KR101135613B1 - Manufacturing method of light-weight grounding rod - Google Patents

Abstract

PURPOSE: A method for manufacturing a light weighted conductive ground rod is provided to offer a light weighted ground rod with an excellent strength and grounding at the same time, thereby enhancing the work efficiency. CONSTITUTION: A light weighted aggregate is sprayed or dipped with a CNT dispersion conductive hydrosol solution. The light weighted aggregate is formed with a conductive coating light weighted aggregate having the coating thickness of 5um or more and the surface resistance of 1,000Ω / sq or less. A conductive concrete is mixed to the conductive coating light weighted aggregate. An iron subsidiary material is coated with the conductive concrete. The iron subsidiary material is formed into a rod shape. A conductive silane coupling rust preventive is sprayed on the iron subsidiary material.

Description

Manufacturing Method of Lightweight Conductive Grounding Rod {Manufacturing Method of Light-Weight Grounding Rod}

The present invention relates to a method for manufacturing a lightweight conductive ground rod, and more particularly, to a method of manufacturing a ground rod that can secure strength and grounding properties as well as corrosion prevention characteristics of iron and steel materials, and light weight than conventional conductive ground rods. It is about.

Electrical and electronic devices require a grounding system to prevent damage to the equipment due to high voltage currents caused by fault currents and lightning strikes. The grounding system has a form in which a grounding member is buried underground and connected to an electronic device to discharge it. In general, the grounding member is connected between the grounding members in the form of a plate or rod using conductive concrete and ferrous materials. This is made to facilitate.

The grounding member is manufactured by forming a form in which iron parts are embedded using conductive concrete mixed with cement, an inorganic filler, a reaction regulator, and conductive carbon fibers. 1 is an example of a ground rod manufactured in the form of a rod, in which a ground connecting rod is disposed therein and a connection screw is formed at both ends of the ground connecting rod, and an adapter is connected to the connection screw so that another ground rod to a ground plate may be connected. .

However, the conventional grounding rods made of conductive concrete have excellent discharge effects, but have been pointed out that they are heavy. If the ground rod is heavy, it is not easy to connect several ground rods, so the construction period is easy to be delayed. In order to improve the above problems, the use of lightweight aggregate can be considered. However, lightweight aggregates have high absorbency, which increases the amount of water mixed in the concrete mixing process, so that the strength characteristics of the final concrete hardened body are easily degraded. As a result, conventional lightweight aggregates have not been used in manufacturing ground rods.

In addition, the conventional ground rods are easily embedded with iron sub-materials to corrode over time to cause expansion cracks, and corrosion of the iron sub-materials leads to problems of dropping of conductive concrete and increase of electrical resistance. Accordingly, in order to prevent corrosion of the iron parts, the anti-corrosive agent is directly applied to the iron parts before forming the ground rod to give corrosion resistance to the iron parts or the anti-rust agent is applied to the surface of the ground rod after the ground rod is formed to provide water repellent properties to the micropores of the concrete surface. It was intended to prevent moisture particles from penetrating the concrete. However, due to the deterioration of adhesion between the iron and the conductive concrete due to the rust preventive agent, the physical performance of the ground rod is decreased, or the electrical resistance between the conductive concrete and the iron subsidiary material increases by applying a low conductivity anticorrosive agent to the iron and the anticorrosive agent. The coating method has not been applied because of the problem of corrosion of the exposed iron subsidiary materials when cracking or breakage occurs on the concrete surface of the applied ground rod.

The present invention has been developed to improve the problem of heavy weight of the conventional ground rod and the corrosion problem of the iron sub-material embedded in the ground rod, has the following technical problems.

First, it is to provide a method for manufacturing a new conductive grounding rod that can reduce the weight and excellent strength characteristics and grounding characteristics with the existing grounding rod.

Second, to provide a manufacturing method of the ground rod that can effectively suppress the corrosion of the iron sub-materials, such as the ground connecting rod built in the ground rod.

Third, it is desirable to use artificial lightweight aggregate using industrial by-products to reduce the manufacturing cost of ground rods and to pursue environmental friendliness by recycling industrial by-products.

In order to solve the above technical problem, the present invention, the conductive concrete is mixed with a light weight aggregate prepared by applying or immersing a lightweight aggregate in a conductive hydrosol solution, and the iron submaterial coated with a conductive silane-bonding rust preventive agent is applied to the conductive concrete. The present invention provides a method for manufacturing a lightweight conductive grounding rod, characterized in that the coating is solidified to form a rod.

The conductive coating lightweight aggregate is an artificial lightweight aggregate manufactured by bottom ash, sewage sludge sludge, cold rolled hot sludge, stone powder, clay, etc., and has a degree of polymerization of 500 to 2,000 in the molecular structure of (CH ₂ CHOH) n and a solid content of 15 to 25. It is preferable to apply | coat or immerse with CNT dispersion conductive hydrosol solution which is%, and what was manufactured with the coating thickness of 5 micrometers or more and surface resistance of 1,000 Pa / sq or less. In addition, conductive concrete is usually 25 to 70% by weight of Portland cement, 5 to 9% by weight of inorganic filler, 5 to 9% by weight of fine aggregate, 15 to 33% by weight of conductive coating lightweight aggregate coated with conductive hydrosol solution, Powder comprising 0.1 to 4.2% by weight of conductive carbon fiber, 4.2 to 12.0% by weight of reaction modifier, 0.3 to 6.0% by weight of steel fiber, and 0.4 to 1.8% by weight of one or more additives of a dispersant and a fluidizing agent; It is preferable to mix | blend with 30-45 weight% of water with respect to the said powder.

In addition, the conductive silane-bonding rust inhibitor for applying to iron subsidiary materials is hexamethyldisilazane, N-2aminoethyl3-aminopropyltrimethoxysilane (N-2 (aminoethyl) 3-amonipropyltrimethoxysilane), 3-amino One or more silanes selected from 3-aminopropyltriethoxysilane were mixed with 5-30% hydrolysis in water by weight, followed by acetic acid solution containing 0.5-5% solids and 20-60 nm copper colloid dispersed. It is preferable to use the one prepared so that the pH is 6.5 ~ 7.5. On the other hand, it is preferable to apply | coat an electroconductive silane anticorrosive agent to an iron submaterial so that it may have a coating thickness of 10 micrometers or more and surface resistance of 2,000 kPa / sq or less.

First, as a result of using the conductive coating lightweight aggregate when compounding the conductive concrete in the production of ground rods, it is possible to advantageously manufacture a lightweight ground rod that can satisfy both the desired strength characteristics and grounding characteristics. This makes it possible to reduce the weight of the ground rod, leading to improved workability and reduced construction costs due to shortening of air in related construction.

Second, since the conductive silane coupling rust inhibitor is applied to the iron sub-materials in the manufacture of the ground rods, it is effective to prevent the corrosion of the iron sub-materials and to maintain the adhesion between the iron sub-materials and the conductive concrete, and to produce a ground rod having excellent conductivity at the contact surface of the iron sub-materials and the conductive concrete. As a result, it is possible to provide a grounding rod in which electrical characteristics are effectively maintained. In particular, it is possible to solve the problem of deterioration of the electrical properties of the ground rod due to the deterioration of the adhesion between the iron subsidiary material and the conductive concrete and low electrical properties, which is a problem when applying the rust preventive agent.

Third, since the artificial light weight aggregate made of industrial by-products can be advantageously used, it is possible to improve economics and environment-friendly through high value-added industrial by-products.

1 is a photograph of a conventional ground rod.
Figure 2 is a schematic diagram of the conductive coating lightweight aggregate preferably used in the present invention.
Figure 3 is a schematic diagram of a state in which a conductive silane coupling rust inhibitor is applied to the iron subsidiary material in the manufacturing process of the ground rod according to the present invention.
Figure 4 is a plan cross-sectional view of the ground rod preferably proposed in the present invention

The present invention is characterized by the use of conductive coating lightweight aggregate as aggregate in the conductive concrete formulation for the manufacture of ground rods. Here, the conductive coating lightweight aggregate is formed by coating or immersing the lightweight aggregate in a conductive hydrosol solution to form a coating film on the surface of the lightweight aggregate, as shown in FIG. 2, preferably bottom ash, sewage sludge, cold rolled hot sludge, stone powder, Artificial lightweight aggregates made of clay are coated or immersed in a (CH ₂ CHOH) n molecular structure with a CNT dispersed conductive hydrosol solution having a polymerization degree of 500 to 2,000 and a solid content of 15 to 25%. It is manufactured at 1,000 mW / sq or less. Such conductive coating lightweight aggregate can be advantageously used in the production of ground rods because the water absorption is controlled by the coating film and the conductivity is provided, and in particular, the mixing amount of the carbon fibers used for conductivity in the mixing of the conductive concrete for manufacturing the ground rods Can be reduced.

In addition, the present invention is characterized in that the iron subsidiary materials (ground connecting rod, connecting screw, etc.) embedded in the ground rod is coated with a conductive silane coupling rust inhibitor as shown in FIG. It is applied to the conductive silane-bonded rust preventive agent with excellent adhesion and conductivity to maintain the excellent electrical properties and adhesion between the iron subsidiary materials and the conductive concrete as well as preventing corrosion of the iron subsidiary materials.

As described above, the present invention mixes the conductive concrete with the conductive coated lightweight aggregate prepared by applying or dipping the light weight aggregate with the conductive hydrosol solution, and solidifies the iron subsidiary material coated with the conductive silane coupling rust inhibitor with the conductive concrete to form a rod-type ground rod. As a result of the molding production, it is possible to secure not only the strength characteristics and the grounding characteristics of the conventional ground rods, but also the anti-corrosion characteristics of the iron subsidiary materials and the light weight.

Meanwhile, the present invention proposes a grounding rod 10 as shown in FIG. 4 in the form of a preferred grounding rod. 4 is a cross-sectional plan view of the ground rod, in which the ground connecting rod 12 is embedded in the concrete body 11 and is horizontally embedded with the connecting screw 13 mounted at both ends thereof. The connection screw 13 may be connected to an electric device by using an adapter or the like, and other ground rods or ground plates may be connected in series and in parallel.

In addition, the present invention proposes a combination of the preferred conductive concrete for the production of ground rods. Usually 25 ~ 70% by weight of Portland cement, 5 ~ 9% by weight of inorganic filler, 5 ~ 9% by weight of fine aggregate, 15 ~ 33% by weight of conductive coating lightweight aggregate coated with conductive hydrosol solution, and conductive carbon fiber 0.1 ~. Powder comprising 4.2 wt%, reaction modifier 4.2-12.0 wt%, steel fiber 0.3-6.0 wt%, 0.4-1.8 wt% of one or more additives of a dispersant and a glidant; 30 to 45% by weight of water with respect to the powder; will be included. The powder can be prepared by mixing in advance with the premix.

Portland cement is usually a binder and is used at 25 to 70% by weight. If it is less than 25% by weight, it is difficult to express sufficient strength of the cured product, and if it exceeds 70% by weight, it is difficult to secure fluidity due to excessive viscosity and there is a concern of cracking problem.

Inorganic fillers are used to improve the strength and watertightness of cements by exerting a filling effect on the voids in cement, and it is appropriate to use 5 to 9% by weight in powder to realize this purpose effectively. As an inorganic filler, calcium carbonate is preferable.

Fine aggregate is used for strength improvement, and silica sand is suitable. Fine aggregates are used in the powder 5 ~ 9% by weight, respectively, if less than 5% by weight of the strength enhancement effect is insignificant, if more than 9% by weight excessive use of the cured body is feared to increase the weight.

Conductive coating lightweight aggregate will be used to replace the amount of conventional inorganic filler and fine aggregate to ensure conductivity and lightness. The conductive coating lightweight aggregate is prepared by coating or dipping with a conductive hydrosol solution to control the water absorbency of the lightweight aggregate and impart conductivity. That is, the lightweight aggregate in the conductive concrete mixing process to prevent the absorption of the mixing water by the conductive hydrosol solution coating film on the surface to minimize the amount of the mixing water used. In addition, since the conductive coating lightweight aggregate is cured while the conductive hydrosol solution film is gradually dissolved in the curing step of the conductive concrete to form a polymer structure, it contributes to the improvement of physical performance of the ground rod hardened body. Furthermore, since the conductive material (CNT, etc.) is dispersed in the conductive hydrosol solution, the conductive material will be present in the conductive concrete as the conductive hydrosol solution is dissolved, thereby exhibiting excellent electrical properties. Such a coating lightweight aggregate is used in the powder 15 to 33% by weight, less than 15% by weight is not a large contribution to the weight reduction, 33% by weight is difficult to meet the physical performance required by the ground rod.

On the other hand, it is suitable to use lightweight aggregate having the characteristics as shown in the following [Table 1] for the production of conductive coating lightweight aggregate, and in particular, one or more materials of bottom ash, sewage sludge, cold rolled hot sludge, stone powder, and clay are mixed through a predetermined process. It is preferable to use the manufactured artificial lightweight aggregate.

[Table 1] Characteristics of lightweight aggregate

In addition, it is preferable to use a CNT dispersed conductive hydrosol solution having a degree of polymerization of 500 to 2,000 and a solid content of 15 to 25% in the (CH ₂ CHOH) n molecular structure as the conductive hydrosol solution for the production of conductive coating lightweight aggregate. This conductive hydrosol solution is a mixture of (CH ₂ CHOH) n molecular structure polymer powder having a degree of polymerization of 500 ~ 2,000 in water and heated to 35 ~ 40 ℃ CNT solution having a solid content of 1.5 ~ 5%, other additives ( What is necessary is just to add and disperse a dispersing agent, a fluidizing agent, etc.). If the degree of polymerization of the polymer powder is less than 500, the bonding strength between the polymer structures is weak and easily dissolved by water, so that the coating film of the light weight aggregate is likely to peel off during the water mixing process of the conductive concrete. If so, the dissolution characteristics are too low, which does not contribute to the improvement of the physical performance of the cured product. In addition, CNT solution is suitable if the diameter-length ratio of 10 ³ ~ 10 ⁴ and the dispersion of CNT with an electrical conductivity of 5,700 ± 200 S / ㎝.

The conductive coating lightweight aggregate may be manufactured by coating or dipping the lightweight aggregate (particularly artificial lightweight aggregate) as described above by applying or immersing the conductive hydrosol solution, and the conductive coating lightweight aggregate has a coating thickness (coating thickness) of 5 μm or more. It is preferable to produce the surface resistance of 1000 Pa / sq or less to express the expected effect as the conductive coating lightweight aggregate.

In conductive concrete, the conductive carbon fiber is used to improve the electrical conductivity as well as to enhance the strength, preferably 0.1 to 4.2% by weight in the powder. If the conductive carbon fiber is less than 0.1% by weight, the electrical resistivity is high due to the deterioration of the electrical properties of the conductive concrete, and if it exceeds 4.2% by weight, the conductivity tends to be irregular due to the entanglement of the carbon fibers when the conductive concrete is mixed. It is preferable that the conductive carbon fiber has a length of 1 to 15 mm as the PAN system, but if it is less than 1 mm, the electrical resistance increases, and if it exceeds 15 mm, the dispersion property is lowered due to the entanglement between the carbon fibers, thereby increasing the electrical resistance or partly more electrical. The lower the resistance, the more likely the current flows in reverse.

Reaction modifiers are used to stimulate the hydration of cement to improve the curing properties. Calcium sulfo aluminate (CSA) is preferred. When the reaction modifier is used in the powder 4.2 ~ 12.0% by weight, if less than 4.2% by weight of the addition effect is insignificant, if it exceeds 12.0% by weight excessive use is feared to decrease the physical performance.

Steel fiber (steel fiber) is used for the purpose of strength enhancement and electrical conductivity, like conductive carbon material, 0.3 ~ 6.0% by weight in powder. Steel fiber is preferably END HOOK TYPE or BUNDLE TYPE with a length of 30 ~ 50㎜. If the length is less than 30mm, the electrical resistance is high and the ground resistance effect is reduced. If the thickness exceeds 50mm, the dispersibility is reduced due to entanglement between steel fibers. There is a high possibility that the problem of high electrical resistance is partially caused.

On the other hand, ground rods may be inferior in the manufacturing process if too many steel fibers or carbon fibers due to the shape of the rod, so it is desirable to reduce the amount of steel fibers or carbon fibers as much as possible. Due to the short distance between the connecting rod and the outside, it is not a big problem for the electrical conductivity.

The additive is used at least one of a dispersing agent or a fluidizing agent to improve the mixing dispersibility and fluidity between the components, wherein the dispersing agent is an anionic surfactant, the fluidizing agent is suitable to adopt a melamine type. The additive is used in the powder 0.5 to 1.5% by weight, less than 0.5% by weight does not have an effect on the sufficient dispersibility or fluidity exertion, and more than 1.5% by weight may be uneconomical and cause material separation.

After the powder is composed of the materials as described above, 30 to 45% by weight of water is added to the powder to form a conductive concrete for manufacturing a ground rod. At this time, when the blended water is less than 30% by weight of the powder, it is difficult to secure workability due to lack of fluidity, and when it exceeds 45% by weight of the powder, the lack of strength of the concrete may be feared.

In addition, the present invention proposes to apply a conductive silane-bonded rust preventive agent to the iron submaterials before coating and forming the iron submaterials with conductive concrete in manufacturing the ground rod. This is to prevent corrosion of the iron subsidiary materials. In particular, the conductive silane bond rust preventive agent is hexamethyldisilazane, N-2 aminoethyl 3-aminopropyltrimethoxysilane (N-2 (aminoethyl) 3-amonipropyltrimethoxysilane), 3-aminopropyltriethoxysilane ( 3-aminopropyltriethoxysilane) mixed with 5-30% hydrolysis of one or more selected silanes in water by weight ratio, and then added with an acetic acid solution containing 0.5-5% solids and a copper colloid having a particle size of 20-60 nm. It is preferable to make it to ˜7.5, which is a result in consideration of securing adhesion and rust prevention effect. The conductive silane-bonded rust preventive prepared in this way is suitable to be applied to the iron submaterial to have a coating thickness of 10 μm or more and a surface resistance of 2,000 μs / sq or less. It is advantageous to maintain the properties.

Hereinafter, look at the physical characteristics of the conductive ground rod according to the present invention based on the embodiment. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[ Example Property test

1. Conductive Coating Lightweight Aggregate  Produce

Using the artificial lightweight aggregate and the conductive hydrosol solution of the characteristics shown in Table 2 below to prepare a conductive coating lightweight aggregate. The artificial lightweight aggregate was coated and dried with a conductive hydrosol solution to prepare a conductive coated lightweight aggregate having a coating thickness of 20 μm and a surface resistance of 920 μs / sq.

[Table 2] Materials for the manufacture of conductive coating lightweight aggregate

2. Specimen Fabrication

Conductive concrete was blended with 36 wt% water of powder and powder according to [Table 1] below, and a conductive concrete and a conductive ground rod were manufactured according to RS standard.

[Table 3] Powder Composition of Conductive Concrete for Ground Rods

3. Test result

The conductive concrete specimens and ground rods were evaluated for properties in accordance with KEPCO registration standard RS-5975-0067 after 7 days of curing in each case. In particular, to evaluate the change in electrical resistivity of the specimen and the ground rod, the specimen and ground rod, which were cured for 7 days, were placed under constant temperature and humidity conditions (20 ± 1 ℃, 90%) for 28 days. To evaluate the corrosion characteristics, ground rods were immersed in a solution with a salt concentration of 50 ± 5 g / L for 60 days, and then the ground rods were cut longitudinally to check the degree of corrosion on the contact surface of the conductive concrete and the iron subsidiary materials and to indicate the corrosion area compared to the contact surface. Evaluated as. The results are shown in the following [Table 4] and [Table 5].

[Table 4] Characteristics of conductive concrete specimen

[Table 5] Grounding rod characteristics

As shown above, in the case of conductive concrete specimens, the electrical resistivity of both Example 1 using the conductive coated lightweight aggregate with fine aggregate, Comparative Example 1 using only fine aggregate, and Comparative Example 2 using untreated artificial lightweight aggregate and fine aggregate were calculated by KEPCO. It was confirmed that it satisfies 0.1 mm or less specified in RS-5975-0067. However, it was confirmed that the electrical resistivity of Example 1 was considerably lower than that of Comparative Examples 1 and 2, because the CNT having conductivity was dispersed in the concrete micropores as the coating film of the conductive coating lightweight aggregate was dissolved due to water absorption. do. In addition, the electrical resistivity of Comparative Example 2 is lower than that of Comparative Example 1, and the moisture absorbed by the untreated lightweight aggregate remains after curing, which is considered to result in lower electrical resistivity.

The compressive strength and the flexural strength of the conductive concrete specimens were higher in Example 1 than in Comparative Example 1, which is considered to increase in strength as the conductive hydrosol solution film dissolved in the ground rod molding curing step was filled in the micropores of the conductive concrete. In Comparative Example 2, the compressive strength and the flexural strength were found to be greatly decreased, which was increased due to the water absorption of the untreated lightweight aggregate during the compounding process, and thus, the compressive strength and the flexural strength were deteriorated. In the case of unit volume weight, it can be seen that the lowest in Example 1, from which it can be seen that the weight can be reduced according to the present invention.

On the other hand, in the case of the ground rod, as a result of measuring the electrical resistance change rate, it was confirmed that both Comparative Examples 1 and 2 and Example 1 did not exceed 5% specified in the KEPCO registration specification RS-5975-0067. However, the electrical resistance change rate of Example 1 is lower than that of Comparative Examples 1 and 2, which maintains the electrical properties between the conductive concrete and the iron subsidiary material because the conductive silane-coated coating coated for the light weight aggregate and the antirust property has excellent conductivity. Seems to be.

In addition, the comparison of the corrosion degree of the comparative examples 1 and 2 using the untreated anticorrosive iron subsidiary material in the manufacture of ground rods and the example 1 using the iron subsidiary material coated with the conductive silane-bonded rust preventive agent, the conductive concrete and iron in the case of Comparative Examples 1 and 2 Although many corrosion could be confirmed at the contact surface of the auxiliary material, it was confirmed that the corrosion did not appear in Example 1. As a result, anticorrosive properties of the iron subsidiary materials can be expected through the application of the conductive silane bond rust inhibitor.

According to the above results, if the coated light aggregate and the silane-bonded copper colloidal rust preventive agent having conductivity are appropriately applied to the ground rod manufacture, the ground rod can be made lighter according to the weight loss per unit volume, and the anti-corrosive effect of the iron subsidiary material and the conductivity of the rust preventive agent can be obtained. It can bring about the effect of lowering the electrical resistance change rate, and the improvement of the physical performance by the water absorption characteristics, which can be a problem when applying untreated lightweight aggregate, will be improved to ensure sufficient physical performance.

10: ground rod
11: concrete body
12: grounding rod
13: Connection thread

Claims (5)

Lightweight aggregates are coated or immersed in a (CH ₂ CHOH) n molecular structure with a CNT dispersed conductive hydrosol solution with a polymerization degree of 500 to 2,000 and a solid content of 15 to 25% .The coating thickness is 5 µm or more and surface resistance is 1,000Ω / sq or less. Manufactured by conductive coating lightweight aggregate,
Conductive concrete is blended with the conductive coating lightweight aggregate,
A method for manufacturing a lightweight conductive grounding rod, comprising: forming an iron sub-material coated with a conductive silane-bonding rust inhibitor with the conductive concrete to form a rod. In claim 1,
Lightweight aggregate for the production of the conductive coating lightweight aggregate,
A method of manufacturing a lightweight conductive ground rod, characterized in that the artificial lightweight aggregate manufactured by at least one of bottom ash, sewage sludge, cold rolled hot sludge, stone powder, clay. In claim 2,
The conductive concrete,
Usually 25 ~ 70% by weight of Portland cement, 5 ~ 9% by weight of inorganic filler, 5 ~ 9% by weight of fine aggregate, 15 ~ 33% by weight of conductive coating lightweight aggregate coated with conductive hydrosol solution, and conductive carbon fiber 0.1 ~. Powder comprising 4.2 wt%, reaction modifier 4.2-12.0 wt%, steel fiber 0.3-6.0 wt%, 0.4-1.8 wt% of at least one additive of dispersant and fluidizing agent; and
30 to 45% by weight of water with respect to the powder; manufacturing method of lightweight conductive ground rod, characterized in that the formulation. 4. The method according to any one of claims 1 to 3,
The conductive silane bond rust inhibitor,
Hexamethyldisilazane, N-2 aminoethyl3-aminopropyltrimethoxysilane (N-2 (aminoethyl) 3-amonipropyltrimethoxysilane), 3-aminopropyltriethoxysilane (3-aminopropyltriethoxysilane) The above silane was prepared by mixing 5 ~ 30% hydrolysis in water by weight ratio, and then adding acetic acid solution containing 0.5 ~ 5% solids and 20 ~ 60nm of copper colloid in dispersion to pH 6.5 ~ 7.5. Method for manufacturing a lightweight conductive ground rod characterized in that. delete

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