JP3185980B2 - Building electromagnetic shielding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic shielding method for a building.
More particularly, the present invention relates to an electromagnetic shielding method for a building using electromagnetic shielding mortar and concrete as a material or interior material of a wall surface or a floor slab of a building where electromagnetic shielding is required.

[0002]

2. Description of the Related Art In an office building or the like, a wireless LAN system (Local Area Network) using microwaves or millimeter waves is used.
rk System), indoor PHS (Personal Handy Phone Syst)
With the spread of em), requirements for electromagnetic shielding between the inside and outside of a building or between sections inside a building (hereinafter sometimes referred to as electromagnetic shielding of a building) are increasing.

For example, in a wireless LAN system or an indoor PHS, electromagnetic shielding of a building is required from the viewpoint of preventing leakage of communication information. When using PHS indoors,
In order to compensate for interference between different floors and lack of channels, electromagnetic shielding of buildings is required.

[0004] Further, in a facility in a building such as a concert hall, it is sometimes required to shield communication radio waves so as not to disturb the ringing sound of the portable telephone. Also, in broadcast facilities and medical facilities in buildings equipped with electronic devices that are easily affected by radio waves, it is necessary to provide electromagnetic shielding for broadcast radio waves and mobile phone radio waves in order to keep the electric field strength in the facilities below the level of resistance of the equipment. Is done. The electromagnetic shielding is not limited to microwaves and millimeter waves, but is also required for VHF bands and UHF bands of television radio waves and the like.

[0005] One example of the conventional electromagnetic shielding method for a building is a conductive member such as a metal plate, a metal foil, a metal net, or a composite member thereof, which can provide a required radio wave attenuation level to an outer wall, a slab, a partition wall or the like of the building. (Hereinafter referred to as an electromagnetic shielding member) to shield the inside of the building from the outside.

[0006]

However, the conventional method of covering the wall of a building with an electromagnetic shielding member requires that the electromagnetic shielding member be covered after the building of the building is cast. Since it takes time and effort, there is a problem that the entire construction period becomes long. Further, when it is necessary to cover the wall with a plurality of electromagnetic shielding members, radio waves are likely to enter from the joint of the members, and there is also a problem that the shielding leakage of the radio waves causes deterioration of the shielding performance.

Therefore, an object of the present invention is to perform construction in a short time.
Another object of the present invention is to provide an electromagnetic shielding method for a building, which can reduce the shielding leakage of radio waves .

[0008]

Referring to the embodiment of Figure 1 and 2 SUMMARY OF THE INVENTION The electromagnetic shielding method of building of the present invention, cement 5
50 to 300% by weight of metallic Fe, Al, Mg powder 3 and / or
Alternatively, an electromagnetic shield obtained by kneading oxide powders 4 of these metals.
50 to 500% by weight of mortar or cement 5
Electromagnetic mixture of metal powder and / or metal oxide powder
Shielding target of a wall of specified thickness d made of shielding concrete
The transmission coefficient T with respect to radio waves of a frequency is measured, and the measured transmission coefficient T and the predetermined thickness d are calculated into a relational expression (see the following equation (2)) between the wall thickness d, the transmission coefficient T, and the dielectric constant ε. To obtain the dielectric constant ε of the mortar or concrete, and the thickness d of a wall and / or a slab that gives a desired shielding performance against radio waves of the shielding target frequency is expressed by the dielectric constant ε in the relational expression. calculated by the assignment, in which the mortar or concrete by forming a wall and / or slabs shielding buildings by pouring a thickness d which is the calculated.

In general, mortar is a mixture of fine aggregate such as sand, cement and water. (Architectural Term Dictionary Editorial Board "Architectural Term Dictionary (Second Edition)" (1995-4-10) In the present invention, the metal powder 3 and / or the metal oxide powder 4 can be used as fine aggregate in the present invention. Preferably, the electromagnetic shielding mortar 1 is obtained by kneading 30 to 70% by weight of water 6 with respect to the cement 5. However, if necessary, the electromagnetic shielding mortar 1 used in the present invention may be kneaded with fine aggregate 7 such as sand in an amount sufficient to improve the flexibility at 100% by weight or less based on the cement.

[0010] Preferably, by mixing the coarse aggregate 7 into the electromagnetic shielding mortar 1 used in the present invention, metal Fe, Al,
The electromagnetic shielding concrete 2 in which the Mg powder 3 and / or the oxide powder 4 of these metals are kneaded can be obtained. In this case, 50 to 500% by weight of metal powder based on cement 5
The electromagnetic shielding concrete 2 can be obtained by kneading the body 3 and / or the metal oxide powder 4 with 30 to 500% by weight of fine aggregate and coarse aggregate 7 and 30 to 70% by weight of water 6. .

The metal powder 3 and / or the metal oxide powder 4
For example, dust generated in the iron making process (hereinafter, sometimes referred to as iron making dust ) can be used. Steelmaking dust is environmental dust that is collected by a dry or wet dust collector from dust and dust generated from each worksite of a steelworks.The characteristics and properties of components differ depending on the facility where the dust is generated, and are unique to each facility. There is a name. However, the electromagnetic shielding mortar 1 and the concrete 2 of the present invention are not limited to the use of iron-making dust , and other appropriate metal powder 3 and / or metal oxide powder 4 can be used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Metal powder 3 and / or metal oxide powder
Body 4 (hereinafter, collectively they may be referred to metallic powder.) Using a blast furnace dust collected is a type of steel dust as shielding performance of electromagnetic shielding mortar 1 used in the present invention (electromagnetic wave attenuation amount) An experiment to confirm was performed. An example of the composition of the blast furnace dust collected in the experiment was 40% by weight of Fe.
₂ O ₃ , 5 wt% FeO, 0.5 wt% SiO ₂ , 0.4 wt% Al
_It contained ₂ O ₃ and 0.6% by weight of MgO. Blast furnace dust is provided in the gutters and openings from the tap hole to the gutter tip and the outlet to prevent smoke and dust generation associated with tapping and slag discharge work, and to improve the atmosphere of hot work. Dust collected via a duct from the cover and hood, and air curtains installed at the main places of dust and smoke emission between them.

In this experiment, as shown in FIG.
Metal powders 3 and 4 made of blast furnace dust, ordinary Portland cement 5 and water 6 are kneaded at a weight ratio of 1: 1: 0.5 in the same manner as ordinary mortar to form an electromagnetic shielding mortar 1. As shown in FIG. 1 (C), a panel material 16 having a thickness d = 30 mm was manufactured from the mortar 1, and the shielding performance was confirmed using the panel material 16 after 50 days had passed since the casting. Further, for comparison, a panel material 16 was manufactured by using ordinary mortar (hereinafter referred to as comparative mortar) in which sand, ordinary Portland cement 5 and water 6 were kneaded at a weight ratio of 1: 1: 0.5, and the shielding performance was also improved. confirmed.

[0014] However electromagnetic shielding mortar 1 to be used in the present invention
Is generally not limited to the use of Portland cement, but may use other suitable cements. In the present invention, only blast furnace dust is used as fine aggregate, and other fine aggregate such as sand may not be kneaded. However, in order to adjust the softness of the mortar, 100% by weight or less based on cement is used. Other fine aggregates may be kneaded in an amount sufficient to improve flexibility. Practically, a soft mortar in which 30 to 50% by weight of other fine aggregate is kneaded with cement is preferable.

The reason why the panel material 16 used 50 days after the casting was used is that the permeability coefficient T of the mortar sharply increases for about one month after the casting and the shielding performance is not stable. During this period, the hydration reaction in the mortar 1 progresses greatly,
The decrease in the water content in the mortar 1 is considered to be the main cause of the increase in the permeability coefficient. The present inventor has experimentally confirmed that the permeability coefficient T is greatly reduced by increasing the water content of the mortar.

As a device for measuring the shielding performance of the panel material 16,
As shown in FIG. 4, a vector network analyzer (VNA) 24, a radio transmitter 25 and a receiver (horn antenna) 26 were used. The transmitter 25 and the receiver 26 are arranged in shielded rooms 20a and 20b separated by the partition wall 22 so as to be opposed to predetermined positions of the partition wall 22, respectively.Electromagnetic shielding mortar or comparative mortar is provided in a hole provided at a predetermined position of the partition wall 22. Panel material
The panel 16 was fitted, and the panel member 16 and the partition wall 22 were fixed in close contact with each other so as to prevent radio waves from leaking. Shield room 20a, 2
By covering the inner surface of Ob and both surfaces of the partition wall 22 with a radio wave absorbing member, it is possible to prevent a radio wave entering from the outside or a radio wave reflected on the inner surface of the shield room from being received by the receiver 26.

[0017] Using the 800MHz~4.2GHz band as a radio frequency, and transmits the radio wave to be perpendicular to the plane of the panel member 16 from the transmitter 25, receiving radio waves transmitted through the panel material 16 at the receiver 26 Then, the amplitude of the transmitted radio wave was measured by the analyzer 24. Further, the panel member 16 is removed from the hole of the partition wall 22, and the amplitude of the radio wave received through the gap of the hole is measured.
The shielding performance (electromagnetic wave attenuation) of the panel material 16 was determined from the ratio to the amplitude of the transmitted radio wave. The experimental results are shown as a graph in FIG. Since the relationship between the shielding performance and the transmission coefficient T can be expressed by the following equation (1), the transmission coefficient T of the panel member 16 can be calculated based on the value of the shielding performance.

[0018]

[Equation 1] Shielding performance = -20 · log (transmission coefficient T) ………………………… (1)

As can be seen from the graph of blast furnace dust collected in FIG . 5, blast furnace dust collected kneading mortar 1 having a thickness of 30 mm.
About 20dB at 1GHz, about 27dB at 2GHz,
Approximately 35dB shielding performance was obtained at 3GHz. Further, as can be seen from a comparison between the graph of the comparative mortar and the graph of the blast furnace dust collection dust in FIG. 5, the panel material 16 of the blast furnace dust collection dust kneading mortar 1 is compared with the panel material 16 of the comparative mortar,
A shielding performance of about 10 dB at 1 GHz, about 19 dB at 2 GHz, and about 28 dB at 3 GHz was obtained.

The reason why the electromagnetic shielding mortar 1 of the present invention has a higher shielding performance than the comparative mortar is considered as follows. That is, as shown in FIG. 3, the radio wave shielding in the comparative mortar is only the reflection loss on the mortar surface and the absorption loss when passing through the mortar (of FIG. 3),
Further, in the electromagnetic shielding mortar 1, loss due to reflection / diffraction by the metal powder solidified by cement (FIG. 3) and absorption loss by the metal oxide powder (FIG. 3)
This is because the electromagnetic wave is shielded by the combined action of.

In place of the blast furnace dust having the above composition,
Metal powders 3 and 4 called blast furnace secondary ash , which is a kind of ironmaking dust , cement 5 and water 6 are in a weight ratio of 1: 1: 0.
Using electromagnetic shielding mortar 1 kneaded at a ratio of 5, a confirmation experiment of the shielding performance was performed in the same manner as described above. The composition of the blast furnace secondary ash used in the experiment contained 30% by weight of Fe ₂ O ₃ and 10% by weight of carbon. The gas obtained by reducing iron ore in the blast furnace is discharged as dust-containing gas (blast furnace gas). Blast furnace secondary ash is dust collected during blast furnace gas cleaning and is dry
Alternatively, it is wet collected dust. The graph of FIG. 5 also shows the results of this experiment.

As can be seen from the graph of the blast furnace secondary ash in FIG . 5, the shielding performance of the blast furnace secondary ash kneading mortar 1 was about 12 dB at 1 GHz, about 18 dB at 2 GHz, and about 22 dB at 3 GHz. This shielding performance is about 6dB at 1GHz, about 9dB at 2GHz, and about 12dB at 3GHz, compared to the shielding performance of blast furnace dust-mixing mortar 1.
small. This decrease in shielding performance is considered to be mainly due to the fact that the amount of metallic powder in the blast furnace secondary ash is smaller than the amount of metallic powder in the blast furnace dust.

[0023] That is the graph of Figure 5, by adjusting the amount of metallic powder 3,4 kneaded in electromagnetic shielding mortar 1,
This shows that the shielding performance of the electromagnetic shielding mortar 1 for a specific frequency, that is, the transmission coefficient T can be adjusted. The present inventors, as a result of further experiments, by adjusting the thickness d of the dust kneading amount and panel material 16 composition and mortar in 1 steelmaking dust, the transmission coefficient of the predetermined level T ₀ for a particular frequency It has been confirmed that the panel material 16 of the electromagnetic shielding mortar 1 giving the above can be manufactured.

[0024] As shown in Fig. 2,
Transmission level T of wall 11 or slab 13 ₀ Is decided before casting
If it is, electromagnetic shielding mortar 1 or concrete 2
Wall 11 or slab with adjustment of the amount of metallic powder mixed in
A design of 13 casting thickness d is required. The present inventor
Electromagnetic shielding mortar 1 or concrete for thickness d design
Complex permittivity of REIT 2 ε = ε _r −jε _i (Hereinafter simply
Sometimes referred to as the ratio ε. ) Is available
Was. According to the dielectric constant ε, mortar 1 or concrete 2
Its own shielding performance per unit thickness can be determined.

[0025] That is, they generally have a uniform dielectric constant ε
The transmission coefficient T of a layer having a thickness d (single-layer model) is given by the following equation (2).
(IEICE Technical Report,
A ・ P95-47 (1995-09) “Reflection characteristics of building materials in millimeter wave band
Measurement of refractive index and refractive index "). Here, δ = (2πd / λ) (ε
−sin ^Two θ) ^1/2 , K ₀ = 2π / λ. Λ is a shielding target
The wavelength of the radio wave, θ, indicates the incident angle of the radio wave to be shielded. Equation (2)
R ′ of R ′s of the following equation (3) depends on the polarization of the radio wave to be shielded.
Alternatively, R'p in the following equation (4) is substituted.

[0026] For example, as shown in FIG.
If you think about it, electromagnetic shielding mortar 1 or concrete
The dielectric constant ε of 2 is determined by the thickness d of the panel material 16 and the radio wave to be shielded.
Based on the wavelength λ and the incident angle θ (vertical in FIG. 5),
Estimate so that the variance between the measured value of number T and equation (2) is minimized
(Hereinafter, for simplicity of explanation, go to equation (2)
Of the transmission coefficient T and the thickness d. ).
In the case of the blast furnace dust-mixing mortar 1 shown in the figure, 1GHz
At ε = 30-j10 at 3GHz, ε = 28-j16 at 5GHz
Then, it can be estimated that ε = 30−j25. In contrast,
Mortar in the frequency band of 1 to 5 GHz
Therefore, it can be estimated that the dielectric constant ε = 8−j1. This dielectric constant ε
Real part ε _r And the imaginary part ε _i The difference in the size of the mortar
Corresponds to differences in body shielding performance.

[0027]

(Equation 2)

[0028] Therefore, for example, the blast furnace dust dust kneading shown in FIG.
Using mortar 1, predetermined level T for 3 GHz band ₀ Through
When placing a wall or slab of building 10 that gives an excess coefficient
Gives the dielectric constant ε = 28-j16 for the 3GHz band of mortar 1.
The dielectric constant ε and the predetermined level T ₀ From formula (2)
The thickness d of the wall or slab to be cast
Can be.

Although the transmission coefficient of the electromagnetic shielding mortar 1 has been described above, the transmission coefficient of the electromagnetic shielding concrete 2 also depends on the composition of ironmaking dust , the amount of dust kneaded in the concrete 2 and the thickness d of the wall 11 or the slab 13. By adjusting
It can be adjusted in the same manner as in the case of the mortar 1. However, in the case of the electromagnetic shielding concrete 2, since the shielding performance decreases as the amount of the aggregate kneaded increases, the panel material 16 of the same thickness made of iron-made dust having the same composition is the same as the mortar 1. In order to obtain the above shielding performance, it is necessary to increase the amount of dust kneading as compared with the case of the mortar 1.

The present invention uses electromagnetic shielding mortar 1 or concrete 2 to form the walls and / or slabs of a shielding building.
Accordingly, the building body itself can be provided with an electromagnetic shielding function, and there is no need to provide an electromagnetic shielding member separately from the building body, so that the work of installing the electromagnetic shielding member can be omitted and the construction period can be shortened. Further, since the electromagnetic shielding mortar 1 or concrete 2 of the present invention can be integrally cast on an outer wall portion, a floor, or a ceiling portion of a building, leakage of a radio wave from a joint of the electromagnetic shielding member, which has conventionally been a problem, is reduced. be able to.

In this way, the object of the present invention is to perform “
Electromagnetic shielding of buildings that can be constructed and reduce leakage of radio waves
The provision of a " method " can be achieved.

[0032] Ironmaking dust is inexpensive because it is produced in large quantities as a by-product of the ironmaking process of an ironmaking plant. Therefore, the electromagnetic shielding cost can be reduced by using the electromagnetic shielding mortar 1 or the concrete 2 of the present invention using iron-made dust . However, even if appropriate metallic powders 3 and 4 other than iron-made dust are kneaded,
By adjusting the composition and kneading amount of the powders 3 and 4 and the thickness d of the panel material 16, a predetermined level T ₀ for a specific frequency is obtained.
Electromagnetic shielding mortar 1 or concrete 2 giving a transmission coefficient of

It should be noted from the prior art, molded by blending a steel-making converter dust and cement, weight Concrete structure Monoka has been proposed (JP-A 5-319880, JP-A No. 6-0248
No. 13). However, the conventional heavy concrete uses an inexpensive mixture of metallic iron and iron oxide in order to increase the density. By adjusting the thickness of the mortar or concrete, the shielding performance of which is enhanced by kneading the metallic powders 3 and 4. Construction
Techniques for shortening the period and reducing radio wave leakage have not been proposed so far. The present invention, Ri may der adjusted <br/> transmission coefficient T per unit thickness of the mortar or concrete by adjusting the kneading of the metal powder material elements 3,4, the mortar or con
Determine the thickness of building walls and slabs based on the dielectric constant of the cleat
This is based on the inventor's knowledge that desired shielding performance can be imparted to the walls and slabs of the building .

[0034]

1 (B) and FIG. 2 show a work site.
The electromagnetic shielding mortar 1 or the concrete 2 of the present invention is cast into a formwork (not shown) provided in a reinforced building 10 to form a wall 11 and / or a slab 13 of the building 10 as shown in FIG. 1 shows an embodiment of the invention. Reference numeral 14 in FIG. 1B indicates a concrete mixer, and reference numeral 12 in FIG. 2 indicates a deck plate. In the case of casting at the work site in this way, the required amount of the metal powders 3 and 4 in the mortar 1 or the concrete 2 and the casting thickness d are adjusted to the wall 11 or the slab 13 of the building 10. it is possible to impart the transmission level T ₀ in.

Further, the present inventor has compared the dielectric constant ε of the electromagnetic shielding mortar 1 or the concrete 2 with the shielding performance and found that the imaginary part ε of the dielectric constant ε was required to obtain a large shielding performance.
It was found that increasing _i was effective. The following Table 1 shows that the thickness d = 20 cm and the incident angle θ of the radio wave to be shielded = 0.
The calculation results of the relationship between the dielectric constant ε and the shielding performance for two types of shielding target radio waves at frequencies f = 1.2 GHz and 2.4 GHz, assuming the degree (normal incidence), are shown. As shown in FIG. 5, the shielding performance of the comparative mortar for frequencies f = 1.2 GHz and 2.4 GHz is 6 dB and 10 dB, respectively.

[0036]

[Table 1]

[0037] As seen from a comparison of the 6-9 column of Table 1, the shield also increase the real part epsilon _r of the dielectric constant epsilon performance is not necessarily increased. In contrast, the first in Table 1
As shown in to 4 column can be a shielding performance by increasing by increasing the imaginary part epsilon _i permittivity epsilon, reducing the transmission coefficient T. From this, electromagnetic shielding mortar 1
Or the composition and / or kneading of the metallic powder 3,4 for concrete 2, it is preferable to select as the imaginary part epsilon _i in the dielectric constant of the mortar 1 or concrete 2 epsilon increases.

As described above, the metallic powders 3 and 4 having a composition and an amount that give a large dielectric constant ε to the radio wave to be shielded.
There an electromagnetic shielding mortar 1 or concrete 2 which is kneaded, by pouring a thickness d providing a predetermined transmission level T _0, for example, an electromagnetic shielding function necessary for the wall 11 and the slab 13 itself of the building 10 in FIG. 2 Can be provided.

Further, as shown in FIG. 1 (C), a predetermined transmission level T ₀ by electromagnetic shielding mortar 1 or concrete 2
It is also possible to form an electromagnetic shielding panel member 16 having a thickness d that gives the electromagnetic shielding function necessary for the outer wall 11, the slab 13, and the partition wall of the building 10 using the panel member 16. When using a panel material in which the electromagnetic shielding mortar 1 or concrete 2 of the present invention and other building materials are combined in layers,
Instead of the one-layer model shown in the equation (2), the transmission coefficient of the panel material can be obtained by using a multilayer dielectric model.

[0040] Further, for example, when the shielding performance of the walls and the slab is insufficient, as the interior material on the walls 11 and slab 13,
By applying the electromagnetic shielding mortar 1 or concrete 2 of the present invention at a thickness d that gives a predetermined transmission level T ₀ ,
It is also possible to enhance the shielding function of walls and slabs.

It should be noted, for example, kneading mortar or concrete the steel dust exhibits a dark brown or dark brown, electromagnetic shielding mortar 1 or concrete 2 of the present invention is not inferior to the conventional plain mortar or concrete even when viewed from design specific colors . The contrast intensity and the specific gravity of conventional ordinary mortar (average value) is 54N / mm ² and 2.116, Ltd.
The strength and specific gravity of the mortar kneaded with iron dust is 63 N / mm ²
And 2.441, and the electromagnetic shielding mortar 1 of the present invention is also excellent in these points. It is also possible to use the electromagnetic shielding concrete 2 of the present invention as heavy concrete as seawall concrete or nuclear facility concrete.

[0042]

As described in detail above, the construction of the present invention
The electromagnetic shielding method of the object is a metal powder and / or a metal oxide powder.
Electromagnetic shielding mortar or concrete with kneaded body
Obtain the permittivity for the radio wave to be shielded and
The thickness of the wall and / or slab giving the desired shielding performance is
Determined based on the dielectric constant, and use an electromagnetic shielding mortar or concrete
By casting the sheet with the thickness specified above.
The formation of the wall or slab has the following remarkable effects.

[0043] (b) a metal powder and / or metal oxide powder <br/> composition, by adjusting the kneading amount, can provide an electromagnetic transmission level necessary to mortar or concrete. (B) Since the building body itself can be provided with an electromagnetic shielding function, it is possible to save time and labor for installing an electromagnetic shielding member separately from the building body, thereby shortening the construction period. (C) Leakage of radio waves from the joint of the electromagnetic shielding member, which has conventionally been a problem, can be reduced, and the possibility of deterioration of the shielding function is small. (D) The use of iron dust can be reduced in manufacturing cost, and can contribute to the recycling of steel dusts.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory view of a wall and a slab of a reinforced building.

FIG. 3 is an explanatory diagram showing the principle of electromagnetic shielding according to the present invention.

FIG. 4 is an explanatory diagram of a measuring device of electromagnetic shielding performance.

FIG. 5 is a graph showing the shielding performance of the mortar of the present invention.

[Explanation of symbols]

 1: Electromagnetic shielding mortar 2: Electromagnetic shielding concrete 3: Metalpowder 4: Metal oxidepowder  5 ... Cement 6 ... Water 7 ... Aggregate 10 ... Reinforced building 11 ... Building outer wall 12 ... Deck plate 13 ... Slab 14 ... Concrete mixer 16 ... Electromagnetic shielding panel material 20 ... Shield room 21 ... Electromagnetic absorption member 22 ... Partition wall 24 ... Network Analyzer 25… Transmitter 26… Receiver

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H05K 9/00 H05K 9/00 M // C04B 111: 94 (72) Inventor Taku Tsukada 2-9-1-1, Tobita Supplier Tobita, Chofu-shi, Tokyo No. Kajima Corporation Technical Research Institute (56) References JP-A-6-209180 (JP, A) JP-A-11-12014 (JP, A) JP-A-7-157356 (JP, A) JP-A Sho 61-68357 (JP, A) JP-B 52-19565 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 28/02 C04B 18/14 C04B 111: 94 C04B 14 / 30 C04B 14/34

Claims (7)

(57) [Claims] 1. A metal Fe, A of 50 to 300% by weight based on cement.
l, 50 to 50 for electromagnetic shielding mortar or cement mixed with Mg powder and / or oxide powder of these metals
0% by weight of the metal powder and / or metal oxide powder
Wall of specified thickness made of electromagnetic shielding concrete mixed with
Measure the transmission coefficient for the radio wave of the frequency to be shielded by the body ,
The dielectric constant of the mortar or concrete is obtained by substituting the measured transmission coefficient and the predetermined thickness into the relational expression of the wall thickness, the transmission coefficient, and the dielectric constant, to obtain a desired value for the radio wave of the shielding target frequency. The thickness of the wall and / or slab providing the shielding performance is calculated by substituting the dielectric constant into the relational expression, and the mortar or concrete is subjected to the calculation.
An electromagnetic shielding method for a building in which a wall and / or a slab of a shielded building is formed by casting with a fixed thickness. 2. 50 to 300% by weight of metal Fe, A based on cement
l, 50 to 50 for electromagnetic shielding mortar or cement mixed with Mg powder and / or oxide powder of these metals
0% by weight of the metal powder and / or metal oxide powder
Wall of specified thickness made of electromagnetic shielding concrete mixed with
Measure the transmission coefficient for the radio wave of the frequency to be shielded by the body ,
The dielectric constant of the mortar or concrete is obtained by substituting the measured transmission coefficient and the predetermined thickness into the relational expression of the wall thickness, the transmission coefficient, and the dielectric constant, to obtain a desired value for the radio wave of the shielding target frequency. The thickness of the wall and / or slab providing the shielding performance is calculated by substituting the dielectric constant into the above relational expression, and the mortar or concrete is applied to the surface of the building wall and / or slab at the calculated thickness. Thereby providing the said shielding performance to the building. 3. The electromagnetic shielding method according to claim 1, wherein
An electromagnetic shielding method for a building, wherein the electromagnetic shielding mortar is obtained by kneading 30 to 70% by weight of water with respect to cement. 4. The electromagnetic shielding method according to claim 3, wherein said electromagnetic shielding mortar is obtained by kneading an amount of fine aggregate of not more than 100% by weight with respect to cement to improve flexibility. 5. The electromagnetic shielding method according to claim 3, wherein
An electromagnetic shielding method for a building, wherein the metal powder and / or metal oxide powder is dust generated in an iron making process. 6. The electromagnetic shielding method according to claim 1, wherein
The electromagnetic shielding concrete, 30-500 to cement
An electromagnetic shielding method for a building that is obtained by kneading 30% to 70% by weight of water by weight of aggregate. 7. The electromagnetic shielding method according to claim 6, wherein said metal powder and / or metal oxide powder is dust generated in an iron making process.