Low-shrinkage high-adhesion concrete crack repairing agent and preparation method thereof

Abstract

The invention provides a low-shrinkage high-adhesion concrete crack repairing agent and a preparation method thereof, and relates to the field of concrete crack repairing, the low-shrinkage high-adhesion concrete crack repairing agent comprises inorganic dry powder and a microbial liquid agent, the mass ratio of the inorganic dry powder to the microbial liquid agent is 100: (20-30); wherein the inorganic dry powder comprises 60-75 parts of active magnesium oxide, 9-16 parts of monopotassium phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash or silica fume and 5-15 parts of a boron compound; the microbial liquid agent is prepared from 10-25 parts of bacterial strain liquid, 1.2-3 parts of a nutrient source, 1.7-5 parts of a calcium source and 0-25 parts of distilled water; according to the invention, the induced mineralization ability of microorganisms is combined with the rapid hardening and early strength characteristics of an inorganic cementing material, so that the concrete crack repairing agent which has the characteristics of rapid plugging, high early strength, good cohesiveness, excellent environmental protection property and the like is developed.

Description

Technical Field

[0001] This invention relates to the field of concrete crack repair technology, and more specifically, to a low-shrinkage, high-adhesion concrete crack repair agent and its preparation method. Background Technology

[0002] Concrete, as a core material in construction, transportation, and water conservancy, is widely used in engineering structures such as buildings, bridges, tunnels, and dams. However, under construction, service environment, and external loads, concrete structures are highly susceptible to cracks of varying sizes. These cracks not only compromise the integrity and aesthetics of the concrete but also become channels for corrosive media such as moisture, chloride ions, and carbon dioxide to penetrate, accelerating steel corrosion and internal structural deterioration. This severely reduces the load-bearing capacity, durability, and service life of the concrete structure, and can even lead to structural safety hazards, causing significant economic losses and safety risks. Currently, a series of high-performance concrete crack repair materials have emerged, including inorganic, organic, organic-inorganic composite, and microbial types, significantly improving the mechanical properties and durability of crack repair. However, these repair materials still suffer from drawbacks such as poor adhesion, secondary cracking, and complex construction.

[0003] In the process of developing this invention, the applicant discovered that microbial remediation materials have become a research hotspot due to their environmental and sustainable advantages. Among them, urealytic bacteria produce urease with high activity and can form spores to resist harsh environments. However, when used alone, they are difficult to quickly meet the structural load-bearing requirements, and their interfacial bonding strength with the concrete matrix is ​​limited, further restricting the repair efficiency and scope. Inorganic remediation materials have the characteristics of fast setting speed, high early strength, and good compatibility with the concrete matrix, showing potential in the field of emergency repair. However, when used alone, they have defects such as large shrinkage rate and easy generation of microcracks, and lack continuous repair capabilities. They cannot cope with cracks caused by secondary cracking that may occur during the service of concrete, resulting in insufficient repair durability.

[0004] Therefore, how to reduce the shrinkage of concrete repair materials and improve their repair durability has become an urgent technical problem to be solved. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art, and discloses a low-shrinkage and high-adhesion concrete crack repair agent and its preparation method. The repair agent has the characteristics of rapid sealing, early high strength, good adhesion and excellent environmental protection.

[0006] The first aspect of this invention discloses a low-shrinkage, high-adhesion concrete crack repair agent, comprising: inorganic dry powder and microbial liquid, wherein the mass ratio of inorganic dry powder to microbial liquid is 100:(20~30); wherein the inorganic dry powder comprises 60-75 parts of active magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash or silica fume, and 5-15 parts of boron compound; the microbial liquid comprises 10-25 parts of bacterial inoculum, 1.2-3 parts of nutrient source, 1.7-5 parts of calcium source, and 0-25 parts of distilled water; the bacterial inoculum can maintain urease activity in the cement matrix and induce the formation of calcium carbonate.

[0007] The low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention preferably further includes: 0 to 3 parts of a colorant, wherein the colorant is an inorganic pigment, used to adjust the color of the repair agent to be consistent with the target area.

[0008] According to the low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention, preferably, the bacterial inoculum is a urealytic bacterial inoculum with a microbial concentration of 10. 8 -10 10 cells / ml.

[0009] According to the low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention, preferably, the urea-soluble bacterial inoculum is a urea-soluble bacterium with mineralization induction ability, including one or more of Bacillus pasteurellii, Bacillus subtilis, and Bacillus megaterium.

[0010] The low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention preferably uses one or more of urea, tryptone, beef extract, casein peptone, sodium chloride, and agar as its nutrient source.

[0011] In the low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention, preferably, the calcium source is one or more of calcium acetate, calcium lactate, and calcium nitrate.

[0012] The second aspect of the present invention also discloses a method for preparing a low-shrinkage, high-adhesion concrete crack repair agent, comprising: preparing raw materials according to the material ratio of the low-shrinkage, high-adhesion concrete crack repair agent provided by any of the above technical solutions, and processing them through the following steps: adding 100 parts of inorganic dry powder material, including magnesium oxide, potassium dihydrogen phosphate or ammonium dihydrogen phosphate, fly ash or silica fume, 0-3 parts of colorant, and boron compound, to a first container and mixing them evenly using a cement paste mixer; adding 20-30 parts of microbial liquid material, including bacterial inoculum, nutrient source, calcium source, and 0-25 parts of distilled water, to a second container and mixing them thoroughly; adding the microbial solution from the second container to the dry powder mixture in the first container and mixing them thoroughly using a cement paste mixer to obtain the finished repair agent.

[0013] The method for preparing the low-shrinkage, high-adhesion concrete crack repair agent disclosed in this invention preferably further includes: spraying a bacterial solution capable of generating calcium carbonate onto the concrete substrate to be repaired before using the finished repair agent; and applying the finished repair agent after the concrete substrate has formed a calcium carbonate network structure.

[0014] The beneficial effects of this invention include at least the following: This invention provides a bio-inorganic composite repair material that avoids the adverse effects of microbial repair materials failing to quickly meet structural load-bearing requirements and inorganic repair materials having large shrinkage rates and being prone to microcracks, thereby improving the repair effect of concrete cracks. Specifically: Inorganic dry powder, as a cementing material, provides microorganisms with a milder living environment different from traditional silicate cement, which is conducive to maintaining microbial activity; the use of composite nutrient sources and composite calcium sources improves the calcium carbonate precipitation effect, and the synergistic effect of fly ash / silica fume and boron compounds stabilizes the pH of the repair agent at 7-9, thereby extending the survival life of microorganisms and increasing the amount of calcium carbonate generated. In application, after a calcium carbonate structure with a high specific surface area and mutual cross-linking is formed on the concrete substrate, the crack repair agent is applied. Through the migration and mineralization of microorganisms in the interface area, the bonding performance between the old and new materials is enhanced. Attached Figure Description

[0015] Figure 1 The microstructure of the product formed in a concrete repair experiment using the low-shrinkage, high-adhesion concrete crack repair agent provided in Example 2 of the present invention is shown.

[0016] Figure 2 The diagram shows the shrinkage rate of the low-shrinkage, high-adhesion concrete crack repair agent of Examples 1-4 of the present invention in concrete repair experiments.

[0017] Figure 3 The diagram shows the tensile bond strength of the low-shrinkage, high-adhesion concrete crack repair agents of Examples 1-4 of the present invention in concrete repair experiments. Detailed Implementation

[0018] To better understand the above-described objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may be practiced in other ways different from those described herein, and therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] According to one embodiment of the present invention, a low-shrinkage, high-adhesion concrete crack repair agent is disclosed, comprising inorganic dry powder and microbial liquid, wherein the mass ratio of inorganic dry powder to microbial liquid is 100:(20~30); wherein the inorganic dry powder comprises 60-75 parts of active magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash or silica fume, and 5-15 parts of boron compound; the microbial liquid comprises 10-25 parts of bacterial inoculum, 1.2-3 parts of nutrient source, 1.7-5 parts of calcium source, and 0-25 parts of distilled water; the bacterial inoculum can maintain urease activity in the cement matrix and induce the formation of calcium carbonate.

[0020] According to the above embodiments, preferably, it further includes: 0 to 3 parts of a colorant, wherein the colorant is an inorganic pigment, used to adjust the color of the repair agent to be consistent with the target area.

[0021] According to the above embodiments, preferably, the bacterial inoculum is a urealytic bacterial inoculum with a microbial concentration of 10. 8 -10 10 cells / ml.

[0022] According to the above embodiments, preferably, the urea-degrading bacterial inoculum is a urea-degrading bacterium with the ability to induce mineralization, including one or more of Bacillus pasteurellii, Bacillus subtilis, and Bacillus megaterium.

[0023] According to the above embodiments, preferably, the nutrient source is one or more of urea, tryptone, beef extract, casein peptone, sodium chloride, and agar.

[0024] According to the above embodiments, preferably, the calcium source is one or more of calcium acetate, calcium lactate, and calcium nitrate.

[0025] like Figure 1 , Figure 2 and Figure 3 As shown, according to the low-shrinkage, high-adhesion concrete crack repair agent disclosed in the above embodiments, Examples 1-4 provide preparation methods for low-shrinkage, high-adhesion concrete crack repair agents with different material ratios, and four finished repair agent products were prepared. Concrete repair experiments were conducted using the finished repair agent products.

[0026] Example 1 In this embodiment, distilled water is used instead of microbial liquid agent. 100 parts of inorganic dry powder, including 60-75 parts of magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash / silica fume, 3 parts of colorant, and 5-15 parts of boron compound, are added to the first container and mixed evenly using a cement paste mixer. Add 25 parts of solution to the second container, including 0 parts of bacterial inoculum, 0 parts of nutrient source, 0 parts of calcium source, and 25 parts of distilled water, and stir it thoroughly with a glass rod; Finally, use a cement paste mixer to mix the materials prepared in the two containers evenly to obtain the finished repair agent. Spray or apply it to the concrete cracks to complete the repair.

[0027] The repaired concrete sample was cured at room temperature. The basic properties of concrete crack repair agents were tested using the shrinkage test and tensile bond strength test methods in the standard "Standard for Test Methods of Basic Properties of Building Mortar JGJ / T 70-2009". The experimental results are as follows: Figure 2 and Figure 3 As shown, the shrinkage rate after 28 days was 6.9 × 10⁻⁶. -4 The 3d tensile bond strength is 0.59 MPa.

[0028] Example 2 Add 100 parts of inorganic dry powder to the first container, including 60-75 parts of magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash / silica fume, 3 parts of colorant, and 5-15 parts of boron compound, and mix evenly using a cement paste mixer. Add 25 parts of solution to the second container, including 10 parts of bacterial inoculum, 1.2 parts of nutrient source, 1.7 parts of calcium source, and 15 parts of distilled water, and stir it thoroughly with a glass rod. Finally, use a cement paste mixer to mix the materials prepared in the two containers evenly to obtain the finished repair agent. Spray or apply it to the concrete cracks to complete the repair.

[0029] The repaired concrete sample was cured at room temperature.

[0030] The basic properties of concrete crack repair agents were tested using the shrinkage test and tensile bond strength test methods in the standard "Standard for Test Methods of Basic Properties of Building Mortar JGJ / T 70-2009". The experimental results are as follows: Figure 2 and Figure 3 As shown, the shrinkage rate after 28 days was 6.3 × 10⁻⁶. -4 The 3d tensile bond strength is 0.82 MPa.

[0031] like Figure 1 As shown, the microstructure of the hydration products of the repair agent was observed using a scanning electron microscope, revealing spherical calcite-type calcium carbonate crystals that bonded together to form a porous aggregate structure.

[0032] Example 3 Add 100 parts of inorganic dry powder to the first container, including 60-75 parts of magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash / silica fume, 3 parts of colorant, and 5-15 parts of boron compound, and mix evenly using a cement paste mixer. Add 25 parts of solution to the second container, including 17.5 parts of bacterial inoculum, 2.1 parts of nutrient source, 3 parts of calcium source, and 7.5 parts of distilled water, and stir it thoroughly with a glass rod. Finally, use a cement paste mixer to mix the materials prepared in the two containers evenly to obtain the finished repair agent. Spray or apply it to the concrete cracks to complete the repair.

[0033] The repaired concrete sample was cured at room temperature.

[0034] The basic properties of concrete crack repair agents were tested using the shrinkage test and tensile bond strength test methods in the standard "Standard for Test Methods of Basic Properties of Building Mortar" (JGJ / T 70-2009). The results are as follows: Figure 2 and Figure 3 As shown, the shrinkage rate after 28 days was 6.1 × 10⁻⁶. -4 The 3d tensile bond strength is 0.32 MPa.

[0035] Example 4 Add 100 parts of inorganic dry powder to the first container, including 60-75 parts of magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash / silica fume, 3 parts of colorant, and 5-15 parts of boron compound, and mix evenly using a cement paste mixer. Add 25 parts of solution to the second container, including 25 parts of bacterial inoculum, 3 parts of compound nutrients, 4.5 parts of compound calcium source, and 0 parts of distilled water, and stir it thoroughly with a glass rod. Finally, use a cement paste mixer to mix the materials prepared in the two containers evenly to obtain the finished repair agent. Spray or apply it to the concrete cracks to complete the repair.

[0036] The repaired concrete sample was cured at room temperature.

[0037] The basic properties of concrete crack repair agents were tested using the shrinkage test and tensile bond strength test methods in the standard "Standard for Test Methods of Basic Properties of Building Mortar" (JGJ / T 70-2009). The results are as follows: Figure 2 and Figure 3 As shown, the shrinkage rate after 28 days was 5.9 × 10⁻⁶. -4 The 3d tensile bond strength is 0.2 MPa.

[0038] In summary, the embodiments 1-4 of this invention, by testing the shrinkage rate and tensile bond strength of the concrete crack repair agent under different microbial dosages, clarified the basic properties of the concrete crack repair agent. Combined with its repair effect, this provides theoretical support for the application of the concrete crack repair agent. This invention uses a bio-inorganic composite repair material, avoiding the disadvantages of microbial repair materials failing to quickly meet structural load-bearing requirements and inorganic repair materials having a large shrinkage rate and being prone to microcracks, thereby improving the concrete crack repair effect.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-shrinkage, high-adhesion concrete crack repair agent, characterized in that, include: The mixture comprises inorganic dry powder and microbial liquid, wherein the mass ratio of the inorganic dry powder to the microbial liquid is 100:(20~30); wherein the inorganic dry powder comprises 60-75 parts of active magnesium oxide, 9-16 parts of potassium dihydrogen phosphate or ammonium dihydrogen phosphate, 10-20 parts of fly ash or silica fume, and 5-15 parts of boron compound; the microbial liquid comprises 10-25 parts of bacterial inoculum, 1.2-3 parts of nutrient source, 1.7-5 parts of calcium source, and 0-25 parts of distilled water; the bacterial inoculum can maintain urease activity and induce the formation of calcium carbonate in the cement matrix.

2. The low-shrinkage, high-adhesion concrete crack repair agent according to claim 1, characterized in that, Also includes: 0 to 3 parts of colorant, wherein the colorant is an inorganic pigment, used to adjust the color of the repair agent to match the target area.

3. The low-shrinkage, high-adhesion concrete crack repair agent according to claim 1, characterized in that, The bacterial inoculum is a urealytic type inoculum with a microbial concentration of 10. 8 -10 10 cells / ml.

4. The low-shrinkage, high-adhesion concrete crack repair agent according to claim 3, characterized in that, The urea-degrading bacterial inoculum is a urea-degrading bacterium with the ability to induce mineralization, including one or more of Bacillus pasteurellii, Bacillus subtilis, and Bacillus megaterium.

5. The low-shrinkage, high-adhesion concrete crack repair agent according to claim 1, characterized in that, The nutrient source is one or more of the following: urea, tryptone, beef extract, casein peptone, sodium chloride, and agar.

6. The low-shrinkage, high-adhesion concrete crack repair agent according to claim 1, characterized in that, The calcium source is one or more of calcium acetate, calcium lactate, and calcium nitrate.

7. A method for preparing a low-shrinkage, high-adhesion concrete crack repair agent, characterized in that, include: Raw materials are prepared according to the material ratio of the low-shrinkage, high-adhesion concrete crack repair agent as described in any one of claims 1 to 6, and processed through the following steps: Add 100 parts of inorganic dry powder material to the first container, including magnesium oxide, potassium dihydrogen phosphate or ammonium dihydrogen phosphate, fly ash or silica fume, 0-3 parts of colorant, and boron compound, and mix evenly using a cement paste mixer. Add 20-30 parts of microbial liquid material, including bacterial inoculum, nutrient source, calcium source, and 0-25 parts of distilled water, to the second container and stir thoroughly; The microbial solution in the second container is added to the dry powder mixture in the first container and thoroughly mixed using a cement paste mixer to obtain the finished repair agent.

8. The method for preparing the low-shrinkage, high-adhesion concrete crack repair agent according to claim 7, characterized in that, Also includes: Before using the finished repair agent, a bacterial solution that generates calcium carbonate is sprayed onto the concrete substrate to be repaired. After the calcium carbonate network structure has formed on the concrete substrate, the finished repair agent is then applied.

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