JPS603106B2 - Method of laying radio wave absorbing asphalt composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of laying a radio wave absorbing asphalt composition for paving the ground or a board.

'. 'The fields that utilize conventional technology radio waves have increased significantly,
In addition, as the use of radio waves becomes more sophisticated, the number of cases of radio wave interference due to reflection of radio waves from various objects is increasing.

One way to prevent radio interference caused by the reflection of radio waves is to use radio wave absorbing materials that absorb unwanted radio waves. As is well known, radio wave absorbers are constructed using carbon powder, dielectric materials with high loss, or magnetic materials, and those using magnetic materials are particularly characterized by their relatively thin thickness and high performance.

In the early days, such radio wave absorbing materials were
As shown in No. 625, it was mainly used for research anechoic chambers. After that, special public service No. 50-40255
It is used in microwave heating devices such as microwave ovens, as shown in 1983, and is now being considered for application to building walls to prevent interference with television radio waves, as shown in Japanese Patent Publication No. 52-27355. It was boiled. Problems to be Solved by the Invention However, problems associated with reflection and interference of radio waves are not limited to those mentioned above, but include interference caused by reflection from the ground surface of radars at airports, and the ground surface around air beacon facilities. There are also problems with reflexes.

In cases where the ground surface or road surface is wide-ranging and traffic such as people and wheels on the surface must be considered, it is not just a matter of radio wave absorption, but also the ability to withstand the traffic on that surface and the construction aspect. There are problems such as ease of use. Conventionally, there has been no mention of such radio wave absorbing pavement. Conventional technology was designed for installation on the walls of buildings, whether indoors or outdoors, so no consideration was given to the material constituting the radio wave absorbing material to withstand traffic, that is, its load-bearing capacity and abrasion resistance. Furthermore, it was not a consideration to quickly and economically lay down the material over a large area such as the earth's surface. The inventors of the present invention have conducted intensive studies on a method of combining constituent materials with electromagnetic wave absorbing properties and constituent materials with load-bearing and abrasion resistance, etc., and quickly and economically laying them over a wide area, and have arrived at the present invention. It is something that
0 Means for Solving the Problem The present invention involves laying a metal plate on the ground or roadbed, and forming a layer of ferrite or an asphalt composition containing a mixture of ferrite and an inorganic dielectric as a filler on top of the metal plate.
Alternatively, a crushed stone layer is formed on a metal plate, and an asphalt composition made of ferrite or a mixture of ferrite and an inorganic dielectric material is laid on top of it as a filler, and the surface can be passed by people and vehicles, and it has radio wave absorption properties. It is designed to have both characteristics.

In the present invention, the radio wave absorption characteristics are obtained by mixing ferrite, inorganic dielectric (including aggregate), and asphalt, which is an organic compound, and laying this to a predetermined thickness on a metal plate laid on the roadbed. It is determined by FIGS. 1 and 2 show an example of the present invention, in which the crushed stone layer between the asphalt composition and the metal plate also functions as a layer of inorganic compounds. In this case, the thickness of all the layers is such that the normalized input impedance Z as seen from the surface is approximately 1 with respect to the intended interfering radio wave. The normalized input impedance Z is expressed by the formula {1-.

Z= Ima Misaki hi et al. m6r Here and there. is the complex relative magnetic permeability, r is the complex relative electric rate, ^ is the wavelength of radio waves in free space, and 1 is the thickness of the absorber layer.

Therefore, depending on the wavelength of the interference radio waves to be removed, it is possible to cope with the problem by changing the compounding ratio or thickness of the constituent materials. On the other hand, the asphalt composition layer and the crushed stone layer have other functions in terms of being easy to lay on the ground and withstanding the traffic of people and vehicles. That is, asphalt compositions are extremely suitable for quickly and economically forming a traffic-resistant layer over a wide area such as the ground. For this purpose, the asphalt performs the same function as regular asphalt pavement. The filler is ferrite or ferrite and an inorganic dielectric, and if necessary, aggregate is added to make the asphalt composition exhibit load-bearing properties and wear resistance. If the load is particularly large, it is possible to improve the load bearing capacity by changing the blend of the asphalt composition, and then to lay crushed stone underneath. As mentioned above, the mixing ratio of asphalt, ferrite, inorganic dielectric material, crushed stone, etc. and the thickness of the laying layer are related to both radio wave absorption characteristics and traffic resistance characteristics, and are related to the wavelength of the target interference radio waves and the amount of traffic. It needs to be determined taking into consideration the required load capacity, etc. As the ferrite used in the present invention, industrially produced ferrite, ferrite by-product from the treatment process of wastewater containing harmful heavy metals, and natural ferrite can be used. As the inorganic dielectric material, it is preferable to use one with a high electricity yield rate.The used waste catalyst, which is generated in large quantities in oil refining processes, has a main component such as alumina, which is expensive compared to cinnabar sand, etc., which is usually used as a filler. This is preferable because it has a yield rate. There are various asphalts that can be used in the present invention, including straight asphalt, propane-degraded asphalt, semiprone asphalt, flown asphalt, rubber-containing asphalt, resin-containing asphalt, and epoxy asphalt. In addition to stone powder and calcium carbonate, which are commonly used in asphalt pavement, asbestos, cement, gypsum, and fly ash can be used as fillers. Ordinary sand, screenings, crushed stone, etc. can be used as aggregate. As mentioned above, in the present invention, the composition of the constituent materials is determined from both the radio wave absorption property and the traffic resistance performance, but the filler asphalt preferably has a filler content of 70-9% by weight, which improves the mechanical properties of the filler asphalt. If necessary, 5-5% by weight of sand and 1-1% by weight of filler such as stone powder, asbestos, and cement are blended to obtain a blend similar to that of so-called sand asphalt or asphalt mortar. If even greater mechanical properties are required, 5 to 5% by weight of crushed stone or screenings may be added to the sand asphalt to obtain a composition similar to that of pongee-grained asphalt concrete. These formulations usually 1
This asphalt composition, which is mixed at a temperature of 20 to 18 degrees and then laid on the ground surface, has properties similar to ordinary asphalt compositions for pavement, so when laying it on the ground, a construction method similar to that of ordinary asphalt pavement is adopted. Therefore, it can be laid quickly and economically over a wide area. Note that the metal plate can also be replaced with a wire mesh if the wavelength of the target radio waves is long. According to the present invention, a radio wave absorbing surface on which people and vehicles can pass can be quickly and economically installed over a wide area such as the ground, and can be used to prevent radio wave interference.

N Examples Example 1 40-60 straight asphalt enriched with heavy metals from wastewater treatment process as filler.

Filler asphalt was prepared by adding hardened ferrite. The filler was previously heated to 150° C. to remove moisture sufficiently, and approximately 5 parts by weight of the filler was added to 100 parts by weight of asphalt heated to 18°C and mixed.
This was placed in a cylindrical frame with an inner 8-board side and a bottom plate, and 14
Compression molding was performed at 0qo and a pressure of 15 tons for 1 minute. After cooling to room temperature, the specimen was taken out of the mold and left overnight.
A penetration amount test was conducted on this specimen, and a value on the penetration amount side of 6 was obtained. Next, a part of the specimen was cut out using a diamond cutter and processed into a shape with 7 ribs on the outer diameter and 3 on the inner diameter.The coaxial cable was used as a sample holder, and the test piece was loaded at the end of the coaxial cable, and the coaxial slot line was fixed. The voltage standing wave ratio (VSWR) was measured using a wave measurement method. Table 1 shows the results of measuring VSWR while changing the thickness of the test piece. Table 1*
Blood: Frequency at which VSWR is minimum (matching frequency) For the blade mass part of filler asphalt 10 of Example 1,
Further, a Marshall specimen was prepared using a composition containing 2 parts by weight of waste silica alumina catalyst and 8 parts by weight of sand as fillers, and a Marshall stability test was conducted.

The results obtained were a Marshall stability of 810k9 and a flow value of 32 (1/10 cucumber). Next, a female ring-shaped test piece with an outer diameter of 7 sails, an inner diameter of 3 ribs, and a thickness of 4.8 mm was manufactured in the same manner as in Example 1, and when the VSWR was measured, the matching frequency value was 920 Hz, VSWR at fm is 1.
It was 06. Example 3 Ferrite 100 of Example 1
One part by weight of asphalt emulsion (asphalt content: 55% by weight) was added and mixed to prepare a slurry-like composition, which was then applied with a trowel to a two-board thickness on an aluminum slope with a low diameter.

After standing for a day and night, the specimen was subjected to a 7-bar abrasion tester to measure its abrasion resistance. Wear loss was 555 females. Next, the slurry-like composition was molded into a ring shape with 7 ribs on the outside diameter, 3 sides on the inside diameter, and 4.8 ribs in thickness using a mold, and the VSWR was measured in the same manner as in Example 1, and it matched. Frequency fm'ma6. VSWR at Hz and fm is 1.
It was 06. Example 4 After mixing 100 parts by weight of the ferrite of Example 1 with 30 parts by weight of epoxy asphalt (epoxy resin content: 4% by weight) and a hardening agent, 2 parts by weight were placed on an aluminum plate with a diameter of low side. It was applied to a willow-thick layer with a trowel and left to harden at room temperature overnight.

This specimen was subjected to a Taber type abrasion tester to measure its abrasion resistance. The wear loss was 1.0 mo. The compressive strength of the test piece, which was obtained by putting the sample into a cylindrical mold with an outside diameter of 20 mm and a height of 4 arms and curing, was 5 kg/m. Next, the mixture was molded into a ring shape with 7 ribs on the outside diameter, 3 sides on the inside diameter, and 5.5 ribs in thickness using a mold.
When I measured the SWR, the matching frequency fm was 31 GHb.
VSWR at fm was 1.08. ...Effects of the Invention By laying a metal plate on the ground or roadbed, forming a crushed stone layer on top of it, and then laying ferrite or an asphalt composition containing ferrite, an inorganic dielectric material, and aggregate as a filler on top of the metal plate, the ground or roadbed is laid. A radio wave absorbing surface having mechanical strength that can withstand human and vehicular traffic can be quickly and economically installed on the roadbed, and radio wave interference can be prevented.

Furthermore, it is extremely economical to use ferrite as a filler, which is a by-product from heavy metal wastewater treatment, and waste catalyst as an inorganic fin body.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of the asphalt composition of the present invention installed. 1 is an asphalt composition layer of the present invention, 2 is a crushed stone layer, 3 is a metal plate, and 4 is a roadbed. Traditional map Figure 2

Claims (1)

[Claims] 1. Lay a metal plate on the ground or roadbed, and form a layer of ferrite or an asphalt composition containing ferrite and an inorganic dielectric in part or all of the filler on the metal plate, or A method for laying a radio wave absorbing asphalt composition, which comprises forming a crushed stone layer on top of the crushed stone layer, and forming a layer of an asphalt composition containing ferrite or a mixture of ferrite and an inorganic dielectric on part or all of the filler. 2. A method for laying a radio wave absorbing asphalt composition according to claim 1, which comprises mixing aggregate in addition to filler into the asphalt. 3. A method for laying a radio wave absorbing asphalt composition according to claim 1, characterized in that a waste catalyst is used as the inorganic dielectric. 4. The method for laying a radio wave absorbing asphalt composition according to claim 1, characterized in that ferrite which is a by-product from heavy metal wastewater treatment is used as the ferrite as the filler.