JP3291286B2 - Conductive cement composition and conductive cured product produced from the composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive cement composition and a conductive cured product produced from the composition. More specifically, the present invention relates to a conductive cured product having good conductivity. The present invention relates to a conductive cement composition having excellent adhesion to soil, which can minimize contact resistance with soil while maintaining a low resistance value, and a conductive hardened body produced from the composition.

[0002]

2. Description of the Related Art Generally, when a voltage higher than a voltage generated from an electrical equipment due to a lightning strike or a fault current due to a ground fault or the like flows into the electrical equipment, a potential rise occurs in and around the electrical equipment. May occur. Grounding is usually performed in order to effectively suppress such a rise in the earth potential, take appropriate measures such as protecting the electric circuit of the fault current, and protect the human body and facilities.

[0003] Grounding is to electrically connect the ground and electrical equipment, but requires a substantially low resistance value. The ground resistance is composed of three types of components: a soil resistance around the ground electrode, a conductor resistance of the ground electrode, and a contact resistance between the surface of the ground electrode and the soil.

[0004] The soil resistance around the ground electrode depends to a large extent on the soil conditions at the site, but chemical reducing agents have been developed and used to reduce soil resistance.

However, the effect of the chemical reducing agent is temporary because it flows into rainwater and groundwater after the construction, and its constituents are discharged into the soil to pollute the surrounding environment. The fact is that the amount of use is gradually decreasing.

As another method for lowering the grounding resistance, a cement-based reducing agent has been developed and used. This method is to enlarge the grounding electrode to lower the resistance. The technical focus of the cement-based reducer is mainly on lowering the conductor resistance of the ground electrode itself, and therefore the cement-based reducer has its limitations.

When actually looking at the components of grounding, the resistivity of the soil is the largest factor, but this is difficult to artificially control, and it is more difficult than the conductor resistance of the grounding electrode itself.
It is known that the contact resistance between the ground electrode and the soil has a greater effect on the ground resistance.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve all of the above problems, and an object of the present invention is to combine materials having excellent adhesion to soil. An object of the present invention is to provide a conductive cement composition which is used as a material and has excellent adhesiveness to soil, which minimizes the contact resistance with soil and obtains a low resistance value while maintaining good conductivity of the electrode itself. .

Another object of the present invention is to mix the conductive cement composition and a filler material and harden them by hydration.
An object of the present invention is to provide a manufactured conductive cured body.

[0010]

In order to achieve the above-mentioned object, the conductive cement composition of the present invention comprises a calcium sulfo-aluminate (calcium sulpho-aluminate).
aluminate, also referred to as CSA) 10 to 40% by weight of clinker powder mainly composed of minerals, portland cement
ment) 1 to 30% by weight, quicklime or slaked lime 10
40% by weight, 5-30% by weight of anhydrous gypsum, silicate 0.1
100% by weight of soil binder composed of ~ 2.0% by weight
And 0.1 to 2 parts by weight of a mixed material and 0.5 to 2 parts by weight of carbon fiber with respect to 100 parts by weight of a soil binder. Further, in order to uniformly disperse the carbon fibers and enhance the physical properties of the cured product, the conductive cement composition further includes 5 to 30 parts by weight of aggregate with respect to 100 parts by weight of soil binder. It is desirable.

Further, according to another aspect of the present invention, there is provided a cured conductive material characterized by mixing the above-mentioned conductive cement composition with a filler and curing the mixture by hydration to produce the cured product. You. The filler is made of soil, silica fume, metakaolin, fly ash (f)
It is preferred to be selected from one or more of the group consisting of lyash), slag and stone powder.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the conductive cement composition according to the present invention and a conductive cured product produced from the composition will be described more specifically.

The conductive cement composition according to the present embodiment is mainly composed of a soil binder, carbon fiber, and a mixture.

First, a binder used for binding to soil is constituted by adding portland cement, lime, gypsum and a reaction accelerator to a quick-setting clinker mainly composed of a calcium sulfoaluminate mineral. You.

[0015] In order to solve the above-mentioned problems, the conductive cement composition according to the present embodiment comprises clinker powder 10 containing a calcium sulfoaluminate-based mineral as a main component.
40% by weight, Portland cement 1-30% by weight, quicklime or slaked lime 10-40% by weight, anhydrous gypsum 5-30
1% by weight, and 0.1 to 2.0% by weight of silicofluoride.

In this embodiment, the calcium sulfoaluminate mineral is 3CaO.3Al ₂ O ₃ .Ca
SO ₄ component a clinker a containing more than 50 wt%, in order to have a fast-curing, ettringite (Etringi by reacting with Portland cement, quick lime or slaked lime and anhydrite during hydration
te) or monosulfate (monosulfat)
forming e). This hydrate has a large number of bonds, has high strength properties, and is produced even in the presence of an organic substance, and thus is suitable for the use and purpose of the present invention. The particle size of the powder is 3,000 to 6,000 cm ^{2 in the} Blaine specific surface area.
/ G is possible, and 4,000 ± 500 cm ² / g is the best. The Blaine specific surface area of a calcium sulfoaluminate mineral affects the initial reaction rate, and the higher the specific surface area, the faster the reaction rate.

The anhydrous gypsum according to the present embodiment has a lower dissolution rate than hemihydrate gypsum and muddy gypsum, so that it is compatible with the reactivity with calcium sulfoaluminate-based mineral, and has high strength and solidified. Contributes to the safety of soil bodies. Since anhydrous gypsum reacts with calcium sulfoaluminate-based mineral, quicklime or slaked lime to form ettringite, its amount is determined by the amount of calcium sulfoaluminate-based mineral, quicklime or slaked lime. The weight ratio of nate-based mineral / anhydrite is 1 or more and 3 or less, and most preferably 2.5 ± 0.1. This ratio of calcium sulfoaluminate mineral / anhydrite affects long-term stability (water control stability) and durability, and greatly assists in developing high strength. The natural anhydrous gypsum used in the present embodiment is II
It is a type of anhydrous gypsum, and the particle size of the powder is 3,000 to 8,000 cm ² / g in Blaine specific surface area.

The use of quick lime or slaked lime not only generates hydrates by the pozzolanic reaction and contributes to strength development, but also quick lime reacts at an early stage to generate heat and form calcium hydroxide. This is because it reduces the water content of the soil, secures initial strength, and contributes to preventing cracking due to drying shrinkage. Therefore, in this embodiment, it is more advantageous to use quicklime than slaked lime.

Silica fluoride is calcium sulfoaluminate.
Accelerates the hydration reaction with
At the same time as silica (S
iO ₂), Alumina (Al₂O₃)
By accelerating the pozzolanic reaction,
It is possible. As a result, high strength properties can be obtained especially from the beginning
Obtainable. In this embodiment, the silicon fluoride
Is K₂SiF₆, MgSiF₆, NaSiF₆use
But then K₂SiF₆The effect is the best.

The characteristic reaction of the soil additive of the present embodiment will be described as follows.

First, a large amount of ettringite is produced. Since ettringite has a large amount of water as the number of bonds, it reduces the water ratio and restricts the movement of soil factors.
Make it possible to combine. In the binder according to the present embodiment, the hydration rate of such ettringite was promoted by adding a silicon fluoride salt.

Second, the addition of silicofluoride not only promotes the production of ettringite, but also speeds up the pozzolanic reaction with the soil, enabling rapid hardening and high strength.

Third, the initial large amount of calcium ions discharged from cement, quicklime or slaked lime causes the soil particles to aggregate.

As the carbon fiber, a PAN-based carbon fiber is used, and a carbon fiber having a length of 3 to 20 mm or less is suitable for use. The amount of carbon fiber used is preferably 0.5 to 2 parts by weight based on 100 parts by weight of the soil binder.

The mixed material is used for ensuring the work during molding by mixing the material with water, but lignin-based, naphthalene-based and melamine-based materials can be used. It is preferable to use 0.1 to 2 parts by weight based on 100 parts by weight of the soil binder.

In the conductive cement composition according to the present embodiment, it is preferable to use an aggregate to uniformly disperse the carbon fibers and to enhance the physical properties of the cured product, and it is also possible to use silica sand. Yes, it is possible to use amorphous graphite, artificial graphite and coke powder. The amount of aggregate used at this time is preferably 5 to 30 parts by weight based on 100 parts by weight of the soil binder.

On the other hand, a filler is mixed with the conductive cement composition as described above, and the mixture is hardened by hydration.
A conductive cured body used for the ground electrode is actually manufactured.

As the filler, it is possible to use on-site soil which can be said to be an advantage of the present embodiment. The soil is preferably a coarse-grained soil series, and among them, a sandy soil and a cohesive sandy soil series are particularly preferred. Such soil is a soil that can be easily collected from the surroundings, and it is preferable to use the soil binder of the present embodiment in an amount of 3 to 200% by weight based on the soil. If the content is less than 20% by weight, it is difficult to develop a predetermined strength, and if it exceeds 200% by weight, the strength increases but is not economically advantageous.

It is also possible to use inorganic fine powder such as silica fume, metakaolin, fly ash, slag and stone powder as a filler instead of soil at the site.

[0030]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the scope of the present invention.

[0031]

[Table 1]

(1) Production of the cured product The production of the cured product for measuring the physical properties of the cured product according to the present embodiment is described in JIS R 5201 “Physical Testing Method of Cement”.
by. According to the above mixing ratio, the composition according to the present example and water were mixed using a mortar mixer, and 4 cm wide × 4 cm long
An m × 16 cm long mold was fully filled. Then, it is cultivated in a thermo-hygrostat at a temperature of 20 ± 1 ° C. and a relative humidity of 90% or more. The cured product that had been trained for 24 hours was removed from the mold and measured for physical properties.

(2) Measurement of Physical Properties of Cured Body In order to measure the electrical resistivity of the cured body, the removed cured body was left in the air for about one hour, and then silver electrodes (silver paste) were applied to both ends of the cured body. ), And then measure the resistance using a resistance measuring instrument. The measured resistance value is used to calculate the resistivity according to the following equation. Electric resistivity ρ (Ω · m) = resistance R (Ω) × cross-sectional area (m ² ) / length (m)

The strength is measured by culturing the demolded cured body for 6 days, and then measuring the bending strength and the compressive strength.
The bending strength was measured according to R5201 “Physical test method for cement”, and the compressive strength was measured using the cut specimen.

(3) Ground Resistance Test A ground resistance test was performed to test the effect of the conductive composition of the present invention on the reduction of the ground resistance due to the adhesion to the soil. To perform the test, the ground resistivity was measured using a four-point measuring instrument, and the ground resistivity was analyzed to be 180 Ω · m.

Then, each one has a width of 0.4 m, a depth of 1 m, and a length.
Excavation of 3m, BC100mm ²Fix the wires below
After laying, mix 10kg of material per 1m with water
And rebuilt with soil.

The grounding resistance measuring instrument is a BID of a four-point measuring instrument.
DET2 / 2 manufactured by DLE was used, and the measuring method was a potential drop method (Fall of potential Metho).
The measurement was performed in d).

[0038]

[Table 2]

Although the preferred embodiments and examples of the present invention have been described above, the present invention is not limited to such examples. It is obvious for those skilled in the art that various changes or modifications can be made within the scope of the technical idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

[0040]

As can be seen from the above description, according to the present invention, by using a material having excellent adhesion to the soil, the conductivity and mechanical strength of the electrode itself can be maintained well while the soil is maintained. This has the effect of minimizing the contact resistance with the wire and obtaining a low resistance value.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C04B 22:06 C04B 22:06 Z 22:12 22:12 22:14) 22:14) B 111: 94 111: 94 (56 References JP-A-4-74747 (JP, A) JP-A-55-23053 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 28/02 C04B 14/38 C04B 22/12 C04B 22/14 C04B 111: 94

Claims (4)

(57) [Claims] 1-10% by weight of clinker powder containing calcium sulfoaluminate mineral as a main component, 1-30% by weight of Portland cement, quicklime or slaked lime
Soil binder 100 composed of 0 to 40% by weight, 5 to 30% by weight of anhydrous gypsum, and 0.1 to 2.0% by weight of silicofluoride
Wt. And 100 parts by weight of soil binder, 0.
A conductive cement composition comprising 1 to 2 parts by weight and 0.5 to 2 parts by weight of carbon fiber. 2. 5 parts by weight of said soil binder is 100 parts by weight.
The conductive cement composition of claim 1, further comprising up to 30 parts by weight of aggregate. 3. A conductive cured product, which is produced by mixing the conductive cement composition according to claim 1 and a filler, and curing the mixture by hydration. 4. The method of claim 3, wherein the filler is selected from one or more of the group consisting of on-site soil, silica fume, metakaolin, fly ash, slag, and stone powder. Conductive cured body.