CA2134143A1 - Method and bed material for installing road heating - Google Patents

Abstract

Abstract This invention is to provide a road heating method and bed material which make possible to install in an extremely short period of time the concrete layer surrounding the heating source, regardless of the shape of the construction area, and which raises the thawing efficiency above conventional concrete layers.
To achive this suject, this invention is to be comprises forming an adiabatic bottom layer through placing gravel at the base of an excavation and arranging thin aluminum foil on the surface of this gravel, then introducing a mesh material on the the surface of said aluminum foil and placing down the means for heating, then placing a water permeable thin film material on top of said means for heating, and then taking an adiabatic top layer by arranging dry sand and cement mixed at a ratio of approximately 3:1 on top of this, and finally applying surface finishing materials on top of this adiabatic top layer. Moreover, in order to make the state of installation better, the above-mentioned aluminum material that is arranged on the ground may comprise, for instance, aluminum foil tape with a thickness of 0.5-1.5 mm and a top-to-bottom width of 3-7 mm that is formed into the shape of a spiral, wherein the width of the spiral is shaped to 5-15 mm; furthermore, in order to raise the thawing efficiency, there are cases in which the aluminum material is mixed with a transition metal and/or silica.

Description

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Field of Invention :r This invention relates to kechnology for installin~ road heating, in particular ieProving the installation arollnd the heating pipes.

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Prior Art .
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In installing road heating9 it i5 import~nt firstly to realize good ::"
ther~al efficiency, and secondly to si~plify the installation.
Figure 3 illustrates a different exa~ple of a conventional installation method wherein installation is carried out efficiently by , passing hot water pipes 2 through blocks with fixed dimensions 1, and wherein said blocks are spread out in large nu~bers ~Japanese , Laid-Open UtilitY Model Sho 51-530~
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~igure 4 also illustIates a different example of a conventional installation ~ethod wherein9 on the one h~nd, arl upper layer A and a louer layer B are for~ed on both sides of the heating source Nith the i~ upper layer A being given a high khermal conductivity, and wherein the lower layer B is given the function of preventing heat radiation i (Japallese Laid-Open UtilitY ~lodel Sho 48-1253~). UPPer layer A9 on the one handl is nlulled with coarse aggregate 4 and ce~ent, synthetic ;` resiny and gypsua7 for coarse aggregate 4, earth7 stones~ metals9 .
etc., with high ther~al conductivity are used. ~n the other hand9 lo~er layer B uses for coa~s~ a~gre~ate 5 lapilli sand, Yer~iculite~
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2~3~3 ex~anded shale and other materials which are hi~hly adiabatic, this prevellts the heat of heat source 3 fro~ escaping into the ground.

This being the case, the conventional road heating installation methods related have the fol]owing respective problc~s.

In respect to the ~ethod of first placing hot water pipes in blocks and then laying down said blocks, there ;s the problem that in many cases these cannot match the shape of the place where they are to be laid; moreover, there is also the proble~ of poor ~orkability because it is necessary to connect the ~1ater pipes a~ong the blocks that adJoin each other. ~he places where the blocks ar~ to be laid have various shapes and areas, and thus it is impossible to esti~ate the block shapes beforehand. ~or this reason9 the area in which the blocks can be laid do~n is restricted to prescribed limiSs into which square blocks can be fitted; in the surrounding areas blocks cannot be laid do~n. Even supposing the blocks were laid out on a order ~ade basis, the cost would be high. Moreover, because hot water pipe co~plings are :`:
required, the connection work of this part ;s coi~plicated, and thus it cannot necessar;ly be said that the workability is satisfactory. In , addition, after installation, there is a great possibility that a prcble~ such as uater leakage could occur through the bending of the coupl;ng part when the road surface bears a great load, or when the . ~
ground shifts due to an earthquake and/or other causes.
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On the other handg ;n respect to the method of forl~in~ a ther~all~
conductive layer above and an adiabatic layer oelow the heating ¦ source9 this can exhibit characteristics that surpass gcneral concrete ,.. , .
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21~:193 installations in regard to thermal efficiency. However9 there are problems in that, because the basic ~aterial for both the upper and lower layers is cement to ~hich water is added and placement is carried out after mulling, in addition to requiril:g time to cure the concrete, winter construction is impossible. What llinders winter construction is that problems occur, such as on the one hand, the costs that are incurred and the complicated supervision of curing when heated curing is carried out to prevent the water of placed concrete fro~ freezing, and that when these measures are not taken the water of the concrete free~es generating Many small cracks that after~ard progressively break due to loads borne by the road surface, and thus warp and destroy the heating source. ~or this reason, the explanation of the Practical Example of Japanese ~aid-Open ~tility Model Sho 48-125~3 describes to the effect that the upper and lower layers are formed as blocks using a form~ork. However, the problem of block materials is as ~as pre~iously eRplained7 and the workability of the ~., eouplings is poor. In khe case ~here electrical resistance wires are arranged, the ~ork costs are high in a different sense fro~ hot water pipes in that connections haYe to be insulated9 noreover, there is also the possibility of broken wires and other malfunctions.

The reason that block installation has been proposed in spite of the fact that there are such high costs and restrictions on placement, and also co~plicated connection of the heating source, is because concrete curing at the placeoent location requires ~ long ti~e, and thus there ~; are such problems as blocking traffic during that time; and also ~` because when insuficient curing occurs, the placed concrete layer breaks, and thus there are such yroblems as fissures appearing in the surface roadbed. Moreo~er, the adoption of an installation ~ethod in '.
~' ~ ~ 3 ~ 3 which adiabatic materials such as polYstyrene foa~ are placed at the bottom of the heatin~ source is because it has become known that moisture collects around the heating source (resistance wires7 hot water pipes) since the adiabatic resin layer checks the moisture, and hen that freezes, damage is caused to the heatin~ source.

Accordingly, it ;s an objective Or the present invcntion to proYide a road heating method and bed ~aterial which make possible to install in an extreoely sbort period of ti~ne the concrete layer surrounding the heating source~ regardless of the shape of the construction area, and ~hich raises the thawing efficiency abo~e conventional concrete layers.

Summary of the inventic)n The road heating installation method based on the present invention for achieving the above-~entioned obJective col~prises forming an adiabatic bottom laYer throu~h plaeing ~ra~el at the base of an excaYation and arranging thin aluminu~l foil on the surfase of this gravel9 then introducing a mesh material on the the surface of said aluminum foil and plac;ng down the means for heating9 then placing a water perneable thin film material on top of said means for heating~
and then mak;ng an adiabatic top layer by arrang;ng dry sand and cement D~ixed at a ratio of approximately 3~1 on top of this9 and finally apply;n~ surface finishill~ materials on top of this adiabatic top layer. Moreo~erg in order to make the state of installation better9 ihe abo~e-melltioned aluminum material tllat is arran~ed on the ground may comprise7 for instance7 aluminum foil tape with a thickness ~;

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2~3~ 3 of 0.5-1.5 mm and a top-to-bottom width of 3-7 mm that is formed into the shape of a spiral~ wherein the ~idth of the spiral is shaped to 5-15 mm; furthermore, in order to raise the thawin~ effic;ency, there are cases in ~hich the aluminum material is oixe~ with a transition mctal and/or silica.

The thin aluminum material that is arranged on the ground to or~n the bottom layer9 in addition to functionin~ as a cushioning saterial at the beginning of installation, perfor~s the function of raising ther~al eff;ciency by radiatin~ and d;ffusing heat absorbed from the ~eans for heating. On the one hand, the top layer formed on top of the means for heating such as hot water pipes9 displays a hi~hly adiabatic nature by means of large numbers of voids between particles at the ~eginning of installation, and also efficiently transfers the heat of the means for heating up to the sur~ace road by means of the large nusbers of voids. Moreover, the top layer doss not freeze even throu~h ~inter installation7 and does not require any curing process, because it does not include ~ater, although it uses cement.

OD the other hand~ when thc top and bott;om layers are formed in this manner, ooisture slo~ly permeates into the cement of the top layer through the evaporation of ~oisture in the earth, and ovcr a long period of time a solidify;ng effect begins in the top cenlent layer.
At this time~ the cemcnt that absorbed the moisture penetrates downward through the effect of gravity and reaches the aluminum level where it hegins to solidify the bottom layer part aiso.

Si~ultaneously, certain types of bacteria (n~icroorganlsms) that exist .; .
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in the earth be~in eating the aluminum foil that ~1as arranged on the ground. Thc aluminum foil progressively hardens slowly due to the cement layer with the passage of time; because the aluminum itself is eroded by the microorganisms, when viewed after a period of 3-6 years, the cement that hardens down in the bottom layer part cones to have innu~erable erosion paths due to the erosive action of microorganisms and/or by other causes. These erosion paths e~tend in all directions in unlimited lengths. The top layer is not eroded by the microorganisms. However9 since the ori~inal material is a dry cement ~aterial, the grains become coarse, and it hardens while forming large nuMbers of microscopic voids even as solidification progresses.

A period e~tending 3-8 years is required until the top and bottom layers conpletely solidify and the aluminum material is com~letely eroded a~a~. Dur;ng this period, ~icroscopic cavities slo~ly multiply in the concrete layer. The aicroscopic cavities that -form inside tlle concrets layer are different from cracks and do not cause breaking of the concrete layer. Moreover9 through the air stored inside the oicroscopic cavities9 on the one hand, the concrete layer by itself functions as an adiabatic naterial blocking unnec~ssary radiation of the heating source9 and because thermal emission from the microscopic cavities hecomes possible, theroal conduction to the surface roadbed goes ef~iciently and raises the thawing efficiency.

~urthermore9 the alunlinum material that forms the bed layer init;ally serves as a cushion material, and thenceforth it gives rise to erosion by microorganisms and/or other causes. Although it is acceptable if this aluminum material is a simple material that can be cut throll~h9 in order to make it work more functionallY9 it is desirable to form it . : :

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into a spiral shape so that greatcr numbers of voids are set in.
Moreover, because the erosion of the microorganisms requires a long period of time, during that ~ime the cement permeates into the cavities. The result is that the cavity shapes that are ultimately completed do not neeessarily match the shape of the aluminum material.
Also, in appropriately adjusting the diameter of the erosion cavities for~ed by the microorganisms and~or other causes9 it is necessary to set the thickness, length, and width of the alu~inum material respectively to fixed values; it is possible to obtain the most desirable results with the above-nentioned values for these dimensions.
When transition metals such as nickel, manganese, and copper9 or far infrared emitting materials such as silica are mixed to this aluminum material, the thawing efficiency is raised a step higher.

Brief description of the drawings ~igure 1 is a cross section that illustrates an cxa~ple of road heating installation based on the present method.
~i~ure 2 is a perspective diagram that illustrates one example of the al uminum material based on the present invention.
~igures 3 and 4 are diagrams that illustrate conventional road heating i nstallation technology.

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~3~ ~3 Description of the preferred embodiment Below, ~ practical example of the present inven~ion is explained refering to the appended dra~ings.

Figure 1 illustrates an example of road heatin~ installation based on the present invention in which the bottom layer 20 is macle by placin~
cut^out aluminum on top of a bed material 10 formed from sand and gravel; hot water pipes 16 are placed on top of` this bottom layer 20 after sheets of hemp 14 are put down. Then, in order to restrain the inovement of the hot water pipes 16, a net 17 i5 laid down, after which a top layer 19 is formed by piling on top dry ~ranules mi~ed from sand and celnent. Afte~ this, ground leveling is carried out with rollers or other means for leveling3 and asphalt R is laid down on the surface.

This installation work is finished in an extrecely short period oE
time. This is because it is possible to make the top layer 19 just by scattering dry sand and ceoent ~itbout conventional eoncrete placement9 ~round ~eveling it in that state9 and then immediately covering it with asphalt R. Ilere9 it is desirable for the cut-out aluminuln that forms the bottom layer 20 to ha~e a shape that allows it as cuch as ~ossible to possess space internally.

To this end9 for the cut-out aluminum that constil;utes the bottom layer 20~ a spiral shape cut out to a fi~ed lengtn is used, as is sho~ln in ~igure ~7 for examl)le. This cut-out alum;num 21, is alulninum foil tape with its thick~ess set to ~.5 mm and its top-to-bottom width ~W) set to 5 mln9 for e~ample, and wllich has beell formed into a spiral ,~.. ::.:, ; , - -- -:: ." ~
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2~3~3 shape by rotating it about 3 twists. The width of the spiral (L) is set ~o, for example, 10 ~. These values for the dimen~ions ean be reset to suitable values in response to the environment of utilization.

The installation method based on the present invention, in addition to simple construction work, is characterized by the point that the thawing efficiency slowly improves after construction. This effect is as followsO

~irstly, in the initial state of installation, the alu~inum ~aterial 21 of the bottom layer 20 radiates and diffuses heat absorbed from the hot water pipes 16. Due to tbis, the heat loss of the hot water that circulates through the hot water pipes 16 is hept to a minimum.
Moreover9 the top layer 19 and the asphalt R are ~armed by the diffused heat of the aluminum material itself 219 which raises the tha~ing efficiency significantly higher. On the other hand, the top layer 1~ displays a highly adiabatic nature due to the large number of voids between particles at initial installation. Moreover, by mcans of the large number of voids, the heat of the water pipes 18 and the aluminum matelial 21 is efficiently sent to the asphalt R.

When the top and bottom layers 19, 20 are formed in this manner, i~ediately after installation moisture slowly permeates into the ce~ent of the top layer 19 and a solidification effect in the top cement layer (19) begins. At this time, the cement that absorbed the moisture spreads downward due to the effect of gravity, reaches the aluminum layer, and begins to solidify tbe bottom layer part 20 also.
The time until the aluminum layer at the bottom is completely hardened ,, . :.

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~3~ ~3 by the concrete is approximately 1-6 years as the slow solidification effect progresses. During this time, the abovc-mentioned heating effect continues.

Moreover, in simultaneous progression witb this solidification effect, certain types of bacteria (microor~anisms) that exists in the earth begin to eat the aluminium material 21. Through the erosion of the aluninum by these bacteria and/or by other causes, innumerable erosion paths are for~ed in the solidified cement portion of the bottom layer 20. The erosion paths e~tend in all directions in unlimited lengths.
The ti~e for the sicroorganisms to finish eating the aluminu~ material 21 is approximately 3-6 years. In the bottom layer 20 that is eroded away9 aluminum material 21 does not remain. Only the erosion paths remain. ~urtheroore, the top layer 19 is not eroded by the ~icroorganisms. Ilowever, because the original ~aterial is a dry cement material, the grains are coarse; even ~hile solidification is in ~rogress, it hardens while formiDg innumerable s~all voids.

During the period in which the erosion of the aluminu~ material by nicroorganis~s and~or other causes progresses, ~icroscopic cavities slo~ly increase in the top and bottom concrete layers (19, 20). Air is stored in the microscopic cavities that for~ inside the concrete layers. Through these air-filled cavities, the top and bottom layers function as adiabatic materials, blocking the unnecessary radiation of the heat source, on the one hand, and thermal emission from the microscopic cav;ties becones possible, ~7hich improves thermal transfer efficiency to the asphalt R.

Accordirgly7 by neans of this insiallation ~ethod~ as the erosion of *: . . . . -r/ ~
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the aluminum material by microorganiscs and/or other causes progresses, and as innumerable microscopic cavities increase inside the eoncrete layers, the thawing efficiencY increases more and ~nore.
In other ~ords, even at the initial stage of installation, it possesses ~ore voids th~n conventionally installed concrete and displays high thermal efficier.cy; with the passage of time, its tilermal efficiency continues to further improve. When the top and botto~ concrete layers ~19, 20) completely solidify and the alumi~um material 21 is çoMpletely eroded away9 it displays its maximum characteristics in terms of thermal efficiency.

In the severe winter period of Hokkaido, when a general thawing boile is used> and when the water temperature of the hot water is normal, without raising it to no more than approximately 70 ~C at tlle highest, it takes roughly 40 einutes from starting a boiler until the Inaxi~um temperature is attained. However, in areas wnere the present installation ~ethod has been appliecl, using the same type of boiler9 it has been confirmed that the hi~h temperature of 70 C or more is attained in about 17 minutes, and that it is possible to thaw rapidly.
It goes without saying that the fuel efficiency of the boiler improves dramatically.

Moreover, by means of this installation ~ethosl, it is possib1e to also holcl down the numbel of hot water pipe couplings to a minimum~ without restrictions as to the shape of the installation area. ~urthermore, as fon the ~eans for heating, it is not limits~d to hot water pipes; ii; is acceptable to use electrothermic ~ires also. With lhe present instal:lation7 concrete curing is not required Because of this7 it is possible to carry out construction even in periods when conventional . .
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~3~ ~3 installation work has been difficult, such as sevcre winter. This is because there is no dan~er that the water in the concrete will free~e.
Moreoverr since concrete curin~ is not required, the construction ti~e can be greatly reduced. Also, since it is not necessary to knead thc concrete by addin~ water, work costs also decrease ~itnout the troublc required in coocrete placement.

In order to raise the thawing efficiency in the initial period after installation i5 completed, raising the radiation effect of the alu~inum material is desirable. ~or this reason~ there are cases in which certain materials ~ith a far infrared emitting effect9 for example a transition Inetal or silica, are mi~ed with the aluminum scraps 21. As for transition Inetals, there are, for e~ample, nickel, cobalt, iron, magnesiuln, zinc, ~anganese9 titaniu~, lead~ etc.; by mi~ing fine amounts of these metals7 the aluminum scraps 21 emit more of the heat they have absorbed outward~

Moreover9 as for materials that psrform the same function~ there are silica, ferrousJferric salt9 and platinum~ When a transition metal and platinum or ferrous/ferric salt are mixed with silica and that compound material is added to aluminum, the far infrared e~ission effect is raised one step. In this case9 the const;tuent ratio of aluminum is 55~-99~; it is possible to increase or decrease the aluminuc ratio to a suitable level in accordance with the en~ironlnent o-f use.

Because this far infrared ef-rect is a comparati~ely incipient effect up to the passa~e of about three years after installation is completedt in order to raise the adiabatic effect thereafter, it is , .
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desirable to increase the aluminu~ co~ponent so as to e~tend the erosion paths; accordingly, the alu~inum distribu~ion ratio cannot but be changed in keeping with the environ~ent of use and the conditions of the specification.

Moreover9 the mesh material that is placed on to? of the aluminum oaterial prev~nts the settl;ng of the hot water pipes (or electrothermic wires). As long as it can transmit the moisture in the earth and does not prevent the natural sinking of the cement and the acti~ities of the ~icroorganismsD the raw mat~rial for this mesh material cannot be restricted to its type, such as metailic mesh, h0Mp, or fine resin mesh. As for the thin film material that is placed on top of the ~eans for heating, ~pipes or electrothermic wires), it is possible to use water permeable hemp, paper, or metallic or resin mesh7 sincc these prevent the rapid falling of the dry cement granules.

As was explained above, by means of the road heating installation ~ethod based on the present invention, it becomes possiblc to install in an e~tremely short period of ti~le the concrete layer surrounding the heat source without regard to the shape of the construction area.
The tha~ing efficierlcy also rises dramatically.

While the invention has been explained with reference to a specific embodiment, it is to be noted that tile description is illustrative and the invent;on is li~ited only by the appended clai~s.
What is claimed is;

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Claims (2)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
   PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   (1) A method for installing road heating which comprises the formationof an adiabatic bottom layer through placing gravel at the base of an excavation and arranging thin aluminum foil on the surface of this gravel, and the creation of an adiabatic top layer through introducing a mesh material on the the surface of said aluminum foil and placing down a means for heating, then placing a water permeable thin film material on top of said means for heating, and then arranging dry sand and cement mixed at a ratio of approximately 3:1 on top of this, and finally applying surface finishing materials on top of this adiabatic top layer; the method further comprises:
   (2) A bed material for road heating comprising the aforementioned aluminum material to be arranged on the ground, said aluminum material comprising aluminum foil tape with a thickness of 0.5-1.5 mm and a top-to-bottom width of 3-7 mm that is shaped into a spiral, wherein the width of said spiral is 5-15 mm.
   (3) A bed material for road heating mentioned in the aforementioned
2. Claim 2 comprising an aluminum material formed through mixing with a transition metal and/or silica.