Method for determining and repairing apparent damage of concrete member containing steel slag aggregate

Abstract

The invention discloses a method for determining and repairing apparent damage of a concrete member containing an expansion damage source in the technical field of building structure performance diagnosis and treatment. The method for determining the apparent damage of the concrete member comprises the following steps: performing different experimental methods on a group of concrete core samples drilled from one type of concrete members in a corresponding concrete structure, and determining a first volume expansion rate and a second volume expansion rate which are generated by steel slag aggregate expansion in the concrete members; a steel slag aggregate equivalent model is arranged in the concrete member finite element calculation model, the acting force of volume expansion of steel slag aggregate on the concrete member is simulated, and the surface expansion damage specification is determined according to the acting force and the design specification of the concrete member. The method can be used for predicting the specification which the surface expansion damage of the concrete member can reach, and early treatment is carried out to avoid loss.

Description

Technical Field

[0001] The present invention relates to the technical field of building structure performance diagnosis and treatment, and in particular to a method for determining and repairing apparent damage of a concrete component containing steel slag aggregate. Background Art

[0002] Traditionally, natural pebbles have been used as concrete aggregates. However, in recent years, due to a comprehensive balance between project requirements and environmental protection, some metallurgical slags, such as blast furnace slag and steel slag, have also been incorporated as concrete aggregates. As an industrial byproduct, using metallurgical slag as aggregate can reduce natural stone mining, lower carbon emissions, and align with the concept of green concrete. Furthermore, the high hardness of metallurgical slag, such as steel slag, is well-suited to high-strength concrete. Their rough and porous surface provides a stronger bond with cement paste than natural pebbles, improving the concrete's compressive and flexural properties.

[0003] Because steel slag contains f-CaO, which reacts with water to form Ca(OH)2, causing it to expand in volume, if used in construction without proper processing, scattered, irregularly distributed point-bursting damage may occur on the concrete surface, compromising the overall safety of the structure. The continuous and irregular appearance of these points can seriously impact the normal use of the building. However, current assessments and diagnostics of the safety of concrete structures containing steel slag aggregates are based on the current state of the building, and are unable to predict the damage to these concrete components over their intended future service life. Summary of the Invention

[0004] The embodiments of the present application provide a method for determining and repairing apparent damage of a concrete component containing an expansion damage source, which can be used to predict the specifications that the surface expansion damage of the concrete component may reach and to treat it early to avoid losses.

[0005] In a first aspect, the present application provides a method for determining apparent damage of a concrete component, which can be applied to a scenario where the concrete component includes steel slag aggregate that causes surface expansion damage of the concrete component, and is used to determine the expected surface expansion damage specification of a type of concrete component included in a concrete structure. The method includes: drilling a group of concrete core samples from the concrete component, wherein the concrete components are first-type concrete components belonging to the same category and having consistent damage degrees; experimentally determining a first volume expansion rate and a second volume expansion rate of the drilled group of concrete core samples, 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; setting a steel slag aggregate equivalent model in a finite element calculation model of the concrete component to simulate the force exerted by the volume expansion of the steel slag aggregate on the concrete component, and determining the surface expansion damage specification based on the force and the design specifications of the concrete component, wherein the volume expansion rate of the steel slag aggregate equivalent model is the larger of the first volume expansion rate and the second volume expansion rate, and the design specifications are the concrete grade, concrete mix ratio, and / or steel density of the first-type concrete component.

[0006] The method for determining the apparent damage of a concrete component provided in this application first determines the different volume expansion rates that may be caused by steel slag aggregate, which may cause surface expansion damage to the concrete component, based on multiple concrete core samples obtained by drilling. Then, based on the obtained different volume expansion rates and the locations 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, and then estimate the tensile stress caused by the expansion of the steel slag aggregate. Therefore, based on the tensile stress, the surface expansion damage specifications that may be generated in the concrete component within a target time can be predicted, that is, the depth and range of the surface damage caused by the expansion and bursting of free calcium oxide on the concrete surface.

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

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

[0009] Demolishing steel slag aggregate from a set of concrete core samples and determining an average content of the demolished steel slag aggregate in the set of concrete core samples;

[0010] making a trial piece of the concrete component according to the average content, treating the trial piece according to a first preset physical condition, and measuring a first volume expansion rate of the trial piece;

[0011] Determining a first content of free oxides in a portion of the broken slag aggregate by chemical titration, treating another portion of the broken slag aggregate according to a second preset physical condition, determining a second content of free oxides in the other portion of the slag aggregate by chemical titration, and determining a second slag volume expansion rate of the slag aggregate according to a difference between the first content and the second content.

[0012] Among them, the first preset physical condition includes: continuously curing the trial product in a constant temperature water bath environment at a first preset temperature for a first preset time; the second preset physical condition includes: continuously curing another part of 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 piece is also produced for comparison with the trial piece. The specifications of the control piece are consistent with the specifications of the concrete component, and the material used to make the control piece does not include steel slag aggregate that causes surface expansion damage to the concrete component. The first volume expansion rate is the volume expansion rate of the first trial piece after being treated according to the first preset physical condition compared to the second trial piece after being treated according to the first preset physical condition.

[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 component in a concrete structure, wherein the second type of concrete component is a concrete component of the same category and with the same damage degree, and is of a different category and / or has a different damage degree than the first type of concrete component, the surface expansion damage specification of the second type of concrete component is determined by the following steps:

[0016] Drilling a second set of concrete core samples from the second type of concrete components;

[0017] Determine the first volume expansion rate and the second volume expansion rate of the second group of concrete core samples drilled through experiments;

[0018] An equivalent model of steel slag aggregate of the second type of concrete component is set in the concrete component finite element calculation model of the second type of concrete component to simulate the second force acting on the second type of concrete component by the volume expansion of the steel slag aggregate of 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] On the second aspect, the present 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 have apparent damage in the future. The method includes: determining the depth to which the apparent damage to be repaired extends from the surface of the concrete component according to the method for determining apparent damage to concrete components of the present application, and the depth is determined according to the surface expansion damage specification; 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 to be drilled is determined based on the location of the apparent damage to be repaired.

[0021] The method for repairing apparent damage to concrete components provided in the present application takes into account that the free calcium oxide inside the concrete component is unlikely to expand and burst when exposed to water, causing damage. Even if there is a small possibility of expansion when exposed to water, the pressure inside the concrete component is sufficient to offset the expansion pressure, making it difficult to cause structural damage. Therefore, the depth of surface damage caused by the expansion and bursting of free calcium oxide is mainly considered. The concrete from the surface of the concrete component to the depth is replaced with concrete that meets the repair requirements, so that the concrete component to be repaired can achieve an ideal diagnosis and treatment effect.

[0022] On the third aspect, the present application provides a method for repairing apparent damage to a concrete structure, which can be used in scenarios where a concrete structure including different concrete components already has apparent damage or may have apparent damage in the future. The method includes: selecting a 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 the present application, wherein the selection conditions for the first concrete components are: belonging to the same production batch, belonging to the same construction batch, and / or being 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 components from the concrete structure to be repaired; and repairing the selected second batch of concrete components according to the method for repairing apparent damage to concrete components of the present application, wherein the selection conditions for the second concrete components are different from the selection conditions for the first concrete components.

[0024] The method for repairing apparent damage to a concrete structure provided in the present application treats 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 concrete meeting the repair requirements, so that the concrete components of different batches can achieve the ideal diagnosis and treatment effect, and thus the overall structural performance of the building can obtain the ideal diagnosis and treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic flow chart of a method for determining apparent damage of a concrete component provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following describes the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

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

[0029] Step 101: Drill a group of concrete core samples from concrete components, wherein the concrete components are first-category concrete components that belong to the same category and have consistent damage degrees.

[0030] It should be noted that since the core sample itself will cause damage to the concrete component or the entire building, unless the explosion point damage at a location that has a greater impact on the concrete component or the overall structure of the building meets the requirements for core sampling, it is necessary to try to choose a location that has less impact on the concrete component or the overall structure of the building to drill concrete core samples.

[0031] Step 102: Determine a first volume expansion rate and a second volume expansion rate of a group of drilled concrete core samples through experiments, wherein 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: Setting a steel slag aggregate equivalent model in the finite element calculation model of the concrete component to simulate the force exerted by the volume expansion of the steel slag aggregate on the concrete component, and determining the surface expansion damage specification based on the force and the design specifications of the concrete component, wherein the volume expansion rate of the steel slag aggregate equivalent model is the larger of the first volume expansion rate and the second volume expansion rate, and the design specifications are the concrete grade, concrete mix ratio, and / or steel density of the first type of concrete component.

[0033] In one possible implementation, the first volume expansion ratio is determined based on the expansion ratio caused by steel slag aggregate in a set of concrete core samples, and the second volume expansion ratio is determined based on the volume expansion caused 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 drilled concrete core sample one by one, and calculate the replacement rate of the steel slag aggregate for ordinary concrete aggregate;

[0035] Step 1022: Determine the first volume expansion rate based on physical testing. Specifically, a mortar bar specimen is prepared based on the replacement rate of steel slag aggregate for ordinary concrete aggregate. The expansion rate of the mortar bar specimen is measured to determine the maximum linear expansion rate of the specimen. The first volume expansion rate is calculated based on the linear expansion rate.

[0036] Step 1023: Determine the second volume expansion ratio based on chemical testing. Specifically, take the steel slag aggregate separated in step 1021, determine its expansion source content by autoclaving and chemical titration, and calculate the second volume expansion ratio 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 the coarse aggregate in the concrete core sample can be calculated based on the mass of the concrete core sample and the concrete mix ratio, and then the mass percentage of the separated steel slag in the total mass of the coarse aggregate can be calculated, which is the replacement rate of the steel slag replacing ordinary concrete aggregate corresponding to the concrete core sample.

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

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

[0041] Step 10222: Replace the sand in the predetermined ratio of water, cement, and sand with steel slag aggregate that may cause surface expansion damage according to the replacement rate calculated in step 1021 to produce a mortar bar specimen.

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

[0043] Step 10224: Track and observe the mortar bar specimen and the control piece, measure the length of the mortar bar specimen and the control piece one by one at a predetermined time interval, and calculate the maximum linear expansion rate of the mortar bar specimen and the control piece after the length of the mortar bar specimen and the control piece stabilizes.

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

[0045] It should be noted that the environment for curing the mortar rod specimens and the control pieces can be: the temperature of the constant temperature environment ranges from 78°C to 82°C, the mortar rod specimens and the control pieces are tracked and observed, and the time for waiting for the length of the mortar rod specimens and the control pieces to stabilize is 3 days, 7 days, 14 days, 21 days, 28 days, 35 days or 42 days.

[0046] It should also be noted that the size of the mortar bar 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 construction requirements of the target concrete component. Sand specifications or standard sand can be selected.

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

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

[0049] Step 10232: directly determining a first content of free calcium oxide in one portion by a chemical titration method, i.e., a mass percentage of free calcium oxide;

[0050] Step 10233: Another sample is subjected to an autoclave test, i.e., the sample is placed in an autoclave and autoclaved at a pressure of 1 MPa for 2 hours in accordance with the operating requirements of relevant standards. Then, a second content of free calcium oxide, i.e., the mass percentage of free calcium oxide after autoclaving, is determined by chemical titration;

[0051] Step 10234: Calculate the mass percentage of free calcium oxide that may undergo oxidation reaction in the steel slag aggregate, that is, 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 of the above-mentioned autoclave test can also be: an operating temperature range of 95° C. to 100° C., a preset pressure of 0.8 MPa to 1.2 MPa, and an autoclave duration of 1.5 hours to 3 hours.

[0054] In one possible implementation, the finite element calculation model for the concrete component in step 103 can assume that the steel slag will expand freely in an unconstrained state. Finite element software is used to consider the different distributions of steel slag aggregates and simulate the damage of concrete components containing such steel slag. The initial stress method is used in the calculation to simulate the expansion effect of the aggregate. The slag aggregate is equivalent to a sphere of a certain diameter. In the simulation, the sphere is given a uniform initial compressive stress in all directions. When the external constraints are removed, the volume of the sphere will expand, and the initial stress will eventually drop to zero.

[0055] The initial expansion rate is the volume expansion rate of the aggregate under unconstrained conditions. For aggregates that undergo volume expansion, the actual volume expansion rate will be less than the initial expansion rate under unconstrained conditions due to the constraints within the concrete. At this time, the concrete is affected by the expansion of the aggregate and generates tensile stress. In the calculation, the tensile stress is converted into apparent cracks, which represents the apparent damage to concrete components containing slag aggregates under the long-term expansion effect.

[0056] This embodiment predicts the development of expansion damage in steel slag concrete components based on experimental analysis and structural calculations. First, a concrete core sample is drilled from an existing similar concrete component containing steel slag aggregate. The core sample is disassembled to separate the steel slag aggregate. The average steel slag content in the concrete is measured, and physical and chemical testing is then conducted. In the physical test, expansion test specimens are made using steel slag. The specimen expansion rate is regularly tested during high-temperature water bath curing. After the specimen expansion stabilizes, the steel slag expansion rate is calculated based on the measured expansion rates of control specimens and steel slag specimens. In the chemical test, the change in the free calcium oxide content in the steel slag before and after autoclaving is used to calculate the reactive free calcium oxide content in the steel slag, and then the volume expansion rate of the steel slag is derived. For a safer approach, the larger of the expansion rates calculated from the physical and chemical tests is used as the steel slag volume expansion rate for the damage prediction model. Taking into account the different distributions of the steel slag, the strain calculation results from the finite element method are converted into apparent cracks in the concrete component. This represents the damage specification for 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, environment and other factors, and their apparent damage under the long-term expansion effect needs to be estimated separately. Therefore, different concrete components in a concrete structure can be classified according to the above-mentioned distinguishing factors and the apparent loss that has occurred. For each category of concrete components, the above steps 101-103 are performed respectively, and multiple groups of concrete core samples are drilled respectively. For each group of drilled concrete core samples, the first volume expansion rate and the second volume expansion rate reflecting the concrete component of this category are determined by experiment. Then, a finite element calculation model of the concrete component that reflects the volume expansion of the concrete component of this category is established, and the force of the volume expansion of the steel slag aggregate of the concrete component of this category on the concrete component of this category is simulated to determine the surface expansion damage specification of the concrete component of this category. That is, in step 101, samples can be taken in batches, and each time a batch of concrete core samples are drilled at the surface explosion point damage location with similar damage degree. Multiple batches of drilling will eventually result in a group of concrete core samples. The data of each batch of concrete core samples can correspond to the concrete core samples of different parts mentioned above in step 102 and be numbered and recorded respectively. Then, when constructing the finite element calculation model of the concrete component in step 103, a steel slag aggregate equivalent model is constructed for each batch of concrete core samples selected in step 101, and the drilling location is determined according to the number record, thereby more accurately determining the surface expansion damage specification of the concrete component and further more accurately predicting the long-term expansion damage specification of the concrete component containing steel slag aggregate. The specific steps can refer to the execution process of the above steps 101-103 and sub-steps, and will not be described in detail in this application.

[0058] The embodiment of the present application also 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 have apparent damage in the future. Considering that the free calcium oxide inside the concrete component is difficult to expand and burst when exposed to water, causing damage, even if there is a small possibility of expansion when exposed to water, the pressure inside the concrete component is sufficient to offset the expansion pressure and it is difficult to cause structural damage. Therefore, the depth of the surface damage caused by the expansion and bursting of free calcium oxide is mainly considered, and the concrete from the surface of the concrete component to the depth is replaced with concrete that meets the repair requirements, so that the concrete component to be repaired can achieve the ideal diagnosis and treatment effect. The method includes: according to the method for determining the apparent damage of the concrete component of the present application, determining the depth of the apparent damage to be repaired extending from the surface of the concrete component to the inside, the depth is determined according to the surface expansion damage specification; replacing the concrete from the surface of the concrete component to the depth with concrete that meets the repair requirements.

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

[0060] The present application also provides a method for repairing apparent damage to a concrete structure, which can be used in scenarios where a concrete structure including different concrete components already has apparent damage or may develop apparent damage in the future. The concrete components in the concrete 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 damage degree. 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 concrete required for repair, so that the different batches of concrete components can achieve the ideal diagnosis and treatment effect, thereby achieving the ideal diagnosis and treatment effect for the overall structural performance of the building. The method includes: selecting a 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 the present application, wherein the selection conditions of the first concrete components are: belonging to the same production batch, belonging to the same construction batch, and / or being 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 components from the concrete structure to be repaired; and repairing the selected second batch of concrete components according to the method for repairing apparent damage to concrete components of the present application, wherein the selection conditions for the second concrete components are different from the selection conditions for the first concrete components.

[0062] It should be noted that the implementation parameters in the embodiments disclosed in this specification can be flexibly selected according to 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 actual conditions or adjusted according to the implementation specifications or standards of the construction industry to meet actual needs.

[0063] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0064] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for determining apparent damage of a concrete member, for determining expected surface expansion damage specifications of a concrete member included in a concrete structure, wherein: The concrete component includes steel slag aggregate that causes expansion damage on the surface of the concrete component, and is characterized by comprising: Drilling a set of concrete core samples from the concrete components, wherein the concrete components are first-category concrete components that belong to the same category and have consistent damage degrees; Determining, by experiment, a first volume expansion rate and a second volume expansion rate of the set of drilled concrete core samples, 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; A steel slag aggregate equivalent model is set in a finite element calculation model of a concrete component to simulate the force exerted by the volume expansion of the steel slag aggregate on the concrete component, and the surface expansion damage specification is determined based on the force and the design specifications of the concrete component. The volume expansion rate of the steel slag aggregate equivalent model is the larger of the first volume expansion rate and the second volume expansion rate, and the design specifications are the concrete grade, concrete mix ratio, and / or steel density of the first type of concrete component.

2. The method for determining apparent damage of a concrete component according to claim 1, characterized in that: The first volume expansion ratio is determined based on the expansion ratio caused by the steel slag aggregate in the set of concrete core samples, and the second volume expansion ratio is determined based on the volume expansion caused by free calcium oxide in the steel slag aggregate.

3. The method for determining apparent damage of a concrete component according to claim 2, characterized in that: The first volume expansion ratio and the second volume expansion ratio are determined by the following steps: removing the steel slag aggregate from the set of concrete core samples, and determining an average content of the removed steel slag aggregate in the set of concrete core samples; making a prototype of a concrete component according to the average content, treating the prototype according to a first preset physical condition, and measuring a first volume expansion rate of the prototype; Determining a first content of free oxides in a portion of the steel slag aggregates removed by chemical titration, treating another portion of the steel slag aggregates removed by second preset physical conditions, determining a second content of free oxides in the another portion of the steel slag aggregates by chemical titration, and determining a second steel slag volume expansion rate of the steel slag aggregates based on a difference between the first content and the second content. Among them, the first preset physical condition includes: continuously curing the trial product for a first preset time in a constant temperature water bath environment at a first preset temperature; the second preset physical condition includes: continuously curing the other part of the steel slag aggregate for a second preset time in a second preset temperature and preset pressure environment.

4. The method for determining apparent damage of a concrete component according to claim 3, characterized in that: When determining the first volume expansion rate, a control piece is also produced for comparison with the trial piece, wherein the specifications of the control piece are consistent with the specifications of the concrete component, and the material used to produce the control piece does not include the steel slag aggregate that causes surface expansion damage of the concrete component; The first volume expansion rate is a volume expansion rate of the first prototype after being processed according to the first preset physical condition compared to the volume expansion rate of the second prototype after being processed according to the first preset physical condition.

5. The method for determining apparent damage of a concrete component according to claim 3, 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.

6. The method for determining apparent damage of a concrete component according to any one of claims 1 to 5, characterized in that: For a second type of concrete member in the concrete structure, wherein the second type of concrete member is a concrete member of the same category and with the same degree of damage, and is of a different category and / or has 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: Drilling a second set of concrete core samples from the second type of concrete components; Determining, by experiment, a first volume expansion rate and a second volume expansion rate of the second group of concrete core samples drilled; A steel slag aggregate equivalent model of the second type of concrete component is set in the concrete component finite element calculation model of the second type of concrete component to simulate a second force acting on the second type of concrete component by the volume expansion of the steel slag aggregate in the second type of concrete component. A surface expansion damage specification of the second type of concrete component is determined based on the second force and the design specification of the second type of concrete component.

7. A method for repairing apparent damage to a concrete component, characterized in that: include: The method for determining apparent damage of a concrete member according to any one of claims 1 to 6, 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 component to the depth is replaced with concrete that meets the repair requirements.

8. The method for repairing apparent damage of a concrete component according to claim 7, characterized in that: The set of concrete core samples drilled are determined based on the location of the apparent damage to be repaired.

9. A method for repairing apparent damage to a concrete structure, characterized in that: include: Selecting the first batch of concrete elements from the concrete structure to be repaired; as well as The method for repairing apparent damage to a concrete member according to claim 7 or 8, wherein the first batch of concrete members selected and removed are repaired. The selection conditions for the first concrete components are: belonging to the same production batch, belonging to the same construction batch, and / or being exposed to the same environmental conditions.

10. The method for repairing apparent damage of a concrete structure according to claim 9, characterized in that: Also includes: selecting 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 7 or 8, wherein the second batch of concrete components selected and removed are repaired. The selection conditions of the second concrete component are different from the selection conditions of the first concrete component.

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