Intelligent rapid tester for moisture content of concrete aggregate

Abstract

The invention relates to the field of measurement, in particular to an intelligent concrete aggregate moisture content rapid determinator, which comprises a signal transmitting and receiving module, which transmits electromagnetic waves at a series of set frequencies and collects reflection signals at each frequency; the signal processing module is used for carrying out signal processing on the collected reflected signals; and the dielectric constant calculation module is used for calculating the dielectric constant of the measured medium under each frequency according to the signal characteristic parameter and the relationship between the signal and the dielectric constant of the medium. The method has the advantages that the water content of the concrete aggregate can be continuously and rapidly measured, the damage degree to the concrete aggregate is small, a hardware circuit is simple, and the cost of corresponding measuring equipment is low. Compared with other various methods for measuring the water content of the concrete aggregate, the method has the advantages that portability is achieved, and the FDR has obvious advantages from the comprehensive characteristics of accuracy, continuity, equipment cost and the like.

Description

Technical Field

[0001] The invention relates to the field of measurement, in particular to an intelligent concrete aggregate moisture content rapid determination instrument. Background Art

[0002] The moisture content of concrete aggregate refers to the ratio of the water content in the aggregate to the absolute dry mass of the aggregate, which affects the water consumption, slump, strength and durability of concrete. There are many methods to determine the moisture content of aggregate. One commonly used method is the standard method, which is to weigh a certain mass of wet aggregate and put it into an oven to dry to constant weight, and then weigh the mass of the dried aggregate. Another method is the rapid detection method, which is to weigh a certain mass of fine aggregate into a container with a predetermined scale line, add water and stir to eliminate bubbles, add water to the scale line again, weigh its mass, then empty and wash the container, fill it with water to the scale line again, weigh its mass, and then calculate according to the formula. This method is faster and more convenient than the standard method, but it requires pre-making a container with scale lines and knowing the specific gravity of the fine aggregate.

[0003] FDR frequency domain reflectometry is a technique that uses the frequency of high-frequency electromagnetic waves propagating in a medium to measure the dielectric constant of a medium. It can be used to measure the volumetric moisture content of soil, because the dielectric constant of soil has a certain relationship with the moisture content. There are the following problems when using FDR frequency domain reflectometry to measure the moisture content of aggregates: 1. The shape, size, density, surface roughness and other factors of concrete aggregates will affect the propagation of electromagnetic waves in the medium, causing measurement errors; 2. The moisture content of concrete aggregates is unevenly distributed; 3. Environmental factors such as the temperature, salinity, and alkalinity of concrete aggregates will also affect the dielectric constant and the propagation of electromagnetic waves, which require correction or compensation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a rapid measuring instrument which can quickly measure the moisture content of concrete aggregate by using the FDR frequency domain reflection method and the measurement result is as close as possible to the standard method.

[0005] In order to achieve the above purpose, an intelligent concrete aggregate moisture content rapid measuring instrument is designed, which includes: a signal transmitting and receiving module, which transmits electromagnetic waves at a series of set frequencies and collects reflected signals at each frequency; a signal processing module, which performs signal processing on the collected reflected signals; a dielectric constant calculation module, which calculates the dielectric constant of the measured medium at each frequency according to the signal characteristic parameters and the relationship between the signal and the dielectric constant of the medium; the measuring instrument also includes a frequency selection button, which is used to select the concrete aggregate dielectric constant at an ideal frequency for decomposition; a sensor, which decomposes the imaginary part of the concrete aggregate moisture content through the sensor to obtain the concrete aggregate conductivity; the sensor decomposes the real part of the concrete aggregate moisture content through the sensor to obtain the concrete aggregate capacitance; the sensor measures the equivalent conductance and equivalent capacitance of the probe to calculate the moisture content of the concrete aggregate.

[0006] Compared with the prior art, the present invention has the following advantages:

[0007] It can continuously and quickly measure the moisture content of concrete aggregates, has little damage to concrete aggregates, has a simpler hardware circuit, and has a low cost for the corresponding measurement equipment. Compared with other methods for measuring the moisture content of concrete aggregates, it is portable. Considering the comprehensive characteristics of accuracy, continuity, equipment cost, etc., FDR has obvious advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the operating buttons of the moisture meter of the present invention; DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the accompanying drawings, and the structure and principle of the present invention are very clear to people in the field. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0010] The present invention adopts FDR (frequency domain reflectometry), and the specific steps are:

[0011] S1. Signal transmission and reception, transmitting electromagnetic waves at a series of set frequencies and collecting reflected signals at each frequency;

[0012] S2. Signal processing: performing signal processing on the collected reflection signal;

[0013] S3. Calculate the dielectric constant, and calculate the dielectric constant of the measured medium at each frequency according to the signal characteristic parameters and the relationship between the signal and the dielectric constant of the medium;

[0014] S4. Select the dielectric constant of concrete aggregate at the ideal frequency for decomposition;

[0015] S5. Obtaining the electrical conductivity of the concrete aggregate by decomposing the imaginary part of the water content of the concrete aggregate;

[0016] S6. By decomposing the real part of the water content of the concrete aggregate, the capacitance of the concrete aggregate is obtained;

[0017] S7. Calculate the moisture content of concrete aggregate by measuring the equivalent conductance and equivalent capacitance of the probe.

[0018] The sensor probe using the LC oscillation principle can convert the water content per unit volume of concrete aggregate into its own capacitance, which is fed back to the CPU for algorithm calculation to obtain the moisture content of the concrete aggregate.

[0019] Subsequent algorithm improvements can minimize the accuracy error compared to the drying method.

[0020] Main technical indicators:

[0021] Test range: 0~40%

[0022] Display mode: LED LCD

[0023] Frequency adjustment: 75~100MHz

[0024] Algorithm: FDR (Frequency Domain Reflectometry)

[0025] like Figure 1 As shown, the present invention uses a moisture meter to measure, and the specific steps are:

[0026] 1. Connect the sensor.

[0027] 2. Connect the power supply and press the power button to turn on the device.

[0028] 3. When the power display is lower than 30%, please charge it in time to avoid affecting the test accuracy.

[0029] 4. Test: Insert the sensor into the concrete aggregate, press the "test key" and wait for stabilization. The value shown on the display is the moisture content.

[0030] 5. Calibration:

[0031] a) Select the frequency selection button to the desired gear for testing. Turn it to the leftmost position for the highest frequency, and this position is recommended.

[0032] b) Press the “Function Key” to enter the function option interface, press the “Shift Key” to select the “Calibration” option and press the “Test Key” to enter.

[0033] c) The interface displays the number of calibration points. Press the "Add One" key to enter the desired number of calibration points. The maximum number of points is 9. After entering, press the "Test" key to confirm.

[0034] d) The interface displays the input standard value. At this time, divide the calibration sample into two parts, one of which is tested for standard moisture content by weighing method. Press the "add one" key to add one, press the "shift key" to shift, and enter the obtained standard moisture content into the interface. Then insert the sensor into the other sample. After the sampling value displayed on the interface is stable, press the "test" key to save and display the next point. After all points are entered in sequence, it will automatically save and exit. Restart the machine.

[0035] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes according to the technical solutions and novel concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An intelligent concrete aggregate moisture content rapid tester, the tester comprising: A signal transmitting and receiving module, which transmits electromagnetic waves at a series of set frequencies and collects reflected signals at each frequency; A signal processing module, wherein the signal processing module performs signal processing on the collected reflection signal; A dielectric constant calculation module, wherein the dielectric constant calculation module calculates the dielectric constant of the measured medium at each frequency according to the signal characteristic parameters and the relationship between the signal and the dielectric constant of the medium; It is characterized in that the measuring instrument also includes Frequency selection button, through which the concrete aggregate dielectric constant at the ideal frequency is selected for decomposition; The sensor decomposes the imaginary part of the water content of the concrete aggregate through the sensor to obtain the conductivity of the concrete aggregate; The sensor decomposes the real part of the moisture content of concrete aggregate to obtain the capacitance of concrete aggregate; the sensor measures the equivalent conductance and equivalent capacitance of the probe to calculate the moisture content of concrete aggregate.

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