JPH07108801B2 - Backfill for cathodic protection of reinforced concrete structures - Google Patents

Description

TECHNICAL FIELD The present invention relates to a backfill used for galvanic corrosion protection of a reinforced concrete structure, and more particularly, it can be manufactured in a factory and is easy to handle. The present invention relates to a backfill that simplifies the installation work of an electrocorrosion anode.

[Prior Art] In a reinforced concrete structure (hereinafter referred to as an RC structure), the pH of the concrete is generally high (12 to 13) due to the nature of cement, and a passivation film is formed on the surface of the reinforcing bar. It was thought that the corrosion of the rebar hardly occurred.
For this reason, RC has been conventionally used without taking measures to prevent corrosion of the rebar.
Although the structure was built, corrosion of the rebar occurred due to carbonization of concrete due to air pollution, chloride pollution, etc., and destruction of the passivation film of the rebar due to chloride, etc.
Leading to the destruction of structures has become a major social problem in recent years. As countermeasures, improvement of cement and concrete, anticorrosion treatment such as rust prevention treatment and coating of rebar were developed, but it is extremely difficult to apply to these existing RC structures.

Therefore, as an effective anticorrosion means for RC structures, i) zinc having an electrochemically base potential with respect to the rebar,
A galvanic anode method in which a metal such as aluminum is attached to a concrete surface as a galvanic anode and a potential difference between the metal and the reinforcing bar is used to form a battery between them to supply a corrosion-resistant current to the reinforcing bar, or ii) Currently, the main method is to use an external DC power supply, such as an external power supply method that supplies a corrosion protection current from an insoluble or sparingly soluble anode attached to the concrete surface to the reinforcing bar on the cathode side. When applying the electrocorrosion method to RC structures, it is important to reduce the contact resistance between concrete and anode and suppress the polarization of the anode in order to prevent deterioration of anode performance and long-term stabilization thereof. Is. Therefore, it is necessary to provide a layer of backfill between the concrete and the anode, which has the above effect, and the backfill is usually integrated with the anode and then attached to the RC structure together with the anode (where the concrete and anode are Which has the above-mentioned effect and is defined as a backfill, and a composition comprising bentonite, gypsum, porcelain glauber, etc., which are general components thereof, is defined as a backfill composition).

Conventionally, as the above-mentioned backfill, a powdery or particulate backfill composition kneaded with water to form a paste has been exclusively used. However, such a conventional backfill has a problem that it is difficult to carry because it takes time to package, and drying, water leakage, corrosion of surrounding materials, etc. occur during storage and transportation. Therefore, conventionally, backfill preparation and integration with the anode are performed manually at the site where the anode is attached to the RC structure. It was done in the work process of. That is, immediately before attaching the anode, first, a powdery or particulate winter backfill component is blended so as to have a desired composition, further kneaded with water to form a paste, and the obtained paste-like backfill is troweled or the like. It is a work process in which the anode is attached to the RC structure after applying it evenly to the anode surface and making the backfill side the concrete side.

[Problems to be Solved by the Invention] However, in the above-described conventional anode mounting construction method, most of the work of preparing the backfill and integrating with the anode as described above, immediately before the anode mounting, at the site, and Since it had to be done manually, the anode mounting process was extremely complicated, and there was a limit to improving work efficiency.
Further, a large amount of backfill must be prepared and the work of integrating with the anode must be performed within a limited time, which also causes nonuniformity of the backfill quality. In addition, there are many restrictions on the transportation and handling of backfill components, and the work environment is deteriorated due to the dust scattering of backfill components. Moreover, such construction sites require work such as scaffolding temporarily installed on the backside of a pier or bridge. Since there are many places where space and time constraints are severe, the conventional construction method requires a lot of labor and there is a problem in work safety.

The present invention has been made in view of the above-mentioned problems of the prior art, can be manufactured in a factory and is easy to handle, and to obtain a backfill that enables simplification of installation work of the cathodic protection anode of the RC structure. The purpose is to

[Means for Solving the Problems] As a result of earnest research aimed at achieving the object, the present inventors have found that a backfill in which a backfill composition is wrapped in a water-permeable sheet and the overall shape is a sheet is produced at a factory. It was possible and easy to handle, and it was found that the use of the backfill can greatly simplify the anode mounting work on the RC structure, and arrived at the present invention.

That is, the backfill for electrical corrosion protection of the reinforced concrete structure of the present invention is one in which the powdery or particulate backfill composition is wrapped with a water-permeable sheet and the overall shape is a sheet.

Hereinafter, the present invention will be described in more detail.

The backfill composition used in the backfill of the present invention, bentonite, gypsum, glauber and the like as a main component,
Typical examples thereof include a mixture of metal carbonate, metal phosphate, metal chloride and the like, but the mixture is not particularly limited thereto. The backfill composition to be used in the present invention may be any one as long as it has an effect of reducing the contact resistance between the anode and the concrete and suppressing the polarization of the anode, and it is usually desired that each component in the form of powder or particles is desired. It is obtained by blending so as to have a composition.

Furthermore, when a water-absorbing polymer material such as a cross-linked polyacrylic acid salt is added to the backfill composition, the water retention of the obtained backfill is increased, and the long-term stability of the anode performance tends to be further improved. preferable.

Further, the water-permeable sheet used for the backfill of the present invention is preferably one that does not reduce the effect by wrapping the above-mentioned backfill composition, and various woven fabrics, non-woven fabrics, water absorbent papers and the like can be mentioned.

Furthermore, the water-absorbent polymer material is held in the water-permeable sheet by weaving a water-absorbent polymer material in the water-permeable sheet, or by laminating a sheet made of the water-absorbent polymer material and the water-permeable sheet. Also, it is preferable because the long-term stability of the anode performance tends to be further improved.

In the backfill of the present invention, the backfill composition is wrapped with the water-permeable sheet and the entire shape is a sheet. The means include: a) means for sandwiching the backfill composition between water-permeable sheets and fractionating by quilting (the quilting process here means the upper and lower water-permeable sheets sandwiching the backfill composition, It is a process of partially (knitting, etc.) adhering by a means such as sewing so as to fractionate the fill composition) or b) a water-permeable sheet is made into a bag, and the backfill composition is filled therein. A means for juxtaposing the objects in the lateral direction and / or the longitudinal direction so that the whole shape is a sheet shape is preferable. According to the above means, a backfill can be easily produced using an automatic high-speed powder packaging machine and the backfill composition does not deviate to a part during transportation, so that the backfill composition can be favorably integrated with the anode.

The shape of the backfill of the present invention is preferably that which conforms to the shape of the anode used and can be well integrated with the anode. Examples of the anode used with the backfill of the present invention include galvanic anodes such as zinc and aluminum, and insoluble or sparingly soluble anodes such as carbon, titanium and platinum. The shape of the anode is a plate shape, a rod shape, or the like, and a plate shape is common.

Although the backfill of the present invention is described only for the electric corrosion protection of RC structures, the applicable object is not limited to the RC structures, and when the soil environment is targeted, for example, for the electric corrosion protection of the tank bottom plate. Can also be used by winding it around an insoluble anode embedded in soil in the external power supply method.

[Operation] The above-described backfill of the present invention is easy to pack and transport, does not cause a problem such as deterioration during storage and transportation, and can be easily produced by a machine such as a high-speed automatic powder packaging machine. Therefore, it is not produced at the anode mounting site as before, but is produced in advance at the factory (preparation of backfill composition,
It can be integrated with a water-permeable sheet). Further, since the backfill of the present invention is in the form of a sheet, it is easy to handle and can be integrated with the anode simply by polymerizing the anode in the factory or on site. When the backfill of the present invention is used, the main work at the site where the anode is installed is to attach the anode to the backfill integrated with the anode by RC
Immediately before mounting on the structure, water is sprinkled to absorb water sufficiently, and then it is mounted on the RC structure in the usual way.

The backfill of the present invention attached to the RC structure reduces the contact resistance between the concrete and the anode as much as or more than the conventional one, and suppresses the polarization of the anode.

[Examples] Hereinafter, the present invention will be described more specifically based on Examples.

Example 1 FIG. 1 is a partially cutaway perspective view showing a state in which a backfill according to an example of the present invention is integrated with an anode composite.

The backfill 1a in FIG. 1 is a powdered backfill composition 2a (bentonite: gypsum: magnesium chloride = 4:
1: 2 [weight ratio]) as a bag-shaped water-permeable sheet 3a and 3
It is constructed by sandwiching it between b (cotton, 500wx1000Lmm) with a thickness of 5 to 10 mm and quilting 4 (sewn) at intervals of 50 to 100 mm in length and width. On the other hand, zinc anode plate 5
(500 to 1000wx1000Lx1Tmm) is bonded to the support plate 6 (flexible board, 500 to 1000wx1000Lx6Tmm) and the double-sided adhesive rubber asphalt sheet 7 (500 to 1000wx1000Lx1Tmm) to form the anode composite 8. In FIG. 1, the backfill 1a is simply polymerized and integrated on the zinc anode plate 5 of the anode composite 8.

The backfill 1a was produced in a factory in advance using a high-speed powder automatic packaging machine (manufactured by Toyo Kikai Seisakusho), and the anode composite 8 was also produced in the factory, and each was transported to the anode mounting site. And polymerized there.

Next, the anode composite 8 integrated with the backfill 1a was attached to the RC structure (the back side of the floor slab of the port cargo shelving pier) with the backfill 1a on the concrete side by a usual method.

At that time, at the site where the anode is installed, it is only necessary to sprinkle water on the backfill 1a immediately before installing the anode, the work time for installing the anode is shortened to about 1/10 of the conventional one, and the backfill composition does not have dust, and there is no excess bag. The fall of Phil into the sea has also been resolved. Further, the backfill 1a of the present embodiment reduces the contact resistance between the anode and the concrete and suppresses the polarization of the anode like the conventional backfill, and the RC structure is stable for a long period of time. It was galvanically protected.

Further, the backfill composition 2a in the backfill 1a was not biased during transportation from the factory to the site, and the backfill 1a and the anode composite 8 could be favorably attached to the RC structure.

Embodiment 2 FIG. 2 is a partially cutaway perspective view showing a state in which a backfill according to another embodiment of the present invention is integrated with an anode composite.

In FIG. 2, a powdery backfill composition 2b similar to that of Example 1 was filled in an elongated bag 9 (30φ × 500 Lmm) made of a water-permeable sheet 3c (cotton), and the same as that of Example 26 of Example 26. By arranging them side by side in the lateral direction on the same anode composite body 8, a backfill 1b having an overall shape of a sheet is formed, and the backfill 1b is integrated with the anode composite body 8.

The process of filling the bag 9 with the backfill composition 2b is performed in advance using a high-speed powder automatic packaging machine (manufactured by Toyo Kikai Seisakusho), and the anode composite 8 is also produced in the factory. , Each of them is transported to the anode mounting site and the bag 9 is juxtaposed on the anode composite 8, that is, the backfill 1b.
Was integrated with the anode composite 8. In addition, the bags 9 may be connected in parallel in advance and integrated into a sheet shape before being integrated.

The anode composite 8 integrated with the backfill 1b was attached to the RC structure (the backside of the deck of the port cargo shelving pier) in the same manner as in Example 1, and the anode attachment at that time was the same as in Example 1. It was easy, the working environment was not deteriorated, and the anode performance after mounting was the same.

Examples 3 and 4 Water-absorbent polymer material (vinyl alcohol-acrylate copolymer, trade name: Sumikagel S-50, Sumitomo Chemical Co., Ltd.)
1 to 2 with respect to 100 parts by weight of the backfill composition.
Parts by weight except that it was added to the backfill composition (Example 3), or 40 parts by weight to 100 parts by weight of the water-permeable sheet was held in the water-permeable sheet by quilting (Example 4). A backfill was prepared in the same manner as in Example 1, integrated with the anode composite, and subjected to galvanic protection of the RC structure (the back side of the floor slab of the port loading shelf type pier).

The backfills of Examples 3 and 4 had higher water retention than the backfill of Example 1, and both of them improved the long-term stability of anode performance further than Example 1. In addition, the effects of the present invention such as simplification of anode attachment work were obtained in the same manner as in Example 1.

[Effects of the Invention] As described above, the backfill of the present invention does not require the work of compounding the backfill composition, kneading with water, coating on the anode, etc. at the anode mounting site as in the conventional case. It can be produced in advance in the factory, is easy to handle, and is very easy to integrate into the anode. for that reason,
By using the backfill of the present invention, the work at the site where the anode is mounted is greatly reduced compared with the conventional one, the mounting work of the anode for cathodic protection of the reinforced concrete structure is extremely simplified, and the deterioration of the working environment is prevented. As a result, work efficiency can be improved, labor is significantly reduced, and work safety is also improved.

Further, since the backfill of the present invention can be manufactured in a factory, a homogeneous product can be efficiently obtained, and in addition, standardization of the backfill and mechanization of a series of production lines are easy.

Furthermore, when the backfill of the present invention is used, an anode performance equal to or higher than that of a conventional one can be obtained, and particularly in the backfill of the present invention, a water-absorbing polymer material is added to the backfill composition or water permeability is increased. It can be held on a sheet to further improve the long-term stability of the anode performance.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a state in which a backfill according to one embodiment of the present invention is integrated with an anode composite, and FIG. 2 shows a backfill according to another embodiment of the present invention. FIG. 3 is a partially cutaway perspective view showing a state of being integrated with an anode composite. 1a, 1b: backfill, 2a, 2b: backfill composition, 3
a, 3b, 3c: Water-permeable sheet, 4: Quilting processing (seams), 5: Zinc anode plate, 6: Support plate, 7: Double-sided adhesive rubber asphalt sheet, 8: Anode composite, 9: Bag.

Claims (6)

[Claims] 1. A backfill for electrical corrosion protection of a reinforced concrete structure, wherein the powdery or particulate backfill composition is wrapped with a water-permeable sheet and the overall shape is a sheet. 2. The backfill according to claim 1, wherein the backfill composition is sandwiched between the water-permeable sheets and fractionated by a quilting process. 3. A bag made of the water-permeable sheet is filled with the backfill composition, and the bags are juxtaposed in a lateral direction and / or a longitudinal direction so that the entire shape is a sheet. The backfill described in 1. 4. The backfill according to claim 1, wherein the water-permeable sheet is one of a woven cloth, a non-woven cloth and a water absorbent paper. 5. The backfill according to claim 1, wherein a water-absorbent polymer material is added to the backfill composition. 6. The backfill according to claim 1, wherein the water-permeable sheet holds a water-absorbent polymer material.