JP2000304707A - Unit water quantity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a unit water quantity measuring apparatus capable of simply measuring the unit water quantity of fresh concrete before casting on the spot in a short time with high accuracy. SOLUTION: A coil support pipe 12 is provided inside a cylindrical body 11 and a coil 13 is wound around the outer periphery of the coil support pipe 12 and first and second electrodes 14, 15 are arranged in opposed relationship so as to hold the coil therebetween and the coil 13 and the respective electrodes 14, 15 are hermetically closed from the outside by wall bodies 16a, 16b in such a state that both end opening parts of the coil support part 12 are allowed to face to the outside through mesh members 17a, 17b to constitute a measuring part 1. Only a mortar component is allowed to flow in the coil support pipe 12 only by inserting the measuring part 1 in fresh concrete and, in this state, a microwave is applied to the first electrode 14 while frequency is swept and resonance frequency is detected through the second electrode 15 to obtain the data related to the quantity of moisture contained in the mortar component within the coil support pipe 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a unit water amount of fresh concrete, and more particularly, to a unit water amount measuring apparatus capable of quickly measuring a unit water amount at a concrete placing site or the like.

[0002]

2. Description of the Related Art In general, concrete achieves its intended performance only when a designed mix is properly performed. In particular, the unit water amount, which is the weight of water per unit volume of fresh concrete, is shrunk. It is a major factor in determining the quality of concrete, such as a large contribution to the occurrence of cracks.In addition to the mixing water, there is too much surface water of the aggregate compared to other components that make up concrete. This is a difficult factor in terms of management, such as a large change in the value.

[0003] In view of the above, in order to guarantee the quality of concrete, conventionally, the unit water amount of fresh concrete before casting is measured. In measuring the unit water volume, the mortar is sampled by sifting only the mortar component from the fresh concrete to be measured, and the sampled mortar is
Generally, a method of heating and drying using a gas stove, an electric heater, or an infrared dryer or a microwave oven, measuring the weight before and after the drying, and calculating the unit water amount from the weight difference and the mortar weight before the drying is generally used. Has been adopted.

[0004]

However, the conventional method of measuring the unit water amount as described above requires not only the operation of sieving mortar components from fresh concrete but also sampling the mortar, and drying the sampled mortar. In order to accurately measure the unit water amount, it is necessary to continue heating to dry the mortar completely or close to the mortar, so that the measurement takes a long time.

[0005] The present invention has been made in view of such circumstances, and provides a unit water amount measuring apparatus capable of easily and accurately measuring the unit water amount of concrete before casting on site. It is an object.

[0006]

In order to achieve the above-mentioned object, a unit water amount measuring device of the present invention is a unit water amount measuring device for measuring a unit water amount of fresh concrete based on a microwave resonance method. , A coil support tube inserted coaxially into the cylinder, a coil wound around the coil support tube, and first and second coils disposed opposite to each other with the coil interposed therebetween. In addition to the electrodes, both ends of the cylindrical body are sealed from the outside with the both ends of the coil support tube facing the outside and the coil and the first and second electrodes are housed inside. And a mesh member attached to both ends of the coil support tube, and a measuring unit capable of immersing the whole in fresh concrete, and a frequency sweeping device for the first electrode. A microwave oscillator for applying a microwave while applying the microwave; and a detection circuit connected to the second electrode for detecting a resonance frequency of the measuring unit. (Claim 1).

Further, in the present invention, in addition to the above configuration, a storage means for storing calibration curve information prepared in advance, and using the stored contents, a result of the detection of the resonance frequency by the detection circuit can be used for fresh concrete. (Claim 2) can be adopted.

The present invention is to apply the measurement principle of a microwave resonance type moisture meter to the on-site measurement of a unit amount of fresh concrete and to immerse the entire measuring unit in the fresh concrete. Thus, the mortar sampling operation is not required, and the unit water amount of the fresh concrete is accurately measured simply and quickly.

The microwave resonance type moisture meter measures the amount of water in a sample by utilizing the fact that water has an extremely large dielectric constant as compared with other substances. Is incorporated in a resonator system, and a change in resonance frequency caused by a change in the capacitance C of the resonator according to the amount of water contained in the sample is captured, and the amount of water contained in the sample is measured.

In the present invention, a helical line resonator is employed as the resonator, and both ends of a coil support tube for supporting a coil of the resonator are exposed from both ends of a cylindrical body constituting an outer shell of the resonator. In addition, both ends of the cylinder are sealed to the outside by the wall while the coil and the two electrodes are housed inside, and the structure of the measuring unit is adopted in which mesh members are provided at both ends of the coil support tube. are doing. Due to the structure of this measuring part, only the whole measuring part is immersed in the fresh concrete, only the mortar component in the fresh concrete is introduced into the coil support tube through the mesh member and incorporated into the resonator system. State. In this state, the microwave is applied to the first electrode while sweeping the frequency, and the resonance frequency is detected through the second electrode, whereby the amount of water in the mortar introduced into the coil support tube is obtained. , The sampling operation of the mortar component from the fresh concrete is not required, and the information on the unit water amount can be obtained accurately in a shorter time than the measurement based on the conventional drying method.

Further, as in the invention according to claim 2, data of a calibration curve representing the relationship between the detection result of the resonance frequency by the detection circuit and the unit water amount is created and stored in advance, and as described above. When the detected resonance frequency is converted into a unit water amount, the unit water amount of the concrete can be measured immediately by merely immersing the measuring unit in the fresh concrete.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of an embodiment of the present invention, and FIG. 2 is an overall configuration diagram showing both a schematic vertical sectional view showing the structure of a measuring section 1 and a block diagram showing an electrical configuration. is there.

The measuring unit 1 comprises a cylindrical conductor 11, a coil support tube 12 arranged coaxially with the cylindrical conductor 11, and a coil support tube 1
１ ／ wavelength single-layer solenoid coil 13, a first electrode 14 and a second electrode 15 disposed on both sides of the coil 13 with the coil 13 interposed therebetween, and a cylindrical conductor 11. A wall body 16 whose both ends are closed with the coil 13 and the first and second electrodes 14 and 15 housed, with both ends of the coil support tube 12 facing the outside.
a and 16b. Mesh members 17a and 17b are mounted on both ends of the coil support tube 12, respectively. The openings of the mesh members 17a and 17b prevent coarse aggregate in fresh concrete from passing therethrough. The thickness is such that only the mortar component can pass, for example, about 2.5 mm.

The measuring section 1 is fixed to one end of a support rod 18, a grip 18a is formed at the other end of the support rod 18, and the following section is provided at an intermediate portion of the support rod 18. The control box 3 accommodating the electric circuit is mounted.

In the control box 3, a ramp generator 21 for generating a ramp-shaped voltage signal and an output of the ramp generator 21 are inputted as a control voltage signal, for example, about 0.5 to 1.0 GHz. A voltage-controlled oscillator 22 oscillating in the microwave band, a frequency counter 23 for measuring the oscillation frequency of the voltage-controlled oscillator 22, and a second electrode 1
5, a detector 24 for supplying the output to the ramp generator 21, an operation control unit 25 for controlling the entire apparatus and performing an operation described later, and a calibration curve used for the operation. A memory 26 for storing data and a power supply circuit 27 for supplying necessary power to these circuits are accommodated. On one surface of the control box 3, an operation switch 31 for giving a measurement command and a unit A display 32 for displaying the measurement result of the water amount is attached.

The arithmetic and control unit 25 operates the operation switch 31 to give a measurement command to the ramp wave generator 21.
And outputs a start command to the first electrode 1
4 is applied from the voltage-controlled oscillator 22 a microwave whose frequency changes with time according to the instantaneous voltage value of the ramp wave. The detector 24 is connected to the resonator 1 via the second electrode 15.
The output of the ramp generator 21 is held for a certain period of time t by its output,
The frequency in the hold state, that is, the resonance state is counted by the frequency counter 23. That is, FIG.
(A) is an example of the voltage waveform of the ramp wave output from the ramp generator 21. If the resonator 10 resonates at the frequency f, the resonance phenomenon is captured by the detector 24 and the The output signal from 21 is held at a constant voltage value for a fixed time t as shown in FIG. 2B, and its resonance frequency f is measured by the frequency counter 23 and taken into the arithmetic control unit 25.

According to the above embodiment of the present invention, the measuring unit 1 is simply immersed in fresh concrete,
The unit water amount of the concrete can be immediately displayed on the display 32.

That is, when the measuring section 1 is immersed in the fresh concrete, only the mortar component enters the coil supporting tube 12 through the mesh sections 17a and 17b. In this state, the capacitance of the resonator 10 is greatly changed by water contained in the mortar in the coil support tube 12, and the resonance frequency is changed. When the operation switch 31 is operated in this state to give a measurement command, the resonator 10 resonates at the resonance frequency in that state, and the resonance frequency is taken into the arithmetic and control unit 25. This resonance frequency is correlated with the amount of water in the mortar that has penetrated into the coil support tube 12, and the internal volume of the coil support tube 12 is constant. Information relating to the amount of water in the sample will be captured. Calibration curve data as shown in FIG. 4 showing the relationship between the unit water amount and the resonance frequency of the resonator 10 is obtained in advance using another method such as a drying method and stored in the memory 26. From the contents stored in the memory 26 and the detection result of the resonance frequency of the resonator 10, the unit water amount of fresh concrete can be immediately calculated and displayed on the display 32.

In the above embodiment, the resonator 10
The result of detection of the resonance frequency is converted into a unit water amount by the arithmetic and control unit 25 in the control box 3 and is displayed on the display 32 provided in the control box 3 as well. However, the present invention is not limited to this. It is a matter of course that a configuration may be adopted in which the detection result of the resonance frequency of the vessel 10 is wirelessly transmitted to a separately provided arithmetic unit, and the arithmetic unit calculates the unit water volume.

Further, it goes without saying that other known circuits can be used as the means for detecting the resonance frequency of the resonator 10 in addition to the circuit used in the above embodiment.

[0021]

As described above, according to the present invention, a microwave resonance system using a helical line resonator as a resonator is adopted as a measurement system, and the two ends of the coil support tube of the resonator are respectively provided at the openings. The measuring unit is mounted with a mesh member and exposed to the outside, and the coil and the first and second electrodes are housed between the cylindrical body of the resonator outer shell and the coil support tube, and are hermetically sealed from the outside. By simply immersing the measuring unit in fresh concrete, only the mortar component in the concrete is introduced into the coil support tube, and immediately obtains accurate information on the amount of water in the mortar. Simplifies the measurement work and achieves a shorter and more accurate measurement work compared to the conventional unit water volume measurement method in which conventional mortar components are sieved and heated and dried. Door can be.

[Brief description of the drawings]

FIG. 1 is an external view of an embodiment of the present invention.

FIG. 2 is an overall configuration diagram showing both a schematic longitudinal sectional view showing the structure of a measuring section 1 according to the embodiment of the present invention and a block diagram showing an electrical configuration.

FIG. 3 is a time chart showing an example of an output waveform of the ramp generator 21 according to the embodiment of the present invention, wherein (A) shows the resonator 1;
0 shows an output waveform in a state where no resonance occurs, and FIG.
FIG. 7 is a diagram illustrating output waveforms when 0 resonates at a frequency f.

FIG. 4 is a graph showing an example of calibration curve data stored in advance in a memory 26 according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measuring part 11 Cylindrical conductor 12 Coil support tube 13 Single layer solenoid coil 14 1st electrode 15 2nd electrode 16a, 16b Wall 17a, 17b Mesh member 18 Support rod 18a Grip 21 Ramp generator 22 Voltage control oscillator 23 Frequency counter 24 Detector 25 Operation control unit 26 Memory 3 Control box 31 Operation switch 32 Display

Claims (2)

[Claims] 1. A unit water amount measuring device for measuring a unit water amount of fresh concrete based on a microwave resonance method, comprising: a cylindrical body made of a conductor; a coil support tube inserted coaxially into the cylindrical body; A coil wound around the coil support tube, and first and second electrodes opposed to each other with the coil interposed therebetween, and both ends of the cylindrical body are connected to both ends of the coil support tube. To the outside, and
A wall body for sealing the coil and the first and second electrodes from the outside with the coil and the first and second electrodes housed therein; and mesh members attached to both end openings of the coil support tube, and the entirety thereof is fresh. A measuring unit that can be immersed in concrete; a microwave oscillator that applies a microwave while sweeping a frequency to the first electrode; and a resonance frequency of the measuring unit that is connected to the second electrode and detected A unit for measuring the amount of unit water, characterized in that the mesh member has an opening for introducing only mortar in fresh concrete into the inside of the coil support tube. 2. A storage means for storing calibration curve information created in advance, and an arithmetic means for converting a detection result of the resonance frequency by the detection circuit into a unit water amount of fresh concrete using the stored contents. The unit water amount measuring device according to claim 1, wherein: