JP2002090323A - Method for examining charge behavior in concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine properties including the degradation of a concrete, in a non-destructive state. SOLUTION: Primary voltage V1 is applied to a concrete lump 1 through an insulating polymeric sheet 3 to determine the charge behavior in the concrete lump 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This onset name BACKGROUND OF THE INVENTION The deterioration prediction of concrete, degradation properties, related to research methods to accurately grasp by <br/> behavior of the charge of the physical properties in the concrete.

[0002]

2. Description of the Related Art Conventionally, there is a non-destructive inspection method using an electric method as a means for predicting deterioration of concrete and examining changes in deterioration properties and physical properties. This is a method in which the electrical resistance value is first determined as an applied voltage / steady flow, and the resistivity of the concrete (resistance value × electrode area / sample thickness) is calculated from the electrical resistance value. It is said that it is largely dependent on the rate, salt content, and the like, and has been used as an effective and simple means for examining the properties of concrete.

Therefore, as a confirmation of the conventional example, as shown in FIG. 7, conductive rubber electrodes 2 and 2 are provided on the upper and lower opposing surfaces of a commercial concrete lump 1 each having a length, width and thickness of 30 cm square. A power supply E was connected in between, a primary voltage V ₁ (step voltage) of 10 to 100 mV was applied, and the relationship of the current flowing through the concrete lump 1 was examined.

[0004] As a result, the current i immediately after applying the primary voltages V ₁ as shown in FIG. 8 will be momentarily somewhat s decreases as shown in FIG. 9, it was found that thereafter maintaining a steady state. As described above, a steady flow i is generated while a constant voltage is applied to the concrete lump 1, which simply indicates the resistance value of the concrete lump 1, and this value corresponds to the area and thickness of the electrode 2. The resistivity is calculated by multiplying the reciprocal.

There is also a measuring method for examining the permeability of chloride ions by applying a DC power supply to a concrete using an aqueous solution of sodium chloride. However, the resistance value in this case is easily affected by a chemical change due to the aqueous sodium chloride solution, and there is a question about the reliability of the measurement result.

[0006]

However, in the above-mentioned conventional method, the magnitude of the current flowing in the concrete is simply measured by an externally applied voltage. (Behavior) could not be measured, and therefore it was not easy to accurately investigate the properties of concrete or predict deterioration. The present invention aims to solve the above-mentioned problems of the prior art.

[0007]

Means for Solving the Problems An insulator is interposed between concrete and a power supply to prevent a current from an applied power supply from flowing into the concrete, and a voltage is applied to the concrete to move only internal charges. The behavior of electric charge indicating the properties of concrete is grasped from the relationship between voltage and current at that time.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to embodiments shown in the drawings. It has been conventionally thought that the degree of deterioration of concrete is related to electric resistance, but it is not sufficient by itself. I could not say. Therefore, the present invention describes a means that can grasp a state in which only internal charges move (behave) without applying charge injection from a power supply by spatially applying a voltage to concrete.

[0009] As shown in FIG.
Conductive rubber electrodes 2 and 2 are provided on the upper and lower opposing surfaces of a commercial concrete lump having a width and a thickness of 30 cm each, and the resistance of the concrete lump is larger than the resistance of the concrete lump on the conductive rubber electrodes 2 and 2. The same conductive rubber electrodes 4 and 4 as the above-described conductive rubber electrodes 2 and 2 are laid outside the insulating polymer sheets 3 and 3 (made of polyethylene) with a thickness of 0.1 mm.

As described above, the power supply E is connected to the outer conductive rubber electrodes 4 and 4 so that
By applying a primary voltage V ₁ (step voltage) having a high V, a secondary voltage V ₂ as shown in FIG. 3 acts on the concrete lump 1 through the polymer sheets 3, 3.
₂ is initially a few tens of mV, after which the voltage gradually decreases towards zero.

[0011] In this case the current i flowing through the concrete mass 1 becomes the concrete mass 1 to the voltage V ₂ decreases sharply in between t ₁ ~t ₂ and early that acts zero state as in FIG. 4, After that, while the remaining voltage is applied, t _{2 to} t ₃
In this case, a negative current flows, and the backflow disappears almost at the same time when the residual voltage becomes zero.

This means that the concrete mass 1 and the applied power source E
Since maintaining high insulating state by interposing a polymer sheet 3,3, be applied to the primary voltages V ₁ in this state, it charges from the power source E is injected into the concrete mass 1 between the In other words, it is considered that only the electric charges in the material constituting the concrete block 1 were promoted to move, and the current i as shown in FIG. 4 was generated.

[0013] In other words, between the secondary voltage _{V 2} Initial _t 1 ~t
If ₂ is moved positive charge e of the inner concrete in the direction of normal negative electrode (forward) by the secondary voltage V ₂ as shown in FIG. 5, the residual voltage becomes weak, the t ₂ ~t ₃ It is considered that the positive charge e during the movement caused a diffusion phenomenon in a reflective manner, and most of the positive charge e caused a backflow in the direction of the positive electrode as shown in FIG.

[0014] concrete mass 1 and concrete mass without charge injection from the power source E by in a state between the electrically cut off the power supply E to apply the voltages V ₁ to the concrete mass 1 as described above 1 A current (backflow) occurs due to the behavior of the electric charge in the inside.

As described above, the time integral value of the absolute value of the negative current (backflow) (integration of the current waveform in the negative portion) is an index indicating the property of the transition zone in the concrete. This is considered to indicate that the amount of ions increases and that the ion is likely to be deteriorated or that the deterioration is progressing.

That is, the movement of the electric charge in the concrete is related to the development of the transition zone. In the concrete in which the transition zone is developed, the electric charge is likely to move, and the deterioration is considered to be caused by the movement of the ions in the concrete. It is considered that the deterioration is likely to occur when the transition zone develops.

Generally speaking, the physical properties of concrete are not uniform because they vary depending on the composition such as moisture and salt content, but this current (backflow) is the basic pattern that characterizes the properties of the transition zone in concrete. It is a guide to concrete deterioration prediction, deterioration properties and physical properties. It is a clue.

[0018] While the application of the primary voltages V ₁ as step voltage in the present invention, the characteristics of the negative current as described above can be obtained even DC or AC voltage. However, when an AC power supply is used, it is considered that ions having a low moving speed (kind of element) have a negative current in a power supply having a low frequency, and ions having a fast moving speed have a negative current in a power supply having a high frequency. As a result, it is thought to be useful for classification of ions (kinds of elements) related to corrosivity, and the properties of the transition zone can be analyzed in more detail as compared with the case where the step voltage is applied.

[0019]

According to the present invention, by electrically interrupting the connection between the power supply and the concrete and applying a voltage from the outside, the movement of only the electric charge in the concrete can be detected without charge injection from the power supply, and the transition zone in the concrete can be detected. It is possible to judge the properties of concrete including the deterioration from the behavior of the electric charge indicating the properties of the concrete.

In the above-mentioned conventional example, since the electrode is made of copper-copper sulfate, the electrolytic solution permeates into the concrete layer and the resistance cannot be measured accurately. However, in the present invention, the electrode is formed by using a conductive rubber for the electrode. The addition does not affect the resistance value of the concrete itself at all, and since it uses conductive rubber as an electrode, the electrical contact state with the concrete is stable, and the reliability of the measurement results can be significantly increased. It is very easy.

In particular, determination can be easily made by numerical analysis without using a large-scale device.

By controlling the applied voltage according to the situation at the site, the physical properties of the concrete can be easily observed in a non-destructive state.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for implementing the present invention.

FIG. 2 is a diagram illustrating a primary voltage applied to an insulating polymer sheet according to the method of the present invention.

FIG. 3 is a diagram of a secondary voltage characteristic acting on concrete by the method of the present invention.

FIG. 4 is a characteristic diagram of a current flowing in concrete by the method of the present invention.

FIG. 5 is an explanatory diagram of a current generated by a secondary voltage acting on concrete.

FIG. 6 is an explanatory diagram of a current generated at a later stage of a secondary voltage acting on concrete.

FIG. 7 is a schematic view showing a method of implementing a conventional example.

FIG. 8 is a step voltage diagram applied to the electrodes in FIG. 7;

FIG. 9 is a characteristic diagram of the current flowing in the concrete in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Concrete mass 2, 4 Conductive rubber electrode 3 Polymer sheet A Ammeter E Power supply V Voltmeter i Current flowing by power supply E V ₁ Primary voltage applied to polymer sheet V ₂ Secondary voltage acting on concrete mass

Claims (4)

[Claims] 1. A method for investigating a charge behavior in concrete, wherein a voltage is applied to the concrete via an insulator. 2. The method according to claim 1, wherein the applied voltage is a step voltage. 3. The method according to claim 1, wherein the applied voltage is a DC voltage. 4. The method according to claim 1, wherein the applied voltage is an AC voltage.