JPH0890549A - Kneading apparatus of ready-mixed concrete - Google Patents

Abstract

PURPOSE: To accurately supply water corresponding to a compounding ratio by accurately measuring the moisture values of aggregate in all of states. CONSTITUTION: A kneading system of ready-imixed concrete is equipped with the weighing hoppers 12, 13 provided to the lower parts of aggregate storage bins 1, 2, 3 through natural falling passages 20, the mixer 16 kneading cement C, water W and the aggregate Z supplied from the weighing hoppers, high accurate moisture meter sensors 9, 10, 11 provided so as to cross the falling passages and capable of measuring aggregate in all of states, that is, an absolute dry state, an air-dried state, a surface-dried state and a wet state and a control unit 30 to which the respective measured data of the weighing hoppers and the high accuracy moisture meter sensors are inputted. The control unit 30 calculates the wt. of the aggregate and the amt. of water on the basis of the measured data from the high accurate moisture meter sensors and corrects the preset wt. of the aggregate and the preset supply amt. of water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green concrete kneading system.

[0002]

2. Description of the Related Art In ready-mixed concrete, the mixing ratio of cement, water, aggregate and the like is adjusted depending on workability at the time of placing concrete and strength of concrete required by a structure. The strength and workability of concrete are governed by the slump value. This slump value is determined by the mixing ratio of cement, water, aggregate, etc., but the amount of water is particularly large, and the amount of water in concrete is expressed as the magnitude of the slump value.

In concrete materials, the amount of water content of aggregates is apt to change, and even if the amount of other materials is mixed and the materials are accurately controlled, the water content of aggregates, especially fine aggregates such as sand, etc. The slump value fluctuates due to the fluctuation of.

Therefore, conventionally, the moisture content of the aggregate is measured by a moisture meter, and the amount of water to be supplied is corrected based on the measured value.

[0005]

In the conventional example, as a moisture meter, (1) a dielectric moisture meter that irradiates electromagnetic waves to detect the dielectric constant and converts the moisture content into a moisture content for measurement, and (2) irradiates weak radiation Radioisotope moisture meter for measuring hydrogen concentration, (3)
An infrared moisture meter is used that projects light having a comparison wavelength in the near-infrared region and measures the reflected energy.

However, it is difficult to accurately measure the moisture value of the aggregate with the moisture meters of the above (1) to (3). or,
Since the set weight of aggregate in the mixing ratio also does not consider the moisture value in all the states of the aggregate, it is not possible to make an accurate mixing ratio, and the moisture that can accurately measure the moisture value in all the above states. There was no plan.

Here, all the states of the aggregate refer to the following four states. (1) Absolutely dry state: 100 to 1 aggregate as shown in FIG. 6A
It means a state of being dried by heating to a constant weight in a dryer at 10 ° C, and a state in which all the water contained in the voids in the aggregate particles K has been removed. That is, the water content is zero.

(2) Air-dried state: As shown in FIG. 6B, the aggregate is left in the air to be dried, and the aggregate grains K have some water W therein.

(3) Surface dry state: As shown in FIG. 6C, this is a state in which the surface water of the aggregate grains K is not present and the voids inside the aggregate grains K are filled with water W.

(4) Wet state: As shown in FIG. 6D, the inside of the aggregate grains K is saturated with water W and the surface water SW is present.

In the conventional example, since the amount of water could not be accurately supplied in accordance with the mixing ratio, the operator visually inspected the kneading condition of the green concrete during kneading and corrected the amount of water supplied based on the intuition. ing. However, this method cannot avoid fluctuations due to the physical condition of the operator, and also tends to cause errors due to individual differences due to replacement of operators.

The slump value is an index showing the workability of concrete, that is, the fluidity, and is known to be correlated with the load power of the mixer when kneading concrete. Therefore, a method of using this correlation and adjusting the amount of water using the load power of the mixer as a parameter is used.

In this method, the load power is measured at the time when the load power of the mixer is stable, that is, when the kneading is sufficiently performed, and the amount of water is adjusted based on the measured value.
Therefore, it is inevitable that there will be a time delay, and especially in the situation where the time required for kneading concrete is significantly shortened due to the improvement of mixer performance in recent years, it is necessary to eliminate the time delay as in the past as much as possible. There is.

The present invention has been made in view of the above circumstances, and an object thereof is to accurately supply the amount of water in accordance with the mixing ratio by accurately measuring the water content in all states of the aggregate.

[0015]

Means for Solving the Problems When the moisture value of an aggregate is measured, the present inventor has found that the aggregate can be used in any of an absolutely dry state, an air dry state, a surface dry state and a wet state. By using a moisture meter that can accurately detect the water content of the aggregate, and by measuring the water content in all states of the aggregate, we have found that the amount of water according to the set mixing ratio can be accurately supplied.

Therefore, as a result of collecting and experimenting with various moisture meters, a high-precision moisture meter sensor capable of detecting moisture values in all the states of the above-mentioned aggregate was discovered, and its installation position and the like were studied. As a result, the present invention is configured as follows to achieve the above object.

A weighing hopper provided under the aggregate storage bin via a natural fall path, a mixer for kneading cement, water, and the aggregate supplied from the weighing hopper, and a crossing path for the fall path. It is provided as an and dry, air-dried,
Ready-mixed concrete provided with a high-precision moisture meter sensor capable of measuring aggregates in both a dry state and a wet state, and a control device to which measurement data of the weighing hopper and the high-precision moisture meter sensor are input. In the kneading system, the controller calculates a preset aggregate weight and a water supply amount based on the measurement data from the high-precision moisture meter sensor, and also sets the preset aggregate weight and water. A kneading system for ready-mixed concrete, which is characterized by correcting the supply amount of.

[0018]

[Operation] Aggregate supplied from the aggregate storage bin into the free fall path collides with the high-precision moisture meter sensor while maintaining a constant porosity, and after the moisture value is measured, it enters the aggregate weighing hopper. To fall. The measurement data of the moisture meter sensor and the measurement data of the aggregate weighing hopper are input to the control device, and the control device corrects the preset aggregate weight and water supply amount based on the measurement data. .

[0019]

Embodiments of the present invention will be described with reference to the accompanying drawings. In the factory F, aggregate storage bins 1, 2, 3 and belt conveyors 5, 6, 7 and high-precision moisture meter sensors 9, 10, 11 and weighing hoppers 12, 13, 14 and a mixer 16 are arranged. .

The aggregate storage bins 1 and 2 store coarse aggregate, for example, gravel Z, and the aggregate storage bin 3 is fine aggregate, for example, sand S.
Are stored.

The upper end 5a of the belt conveyor 5 is located above the weighing hopper 12, and a free fall path 20 is formed between the upper end 5a of the belt conveyor and the weighing hopper 12.

The length H of the free fall path 20 is appropriately selected according to need. For example, the length H is 20 to 40.
cm is adopted.

A high-precision moisture meter sensor 9 is provided in the free fall path 20 so as to intersect with each other. The crossing angle θ is appropriately determined as needed. For example, the crossing angle θ is 90 degrees. Be done. The installation height L of the sensor 9 is set so that the moisture sensor 9 is on the aggregate weighing hopper side. For example, a height of 5 cm from the upper surface 11a of the aggregate weighing hopper 11 is selected.

The reason for setting the moisture meter sensor 9 at such an installation height is as follows. When the moisture value of the aggregate M is measured near the belt conveyor 5, the moisture value may change and the moisture value may change during the fall to the aggregate weighing hopper. Therefore, aggregate M should be as close to the aggregate measurement hopper as possible.
It is necessary to measure the water content of the aggregate in order to obtain the accurate water content of the aggregate.

As the high precision moisture meter sensor 9, a microwave high precision moisture meter is used. This moisture meter irradiates microwaves and detects and measures the amount of energy absorbed. The amount of microwaves absorbed by water molecules is converted into a moisture value (%) by the following formula. V = Ae- ^PM

In this equation, V is the output voltage from the sensor, M is the moisture value of the substance, A is the measurement value in the dry state, P is the measurement value in the intermediate zone and the measurement value is high.
Are shown respectively.

When the same aggregate is sampled two or more times and its moisture value (%) and V value are input to the unit, the A and P values are calculated and the curve shown in FIG. 4 is obtained.

In FIG. 4, the curve a is V = 8e- ^0.1M ,
Curve b is V = 8e ^-0.2M , Curve C is V = 8e ^-0.3M , Curve d is V = 9e ^-0.1M , Curve e is V = 9e ^-0.2M , Curve f is V = 10e ^-0.1M , The relationship between the voltage V and the water content (%) at the time is shown. As an example, in curve a, when the voltage is 8V,
The water content is 0%, and the water content is 5% when the voltage is 5V.

The moisture meter 9 comprises a ceramic plate 9a.
It is equipped with a sturdy stainless steel box 9b and a flange 9d to which microwave energy is radiated through the plate 9a, on which the DUT flows.

The microwave high precision moisture meter 9 includes a cable 9
It is connected to the control device (measurement operation panel) 30 via c. The moisture meter 9 has a frequency of 0.3 to 1.2 GH.
Z, power supply 100MA + 15V, 5MA -1
It is operated at 5V.

The weighing hoppers 11 and 12 are for coarse aggregate Z, the weighing hopper 13 is for fine aggregate S, and the weighing hopper 14 is cement C.
And weighing hopper 15 is a weighing hopper for water W. These weighing hoppers 12 to 15 are connected to the control device 30.

The weighing hoppers 11 to 14 are made of aggregates Z and S.
It is connected to the mixer 16 for kneading the cement C and the water W.

Hoppers 2, 3 for coarse aggregate Z and fine aggregate S,
Belt conveyors 6, 7, high-precision moisture meter sensors 10, 1
1. The weighing hoppers 12 and 13 are also the same as above, and thus detailed description thereof will be omitted.

The cement C is conveyed to the weighing hopper 14 by a screw conveyor (not shown) and its weight is measured, and then the cement C is put into the mixer 16 and the measurement data is transmitted to the control device 30.

The water W is supplied from a water supply facility (not shown) to the weighing hopper 15, the weight of the water W is measured, the water W is injected into the mixer 16, and the measurement data is transmitted to the control device 30.

The control device 30 calculates the weight of the aggregate and the amount of water based on the measurement data of the microwave high precision moisture meters 9, 10 and 11, and corrects the preset water supply amount. Aggregate storage bins 1-3 gates, belt conveyors 5-7 switches, weighing hoppers 12-15 gates,
Controls the screw conveyor switch, water supply equipment switch, etc.

The controller 30 is connected to a personal computer 31 of an office G, which is remote from the factory F, via an optical modem 32. Mixing instructions are given to the ready-mixed concrete mixing system in the factory F via the personal computer 31, and information such as the mixing status in the factory F is transmitted to the personal computer 31 via the control device 30.
Sent to.

The mixer 16 is connected to a concrete hopper 34 via a skip hoist 33.
The fresh concrete is supplied from the mold to the molding step 40, and concrete products such as blocks are manufactured.

The operation of this embodiment will be described. When the operation is started after the personal computer 31 gives the controller 30 a compounding instruction of the set aggregate weights Zo and So, the set cement weight Co, and the set water weight Wo in the surface dry state, the aggregate in the aggregate storage hopper 1 is started. Z is conveyed by the belt conveyor 5 onto the weighing hopper, and falls from its tip 5a into the natural falling path 20 by its own weight while being separated. At this time, the III-III line cross section of the free fall path 20 becomes as shown in FIG. 3, and the aggregate Z falls while maintaining a substantially uniform porosity and collides with the moisture meter 9.

Microwave energy is radiated from the plate 9a of the moisture meter 9, and the moisture of the aggregate absorbs the microwave when the aggregate Z passes therethrough. The moisture value of the aggregate is calculated by converting this energy absorption amount into the moisture value (%) in the above-described manner.

As described above, the moisture meter 9 can continuously detect the moisture value in all the states of the aggregate.
The measurement by the moisture meter 9 is continued from the start of the aggregate supply from the aggregate storage bin 1 to the weighing hopper 12 until just before the weight of the weighing hopper 12 reaches the set weight Zo. This measurement time is appropriately selected according to need. For example, when the aggregate set weight Zo is 1t, 90% of the weight is set, that is, 990.
It is performed until it reaches kg.

The controller 30 obtains the average of the moisture values of the aggregate Z on the basis of the information from the moisture meter 9, obtains the aggregate weight db corresponding to the moisture value in the aggregate weight Zb, and sets the aggregate weight Zo. The weight db is added to and the corrected aggregate weight Za is obtained.

When the measured value of the weighing hopper 12 reaches the corrected aggregate set weight Za, the gate of the aggregate storage hopper 1 is closed according to the instruction of the control device 30, and the belt conveyor 5 is stopped.

The aggregates Z and S of the aggregate storage hoppers 2 and 3 are the same as the aggregate Z of the aggregate storage hopper 1, and the moisture meters 10 and 1 are used.
Weighing hoppers 12 and 13 while measuring the water content by
And the amount of supply is controlled.

The cement C is conveyed to the weighing hopper 14 via the screw conveyor 26, and the cement set weight C is set.
When the temperature reaches o, the control device 30 gives an instruction to stop the supply and stops the screw conveyor 26.

The controller 30 subtracts the water amounts Wz and Ws of the aggregates Z and S from the water set weight Wo of the set mixture ratio, adds the supplemental water amount Wh to the value, and corrects the water setting. The weight Wb is calculated. This supplemental water amount Wh takes into consideration that the mixing ratio is determined based on the aggregate in the surface dry state. That is, the aggregate in the completely dry state and the air dried state is
Since extra water, that is, supplemental water Wh is required before reaching the surface dry state, this supplemental water Wh is calculated based on the water absorption of the aggregate, and the water weight is included in the water set weight Wo. , To obtain an accurate blending ratio. This set water weight Wb is the weight of water to be supplied from the water supply facility. The controller 30 stops the water supply when the water W in the weighing hopper 15 reaches the weight Wb.

When the weight of each weighing hopper reaches the above-mentioned measured value as described above, the control device 30 causes the weighing hopper 12 to operate.
Open the gates of ~ 15 and supply them into the mixer 16 and knead them. At this time, the aggregate Z supplied into the mixer 16,
Since S, cement C, and water W have an ideal mixture ratio, the kneaded ready-mixed concrete has a required slump value.

After the mixing is completed, the ready-mixed concrete is mixed in the mixer 16
Is discharged to the concrete hopper 34 through the skip hoist 33. One cycle is completed through the above steps, but this cycle is repeated as many times as necessary.

Another embodiment of the present invention will be described with reference to FIG. 7. The difference between this embodiment and the above embodiment is as follows. (1) The set weight of the aggregate and the water supply amount are calculated in advance based on the absolutely dry state of the aggregate, and the water supply amount is corrected by taking the water absorption rate of the aggregate into consideration. (2) There is no water measuring hopper, and the supply of water into the mixer 16 is controlled by the flow meter 51 and the electromagnetic valve 52 according to an instruction from the control device 30. The injection of this water into the mixer is performed after the aggregates Z and S and the cement C have been mixed to some extent by the mixer 16. (3) The ready-mixed concrete in the concrete hopper 34 is loaded on the ready-mixed concrete transport vehicle 53 instead of being supplied to the molding process, and is transported to a predetermined place and placed. (4) Aggregates Z and S of the aggregate storage hoppers 1 and 2 are mixed and fall into the free fall path 20, and while the moisture value is measured by one microwave high-precision moisture meter 9, coarse aggregate and fine aggregate The material drops into the weighing hopper 56, and the weight is measured by the weighing hopper 56. (5) The cement C is conveyed to the weighing hopper 14 by the belt conveyor 58 instead of the screw conveyor.

[0050]

Since the present invention is configured as described above, it has the following remarkable effects. (1) Since a high-precision moisture meter sensor that can measure the aggregate in all the dry, air-dried, surface-dried and wet-dried states is used, the moisture value in all the aggregates can be measured. The amount of water to be supplied can be accurately calculated based on the measured data, and the ideal blending ratio can be obtained. Therefore, it is possible to obtain concrete excellent in required workability, strength, durability, uniformity and the like. (2) Since the high-precision moisture meter sensor is provided in the free fall path so as to intersect, the moisture value of the aggregate flowing down the drop path with a substantially uniform porosity can be measured. Therefore, the accurate moisture value can be measured. Also, this sensor can be easily attached to existing equipment without any special work. (3) Based on the measurement data of the high-precision moisture meter sensor from the start of the supply of aggregate into the weighing hopper to immediately before the set supply amount,
Since the set supply amount of aggregate and the set supply amount of water are corrected, correction can be performed with high accuracy without waiting time. Therefore, without stopping the kneading system,
It is possible to efficiently obtain ready-mixed concrete having a desired slump value.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a diagram showing a relationship between a voltage V and a moisture content% of a microwave high precision moisture meter.

FIG. 5 is a perspective view of a microwave high precision moisture meter.

FIG. 6 is a diagram showing various states of an aggregate.

FIG. 7 is a diagram showing another embodiment.

[Explanation of symbols]

 1 Aggregate storage bin 2 Aggregate storage bin 3 Aggregate storage bin 9 Microwave high precision moisture meter 10 Microwave high precision moisture meter 11 Microwave high precision moisture meter 12 Aggregate weighing hopper 13 Aggregate weighing hopper 14 Cement weighing hopper 15 Water weighing Hopper 16 Mixer 20 Free fall path 30 Controller

Claims (5)

[Claims] 1. A weighing hopper provided at a lower part of an aggregate storage bin via a natural fall path, a mixer for kneading cement, water, and an aggregate supplied from the weighing hopper, and the drop flow path. It is installed crossing and is in an absolutely dry state, an air dried state,
A raw material provided with a high-precision moisture meter sensor capable of measuring aggregates in both a dry state and a wet state, and a control device to which each measurement data of the weighing hopper and the high-precision moisture meter sensor is input. A concrete kneading system, wherein the controller calculates the aggregate weight and the amount of water based on the measurement data from the high-precision moisture meter sensor, and the preset aggregate weight and the water supply amount. A kneading system for ready-mixed concrete, which is characterized by correcting 2. A kneading system for ready-mixed concrete, wherein a preset correction of the aggregate weight and the supply amount of water is performed on the basis of the aggregate weight in a surface dry state. 3. The raw material is characterized in that the preset weight of the aggregate and the amount of water supplied are corrected on the basis of the weight of the aggregate in an absolutely dry state, and the water absorption rate of the aggregate is taken into consideration. Concrete kneading system. 4. The preset correction of the aggregate weight and the water supply amount is based on the measurement data of the high-precision moisture meter sensor from the start of the supply of the aggregate into the weighing hopper until just before the set aggregate weight. The kneading system for ready-mixed concrete according to claim 1, 2, or 3, which is performed. 5. The kneading system for ready-mixed concrete according to claim 1, 2, 3, or 4, wherein the high-precision moisture meter sensor is a microwave high-precision moisture meter.