that. It is believed that the penetration of sulfuric acid is suppressed due to the improvement of the slime film and the internal density formed in the coating material, thereby improving the compressive strength.

(6) dynamic modulus

54 and 55 show a ratio of decreasing the elastic modulus of elasticity (E _{d_c} / E _{d_c (0)} ) and the surface modulus of elasticity (E _{d_s} / E _{d_s ) at} the center of the test specimen according to the coating thickness at 28 days of immersion of sulfuric acid, respectively. ₍₀₎ ). The ratio of dynamic modulus reduction in the center showed a similar tendency with or without bacterial incorporation. On the other hand, the elastic modulus reduction ratio of the surface portion of the test specimen having a coating thickness of 1.0 mm or less showed a similar tendency regardless of the presence of bacteria and the type of medium. However, the ratio of decrease in dynamic modulus of the surface portion of the test specimen having a coating thickness of 3 mm was about 21% higher than that of the test sample containing bacteria grown in maltose. In addition, it was about 8% higher than the test specimen of G3-D3.0 containing bacteria cultured in dextrose. This is thought to be due to the reaction product according to the amount of slime produced by bacteria and the erosion of sulfuric acid.

Comparative analysis results with existing technologies

Hereinafter, a result of experimenting with a total of four formulations to compare the present invention with the conventional epoxy coating material for the sulfuric acid behavior in concrete will be described. Specimen said concrete coated with an epoxy coating 'Epoxy', culturing the non-incorporated into the coating of bacteria 'Hwangtoh', concrete coated with a coating material mixed with the bacterial culture in a maltose medium in 'Maltose', dextrose medium Concrete coated with a coating material containing bacteria is represented as ' Dextroes '. Epoxy coating material was used by the company S, and the epoxy resin and the amine-based curing agent was applied by mixing 1: 1, the main components and physical properties are shown in Table 9 below. The slime bacteria-based coating material was selected as shown in Table 10 through the above experiment, and further blending was performed under the same conditions in order to evaluate the performance of the coating material according to the presence of bacteria. All specimens were applied identically with a brush. In addition, in order to make the coating thickness the same, the epoxy coating material was applied once, dried for 12 hours, and then applied twice. The coating thickness was fixed at 1.0 mm ± 0.05 mm. In order to evaluate the sulfuric acid resistance of concrete, the change in appearance, weight, compressive strength and dynamic modulus of the concrete immersed in 5% sulfuric acid solution were evaluated according to JIS K 8951.

(1) appearance change

56 shows the appearance state of the test body by immersion days according to sulfuric acid immersion. Appearance change of the control (Control) not coated with the coating was exposed to the aggregates disappeared as the number of immersion days increased. At 7 days of immersion, the appearance of concrete coated with epoxy coating caused cracking and swelling. On the other hand, concrete coated with bacterial coatings did not show any change. In 28 days of immersion, the change of appearance of epoxy-coated concrete resulted in the dropout of coating material, and the concrete coated with bacteria-free coating material showed similar tendency. However, the appearance of the concrete coated with the slime bacteria-based coating material showed a dropout of the coating material, but it was smaller than the other test specimens.

(2) weight change

57 shows the weight change of sulfuric acid immersion days. The control group without the coating showed a weight loss of about 6-11% between 7 and 28 days of immersion. In addition, epoxy coated concrete (Epoxy) showed a sharp weight loss of about 5% in 28 days of immersion. On the other hand, the weights of all test specimens except for the control without the coating material (Control) showed a similar tendency with a decrease of about 5-6% at 28 days of immersion.

(3) compressive strength

58 shows the compressive strength reduction ratio (f _ck / f _{ck (0)} ) by immersion days according to sulfuric acid immersion. The compressive strength reduction ratio of the test specimen without the coating material exhibited a strength reduction of about 22% at 28 days of immersion. The compressive strength reduction ratio of the test specimen coated with the epoxy coating material decreased as the number of immersion days increased. On the other hand, the compressive strength reduction ratio of the test specimens containing bacteria increased with increasing immersion days, and the compressive strength reduction ratio of 28 days of immersion was higher than that of the test specimens without bacteria (Hawngtoh). In comparison with the test body coated with the epoxy coating material, it was shown to be about 26 to 27%. This is because the internal density is improved due to the reaction product of the coating material according to the number of immersion days, the slime film formed by bacteria and the silica component.

(4) dynamic modulus

59 and 60 are respectively sulfate immersion days 28 days copper modulus lowering of the center of the test piece in a _{non-(E d_c / E d_c (0} )) and the surface of the copper modulus lowering ratio _{(E d_s / E d_s (0} )) Indicated. The central elastic modulus reduction ratio was similar in the range of about 0.97 ~ 1.06 in all specimens except the control without coating. On the other hand, the ratio of decrease in dynamic modulus of the surface portion was about 6% higher than that of the test specimen coated with the epoxy coating (Hawngtoh), but about 9% lower than the test sample containing the bacteria.

Experimental Example  2 (conjugated bacteria: Rhodesudo Monas Fallustris ( Rhodoseudomonas  palustris ) And Bacillus thuringiensis ( Bacillus thuringiensis ))

Rhodoseudomonas palustris ) and Bacillus thuringiensis as binders for the production of bacterial incorporation coatings, α-hemihydrate gypsum with a specific gravity of 2.67 g / cm 3 and blast furnace slag with a specific gravity of 2.91 g / cm 3 GGBS) is used in a weight ratio of adsorbent-impregnated culture medium and 2.2: 1 (adsorbent-binding material ratio 2.2) and a binder mixed with a 1: 1 weight ratio of GGBS). The experiment was conducted in the same manner as in Experimental Example 1, except that the results were as follows.

(1) appearance change

61 shows the external appearance of the test specimens according to the sulfuric acid immersion days. All specimens did not show any apparent change in appearance at days 1 and 3 of soaking age. After 7 days of immersion, the test specimens using the coating material mixed with the concrete specimen (OPC) and Bacillus thuringiensis showed erosion in appearance, especially in the case of the concrete specimen (OPC). Appearance erosion was indicated. Rhodoseudomonas Test specimens using the coating material incorporating palustris ) did not show any noticeable appearance change.

(2) compressive strength

62 shows the change in compressive strength of the test specimens depending on the immersion age. Rhodoseudomonas In the case of coatings containing palustris ) and Bacillus thuringiensis , the compressive strengths increased by 45% and 25%, respectively, until 7 days of immersion, followed by a 45% reduction in compressive strength by 28 days. Indicated. On the other hand, the concrete specimens (OPC) showed a decrease in compressive strength of about 5% at 7 days of dipping and about 10% at 28 days of dipping.

(3) mass change

63 shows the change in mass of the test specimen depending on the immersion age. All specimens showed a decrease in mass with increasing immersion age. In the case of concrete specimens (OPC), a mass reduction of about 12% was observed at 28 days of immersion age, and 28 days of immersion age when coatings containing Rhodoseudomonas palustris and Bacillus thuringiensis were used. Showed a mass reduction of about 5%.

(4) Microstructure Analysis (SEM)

64 shows the results of the microstructure analysis for evaluating the adsorption of bacteria after 28 days of immersion in 5% sulfuric acid solution. Bacteria formation on the surface of the particles was confirmed in the coating material incorporating Rhodoseudomonas palustris and Bacillus thuringiensis .

Experimental Example  3 (conjugated bacteria: Rhodobacter Capsule ( Rhodobacter capsulatus ), Rhodesudo Monas Fallustris ( Rhodoseudomonas palustris ), Bacillus Turingensis ( Bacillus thuringiensis ) And Bacillus subtilis ( Bacillus subtilis ))

Rhodobacter capsulatus ), Rhodoseudomonas palustris , Bacillus thuringiensis and Bacillus subtilis as binders for the production of bacterial incorporation coating materials as common binders with specific gravity of 3.15 g / cm3 Binder mixture of portalnd cement (OPC) and blast furnace slag (GGBS) with specific gravity of 2.91 g / cm3 in a 1: 1 weight ratio was mixed with a medium in which the adsorbent was immersed and a weight ratio of 2.2: 1 (adsorbent-binder ratio 2.2). The experiment was conducted in the same manner as in Experimental Example 1, except that the adsorbent was used in a bacterial culture medium: expansive vermiculite weight ratio of 10: 1. The experimental results are as follows.

(1) mass change

65 shows a change in the mass of the test specimen depending on the immersion age. The mass change at 7 days of immersion in sulfuric acid solution decreased by about 4% when only water and bacteria medium were used as the mixing water, and about 3 ~ 8% when using the bacterial inoculum culture solution as the mixing water. It was.

(2) compressive strength

66 shows the change in compressive strength of the test specimen depending on the immersion age. Test specimens using only water and bacterial media as the blended water decreased the compressive strength as the immersion age increased, whereas the compressive strength did not appear to decrease as the immersion age increased.

Experimental Example  4 (conjugated bacteria: Rhodobacter Capsule ( Rhodobacter capsulatus ), Rhodesudo Monas Fallustris ( Rhodoseudomonas palustris ), Bacillus Turingensis ( Bacillus thuringiensis ) And Bacillus subtilis ( Bacillus subtilis ))

Rhodobacter capsulatus ), Rhodoseudomonas palustris , Bacillus thuringiensis and Bacillus subtilis as binders for the production of bacterial incorporation coating materials as α-half gypsum (2.67 g / cm 3) A binder mixed with α-hemihydrate gypsum) and a blast furnace slag (GGBS) having a specific gravity of 2.91 g / cm3 in a 1: 1 weight ratio was mixed with a medium in which the adsorbent was immersed and a weight ratio of 2.2: 1 (adsorbent-binder ratio 2.2). A coating material was prepared in the same manner as in Experimental Example 1 except that the adsorbent was used as the bacterial culture medium: expansive vermiculite in a weight ratio of 10: 1, and to evaluate the sustained growth of bacteria in a sulfuric acid corrosion environment. It was immersed in a 5% solution of sulfuric acid according to JSTM C 7401. Samples of the surface of the coating material were taken 7 days after the immersion age, and this was reinoculated into the medium (passage) to confirm the formation of colonies, and the results are shown in FIG. 67.

Referring to FIG. 67, in the sample of the coating material incorporating Rhodoseudomonas palustris and Bacillus thuringiensis , a bacterial colony was not identified, and Rhodobacter capsulatus and Bacillus were confirmed. When samples of the coating material incorporating Bacillus subtilis can be observed, a relatively large bacterial colony formation can be observed , and Rhodobacter in terms of the sustained growth of slime-forming bacteria exposed to sulfuric acid corrosion environment capsulatus ) and Bacillus subtilis were found to be advantageous.

Experimental Example  4 (conjugated bacteria: Rhodobacter Capsule ( Rhodobacter capsulatus ), Utilization binder: magnesia-phosphate complex)

In the case of the above-mentioned loess based binder, α-half gypsum, blast furnace slag, fly ash and ordinary portland cement, it is difficult to fully implement the sustained growth of bacteria due to the rise in pH despite the use of the adsorbent due to the cement composition.

On the other hand, the magnesia-phosphate complex shows a neutral pH of pH 7-9, and the initial reaction rate is very fast, and condensation starts within 5 to 15 minutes of pouring, thereby achieving high initial strength expression rate. In addition, the adhesive strength of the magnesia-phosphate composite is higher than that of general cement, and when cement concrete is used as a base material, the adhesive strength is destroyed at the base material, not at the adhesive interface. In addition, the loss of adhesion strength according to the moisture state of the water surface is small (generally, the water surface is wet), and the effect of strength on the curing temperature is less. In addition, water and sewage repair work is carried out in winter, and the internal temperature is on the order of 0 ~ 5 ℃, and in the case of general cement concrete, the strength development is significantly slow in the low temperature environment. On the other hand, the magnesia-phosphate complex has no concern about deterioration due to the maintenance time since the strength expression is not significantly affected by the curing temperature. Therefore, in the present invention, it is assumed that the magnesia-phosphate composite will play a sufficient role as a binder of the coating material according to the present invention.

In this experimental example, Rhodobacter capsulatus ) magnesia-phosphate complex of various compositions (see Table 11 below) as a binder for the production of bacterial incorporation coating material in a weight ratio of 2: 1 (adsorbent-binding agent ratio 2) and the culture medium in which the adsorbent was immersed (adsorbent is A coating material was prepared in the same manner as in Experimental Example 1, except that the expanded vermiculite was used in a bacterial culture medium: expansive vermiculite weight ratio of 10: 1). The result of measuring pH is shown in FIG.

Referring to Figure 68, the phosphate content of the magnesia-phosphate composite is preferably 20 to 40% by weight, more preferably 30 to 40% by weight in order to achieve high compressive strength and pH retention performance of less than 10. In this case, considering the rapid initial reaction rate of the magnesia-phosphate complex, a retardant (Borax) is preferably added in an amount of 1 to 10 parts by weight, based on 100 parts by weight of the magnesia-phosphate complex, to a level of 3 to 5% by weight. It can be confirmed that it is more preferable to be added.

On the other hand, in order to determine the effect on the compressive strength and pH according to the type of phosphate using the four monophosphates and four diphosphates shown in Table 12, the experiment was conducted in the same manner as in Experiment 1, Compression strength and pH were measured and shown in FIG. 69.

Referring to FIG. 69, when the monophosphate was used rather than the diphosphate, the compressive strength and pH were excellent, and sodium phosphate (NaH ₂ PO ₄ ) or ammonium phosphate (NH ₄ H ₂ PO ₄ ) was the most used among the monophosphates. It can be seen that it is preferable.

Preferred embodiments of the present invention described above are disclosed to solve technical problems, and those skilled in the art to which the present invention pertains will be capable of various modifications, changes, additions, etc. within the spirit and scope of the present invention. Such changes, modifications and the like should be considered to be within the scope of the following claims.

* Explanation of the sign

110: opening and closing clip 120: adsorption pad

130: connecting rod 140: counterweight

150: opening and closing lid 160: screw opening

170: annular pin 210: concrete sphere

Claims (24)

A coating material comprising an adsorbent and a binder for adsorbing slime forming bacteria. The method of claim 1, The slime-forming bacteria are Rhodobacter capsulatus , Rhodobacter Rhodobacter blasticus , Rhodobacter sphaeroides , Rhodopseudomonas palustris , Rubrivivax gelatinosus , purple sulfur bacteria, green sulfur bacteria, Rhodoseudomonas palustris , Bacillus thuringiensis and Bacillus subtilis Coating material characterized in that at least one. The method of claim 1, The adsorbent is a coating material, characterized in that at least one selected from the group consisting of a high absorbent resin, a high porous resin, expanded vermiculite, pearlite and diatomaceous earth. The method of claim 1, The binder is an ocher-based binder, α-half gypsum, blast furnace slag, fly ash, a common portland cement and magnesia-phosphate coating material, characterized in that at least one member selected from the group consisting of. The method of claim 4, wherein The magnesia-phosphate binder is a coating material, characterized in that the phosphate content of 10 to 50% by weight. The method of claim 5, The phosphate may be potassium phosphate (KH ₂ PO ₄ ), calcium diphosphate (Ca (H ₂ PO ₄ ) ₂ ), sodium phosphate (NaH ₂ PO ₄ ), ammonium phosphate (NH ₄ H ₂ PO ₄ ), dipotassium phosphate ( K ₂ HPO ₄ ), calcium phosphate (CaHPO ₄ ), disodium phosphate (Na ₂ HPO ₄ ) and diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ) A coating material, characterized in that at least one selected from the group consisting of. The method of claim 5, The magnesia-phosphate binder further comprises 1 to 10 parts by weight of a retardant based on 100 parts by weight of the magnesia-phosphate composite. The method of claim 1, Coating material, characterized in that the silicon dioxide (SiO ₂ ) formed by the slime-forming bacteria has an internal structure to shield the pores. The method according to any one of claims 1 to 8, Coating material, characterized in that used to prevent the chemical erosion of the concrete structure surface. The method of claim 9, The concrete structure is a coating material, characterized in that the sewer pipe. The method of claim 9, The chemical erosion is a coating material, characterized in that by sulfuric acid. The method of claim 9, Coating material, characterized in that applied to the surface of the concrete structure in a thickness of 0.5 ~ 10mm. Culturing the slime forming bacteria to form slime; Adsorbing the slime-formed bacteria using an adsorbent to fix the slime-formed bacteria; And Mixing the bacteria adsorbed material with a binder; Coating material manufacturing method comprising a. The method of claim 13, The slime-forming bacteria are Rhodobacter capsulatus , Rhodobacter Rhodobacter blasticus , Rhodobacter sphaeroides , Rhodopseudomonas palustris , Rubrivivax gelatinosus ), purple sulfur bacteria (purple sulfur bacteria), green sulfur bacteria (green sulfur bacteria), Bacillus thuringiensis ( Bacillus thuringiensis ) and the method characterized in that at least one selected from the group consisting of Bacillus subtilis ( Bacillus subtilis ). . The method of claim 14, The Rhodobacter Rhodobacter capsulatus), Rhodobacter Blind stitch kusu (Rhodobacter blasticus), Rhodobacter sphaeroides (Rhodobacter sphaeroides ), Rhodopseudomonas palustris ), Rubrivivax gelatinosus , purple sulfur bacteria and green sulfur bacteria are 0.1 ~ 5g yeast extract based on 1 liter of purified water, disodium succinate hexa 1 to 50 g of hydrate (Disodium succinate hexahydrate), 0.1 to 5 ml of absolute ethanol, 0.1 to 5 ml of ferric citrate solution, 0.1 to 5 g of potassium dihydrogen phosphate (KH ₂ PO ₄ ), magnesium sulfate heptahydrate _{(MgSO 4 .7H 2 O) 0.1} ~ 5g, sodium chloride (NaCl) 0.1 ~ 5g, ammonium chloride (NH ₄ Cl) is 0.1 ~ 5g and salt hydrate (CaCl ₂ .2H ₂ O) containing a 0.01 ~ 0.5g Method characterized in that it was incubated in a medium pH 5-9 conditions. The method of claim 14, The Bacillus thuringiensis and Bacillus subtilis are 1-10 g of peptic digest of animal tissue, yeast extract 0.5-3 g, sodium chloride based on 1 l of purified water. (Sodium chloride) 1 to 10g and Beef extract (Beef extract) Method characterized in that it was incubated at a pH of 4 to 10 conditions in a medium containing. The method of claim 13, The carbon source used in the culture is characterized in that at least one selected from the group consisting of maltose (Maltose), dextrose (Dextrose) and fructose (Fructose). The method of claim 13, The adsorbent is characterized in that at least one member selected from the group consisting of high absorbent resin, high porous resin, expanded vermiculite, pearlite and diatomaceous earth. The method of claim 18, The amount of the slime-formed bacteria used in the adsorption to the adsorbent is 50 to 200 times when the adsorbent is the high absorbent resin or the high porous resin based on the weight of the bacterial culture medium, and the adsorbent is the expanded vermiculite, pearlite or diatomaceous earth. If the method, characterized in that 5 to 20 times. The method of claim 13, The adsorption is carried out including the step of immersing the adsorption pad in the culture medium of the bacteria after the adsorption material is put into the mesh-type adsorption pad having a mesh size of 100㎛ ~ 5mm and thickness 0.5 ~ 50mm. How to. The method of claim 20, The material of the adsorption pad is characterized in that the steel. The method of claim 20, The adsorption using the adsorbent is characterized in that the adsorption pad is introduced into the mesh-type adsorption pad, and the adsorption pad is suspended in the culture medium of the bacteria. The method of claim 20, The suction pad is suspended by a counterweight connected to the lower end of the suction pad, the weight of the counterweight is characterized in that determined by the following equation (1). [Equation 1]

(In Equation 1, d is the immersion depth of the adsorption pad, W _L is the loading load, W _S is the fixed load, L and B are the length and width of the adsorption pad, γ _w is the unit volume weight of the culture.) The method of claim 13, The amount of the binder used when mixing the adsorbent adsorbed with the bacteria and the binder is characterized in that 0.5 to 3 times the weight of the adsorbent adsorbed the bacteria.

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