Method for determining and repairing apparent damage of concrete members containing steel slag aggregates

Abstract

The application discloses a kind of concrete member apparent damage determination and repair method containing expansion damage source in the technical field of building structure performance diagnosis and treatment.It determines the method of concrete member apparent damage, which includes: a group of concrete core samples drilled in a type of concrete members in the concrete structure are subjected to different experimental methods, and the first and second volume expansion rates reflecting the expansion of steel slag aggregate in the concrete member are determined; an equivalent model of steel slag aggregate is set in the finite element calculation model of the concrete member to simulate the force of the volume expansion of steel slag aggregate on the concrete member, and the surface expansion damage specification is determined according to the force and the design specification of the concrete member. This method can be used to predict the specification that the surface expansion damage of the concrete member may reach, and to treat early to avoid loss.

Description

Technical Field

[0001] This invention relates to the field of building structural performance diagnosis and treatment technology, specifically to a method for determining and repairing apparent damage to concrete components containing steel slag aggregate. Background Technology

[0002] Traditionally, natural pebbles are used as aggregate in concrete. However, in recent years, considering both engineering needs and environmental requirements, some metallurgical slags, such as blast furnace slag and steel slag, have also been used as concrete aggregates. Metallurgical slag, as an industrial byproduct, reduces the need for natural stone mining, lowers carbon emissions, and aligns with the concept of green concrete. Furthermore, the high hardness of metallurgical slags like steel slag makes them suitable for high-strength concrete. Their rough, porous surface results in better bonding strength with cement paste than natural pebbles, improving the compressive and flexural strength of concrete.

[0003] Because steel slag contains f-CaO, it reacts with water to form Ca(OH)2, causing volume expansion. If used in construction without proper processing, it may cause scattered, irregularly distributed point bursting damage on the concrete surface, thus affecting the overall structural safety. The continuous and irregular occurrence of these bursts could severely impact the normal use of the building. However, current assessments and treatments of the safety of concrete structures containing steel slag aggregate are based on the current state of the building and cannot predict the damage to these concrete structural components during their future service life. Summary of the Invention

[0004] The embodiments of this application provide a method for determining and repairing apparent damage to concrete components containing expansion damage sources. This method can be used to predict the possible specifications of expansion damage on the surface of concrete components and to treat it early to avoid losses.

[0005] Firstly, this application provides a method for determining apparent damage to concrete components, applicable to scenarios where the concrete component includes steel slag aggregate causing surface expansion damage. This method is used to determine the expected surface expansion damage specifications of a class of concrete components included in a concrete structure. The method includes: drilling a set of concrete core samples from the concrete component, wherein the concrete component belongs to the same category and has a consistent degree of damage (Class I); experimentally determining a first volumetric expansion rate and a second volumetric expansion rate of the drilled set of concrete core samples, wherein both the first and second volumetric expansion rates reflect the volumetric expansion rate of the steel slag aggregate in the concrete component; setting an equivalent model of the steel slag aggregate in the finite element calculation model of the concrete component to simulate the force exerted by the volumetric expansion of the steel slag aggregate on the concrete component; determining the surface expansion damage specifications based on the force and the design specifications of the concrete component, wherein the volumetric expansion rate of the equivalent model of the steel slag aggregate is the larger of the first and second volumetric expansion rates; and the design specifications are the concrete grade, concrete mix proportion, and / or steel reinforcement density of the Class I concrete component.

[0006] The method for determining apparent damage to concrete components provided in this application first determines the different volumetric expansion rates that steel slag aggregate may cause to cause surface expansion damage to concrete components based on multiple concrete core samples obtained by drilling. Then, based on the different volumetric expansion rates and the location of the drilled concrete core samples, a finite element calculation model of the concrete component is constructed to simulate the external compressive stress that the concrete component may be subjected to. In this way, the tensile stress generated by the expansion effect of steel slag aggregate is estimated, thereby enabling the prediction of the surface expansion damage specifications that the concrete component may produce within a target time, that is, the depth and range of surface damage caused by the expansion and cracking of free calcium oxide on the concrete surface.

[0007] In one possible implementation, the first volumetric expansion rate is determined based on the expansion rate induced by the steel slag aggregate in a set of concrete core samples, and the second volumetric expansion rate is determined based on the volumetric expansion induced by free calcium oxide in the steel slag aggregate.

[0008] Furthermore, in another possible implementation, the first volume expansion rate and the second volume expansion rate are determined through the following steps:

[0009] Steel slag aggregate was extracted from a set of concrete core samples to determine the average content of the extracted steel slag aggregate in the set of concrete core samples.

[0010] Based on the average content, test specimens of concrete components are made, and the test specimens are treated according to the first preset physical conditions. The first volume expansion rate of the test specimens is then measured.

[0011] The first content of free oxides in a portion of the dismantled steel slag aggregate was determined by chemical titration. The other portion of the dismantled steel slag aggregate was treated under second preset physical conditions, and the second content of free oxides in this second portion was determined by chemical titration. The second volume expansion rate of the steel slag aggregate was determined based on the difference between the first and second contents.

[0012] The first preset physical conditions include: continuously curing the test piece in a constant temperature water bath environment for a first preset time at a first preset temperature; the second preset physical conditions include: continuously curing another part of the steel slag aggregate in a second preset temperature and preset pressure environment for a second preset time.

[0013] Furthermore, in another possible implementation, when determining the first volume expansion rate, a control specimen is also prepared for the comparison specimen. The specifications of the control specimen are consistent with those of the concrete component, and the material of the control specimen does not include steel slag aggregate that causes expansion damage to the surface of the concrete component. The first volume expansion rate is the volume expansion rate of the first specimen after treatment under the first preset physical conditions compared with that of the second specimen after treatment under the first preset physical conditions.

[0014] In another possible implementation, the first preset temperature ranges from 78°C to 82°C, the first preset time is 3 days, 7 days, 14 days, 21 days, 28 days, 35 days, or 42 days, the second preset temperature ranges from 95°C to 100°C, the preset pressure is 0.8 MPa to 1.2 MPa, and the second preset time is 1.5 hours to 3 hours.

[0015] In another possible implementation, for a second type of concrete member in a concrete structure, wherein the second type of concrete member is a concrete member belonging to the same category and having the same degree of damage, but different in category and / or degree of damage from the first type of concrete member, the surface expansion damage specification of the second type of concrete member is determined by the following steps:

[0016] Second set of concrete core samples were drilled from the second type of concrete components;

[0017] The first and second volume expansion rates of the second set of concrete core samples obtained by drilling were determined through experiments.

[0018] In the finite element calculation model of the second type of concrete component, an equivalent model of steel slag aggregate of the second type of concrete component is set up to simulate the second force of the volume expansion of steel slag aggregate of the second type of concrete component on the second type of concrete component. The surface expansion damage specification of the second type of concrete component is determined according to the second force and the design specification of the second type of concrete component.

[0019] Secondly, this application provides a method for repairing apparent damage to concrete components, which can be used in scenarios where concrete components already have apparent damage or may develop apparent damage in the future. The method includes: determining the depth of the apparent damage to be repaired extending from the surface of the concrete component inward according to the method for determining apparent damage to the concrete component in this application, wherein the depth is determined according to the surface expansion damage specification; and replacing the concrete from the surface of the concrete component to the depth with concrete that meets the repair requirements.

[0020] In one possible implementation, a set of concrete core samples drilled is determined based on the location of the apparent damage to be repaired.

[0021] The method for repairing surface damage to concrete components provided in this application takes into account that free calcium oxide inside the concrete component is unlikely to expand and burst upon contact with water, thus preventing damage. Even if there is a small possibility of expansion upon contact with water, the pressure inside the concrete component is sufficient to offset the expansion pressure, making it difficult to cause structural damage. Therefore, the method mainly considers the depth of surface damage caused by the expansion and bursting of free calcium oxide and replaces the concrete from the surface to the depth of the concrete component with concrete that meets the repair requirements, which can enable the concrete component to be repaired to achieve the ideal treatment effect.

[0022] Thirdly, this application provides a method for repairing apparent damage to concrete structures, which can be used in scenarios where concrete structures including different concrete components already have apparent damage or may develop apparent damage in the future. The method includes: selecting a first batch of concrete components from the concrete structure to be repaired; and repairing the selected first batch of concrete components according to the method for repairing apparent damage to concrete components of this application, wherein the selection criteria for the first batch of concrete components are: belonging to the same production batch, belonging to the same construction batch, and / or exposed to similar environmental conditions.

[0023] In one possible implementation, the method for repairing apparent damage to a concrete structure further includes: selecting a second batch of concrete members from the concrete structure to be repaired; and repairing the selected second batch of concrete members according to the method for repairing apparent damage to concrete members of this application, wherein the selection criteria for the second batch of concrete members are different from the selection criteria for the first batch of concrete members.

[0024] The method for repairing apparent damage to concrete structures provided in this application involves treating the concrete components in the concrete structure to be repaired in batches. That is, the concrete components are divided into different batches for treatment according to the production batch, component type, and / or degree of damage. For each batch of concrete components, the depth of surface expansion damage that may occur within a target time is estimated, and the concrete within the estimated depth range of each batch of concrete components is replaced with the concrete required for repair. This allows different batches of concrete components to achieve the ideal treatment effect, thereby achieving the ideal treatment effect for the overall structural performance of the building. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart illustrating a method for determining apparent damage to concrete components according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] The embodiments of this application provide a method for determining apparent damage to concrete components, which can be applied to scenarios where the concrete component includes steel slag aggregate that causes expansion damage to the surface of the concrete component. The implementation process is as follows: Figure 1 As shown, to predict the specifications of expansion damage that may occur in a concrete member containing steel slag aggregate within a target time, such as the depth and length of cracks caused by the damage, the following steps are performed:

[0029] Step 101: Drill a set of concrete core samples from the concrete components, wherein the concrete components belong to the same category and have the same degree of damage, which are Class I concrete components.

[0030] It should be noted that since core sampling itself can damage concrete components or the building as a whole, unless the burst damage at a location that has a significant impact on the concrete component or the overall building structure already meets the requirements for core sampling, concrete core samples should be drilled at locations that have the least impact on the concrete component or the overall building structure.

[0031] Step 102: Determine the first volume expansion rate and the second volume expansion rate of a set of drilled concrete core samples through experiments. The first volume expansion rate and the second volume expansion rate both reflect the volume expansion rate of steel slag aggregate in the concrete component.

[0032] Step 103: Set up an equivalent model of steel slag aggregate in the finite element calculation model of the concrete component to simulate the force of the volume expansion of steel slag aggregate on the concrete component. Determine the surface expansion damage specifications based on the force and the design specifications of the concrete component. The volume expansion rate of the equivalent model of steel slag aggregate is the larger of the first volume expansion rate and the second volume expansion rate. The design specifications are the concrete grade, concrete mix proportion and / or steel reinforcement density of the first type of concrete component.

[0033] In one possible implementation, the first volumetric expansion rate is determined based on the expansion rate induced by steel slag aggregate in a set of concrete core samples, and the second volumetric expansion rate is determined based on the volumetric expansion induced by free calcium oxide in the steel slag aggregate. Step 102 includes the following sub-steps:

[0034] Step 1021: Separate the steel slag aggregate from each of the drilled concrete core samples one by one, and calculate the substitution rate of steel slag aggregate for ordinary concrete aggregate.

[0035] Step 1022: Determine the first volumetric expansion rate based on physical experiments. Specifically, mortar rod specimens are prepared according to the substitution rate of steel slag aggregate for ordinary concrete aggregate, and the expansion rate of the mortar rod specimens is observed to obtain the maximum linear expansion rate of the specimens. The first volumetric expansion rate is then calculated based on the linear expansion rate.

[0036] Step 1023: Determine the second volumetric expansion rate based on chemical experiments. Specifically, take the steel slag aggregate separated in step 1021, and determine its expansion source content using autoclaving and chemical titration methods; calculate the second volumetric expansion rate based on the expansion source content.

[0037] Technicians can calculate the first and second volume expansion rates based on existing technologies, and this application does not impose any restrictions.

[0038] Specifically, in step 1021, the total mass of coarse aggregate in the concrete core sample can be calculated based on the mass of the concrete core sample and the concrete mix proportion. Then, the mass percentage of the separated steel slag relative to the total mass of the coarse aggregate can be calculated, which is the substitution rate of the steel slag for ordinary concrete aggregate in the corresponding concrete core sample.

[0039] Furthermore, in one possible implementation, step 1022 includes the following sub-steps:

[0040] Step 10221: Prepare a control specimen of mortar rod according to the predetermined ratio of water, cement and sand. That is, the control specimen is a mortar rod specimen that does not include steel slag aggregate, which may cause surface expansion damage.

[0041] Step 10222: Replace the sand in the predetermined proportion of water, cement and sand with steel slag aggregate that may cause surface expansion damage according to the replacement rate calculated in step 1021, and make mortar rod specimens.

[0042] Step 10223: After both the mortar rod specimen and the control specimen are formed, they are placed in a predetermined temperature and humidity environment for curing for a predetermined time, then demolded and the initial length of the mortar rod specimen is measured. The mortar rod specimen is then placed in a predetermined constant temperature environment for curing.

[0043] Step 10224: Track and observe the mortar rod specimens and control specimens, and measure the length of the mortar rod specimens and control specimens one by one at predetermined time intervals until the length of the mortar rod specimens and control specimens stabilizes. Then calculate the maximum linear expansion rate of the mortar rod specimens and control specimens respectively.

[0044] Step 10225: Compare the maximum linear expansion rates of the steel slag sand specimen and the control specimen, and calculate the second volumetric expansion rate.

[0045] It should be noted that the environment for curing the mortar rod specimens and control specimens can be: a constant temperature environment with a temperature range of 78℃ to 82℃, and the mortar rod specimens and control specimens are monitored and observed for 3 days, 7 days, 14 days, 21 days, 28 days, 35 days or 42 days for the length of the mortar rod specimens and control specimens to stabilize.

[0046] It should also be noted that the size of the mortar rod specimen can be 25mm×25mm×280mm, the cement can be selected according to the construction requirements of the target concrete component, and the sand can be selected according to the specifications of the sand or standard sand according to the construction requirements of the target concrete component.

[0047] In one possible implementation, step 1023 includes the following sub-steps:

[0048] Step 10231: Take out two portions of equal mass from the steel slag aggregate separated in step 1021;

[0049] Step 10232: The first content of free calcium oxide in one sample is directly determined by chemical titration, that is, the mass percentage of free calcium oxide;

[0050] Step 10233: Another sample is subjected to a pressure steaming test. The sample is placed in a pressure steaming kettle and steamed at 1 MPa for 2 hours according to the relevant standard operating requirements. The second content of free calcium oxide is then determined by chemical titration, which is the mass percentage of free calcium oxide after pressure steaming.

[0051] Step 10234: Calculate the mass percentage of free calcium oxide in the steel slag aggregate that may undergo oxidation reaction, i.e., the difference between the first content and the second content;

[0052] Step 10235: Estimate the second volume expansion rate based on the difference obtained in step 10234.

[0053] It should be noted that the experimental conditions for the above-mentioned autoclaving test can also be: working temperature range of 95℃ to 100℃, preset pressure of 0.8MPa to 1.2MPa, and autoclaving duration of 1.5 hours to 3 hours.

[0054] In one possible implementation, the finite element model of the concrete component in step 103 can be designed so that the steel slag expands freely under unconstrained conditions. Finite element software is used to consider different distributions of the steel slag aggregate and to simulate the damage of concrete components containing this type of steel slag. The initial stress method is used to simulate the expansion effect of the aggregate. The slag-like aggregate is equivalent to a sphere of a certain diameter. Uniform initial compressive stress is applied to the sphere in all directions during the simulation. When the external constraints are removed, the volume of the sphere expands, and the initial stress eventually drops to zero.

[0055] The volumetric expansion rate of aggregate under unconstrained conditions is taken as the initial expansion rate. For aggregate that has undergone volumetric expansion, the actual volumetric expansion rate will be less than the initial expansion rate under unconstrained conditions because it is constrained in the concrete. At this time, the concrete is subjected to tensile stress due to the expansion of aggregate. In the calculation, the concrete tensile stress is transformed into apparent cracks. This is the apparent damage of concrete members containing steel slag aggregate under long-term expansion effect.

[0056] This embodiment predicts the development law of expansion damage in steel slag concrete components based on experimental analysis and structural calculations. First, core samples are drilled from existing similar concrete components containing steel slag aggregate. The core samples are then broken open to separate the steel slag aggregate. After determining the average steel slag content in the concrete, physical and chemical tests are conducted. In the physical tests, expansion rate test specimens are made using steel slag. The specimens are cured in a high-temperature water bath, and their expansion rate is tested periodically. After the expansion of the specimens stabilizes, the steel slag expansion rate is calculated based on the measured expansion rates of control specimens and steel slag specimens. In the chemical tests, the change in the content of free calcium oxide in the steel slag before and after autoclaving is used to calculate the content of reactive free calcium oxide in the steel slag, thereby deriving the volumetric expansion rate of the steel slag. For a safer approach, the larger value calculated from the physical and chemical tests is taken as the steel slag volumetric expansion rate for the damage prediction model. Considering different distributions of steel slag, the strain calculation results of the finite element method are converted into apparent cracks in the concrete component. This represents the damage specification for the long-term expansion of concrete components containing steel slag aggregate.

[0057] It should be noted that different concrete components in a concrete structure have different raw materials, construction methods, and environmental factors, requiring separate estimation of their apparent damage under long-term expansion effects. Therefore, different concrete components in a concrete structure can be classified based on the aforementioned differentiating factors and the existing apparent losses. For each category of concrete component, steps 101-103 are performed to drill multiple sets of concrete core samples. For each set of core samples, the first and second volumetric expansion rates reflecting the category of concrete component are determined experimentally. A finite element model of the concrete component reflecting the volumetric expansion of that category is then established to simulate the force exerted by the volumetric expansion of the steel slag aggregate on that category of concrete component, determining the surface expansion damage specifications. That is, in step 101, sampling can be done in batches, selecting surface burst damage locations with similar damage levels for each batch of core samples, resulting in a final set of core samples from multiple batches. The data from each batch of concrete core samples can correspond to the concrete core samples from different parts mentioned in step 102, and be numbered and recorded respectively. Then, when constructing the finite element calculation model of the concrete component in step 103, an equivalent model of steel slag aggregate is constructed for each batch of concrete core samples selected in step 101, and the drilling location is determined according to the numbering record. This allows for a more accurate determination of the surface expansion damage specifications of the concrete component, and thus a more precise prediction of the long-term expansion damage specifications of concrete components containing steel slag aggregate. Specific steps can be referred to in the execution process of steps 101-103 and their sub-steps above, and will not be detailed further in this application.

[0058] This application also provides a method for repairing apparent damage to concrete components. This method can be used in scenarios where concrete components already have apparent damage or may develop apparent damage in the future. Considering that free calcium oxide inside the concrete component is unlikely to expand and burst upon contact with water, causing damage, even if there is a small possibility of expansion, the internal pressure of the concrete component is sufficient to offset the expansion pressure, making it difficult to cause structural damage. Therefore, the method primarily considers the depth of surface damage caused by the expansion and bursting of free calcium oxide, replacing the concrete from the surface to the depth of the concrete component with concrete that meets the repair requirements. This allows the concrete component to achieve the desired treatment effect. The method includes: determining the depth of the apparent damage to be repaired from the surface of the concrete component inward, according to the method for determining apparent damage of the concrete component in this application, the depth being determined based on the surface expansion damage specifications; and replacing the concrete from the surface to the depth of the concrete component with concrete that meets the repair requirements.

[0059] In one possible implementation, a set of concrete core samples drilled is determined based on the location of the apparent damage to be repaired.

[0060] This application also provides a method for repairing apparent damage to concrete structures. This method can be used in scenarios where concrete structures, including different concrete components, already have apparent damage or may develop apparent damage in the future. The concrete components in the structure to be repaired are treated in batches. That is, the concrete components are divided into different batches for treatment based on production batch, component type, and / or degree of damage. For each batch of concrete components, the potential depth of surface expansion damage within a target time is estimated, and the concrete within the estimated depth range of each batch is replaced with the concrete required for repair. This ensures that different batches of concrete components achieve the desired treatment effect, thereby achieving the desired treatment effect for the overall structural performance of the building. The method includes: selecting the first batch of concrete components from the concrete structure to be repaired; repairing the selected first batch of concrete components according to the method for repairing apparent damage to concrete components of this application. The selection criteria for the first batch of concrete components are: belonging to the same production batch, belonging to the same construction batch, and / or exposed to similar environmental conditions.

[0061] In one possible implementation, the method for repairing apparent damage to a concrete structure further includes: selecting a second batch of concrete members from the concrete structure to be repaired; and repairing the selected second batch of concrete members according to the method for repairing apparent damage to concrete members of this application, wherein the selection criteria for the second batch of concrete members are different from the selection criteria for the first batch of concrete members.

[0062] It should be noted that the implementation parameters in the embodiments disclosed in this specification can be flexibly selected according to the actual conditions such as the building use environment to be determined, and are not limited to the numerical range adopted in this embodiment; the specific implementation steps can also be combined according to the actual situation or adjusted according to the implementation specifications or standards of the construction industry to meet the actual needs.

[0063] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0064] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining apparent damage to concrete members, used to determine the expected surface expansion damage specifications of concrete members included in a concrete structure, wherein, The concrete component includes steel slag aggregate that causes expansion damage to the surface of the concrete component, characterized in that it includes: A set of concrete core samples were drilled from the concrete member, wherein the concrete member belonged to the same category and had the same degree of damage as the first type of concrete member; The first volume expansion rate and the second volume expansion rate of the set of concrete core samples obtained by drilling were determined by experiment, wherein the first volume expansion rate and the second volume expansion rate both reflect the volume expansion rate of the steel slag aggregate in the concrete component. An equivalent model of steel slag aggregate is set in the finite element calculation model of the concrete component to simulate the force of the volume expansion of the steel slag aggregate on the concrete component. The surface expansion damage specification is determined according to the force and the design specifications of the concrete component. The volume expansion rate of the equivalent model of steel slag aggregate is the larger of the first volume expansion rate and the second volume expansion rate. The design specifications are the concrete grade, concrete mix proportion and / or steel reinforcement density of the first type of concrete component. The first volume expansion rate is determined based on the expansion rate caused by the steel slag aggregate in the set of concrete core samples, and the second volume expansion rate is determined based on the volume expansion caused by free calcium oxide in the steel slag aggregate; The first volume expansion rate and the second volume expansion rate are determined by the following steps: The steel slag aggregate was extracted from the set of concrete core samples, and the average content of the extracted steel slag aggregate in the set of concrete core samples was determined. Based on the average content, a prototype of a concrete component is prepared, the prototype is treated according to the first preset physical conditions, and the first volume expansion rate of the prototype is measured. The first content of free oxides in a portion of the dismantled steel slag aggregate was determined by chemical titration. Another portion of the dismantled steel slag aggregate was treated under second preset physical conditions, and the second content of free oxides in this second portion was determined by chemical titration. The second volume expansion rate of the steel slag aggregate was determined based on the difference between the first and second contents. The first preset physical conditions include: continuously curing the prototype in a constant temperature water bath environment at a first preset temperature for a first preset time; the second preset physical conditions include: continuously curing the other part of the steel slag aggregate in a second preset temperature and preset pressure environment for a second preset time.

2. The method for determining apparent damage to concrete components according to claim 1, characterized in that, When determining the first volume expansion rate, a control piece is also made to compare the test piece with the specifications of the concrete component, and the material of the control piece does not include the steel slag aggregate that causes expansion damage to the surface of the concrete component. The first volume expansion rate is the volume expansion rate of the first prototype after being treated under the first preset physical conditions compared to the volume expansion rate of the second prototype after being treated under the first preset physical conditions.

3. The method for determining apparent damage to concrete components according to claim 1, characterized in that, The first preset temperature ranges from 78°C to 82°C, the first preset time is 3 days, 7 days, 14 days, 21 days, 28 days, 35 days or 42 days, the second preset temperature ranges from 95°C to 100°C, the preset pressure is 0.8MPa to 1.2MPa, and the second preset time is 1.5 hours to 3 hours.

4. The method for determining apparent damage to a concrete member according to any one of claims 1-3, characterized in that, For the second type of concrete member in the concrete structure, wherein the second type of concrete member is a concrete member belonging to the same category and with the same degree of damage, but different in category and / or with a different degree of damage from the first type of concrete member, the surface expansion damage specification of the second type of concrete member is determined by the following steps: A second set of concrete core samples were drilled from the second type of concrete component; The first and second volume expansion rates of the second group of concrete core samples obtained by drilling were determined through experiments. In the finite element calculation model of the second type of concrete component, an equivalent model of steel slag aggregate of the second type of concrete component is set up to simulate the second force of the volume expansion of the steel slag aggregate of the second type of concrete component on the second type of concrete component. The surface expansion damage specification of the second type of concrete component is determined according to the second force and the design specification of the second type of concrete component.

5. A method for repairing apparent damage to concrete components, characterized in that, include: The method for determining apparent damage to a concrete member according to any one of claims 1-4, wherein the depth of the apparent damage to be repaired extending inward from the surface of the concrete member is determined according to the surface expansion damage specification; as well as The concrete from the surface of the concrete member to the specified depth will be replaced with concrete that meets the repair requirements.

6. The method for repairing apparent damage to concrete components according to claim 5, characterized in that, The set of concrete core samples drilled is determined based on the location of the apparent damage to be repaired.

7. A method for repairing apparent damage to concrete structures, characterized in that, include: Select the first batch of concrete components from the concrete structure to be repaired; as well as The method for repairing apparent damage to concrete components according to claim 5 or 6, wherein the selected first batch of removed concrete components is repaired. The selection criteria for the first concrete component are: belonging to the same production batch, belonging to the same construction batch, and / or being exposed to similar environmental conditions.

8. The method for repairing apparent damage to concrete structures according to claim 7, characterized in that, Also includes: Select a second batch of concrete components from the concrete structure to be repaired; as well as The method for repairing apparent damage to concrete components according to claim 5 or 6 is used to repair the selected second batch of concrete components. The selection criteria for the second concrete component differ from those for the first concrete component.

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