A method and system for targeted regulation of interface transition zone of existing concrete substrate repair

Abstract

This invention belongs to the field of concrete repair and provides a method and system for targeted control of the transition zone at the repair interface of existing concrete substrates. The method for targeted control of the transition zone at the repair interface of existing concrete substrates includes calculating the average micromechanical properties and the average phase content of each segment at different distances from the repair interface; fitting the average micromechanical properties of each segment at different distances from the repair interface with the average content of each phase to determine the phase category that has the greatest impact on the micromechanical properties; based on the fitting relationship between the micromechanical properties and the phase that has the greatest impact, determining the content and distribution of the phase that has the greatest impact on the micromechanical properties corresponding to the set micromechanical property requirements, and thus obtaining a matching composition and proportion control scheme for the repair material. This improves the accuracy of targeted control of the repair interface of existing concrete substrates.

Description

Technical Field

[0001] This invention belongs to the field of concrete repair, and in particular relates to a method and system for targeted control of the transition zone of the repair interface of existing concrete matrix. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Concrete infrastructure operating in harsh environments inevitably experiences concrete deterioration during its service life, such as concrete spalling, chloride erosion and cracking, and water erosion. To ensure the normal or even extended service life of concrete infrastructure, repair is necessary. The repair interface is a weak point in the repair system, and repair materials are prone to debonding, leading to a recurring repair dilemma for extending the lifespan of concrete infrastructure. The weakness of the repair interface is due to the "sidewall effect," which causes calcium hydroxide to accumulate and preferentially orient itself, resulting in a loose transition zone and weak micro- and nano-scale mechanical interlocking forces. Targeted control of the micro- and nano-scale mechanical interlocking forces at the repair interface is difficult, as they are influenced by hydration products, unhydrated cementitious materials, and the formation and distribution of pores in the interface transition zone.

[0004] In the prior art, publication number CN116577171A provides a method and system for evaluating the repair interface transition zone based on the phase hardness difference. This method can determine the thickness of the repair interface transition zone, which is of guiding significance for the control of interface performance. However, since the three-dimensional elevation roughness characterization of the interface transition zone is used, the phases of the products in the repair interface transition zone cannot be distinguished. Therefore, it is impossible to accurately determine the content and distribution of the products in the repair interface transition zone, and thus it cannot provide accurate guidance for the targeted control of the repair interface of existing concrete matrix.

[0005] Furthermore, existing technologies mostly study interface transition zones where there are no similar components between steel fibers or aggregates and cement-based materials, and where the aggregates or steel fibers are surrounded by cement-based materials. In this case, the interface transition profile can form a closed profile. However, when the existing concrete and the repair material have similar components, they undergo interactive chemical reactions, and the existing concrete structure is not covered by the repair material, the interface transition zone analysis profile cannot form a closed profile. This makes phase analysis and content determination in the interface transition zone difficult. Therefore, existing analytical methods are not suitable for situations where the existing concrete and repair material have similar components and the existing concrete structure is not covered by the repair material, thus hindering the targeted control of the interface in the repair of existing concrete matrices. Summary of the Invention

[0006] To address the technical problems mentioned above, this invention provides a method and system for targeted control of the transition zone at the repair interface of existing concrete substrates. This method is applicable to situations where there are similar components between existing concrete and repair materials, and the existing concrete structure is not covered by the repair materials. It can improve the accuracy of targeted control of the repair interface of existing concrete substrates.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a method for targeted control of the transition zone at the repair interface of existing concrete matrix.

[0009] A method for targeted control of the transition zone at the interface of existing concrete matrix repair, comprising:

[0010] Obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several equally spaced dividing lines in sequence to form several dividing intervals.

[0011] The micromechanical properties of the existing concrete repair interface at different distances from the sample are obtained. The average micromechanical properties of each interval at different distances from the repair interface are calculated according to the intervals.

[0012] The phase analysis results of each segment of the transition zone of the existing concrete repair interface of the sample were obtained. The average content of each phase in all segments at different distances of the repair interface was calculated to obtain the average content of each phase in each segment at different distances of the repair interface.

[0013] The micromechanical property values ​​of each segment at different distances of the repair interface are fitted with the average content of each corresponding phase to determine the phase category that has the greatest impact on the micromechanical property values.

[0014] Based on the fitting relationship between the micromechanical property values ​​and the phases that have the greatest impact on them, the content and distribution of the phases that have the greatest impact on the micromechanical property values ​​corresponding to the set micromechanical property value requirements are determined, and then the composition and proportion control scheme of the matching repair material is obtained.

[0015] In one embodiment, the phase includes phase pores, hydration products, and unhydrated cementitious materials.

[0016] As one implementation method, when the pore size is the phase type that has the greatest impact on the micromechanical properties, the water-cement ratio of the mixture system in the repair material is adjusted to reduce the water-cement ratio of the mixture system, decrease the pore content of the repair material, and enhance the micromechanical properties of the transition zone at the repair interface.

[0017] As one implementation method, when the unhydrated cementitious material is the phase category that has the greatest impact on the micromechanical properties, the material containing the pozzolanic effect component is introduced into the repair material component, or the amount of the pozzolanic effect component material is increased.

[0018] As one implementation method, when the hydration products are the phase category that has the greatest impact on the micromechanical properties, the optimization direction of the repair material is to control the content of hydration products in the repair material, and to introduce nanomaterial components into the repair material to provide nucleation sites for the hydration products.

[0019] As one implementation method, nanoindentation testing technology or microhardness testing technology is used to obtain the micromechanical property values ​​at different distances from the existing concrete repair interface of the sample.

[0020] As one implementation method, the process of obtaining the boundary contour line of the transition zone at the repair interface of the existing concrete matrix of the sample is as follows:

[0021] Obtain an image of the transition zone at the interface of the existing concrete repair, and remove the existing concrete area and the aggregate in the repair material to make it a white area.

[0022] Adjust the brightness and contrast of the image after removing the white areas;

[0023] The line connecting the white area and the gray area in the image after brightness and contrast adjustment is used as the boundary outline of the interface transition area.

[0024] As one implementation method, backscattered image analysis is used to obtain the phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample.

[0025] As one implementation method, CT (Computed Tomography) scans are used to analyze the phase composition of each segment in the transition zone of the existing concrete repair interface of the sample.

[0026] A second aspect of the present invention provides a targeted control system for the transition zone of the repair interface of existing concrete matrix.

[0027] A targeted control system for the transition zone of an existing concrete matrix repair interface includes:

[0028] The partitioning module is used to obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several partition lines at equal distances in sequence, forming several partitioning intervals.

[0029] The module for calculating the average micromechanical properties is used to obtain the micromechanical property values ​​distributed at different distances from the existing concrete repair interface of the sample, and to calculate the average micromechanical properties of each interval at different repair interface distances according to the intervals.

[0030] The average phase content calculation module is used to obtain the phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample. It calculates the average phase content of each segment in all segments at different distances from the repair interface to obtain the average phase content of each segment at different distances from the repair interface.

[0031] The module for determining the most influential phase is used to fit the average micromechanical properties of each segment at different distances of the repair interface with the average content of each corresponding phase to determine the phase category that has the greatest impact on the micromechanical properties.

[0032] The repair material control scheme determination module is used to determine the content and distribution of the phase that has the greatest influence on the micromechanical properties, based on the fitting relationship between the micromechanical property values ​​and the phase that has the greatest influence on them, and then obtain the matching composition and ratio control scheme of the repair material.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) This invention is applicable to situations where there are similar components between existing concrete and repair materials, and the existing concrete structure is not covered by the repair materials. By finding the boundary contour line of the transition zone of the existing concrete matrix repair interface and constructing the separation interval by translation, boundary conditions are provided for the subsequent micromechanical performance test and phase analysis of the interface transition zone of the separation interval. In addition, by combining the fitting relationship between the average micromechanical performance at different distances of the repair interface and the average content of each phase, the relationship between the phase characterization and the micromechanical performance value of the repair interface transition zone is realized. The phase category with the greatest influence on the micromechanical performance value is determined. Finally, the content and distribution of the phase with the greatest influence on the micromechanical performance value are deduced to achieve the set micromechanical performance value requirements. In addition, by controlling the composition and ratio of the repair material, the precise control of the bonding performance of the interface transition zone is guided.

[0035] (2) In this invention, the existing concrete area and the aggregate in the repair material are removed into white areas. The line connecting the white area and the image display area in the image after brightness and contrast adjustment is used as the boundary outline of the interface transition area. The boundary outline is translated to generate several equidistant dividing lines, forming several dividing intervals. The phases in each dividing interval are then analyzed, which improves the accuracy of phase analysis and lays a data foundation for targeted control of the repair interface of the existing concrete matrix.

[0036] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0038] Figure 1 This is an N-1 backscattered image according to an embodiment of the present invention;

[0039] Figure 2 The present invention embodiment N-1 involves the removal of existing concrete and aggregates;

[0040] Figure 3 This refers to the selection of the N-1 threshold in this embodiment of the invention;

[0041] Figure 4 This refers to the calculation of the N-1 pore content in an embodiment of the present invention;

[0042] Figure 5 This is the N-1 hydration product content meter of this invention embodiment;

[0043] Figure 6 This refers to the calculation of the N-1 unhydrated cementitious material content in this embodiment of the invention;

[0044] Figure 7 This is the relationship between the N-1 pore content and the elastic modulus in an embodiment of the present invention;

[0045] Figure 8 This is the relationship between the N-1 hydration product content and the elastic modulus in an embodiment of the present invention;

[0046] Figure 9 This is the relationship between the content of N-1 unhydrated cementitious material and the elastic modulus in an embodiment of the present invention;

[0047] Figure 10 This describes the relationship between N-2 pore content and elastic modulus in an embodiment of the present invention.

[0048] Figure 11 This is the relationship between the N-2 hydration product content and the elastic modulus in an embodiment of the present invention;

[0049] Figure 12 This is the relationship between the content of N-2 unhydrated cementitious material and the elastic modulus in an embodiment of the present invention;

[0050] Figure 13 This is a flowchart of the targeted control method for the transition zone of the existing concrete matrix repair interface according to an embodiment of the present invention;

[0051] Figure 14This is a schematic diagram of the structure of the targeted control system for the transition zone of the existing concrete matrix repair interface according to an embodiment of the present invention. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0053] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0054] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0055] according to Figure 13 In one or more embodiments, a method for targeted control of the transition zone at the repair interface of an existing concrete matrix is ​​provided, which specifically includes the following steps:

[0056] Step S101: Obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several equally spaced dividing lines to form several dividing intervals.

[0057] In one or more embodiments, the preparation process of the specimen for the transition zone of the existing concrete matrix repair interface is as follows:

[0058] (a) Take a core sample at the interface between the existing concrete matrix and the repair material. The core sample diameter is 2-3 mm. The core sample direction is parallel to the repair interface, but the core sample contains the interface portion.

[0059] (b) Cut the core sample after core extraction into cylindrical shapes with a height of 1.5cm-3cm.

[0060] (c) Place the cut sample in a silicone mold in a vacuum container with a vacuum pressure of not less than 0.096 MPa. Then, pour high-flow epoxy resin into the silicone mold and wait for the epoxy resin to impregnate into the cement-based material pores in the interface transition zone for not less than 5 minutes. After the epoxy resin has cured, demold. This step can effectively prevent the pore wall from collapsing and being damaged during the subsequent polishing process, thereby eliminating potential errors that affect the phase content of the interface transition zone.

[0061] (d) Next, the sample is polished to repair the interface transition area.

[0062] (d1) Place the sample in an automatic polishing machine and first use sandpaper to coarsely grind it. The sandpaper should be 800-1200 grit. Apply a pressure of 13N-18N with the grinding head. The upper grinding disc rotates at 100r / min-120r / min and the lower grinding disc rotates at 180r / min-200r / min. Continue polishing until the impregnated existing concrete repair interface is exposed. Use anhydrous ethanol as a lubricant during polishing. Clean with anhydrous ethanol for no less than 8 minutes. After replacing with anhydrous ethanol, clean again for no less than 5 minutes.

[0063] (d2) Further polishing is performed using 1200-1800 grit sandpaper. The pressure applied by the grinding head is 13N-18N, the upper grinding disc speed is 100r / min-120r / min, the lower grinding disc speed is 180r / min-200r / min, and the polishing time is 3-5min. Anhydrous ethanol is used as the lubricant during the polishing process. Anhydrous ethanol is used for cleaning for 8min, and after replacing with anhydrous ethanol, it is cleaned again for 5min.

[0064] (d3) Further polishing is performed using a polishing cloth. The pressure applied by the grinding head is 13N-15N, the upper grinding disc speed is 80r / min-100r / min, the lower grinding disc speed is 150r / min-180r / min, the polishing time is 3min-5min, a 9μm diamond polishing film is used, and anhydrous ethanol is used as the lubricant during the polishing process. Anhydrous ethanol cleaning is performed for no less than 8min, and after replacing with anhydrous ethanol, cleaning is performed again for no less than 5min.

[0065] (d4) Further polishing is performed using a polishing cloth. The pressure applied by the grinding head is 11N-13N, the upper grinding disc speed is 80r / min-90r / min, the lower grinding disc speed is 150r / min-160r / min, the polishing time is 3min-5min, a 3μm diamond polishing film is used, and anhydrous ethanol is used as the lubricant during the polishing process. Anhydrous ethanol cleaning is performed for no less than 8min, and after replacing with anhydrous ethanol, cleaning is performed again for no less than 5min.

[0066] (d5) Further polishing is performed using a polishing cloth. The pressure applied by the grinding head is 9N-11N, the upper grinding disc speed is 70r / min-85r / min, the lower grinding disc speed is 140r / min-155r / min, the polishing time is 3min-5min, a diamond polishing film of 1μm is used, and anhydrous ethanol is used as the lubricant during the polishing process. Anhydrous ethanol cleaning is performed for no less than 8min, and after replacing with anhydrous ethanol, cleaning is performed again for no less than 5min.

[0067] It is understood here that, in other embodiments, those skilled in the art may also use other methods to prepare samples of the existing concrete matrix repair interface transition zone, which will not be described in detail here.

[0068] In the specific implementation process, the process of obtaining the boundary contour line of the transition zone of the existing concrete matrix repair interface of the sample is as follows:

[0069] Obtain an image of the transition zone at the existing concrete repair interface (this image can be a backscattered image or a CT image, etc.), and remove the existing concrete area and the aggregate in the repair material to make it a white area.

[0070] Adjust the brightness and contrast of the image after removing the white areas;

[0071] The line connecting the white area and the gray area in the image after brightness and contrast adjustment is used as the boundary outline of the interface transition area.

[0072] In this embodiment, the existing concrete area and the aggregate in the repair material are removed to form a white area. The line connecting the white area and the image display area in the image after brightness and contrast adjustment is used as the boundary outline of the interface transition zone. The boundary outline is translated to generate several equally spaced dividing lines, forming several dividing intervals. The phases in each dividing interval are then analyzed, which improves the accuracy of phase analysis and lays a data foundation for targeted control of the repair interface of the existing concrete matrix.

[0073] Step S102: Obtain the micromechanical property values ​​at different distances from the existing concrete repair interface of the sample, and calculate the average micromechanical property value of each interval at different distances from the repair interface according to the interval.

[0074] It should be noted here that the micromechanical properties include, but are not limited to, the elastic modulus and the hardness.

[0075] In the specific implementation process, the elastic modulus values ​​at different distances from the existing concrete repair interface of the sample are obtained using nanoindentation testing technology.

[0076] In other embodiments, microhardness testing techniques can be used to obtain hardness values ​​distributed at different distances from the existing concrete repair interface of the sample.

[0077] Taking the nanoindentation testing technique for obtaining elastic modulus values ​​as an example:

[0078] The prepared samples were subjected to mechanical property testing of the transition zone at the repair interface of existing concrete using a nanoindentation tester. The test area was approximately 50μm-100μm parallel to the length of the repair interface and approximately 90μm-120μm perpendicular to the length of the repair interface. The vertical or horizontal distance between nanoindentation test points was 10μm-15μm. To distinguish indentations of different phases, the applied load was determined based on the maximum indentation depth range of 100nm-300nm. Loading was performed at a uniform rate, reaching the maximum load in 30s, holding the load for 10s, and then lowering it at the same constant rate. After the test, the instrument provided the test results for the elastic modulus.

[0079] When using nanoindentation testing technology, the spacing between the dividing lines is the same as the spacing between the nanoindentation points perpendicular to the interface. The distance of the last dividing line from the boundary contour line is the same as the farthest distance of the nanoindentation point perpendicular to the interface.

[0080] For example, the spacing between the dividing lines is 10μm-15μm, until the last dividing line is 90μm-120μm away from the boundary outline.

[0081] Step S103: Obtain the phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample, and average the phase content of each segment at different distances of the repair interface to obtain the average phase content of each segment at different distances of the repair interface.

[0082] In some embodiments, backscattered image analysis is used to obtain the phase analysis results of each segment of the transition zone of the existing concrete repair interface of the sample. The specific process is as follows:

[0083] By taking threshold points corresponding to different phases, a binarized image is obtained. The ratio of the area of ​​the black region in each strip to the total area of ​​the strip is calculated, and the content percentage of the phase (e.g., pores, unhydrated cementitious materials, hydration products) in the strip is calculated.

[0084] In other embodiments, CT scan analysis is used to obtain phase analysis results of each segment of the transition zone of the existing concrete repair interface of the sample.

[0085] Step S104: Fit the average micromechanical properties of each segment at different distances of the repair interface with the average content of each phase to determine the phase category that has the greatest impact on the micromechanical properties.

[0086] Step S105: Based on the fitting relationship between the micromechanical property values ​​and the phase that has the greatest impact on them, determine the content and distribution of the phase that has the greatest impact on the micromechanical property values ​​corresponding to the set micromechanical property value requirements, and then obtain the matching composition and ratio control scheme of the repair material.

[0087] The following section uses the elastic modulus value as an example to explain the control scheme in detail:

[0088] The higher the elastic modulus of the interface transition zone, the denser the interface transition zone, and the higher the bonding strength of the repaired interface; the lower the elastic modulus of the interface transition zone, the more porous the interface transition zone, and the lower the bonding strength of the repaired interface.

[0089] When the pore size of the phase has the greatest impact on the micromechanical properties (such as the elastic modulus), the water-cement ratio of the mixture system in the repair material is adjusted to reduce the water-cement ratio of the repair material mixture system, reduce the pore content of the repair material, and enhance the micromechanical properties (such as the elastic modulus) of the transition zone at the repair interface.

[0090] For example, a 10% change in pore content is beneficial to increasing the elastic modulus of the interfacial transition zone by 30%, a 15% change in the content of unhydrated cementitious materials is beneficial to increasing the elastic modulus of the interfacial transition zone by 15%, and a 12% change in the content of hydration products is beneficial to increasing the elastic modulus of the interfacial transition zone by 13%.

[0091] As can be seen from the above results, the change in pore content has the most significant impact on the elastic modulus of the interface transition zone. At this point, the optimization direction of the repair material is to control the porosity of the repair material. The water-cement ratio of the repair material mixture system can be adjusted and reduced. This is conducive to making the repair material more compact, reducing the pore content of the repair material, and thus enhancing the elastic modulus of the repair interface transition zone. This will help improve the interfacial bonding strength.

[0092] When the unhydrated cementitious material is the phase category that has the greatest impact on the elastic modulus value, the material containing the pozzolanic effect component will be introduced into the repair material, or the amount of the pozzolanic effect component will be increased.

[0093] For example, a 15% change in pore content is beneficial to increasing the elastic modulus of the interfacial transition zone by 13%, a 10% change in the content of unhydrated cementitious materials is beneficial to increasing the elastic modulus of the interfacial transition zone by 25%, and a 10% change in the content of hydration products is beneficial to increasing the elastic modulus of the interfacial transition zone by 15%.

[0094] As can be seen from the above results, the change in the content of unhydrated cementitious material has the most significant impact on the elastic modulus of the interfacial transition zone. At this point, the optimization direction of the repair material is to control the content of unhydrated cementitious material. By introducing materials with the pozzolanic effect into the repair material or optimizing the dosage of the pozzolanic effect component, the materials with the pozzolanic effect can react with calcium hydroxide to generate calcium silicate gel, thereby consuming the unhydrated cementitious material and enhancing the elastic modulus of the repair interface transition zone. This will help improve the interfacial bonding strength.

[0095] When hydration products are the phase category that has the greatest impact on micromechanical properties (such as elastic modulus), the optimization direction of the repair material is to control the content of hydration products in the repair material, and to introduce nanomaterial components into the repair material to provide nucleation sites for hydration products.

[0096] For example, a 12% change in pore content is beneficial to increasing the elastic modulus of the interfacial transition zone by 13%, a 12% change in the content of unhydrated cementitious materials is beneficial to increasing the elastic modulus of the interfacial transition zone by 15%, and a 10% change in the content of hydration products is beneficial to increasing the elastic modulus of the interfacial transition zone by 30%.

[0097] As can be seen from the above results, the change in the content of hydration products has the most significant impact on the elastic modulus of the interface transition zone. At this time, the optimization direction of the repair material is to regulate the content of hydration products (such as hydrated cement) in the repair material. By introducing nanomaterial components into the repair material, nucleation sites are provided for the hydration products, promoting the hydration of the products and thus enhancing the elastic modulus of the repair interface transition zone, which will help improve the interfacial bonding strength.

[0098] Example 1:

[0099] The existing concrete was made of ordinary concrete (NC), and the repair material was also made of ordinary concrete (NC). Quantitative evaluation and targeted control of the transition zone at the interface of the existing concrete matrix repair were carried out.

[0100] (1) Core samples were taken from the interface between the existing concrete matrix and the repair material. The core diameter was 2.5 mm, and the core sampling direction was parallel to the repair interface, but the core sample included the interface portion. The core sample was then cut into a 2 cm high cylinder. The cut sample was placed in a silicone mold in a vacuum container with a vacuum pressure of 0.098 MPa. Then, high-flow-rate epoxy resin was poured into the silicone mold, and the mold was allowed to stand for 5 minutes. After 24 hours, the epoxy resin cured and the sample was demolded. The sample was placed in an automatic polishing machine. First, it was coarsely ground with 800-grit sandpaper. The grinding head applied 15N of pressure, the upper grinding disc rotated at 120 rpm, and the lower grinding disc rotated at 200 rpm. Polishing continued until the impregnated existing concrete repair interface was exposed. Anhydrous ethanol was used as the lubricant during this process. Next, 1500-grit sandpaper was used for further polishing. The grinding head applied 15N of pressure, the upper grinding disc rotated at 100 rpm, and the lower grinding disc rotated at 200 rpm for 5 minutes. Anhydrous ethanol was used as the lubricant during this process. Cleaning with anhydrous ethanol for 8 minutes was followed by a 5-minute cleaning process after replacing the ethanol. Finally, polishing was performed with a polishing cloth. The grinding head applied 14N of pressure, the upper grinding disc rotated at 100 rpm, and the lower grinding disc rotated at 160 rpm for 5 minutes. A 9μm diamond polishing film was used, and anhydrous ethanol was used as the lubricant during this process. Further polishing was performed using a polishing cloth. The grinding head applied a pressure of 12N, the upper grinding disc rotated at 90 rpm, and the lower grinding disc rotated at 160 rpm. The polishing time was 4 minutes, and a 3μm diamond polishing film was used. Anhydrous ethanol was used as the lubricant during the polishing process. Further polishing was performed using a polishing cloth. The grinding head applied a pressure of 9N, the upper grinding disc rotated at 80 rpm, and the lower grinding disc rotated at 150 rpm. The polishing time was 3 minutes, and a 1μm diamond polishing film was used. Anhydrous ethanol was used as the lubricant during the polishing process. After each stage of polishing, the surface was cleaned twice with anhydrous ethanol for 8 minutes and 5 minutes respectively.

[0101] (2) The prepared samples were subjected to mechanical property testing of the transition zone at the existing concrete repair interface. A nanoindentation tester was used. The test area was approximately 50 μm long parallel to the repair interface and approximately 100 μm long perpendicular to the repair interface. The vertical or horizontal distance between the nanoindentation test points was 10 μm. To distinguish the indentations of different phases, a load of 15 mN was applied. The loading was carried out at a uniform rate, and the time to reach the maximum load was 30 s. The load was held for 10 s and then lowered at the same constant rate to obtain the elastic modulus data, as shown in Table 1.

[0102] Table 1. Elastic modulus results (GPa) of the transition zone at the N-1 repair interface.

[0103]

[0104] (3) The sample after nanoindentation testing was sputter-coated with gold and then placed in a scanning electron microscope equipped with a backscattering probe for observation in BSE mode to obtain BSE images of the repair interface transition zone, such as... Figure 1 As shown, the BSE image must be within the same range as the nanoindentation point test area. The existing concrete area in the BSE image is removed to create a white area, and the aggregate in the repair material is also removed to create a white area, as shown below. Figure 2 As shown; adjust the brightness and contrast of the image, using the intersection line between the white area and the image area as the boundary contour line of the interface transition zone. This contour line is not closed and is irregular. Separating lines are generated sequentially at equal intervals using a translation method, with a spacing of 10μm between the dividing lines, until the last dividing line is 100μm away from the boundary contour line. Threshold points corresponding to different phases are selected to obtain a binarized image, as shown. Figures 3-6 As shown in Table 2, the ratio of the area of ​​the black region in each strip to the total area of ​​the strip was statistically analyzed, and the content ratio of the phases (pores, unhydrated cementitious materials, hydration products) in the strip was calculated.

[0105] Table 2. Phase content and distribution results (%) of the N-1 repair interface transition zone

[0106]

[0107]

[0108] (4) Statistically calculate the average elastic modulus of nanoindentation tests within the dividing strips. Establish mathematical relationships between phase pores, unhydrated cementitious materials, hydration products, and elastic modulus within the same region and strip through data fitting, such as... Figures 7-9 As shown, in order to reduce experimental error, multiple regions were selected for testing and the average value was taken.

[0109] Results analysis:

[0110] The N-1 interface transition zone, which is close to the repair interface, has high porosity and low elastic modulus. Due to the sidewall effect, the interface may have high water content, high porosity, and a low proportion of hydration products, resulting in a low elastic modulus. This makes the repair interface relatively weak and the repair material prone to debonding. In order to precisely control the phase of the interface transition zone, silica fume can be added to the repair material. This component has a pozzolanic effect, which can improve the structural compactness of the interface transition zone, reduce porosity, and promote product hydration. In addition, using a low water-cement ratio in the repair material can effectively improve interface bleeding, thereby reducing the porosity at the interface.

[0111] Example 2:

[0112] To verify the effectiveness of the precise phase control effect of the interface transition zone guided by the present invention, based on the results of Example 1 and the precise phase control recommendations given in Example 1, composite specimens of old and new concrete were prepared. The existing concrete was made of ordinary concrete (NC), and the repair material was made of ultra-high performance concrete (UHPC). Silica fume was added to the UHPC component, and the water-cement ratio of the repair material system in Example 1 was reduced from 0.48 to 0.19. Quantitative evaluation and targeted control of the interface transition zone of the existing concrete matrix repair were carried out.

[0113] (1) Sample preparation follows the same steps and parameter selection as in Example 1;

[0114] (2) The prepared samples were subjected to mechanical property testing of the transition zone at the existing concrete repair interface. A nanoindentation tester was used. The test area was approximately 50 μm long parallel to the repair interface and approximately 100 μm long perpendicular to the repair interface. The vertical or horizontal distance between the nanoindentation test points was 10 μm. To distinguish the indentations of different phases, a load of 15 mN was applied. The loading was carried out at a uniform rate, and the time to reach the maximum load was 30 s. The load was held for 10 s and then lowered at the same constant rate to obtain the elastic modulus data, as shown in Table 3.

[0115] Table 3. Elastic modulus results (GPa) of the transition zone at the N-2 repair interface.

[0116]

[0117] (3) The samples tested for nanoindentation were sputter-coated with gold and then placed in a scanning electron microscope equipped with a backscattering probe for observation. The observation mode was BSE mode, and a BSE image of the transition zone of the repair interface was obtained. The BSE image should be the same as the test range of the nanoindentation points. The existing concrete area in the BSE image was removed to make it a white area. The brightness and contrast of the image were adjusted, and the line of intersection between the white area and the image area was taken as the boundary contour line of the interface transition zone. This contour line is not closed and is irregular. Equally spaced dividing lines were generated sequentially by translation, with a spacing of 10 μm between the dividing lines, until the last dividing line was 100 μm away from the boundary contour line. Threshold points corresponding to different phases were taken to obtain a binary image. The ratio of the area of ​​the black area in each strip to the total area of ​​the strip was calculated, and the content ratio of the phase (pores, unhydrated cementitious materials, hydration products) in the strip was calculated, as shown in Table 4.

[0118] Table 4. Phase content and distribution results (%) of the N-2 repair interface transition zone.

[0119]

[0120]

[0121] (4) Statistically calculate the average elastic modulus of nanoindentation tests within the dividing strips. Establish mathematical relationships between phase pores, unhydrated cementitious materials, hydration products, and elastic modulus within the same region and strip through data fitting, such as... Figures 10-12 As shown. To reduce experimental error, multiple regions were selected for testing, and the average value was taken.

[0122] Results analysis:

[0123] Example 2 was carried out based on the interface control suggestions given in Example 1. The results of Example 2 show that the porosity structure of the N-2 interface transition zone was significantly optimized, the hydration ratio of the product was increased, the elastic modulus of the repair interface transition zone was improved, the microstructure of the interface transition zone was made denser, and the porosity was reduced. From a microscopic perspective, this is beneficial to the improvement of the macroscopic bonding performance of the interface, thus verifying the effectiveness of the present invention.

[0124] In one or more embodiments, such as Figure 14 As shown, a targeted control system for the transition zone of the repair interface in existing concrete matrix is ​​also provided, which specifically includes the following modules:

[0125] The partitioning module 201 is used to obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several partition lines at equal distances in sequence to form several partitioning intervals.

[0126] The micromechanical property mean value calculation module 202 is used to obtain the micromechanical property values ​​distributed at different distances from the existing concrete repair interface of the sample, and calculate the mean micromechanical property value of each interval at different distances from the repair interface according to the interval.

[0127] The average phase content calculation module 203 is used to obtain the phase analysis results of each partition in the transition zone of the existing concrete repair interface of the sample, and to average the phase content of each partition at different distances of the repair interface to obtain the average phase content of each partition at different distances of the repair interface.

[0128] The module 204 for determining the phase with the greatest impact is used to fit the average value of the micromechanical properties of each segment at different distances of the repair interface with the average value of the content of each phase to determine the phase category with the greatest impact on the micromechanical properties.

[0129] The repair material control scheme determination module 205 is used to determine the content and distribution of the phase that has the greatest influence on the micromechanical properties corresponding to the set micromechanical property value requirements, based on the fitting relationship between the micromechanical property values ​​and the phase that has the greatest influence on them, and then obtain the matching component and ratio control scheme of the repair material.

[0130] It should be noted that the specific implementation process of the modules 201 (separation interval division module), 202 (average value calculation module for micromechanical properties), 203 (average value calculation module for phase content), 204 (determination module for the phase with the greatest influence), and 205 (determination module for the control scheme of repair materials) are the same as the specific implementation process of each step in the existing method for targeted control of the transition zone of the repair interface of concrete matrix, and will not be repeated here.

[0131] 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 method for targeted control of the transition zone at the interface of existing concrete matrix repair, characterized in that, include: Obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several equally spaced dividing lines in sequence to form several dividing intervals. The micromechanical properties of the existing concrete repair interface at different distances from the sample were obtained, and the average micromechanical properties of each interval at different distances from the repair interface were calculated according to the intervals. The phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample were obtained. The average content of each phase in all segments at different distances of the repair interface was calculated to obtain the average content of each phase in each segment at different distances of the repair interface. The average micromechanical properties of each segment at different distances of the repair interface are fitted with the average content of each corresponding phase to determine the phase category that has the greatest impact on the micromechanical properties. Based on the fitting relationship between the micromechanical property values ​​and the phase that has the greatest impact on them, the content and distribution of the phase that has the greatest impact on the micromechanical property values ​​corresponding to the set micromechanical property value requirements are determined, and then the composition and ratio control scheme of the matching repair material is obtained. The phase includes phase pores, hydration products, and unhydrated cementitious materials; The process of obtaining the boundary contour of the transition zone at the repair interface of the existing concrete matrix of the sample is as follows: Obtain an image of the transition zone at the interface of the existing concrete repair, and remove the existing concrete area and the aggregate in the repair material to make it a white area. Adjust the brightness and contrast of the image after removing the white areas; The line connecting the white area and the gray area in the image after brightness and contrast adjustment is used as the boundary outline of the interface transition area.

2. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, When the pore size is the phase type that has the greatest impact on the micromechanical properties, the water-cement ratio of the mixture system in the repair material is adjusted to reduce the water-cement ratio of the mixture system, decrease the pore content of the repair material, and enhance the micromechanical properties of the transition zone at the repair interface.

3. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, When the unhydrated cementitious material is the phase category that has the greatest impact on the micromechanical properties, the material composition that incorporates the pozzolanic effect component or increases the amount of the pozzolanic effect component will be repaired.

4. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, When hydration products are the phase category that has the greatest impact on micromechanical properties, the optimization direction of repair materials is to control the content of hydration products in the repair materials and introduce nanomaterial components into the repair materials to provide nucleation sites for hydration products.

5. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, The micromechanical properties of the existing concrete repair interface at different distances from the sample were obtained using nanoindentation testing technology or microhardness testing technology.

6. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, Backscattered image analysis was used to obtain the phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample.

7. The targeted control method for the transition zone of the repair interface in existing concrete matrix as described in claim 1, characterized in that, The phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample were obtained by CT scanning analysis.

8. A targeted control system for the transition zone of an existing concrete matrix repair interface, characterized in that, This is achieved using the targeted control method for the transition zone of the existing concrete matrix repair interface as described in any one of claims 1-7, comprising: The partitioning module is used to obtain the boundary outline of the transition zone of the existing concrete matrix repair interface of the sample, and translate it to generate several partition lines at equal distances in sequence, forming several partitioning intervals. The module for calculating the average micromechanical properties is used to obtain the micromechanical property values ​​distributed at different distances from the existing concrete repair interface of the sample, and to calculate the average micromechanical properties of each interval at different distances from the repair interface according to the intervals. The average phase content calculation module is used to obtain the phase analysis results of each segment in the transition zone of the existing concrete repair interface of the sample. It calculates the average phase content of each segment at different distances of the repair interface to obtain the average phase content of each segment at different distances of the repair interface. The module for determining the most influential phase is used to fit the average elastic modulus of each segment at different distances of the repair interface with the average content of each corresponding phase to determine the phase category that has the greatest impact on the micromechanical properties. The repair material control scheme determination module is used to determine the content and distribution of the phase that has the greatest influence on the micromechanical properties, based on the fitting relationship between the micromechanical property values ​​and the phase that has the greatest influence on them, and then obtain the matching composition and ratio control scheme of the repair material.

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