Concrete repairing agent with bacterium-enzyme synergistic mineralization effect as well as preparation method and application of concrete repairing agent

Abstract

The invention discloses a concrete repairing agent with a bacterium-enzyme synergistic mineralization effect and a preparation method of the concrete repairing agent. The preparation method comprises the following steps: culturing urealytic bacteria to obtain a spore bacterium suspension, and mixing the spore bacterium suspension with a urease extracting solution to obtain a mixed solution; mixing the soluble calcium salt solution and the urea solution to obtain a cementing solution; the concrete repairing agent with the bacterium-enzyme synergistic mineralization effect is obtained after the mixed solution and the cementing solution are mixed, and the concrete repairing agent with the bacterium-enzyme synergistic mineralization effect is applied to crack repairing of concrete to generate multiple effects of regulating and controlling crystal forms and enhancing the crack filling compactness and the adhesion effect.

Description

Technical Field

[0001] The invention belongs to the technical field of biomineralization, and specifically relates to a bioremediation agent for repairing concrete microcracks by bacteria-enzyme synergistic mineralization, and a preparation method and application thereof. Background Art

[0002] At present, in order to improve the durability of concrete and prevent corrosive substances from penetrating into concrete, chemical materials such as epoxy resin, chlorinated rubber, wax, polyurethane, acrylic acid and siloxane can be used to treat cracks. However, materials used to repair crack structures, such as polymer plugging materials (such as epoxy resin) and water repellents (such as silane or siloxane), have some disadvantages, such as differences in thermal expansion coefficients that easily lead to interface peeling or the need for constant maintenance of repair materials due to gradual aging and degradation; in addition, construction repair processes such as high-pressure grouting may cause construction damage to the concrete surface, affect the structural stress of the concrete, and reduce the reliability of the concrete's service performance.

[0003] A microbial induced calcium carbonate deposition technology (MICP) that has emerged in recent years has made up for the limitations of the above-mentioned traditional repair methods or materials. It has achieved phased results in the fields of concrete crack repair and sand consolidation, and has aroused research attention in the fields of water and soil pollution control and cultural relics restoration.

[0004] Although MICP technology has been studied for repairing concrete cracks, the existing technology still has problems such as long repair cycle, low bonding strength and limited environmental adaptability of bacteria. One of the main reasons is that the volume yield of calcium carbonate induced by microorganisms per unit time is low, that is, the mineralization rate is low. The mineralized products formed after the single use of bacteria for repair are not as tight or dense as expected in the gaps inside the cracks; the mineralized products formed after the single use of free enzyme induced calcium carbonate deposition (EICP) for repair will have too much organic matter left, which is not good for the chemical stability of concrete. Therefore, whether it is a single bacteria or mixed bacteria or a single enzyme or a composite enzyme, in the actual application of repairing concrete cracks, the diversity of existing repair materials is insufficient, and the calcium carbonate crystals formed after repair cannot adapt to different crack conditions to the maximum extent, resulting in the problem of low repair efficiency.

[0005] In order to further improve the effect of MICP technology in repairing concrete cracks, it is urgent to provide a method of using bacteria and enzymes to synergistically mineralize to quickly repair concrete cracks. Summary of the invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0007] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0008] Therefore, an object of the present invention is to overcome the deficiencies in the prior art and provide a concrete repair agent with a bacteria-enzyme synergistic mineralization effect, a preparation method thereof, and an application thereof.

[0009] To solve the above technical problems, the present invention provides the following technical solution: A preparation method of a concrete repair agent with a bacteria-enzyme synergistic mineralization effect, characterized by comprising:

[0010] Culturing ureolytic bacteria to obtain a spore suspension, and mixing the spore suspension with a urease extract to obtain a mixed solution;

[0011] Mixing a soluble calcium salt solution and a urea solution to obtain a cementing solution;

[0012] Mixing the mixed solution with the cementing solution to obtain the biological repair agent for repairing concrete microcracks with a bacteria-enzyme synergistic mineralization effect.

[0013] As a preferred embodiment of the preparation method of the present invention, wherein: the ureolytic bacteria is Sporosarcina pasteuri.

[0014] As a preferred embodiment of the preparation method of the present invention, wherein: the urease extract is a crude urease extract extracted from soybeans.

[0015] As a preferred embodiment of the preparation method of the present invention, wherein: the concentration of the spore suspension obtained by culturing the ureolytic bacteria is 10 7 CFU / mL to 10 8 CFU / mL.

[0016] As a preferred embodiment of the preparation method of the present invention, wherein: the concentration of the urease extract is 0.1 - 100 U / mL.

[0017] As a preferred embodiment of the preparation method of the present invention, wherein: the volume ratio of the ureolytic bacteria to the urease extract before mixing is 3:1 to 1:3.

[0018] As a preferred embodiment of the preparation method of the present invention, wherein: in the cementing liquid, the urea solution and the soluble calcium salt solution are mixed at a volume ratio of 2:1 to 1:1, and the concentrations of urea and calcium ions are 0.5 to 2 mol / L.

[0019] As a preferred embodiment of the preparation method of the present invention, wherein: the volume ratio of the cementing liquid to the mixed liquid is 1:3 to 1:9.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide a concrete repair agent prepared by the above preparation method.

[0021] Another object of the present invention is to overcome the deficiencies in the prior art and provide the application of the concrete repair agent in the repair of concrete cracks.

[0022] Advantages of the present invention:

[0023] The present invention combines Microbially Induced Calcite Precipitation (MICP) and Enzyme-Induced Calcite Precipitation (EICP). Among them, the MICP technology is a biomineralization process that uses microbial metabolic activities to induce calcium carbonate precipitation. Its core is to use the metabolic activities of certain microorganisms (such as urea-decomposing bacteria) to change the chemical conditions of the local environment, thereby inducing the precipitation of calcium carbonate (CaCO3). This process mainly relies on microorganisms decomposing urea to produce carbonate ions (CO3 2- ) and combining with calcium ions (Ca 2+ ) in the environment to form calcium carbonate precipitation; while the EICP technology is a biomineralization process that directly uses free urease to catalyze the urea decomposition reaction and induces the precipitation of calcium carbonate (CaCO3). Different from the MICP technology, EICP does not rely on the metabolic activities of microorganisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0025] Figure 1 It is the mineral XRD pattern of the repaired concrete specimen in Example 1 of the present invention.

[0026] Figure 2SEM image of minerals on the repaired concrete specimen in Example 1 of the present invention.

[0027] Figure 3 EDS surface scan image of the repaired concrete specimen in Example 1 of the present invention.

[0028] Figure 4 Ca 2p spectrum of XPS of minerals on the repaired concrete specimen in Example 2 of the present invention. Detailed implementation manners

[0029] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the embodiments of the specification.

[0030] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0031] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0032] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available. Details are shown in Table 1.

[0033] Table 1

[0034] Name Commercial channels Article number Yeast extract Wuhan MLS Biological Technology Co., Ltd. LP0021B Ammonium sulfate Wuhan MLS Biological Technology Co., Ltd. 10002918 Sodium hydroxide Wuhan MLS Biological Technology Co., Ltd. 10019718 Manganese sulfate monohydrate Wuhan MLS Biological Technology Co., Ltd. 10034-96-5 Nickel chloride hexahydrate Wuhan MLS Biological Technology Co., Ltd. N814831 Urea Wuhan MLS Biological Technology Co., Ltd. 1152GR500 Anhydrous calcium chloride Wuhan MLS Biological Technology Co., Ltd. 10005861

[0035] Source of the strains used in the present invention: Sarcina pasteurii is from BNCC, and the preservation number is BNCC337394.

[0036] Example 1

[0037] (1) Mix the preserved Sarcina pasteurii bacterial solution with a liquid medium (containing 20 g / L of yeast extract, 10 g / L of ammonium sulfate, 1.4 g of sodium hydroxide, 0.012 g / L of manganese sulfate monohydrate, and 0.024 g / L of nickel chloride hexahydrate) that has been autoclaved at high temperature and pressure for 15 minutes in a ratio of 1:100, and place it at 30 °C and incubate it at a constant speed of 180 rpm for 22 h to obtain a bacterial solution with a urease-secreting function and a concentration of 10 8 CFU / mL that can be used for repairing concrete cracks.

[0038] (2) Extract a crude urease extract with a concentration of 1 U / mL from soybeans.

[0039] (3) Mix the bacterial solution and the enzyme solution, and stir slowly at a speed of 20 rpm for 3 h until evenly mixed to obtain a bacteria-enzyme mixture. Before mixing, the volume ratio of ureolytic bacteria to the urease extract is 3:1.

[0040] (4) Prepare a cementing solution using calcium chloride and urea, where the concentrations of calcium ions and urea are both 1 mol / L.

[0041] (5) Mix the bacteria-enzyme mixture and the cementing solution. The volume ratio of the bacteria-enzyme mixture to the cementing solution is 1:9 to obtain a concrete repair agent with bacteria-enzyme synergistic mineralization.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that in step (3), without changing the total amount, no urease extract is added, and the other steps are the same as in Example 1 to obtain a bacterial solution repair agent.

[0044] Comparative Example 2

[0045] The difference from Example 1 is that in step (3), without changing the total amount, no ureolytic bacteria are added, and the other steps are the same as in Example 1 to obtain an enzyme solution repair agent.

[0046] Characterize the repair effect of the specimens with completed crack healing in Example 1: Use SEM and XRD to analyze the mineral components and their morphologies attached to the specimens.

[0047] In this example, SEM and XRD are used to analyze the components and morphologies of the mineralization products attached inside the concrete cracks after repair. Among them, the crystal form of calcium carbonate is identified using Jade software, and the proportion of different crystal forms is calculated by the relative intensity method. The minerals on the concrete specimens repaired with the bio-repair agent with bacteria-enzyme synergistic mineralization are used as the experimental group, and the minerals on the concrete specimens repaired with the bacterial solution and the enzyme solution alone are used as the control group. The characterization of the repair effect is as follows Figures 1-3 .

[0048] It can be determined from Figures 1-3 that the mineralization product formed after repair is calcium carbonate crystal. As can be seen from Figure 1 , the calcium carbonate isomers formed after bacteria-enzyme synergistic repair have both vaterite crystal form and calcite crystal form. The combination of different types of calcium carbonate crystals can better improve the strength and durability of concrete. As can be seen from Figure 2 , the calcium carbonate crystal combination formed inside the concrete cracks after bacteria-enzyme synergistic repair is denser than that of using bacteria alone in Comparative Example 1, and the gaps between the crystals are smaller, which can better fill the inside of the concrete cracks. As can be seen from Figure 3It can be seen that the mineralization product of only using the enzyme in Comparative Example 2 has more N and C element distributions, that is, a higher organic matter content. Although the organic matter makes the calcium carbonate crystals formed in the concrete cracks filled more densely, a large amount of organic matter will be left in the formed mineral, which will damage the chemical stability of the concrete and lead to the deterioration of its structure. The mineralization product of the bacteria-enzyme synergistic action not only satisfies the dense filling but also ensures that the proportion of the organic components is not too high.

[0049] Example 2

[0050] (1) Mix the preserved Sporosarcina pasteurii bacterial liquid with the liquid medium treated by high-temperature and high-pressure sterilization for 15 minutes at a ratio of 1:150, and place it at 30 °C and incubate it at a constant temperature with a shaking speed of 200 rpm for 20 h to obtain a bacterial liquid with a urease-secreting function of 10 7 CFU / mL that can be used for repairing concrete cracks.

[0051] (2) Extract a crude urease extract with a concentration of 3 U / mL from soybeans.

[0052] (3) Mix the bacterial liquid and the enzyme liquid, and stir at a low speed of 20 rpm for 4 h until evenly mixed. The volume ratio of the ureolytic bacteria to the urease extract before mixing in the mixed liquid is 1:1 to obtain a bacteria-enzyme mixed liquid.

[0053] (4) Prepare a cementing liquid using calcium chloride and urea, where the concentrations of calcium ions and urea are both 1 mol / L.

[0054] (5) Mix the bacteria-enzyme mixed liquid and the cementing liquid, and the volume ratio of the bacteria-enzyme mixed liquid to the cementing liquid is 1:3.

[0055] Comparative Example 3

[0056] The difference from Example 2 is that in step (3), without changing the total amount, the urease extract is not added, and the other steps are the same as in Example 1 to obtain a bacterial liquid repair agent.

[0057] Comparative Example 4

[0058] The difference from Example 2 is that in step (3), without changing the total amount, the ureolytic bacteria are not added, and the other steps are the same as in Example 1 to obtain an enzyme liquid repair agent.

[0059] Characterize the repair effect of the specimens with completed crack healing in Example 2: Use XPS to analyze the organic components attached to the specimens and their mineralization mechanisms.

[0060] In this embodiment, XPS is used to analyze the microstructure of the mineralized products adhered to the concrete cracks after repair and the mineralization plugging mechanism. The minerals on the concrete specimens repaired with the bioremediation agent of the bacteria-enzyme synergistic mineralization are used as the experimental group, and the minerals on the concrete specimens repaired with the bacteria solution and the enzyme solution alone are used as the control group. The Ca 2p spectrum of the XPS results is subjected to peak fitting and area normalization, as shown in Figure 4 .

[0061] As can be seen from Figure 4 , in the calcium carbonate mineralized product generated by the bacteria-enzyme synergistic action, the electron binding energy of Ca has a significant right shift compared with that of the single use of bacteria for mineralization in Comparative Example 3, that is, the electron cloud of Ca expands, indicating that in the chemical environment of the product, the negatively charged organic components have an electrostatic attraction on the calcium in calcium carbonate, which shows that the enzyme in the bacteria-enzyme synergistic action fully participates in the process of mineral crystallization, which is very beneficial to improving the mechanical properties such as the toughness of the calcium carbonate mineralized product; compared with Comparative Example 4 where the enzyme is used alone for mineralization, the electron binding energy of the bacteria-enzyme synergistic mineralization method is equivalent, but it can reduce the weakening of the mechanical strength of the repair agent due to excessive residual organic matter when the enzyme is used alone.

[0062] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A preparation method of a concrete repair agent with bacteria-enzyme synergistic mineralization, characterized in that: including, culturing ureolytic bacteria to obtain a spore suspension, and mixing the spore suspension with a urease extract to obtain a mixed solution; mixing a soluble calcium salt solution and a urea solution to obtain a cementing solution; mixing the mixed solution with the cementing solution to obtain a concrete repair agent for repairing concrete microcracks by the synergistic mineralization of bacteria and enzymes.

2. The preparation method according to claim 1, characterized in that: The ureolytic bacteria is Sporosarcina pasteuri.

3. The preparation method according to claim 1, characterized in that: The urease extract is a crude urease extract extracted from soybeans.

4. The preparation method according to claim 2, wherein: The concentration of the spore suspension obtained by culturing the ureolytic bacteria is 10 7 CFU / mL to 10 8 CFU / mL.

5. The preparation method according to claim 3, characterized in that: The concentration of the urease extract is 0.1 - 100 U / mL.

6. The preparation method according to claim 4, characterized in that: The volume ratio of the ureolytic bacteria to the urease extract before mixing is 3:1 - 1:

3.

7. The preparation method according to claim 1, characterized in that: In the cementing solution, the urea solution and the soluble calcium salt solution are mixed at a volume ratio of 2:1 - 1:1, and the concentrations of urea and calcium ions are 0.5 - 2 mol / L.

8. The preparation method according to claim 7, characterized in that: The volume ratio of the cementing solution to the mixed solution is 1:3 - 1:

9.

9. A concrete repair agent prepared by the preparation method according to claims 1 - 8.

10. Use of the concrete repair agent according to claim 9 in the repair of concrete cracks.

Images