JP3593377B2 - Method for measuring moisture content of fine aggregate for concrete and apparatus used for measuring moisture content - Google Patents

Description

[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a method for measuring the water content of fine aggregate for concrete, which enables the water content of fine aggregate for concrete to be quickly measured using microwaves, and to an apparatus used for measuring the water content.
[0002]
[Prior art]
In the production of ready-mixed concrete, it is desirable to adjust the water injection amount and the like according to the moisture content of the fine aggregate to produce a concrete of a constant quality. Therefore, it is necessary to measure the moisture content of the fine aggregate carried into a factory or the like. The inventors have announced a method for quickly measuring the water content in the collection of papers at the 48th Annual Meeting of the Japan Society of Civil Engineers, entitled "Trial Production of a Simple High-Frequency Phase-Type Moisture Meter". A brief description of the technology presented here is as follows. First, since the propagation speed of microwaves is delayed when passing through a substance having a large dielectric constant, the microwave is transmitted through a substance containing moisture having a constant dielectric constant, and the time delay is measured as a phase delay. This is based on the principle that moisture contained in a substance can be measured. Then, a fine aggregate sample having a constant moisture content was filled in a glass container, and microwaves were transmitted at different filling ratios to measure the phase lag between the fine aggregate sample and the container. We have found that the phase lag is large. Further, it was found that the filling rate increased when the fine aggregate sample was filled in a container and this was vibrated by a vibrator, but when the vibration was applied for about 3 minutes, the increase in the filling rate was almost saturated. Therefore, a fine aggregate sample having a known moisture content is filled in the container without pressurizing, and a vibration is applied to the container for about 3 minutes to transmit microwaves, and the phase lag is measured. This measurement was performed using various known water contents from a completely dry state (a state in which a fine aggregate sample was dried in a drying oven at 100 to 110 ° C. for 24 hours) to a wet state (a state having a higher moisture content than a surface dry saturated state). As a result, a graph of the characteristic of the unique moisture content and the characteristic of the phase lag was obtained. As a result, if the graph is measured in advance for a fine aggregate, the phase lag is measured for a fine aggregate sample newly brought into a factory or the like, and this phase lag is immediately hydrated by illuminating the graph. The rate can be measured.
[0003]
[Problems to be solved by the invention]
The technique disclosed in the above-mentioned collection of papers is extremely excellent because the moisture content of a fine aggregate sample can be quickly measured. However, the above measurement merely measures the water content of the sampled fine aggregate brought into a factory or the like. It is desirable to be able to measure the moisture content for the entire amount of fine aggregate. Furthermore, it is desirable to be able to incorporate it between the storage bin and the weighing bin in the factory.
[0004]
The present invention provides a method for measuring the moisture content of fine aggregate for concrete, which can measure the moisture content from the fine aggregate in a flowing state, and an apparatus used for the measurement of the moisture content, in order to satisfy the needs as described above. Aim.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the method for measuring the moisture content of fine aggregate for concrete according to the present invention is directed to transmitting microwaves from a lateral direction to a cylindrical empty falling container made of a dielectric material and arranged in a vertical direction. Then, the measured value of the phase meter is adjusted to zero by correcting the phase delay due to the propagation path of the microwave including the empty falling container, the fine aggregate sample is allowed to flow down into the falling container, and the phase meter is used. While measuring, this changing measured value is recorded in the recording means with time, the average value of the changing measured value is calculated, and this is set as a phase lag by the fine aggregate sample, and the flow of the fine aggregate sample flowing down is calculated. The mass is measured by the weight measuring means, and the flow rate of the fine aggregate sample is calculated from the mass and the time required for the flow down, and the fine aggregate sample which has been previously dried and the absolute aggregate sample passes through the flow-down container. Calculate the correction value from the flow rate that can flow down, Calculate the corrected phase lag from the correction value and the phase lag due to the fine aggregate sample, and using the fine aggregate sample having a known moisture content, the moisture content previously created through the above-described process versus the corrected phase lag. The moisture content is obtained by illuminating the characteristic data with the corrected phase delay.
[0006]
Further, a microwave is transmitted from a lateral direction to a cylindrical falling container made of a dielectric material and disposed in the longitudinal direction, and a phase delay due to the propagation path of the microwave is measured by a phase meter. The fine aggregate sample is allowed to flow down, and the phase lag due to the propagation path is measured by the phase meter, and the changed measurement value is recorded in a recording unit with time, and the average value of the changed measurement value is calculated. The phase delay of the fine aggregate sample is calculated by subtracting the phase delay of the propagation path including the empty falling container from the value, the mass of the flowed fine aggregate sample is measured by weight measuring means, and this mass and The flow rate of the fine aggregate sample is calculated from the time required for the flow, and a correction value is calculated from the flow rate and the flow rate at which the fine aggregate sample that has been previously dried is allowed to flow down the flow container, This correction value and the calculated value A phase delay corrected from the phase delay due to the aggregate sample is calculated, and the corrected phase delay characteristic data is corrected using the fine aggregate sample having a known moisture content through the above-described process. The moisture content may be determined by illuminating the determined phase delay.
[0007]
The apparatus used for measuring the water content of the fine aggregate for concrete according to the present invention is a cylindrical falling container made of a dielectric material and arranged in the vertical direction, and is provided above the falling container and can be opened and closed by a shutter. A sample introduction means for causing the fine aggregate sample to flow down into the flow-down container, a sample receiving means provided below the flow-down container to receive the fine aggregate sample flowing down, and the sample receiving means received by the sample receiving means. Weight measuring means for measuring the mass of the fine aggregate sample, a waveguide in which the falling container is interposed, a microwave oscillator for injecting microwaves into one end of the waveguide, and other components in the waveguide A probe for picking up the microwave propagated at the end, and the microwave incident on one end of the waveguide in a state where the fine aggregate sample is flowing downward from above in the flowing container. Transfer to the other end of the waveguide The phase delay of the microwave picked up is measured, and the phase delay of the microwave propagated from one end of the waveguide to the other end in an empty state of the falling vessel is subtracted from the measured phase delay. And a phase meter that outputs only the phase lag due to the fine aggregate sample, and the fine aggregate sample that has been output from the phase meter to the sample receiving means flows into the sample receiving means. Recording means for recording the time required for the recording.
[0008]
A cylindrical flow-down container made of a dielectric material and disposed in the longitudinal direction, and a sample input means provided above the flow-down container and capable of opening and closing a fine aggregate sample into the flow-down container by a shutter and capable of being opened and closed. Sample receiving means provided below the flow-down container for receiving the fine aggregate sample flowing down; weight measuring means for measuring the mass of the fine aggregate sample received by the sample receiving means; A waveguide in which a container is interposed, a microwave oscillator for injecting a microwave at one end of the waveguide, a probe for picking up the microwave propagated at the other end of the waveguide, Microwave incident on one end of the waveguide in a state where the fine aggregate sample is flowing down from above to below in the container and in an empty state of the falling container propagates to the other end of the waveguide. Picked up A phase meter that measures the phase delay of each microwave and outputs the phase aggregate as it is, and the fine aggregate sample that is in the sample input unit and has a measured value in a state where the fine aggregate sample flows down that is output from the phase meter. Recording means for recording the time required to flow down to the sample receiving means.
[0009]
[Operation]
In the method for measuring the water content of fine aggregate for concrete according to claims 1 and 2, the flow rate of the fine aggregate sample flowing down the falling container from above to below changes due to the change in the water content, and the fine aggregate sample Does not uniquely correspond to the water content. However, since the phase lag is proportional to the flow rate, if the measured phase lag is corrected to a state in which the falling container is allowed to flow down by the mass that can flow in the dry state at the water content, the corrected phase lag is unambiguous with the water content. Correspondingly. Therefore, using a fine aggregate sample with a known moisture content, a graph of the water content versus the phase lag characteristic corrected in advance was created, and the phase lag was measured from the fine aggregate sample with an unknown moisture content to correct this. The moisture content can be measured by illuminating the corrected phase lag with a previously created graph.
[0010]
In the apparatus used for measuring the moisture content of fine aggregate for concrete according to claims 3 and 4, since the moisture content can be measured from the fine aggregate sample flowing downward from above, the storage bin and the weighing bin can be measured. Can be easily incorporated during.
[0011]
【Example】
An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram of an embodiment of an apparatus used for measuring the water content of fine aggregate for concrete according to the present invention. FIG. 2 is a flowchart for explaining the operation for obtaining the water content of the embodiment of the method for measuring the water content of fine aggregate for concrete using the apparatus shown in FIG. 1, and FIG. It is a flowchart which produces | generates the graph of the obtained phase delay characteristic, and (b) is a flowchart which calculates | requires the unknown moisture content of a fine aggregate sample. FIG. 3 is a graph of a water content versus a phase lag characteristic of a flowing fine aggregate sample. FIG. 4 is a graph of the water content versus the corrected phase lag characteristic for a flowing fine aggregate sample.
[0012]
First, the configuration of the apparatus used for measuring the water content of the fine aggregate for concrete of the present invention will be described. As shown in FIG. 1, a tubular falling container 12 is provided at the center of a horizontally arranged waveguide 10 and is arranged in the longitudinal direction. The falling container 12 has upper and lower ends opened, and is made of a dielectric material such as glass. A microwave oscillator 16 is connected to one end of the waveguide 10 via an isolator 14. A probe 18 is provided at the other end of the waveguide 10. A part of the microwave (for example, 2.45 GHz) oscillated by the microwave oscillator 16 propagates through the waveguide 10 via the isolator 14 and further passes through the falling vessel 12 and is picked up by the probe 18. It is provided to the phase meter 20. The phase meter 20 includes a phase delay detector 20a for detecting a phase delay of the microwave provided from the isolator 14 and the probe 18, a memory 20b for recording the measured phase delay, and a memory 20b for storing the measured phase delay. And a calculator 20c for calculating a difference between phase delays recorded in advance. The measured values output from the calculator 20c are recorded with time by the XT recorder 22 as recording means. Further, above the falling container 12, there is provided a sample loading container 28 as a sample loading means for allowing the fine aggregate sample 26 to flow down into the falling container 12 so as to be freely opened and closed by the shutter 24. Further, a sample receiving container 30 as a sample receiving means for receiving the flowing fine aggregate sample 26 is provided below the falling container 12. The sample receiving container 30 is configured to be able to measure the mass of the fine aggregate sample 26 stored by the weight measuring device 32 as the weight measuring means.
[0013]
Next, a method for measuring the water content of the fine aggregate sample 26 using the apparatus shown in FIG. 1 will be described. First, the phase delay of the microwave at both ends of the microwave propagation path of the waveguide 10 including the empty falling vessel 12 is measured by the phase delay detector 20a, and the measured value is stored in the memory 20b (FIG. 2). (A) Step 1). Next, in a state where the fine aggregate sample 26 having a known moisture content is allowed to flow downward from above into the falling container 12 from the sample input device 28 with the shutter 24 opened, the phase lag at both ends of the waveguide 10 is performed. Is measured by the phase delay detector 20a, and the phase delay of the propagation path including the empty falling vessel 12 stored in the memory 20b is subtracted from the phase delay measured by the calculator 20c, and the calculated value is used as a measured value as an XT recorder. 22 and is recorded over time. Moreover, since the mass per unit time of the flowing fine aggregate sample 26 changes, the average value of the phase lag recorded in the XT recorder 22 is appropriately calculated, and this is used to calculate the phase lag of the fine aggregate sample 26 at the water content. This is delayed (step 2 in FIG. 2A). Here, in the output of the arithmetic unit 20c, the phase delay caused by the empty falling container 12 and the like has already been corrected, and the phase delay caused only by the flowing fine aggregate sample 26 is output as a measured value. Then, the mass of the fine aggregate sample 26 flowing down and stored in the sample receiving container 30 is measured by the weight measuring device 32 (step 3 in FIG. 2A). Further, the time required for the fine aggregate sample 26 having this mass to flow down is obtained from the record of the XT recorder 22, and the flow rate of the fine aggregate sample 26 at the water content is appropriately calculated (FIG. 2 (a) step). Four). Further, the flow rate when the same fine aggregate sample 26 in the completely dried state is caused to flow down the falling container 12 is measured in advance, and the flow rate obtained in step 4 of FIG. Is obtained as a flow rate correction value (step 5 in FIG. 2A). The phase delay obtained in step 2 of FIG. 2A is corrected using the flow rate correction value α, and the corrected phase delay is calculated (step 6 of FIG. 2A). Then, the known water content is variously changed in the range of the wet state, and the phase lag corrected by each fine aggregate sample 26 is measured until a predetermined number of measured values enough to write a graph showing the characteristics are obtained. Repeat (Step 7 in FIG. 2A). Once a predetermined number of measured values have been obtained, a graph of the moisture content versus the corrected phase lag characteristic is created from these data, as shown in FIG. 4 (step 8 in FIG. 2 (a)). The known moisture content may be obtained, for example, by setting the fine aggregate sample 26 in a completely dry state and injecting water into the fine aggregate sample 26 at a predetermined rate.
[0014]
By the way, the characteristic of the water content versus the phase lag measured in step 2 of FIG. 2A is a graph as shown in FIG. 3, and the water content is not uniquely determined with respect to the phase lag. In the wet state, the surface water increases as the water content increases, and the adhesion between the particles of the fine aggregate sample 26 increases. As a result, the higher the water content, the more difficult it is for the fine aggregate sample 26 to flow down in the flow-down container 12, and the lower the flow rate from the top to the bottom is reduced. Therefore, the phase lag is converted in steps 3 to 6 in FIG. 2A by assuming that the flow rate of the water content in the flow-down vessel 12 is such that it can flow down in a completely dry state. By this conversion, the difference in the flow rate due to the difference in the water content can be corrected, the characteristics of the water content and the corrected phase lag at the same flow rate are obtained, and the characteristics as shown in FIG. 4 are obtained. In the characteristic shown in FIG. 4, the moisture content is uniquely determined with respect to the corrected phase delay.
[0015]
Next, the operation of measuring the water content of the fine aggregate sample 26 whose water content is unknown using the graph of the water content versus the corrected phase lag characteristic thus created will be described. First, the phase delay at both ends of the propagation path including the empty falling vessel 12 is measured (step 1 in FIG. 2B), and data for correcting the measurement value output from the calculator 20c of the phase meter 20 is obtained. Get. Then, the fine aggregate sample 26 having an unknown water content is allowed to flow down from the sample input container 28 to the falling container 12, and the phase delay caused by the fine aggregate sample 26 is recorded with the XT recorder 22 with time, and the average of the changing phase delay is recorded. The value is calculated (step 2 in FIG. 2B). Then, for the fine aggregate sample 26 having an unknown water content, the measured phase delay is calculated to the corrected phase delay in the same manner as in steps 3 to 6 in FIG. 2A (FIG. 2B). Steps 3-6). Then, the phase lag obtained and corrected in step 6 of FIG. 2B is compared with the water content of the fine aggregate sample 26 prepared in advance by the process of FIG. The water content is determined by referring to the graph (step 7 in FIG. 2B).
[0016]
In this manner, by previously creating a graph of the moisture content versus the corrected phase lag characteristic as shown in FIG. 4 for each fine aggregate sample 26, the fine aggregate having an unknown moisture content that is carried into a factory or the like is prepared. The water content of the sample 26 can be quickly measured in a flowing state.
[0017]
By the way, in order to incorporate the device for measuring the moisture content of fine aggregate for concrete of the present invention as described above between a storage bin in a factory or the like and a weighing bin, the storage bin acts as a sample input container 28, It can be easily understood that the bottle may be made to function as the sample receiving container 30 and the weighing device 32.
[0018]
In the description of the above embodiment, the phase meter 20 corrects the phase lag due to the propagation path including the empty flow-down container 12, and the fine aggregate sample flowing down the flow-down container 12 from above to below from the phase meter 20. 26 is output as a measured value, but the present invention is not limited to this. The phase delay at both ends of the waveguide 10 is directly recorded in the XT recorder 22, and the average value calculated from the recorded measured value is used. Therefore, the phase delay of the propagation path including the empty falling container 12 measured separately may be subtracted. In this case, the phase delay of the propagation path including the empty flow-down vessel 12 may be made before or after the fine aggregate sample 26 flows down. Further, the phase delay measured by the phase meter 20 is recorded with time, so long as the average value of the phase delay due to the flow of the fine aggregate sample 26 and the time required for the flow can be measured, and the recording is not limited to the recording to the XT recorder 22. Instead, the measurement value output from the phase meter 20 may be sampled and recorded in a computer or the like. Furthermore, in the above-described embodiment, a description has been given of creating a graph of the water content versus the phase lag characteristic corrected in advance. However, the present invention is not limited to this, and data capable of creating a graph is stored in a computer or the like, and the unknown moisture content is stored. The moisture content may be appropriately calculated by a computer or the like from the phase delay measured from the fine aggregate sample 26 and the mass thereof.
[0019]
【The invention's effect】
The method for measuring the water content of fine aggregate for concrete and the apparatus used for measuring the water content of the present invention have the following special effects.
[0020]
In the method for measuring the moisture content of fine aggregate for concrete according to claims 1 and 2, the unknown moisture content can be measured in a state where the fine aggregate sample flows downward from above, and the fine aggregate can be measured. The moisture content can be measured for the entire amount of the sample.
[0021]
In the apparatus for measuring the moisture content of fine aggregate for concrete according to claims 3 and 4, the unknown moisture content can be measured in a state where the fine aggregate sample flows down from above to below. It can be incorporated during the concrete manufacturing process.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of an apparatus used for measuring the water content of fine aggregate for concrete according to the present invention.
FIG. 2 is a flowchart for explaining the operation of obtaining the water content of the embodiment of the method for measuring the water content of fine aggregate for concrete using the apparatus shown in FIG. 1; It is a flowchart which produces | generates the graph of the obtained phase delay characteristic, and (b) is a flowchart which calculates | requires the unknown moisture content of a fine aggregate sample.
FIG. 3 is a graph of a water content versus a phase lag characteristic of a fine aggregate sample flowing down.
FIG. 4 is a graph of moisture content versus corrected phase lag characteristics for a flowing fine aggregate sample.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 waveguide 12 falling container 14 isolator 16 microwave oscillator 18 probe 20 phase meter 20 a phase delay detector 20 b memory 20 c arithmetic unit 22 XT recorder 24 shutter 26 fine aggregate sample 28 sample input container 30 sample receiving container 32 weighing device

Claims (4)

The microwave is transmitted from the lateral direction to a cylindrical empty falling container made of a dielectric material and arranged in the vertical direction, and the phase is corrected by correcting the phase delay due to the propagation path of the microwave including the empty falling container. The measured value of the meter is adjusted to zero, the fine aggregate sample is caused to flow down into the falling container, and measured by the phase meter.The changing measured value is recorded in the recording means with time, and the changing measured value is measured. Calculate the average value and use this as the phase lag by the fine aggregate sample, measure the mass of the flowed fine aggregate sample by weight measuring means, and calculate the fine aggregate from the mass and the time required for the flow. A flow rate of the sample is calculated, and a correction value is calculated from the flow rate and a flow rate at which the fine aggregate sample previously dried to flow down the falling container, and the correction value and the phase by the fine aggregate sample are calculated. Calculate the corrected phase delay from the delay and Using a fine aggregate sample having a water content, and calculating the water content by illuminating the corrected phase lag characteristic data with the corrected phase lag characteristic data prepared in advance through the above process. Method for measuring moisture content of aggregate. Microwaves are transmitted from the lateral direction to a cylindrical flow-down container made of a dielectric material and arranged in the vertical direction, and the phase delay due to the microwave propagation path is measured by a phase meter, and the fine bone is placed in the flow-down container. A material sample is caused to flow down, and the phase lag due to the propagation path is measured by the phase meter, and the changed measurement value is recorded in a recording unit with time, and the average value of the changed measurement value is calculated. The phase delay of the fine aggregate sample is calculated by subtracting the phase delay of the propagation path including the empty falling container, the mass of the flowed fine aggregate sample is measured by weight measuring means, and this mass and the flow Calculate the flow rate of the fine aggregate sample from the time required, and calculate a correction value from this flow rate and the flow rate at which the fine aggregate sample that has been previously dried out can flow down the falling container. Value and the calculated fine aggregate The phase lag is calculated from the phase lag due to the material and the phase lag is corrected to the corrected phase lag characteristic data with respect to the moisture content previously created through the above-described process using a fine aggregate sample having a known moisture content. A method for measuring the water content of fine aggregate for concrete, characterized in that the water content is determined in light of phase lag. A cylindrical flow-down container made of a dielectric material and disposed in the longitudinal direction, and a sample input means provided above the flow-down container and capable of opening and closing a fine aggregate sample into the flow-down container by a shutter and capable of being opened and closed, and A sample receiving means provided below the falling container for receiving the fine aggregate sample flowing down; a weight measuring means for measuring the mass of the fine aggregate sample received by the sample receiving means; A waveguide to be mounted, a microwave oscillator for injecting a microwave into one end of the waveguide, a probe for picking up the microwave propagated at the other end of the waveguide, and a In the state where the fine aggregate sample is flowing downward from above, the phase lag of the microwave propagating to the other end of the waveguide and being picked up with respect to the microwave incident at one end of the waveguide is described. Measure and From the measured phase lag, the phase lag of the microwave propagated from one end of the waveguide to the other end is corrected by subtracting the phase lag of the microwave from the one end of the waveguide in an empty state, and only the phase lag by the fine aggregate sample is corrected. A phase meter for outputting, and recording means for recording the measured value output from the phase meter together with the time required for the fine aggregate sample in the sample input means to flow down to the sample receiving means. An apparatus for measuring the water content of fine aggregate for concrete, characterized by comprising. A cylindrical flow-down container made of a dielectric material and disposed in the longitudinal direction, and a sample input means provided above the flow-down container and capable of opening and closing a fine aggregate sample into the flow-down container by a shutter and capable of being opened and closed, and A sample receiving means provided below the falling container for receiving the fine aggregate sample flowing down; a weight measuring means for measuring the mass of the fine aggregate sample received by the sample receiving means; A waveguide to be mounted, a microwave oscillator for injecting a microwave into one end of the waveguide, a probe for picking up the microwave propagated at the other end of the waveguide, and a Microwaves incident on one end of the waveguide are propagated to the other end of the waveguide in a state where the fine aggregate sample is flowing downward from above and in an empty state of the falling container, and are picked up. Microwave A phase meter for measuring the phase lag and outputting the phase aggregate as it is, and the fine aggregate sample output from the phase meter in a state where the fine aggregate sample flows down is in the sample receiving means. Recording means for recording the time required to flow down to the means, and an apparatus used for measuring the moisture content of fine aggregate for concrete.

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