WO2022102882A1 - Cross section repair material based on halophilic slime-forming bacteria - Google Patents

Abstract

Disclosed is a novel ecological salt damage-resistant repair material for repairing concrete structures that have been exposed to an environment of chemical degradation due to salt damage (Cl-) in a marine environment, wherein the repair material excludes existing organic materials. The present invention provides a material for repairing a concrete cross section in a salt damage environment, the concrete cross section repair material comprising a mixture of a salt damage resistant repair material and a carrier, wherein the salt damage resistant repair material comprises a binder, including ordinary type 1 Portland cement and an EVA-based polymer, polyethylene fibers, and fine aggregate, and the carrier has a porous structure on which bacteria for breaking down chlorine ions and halophilic slime-forming bacteria are fixed.

Description

Basophil slime-forming bacteria-based single-sided repair material

The present invention relates to a concrete cross-section repair material, and more particularly, to a bacteria-based cross-section repair material.

This application claims priority to Korean Patent Application No. 10-2020-0150193, filed on November 11, 2020, the contents of which are incorporated herein by reference.

The present invention is derived from the research conducted by the research fund support of the Ministry of Land, Infrastructure and Transport Construction Technology Research Project.

[Project unique number: 2015897601, Research project name: Development of salt-resistant ecological coating material based on halophilic bacteria slime]

Concrete structures exposed to salt environment may have a sharp decrease in their durability due to deterioration of concrete and corrosion of reinforcing bars. In particular, ship anchoring facilities, breakwaters, and offshore plants require rapid construction and fast hardening of repair/reinforcement work in response to salt damage.

Organic materials (paints) such as epoxy, vinyl ester, and acrylic rubber used as materials for the repair of marine structures that are deteriorated by salt damage have excellent adhesive strength with the initial concrete structure, but thermal expansion coefficient, drying, and shrinkage In the long run, the elastic film is peeled off at the interface with the concrete structure because the deformation characteristics caused by such factors are different from that of concrete. In addition, if a perfect surface treatment is not performed on the surface of the concrete matrix, which is the surface to be repaired, the adhesive strength with the concrete will decrease rapidly, and the adhesive strength will change rapidly depending on the moisture state of the underlying concrete.

In particular, in the case of marine structures to be repaired, it is practically impossible to cleanly remove fouling that is inevitably caused by contaminants and marine organisms present in seawater. can be easily removed and peeled off. In addition, in the case of organic materials, it is difficult to construct because the coating film is applied in three stages: top coat, middle coat, and undercoat using paints with different performance as a form of paint. , it greatly affects the overall performance and is very unfavorable to securing long-term durability. At the same time, organic coating materials contain a large amount of environmental pollution and harmful substances, so raw materials and manufacturing processes are strictly regulated worldwide. It causes material cost increase and construction cost increase due to the use of advanced technology materials.

In the case of marine structure repair using inorganic materials, unlike organic materials, it is advantageous in terms of securing integrity with the marine concrete structure, which is the structure to be repaired. is still constantly exposed to the degradation environment caused by salt damage. In addition, since the use of materials for imparting the functionality of improving deterioration resistance in the existing inorganic materials for salt damage repair is rather limited, economic loss due to frequent re-construction increases.

[Prior Patent Literature]

- Korea Registered Patent No. 1779935 (2017.09.13.)

- Korean Patent No. 1355392 (2014.01.20.)

An object of the present invention is to provide a new concept ecological salt damage resistance repair material that excludes existing organic materials as a material for repairing concrete structures exposed to chemical degradation due to salt damage (Cl ^- ) in a marine environment.

In order to solve the above problems, the present invention provides a salt damage-resistant repair material comprising a binder comprising a type 1 ordinary Portland cement and an EVA-based polymer, polyethylene fibers and fine aggregate; and a porous structure in which chlorine ion-decomposing bacteria and salt slime-forming bacteria are fixed. of the carrier; provides a concrete cross-section repair material in a mixed salt environment.

In addition, the salt damage resistance repair material contains 90 to 95 weight % of the type 1 ordinary Portland cement, 5 to 10 weight % of the EVA-based polymer, and 0.1 to 0.3 parts by volume of the polyethylene fiber based on 100 parts by volume of the repair material, The fine aggregate is silica sand having an average particle diameter of 0.25 to 0.7 mm, a fine aggregate-binder ratio (S/B) of 1.8 to 2.2 by weight, and a water-binder ratio (W/B) of 28 It provides a concrete cross-section repair material in a salt environment, characterized in that to 35% by weight.

In addition, the carrier is expanded vermiculite, and provides a concrete cross-section repair material in a salty environment, characterized in that the chlorine ion-decomposing bacteria and salt slime-forming bacteria are fixed under negative pressure conditions.

In addition, the chlorine ion-decomposing bacteria are Halomonas venusta , and the basophil slime-forming bacteria are Sulfitobacter mediterraneus .

According to the present invention, it is an ecological salt damage resistance repair material based on salt strains that decompose chlorine ions in slimes and chloride compounds that have the function of protecting concrete from salt damage in a marine environment, exposed to chemical deterioration environment due to salt damage (Cl ^- ) It is possible to provide a material having a function of controlling deterioration due to concrete salt damage for the repair of an old concrete structure.

From this, the repair and durability of marine concrete structures and reinforced concrete structures are improved, the maintenance efficiency of structures is improved by the ecological salt damage deterioration protection effect of salt slime-forming bacteria, and the maintenance process such as water absorption inhibitor and primer application is omitted. It has the effect of reducing the construction cost and shortening the construction period.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, similar reference numerals are given to similar parts throughout the specification, and the detailed configuration direction of the present invention will be described with reference to the drawings. Also, throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

The present invention is a material having a function of controlling deterioration due to concrete salt damage for repair of a concrete structure exposed to a chemical deterioration environment of salt damage, and a cross section of concrete in a salt damage environment comprising a salt damage resistant repair material and a carrier of a porous structure in which bacteria are fixed Start repair materials.

The salt damage-resistant repair material (called 'Herb-con C') is a mixture developed in consideration of bacterial growth and adhesive strength, and a binder containing type 1 ordinary Portland cement and an EVA (Ethylene Vinyl Acetate)-based polymer, polyethylene Includes fibers and fine aggregates.

The binder composition is preferably 90 to 95% by weight of the type 1 ordinary Portland cement and 5 to 10% by weight of the EVA-based polymer, and in this case, it was confirmed that the implementation of the deterioration control function due to concrete salt damage was the most excellent.

In addition, the polyethylene fiber is a component added to impart strength and rigidity reinforcement to the salt damage resistance repair material, and a polyethylene fiber material having an average diameter of 50 to 200 μm, preferably 100 to 150 μm may be used.

The content of the polyethylene fiber is preferably 0.1 to 0.3 parts by volume based on 100 parts by volume of the repair material, and in this case, it was confirmed that the strength and rigidity strengthening function of the repair material was the most excellent while the deterioration control function due to concrete salt damage was improved.

It is preferable to use silica sand having an average particle diameter of 0.25 to 0.7 mm as the fine aggregate, and the fine aggregate content is such that the sand to binder ratio (S/B) is 1.8 to 2.2 by weight due to concrete salt damage. It was confirmed to be desirable when considering the implementation of the deterioration control function. At this time, the water-binder ratio (W/B) is preferably 28 to 35% by weight.

In the present invention, bacteria that can effectively implement the function of protecting concrete from salt damage in a marine environment by mixing with the water-retaining material as salty strains having the ability to decompose chlorine ions in chlorine compounds were selected.

The mechanism of deterioration due to salt damage of concrete is that as chlorine ions penetrate and diffuse into the concrete, chlorine ions (Cl ^- ) combine with Ca(OH) ₂ , the cement hydrate of concrete exposed to seawater, to form CaCl ₂ . ₂ is a soluble porous compound that dissolves in seawater and increases the porosity of concrete, causing a decrease in durability (chlorination corrosion). The CaCl ₂ compound formed by chlorine ions in seawater reacts with monosulfate again and is combined into Friedel salt and chloroferrite hydrate. , which in turn accelerates the formation of CaCl ₂ compounds, forming a vicious cycle of salt erosion mechanism. In addition, when chloride ions in the pores of concrete increase, reinforcing bars combine with chloride to form FeCl ₂ , which reacts with water to become an active environment for corrosion. Corrosion of reinforcing bars causes volume expansion, which causes expansion and exfoliation of cracks in concrete, which greatly affects durability reduction.

In the present invention, as a result of confirming whether it is possible to effectively implement the function of controlling deterioration due to salt damage to the various basophils (marine microorganisms) shown in Table 1 below, Halomonas, an anaerobic basophil having a chlorine ion decomposition ability, Halomonas venusta ) grows in a marine environment and releases yeast capable of decomposing chlorine ions, confirming that it has the best function to consume Cl compounds (CaCl ₂ and FeCl ₂ ), which are factors that cause salt degradation and durability degradation of concrete.

strain	Species
MH60115	Sulfitobacter mediterraneus
HY72501	Bacillus licheniformis
1GJ1_9	Tenacibaculum litoreum
G2M2_14	Phaeobacter italicus
1GJ1_2	Erythrobacter flavus
1GJ1_1	Kordiimonas gwangyangensis
3-561	Halomonas venusta

The separation process for the strains is as follows.

(1) Sample collection

Seawater and mussels were collected from Wando Port in Gunnae-ri, Wando-eup, Wando-gun, Jeollanam-do, and the collected samples were stored in an icebox and transported.

(2) Microbial isolation and culture conditions

The collected mussel shells and mussel flesh were vortexed to remove microorganisms. After collecting the microorganisms desorbed from seawater and mussels on filter paper through filtration, vortex to desorb the microorganisms from the filter paper, and then serially diluted to 10 ^-4 with 3.5% NaCl solution and medium (50% marine + 50% R2A agar (3.5% NaCl) ) at pH 7.6) and incubated for 1 week under aerobic conditions at 30°C. The colonies that appeared after culturing were purified and cultured according to their characteristic types. As a result of separation and identification of each cultured microorganism by 16S rDNA sequencing, it was confirmed that each cultured microorganism was a known microorganism in Table 1.

In addition, in the present invention, bacteria that can effectively implement basophil slime formation on the concrete surface were selected.

In the present invention, as a result of confirming whether it is possible to effectively implement basophilic slime formation under conditions similar to the marine environment for the various basophilic strains shown in Table 1 above, it was established as a basophil capable of growing in seawater having a salinity concentration of 3 to 5 wt%. Sulfitobacter mediterraneus forms a slime film on the concrete surface through growth and proliferation in the corresponding environment and has the best function as a barrier to resist the penetration and diffusion of chlorine ions in the concrete structure. Confirmed.

The slime film formed by the bacteria forms a barrier film against the penetration and diffusion of chlorine ions on the concrete surface, thereby inhibiting the formation of CaCl ₂ compounds and FeCl ₂ compounds, which have an effect of increasing voids and lowering durability in the concrete.

In the present invention, the chlorine ion-decomposing bacteria and salt slime-forming bacteria are fixed to a porous carrier (referred to as 'Healing ⁺ C').

Chloride ion-decomposing bacteria and salt slime-forming bacteria-based carriers containing bacteria discovered for repair and durability improvement of salt-damaged concrete and culture medium for their growth are inoculated into a medium containing yeast extract, ferric citrate, etc. 5 To 50 ℃, preferably 30 to 40 ℃ in an incubator at a concentration of 10 ⁸ to 10 ¹⁰ cells / ㎖ chlorine-decomposable basophils and slime-forming bacteria culture solution is fixed to a material having a porous structure of countless pores. As such, in the present invention, it was confirmed that expanded vermiculite was most suitable considering the function of protecting concrete from salt damage in the marine environment.

Here, the effective medium composition (Distilled water up to 1 ℓ standard) for the growth and proliferation of Halomonas venusta as the chlorine ion-decomposing bacteria and Sulfitobacter mediterraneus as the basophil slime forming bacteria is peptone 3 to 7 g, Yeast extract 0.5 to 1.5 g, Ferric citrate 0.05 to 0.2 g, Sodium chloride 17 to 23 g, Magnesium chloride 3 to 9 g, Magnesium sulfate 2 to 5 g, Calcium chloride 1 to 3 g, Pottasium chloride 0.3 to 1 g, Sodium biarbonate 0.1 to 0.5 g, Potassium bromide 0.05 to 0.15 g, Strontium chloride 20 to 50 mg, Boric acid 15 to 30 mg, Sodium silicate 2 to 6 mg, Sodium fluoride 1 to 5 mg, Ammonium nitrate 1 to 5 mg, Disodium phosphate may be 5 to 15 mg.

In the expanded vermiculite, the bacteria and its medium used for protection against salt damage and degradation self-grow and multiply on the surface of a concrete structure exposed to a salt degradation environment (marine environment), and act as a protector against deterioration and erosion of concrete. The fixation of the bacterial culture solution to the immobilization material can be accomplished through adsorption in a sterile negative pressure container at 10 to 30 torr, 10 to 60 minutes, and the expanded vermiculite, which has been immobilized in the bacterial culture, absorbs not only bacterial cells but also a large amount of moisture and medium nutrients. will include

Mixing of the above salt damage-resistant repair material and the concrete cross-section repair material using the carrier of the porous structure in which the bacteria is fixed can be presented in various ways depending on the amount of the bacteria-based carrier added. It is preferably 35%. Table 2 below exemplarily shows the required amount of salt damage resistant repair material and bacteria-based carrier by thickness when constructing 1 m2 of ecological salt damage resistant concrete cross-section repair material.

division (repair thickness)	Salt damage resistant repair material material requirements	Bacterial-based carrier material requirements	Bacterial-based carrier mixing ratio
T=10mm	13 kg/m2	0.4 kg/m2	Mix 10% of the total volume of salt damage resistant repair material
T=20mm	26 kg/m2	0.8 kg/m2
T=30mm	39 kg/m2	1.2 kg/m2
T=40mm	52 kg/m2	1.6 kg/m2
T=50mm	65 kg/m2	2.0 kg/㎡
division (repair thickness)	Salt damage resistant repair material material requirements	Bacterial-based carrier material requirements	Bacterial-based carrier mixing ratio
T=10mm	12 kg/m2	0.8 kg/m2	Mix 20% of the total volume of salt damage resistant repair material
T=20mm	24 kg/m2	1.6 kg/m2
T=30mm	36 kg/m2	2.4 kg/㎡
T=40mm	48 kg/m2	3.2 kg/㎡
T=50mm	60 kg/㎡	4.0 kg/m2
division (repair thickness)	Salt damage resistant repair material material requirements	Bacterial-based carrier material requirements	Bacterial-based carrier mixing ratio
T=10mm	10 kg/m2	1.4 kg/㎡	35% of the total volume of the salt damage resistant repair material is mixed
T=20mm	21 kg/m2	2.8 kg/㎡
T=30mm	32 kg/m2	4.2 kg/㎡
T=40mm	42 kg/m2	5.6 kg/m2
T=50mm	53 kg/m2	7.0 kg/㎡

Table 2 above shows the required amount of salt damage resistant repair material and halophilic bacteria-based carrier by thickness when constructing ecological salt damage resistant concrete cross-section repair materials regardless of the construction method to be described later, and the construction thickness (T) can be presented as 10 to 50 mm In addition, depending on the mixing ratio of the bacteria-based carrier, the salt damage resistant repair material may be 10 to 65 kg/m2, and the basophilic bacteria-based carrier may be 0.4 to 7.0 kg/m2.

The construction of the ecological salt damage resistance concrete cross-section repair material can be constructed by mechanical spray pouring, and will be described below by way of example. When mixing the ingredients, mix for 3 to 5 minutes so that they can be mixed evenly using a mixer or hand mixer. In the first step of spraying, a thin spray of 5 mm is applied to remove voids on the substrate and to increase adhesion. 2nd stage spray should be within 90% of the design thickness including the 1st stage thickness. When flattening the surface after spraying, pay attention to the connection construction part or the connection part with the underlying surface.

Hereinafter, specific examples according to the present invention will be described.

Example

Prepare a binder with a composition of 1st class ordinary Portland cement of 92% by weight and EVA-based polymer 8% by weight, and prepare polyethylene fibers (average diameter of 120 μm) to 0.2 parts by volume based on 100 parts by volume of the total repair material, and silica sand ( The average particle diameter is 0.25 to 0.7 mm), the fine aggregate-binder ratio (S/B) is 2 weight ratio, and the water-binder ratio (W/B) is 28 to 35 weight% By mixing as much as possible, a salt damage resistant repair material was prepared.

In addition, Halomonas venusta as a chlorine ion-decomposing bacterium and Sulfitobacter mediterraneus as a basophil slime-forming bacterium were inoculated into the medium of the composition of Table 3 below with the same content and then inoculated in an incubator (30 to 40 ° C.) ) to a concentration of 10 ⁹ cells/ml and cultured for 7 days. Thereafter, the bacterial culture solution is put into an internally stirred sterile negative pressure container, the expanded vermiculite in an amount of 10 parts by weight based on 100 parts by weight of the bacterial culture solution is immersed in the culture solution, the door is closed, and the valve is set to a negative pressure environment of 10 to 30 torr. was adjusted, and adsorption was carried out for 30 minutes, after which the expanded vermiculite on which the bacteria was immobilized was recovered.

Thereafter, the final concrete cross-section repair material was prepared by mixing expanded vermiculite in which bacteria were fixed in a mixing ratio of 20% to the aggregate volume of the prepared salt damage-resistant repair material with a mixer.

Source	Amount
Peptone	5.0 g
yeast extract	1.0 g
Ferric citrate	0.1 g
sodium chloride	19.45 g
Magnesium chloride	5.9 g
Magnesium sulfate	3.24 g
Calcium chloride	1.8 g
Pottasium chloride	0.55 g
Sodium biarbonate	0.16 g
Potassium bromide	0.08 g
Strontium chloride	34.0 mg
Boric acid	22.0 mg
sodium silicate	4.0 mg
Sodium fluoride	2.4 mg
Ammonium nitrate	1.6 mg
Disodium phosphate	8.0 mg
Distilled water up to 1 liter

test example

Performance evaluation was performed according to various test standards for the prepared concrete cross-section repair material, and the results are shown in Table 4 below.

Test Items	Adhesive strength (N/㎟) : Standard		Compressive strength (N/㎟)	Neutralization resistance (mm)	pitch (g)		water absorption coefficient (kg/(㎡·h 0.5 )	length change rate (%)
	28 days		28 days
standard	1.0 or higher		20.0 or higher	within 2	20.0 or less		0.5 or less	Within ±0.15
result	2.1		48.2	0	6.5		0.22	- 0.02
Test Methods	KS F 4042 : 2012
Test Items		Chloride diffusion coefficient (×10 -12 m2/s)				Passing Charge (Coulombs)
		28 days				28 days
general repair material		7.2				590
Ecological salt damage resistant repair material		0.6				130
Test Methods		NT BUILD 492				KS F 2711

Referring to Table 4, the ecological salt damage-resistant concrete cross-section repair material according to the present invention is 2.1 compared to the required performance of adhesive strength (1.0 MPa or more) and compressive strength (20 MPa) presented in KS F 4042 (polymer cement mortar). appeared more than twice as high. In addition, the neutralization depth was 0 mm and the length change rate was 0.04%, which satisfies the quality standards required by KS F 4042. In addition, in the evaluation result of the chloride diffusion coefficient according to NT BUILD 492, the ecological salt damage resistant concrete section repair material according to the present invention is at a level that is 90% lower than that of the general repair material, and the total through-current according to KS F 2711 is 88% compared to the general repair material It showed remarkably excellent results in all evaluation items at a low level.

Preferred embodiments of the present invention described above are disclosed to solve the technical problem, and various modifications, changes, additions, etc. will be possible within the spirit and scope of the present invention by those of ordinary skill in the art to which the present invention pertains. , such modifications and changes should be regarded as belonging to the following claims.

Claims (4)

A salt damage resistant repair material containing a binder containing type 1 ordinary Portland cement and EVA polymer, polyethylene fibers and fine aggregate; and a porous structure carrier in which chlorine ion decomposing bacteria and salt slime forming bacteria are fixed; in a mixed salt environment Concrete section repair material.

The method of claim 1,

The salt damage resistance repair material contains 90 to 95 weight % of the first-class ordinary Portland cement, 5 to 10 weight % of the EVA-based polymer, and 0.1 to 0.3 parts by volume of the polyethylene fiber based on 100 parts by volume of the repair material,

The fine aggregate is silica sand having an average particle diameter of 0.25 to 0.7 mm, and a fine aggregate-binder ratio (S/B) is 1.8 to 2.2 by weight,

Concrete cross-section repair material in a salt damage environment, characterized in that the water-binder ratio (W/B) is 28 to 35% by weight.

According to claim 1,

The carrier is expanded vermiculite, and the chlorine ion decomposing bacteria and salt slime forming bacteria are fixed under negative pressure conditions.

According to claim 1,

The chlorine ion-decomposing bacteria is Halomonas venusta ( Halomonas venusta ), and the basophil slime-forming bacteria are Sulfitobacter mediterraneus ) Concrete cross-section repair material in a salty environment, characterized in that it is.