JPH0330849Y2 - - Google Patents

Description

[Detailed description of the invention] <<Industrial application>> This invention is a corrosion monitoring device for reinforcing bars that easily determines whether the reinforcing bars in reinforced concrete are in a state of corrosion due to concrete neutralization or the action of chlorides. Regarding.

[Conventional technology] Conventionally, concrete is partially destroyed to expose the internal reinforcing steel. The state and degree of corrosion of the reinforcing bars was determined by visually observing these exposed locations.

Alternatively, it was used to inspect concrete cores extracted from walls or slabs.

In any case, such a determination method involves a large amount of labor and subsequent repair work, such as the work of extracting the concrete core and the work of sagging the concrete.

In addition, we were constrained by the number of inspection locations and the number of inspections, which had a negative impact on the strength of the structure.

When determining the degree of corrosion, it is unclear whether rust has formed before the reinforcing bars are embedded in concrete, and conversely, even if there is no rust on the reinforcing bars, there is no possibility that the reinforcing bars will corrode. In some cases, there were unavoidable concerns that the decision could be made incorrectly.

[Problem that the invention aims to solve] Originally, the steel in concrete is placed in the strong alkaline atmosphere that the concrete maintains, so its oxidation-reduction action is stopped.

However, carbon dioxide gas and some acidic substances in the atmosphere act on the concrete, and over many years the concrete loses its alkalinity, and the steel gradually begins to corrode. In addition to this, if water-soluble chlorides are contained in concrete at a density above a certain level, corrosion will be induced even in an alkaline atmosphere.

Recently, it has become clear that marine aggregates that have not been sufficiently desalinated and sea salt particles carried by the sea breeze dissolve in rainwater and accumulate in concrete, causing corrosion of concrete reinforcing bars. .

In the situation described above, there is a need for a method that can easily investigate and diagnose the corrosion state of steel in concrete.

The present invention was developed in view of the above circumstances, and its purpose is to provide a reinforcing steel corrosion monitoring device that can easily and quickly determine the state of reinforcing steel corrosion and its progress rate without destroying the concrete of a structure. It is on offer.

<Means for Solving the Problems> In order to achieve the above object, the reinforcing steel corrosion monitoring device according to the present invention includes a probe made of the same kind of metal and a different kind of metal as the reinforcing bars electrically insulated with an insulating material, The probe is previously buried in the concrete structure to be monitored, and an ammeter is connected in series between the similar metal and the dissimilar metal.

<<Effect>> A difference in free energy occurs between parts of concrete where the reinforcing steel is corroded and parts where it is not.
Force-wise, this releases energy to stabilize the system. This work becomes an electromotive force, and the corroded part becomes an anode and causes an oxidation reaction, and the other part becomes a cathode and causes a reduction reaction. In other words, a state that can be called a corrosion battery is formed,
Corrosion progresses with corrosion current.

A closed circuit is formed in which a dissimilar electrode with a large difference in natural electrode potential relative to the reinforcing steel is used as a cathode or anode, and the metal serving as the cathode (anode) is used as a standard electrode. Therefore, it goes without saying that depending on the metal material used as the standard electrode, this may become a cathode or an anode.

The condition of the reinforcing bars is determined by the amount and direction of current indicated by the ammeter.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a probe 1 used in the present invention.
Any metal such as titanium (Ti), copper (Cu), platinum (Pt), etc. may be used, but in this case, the dissimilar metal 3 made of copper is used as an insulating material 4 such as epoxy resin or Bakelite.
It is integrally constructed into a rod shape with the two sides in between.

The probe 1 shown in FIG.
A lead wire 5-5 is connected to each end of the dissimilar metal 3.

The probe 1' shown in FIG. 1B has a dissimilar metal 3-3 attached to both ends of a steel material 2 via an insulating material 4-4, and a lead wire 5-5 is connected to the steel material 2. There is one in which dissimilar metals 3-3 are short-circuited. By doing so, the internal resistance of the dissimilar metal 3-3 is lowered, and the reliability of the probe 1 itself is improved.

In the probe 1, the iron material 2 and the dissimilar metal 3 may not be arranged in a straight line, but may be arranged in parallel depending on the shape and situation of the buried part of the concrete structure, and the gap between them may be interrupted by an insulating material 4. In short, it is sufficient that the iron material 2 and the dissimilar metal 3 are electrically insulated.

As shown in FIG. 2, the probe 1 is buried in concrete 6 constituting the structure during concrete pouring. And lead wire 5 is concrete 6
The ammeter 7 is connected to this. The ammeter 7 only needs to be able to measure currents from 0.1 μA to about 100 μA.

In this way, when the alkali concentration of the concrete 6 becomes neutral, the iron material 2 of the probe 1 is activated and forms a local battery. At that time, a corrosion current using the dissimilar metal 3 as a reference electrode passes through the ammeter 7, and the amount of discharge of the iron material 2 is known. By doing so, it is possible to infer the condition of reinforcing bars arranged in the concrete 6 and to know the degree of corrosion progress.

<<Effects>> As explained in detail above, according to the reinforcing steel corrosion monitoring device according to the present invention, metals of the same kind as the reinforcing bars and metals of different kinds are insulated from each other and buried in concrete. Since these are connected via an ammeter, changes in the electrode potential of the same type of steel as the reinforcing steel can be continuously monitored against the natural electrode potential held by dissimilar metals, and the effects of concrete quality, external environment, and cover thickness can be monitored continuously. The various factors involved in the corrosion of reinforcing bars can be monitored and grasped under actual conditions. Furthermore, there is no need to remove concrete at all, and the corrosion status of reinforcing bars can be determined simply and quickly.

[Brief explanation of drawings]

FIGS. 1a and 1b are side views illustrating the probe used in the present invention, and FIG. 2 is an explanatory diagram showing the state of the probe and ammeter buried in concrete. 1...Probe, 2...Iron material, 3...Different metal, 4...Insulating material 7...Ammeter.

Claims (1)

[Scope of utility model registration request] A probe is constructed of the same kind of metal and a different kind of metal as the reinforcing bars electrically insulated with an insulating material, and the probe is buried in advance in the concrete structure to be monitored, and
A corrosion monitoring device for reinforcing bars, characterized in that an ammeter is connected in series between the similar metal and the dissimilar metal.