JP2858725B2 - Surface water detection method for concrete in formwork - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting surface water of concrete in a formwork, and more particularly, to detecting surface water staying on the top surface of concrete in a corner portion, a lower surface of a top cover, or the like in the formwork which is difficult to see. The present invention relates to a method for detecting surface water of concrete in a formwork, which contributes to an accurate determination of a concrete filling condition at a concrete pouring stage.

[0002] Here, "concrete surface water" (hereinafter sometimes referred to as surface water) refers to water remaining in a mold after water washing and water generated by breathing or the like remaining on the concrete surface. Say.

[0003]

2. Description of the Related Art In order to reliably detect concrete filling on a concrete surface in a formwork, the present applicant has proposed a concrete filling detecting method using an electrode in Japanese Patent Application No. 5-175682. This detection method will be briefly described with reference to FIG. 7 to the extent necessary for understanding the present invention.

An electrode 35 made of a thin insulating sheet 7 to which electric contacts 5 and 6 with leads 17 are attached is disposed in the concrete form 1 in the vicinity of the plate member 2. When the concrete is cast, the conduction between the electrical contacts 5 and 6 by the concrete 20 is detected by the current flowing through the ammeter 13 connected between the power supply 22 and the electrical contacts 5 and 6, and the concrete structure to be cast Detecting the filling of the concrete 20 in the above-mentioned nearby portion where the surface of the object is to be formed. On the other hand, if the air pocket 8 remains on the concrete surface 12 at the location of the electrode 35, no continuity occurs between the electrical contacts 5 and 6, so that the ammeter 13
Unfilled concrete can be detected by the fact that no current flows in In order to prevent the air pool 8, the air vent 9
And air is released as indicated by arrow A. In the above conventional example, the ammeter 13 substantially detects only the presence or absence of conduction based on the presence or absence of a current of a predetermined value or more, and it has been proposed to replace the ammeter 13 with a light emitting diode.

[0005]

In the conventional detection of concrete filling based on the presence or absence of a current exceeding a predetermined value in an ammeter or a light emitting diode, when there is surface water on the top surface of cast concrete, the electric resistance of the surface water is reduced. Is much smaller than that of air, there is a risk that such surface water may be erroneously determined to be concrete, and the drawback that reliability of concrete filling detection is impaired is inevitable.

According to the results of various experiments and measurements on the resistance value of concrete and surface water, the actual resistance value of concrete changes and varies depending on the concrete mixing conditions, concrete placing conditions, environmental conditions, and the like. It is recognized that there is a large variation in the resistance value of the mixture of only cement and water, and that there is a large fluctuation range in the resistance value of the concrete surface water.

FIG. 6 shows that it is difficult to reliably distinguish concrete and surface water based on the magnitude of the resistance value. In the figure, the horizontal axis is the resistance value, and the vertical axis is the number of samples. Since the resistance value of the shaded portion in this figure can be taken by both concrete and surface water, it is not possible to distinguish between concrete and surface water only by the resistance value of this portion.

The importance of detecting surface water in a mold will be described with reference to FIG. In the case of protection of the metal tub 25 by the concrete lining 26, for example a shielding concrete wall in which the radiation is attenuated in the concrete lining 26, the concrete thickness D in FIG. 2C determines the effectiveness of the shielding. A void 29 is formed in the concrete lining 26 for some reason. Even if the depth H is small and the width L is large, the concrete 29 effective for shielding is used.
The effective width of the lining 26 is reduced to (DL), and the shielding effect is significantly impaired. Such voids 29 are used, for example, when forming a concrete lining 26 such as to embed a metal tube 27 horizontally connected to a metal tank 25, so that the concrete 20 in the form 1 (see FIG. Exists along the surface of the metal tube 27, and is generated when the surface water 21 disappears due to evaporation or leaching after the concrete 20 condenses. Such a small amount of surface water 21 may impair the shielding function of the concrete lining 26 when the surface water 21 remains wide and shallow on the top surface of the concrete 20 even if its amount is small. Therefore, development of a method for clearly distinguishing surface water from concrete is strongly expected.

An object of the present invention is to provide a method for detecting surface water of concrete in a formwork by changing the resistance value over time in order to meet this expectation.

[0010]

SUMMARY OF THE INVENTION The present inventor has determined that, for concrete having substantially the same composition, which is put into a specific concrete form in one casting operation, the concrete-filled portion and the surface are filled with concrete. It was noticed that a difference in resistance value occurred with water. That is, there is a clear difference in resistance between the portion where the concrete of the specific composition is filled in a solid state and the surface water of the concrete of the specific composition. FIG.
Referring to (A) to FIG. 1 (C), when concrete having substantially the same composition made by one kneading operation is poured, concrete 20 is always filled in the concrete form 1 in a solid state. The change over time in the resistance value at the part is due to the high resistance of air before casting concrete 20
Tracing a history like curve C which reaches a medium resistance of the filled concrete 20 through the low resistance of the concrete. The vertical axis of FIG. 1 (C) indicates the resistance value of the measurement part. On the other hand, when the concrete 20 is not completely filled in other portions in the concrete form 1 and the surface water 21 remains, the change with time in the resistance value of that portion is represented by the curve M in FIG. And the resistance value of the concrete 20 stays at or near the surface water resistance value and does not increase to the resistance value of the concrete 20.

Therefore, the temporal change of the resistance value when the concrete 20 is cast in a portion where the concrete 20 in the form 1 is always filled is recorded, and the concrete is filled in the form 1 immediately thereafter. By measuring the change with time of the resistance value in the portion to be filled, and comparing the change with time of the measured resistance value with the change with time of the stored resistance value, the surface that can be generated in the portion to be filled immediately after the above It is possible to detect the remaining water 21, that is, the unfilled concrete. Rather than comparing the absolute value of the resistance value, using the relative comparison between the history curve of the resistance change when the concrete is completely filled and the history curve of the resistance change when the surface water remains, the concrete surface water Can be reliably detected, that is, the state where concrete is not filled.

According to the method for detecting surface water of concrete in a formwork of the present invention, a measuring electrode 4 is mounted on a predetermined portion of the inner surface of a concrete form 1 and a calibration electrode 3 is mounted on a wide smooth inner surface of the form below the predetermined portion. The change over time of the resistance value of the concrete 20 by the calibration electrode 3 at the time of placing the concrete 20 on the smooth mold inner surface is shown by a curve C in FIG. After recorded measured, concrete to said predetermined portion
Temporal change in the resistance of the concrete 20 by the measuring electrode 4 on hitting設時adversaries 20, changes over time such as the curve M in example FIG. 1 (C) was measured over time of the resistance value in the calibration electrode 3 The difference between the change in the resistance value and the change in the resistance value of the measurement electrode 4 over time is caused by the concrete 20
Surface water 21 is detected.

Here, the predetermined portion in the concrete form 1 means that it is difficult for the poured concrete 20 to go around, for example, at the lower corner of the rib portion 2A in FIG. This is a part that requires confirmation of the presence of water and concrete filling. In addition, "the wide smooth formwork inner surface"
When concrete 20 is put into form 1, concrete 20
Means a wide and smooth inner surface of the mold that always forms a filled portion.

[0014]

FIG. 1B shows an example of a circuit for measuring the change over time in the resistance between the calibration electrode 3 or the measuring electrode 4 and the concrete 20 in the formwork. In this case, the plate member 2 of the mold 1 is made of metal and acts as one electrode that comes into contact with the concrete 20, and the calibration electrode 3 is connected to the electrical contact 5 on the insulating sheet 7 fixed to the inner surface of the plate member 2. The description will be made assuming that the measurement electrode 4 is composed of the electrical contact 5A on the similar insulating sheet 7A. However, the present invention is not limited to the mold 1 made of the metal plate member 2 in the illustrated example, the calibration electrode 3 and the measurement electrode 4 in the illustrated structure. If the voltage of the power supply 22 is applied between the metal plate member 2 and the electric contact 5 of the calibration electrode 3 via the ammeter 13 and / or the light emitting diode 15 in this case, it is equivalent to a variable resistance in FIG. The change of the resistance value in the space 10 in the plate member 2 can be measured by reading the current i of the ammeter 13.

A curve C in FIG. 1C shows a change in a resistance value which is a reciprocal of the current value. That is, when the space 10 is only air, the resistance value is large (infinite). For example, the concrete 20 fills the space between the plate member 2 and the electric contact 5 of the calibration electrode 3 when the time T ₀ elapses from the start of concrete casting. Then, since the resistance value of the concrete becomes medium, the current value becomes medium. If the surface water 21 exists between the plate member 2 and the electrical contact 5 of the calibration electrode 3 at an intermediate stage, the surface water 21
The resistance value of the calibration electrode 3 is smaller than that of concrete.
The resistance value measured under the above condition also becomes smaller, and the curve C under this condition becomes smaller.
Has a form with a minimal resistance value. The level T in the figure indicates a medium resistance value indicating the filling of the concrete 20, that is, a threshold value for the concrete filling.

A curve M in FIG. 1C shows an ammeter 13 when the voltage of the power supply 22 is applied between the metal plate member 2 and the electric contact 5A of the measuring electrode 4 in the same manner as in the case of the curve C. Of the resistance value, which is the reciprocal of reading the current i. In the case of the curve M, the air is replaced by a substance having a very low resistance such as surface water 21 at the position of the measuring electrode 4, but the resistance value does not reach the threshold value T because the concrete 20 is not filled. . Therefore, if it is detected that there is a difference between the curves C and M, it is possible to detect that the surface water 21 remains, that is, the concrete is not filled, based on the difference. On the other hand,
When the concrete 20 is filled at the site of the measurement electrode 4, the same result as that of the curve C is obtained with the measurement electrode 4, and it is apparent that there is no difference between the curves C and M.

Thus, the object of the present invention to provide a "method of discriminating the filling of the concrete surface in the formwork by the change over time of the resistance value" is achieved.

When the brightness of the light emitting diode 15 changes according to the magnitude of the passing current, and when the change in the brightness can be distinguished from the filling of the concrete 20 by observing the change in the brightness, the ammeter 13 can be omitted. .

When the remaining surface water 21 is detected, that is, when the unfilled portion of the concrete is detected, the concrete is vibrated by using a vibrator (not shown) or the like to drive the surface water 21 out of the mold 1 and to displace the plate member 2. Up to the entire surface of the concrete
Fill 20 to ensure good concrete placement. FIG.
The chain line curve V in (C) indicates the surface water 21 due to a vibrator or the like.
And the realization of concrete filling.

When the plate member 2 is not made of metal but made of wood, for example, a counter electrode (not shown) serving as a counter electrode of the calibration electrode 3 and the measurement electrode 4 is provided on the inner surface of the mold 1 below the calibration electrode 3. Can be mounted on Further, as shown in FIG. 7 (C), a pair of contacts 5, 6 are provided on each of the calibration electrode 3 and the measurement electrode 4.
And a structure in which a lead wire 17 is connected to each contact may be used. In this case, the resistance value between the calibration electrode 3 or the measurement electrode 4 and the concrete 20 in the mold 1 can be obtained by measuring the resistance value between the pair of contacts 5 and 6.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a structure in which a surface unfilled with concrete tends to remain, a joint portion between a metal tank 25 and a metal pipe 27 in a concrete lining 26 with respect to a metal tank 25 is shown in FIG.
Shown in FIG. 2A shows the arrangement of the gusset plate 28 at the end of the metal tube 27 of the metal tube 27 by cutting out a part of the concrete lining 26, and FIG. 2B shows the arrow of FIG. FIG. 4 is an enlarged view of a main part viewed from a direction B, showing an example of arrangement of a calibration electrode 3 and a measurement electrode 4 for detecting unfilled concrete. In this case, the vertical wall surface of the metal tank 25 corresponds to the vertical portion of the metal plate member 2 of the mold 1 in FIG. 1A, and the lower surface of the metal tube 27 corresponds to the rib 2A in FIG. 1A. At the intersection between the vertical wall surface of the metal tank 25 and the lower surface of the metal tube 27, surface water remains, that is, unfilled concrete is likely to occur.
In order to reliably detect unfilled concrete in this part and take countermeasures using a vibrator or the like, the calibration electrode 3 is mounted on the vertical wall surface of the metal tank 25 near the joint with the metal tube 27, and the lower part of the metal tube 27 is mounted. The measurement electrode 4 is mounted on the surface near the joint with the metal tank 25.

Referring to FIGS. 3 and 4, there are a plurality of portions (A, B,...,
L) In some cases, a pair of a calibration electrode and a measurement electrode 3 _A , 4 _A ; 3 _B , 4 _B ; ‥‥‥; 3 _L , 4 _L is provided at each location, and these are shared by A / D. It is connected to the conversion circuit 30, and the digital conversion by the conversion circuit 30 allows the concrete filling status at each location to be shown as a plurality of curves on the display 32 via the computer 31 as shown in FIG. If necessary, the measured values shown in FIG. 3 can be stored in the storage means 33 such as a magnetic disk.

FIG. 5 shows an example of observing the state of concrete filling at 16 locations using the A / D conversion circuit 30 of 32 channels. In this case, the plurality of metal tubes 27a, 27b,
Is connected to 25, the calibration electrode pairs 3 _A of the measurement electrode, 4 _A; expand the arrangement of ‥‥‥ diagrammatically represents panel 34
Is shown. Symbols N-1, N in the figure are electrode pairs 3 _N-1 , 4 _N-1 ;
3 _N and 4 _N are shown. In this case, each of the electrodes 3, 4
Light emitting diode connected to each electrode with current at
15 (see FIG. 1B). Attach those light emitting diodes 15 to the corresponding electrode positions on the panel 34,
Electrode symbols corresponding to the respective light emitting diodes 15 on the panel 34 are given. According to the experiment of the present inventor, when the surface water 21 remains, the measured resistance value is about 比 compared to when the concrete is filled, and if a light-emitting diode having an appropriate voltage-luminance characteristic is used, It was confirmed that the brightness of the light emitting diode 15 on the measurement electrode 4 side when the surface water 21 remained was brighter than the brightness of the light emitting diode 15 connected to the calibration electrode 3 when the concrete was filled, so that it could be detected visually. It was confirmed that surface water detection was possible. In this case, the concrete electrode is vibrated at the position of the measuring electrode 4 corresponding to the high-brightness light emitting diode.
When the filling of 20 was promoted, it was also confirmed that the degree of filling of concrete was improved, and thus the brightness of the light emitting diode was improved.

In the above description, the metal mold 1, the calibration electrode 3 and the measurement electrode 4 each comprising a single electrical contact 5, the detection of concrete filling at the joint between the metal tank 25 and the metal pipe 27 by the light emitting diode 15, etc. However, the application of the present invention is not limited to these examples, and the wooden form 1, the calibration electrode 3 and the measurement electrode 4 with the two electrical contacts 5 and 6, the use of resistance detection means other than the light emitting diode, and the like. Is possible.

[0025]

As described above in detail, the method for detecting surface water of concrete in a formwork of the present invention detects surface water of concrete in a formwork by a change over time in resistance.
It has the following remarkable effects.

(A) Unfilled concrete in a portion of the formwork where the concrete is difficult to turn can be easily and reliably detected. (B) Since a relative value is sufficient without requiring an absolute value of the concrete resistance value, precise measurement is not required. (C) The distance between the calibration electrode and the measurement electrode can be reduced, the difference in concrete casting time between the two electrodes can be shortened, and the influence of the environment on the measured values of the two electrodes can be suppressed to a minimum level. (D) If a calibration electrode is installed at a position where high-quality concrete can be secured, filling with a vibrator or the like is promoted until the measured value at the measurement electrode matches that at the calibration electrode, thereby ensuring high-quality concrete filling over a wide range. be able to. (E) The concrete filling status at a plurality of concrete placing positions can be monitored in real time by a panel. (F) Measured values of concrete resistance during casting can be easily recorded and stored.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an illustration of a metal pipe connection to a metal tank with a concrete lining.

FIG. 3 is an electric circuit diagram for simultaneously observing unfilled concrete at a plurality of positions.

FIG. 4 is an explanatory diagram of a display device that simultaneously displays curves of a concrete filling state at a plurality of positions.

FIG. 5 is a display example of a filling state for simultaneously observing unfilled concrete at a plurality of positions.

FIG. 6 is a diagram showing a comparison between resistance values of concrete and surface water.

FIG. 7 is an explanatory view of a conventional concrete surface filling inspection method.

[Explanation of symbols]

1 concrete formwork 2 board member 2
A: Rib, 3 Calibration electrode 4 Measurement electrode
5, 5A, 6 Electrical contacts 7, 7A Insulation sheet 8 Air pocket 9
Vent hole 10 Space 12 Surface 13
Ammeter 15 Light emitting diode 17 Lead wire 20
Concrete 21 Surface water 22 Power supply 25
Metal tank 26 Concrete lining 27
Metal tube 28 Gusset plate 29 Void 30
A / D conversion circuit 31 Computer 32 Display 33
Storage means 34 Panel 35: Electrodes.

Continuation of the front page (56) References JP-A-7-26717 (JP, A) JP-A-7-26710 (JP, A) JP-A-6-229959 (JP, A) JP-A-4-349502 (JP) , A) Japanese Utility Model Showa 64-19751 (JP, U) Japanese Utility Model 7-8873 (JP, Y2) (58) Field surveyed (Int. Cl. ⁶ , DB name) E04G 21/02 103

Claims (8)

(57) [Claims] 1. A measuring electrode is mounted on a predetermined portion of an inner surface of a concrete form, and a calibration electrode is mounted on a smooth inner surface of the form below a lower portion of the concrete form. After measuring and recording the change over time of the resistance value of the concrete poured by the calibration electrode at the time of placing, the resistance value of the concrete placed by the measurement electrode at the time of placing the concrete at the predetermined site . Concrete in a mold formed by measuring a change over time and detecting surface water of concrete at the predetermined portion by relative comparison between a change over time of a resistance value at the calibration electrode and a change over time of a resistance value at the measurement electrode. Surface water detection method. 2. The surface water detecting method according to claim 1, wherein said calibration electrode and said measurement electrode are provided with a pair of electrical contacts respectively mounted on an insulating sheet and an insulating lead wire connected to each electrical contact. A method for detecting surface water of concrete in a formwork, wherein a resistance value of concrete is measured between the pair of electrical contacts of the calibration electrode or the measurement electrode using a calibration electrode or a measurement electrode. 3. The method for detecting surface water according to claim 1, wherein the calibration electrode and the measurement electrode are each provided with one electrical contact mounted on an insulating sheet and an insulating lead wire connected to each electrical contact, A counter electrode with a lead wire is provided at a position lower than the calibration electrode in the mold, and the resistance value of concrete is measured between the calibration electrode or the measurement electrode and the counter electrode by the calibration electrode or the measurement electrode. Method for detecting surface water of concrete in formwork. 4. The surface water detecting method according to claim 3, wherein said mold is made of metal, and said counter electrode is a portion below said lower portion of said metal mold. Method. 5. The surface water detecting method according to claim 2, wherein the resistance value changes with time due to a passing current between an insulated lead wire pair connected to each of a pair of electrical contacts of the calibration electrode and the measurement electrode. A method for detecting surface water of concrete in a formwork by measuring the water content. 6. The surface water detecting method according to claim 5, wherein the calibrating electrode and the measuring electrode are provided between each pair of insulated lead wires.
A method for detecting surface water of concrete in a formwork, comprising connecting a light emitting diode whose light emission amount changes according to a passing current, and measuring a change over time of the resistance value with the light emission amount. 7. The surface water detecting method according to claim 3, wherein between the insulating lead of the calibration electrode and the lead of the counter electrode and between the insulating lead of the measuring electrode and the lead of the counter electrode. , A method of detecting surface water of concrete in a formwork, comprising connecting an ammeter to each of them and measuring a change with time of the resistance value with a current flowing through the ammeter. 8. The surface water detecting method according to claim 4, wherein: between the insulating lead wire of the calibration electrode and the metal mold; and between the insulating lead wire of the measurement electrode and the metal mold.
A method for detecting surface water of concrete in a formwork, comprising connecting an ammeter and measuring a change with time of the resistance value with a current flowing through the ammeter.