JPH0393681A - Desalting of rc, src structure - Google Patents

Abstract

PURPOSE:To eliminate chipping operation and to discharge chloride ion in concrete out of system in a short time by bringing a solution of electrolyte into contact with the surface of concrete structure and carrying out electrolyte using a reinforcing material in the structure as a cathode. CONSTITUTION:Desalted part of concrete structure 10 is covered with a container 20 of bottomed structure and the container 20 is charged with a solution of electrolyte 30. An electrode 40 is set in the solution of electrolyte 30, made into an anode, reinforcing materials 11 such as reinforcing bar or steel frame of the concrete structure 10 are used as cathodes, several volt - tens volt electric voltage is applied from a DC electric source 50 to the electrodes, an electric current is sent and chloride ion existing in the structure 10 is attracted to the anode 40 to remove salt content.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a technology for preventing salt damage in reinforced concrete (RC) and steel frame concrete (SRC) structures, and more specifically, the present invention relates to technology for preventing salt damage in reinforced concrete (RC) and steel frame concrete (SRC) structures. The present invention relates to a method for desalting an RC-SRC structure.

BACKGROUND OF THE INVENTION It is generally known that concrete structures using sea sand and concrete structures in coastal areas crack and peel.

This is due to the expansion pressure when the salt in the concrete rusts the reinforcing bars and steel frames inside the structure.

Conventionally, there are the following two methods for repairing concrete structures that are likely to rust or have rusted.

One method is to remove the concrete from the rusted area and then backfill it with salt-free concrete.

Another method is cathodic protection, which suppresses the battery action that causes rust on reinforcing bars and steel frames by applying electricity to concrete structures, and is expected to be put into practical use in the future.

This cathodic protection method involves forming a conductive coating layer on the stripped rusted whistle, installing a highly corrosion-resistant anode rod on the surface of this coating layer, and using the internal reinforcing bars or steel frame as a cathode. This is a method of energizing a free current power source so that a potential of 100 mV or more becomes base.

<Problems to be Solved by the Present Invention> The conventional rust prevention technology for concrete structures described above has the following problems.

<B> In the former method, there remains a possibility that the flying salt particles will penetrate into the concrete structure and cause rust to occur again, forcing repeated repair work.

Moreover, there is a problem in that repairing concrete structures requires a lot of effort and time.

<mouth> In the case of the latter method, electricity must be permanently energized.

Furthermore, since the electrical resistance of concrete changes due to changes in moisture content and temperature, it is difficult to adjust the amount of current.

Moreover, since the anode rod inevitably wears out, a new anode rod including the conductive coating layer must be replaced periodically.

〈C〉 Since both have chisels, they cannot be used for a long period of time during the work period due to structural (strength) problems on road bridges, bridges, etc.

<Objective of the present invention> The present invention was made in order to solve the above problems, and its purpose is to eliminate the need for chisel work, to desalinate in a short period of time, and furthermore to An object of the present invention is to provide a method for desalting an RC-SRC structure, which allows reuse of the RC-SRC structure.

<Means for Solving the Problems> That is, the present invention provides a bottomed Tachibana container on the surface of a concrete structure, fills the container with an electrolyte solution, arranges an electrode in the electrolyte solution, and uses this as an anode. At the same time, the cathode is connected to the conductive reinforcing material in the concrete structure, and DC power is applied between both electrodes to remove chlorine ions in the concrete from the system. Desalination of RC-SRC structures It's a method.

<Description of the present invention> The present invention will be described below with reference to the drawings.

<A> Principle of desalination FIG. 1 shows a longitudinal cross-sectional view of a concrete structure 10 such as a bridge pier that is likely to rust or has rusted.

As shown in the figure, the present invention surrounds the desalination area of a concrete structure 10 with a container 20 having a bottomed structure, and fills the container 20 with an electrolyte solution 30.

The electrode 40 set in the electrolyte solution 30 is used as an anode, and the conductive reinforcing material 11 such as a reinforcing bar or steel frame of the concrete structure 10 is used as a cathode, and electricity is supplied from a DC power source 50.

When electricity is applied between the electrode 40 and the reinforcing material 11, chlorine ions present in the concrete structure 10 are attracted to the electrode 40 and dissolved in the electrolyte solution 30.

As a result, salt in the concrete structure 10 is removed.

Next, each of the above-mentioned members will be explained.

Exit> Container The purpose of the container 20 is to store the electrolyte solution 30, and the material thereof is not limited to wood, steel, resin, etc.

The shape of the container 20 is similar to that of the concrete structure 1 to be desalinated.
Determined by 0 target, dragon salt range, etc.

<C> Electrolyte solution As the electrolyte solution 30, tap water or a known solution in which electrolyte substances (various salts and alkaline substances) are dissolved to improve conductivity can be used.

<2> Electrode For the electrode 40, a metal or conductive material with a small ionization tendency is used.

The electrode 40 is an electrode used in the external power supply method for cathodic protection, such as carbon, graphite, magnetic iron oxide, silicon cast iron, lead alloy, platinum, etc., or a material made of these materials adhered to a conductive resin plate. can use things.

The electrode 40 may be used by being fixed to the inner surface of the container 30 in advance, or may be used separately from the container 30.

〉Applied voltage The voltage applied between the electrode 40 and the reinforcing material 11 varies depending on the scale of desalination, but is set in a relatively low range of several volts to several tens of volts.

It is true that the desalination effect can be promoted by increasing the applied voltage, but on the other hand, the amount of hydrogen generated at the reinforcing material 11@, which is the cathode, increases, which may induce hydrogen magic in iron or cause workers to Since there is also the problem of deterioration of the environment, it is necessary to be careful in setting the applied voltage.

Note that this problem of hydrogen embrittlement does not occur with materials other than high-tensile steel and prestressed steel.

<Test Example> Next, the following test was conducted to confirm the desalting effect of the present invention.

Kui〉Concerning the desalination effect of applied voltage and electrodes A concrete specimen (with 20c+axlOc+mXlO) was made using sea sand with a high salt content and one reinforcing bar was buried in the center, and one side of it (103×20 After sealing the other side while leaving the
at. The amount of desalination (in terms of Nacl) over time was measured using Ca(OR)2) as an electrolyte and changing the load voltage and anode. :X, hr), and the coefficient of X was taken as the desalination rate (Nacl gr/hr).

Figure 2 shows the test results of the relationship between load voltage and desalination rate.
Figure 3 shows the test results on the relationship between the type of anode and the desalination rate, and Figure 4 shows the test results on the relationship between the area ratio (@pole area/mortar/concrete area) and the desalination rate.

<Effects of the Present Invention> Since the present invention is as described above, the following effects can be obtained.

<B> Since desalination can be carried out without making any changes to the concrete structure, there is no need for the conventional chisel work.

〈口〉 Since it can desalinate with high efficiency, the construction period can be shortened.

<C> Even if an expensive platinum-based electrode is used as the anode, it can be removed and reused after desalination work is completed, so it is highly versatile.

(2) When targeting road and railway bridges, desalination can be carried out while vehicles are still running.

<E> It can be applied to desalination of a wide range of concrete structures, such as various underwater/offshore concrete structures, concrete structures near beaches, or concrete structures using sea sand.

[Brief explanation of drawings]

Figure 1 2 Conceptual diagram of the desalination method according to the present invention Figure 2: Explanation of test results on the relationship between load voltage and desalination rate Figure 3: Explanation of test results on the relationship between anode type and desalination rate Figure 4: Explanation of the test results of the relationship between area ratio (anode area/mortar/concrete area) and desalination rate. Kakuhaya me j 2 y Jcl tsutsumi i otsu kal 7um @ ice ■ fi me (
8 Ptlκ (2r) Ko f't me. 6 PLiq~ (zp) C5pL) Anode mirror frequency removal 4 Liao

Claims (1)

[Claims] (1) A container with a bottomed structure is provided on the surface of the concrete structure, the container is filled with an electrolyte solution, an electrode is placed in the electrolyte solution to serve as an anode, and the conductivity in the concrete structure is reinforced. A cathode is connected to the concrete, and a DC power is applied between both electrodes to remove chlorine ions in the concrete from the system.
Method for desalting SRC structures.