JPH0711188B2 - Control method and device for detecting blockage in pipe of concrete pump method using electric characteristics of fresh concrete - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fresh concrete discharged from a pump (fresh concrete is a fluid in which coarse aggregate, fine aggregate, cement and water are mixed). Coarse aggregates and fine aggregates are collectively referred to as aggregates below.), A fresh concrete transportation device that is transported by a pressure pipe (hereinafter referred to as a concrete pump method)
Relates to a blockage detection control method and device for the purpose of preventing a blockage accident of concrete in a pumping pipe.

[Prior Art] When pouring a reinforced concrete structure or the like, there is a concrete pump method as one of means for transporting fresh concrete from a concrete mixer truck or the like to a pouring site. This method is a method in which fresh concrete is discharged from a pump, and the discharge pressure causes the fresh concrete to be pressure-fed to a pouring position through a pressure-feeding pipe. This concrete pump construction method is widely used in the fields of civil engineering and construction because it is more effective in saving labor during construction, shortening the construction period, and reducing the construction cost compared to the conventional construction method in which concrete is conveyed batch by truck. Has been done.

[Problems to be Solved by the Invention] However, the relationship between the fluidity of concrete and the transport capacity of the pump in the concrete pump method has not yet been sufficiently clarified, and when the aggregate-volume ratio of concrete is high. In particular, a blocking accident may occur in which the aggregate blocks the pumping pipe. In order to avoid this blockage accident, increase the percentage of fine aggregate in fresh concrete, or increase the unit water amount (water amount per unit volume) or unit cement amount (cement amount per unit volume), that is, the coarse aggregate. It is practiced to reduce the volume ratio of aggregate to increase the fluidity of concrete. However, an increase in the unit water amount or unit cement amount causes defects such as many cracks in the concrete after construction and deterioration of durability or appearance.

The present invention has been made in response to the above-mentioned problems in the concrete pump construction method, and the purpose thereof is to detect early the occurrence of the blockage phenomenon in the pressure feeding pipe, and When it is detected, the blockage releasing device is driven to prevent or release the blockage accident, thereby facilitating the transport of fresh concrete, and at the same time, enabling the transport of fresh concrete having a high aggregate volume ratio, and a method for preventing blockage of a pumping pipe, and It is to provide a device.

[Means for Solving Problems] As a result of a pumping test and a plugging test of fresh concrete using a small pump and a taper pipe, it was confirmed that the following various phenomena appear as precursors of the plugging phenomenon. That is,
When a blockage phenomenon occurs in the pumping pipe, material separation of fresh concrete occurs before the blockage,
The transport speed of coarse aggregate is lower than the transport speed of mortar (mortar refers to the part other than coarse aggregate in concrete), the interval between coarse aggregates narrows, and eventually the mutual interval does not change. The phenomenon that they do not move, mesh with each other, and suddenly stop moving appears. At this time, the coarse aggregate often forms a toroidal arch having a top in the direction of the pump and a bottom in the direction to be transported, and the frictional and compressive forces between the coarse aggregates cause pumping. Against the discharge pressure of.

It was also confirmed by experiments that the impedance of fresh concrete changes depending on the volume ratio of coarse aggregate in fresh concrete, because the electrical conductivity of coarse aggregate differs from that of mortar.

Therefore, the fact that the coarse aggregate did not move as described above during the pressure-feeding pipe due to the material separation was detected by the change in the electrical impedance of the fresh concrete based on the change in the volume ratio of the coarse-aggregate. If the immobile state or the arch is destroyed by shaking, it becomes possible to prevent or release the blockage of the pressure feeding pipe.

In the method and apparatus for preventing blockage of a concrete pumping pipe according to the present invention, the above-mentioned problems in the concrete pump method are solved by using the method and the apparatus as the method or apparatus configured as follows. ing.

That is, in the invention of the method, the method is (a)
The impedance of the fresh concrete in the pumping pipe is measured, (b) the volume ratio of the aggregate in the fresh concrete or the rate of change of the volume ratio is calculated based on the impedance, and (c) the volume ratio of the aggregate or the change of the volume ratio. When the rate exceeds a certain value, the pipe clogging detection control method of the concrete pump construction method using the electric characteristics of fresh concrete to prevent the clogging of the pressure feeding pipe or to release the clogging by vibrating the pressure feeding pipe is provided.

Further, in the invention of the device, the device is provided with (a) an impedance measuring unit for measuring impedance of fresh concrete between electrodes facing each other at a constant interval in a pressure feed pipe. And (b) a volume ratio calculating unit for calculating an aggregate volume ratio in fresh concrete based on the impedance, and (c) vibrating the pressure-feeding pipe when the aggregate volume ratio exceeds a certain value. A pipe clogging detection control device for a concrete pump method utilizing electric characteristics of fresh concrete, which comprises a vibrating device for preventing or canceling clogging.

[Embodiment] A method and apparatus for preventing blockage of a pressure feeding pipe according to the present invention will be described with reference to FIGS. 1 (A), (B) and FIG.

FIG. 1 (A) is a conceptual diagram showing a method of calculating the volume ratio of coarse aggregate in the pressure-feeding pipe based on the measurement of the electrical impedance. In the figure, the parts of the pressure-feeding pipe and the fresh concrete are A cross section perpendicular to the axial direction of the pressure feed pipe is shown. Further, FIG. 1 (B) is a conceptual diagram showing the pressure feeding pipe as viewed from the side surface. In FIGS. 1 (A) and 1 (B), reference numeral 1 is a pressure pipe, 2 is fresh concrete, 3a, 3b, 3c, 3d are electrode plates, 4 is a power supply, 5 is a voltmeter, and 6 is a constant resistance. , 7 are impedance measuring units.
Fresh concrete 2 is gravel 8 which is coarse aggregate.
It is a mixture of sand, which is a fine aggregate, cement, and water. The electrode plates 3a, 3b, 3c, 3d are all electrically insulated from the pressure feed pipe 1. As shown in FIG. 1 (A), a power source 4, electrode plates 3c and 3d, fresh concrete, electrode plates 3a and 3b, and an impedance measuring unit 7 (the impedance measuring unit 7 is a voltage connected in parallel). (Provided with a total of 5 and a constant resistance 6) constitutes an electric circuit.

Hereinafter, the method for detecting blockage of the pressure feed pipe used in the present invention will be described.

In FIG. 1 (A), when the power source 4 applies a steady voltage, a steady current flows in the electric circuit. This current flows through the fresh concrete between the electrode plates 3a, 3b and the electrode plates 3c, 3d. On the other hand, the voltmeter 5 measures the potential difference across the constant resistance 6. By the way, electrode plate
If the coarse aggregate does not move between 3a, 3b and the electrode plates 3c, 3d and the volume ratio of the coarse aggregate in the fresh concrete changes, it is due to the difference in electrical conductivity between the coarse aggregate and the mortar part. Then, the impedance between both electrodes changes. This change in impedance is detected by the voltmeter 5 as a change in potential difference across the constant resistance 6. Therefore, the impedance measuring unit 7 calculates the coarse aggregate volume ratio based on the relationship between the coarse aggregate volume ratio and the impedance of the electric circuit, which has been grasped in advance by experiments or the like.

In this way, by calculating the coarse aggregate density from the change in impedance, it is possible to detect the precursor of the occlusion phenomenon or the occurrence of the occlusion phenomenon.

FIG. 2 is a conceptual diagram showing a blockage prevention device for a pressure feeding pipe.
In FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, reference numeral 9 is a volume ratio calculation unit, 10 is a vibration control unit 11, and a vibration source 12
And a flexible ring (13). The vibrating device 10 is located near the electrode plates 3a, 3b, 3c, 3d.

The impedance measuring unit 7 supplies a signal regarding the measured impedance to the volume ratio calculating unit 9. The volume ratio calculation unit 9 calculates the coarse aggregate volume ratio of the fresh concrete in the pumping pipe based on this signal, and when the coarse aggregate volume ratio exceeds a certain value, it is activated for the vibration device 10. Supply a signal. The time point when the volume ratio of the coarse aggregate exceeds a certain value corresponds to the time point when the pressure feeding tube starts to be blocked or when the blockage occurs. In the vibration device 10, the vibration control unit 11
The drive signal is supplied to the vibration source 12,
Is a flexible ring that fastens the pressure pipe from the surroundings.
Excitate 13. This flexible ring 13 vibrates the pumping pipe 1, and this vibration destroys the arch-like structure of the coarse aggregate that causes the blockage, and the blockage is released.

In FIG. 2, a flexible ring is used as the vibration source, but other vibration sources (vibrator or a method of giving an impact) can also be used.

As described above, according to the method and the device for preventing obstruction of the pressure feeding pipe according to the present embodiment, the occurrence of the obstruction phenomenon in the pressure feeding pipe is detected at an early stage, and the vibration device is driven to prevent or cancel the obstruction accident. Therefore, the transport of fresh concrete can be facilitated and the transport of fresh concrete having a high aggregate volume ratio can be enabled.

In this embodiment, the opposing electrodes are two sets of opposing electrode plates, but may be one pair of opposing electrode plates or three or more opposing electrode plates.

Further, in the present embodiment, the vibrating device is driven when the coarse aggregate density exceeds a certain value, but for the coarse aggregate density, an average value is obtained for a time section having a certain width. The vibration device may be driven when the average value exceeds a certain value.

Further, in the present embodiment, the electrode plate is provided only at one position and the aggregate density is calculated at that position. However, the electrode plates are provided at two or more positions and the aggregate density is calculated at each position. Alternatively, the vibrating device may be driven by the occurrence of the blockage phenomenon at any position.

[Effects of the Invention] According to the method and the device for preventing obstruction of the pressure feeding pipe according to the present embodiment, the occurrence of the obstruction phenomenon in the pressure feeding pipe is detected at an early stage,
When the phenomenon is detected, the vibrating device can be driven to prevent or cancel the blockage accident, thereby facilitating the transportation of fresh concrete. Further, since the change in quality can be grasped by measuring the impedance, quality control becomes possible. Furthermore, it is possible to enable transportation of fresh concrete having a high aggregate volume ratio.

[Brief description of drawings]

FIGS. 1 (A), (B) and FIG. 2 are views for explaining a method and a device for preventing blockage of a pressure feeding pipe according to the present invention,
1 (A) and 1 (B) are conceptual diagrams showing a method for calculating the volume ratio of coarse aggregate in the pressure-feeding pipe based on the measurement of electrical impedance, and FIG. 2 shows a blockage preventing device for the pressure-feeding pipe. It is a conceptual diagram shown. 1 ... Pumping pipe, 2 ... Fresh concrete, 3a, 3b,
3c, 3d ... Electrode plate, 7 ... Impedance measurement section, 9 ...
… Volume ratio calculator, 10 …… Vibration device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shusuke Harada 585, Tomimachi, Funabashi City, Chiba (56) References JP-A-63-223264 (JP, A) Jitsuko Shou 51-37212 (JP, Y2)

Claims (2)

[Claims] 1. A fresh concrete transporting device for transporting fresh concrete discharged from a pump by a pumping pipe, wherein (a) the impedance of the fresh concrete in the pumping pipe is measured, and (b) the fresh concrete is based on the impedance. The volume ratio of the aggregate in the inside is calculated, and (c) when the volume ratio of the aggregate exceeds a certain value, the electrical characteristics of the fresh concrete for vibrating the pressure-feeding pipe to prevent or unblock the pressure-feeding pipe are determined. A method for controlling the detection of blockages in pipes of the concrete pump method used. 2. A fresh concrete transporting device for transporting fresh concrete discharged from a pump by means of a pressure-feeding pipe, wherein (a) the pressure-feeding pipe has electrodes facing each other at regular intervals, and between the electrodes facing each other. An impedance measuring unit for measuring impedance of fresh concrete, (b) a volume ratio calculating unit for calculating an aggregate volume ratio in the fresh concrete based on the impedance, and (c) a constant aggregate volume ratio And a vibrating device for preventing or canceling the blockage by vibrating the pressure-feeding pipe when the temperature exceeds the limit. A pipe blockage detection control device for a concrete pump construction method using electric characteristics of fresh concrete.