JP2015010918A - Method for estimating durability of concrete - Google Patents

Abstract

A method for estimating the durability of concrete capable of estimating the durability of a concrete frame with high accuracy is provided.
In a method for estimating the durability of a reinforced concrete, the strength of the reinforced concrete at its original position is estimated, and the relationship between the strength of the concrete and the gel void ratio is obtained in advance, and this relationship and the strength at the original position are obtained. Based on the above, an index relating to the microscopic structure of the frame concrete is calculated. Furthermore, the durability of the frame concrete is estimated based on an index related to the microscopic structure of the frame concrete. In this method, not only the theoretically required index for the microscopic structure but also the index for the microscopic structure of the reinforced concrete is calculated by taking into account the strength of the reinforced concrete in situ. As a result, the durability of the concrete frame is estimated with high accuracy.
[Selection] Figure 1

Description

  The present invention particularly relates to a method for estimating the durability of concrete in situ.

  As factors that reduce the durability of concrete, for example, neutralization by carbon dioxide gas, salt damage by chloride ions, and the like are conceivable. These factors are deterioration factors that permeate into the concrete from the external environment. Due to such deterioration factors, the neutralization of the concrete proceeds and the durability decreases.

  Conventionally, as a method for estimating the progress of neutralization of concrete, as described in Non-Patent Document 1, there are a method using a simple formula and a method using numerical analysis as described in Non-Patent Document 2. Are known. Further, as a technique for predicting the progress of salt damage, a method using a simple formula as described in Non-Patent Document 1 and a method using numerical analysis as described in Non-Patent Document 3 are known. .

  On the other hand, a so-called in-situ estimation method is also known in which tests and evaluations are performed using the frame concrete itself. For example, as described in Non-Patent Document 4 below, a method of testing air permeability by a double chamber method or the like, or as described in Non-Patent Document 5, using a water permeability tester, Methods for testing are known. In these methods, durability is estimated by testing air permeability or water permeability.

Architectural Institute of Japan, Guidelines for Durability Design and Construction of Reinforced Concrete Buildings (Draft), Commentary, pp. 97-98, March 2004 For example, Tetsuya Ishida, et al., PH evaluation model for pore water based on mass transfer law and scientific equilibrium theory, JSCE V-47, pp. 203-215, 2000 For example, Yoshitomo Yamada et al., Analytical study on penetration of chloride ion in concrete under salt damage environment, Architectural Institute of Japan, Papers on Structural Systems, No. 501 pp. 13-18, 1997 Architectural Institute of Japan, Test Methods for Quality Control and Maintenance of Reinforced Concrete Buildings, March 2007 Japan Society of Civil Engineers, Concrete quality and durability performance verification system research subcommittee (335 committee) results report and symposium lecture summary collection, April 2008

  However, in the conventional method using a simple formula or numerical analysis, the durability estimation result is often different from the actual durability. It is considered that the durability of the frame concrete that actually forms the frame is influenced not only by the construction plan of the composition and materials used, but also by the factors such as the casting condition of the frame concrete, the curing method, or the external environment. However, these factors are often uncertain at the time of prediction, and it is difficult to create an analysis method that incorporates all the factors. Therefore, it is difficult to estimate the durability of the frame concrete with high accuracy.

  Of the conventional methods in-situ, for example, the double chamber method basically provides only a qualitative evaluation of quality (five-step evaluation from Very Good to Very Bad), and improves the durability of the concrete frame. It is difficult to estimate with high accuracy. In addition, in the air permeability test and the water permeability test, a large atmospheric pressure or a water pressure acts on the surface of the concrete, which is the measurement surface, on the measurement principle. For example, when there is a minute defect on the measurement surface, The measurement results are likely to vary due to the influence. Although it is conceivable to increase the number of measurement points in order to increase the reliability of data, it is difficult to increase the number of measurement points because the time required for measurement is long. Thus, with the conventional method, it was difficult to estimate the durability of the frame concrete with high accuracy.

  An object of the present invention is to provide a method for estimating the durability of concrete capable of accurately estimating the durability of the frame concrete.

  The method for estimating the durability of the concrete of the present invention includes a step of obtaining a relationship between the strength of the concrete and an index relating to the microscopic structure of the concrete, a step of estimating the strength at the original position of the frame concrete forming the frame, Based on the relationship and the strength of the concrete in situ, the process for calculating the index for the microstructure of the frame concrete and the durability of the frame concrete based on the index for the microstructure of the frame concrete And a step of performing.

  According to this method for estimating the durability of concrete, the strength at the original position of the frame concrete forming the frame is estimated. In addition, a relationship between the strength of the concrete and the index regarding the microscopic structure is obtained in advance, and the index regarding the microscopic structure of the concrete frame is calculated based on this relationship and the strength at the original position. Furthermore, the durability of the frame concrete is estimated based on an index related to the microscopic structure of the frame concrete. Since the index regarding the microscopic structure of concrete greatly affects the durability of concrete, the durability of the frame concrete can be estimated based on the index. Here, in the above-described method, not only the theoretically required index for the microscopic structure but also the index for the microscopic structure of the frame concrete is calculated by taking into account the strength at the original position of the frame concrete. Thereby, the index regarding the microscopic structure of the frame concrete is calculated more accurately, and as a result, the durability of the frame concrete can be estimated with high accuracy.

  In the above-described method, in the step of obtaining the relationship, the index regarding the microscopic structure calculated using the cement hydration reaction model and the specimen prepared using the same material as the concrete at the time of placing the concrete You may ask | require the relationship with intensity | strength. In this case, since the above relationship is required by using the strength of the specimen prepared using the same material as the concrete at the time of placing the concrete, the above relationship reflects the actual construction situation. Become. Therefore, the durability of the frame concrete can be estimated with higher accuracy.

  In the above method, in the step of estimating the strength at the original position, the UCI (Ultrasonic Contact Inpedance) method, which is a method for estimating the hardness of the concrete frame from the change in the resonance frequency before and after contacting the measurement sensor, may be used. The UCI method is a nondestructive test or a microdestructive test, is easy to perform on-site measurement, and requires only one measurement time. Therefore, many measurement points can be taken and the durability of the frame concrete can be estimated with higher accuracy. In addition, since the strength measurement using the UCI method is highly accurate, higher accuracy can be achieved.

  In the above method, the step of estimating the durability of the frame concrete includes the step of calculating the moisture content or the amount of calcium hydroxide of the frame concrete corresponding to the index related to the microscopic structure of the frame concrete, and the calculated moisture content or And a step of predicting the progress of neutralization of the frame concrete using calcium hydroxide. By predicting the progress of neutralization of the frame concrete, the durability of the frame concrete can be estimated quantitatively. Since the moisture content or the amount of calcium hydroxide used here is a numerical value corresponding to an index related to the microscopic structure of the frame concrete, the prediction accuracy of the progress of neutralization can be increased.

  In the above method, the step of estimating the durability of the frame concrete includes the steps of calculating the moisture content of the frame concrete corresponding to the index related to the microscopic structure of the frame concrete, and using the calculated moisture content, Predicting the diffusion of chloride ions at. By predicting the diffusion of chloride ions in the frame concrete, the durability of the frame concrete can be estimated quantitatively. Since the moisture content used here is a numerical value corresponding to an index related to the microscopic structure of the concrete frame, it is possible to improve the prediction accuracy of the diffusion of chloride ions.

  In the above method, the index related to the microscopic structure may be a gel void ratio. The gel void ratio is a volume ratio between a cement hydration product and voids, and is one of the indexes representing the compactness of the structure. The amount of voids in the reinforced concrete obtained from the gel void ratio affects the permeability of substances (carbon dioxide, chloride ions, etc.), so, for example, the progress of neutralization or the diffusion of chloride ions can be predicted with high accuracy. It is possible to estimate the durability of the concrete frame with higher accuracy.

  In the above method, the temperature and humidity inside the concrete is calculated when calculating the microscopic structural index using the cement hydration reaction model in the step of installing the temperature and humidity sensor inside the concrete and the step of obtaining the relationship. The method may further include a step of predicting a change with time and a step of monitoring the durability of the concrete by comparing the predicted temperature and humidity with the temperature and humidity measured by the temperature and humidity sensor. Based on the temperature and humidity inside the concrete, it is possible to estimate the microscopic structure, that is, the density of the structure. For example, if the interior of the skeleton concrete is drying faster than expected, the microscopic structure or structure may be rough and the quality of the skeleton concrete may be lower than expected. Thus, the durability of the frame concrete can be monitored by measuring the temperature and humidity inside the frame concrete.

  ADVANTAGE OF THE INVENTION According to this invention, durability of a frame concrete can be estimated with high precision.

It is a flowchart which shows one Embodiment of the estimation method of durability of concrete. It is a flowchart which shows in detail the estimation procedure shown by the flowchart of FIG. It is a flowchart which shows the estimation procedure following FIG. It is explanatory drawing of prediction of the physical-property value by the numerical analysis using a hydration reaction model. It is a graph which shows the relationship between the gel void | hole ratio by analysis to a numerical value, and the measured value of the compressive strength using a test body. (A) is a graph which shows the compressive strength of the frame concrete by a UCI method according to the water cement ratio of an estimation location, (b) is based on the compressive strength estimated by (a), and the relationship of FIG. It is a graph which shows an example which calculates | requires the gel space | gap ratio of frame concrete. It is a graph which shows the progress prediction of neutralization for every presumed location. It is a figure which shows schematic structure of a temperature / humidity monitoring apparatus. It is a flowchart which shows the monitoring procedure of durability of concrete. It is a figure which shows the relationship between the age of concrete and relative strength.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following description, a method for estimating the durability of the concrete frame based on the in situ and non-destructive / microdestructive strength estimation will be described. In the following description, the term “concrete” simply refers to general concrete, and the term “frame concrete” refers to concrete that is actually placed and forms a frame, that is, the object of durability estimation. Means concrete. In-situ strength estimation means estimation of the strength of the concrete frame itself. That is, in the method of the present embodiment, testing and evaluation (estimation of durability) are performed using reinforced concrete.

  1 to 3 are flowcharts showing a procedure of a method for estimating the durability of concrete. FIG. 1 shows a schematic procedure, and FIGS. 2 and 3 show a more detailed procedure. First, the relationship between the strength of concrete and the gel void ratio of concrete (an index related to the microscopic structure) is calculated (step S1). This gel void ratio is a volume ratio between the cement hydration product and voids, and is one of the indexes representing the compactness of the tissue.

  In step S1, first, when actually placing concrete in the field, a cylindrical specimen is prepared using the same material as the concrete (step S11). In this step S11, a plurality of cylindrical specimens are produced. The mixing conditions and materials used for these cylindrical specimens are the same as the mixing conditions and materials used for the frame concrete. In addition, it is not restricted to producing a cylindrical specimen, and may be a prismatic specimen. Subsequently, the cylindrical specimen is sealed and cured at the site (step S12).

  Thereafter, the cylindrical specimen is demolded (step S13). In this step S13, some of the cylindrical specimens are demolded at, for example, 7 days of age, and other of the cylindrical specimens are demolded at, for example, 28 days of age. That is, some specimens are demolded at a certain age, and some other specimens are demolded at an age different from that age. The age at which demolding is performed is not limited to 7 days and 28 days, and can be changed and set as appropriate.

  Furthermore, the compression strength in each material age is measured regarding the cylindrical specimen which performed mold removal (step S14). In this step S14, for example, the compressive strength of the cylindrical specimen may be measured by a nondestructive / microdestructive test such as UCI (Ultrasonic Contact Inpedance) method or repulsion degree method, but not limited to the nondestructive / microdestructive test. The compressive strength of the cylindrical specimen may be measured by a method of collecting the core from the concrete frame.

  Next, the gel void ratio is estimated by numerical analysis (step S15). In this step S15, the gel void ratio of the specimen at an arbitrary time is estimated using a cement hydration model. More specifically, as shown in FIG. 4, the cement condition is determined based on design conditions such as concrete preparation (water cement ratio), construction materials such as materials used, curing period and curing method, and environmental conditions such as environmental temperature and humidity. The hydration reaction is calculated, and the gel void ratio of the specimen at an arbitrary time is estimated. In addition, it is not restricted to the gel space | gap ratio in arbitrary time, You may estimate the other parameter | index regarding the durability of concrete, for example, a porosity.

As shown in FIG. 4, in the process of numerical analysis in step S15, in addition to the gel void ratio, the amount of calcium hydroxide (Ca (OH) ₂ amount), the temperature and humidity, and the amount of moisture (or moisture content), etc. A calculation result is obtained. Therefore, these calculation results are recorded and stored in a separate memory or file.

  Next, the relationship between the strength of the cylindrical specimen and the gel void ratio of the cylindrical specimen is calculated (step S16). In this step S16, the gel void ratio of the specimen at the arbitrary time estimated in step S15 is taken on the horizontal axis, and the compressive strength of the cylindrical specimen at each age measured in step S14 is taken on the vertical axis. The relationship between the strength of the specimen and the gel void ratio is plotted on a graph (see FIG. 5). More specifically, the theoretical gel void ratio with respect to the strength of the cylindrical specimen is obtained by matching the age of the cylindrical specimen whose strength was measured in step S14 with an arbitrary time according to the numerical analysis method in step S15. calculate.

As a result of the calculation process in step S16, an approximate expression is obtained as shown in FIG. That is, the coefficient a and the coefficient b in the case of expressing the relationship between the concrete strength and the microscopic structure, for example, f (x) = ax ^b as an approximate expression are calculated. As a result, an approximate curve of f (x) = ax ^b is obtained.

The process of the above step S11-step S16 is corresponded to the process of step S1 which calculates the relationship between the intensity | strength of concrete and the gel void | hole ratio of concrete. In other words, the processing of step S11 to step S16 corresponds to a step of obtaining a relationship between the strength of concrete and an index related to the microscopic structure of concrete. Note that the relationship between the strength of concrete and the index related to the microscopic structure of the concrete is not limited to the case represented by f (x) = ax ^b . The approximate expression of f (x) = ax ^b is merely an example representing the relationship between the strength of concrete and an index related to the microscopic structure of concrete. Since there is an inverse relationship between the strength of concrete and the porosity, various other relational expressions can be used. The period during which the process of step S1 (the process of step S11 to step S16) is carried out is approximately 28 days to 1 month, although it varies depending on the timing of demolding in step S13 and the measurement of the compressive strength in step S14. . In FIG. 2, this period is shown as the first period.

  On the other hand, as shown in FIG. 1, the strength of the concrete in the original position is estimated (step S2). More specifically, as shown in FIG. 2, while step S11 to step S16 are performed, the concrete frame is placed on site (step S21). After the concrete is cast and a predetermined period has elapsed, demolding is performed (step S22). These processes are a part of the actual construction process of structures such as buildings.

  Subsequently, as shown in FIG. 3, after the mold is removed and a predetermined period has elapsed, the surface strength of the concrete is estimated by a nondestructive / microdestructive test (step S <b> 23). In this step S23, for example, the UCI method, which is a method for estimating the hardness of the concrete frame from the change in the resonance frequency before and after contacting the measurement sensor, is used. With the UCI method, when a rod that vibrates at a constant frequency is brought into contact with the material to be measured, the frequency changes according to the indentation area and the elastic modulus, and the indentation area is calculated backward from the change in frequency. This is a technique for estimating hardness (= load / indentation area). Actually, measurement is performed by pressing the tip of the rod with Vickers diamond against the material to be measured.

  In more detail, in the UCI method, the thickness is such that the indentation area is constant between the surface of the concrete frame and the rod, and the thickness can be secured to the extent that the concrete is not indented. Measurement is performed by inserting a thin insertion material of the product, and the elastic modulus is determined from the change in the frequency by using the correlation between the prepared frequency and the elastic modulus. A specific method of intensity estimation using the UCI method is disclosed in, for example, Japanese Patent Application No. 2011-284868.

  FIG. 6A is a graph showing the compressive strength of the frame concrete by the UCI method according to the water cement ratio at the estimated location. In the example shown in FIG. 6 (a), the compressive strength is estimated for three concrete frames having different water-cement ratios. Normally, the higher the water cement ratio, the lower the compressive strength of the concrete. However, in the example shown in FIG. 6 (a), the water cement ratio is higher than the compressive strength of the reinforced concrete with a water cement ratio of 55 (%). The compressive strength of 65% concrete is slightly higher. The compressive strength of the reinforced concrete with a water cement ratio of 65 (%) is almost equal to the compressive strength of the reinforced concrete with a water cement ratio of 45 (%). As described above, by estimating the strength of the concrete in the original position, a result different from the tendency simply assumed from the water cement ratio can be obtained.

  The process in step S23 corresponds to a process for estimating the strength of the concrete in the original position. The process in step S23 is performed after the process in step S1, that is, after the first period has elapsed. In FIG. 3, this period is shown as the second period.

Subsequently, as shown in FIG. 1, estimation of the gel void ratio of the frame concrete in the original position is performed (step S3). That is, as shown in FIG. 3, the gel void ratio of the concrete frame is estimated (step S31). In this step S31, the compression strength (that is, f (x)) in the relationship between the strength of the cylindrical specimen calculated in step S16 and the gel void ratio of the cylindrical specimen (that is, f (x) = ax ^b described above) The compressive strength of the concrete frame estimated in S23 is substituted (see FIG. 6B). By this process, the gel void ratio estimated in step S15 is recalculated, and the gel void ratio corresponding to the actual concrete frame is calculated.

  As described above, by using the strength of the concrete frame estimated at the original position, it is possible to estimate the gel void ratio in accordance with the actual situation. The process of step S31 corresponds to a step of calculating an index related to the microscopic structure of the frame concrete based on the above relationship and the strength of the frame concrete at the original position.

  Next, as shown in FIG. 1, the durability of the frame concrete is estimated (step S4). More specifically, as shown in FIG. 3, the moisture content, the amount of calcium hydroxide, the temperature and humidity, etc. of the concrete frame are calculated by numerical analysis (step S41). Here, assuming that the gel void ratio obtained in step S31 is the true value of the frame concrete, each value corresponding to the gel void ratio separately stored in step S15 is read. Step S41 corresponds to a step of calculating the moisture content or the amount of calcium hydroxide of the frame concrete corresponding to the index related to the microscopic structure of the frame concrete.

  Subsequently, the progress of neutralization of the frame concrete is predicted (step S42). In this step S42, the progress of neutralization is predicted using the existing literature. For example, refer to the “Nippon Architectural Institute of Japan, Guidelines for Durability Design and Construction of Reinforced Concrete Buildings (draft) / Explanation, pp. 97, 109” mentioned above in Non-Patent Document 1 to predict the progress of neutralization. Can do. In addition, in order to predict the progress of neutralization, water content and calcium hydroxide are required. This step S42 corresponds to a step of predicting the progress of neutralization of the frame concrete using the calculated moisture content or calcium hydroxide.

  FIG. 7 is a graph showing the prediction of neutralization progress for each estimated location. In FIG. 7, the curve with the largest neutralization depth (deep) shows the prediction of the neutralization progress of the concrete with a water cement ratio of 65 (%), and then the neutralization depth is deep (deep) ) Curve shows the progress of neutralization of the concrete with 55% water cement ratio, and the curve with the smallest neutralization depth (shallow) shows that of the concrete with 45% water cement ratio. The prediction of neutralization progress is shown.

  In addition, it is not restricted to predicting the progress of neutralization as in step S42, and the diffusion of chloride ions in the concrete may be predicted using the calculated moisture content. In this case, the existing literature “Isao Ujiie, Masahisa Kakizaki, Shigeyoshi Nagahama, Research on the air permeability of concrete and the diffusion of oxygen and chlorine ions, Annual report on concrete engineering, Vol.15, No.4 Pp. 519-524, 1993 "can be used to predict the diffusion of chloride ions.

  The processing of step S41 and step S42 corresponds to a step of estimating the durability of the frame concrete.

  Then, it is determined whether the frame concrete satisfies the service period (step S43). When it is determined in step S43 that the concrete frame satisfies the service period (step S43; Yes), the series of processes ends. If it is determined in step S43 that the frame concrete does not satisfy the service period (step S43; No), some measures are applied to the frame concrete.

  According to the estimation method of the durability of the frame concrete described above, the strength at the original position of the frame concrete forming the frame is estimated. In addition, a relationship between the strength of concrete and an index related to the microscopic structure (specifically, the gel void ratio) is obtained in advance, and based on this relationship and the strength in situ, the microscopic structure of the concrete frame An indicator is calculated. Furthermore, the durability of the frame concrete is estimated based on an index related to the microscopic structure of the frame concrete. Since the index regarding the microscopic structure of concrete greatly affects the durability of concrete, the durability of the frame concrete can be estimated based on the index. Here, in the above-described method, not only the theoretically required index for the microscopic structure but also the index for the microscopic structure of the frame concrete is calculated by taking into account the strength at the original position of the frame concrete. Thereby, the index regarding the microscopic structure of the frame concrete is calculated more accurately, and as a result, the durability of the frame concrete can be estimated with high accuracy. For example, if a nondestructive test or microdestructive test that can easily measure the strength of the concrete in situ is adopted, a large number of measurement points can be taken, and the durability of the concrete can be estimated with higher accuracy. .

  In addition, since the above relationship is required by using the strength of the specimen prepared using the same material as the concrete at the time of placing the concrete, the above relationship reflects the actual construction situation. . Therefore, the durability of the frame concrete can be estimated with higher accuracy.

  Further, in the step of estimating the strength at the original position, the UCI method, which is a method for estimating the hardness of the concrete frame from the change in the resonance frequency before and after contacting the measurement sensor, is used. The UCI method is a nondestructive test or a microdestructive test, is easy to perform on-site measurement, and requires only one measurement time. Therefore, many measurement points can be taken and the durability of the frame concrete can be estimated with higher accuracy. In addition, since the strength measurement using the UCI method is highly accurate, higher accuracy can be achieved.

  Moreover, the durability of the frame concrete can be quantitatively estimated by predicting the progress of neutralization of the frame concrete. Since the moisture content or the amount of calcium hydroxide used here is a numerical value corresponding to an index related to the microscopic structure of the frame concrete, the prediction accuracy of the progress of neutralization can be increased.

  It should be noted that the durability of the reinforced concrete can also be quantitatively estimated by predicting the diffusion of chloride ions in the reinforced concrete. Since the moisture content is a numerical value corresponding to an index related to the microscopic structure of the frame concrete, it is possible to improve the prediction accuracy of the diffusion of chloride ions.

  In addition, the amount of voids in the concrete obtained from the gel void ratio affects the permeability of substances (carbon dioxide, chloride ions, etc.). For example, the progress of neutralization or the diffusion of chloride ions is highly accurate. Therefore, the durability of the concrete frame can be estimated with higher accuracy.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, the present invention provides a method for calculating an index related to a microscopic structure using a cement hydration reaction model in a step of installing a temperature and humidity sensor inside a concrete frame and a step of obtaining the above relationship. There may be further included a step of predicting a change in temperature and humidity with time and a step of monitoring the durability of the concrete by comparing the predicted temperature and humidity with the temperature and humidity measured by the temperature and humidity sensor.

  More specifically, the monitoring device 1 can be installed when placing concrete in the concrete. As shown in FIG. 8, the monitoring device 1 includes a wireless temperature sensor device 10 attached to the mold 11 and a data browsing device that receives a signal transmitted from the wireless temperature sensor device 10 and enables data browsing. 20. The wireless temperature sensor device 10 includes a temperature detection unit 13 fixed to a reinforcing bar 12 disposed in a mold 11 and a transmission main body unit 14 connected to the temperature detection unit 13 by a data transmission cable 15. The transmission main body unit 14 includes a wireless antenna 16, a battery 17, a data memory 18, and a data processing unit 19. On the other hand, the data browsing device 20 that is capable of wireless communication with the transmission main body 14 includes a wireless antenna 21, a data browsing unit 22, a data memory 23, and an external output terminal 24.

  In this monitoring device 1, first, the wireless temperature sensor device 10 is installed inside the concrete frame. Next, as shown in FIG. 9, the temperature and humidity inside the concrete frame are predicted by numerical analysis (step S51). Here, the temperature and humidity stored in step S15 can be used. Next, after concrete placement (step S21), the temperature and humidity inside the concrete frame using the wireless temperature sensor device 10 is monitored (step S52). Next, the temperature / humidity predicted by numerical analysis is compared with the measured value of temperature / humidity obtained by temperature / humidity monitoring (step S53). And it is determined whether the predicted value of temperature and humidity by numerical analysis and the measured value have deviated (step S54). If it is determined in step S54 that the predicted value does not deviate from the actual measurement value (step S54; No), the process returns to the monitoring in step S52. If it is determined that the predicted value and the actual measurement value are deviated in step S54 for the concrete frame (step S54; Yes), some measures are taken. The frequency of performing the series of monitoring processes can be set as appropriate. For example, the frequency may be once every several weeks or once every several months.

  In the monitoring by the monitoring device 1, the microscopic structure, that is, the density of the structure can be estimated based on the temperature and humidity inside the concrete. For example, as shown in FIG. 10, the actual change in temperature and humidity with time varies from one concrete to another. For example, when the inside of the concrete is drying faster than expected, the microscopic structure, ie, the structure is rough. It is considered that the quality of the concrete frame is lower than expected. Thus, the durability of the frame concrete can be monitored by measuring the temperature and humidity inside the frame concrete.

  The above step S51 corresponds to a step of predicting a temporal change in temperature and humidity inside the concrete when calculating an index related to the microscopic structure using a cement hydration reaction model in the step of obtaining the above relationship. Steps S53 and S54 correspond to a process of monitoring the durability of the concrete frame by comparing the predicted temperature and humidity with the temperature and humidity measured by the temperature and humidity sensor.

  In the above embodiment, in steps S11 to S16, the gel void ratio calculated using the cement hydration reaction model, and the strength of the specimen prepared using the same material as the concrete at the time of placing the concrete However, the present invention is not limited to this, and the relationship between the strength and the index may be obtained based on a relationship already obtained by another method (for example, a past document).

  In the above embodiment, the method of estimating the in-situ strength of the frame concrete by the UCI method in step S23 has been described. However, the compressive strength of the cylindrical specimen is measured by another nondestructive / microdestructive test such as the repulsion degree method. In addition, the compressive strength of the cylindrical specimen may be measured by a method of collecting the core from the concrete without being limited to the nondestructive / microdestructive test.

Moreover, in the said embodiment, although the gel space | gap ratio was mentioned as a parameter | index regarding the micro structure of concrete, it is not restricted to a gel space | gap ratio, For example, a cement space | gap ratio etc. may be sufficient. The cement void ratio is an index represented by Fc = A + B (c / v), where Fc: cement void ratio, c: absolute volume of cement, v: volume of unit water volume and 1 m ^{3 of} concrete. Sum with volume of air, A, B: constants.

  DESCRIPTION OF SYMBOLS 1 ... Monitoring apparatus, 10 ... Wireless temperature sensor apparatus (temperature / humidity sensor).

Claims (7)

Obtaining a relationship between the strength of the concrete and an index on the microscopic structure of the concrete;
Estimating the in-situ strength of the frame concrete forming the frame;
Based on the relationship and the strength at the original position of the frame concrete, calculating an index related to the microscopic structure of the frame concrete;
A step of estimating the durability of the frame concrete based on an index relating to the microscopic structure of the frame concrete;
A method for estimating the durability of concrete, comprising: In the step of obtaining the relationship, an index related to the microscopic structure calculated using a hydration reaction model of cement, and a specimen manufactured using the same material as the concrete at the time of placing the concrete Find the relationship with strength,
The method for estimating the durability of concrete according to claim 1. In the step of estimating the strength at the original position, a UCI (Ultrasonic Contact Inpedance) method, which is a method for estimating the hardness of the concrete frame from a change in resonance frequency before and after contact with the measurement sensor, is used.
The method for estimating durability of concrete according to claim 1 or 2. The step of estimating the durability of the concrete frame is as follows:
Calculating the moisture content or the amount of calcium hydroxide of the concrete, corresponding to an indicator relating to the microscopic structure of the concrete;
Using the calculated moisture content or calcium hydroxide, predicting the progress of neutralization of the reinforced concrete, and
The estimation method of durability of the concrete as described in any one of Claims 1-3. The step of estimating the durability of the concrete frame is as follows:
A step of calculating a moisture content of the frame concrete corresponding to an index relating to a microscopic structure of the frame concrete;
Using the calculated moisture content, predicting the diffusion of chloride ions in the concrete frame,
The estimation method of durability of the concrete as described in any one of Claims 1-4. The indicator for the microscopic structure is a gel void ratio,
The method for estimating durability of concrete according to any one of claims 1 to 5. Installing a temperature and humidity sensor inside the concrete frame;
A step of predicting a temporal change in temperature and humidity inside the concrete when calculating an index relating to the microscopic structure using a hydration reaction model of cement in the step of obtaining the relationship;
The method for estimating the durability of the concrete according to claim 2, further comprising: monitoring the durability of the frame concrete by comparing the predicted temperature and humidity with the temperature and humidity measured by the temperature and humidity sensor. .

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