A concrete micro-crack fog vaporization repair material and a repair method

Abstract

The present application relates to the technical field of concrete crack repair, in particular to a concrete micro-crack fog vaporization repair material and its preparation and use method. The concrete micro-crack fog vaporization repair material comprises A liquid, B liquid and C powder. The concrete micro-crack fog vaporization repair method comprises the following steps: tightly attaching the sealing cover of the fog vaporization device and the air extraction cover of the air extraction device to the two ends of the concrete crack respectively; applying sealing paint to the concrete crack not covered by the sealing cover or the air extraction cover; fog vaporization treatment is performed on the A liquid, B liquid and C powder of the concrete micro-crack fog vaporization repair material by using the fog vaporization device, and air extraction treatment is performed by using the air extraction device, so that the micro-droplets or aerosols obtained by the fog vaporization treatment fully cover the section of the concrete crack due to the pressure difference and convection. The present application can effectively improve the penetration depth of the slurry, uniformly distribute in the form of micro-droplets or aerosols, and ensure that the repair liquid fully covers the inside of the crack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete crack repair, in particular to a concrete micro-crack fog vaporization repair material and its preparation and use method. BACKGROUND

[0002] During long-term use, concrete often produces cracks due to temperature changes, load effects or other factors. If these cracks are not repaired in time, external factors such as water and chemicals will penetrate, causing further damage to the concrete, and even affecting the stability of the structure.

[0003] Currently, traditional concrete crack repair methods rely on liquid injection or cementitious material injection, but these methods have certain limitations in terms of penetration depth and reaction uniformity, especially for micro-cracks with an opening less than 0.3mm, it is difficult to ensure comprehensive repair of the deep part of the crack.

[0004] Microbial-induced calcium carbonate precipitation (MICP) repair technology is a new method for repairing concrete cracks, which repairs cracks by producing calcium carbonate precipitation through the metabolic activity of microorganisms. However, this technology also faces the problem of insufficient slurry penetration depth and distribution uniformity in practical application.

[0005] Therefore, how to optimize the injection and distribution of slurry, especially how to effectively inject slurry into the deep part of the crack, becomes the key to improving the repair effect. SUMMARY

[0006] The purpose of the present application is to solve the problems existing in the prior art, and to provide a concrete micro-crack fog vaporization repair material and its preparation and use method. The present application is not only suitable for repairing micro-cracks in tunnel lining concrete, but also can be used in various engineering projects such as civil and water conservancy projects that require penetration repair, such as concrete micro-crack repair of dams, bridges, etc.

[0007] A concrete micro-crack fog vaporization repair material, comprising A liquid, B liquid and C powder; wherein the A liquid is a urease-containing aqueous solution, or a urease-containing sodium alginate solution, or a urease-containing sodium alginate-nanofiber solution; the B liquid is a mixture of calcium ions and urea solution, the calcium ion concentration is 1-2mol / L, and the urea concentration is 1-3mol / L; the C powder is a microencapsulated repair agent.

[0008] Preferably, the calcium source is calcium acetate or calcium chloride.

[0009] Preferably, the urease-containing bacteria in the A liquid is Bacillus pasteurii or / and Ureococcus, and the urease activity in the A liquid is 50-60mmol / (L·min).

[0010] Preferably, the sodium alginate solution containing urease bacteria is obtained by adding a urease bacteria-containing bacterial solution into a sodium alginate aqueous solution, and the final mass fraction of sodium alginate is 0.25-2.5%.

[0011] Preferably, the sodium alginate-nanofiber solution containing urease bacteria is obtained by adding a urease bacteria-containing bacterial solution into a sodium alginate and nanofiber-containing aqueous solution, and the final mass fraction of sodium alginate is 0.25-2.5%, and the final mass fraction of nanofiber is 0.25-2.5%.

[0012] Preferably, the nanofiber is cellulose nanofiber.

[0013] Preferably, the A liquid further contains Clostridium butyricum and Saccharomyces cerevisiae, and the ratio of the viable counts of Clostridium butyricum, Saccharomyces cerevisiae and urease bacteria is 1-2:1-2:2-4.

[0014] The present application adds Clostridium butyricum and Saccharomyces cerevisiae into the urease bacterial solution, which can promote the MICP process through synergistic metabolism, microenvironment regulation, template provision and other ways. First, the metabolic products produced by Clostridium butyricum and Saccharomyces cerevisiae can provide carbon sources, and the carbon dioxide released by metabolism can reduce the pH value of alkaline concrete to a certain extent, creating favorable conditions for the growth of urease bacteria. Second, the released carbon dioxide also helps to increase the concentration of carbonate ions, which is conducive to the precipitation of calcium carbonate. The cell surface of yeast and Clostridium butyricum may have certain electric charge or biological macromolecules (such as polysaccharides and proteins), which can act as crystal nucleation templates to promote the nucleation and deposition of calcium carbonate on the surface of microorganisms. Third, the mixed bacterial system may form synergistic metabolism, such as yeast providing biological active substances such as vitamins and amino acids to promote the activity of urease bacteria.

[0015] Preferably, the C powder is a microencapsulated repair agent.

[0016] Preferably, the mass ratio of the A liquid, the B liquid and the C powder is 1:1:0.2-0.4. Specifically, in the following repair process, the mass ratio of the A liquid mist vaporization droplets, the B liquid mist vaporization droplets and the C powder mist aerosol is 1:1:0.2-0.4.

[0017] Preferably, the microencapsulated repair agent is prepared by the following steps: mixing fly ash, potassium feldspar, sodium silicate and sodium aluminate, wet grinding and granulating to obtain a core material; adding amino-terminated polyamide amine and polyethylene glycol into a solvent and stirring uniformly, adding the core material and mixing uniformly, and spray drying.

[0018] The fly ash is compounded with potassium feldspar, sodium silicate and sodium aluminate, and is subjected to atomization and drying to perform surface micro-capsule treatment, and after mist vaporization, aerosols are formed and uniformly enter the cracks, and the sodium alginate and nanofibers in the A liquid have good affinity, and a synergistic effect is generated to effectively fill the cracks and effectively enhance the crack strength. In the presence of water, the fly ash reacts with the potassium feldspar, sodium silicate and sodium aluminate and expands, and the cracks are repaired by the microorganisms, which not only has a fast repair response, but also can ensure effective filling of the cracks, and the crack interface structure is dense, and the product has excellent mechanical properties and excellent durability.

[0019] Preferably, the mass ratio of the fly ash, the potassium feldspar, the sodium silicate, the sodium aluminate, the terminal amino polyamide amine and the polyethylene glycol is 10-20:1-5:1-2:1-2:0.1-1:1-2.

[0020] Preferably, the particle size of the core material is 50-100 μm.

[0021] A concrete micro-crack mist vaporization repair method comprises the following steps: tightly attaching a sealing cover of a mist vaporization device and an air extraction cover of an air extraction device to two ends of a concrete crack respectively; applying sealing paint to the concrete crack not covered by the sealing cover or the air extraction cover; mist vaporizing A liquid, B liquid and C powder of the concrete micro-crack mist vaporization repair material by using the mist vaporization device, and simultaneously performing air extraction by using the air extraction device, so that the mist vaporization treatment obtained micro-droplets or aerosols sufficiently cover the section surface of the concrete crack due to pressure difference and convection.

[0022] After the C powder is mist vaporized, aerosols with a particle size of 100-150 μm are formed, which can be stably suspended in the cracks, uniformly diffuse with air convection, realize uniform distribution and deep penetration of the repair material, and dissolve to release active ingredients and form deposits after meeting water in the cracks, thereby filling and repairing the cracks in a certain time.

[0023] The number and distribution of mist vaporization nozzles of the mist vaporization device can be adjusted according to the distribution of the crack network. When the crack network distribution range is wide (the diameter is greater than 2 m) or the number of cracks in the range of 2 m diameter exceeds 5, mist vaporization nozzles need to be added. Generally, a 2 m diameter circle is taken as one repair unit (one repair unit contains one mist vaporization nozzle).

[0024] The mist vaporization device is one of a pneumatic mist vaporization device (10-100 μm), a mechanical mist vaporization device (20-200 μm) or an ultrasonic mist vaporization device (0.1-10 μm), and the diameters of the mist vaporization droplets generated by different mist vaporization devices are different, which can be suitable for crack repair of different opening degrees.

[0025] In the lining crack network, for the microcrack with average crack opening less than 0.1mm, the ultrasonic fog atomization device can be used, for the microcrack with average crack opening between 0.1mm and 0.3mm, the ultrasonic fog atomization or pneumatic fog atomization device can be selected, and for the crack with average crack opening greater than 0.3mm, the pneumatic fog atomization device or the mechanical fog atomization device can be selected.

[0026] The sealing cover and the air extraction cover are closely attached to the concrete surface through silica gel pads and silica gel adhesives, so that the fog atomization slurry is prevented from leaking out.

[0027] Advantages:

[0028] 1. The synergistic effect of the fog atomization device, the negative pressure air extraction device and the sealing coating can effectively improve the penetration depth of the slurry, and ensure that the repair liquid fully covers the inside of the crack, especially the deep part.

[0029] 2. The fog atomization A liquid and the B liquid can better mix and react in the crack, generate more calcium carbonate precipitates, and enhance the repair effect.

[0030] 3. The butyric acid clostridium in the A liquid and the saccharomyces cerevisiae can promote the MICP process through synergistic metabolism, microenvironment regulation and template provision.

[0031] 4. The sealing cover effectively prevents the fog atomization slurry from leaking out, reduces waste, and improves the grouting efficiency.

[0032] 5. The method is not only suitable for concrete microcrack repair, but also can be used in the occasions requiring penetration repair in civil engineering, water conservancy and other fields, such as concrete microcrack repair of dams and bridges. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Fig. 1 is a schematic diagram of the microstructure of the repair product obtained by the method of the present application; wherein (a) is a schematic diagram of the microstructure of the fog atomization repair process; (b) is a schematic diagram of the microstructure of the repair product.

[0034] Figure 2A schematic diagram of the concrete micro-crack fog vaporization repair method proposed in the present application, that is, a schematic diagram of repairing the vertical cracks at position A in the tunnel by using the concrete micro-crack fog vaporization repair method proposed in the present application; wherein the arrows represent the fog vapor flow direction.

[0035] Figure 3 A schematic diagram of the combination of the sealing cover / air suction cover and the crack.

[0036] Figure 4 A schematic diagram of the fog vaporization device.

[0037] Figures 2-4 In the figure, 1 is the fog vaporization device, 2 is the air suction device, 3 is the sealing coating sealing area, 4 is the silica gel pad, 5 is the silica gel adhesive, 11 is the sealing cover, 12 is the fog vaporization switch, 13 is the container containing liquid A, 14 is the container containing liquid B, 15 is the container containing powder C, and 21 is the air suction cover.

[0038] Figure 5 A comparison chart of the relative permeability coefficients of the standard concrete samples with cracks repaired by using the repair materials and repair methods obtained in Example 1, Example 6 and Comparative Examples 1-3.

[0039] Figure 6 A comparison chart of the compressive strength recovery rate and the flexural strength recovery rate of the standard concrete samples with cracks repaired by using the repair materials and repair methods obtained in Example 1, Example 6 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0040] The present application will be further described below in conjunction with specific embodiments.

[0041] Example 1

[0042] A concrete micro-crack fog vaporization repair material, comprising liquid A, liquid B and powder C.

[0043] In the present application, the liquid A is a bacillus pasteurii bacterial solution, and the urease activity in the liquid A is 60 mmol / (L·min); the liquid B is a mixed solution of calcium acetate and urea, and the calcium ion concentration is 1.2 mol / L and the urea concentration is 1.8 mol / L.

[0044] The powder C is a micro-encapsulated repair agent. The micro-encapsulated repair agent is prepared by the following steps: 30g of fly ash, 6g of potassium feldspar, 3g of sodium silicate and 3g of sodium aluminate are stirred uniformly, anhydrous ethanol is added for wet grinding, and granulation is performed to obtain a core material with an average particle size of 70μm; 1g of amino-terminated polyamide amine, 3g of polyethylene glycol 600 are added to 160g of anhydrous ethanol and stirred uniformly, and the core material is added and mixed uniformly, and spray drying is performed.

[0045] A concrete micro-crack fog vaporization repair method, comprising the following steps:

[0046] The fog vaporization nozzle is sealed by a sealing cover on the outside, which is tightly attached to the crack surface to form a closed space, preventing the fog vaporization slurry from leaking outward.

[0047] An air extraction device is installed at the other end of the crack network to extract air and create a negative pressure environment (-10 kPa); the negative pressure value is adjusted according to the depth and width of the crack to maintain air convection inside the crack and promote the penetration of the slurry; a micron-level filtration device is provided to collect the liquid for secondary fog vaporization repair.

[0048] The nearby extension cracks are sealed with paint to ensure that the entire crack network has only the fog sealing cover as the inlet and the air extraction cover as the outlet.

[0049] A, B and C powder are stored in separate containers, the appropriate fog vaporization device is selected according to the actual crack width, and the injection pressure and liquid flow of the nozzle are adjusted to ensure the fineness and uniformity of the droplets; at the same time, the fog vaporization nozzles of the three containers are opened, and the fog vaporization repair is carried out for 5 days, during which A, B and C powder are mixed and sprayed into the crack to react and generate calcium carbonate deposits to fill and repair the crack.

[0050] For cracks with an opening of 0.1-0.3mm, an ultrasonic fog vaporization device is used, the flow is controlled at 50mL / min, the fog vaporization droplet size of A and B is 0.1-10μm, and the C powder aerosol is 100-150μm; the mass ratio of A, B and C powder aerosol is 1:1:0.3.

[0051] Example 2

[0052] The difference between this example and Example 1 is that the A liquid in this example is a sodium alginate solution containing Bacillus pasteurii. The final mass fraction of sodium alginate is 1.5%.

[0053] Example 3

[0054] The difference between this example and Example 1 is that the microencapsulated repair agent in this example is prepared by the following steps: 10g fly ash, 1g potassium feldspar, 1g sodium silicate and 1g sodium aluminate are mixed, wet ground and granulated to obtain a core material with an average particle size of 80μm; 0.1g amino-terminated polyamide amine, 1g polyethylene glycol are added to the solvent and stirred uniformly, and the core material is added and mixed uniformly, and then spray dried.

[0055] Example 4

[0056] The difference from Example 1 is that the A liquid of the present example is a sodium alginate-cellulose nanofiber solution containing Paenibacillus polymyxa. The final mass fraction of sodium alginate is 1.5%, and the final mass fraction of cellulose nanofiber is 1.5%.

[0057] Example 5

[0058] The difference from Example 1 is that the A liquid of the present example is a sodium alginate-cellulose nanofiber solution containing Paenibacillus polymyxa and Streptococcus ureae. The final mass fraction of sodium alginate is 1.5%, and the final mass fraction of cellulose nanofiber is 1.5%, wherein the urease activity is 60 mmol / (L·min).

[0059] Example 6

[0060] The difference from Example 1 is that the A liquid of the present example is a sodium alginate-cellulose nanofiber solution containing a composite bacteria.

[0061] In the A liquid, the composite bacteria include: Paenibacillus polymyxa, Streptococcus ureae, Clostridium butyricum, and Saccharomyces cerevisiae, and the ratio of the viable bacterial count of Paenibacillus polymyxa, Streptococcus ureae, Clostridium butyricum, and Saccharomyces cerevisiae is 3.5:0.5:1:1.

[0062] The urease activity in the A liquid is 60 mmol / (L·min), the final mass fraction of sodium alginate is 1.5%, and the final mass fraction of cellulose nanofiber is 1.5%.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that, in the present comparative example, the mist vaporization of the A liquid container, the B liquid container, and the C powder container are alternately carried out (the mist vaporization nozzle of the A liquid container is opened for 6 h, and the mist vaporization nozzles of the B liquid container and the C powder container are closed at this time; then the mist vaporization nozzle of the A liquid container is closed, and the mist vaporization nozzles of the B liquid container and the C powder container are opened for 6 h). The total mist vaporization time is 5 d.

[0065] Comparative Example 2

[0066] The difference from Example 6 is that, in the present comparative example, the microencapsulated repair agent is prepared by the following steps: 30 g of fly ash, 6 g of potassium feldspar, 3 g of sodium silicate, and 3 g of sodium aluminate are stirred uniformly, and then wet grinding is carried out with anhydrous ethanol to obtain a core material with a particle size of 70 μm; 3 g of polyethylene glycol 600 is added to 160 g of anhydrous ethanol and stirred uniformly, and then the core material is added and mixed uniformly, and then spray drying is carried out.

[0067] Comparative Example 3

[0068] The composite bacteria in the present comparative example include: Bacillus pasteurii, Streptococcus ureae, Saccharomyces cerevisiae, and the ratio of the viable cell number of Bacillus pasteurii, Streptococcus ureae, and Saccharomyces cerevisiae is 3.5:0.5:2.

[0069] Put 900 g of reference cement into a stirring pot, and uniformly add 1350 g of standard sand and 450 g of water into the stirring pot at low speed, and stir for 5 s at low speed and then stir for 15 s at high speed. Pour the mixture into a test mold, vibrate for 30 s, stop the vibration, take out the test mold, scrape off the mortar that is higher than the test mold, and smooth the surface. After marking the test mold, put the test mold into a curing box for natural curing for 28 d to obtain a standard concrete sample.

[0070] After random sampling, test the initial compressive strength and the initial flexural strength, and then use a pressure testing machine to lightly press the remaining sample to cause cracks (while using a clamp to maintain the same crack width), and the preloading speed is 0.1 mm / min, and the pressure value is 60% of the ultimate compressive strength.

[0071] Test the initial permeability coefficient (k0) of the standard concrete sample with cracks, select samples with similar initial permeability coefficients, and use the repair materials and repair methods obtained in Example 1, Example 6, and Comparative Examples 1-3 to repair the standard concrete sample with cracks.

[0072] Again test the permeability coefficient (k) of each group of repaired samples, calculate the relative permeability coefficient (k / k0), and then test the compressive strength and the flexural strength of each group of repaired samples, and calculate the compressive strength recovery rate after repair and the flexural strength recovery rate after repair.

[0073] Compressive strength recovery rate after repair = (compressive strength after repair) ÷ (initial compressive strength) × 100%

[0074] Flexural strength recovery rate after repair = (flexural strength after repair) ÷ (initial flexural strength) × 100%

[0075] As shown in Figure 5 and Figure 6 After repair using the repair materials and repair methods obtained in Example 6, the relative permeability coefficient is the smallest, and the compressive strength recovery rate after repair and the flexural strength recovery rate after repair are the highest, which are better than those of the other groups (P<0.05).

[0076] The applicant believes that: this is due to the synergistic effect of the fog atomization device, the negative pressure air extraction device and the sealing coating, which can effectively improve the penetration depth of the slurry, ensure that the repair liquid fully covers the inside of the crack, especially the deep part; the fog atomized A liquid and B liquid are uniformly distributed in the form of small droplets or aerosols, and can better mix and react in the crack to generate more calcium carbonate precipitates, ensuring uniform repair of the inside of the crack and enhancing the repair effect. Moreover, the butyric acid clostridium in the A liquid and the saccharomyces cerevisiae can promote the MICP process through synergistic metabolism, microenvironment regulation, template provision and other ways. The microencapsulated repair agent of C powder realizes the dense, high-strength and efficient repair of the crack through multiple mechanisms such as physical filling, chemical reaction, coating and slow release, and toughening and reinforcing. The sealing cover effectively prevents the leakage of the fog atomized slurry, reduces waste, and improves the grouting efficiency. The repair liquid is uniformly distributed in the form of small droplets or aerosols, ensuring uniform repair of the inside of the crack. Especially, the aerosol formed by the atomization of C powder has smaller particle size and higher suspension stability, can enter the deep part of the small crack, make up for the deficiency of traditional slurry or small droplets in permeability, ensure that the repair material fully contacts the crack wall, uniformly covers and promotes the occurrence of calcium carbonate precipitation reaction. The method is not only suitable for concrete microcrack repair, but also can be used in engineering such as civil engineering, water conservancy and other fields that require permeability repair, such as concrete microcrack repair of dams, bridges and other concrete microcracks. The repair response is fast, and the effective filling of the crack, the dense structure of the crack interface and the excellent mechanical properties and durability of the product can be ensured.

[0077] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A concrete microcrack fog vaporization repair material, characterized by, Comprise A liquid, B liquid and C powder; the mass ratio of A liquid, B liquid and C powder is 1:1:0.2-0.4; Wherein, A liquid is a urease-containing bacterial aqueous solution, or a urease-containing bacterial sodium alginate solution, or a urease-containing bacterial sodium alginate-nanofiber solution; The urease-containing bacterial sodium alginate solution is obtained by mixing urease-containing bacterial liquid into sodium alginate aqueous solution, and the final mass fraction of sodium alginate is 0.25-2.5%; The urease-containing bacterial sodium alginate-nanofiber solution is obtained by mixing urease-containing bacterial liquid into sodium alginate and nanofiber-containing aqueous solution, and the final mass fraction of sodium alginate is 0.25-2.5%, and the final mass fraction of nanofiber is 0.25-2.5%; B liquid is a mixture of calcium ion and urea solution, the concentration of calcium ion is 1-2mol / L, and the concentration of urea is 1-3mol / L, and the calcium source is calcium acetate or calcium chloride; C powder is a microencapsulated repair agent; the microencapsulated repair agent is prepared by the following steps: mixing fly ash, potassium feldspar, sodium silicate and sodium aluminate, wet grinding and granulating to obtain core material; stirring uniformly amino-terminated polyamide amine and polyethylene glycol in a solvent, adding the core material and mixing uniformly, and spray drying.

2. The concrete micro crack fogging repair material according to claim 1, wherein, The urease-containing bacteria in A liquid are Bacillus pasteurii or / and Streptococcus ureae, and the urease activity in A liquid is 50-60mmol / (L•min).

3. The concrete micro crack fogging repair material according to claim 1, wherein, A liquid also contains Clostridium butyricum and Saccharomyces cerevisiae, and the ratio of the viable counts of Clostridium butyricum, Saccharomyces cerevisiae and urease-containing bacteria in A liquid is 1-2:1-2:2-4.

4. The concrete micro crack fogging repair material of claim 1, wherein, The mass ratio of fly ash, potassium feldspar, sodium silicate, sodium aluminate, amino-terminated polyamide amine, polyethylene glycol is 10-20:1-5:1-2:1-2:0.1-1:1-2.

5. A method of repairing microcracks in concrete by fogging, characterized in that, The steps include: tightly attaching the sealing cover of the mist vaporization device and the air extraction cover of the air extraction device to the two ends of the concrete crack respectively; and applying sealing paint to the concrete crack not covered by the sealing cover or the air extraction cover; The A liquid, B liquid and C powder of the concrete microcrack mist vaporization repair material according to any one of claims 1-4 are subjected to mist vaporization treatment by the mist vaporization device to form microdroplets or aerosols; At the same time, the air extraction device performs air extraction treatment, so that the microdroplets or aerosols fully cover the cross-sectional surface of the concrete crack due to the pressure difference and convection.

6. The method of claim 5, wherein the method further comprises: The C powder forms aerosols with a particle size of 100-150μm after being atomized.

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