Cement mixture air content prediction method and cement mixture air content prediction system

Abstract

To provide a technique that enables non-contact prediction of cement mixture air content regardless of skills of measurers.SOLUTION: A cement mixture air content prediction method is provided, comprising irradiating an uncured cement mixture with light to measure reflectance of the light irradiated on the cement mixture using a reflectometer, and predicting air content of the cement mixture on the basis of the measured reflectance.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a technique for predicting the air content of a cement mixture such as fresh concrete. [Background technology]

[0002] Four evaluation values ​​are known for evaluating the quality of cement mixtures such as fresh concrete: strength, slump or slump flow, air content, and chloride content. Concrete is made up of materials including water, cement, sand, and gravel, but also air. The air content of concrete affects the workability during concrete pouring, freeze-thaw resistance, strength, and other properties, so it is important that the air content of concrete is appropriate.

[0003] Known methods for measuring the air content in concrete include the air chamber pressure method (JIS A 1128: Test method for air content in fresh concrete by pressure), the mass method (JIS A 1116: Test method for unit volume mass of fresh concrete and test method for air content by mass), and the volumetric method (JIS A 1118: Test method for air content in fresh concrete by volume). However, these measurement methods require taking samples of concrete after mixing and conducting the measurement, which requires a certain level of skill. Therefore, it would be desirable to be able to predict the air content without contacting the concrete, regardless of the skill of the person making the measurement.

[0004] Patent Document 1 discloses a machine learning technique for predicting the quality of concrete based on images of the concrete being mixed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6680936 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a technology that can predict the air content of a cement mixture in a non-contact manner, without relying on the skill of the measurer. [Means for solving the problem]

[0007] The method for predicting the air content of a cement mix disclosed herein includes the steps of irradiating an unhardened cement mix with light and measuring the reflectance of the light irradiated onto the cement mix with a reflectometer, and predicting the air content of the cement mix based on the measured reflectance.

[0008] The system for predicting the air content of a cement mix disclosed herein includes a light source that irradiates light onto an unhardened cement mix, a reflectometer that measures the reflectance of the light irradiated onto the cement mix, and a prediction unit that predicts the air content of the cement mix based on the measured reflectance. [Effects of the Invention]

[0009] According to the present disclosure, the use of a reflectometer makes it possible to predict the air content of an unhardened cement mixture without contacting the material. Furthermore, the prediction is possible without relying on the skill of the person performing the measurement. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a flowchart showing a method for predicting the air content of an unhardened cement mix according to the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the configuration of a system for predicting the air content of a cement mix, which executes the method described in FIG. 1. [Figure 3] 1 is a graph showing the change in reflectance of concrete during mixing in a mixer. [Figure 4] FIG. 1 is a diagram showing the relationship between the air content (actually measured value) and the reflectance (actually measured value) of concrete. [Figure 5] FIG. 10 is a diagram showing the results of predicting the air contents of concretes A to G based on the generated approximate formula. [Figure 6]10 is a graph showing the relationship between the measured air volume and the predicted air volume for a number of examples. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] The prediction method of this embodiment includes the steps of irradiating an unhardened cement mixture with light and measuring the reflectance of the light irradiated onto the cement mixture with a reflectometer, and predicting the air content of the cement mixture based on the measured reflectance. Reflectance varies depending on the unevenness of an object. The air content of a cement mixture such as concrete varies depending on the blend ratio, and the surface properties also vary depending on the air content. Therefore, the air content is estimated from the reflectance of the surface of the cement mixture such as concrete.

[0013] This method uses a reflectometer, making it possible to predict the air content of unhardened cement mixes without contacting the material. Furthermore, this prediction is independent of the skill of the person performing the measurement.

[0014] Examples of the unhardened cement mixture include fresh concrete and fresh mortar. The reflectance can be measured with a reflectometer at various times during or after mixing, such as when the materials are being mixed in a mixer, when the materials are stored in a hopper or the like after mixing is complete, when the materials are being loaded into an agitator car after mixing is complete, and when the materials are being unloaded from the agitator car using a chute or the like.

[0015] In the following embodiment, as shown in Fig. 2, an example will be described in which the prediction target is fresh concrete at the stage of mixing materials in a mixer 10. Fig. 1 is a flowchart showing the method for predicting the air content of an unhardened cement mix according to the present disclosure. Fig. 2 is a block diagram showing the configuration of a system for predicting the air content of a cement mix that executes the method shown in Fig. 1. The prediction method and prediction system will be described below with reference to Figs. 1 and 2.

[0016] (Measurement step) In step ST1 shown in FIG. 1, light is irradiated from light source 11 onto the cement mixture being mixed in mixer 10, and the reflectance of the light irradiated onto the cement mixture is measured by reflectometer 12. Reflectance measurements are performed continuously at multiple points during mixing. FIG. 3 is a graph showing the change in reflectance of concrete being mixed in mixer 10. In the example of FIG. 3, reflectance is measured from the start of mixing (T0) to the discharge point (T2) of the fresh concrete, but reflectance may also be measured for a predetermined period starting from the start of mixing (T0) or the discharge point (T2). As shown in FIG. 3, it can be seen that after all the ingredients (cement, aggregate, and water) have been added, the reflectance converges as mixing progresses.

[0017] As shown in FIG. 2, the mixer 10 has a mixing chamber 10a in which the cement mixture is mixed. The mixing chamber 10a is a dark place. The dark place is preferably a place completely shielded from external light, but may also be a place where some external light enters. If some external light enters the mixing chamber 10a, the dark place should be one in which the light from the light source 11 disposed at the top of the mixer 10 dominates the measurement results and the external light does not affect the measurement results. The upper part of the mixer 10, i.e., the upper part of the mixing chamber 10a, contains a light source 11 that irradiates the cement mixture in the mixing chamber 10a with light, and a reflectometer 12 that measures the reflectance of the light irradiated onto the cement mixture by the light source 11. The light source 11 is positioned so that it can uniformly illuminate the entire cement mixture in the mixing chamber 10a. One or more light sources 11 can be provided, and the number of light sources 11 can be changed as needed. The reflectometer 12 receives all light within its detectable range and outputs the reflectance. The reflectometer 12 can use any method, such as a direct reflection method or an indirect reflection method. The angle of the detection port of the reflectometer 12 relative to the horizontal direction is set to be the same as the angle of the main irradiation direction of the light source 11 relative to the horizontal direction. The mixer 10 in this embodiment is a forced twin-shaft mixer having two horizontal shafts, but this is merely an example, and the mixer to which the present invention can be applied is not limited to this. For example, a Zycross type mixer in which no shaft (axis) is disposed inside the mixing chamber may be used. The effects of the present invention can be achieved regardless of the type of mixer as long as the mixer is configured to irradiate light uniformly or substantially uniformly onto the liquid surface of the cementitious mixture from above.

[0018] (Prediction step) In step ST2 following step ST1 shown in FIG. 1, a statistical value of reflectance is calculated based on multiple reflectances continuously measured at multiple points in time. The calculated statistical value is used to predict the air volume. The statistical value of reflectance may be the average value, mode value, median value, maximum value, minimum value, final value, or other statistical value. As shown in FIG. 3, the reflectance of the cement mix is ​​subject to pulsating changes, so it is preferable to perform statistical processing.

[0019] The average value is the sum of all reflectance values ​​divided by the desired measurement time. The mode is the most frequent value of the reflectance per unit time during any measurement time. The median is the value that is the middle of the ranking when the reflectances at any measurement time are arranged in order from the smallest to the largest. The maximum value is the highest value when the reflectances at any measurement time are arranged in order from smallest to largest. The minimum value is the smallest value when the reflectances at any measurement time are arranged in order from smallest to largest. The final value is the reflectance value that is acquired last in the reflectance measurement. This may be the entire measurement time, or only the time from when the convergence condition is satisfied until the fresh concrete is discharged. Among these, it is desirable to use the average value and the mode value, because the cementitious mixture is agitated by the rotation of the mixer blades during mixing, and therefore, evaluation of the properties using multiple reflectance data is more accurate than evaluation of the properties using only one reflectance data. It is also desirable to use the final value, because the value at the moment when the cementitious mixture is discharged from the mixer is closest to the properties of the concrete.

[0020] As shown in Figure 3, as mixing of the cement mixture progresses, the reflectance converges to a true value representing the air content. Therefore, among the multiple measured reflectances, at least one reflectance that satisfies a convergence condition may be used to predict the air content. Satisfying the convergence condition can be achieved under various conditions, such as when the amount or rate of change in reflectance per unit time is equal to or less than a predetermined threshold, when the mixing time has reached a predetermined time, or when the change in reflectance is judged to have converged by a human observer. One or more reflectances measured when the convergence condition is satisfied may be used for the prediction. Alternatively, one or more reflectances measured after the convergence condition is satisfied may be used for the prediction. Alternatively, one or more reflectances measured around the time the convergence condition is satisfied may be used for the prediction.

[0021] Furthermore, as shown in FIG. 3, as the mixing of the cement mixture progresses, the point at which the reflectance converges becomes more or less fixed. Therefore, as shown in the same figure, it is desirable to predict the air content using at least one reflectance measured between the first time point T1 and the second time point T2. The second time point T2 is the time when the cement mixture is discharged by the mixer. The first time point T1 is a predetermined time W1 before the second time point T2. In particular, using statistical values ​​(average value, mode) within a predetermined range (T1 to T2) set after the reflectance satisfies the convergence condition is particularly effective for improving accuracy. This is because, as shown in FIG. 3, the period immediately after the start time T0 is immediately after the materials are added, and the materials are not uniformly mixed. Therefore, the measured values ​​do not reflect the properties of the fresh concrete that are intended to be detected. Furthermore, during the period immediately after the start time T0, cement dust may be generated within the mixer 10, affecting light transmission, and the measured values ​​do not reflect the properties of the fresh concrete that are intended to be detected. After a certain period of time has passed in the mixing process, the properties of the fresh concrete will stabilize and the dust will subside, so the measured values ​​will approach values ​​that reflect the properties of the fresh concrete that we are actually trying to detect.

[0022] In step ST3 following step ST2 shown in FIG. 1, the air content is predicted based on the reflectance. Specifically, correlation data 20 correlating the air content and reflectance of the unhardened cement mix is ​​used to identify the air content corresponding to the measured reflectance as a predicted value. The correlation data 20 may be any data correlating the air content and reflectance. For example, the correlation data 20 may be an approximate equation generated based on multiple measured data including measured reflectances and measured air contents, or a prediction model generated by machine learning to output the air content using reflectance as input data. FIG. 4 is a diagram showing the relationship between the air content (measured value) and reflectance (measured value) of concrete. FIG. 4 shows plotted measured data and an approximate equation generated by fitting the plotted points using the least squares method. FIG. 5 is a diagram showing the results of predicting the air content of concretes A to G based on the generated approximate equation. FIG. 6 is a graph showing the relationship between the measured air content (%) and the predicted air content (%) for a number of examples. From Figure 6, it can be seen that the predicted air volume has little variation compared to the actually measured air volume, and that the prediction is good.

[0023] (Prediction System) The prediction method may be performed by a person or, as shown in FIG. 2, may be performed by a system. As shown in FIG. 2, the system for predicting the air content of a cement mix includes a light source 11 that irradiates an unhardened cement mix with light, a reflectometer 12 that measures the reflectance of the light irradiated on the cement mix, and a prediction unit 21 that predicts the air content of the cement mix based on the measured reflectance. The prediction system is configured to store correlation data 20 or to acquire it externally via a network. The prediction system includes an acquisition unit that acquires the reflectance measured by the reflectometer 12. The prediction unit 21 is realized by one or more processors of a computer reading a predetermined program. The prediction unit 21 includes a reflectance determination unit 22 and an air content determination unit 23. The correlation data 20 is an approximation formula shown in FIG. 4. The reflectance determination unit 22 determines a statistical value of reflectance based on multiple reflectances measured by the reflectometer 12 at multiple time points. The air content determination unit 23 uses the correlation data 20 to determine, as a predicted value, the air content corresponding to the statistical value of reflectance. This allows the system to automatically predict the air content of the cement mix. A display unit may be provided to display the prediction results by the prediction unit 21. Examples of the display unit include a display of a terminal such as a computer or a smartphone.

[0024] [Another embodiment] (A) In the above embodiment, the reflectance of concrete (cement mixture) is measured during mixing in the mixer 10, but this is not limiting. For example, the reflectance may be measured at the time when mixing is completed and the concrete is stored in a hopper or the like, or when mixing is completed and the concrete is being loaded into an agitator vehicle.

[0025] (B) The orientation of the reflectometer 12 and the light source 11 can be changed as appropriate.

[0026] (C) In the above embodiment, statistical processing is performed on multiple reflectances measured at multiple time points to calculate a single statistical value, but it is also possible to measure a single reflectance at a predetermined time point and use that single reflectance as is for prediction without performing statistical processing.

[0027] (D) The prediction system may not have the light source 11 and the reflectometer 21, but may have only the prediction unit 21. Alternatively, the prediction system may have the prediction unit 21 and a display unit.

[0028] [1] As described above in the above embodiment, the method for predicting the air content of a cement mix may include the steps of irradiating light onto an unhardened cement mix and measuring the reflectance of the light irradiated onto the cement mix using a reflectometer 12, and predicting the air content of the cement mix based on the measured reflectance. In this way, by using the reflectometer 12, it is possible to predict the air content of the unhardened cement mixture without contacting it, and it is also possible to make a prediction that is not dependent on the skill of the person performing the measurement.

[0029] [2] The method for predicting the air content of a cement mix described in [1] above may use correlation data 20 that associates the air content of an unhardened cement mix with reflectance, and identify the air content corresponding to the measured reflectance as a predicted value. Since the correlation data 20 that associates the air content and reflectance of the unhardened cement mixture is used, more accurate prediction may be possible.

[0030] [3] The method for predicting the air content of a cement mix according to the above [1] or [2] may include continuously measuring the reflectance at multiple points in time, calculating statistical values ​​of the reflectance based on the multiple reflectances measured at the multiple points in time, and predicting the air content based on the statistical values ​​of the reflectance. Since the statistical values ​​of multiple reflectances measured at multiple points in time are used, it may be possible to remove outliers, etc., thereby improving prediction accuracy.

[0031] [4] The method for predicting the air content of a cement mix described in [3] above may involve measuring the reflectance of the cement mix at multiple points in time while it is being mixed by the mixer 10 using the reflectometer 12, and predicting the air content based on at least one reflectance that satisfies the convergence condition among the reflectances at the multiple points in time. Since the air volume is predicted based on the reflectance that satisfies the convergence condition, the reflectance in a state where mixing is more complete can be used, thereby further improving the prediction accuracy.

[0032] [5] The method for predicting the air content of a cement mix described in [3] above may involve measuring the reflectance of the cement mix at multiple points in time using a reflectometer 12 while it is being mixed by a mixer 10, and predicting the air content using at least one reflectance measured between a first point in time T1, which is a predetermined time W1 before a second point in time T2 at which the cement mix is ​​discharged by the mixer 10, and a second point in time T2. The discharge time and the time when mixing is completed can be determined empirically depending on the materials and amount of the cement mixture, and the reflectance at the time when mixing is progressing and converging (T1 to T2) can be used based on the empirical rule, thereby further improving prediction accuracy.

[0033] [6] In the method for predicting the air content of a cement mixture described in [4] or [5] above, the mixer 10 may have a light source 11 that irradiates light onto the cement mixture in the mixing chamber 10a, which is a dark place, and a reflectometer 12 that measures the reflectance of the light irradiated onto the cement mixture by the light source 11. Since the reflectance is measured by irradiating light in the kneading chamber 10a in a dark place, the accuracy of the reflectance can be improved, and the prediction accuracy can be further improved.

[0034] [7] As in the above embodiment, the system for predicting the air content of a cement mixture may include a prediction unit 21 that predicts the air content of the cement mixture based on the reflectance of light irradiated onto the unhardened cement mixture (measured by a reflectometer 12), and a display unit that displays the prediction results by the prediction unit 21. This allows the system to automatically predict the amount of air in the cement mix.

[0035] [8] The present invention can also be specified as a computer program invention. That is, the program may cause one or more processors to acquire the reflectance of light irradiated onto an unhardened cement mixture, measured by a reflectometer, and predict the air content of the cement mixture based on the acquired reflectance. By executing a program having such a function, it becomes possible to automatically predict the amount of air in the cement mixture. The program may cause one or more processors to execute the following: using correlation data relating the air content and reflectance of the unhardened cement mix to determine the air content corresponding to the measured reflectance as a predicted value. The program may cause one or more processors to calculate a statistical value of reflectance based on multiple reflectances continuously measured at multiple points in time, and predict the amount of air based on the statistical value of reflectance. The reflectances at multiple points in time are measured reflectances of the cement mixture being mixed by a mixer, and the program may cause one or more processors to predict the air content based on at least one reflectance among the reflectances at multiple points in time that satisfies a convergence condition. The reflectances at multiple points in time are measured as reflectances of the cement mixture being mixed by the mixer, and the program may cause one or more processors to predict the air content using at least one reflectance measured from a first point in time to a second point in time that is a predetermined time before the second point in time at which the cement mixture is discharged by the mixer.

[0036] Although the embodiments of the present disclosure have been described above with reference to the drawings, the specific configurations should not be considered to be limited to these embodiments. The scope of the present disclosure is defined not only by the description of the above embodiments but also by the claims, and further includes all modifications within the meaning and scope of the claims.

[0037] The structures employed in the above-described embodiments can be employed in any other embodiment. The specific configurations of the components are not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure. [Explanation of symbols]

[0038] 10: Mixer 10a: Mixing chamber 11:Light source 12:Reflectance meter 20: Correlation data 21: Prediction section T1: Time point 1 T2: Time point 2 W1: Predetermined time

Claims

1. a step of irradiating an unhardened cement mixture with light and measuring the reflectance of the light irradiated onto the cement mixture with a reflectometer; and predicting the air content of the cement mix based on the measured reflectance.

2. 2. The method for predicting the air content of a cement mix according to claim 1, wherein correlation data relating the air content and reflectance of the unhardened cement mix is ​​used to identify the air content corresponding to the measured reflectance as a predicted value.

3. 2. The method for predicting the air content of a cement mix according to claim 1, further comprising the steps of: continuously measuring the reflectance at a plurality of time points; calculating statistical values ​​of the reflectance based on the plurality of reflectances measured at the plurality of time points; and predicting the air content based on the statistical values ​​of the reflectance.

4. The reflectance of the cement mixture is measured at multiple times using the reflectometer while being mixed by the mixer; The method for predicting the air content of a cement mix according to claim 3 , wherein the air content is predicted based on at least one reflectance that satisfies a convergence condition among the reflectances at the plurality of times.

5. The reflectance of the cement mixture is measured at multiple times using the reflectometer while being mixed by the mixer; 4. The method for predicting the air content of a cement kneaded body according to claim 3, wherein the air content is predicted using at least one reflectance measured from a first point in time to a second point in time that is a predetermined time before the second point in time at which the cement kneaded body is discharged by the mixer.

6. 6. The method for predicting the air content of a cement kneaded body according to claim 4 or 5, wherein the mixer has a light source that irradiates light onto the cement kneaded body in a kneading chamber, which is a dark place, and a reflectometer that measures the reflectance of the light irradiated onto the cement kneaded body by the light source.

7. a prediction unit that predicts the air content of the unhardened cement kneaded body based on the reflectance of light irradiated to the unhardened cement kneaded body measured by a reflectometer; a display unit that displays a prediction result by the prediction unit; A system for predicting the air content of a cement mix.

8. Obtaining the reflectance of light irradiated onto the unhardened cement mix measured by a reflectometer; Predicting the air content of the cement kneaded body based on the acquired reflectance; A program that causes one or more processors to execute the above.

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