JP5310280B2 - Water retention ceramics and water retention structures - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramics for water retention which has high water retainability, and in which the evaporating properties of water which has been involved is satisfactory, and which has high cooling effect by the evaporation latent heat of water, and to provide a water retaining structure using the ceramics for water retention. <P>SOLUTION: The ceramics 20 for water retention is composed of a sintered porous ceramics, and has a vent hole 21 with an inside diameter of &ge;1 mm communicated to the outside. In the whole volume, 53 to 70% is composed of pores with a pore size of 1 to 100 &mu;m. The vent hole may be passed through the pillar axis direction of the ceramics for water retention or may be passed through the horizontal direction. The vent hole may be provided by two or more or may be provided to two or more directions. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a water retention ceramic that is excellent in water retention and in which water that has been retained easily evaporates, and a water retention structure that uses this water retention ceramic.

  Japanese Patent Application Laid-Open No. 2003-184199 describes a cooling wall body in which water is applied to a wall body of a block made of porous ceramics to obtain a cooling effect such as hammering water by latent heat of evaporation. In paragraphs 0026 to 0027 of the same publication, porous ceramics produced by utilizing the foaming action of vermiculite during firing are described. However, such a foamed ceramic sintered body has coarse pores and does not have high water retention.

  In paragraph 0005 of JP-A-8-73282, a method for producing a porous ceramic is described in which clay, a water-absorbing polymer and water are kneaded, molded, dried in a microwave oven, and then fired at 1100 ° C. for 2 hours. Yes. The same publication discloses that the water-absorbing water-absorbing polymer has a particle diameter of 0.1 to 2.0 mm (claim 4). Thus, when the particle size of the water-absorbing polymer is large, the pores of the porous ceramics are also coarse, and the water retention of the porous ceramics is not high.

JP 2003-184199 A JP-A-8-73282

  The present invention provides a water retention ceramic having high water retention, good evaporation of stored water, and high cooling effect due to latent heat of water evaporation, and a water retention structure using the water retention ceramic. With the goal.

The water-retaining ceramic according to claim 1 is a water-retaining ceramic made of sintered porous ceramics, and the composition of the ceramic constituting the water- retaining ceramic is SiO ₂ : 50 to 80 wt%, Al ₂ O ₃ : 10 30 wt%, Na ₂ O and K ₂ O in total 1 to 10 wt%, and has a vent hole with an inner diameter of 1 mm or more , and the total porosity of the ceramic for water retention (the porosity does not include the volume of the vent hole). Is 55 to 80 wt%, 53 to 70% of the total volume of the water retaining ceramic is composed of pores having a pore diameter of 1 to 100 μm, and 60% or more of the pores having a pore diameter of 1 to 100 μm is composed of pores having a pore diameter of 10 to 50 μm. It is characterized by this.

Water retention ceramics for 請 Motomeko 2 Oite to claim 1, wherein the vent hole is plural, it is characterized in that is provided substantially in parallel.

Water retention ceramics according to claim 3 is characterized in that Oite to claim 1, vent extending in different directions are provided.

According to a fourth aspect of the present invention, there is provided the water retention ceramic according to the third aspect, wherein at least some of the vent holes having different extending directions intersect each other.

The ceramic for water retention according to claim 5 is the ceramic according to any one of claims 1 to 4 , wherein the ceramic for water retention extends in a column axis direction, and the vent hole extends in the column axis direction. It is characterized by being.

The ceramic for water retention according to claim 6 is the ceramic according to any one of claims 1 to 4 , wherein the ceramic for water retention has a column shape extending in a column axis direction, and the vent hole extends in a direction intersecting with the column axis direction. It is characterized by existing.

A water retention structure according to a seventh aspect is obtained by distributing the water retention ceramic according to any one of the first to sixth aspects to a building or a ground surface.

The water retention structure according to an eighth aspect is characterized in that, in the seventh aspect , at least a part of the vent holes are directed in the vertical direction.

A water retention structure according to a ninth aspect is characterized in that, in the seventh aspect , at least a part of the vent holes are oriented in the lateral direction.

A water retention structure according to a tenth aspect is characterized in that, in the ninth aspect , the water retention ceramics are arranged so that the air holes of the plurality of water retention ceramics are connected in a straight line.

The water retention structure according to claim 11 is the water retention structure according to any one of claims 8 to 10 , wherein a ventilation plate is disposed with a ventilation gap between the building and the ground surface, and the water retention ceramic is provided on the ventilation plate. Is characterized by being distributed.

  The water retention ceramic of the present invention is made of porous ceramics and exhibits a cooling effect by the latent heat of vaporization of the contained water. In the present invention, since the water retaining ceramic is provided with a vent hole having an inner diameter of 1 mm or more, water can easily penetrate into the deep part of the water retaining ceramic, and the water embedded in the deep part of the water retaining ceramic is also easily evaporated. . Therefore, the water absorption speed and evaporation speed are large.

  In one aspect of the present invention, the water retention ceramic comprises 53 to 70% of pores having a pore diameter of 1 to 100 μm. Thus, the water retention ceramic having a large amount of relatively fine pores has high water retention, a large specific surface area on the surface, and good water evaporation. Accordingly, it is possible to quickly absorb a large amount of water by rain or water spray and prevent urban flooding. In addition, the pores of this pore diameter are not ultrafine. When freezing, the water in the pores is rapidly pushed out of the water retaining ceramic with the volume expansion of the water at the time of freezing. However, there is almost no risk of cracking.

  As described above, large latent heat is removed from the retained ceramics of the present invention by water evaporation. Therefore, the water retention structure of the present invention in which this water retention ceramic is spread on the rooftop or garden of a building is excellent in the cooling effect of the building or garden.

  In the present invention, the above effect is enhanced by providing a plurality of vent holes substantially in parallel or extending in different directions.

  By crossing the vent holes extending in different directions, the vaporized inside the water retaining ceramic flows in a plurality of directions and flows out of the water retaining ceramic, so that the transpiration efficiency is high.

  When the water retaining ceramics are laid down so that the ventilation holes are directed in the vertical direction, the rain or water spray flows down the ventilation holes and quickly reaches the deep part of the water retaining ceramics.

  When water retaining ceramics are laid down so that the air vents are oriented in the lateral direction, vapor evaporated from the water in the deep part of the water retaining ceramics flows laterally and flows out of the water retaining ceramics. In this case, the transpiration efficiency is high by connecting a plurality of water retaining ceramic vents in a straight line.

It is a perspective view of ceramics for water retention concerning an embodiment. It is a perspective view of the ceramic for water retention which concerns on another embodiment. (A) The figure is a perspective view of the ceramic for water retention which concerns on another embodiment. (B) The figure is the BB sectional drawing of (a) figure. It is a perspective view of the ceramic for water retention which concerns on different embodiment. It is a horizontal sectional view of ceramics for water retention concerning still another embodiment. It is sectional drawing which shows the water retention structure which concerns on embodiment. It is the VII-VII sectional view taken on the line of FIG. It is explanatory drawing of the test method in an Example and a comparative example, (a) A figure is a top view, (b) A figure is the BB sectional drawing of (a) figure. It is a pore size distribution map of the ceramics for water retention of Experimental Examples 1-5. It is a hole diameter distribution map of the pores of the ceramics for water retention of Experimental Examples 6-10. (A) The figure is typical sectional drawing which shows the test body 1, (b) The figure is a graph which shows the time-dependent change of the slab temperature of the test bodies 1-3. It is a graph which shows a time-dependent change of the slab surface temperature of the test bodies 1 and 3. FIG. (A) The figure is typical sectional drawing which shows the test body 4, (b) A figure is a graph which shows the time-dependent change of the upper atmospheric temperature of the test bodies 4 and 5. FIG. It is a graph which compares the initial stage and the maintenance cost of cases 1-3. It is a graph which shows by contrast the amount of transpiration and water absorption in the test period of water retention ceramics and lawn. It is a graph which shows the cumulative total of the amount of transpiration and water absorption of ceramics for water retention and lawn. It is explanatory drawing of the test method in an experiment example, and is a schematic diagram which shows the accumulation state of the ceramic for water retention on a pallet.

  Hereinafter, the present invention will be described in more detail.

[Shape of ceramic for water retention]
First, an example of the shape of the water retaining ceramic will be described with reference to FIGS. 1 to 5.

  The ceramic for water retention of the present invention is made of a sintered porous ceramic and has a vent hole having an inner diameter of 1 mm or more communicated with the outside.

The water retention ceramic 20 of FIG. 1 has a cylindrical shape and has a vent hole 21 penetrating a column axis portion in the column axis direction. The height H of the water retaining ceramic 20 is preferably about 10 to 300 mm, particularly about 20 to 100 mm. The diameter (outer diameter) D0 of the ceramic 20 for water retention is preferably about ₁₀ to 300 mm, particularly about 20 to 100 mm. The inner diameter D1 of the vent hole 21 is preferably about ₁ to 200 mm, particularly about 5 to 50 mm. The wall thickness W between the inner peripheral surface of the vent hole 21 and the outer peripheral surface of the water retaining ceramic 20 is preferably about 3 to 50 mm, particularly about 5 to 30 mm.

  In the water retention ceramic 20 of FIG. 1, only one vent hole 21 is provided, but two or more may be provided. FIG. 2 shows a water retaining ceramic 22 formed into a honeycomb shape by providing a large number of air holes 23. The preferable range of the diameter and height of the water retaining ceramic 22 is the same as that of the water retaining ceramic 20. When two or more vent holes are provided in the direction of the column axis, the total cross-sectional area of the vent holes is 10 to 90% of the cross-sectional area of the water retention ceramic, particularly 30 to 30 It is preferably about 70%.

  In FIGS. 1 and 2, the vent hole extends in the column axis direction, but may be provided in a direction crossing the column axis direction, for example, in an orthogonal direction. In the water retaining ceramic 24 of FIG. 3, two vent holes 25 are provided in a direction orthogonal to the column axis direction. In this embodiment, the air holes 25 are parallel to each other. A preferable range of the diameter and height of the water retaining ceramic 24 is the same as that of the water retaining ceramic 20.

The inner diameter _{D 5} of the ventilation holes 25 is 5% to 90%, especially 10 to 60% of the diameter _{D 4} of the water retention ceramics 24 are preferred.

  The distance between the vent holes 25 is preferably about 2 to 100 mm, particularly about 6 to 30 mm.

  The distance between the upper end surface or the lower end surface of the water retaining ceramic 20 and the nearest vent hole 25 is preferably about 2 to 100 mm, particularly about 6 to 30 mm.

  In FIG. 3, the vent holes 25 are parallel to each other, but a plurality of vent holes 27 having different installation heights may be provided with different directing directions, like the water retention ceramic 26 of FIG. . The preferred diameter and height of the water retention ceramic 26 of FIG. 4, the inner diameter of the air hole and its position are the same as in FIG.

  In FIGS. 3 and 4, two lateral vent holes 25 are provided, but one or three or more lateral vent holes 25 may be provided.

  When two or more vent holes 25 are provided, each directing direction is arbitrary. The vent hole 25 may extend in a direction oblique to the column axis. That is, the vent hole may be inclined when the column axis direction is the vertical direction.

  In the water retention ceramic according to the present invention, a vent hole 29 made of a horizontal hole crossing in a cross shape extending in the four radial directions may be provided as in the water retention ceramic 28 of FIG.

  Such radial vents may extend in three radial directions or in five or more directions.

  Further, although not shown, a vent hole extending in the column axis direction and a vent hole extending in the lateral direction or the tilt direction may be provided. For example, when the outer shape of the water retaining ceramic 20 and the outer shape of the water retaining ceramic 24 are the same, the vent hole having the same shape as the vent hole 21 provided in the water retaining ceramic 20 is used as the column axis of the water retaining ceramic 24. You may provide so that a part may be penetrated to a column-axis direction. Further, when the outer shape of the water retaining ceramic 20 and the outer shape of the water retaining ceramic 24 are the same, the vent hole having the same shape as the vent hole 21 provided in the water retaining ceramic 20 is provided as the column axis of the water retaining ceramic 26. You may provide so that a part may be penetrated to a column-axis direction.

  In the above embodiment, the water retention ceramics are all cylindrical, but they may be elliptical, triangular, pentagonal or higher polygonal. Further, the shape may be other than a column shape, for example, a spherical shape, an elliptical spherical shape, a cube shape, a cone shape, a disk shape, or the like.

  In the case of a water retention ceramic having a shape other than a cylindrical shape, the volume is preferably approximately the same as that of the cylindrical water retention ceramic.

[Water retention structure]
Next, the water retention structure of the present invention will be described.

  This water retaining structure is obtained by distributing the water retaining ceramic of the present invention to a building or the ground.

  Among the buildings, it is preferable to distribute ceramics for water retention on the roof. Water-retaining ceramics may be distributed directly on the building or on the ground surface. A ventilation plate is installed with a space between the top surface of the building and the ground surface, and the water-retaining ceramic is distributed on the ventilation plate. May be. In this way, since air flows in the space below the ventilation plate, water vapor evaporates from the lower side of the water retaining ceramic, and the cooling effect is improved.

  FIG. 6 is a longitudinal sectional view showing an example of this water retaining structure, and a ventilation plate 42 is installed above a building or the ground surface 40 via a spacer 41. A ventilation space 43 is provided below the ventilation plate 42. The installation height of the ventilation plate 42 is preferably about 1 to 300 mm, particularly about 5 to 150 mm.

  As the ventilation plate 42, various kinds of materials such as a punching metal, a net-like body, a grating, and a saw-like member can be used. A beam may be installed between the spacers 41, and the ventilation plate 42 may be installed thereon.

  Ceramics for water retention may be randomly spread on the ventilation plate 42 or may be regularly arranged.

  In FIG. 6, the water retention ceramics 24 shown in FIG. 3 are arranged so that the column axis direction of the water retention ceramics 24 is the vertical direction. Further, the side surfaces of the water retaining ceramics 24 are butted closely so that the air holes 25 of the water retaining ceramics 24 are aligned in a straight line. By communicating the air holes 25 in this way, water evaporated from the respective water retaining ceramics 24 into the air holes 25 smoothly flows out of the water retaining structure, thereby improving the cooling effect.

  In FIG. 6, only one stage of the water retaining ceramic 24 is provided on the ventilation plate 42, but two or more stages may be provided. Water retaining ceramics 24, 26 and 28 other than those shown in FIG. 3 may be used.

  According to this water retaining structure, water can be sufficiently retained even when a sudden rainfall or a large amount of water is temporarily sprinkled. Therefore, it is also possible to prevent urban flooding by spreading water retaining ceramics in many buildings, gardens, open spaces, etc. in the city.

  In addition, since the water retaining ceramic is cooled by the latent heat of evaporation when water evaporates, it is possible to prevent the heat island phenomenon by spreading the water retaining ceramic in many buildings, gardens, open spaces, etc. in the city. It becomes.

  Next, the preferable pore diameter, material, composition, production method and the like of the porous ceramic constituting the water retention ceramic will be described.

[Pore diameter of ceramic for water retention]
The water-retaining ceramic used in the present invention is 53 to 70%, preferably 55 to 68% of the total volume of the water-retaining ceramic (not including the volume of the air holes), and the pore diameter is 1 to 100 μm, preferably 15 to It is preferably composed of 40 μm fine pores. As described above, by containing a large amount of such fine pores, the water retention and water evaporation properties of the water retention ceramic are improved.

This pore size 1~100μm pores of more than 60%, for example 70% to 95% pore sizes 10 to 50 [mu] m, preferably consists of pores of 15-40 [mu] m.
In particular, the water retention ceramic used in the present invention is preferably 10 to 70%, particularly 15 to 50% of the total volume of the water retention ceramic is composed of fine pores having a pore diameter of 15 to 40 μm.

The total porosity of the water retention for ceramics, Ru 55-80% der. If the total porosity of the water retaining ceramic is less than 55%, 53 to 70% of the total volume cannot be realized as the water retaining ceramic with fine pores of 1 to 100 μm, and if it is larger than 80%, the strength is insufficient. The practicality as a laying material is impaired.

  In the present invention, the pore diameter is measured according to JIS R 1655 using a mercury porosimeter.

  The water in the pores having the above pore diameter is easily pushed out of the water retaining ceramic during freezing, and the water retaining ceramic is hardly cracked even when subjected to repeated freezing and thawing action.

[Composition of ceramics]
The composition of the ceramic constituting this ceramic for water retention is SiO ₂ : 50 to 80 wt%, preferably 55 to 70 wt%.
Al ₂ O _3: 10~30wt% preferably 15-25 wt%
Total Na ₂ O and _{K 2} O: _1~10wt% preferably 3～7Wt%
Der Ru.

  Such aluminosilicate ceramics containing a large amount of soda and potash are hydrophilic, and the water retention and water evaporation properties of the water retention ceramic are good.

  In order to prevent algae from being generated in the water retaining ceramic in a wet state, CuO may be mixed in the water retaining ceramic in an amount of about 0.1 to 1.5 wt%.

  The water retention ceramic used in the present invention may be provided with a photocatalyst effect by applying a photocatalyst coating liquid to a part or the entire surface thereof, thereby improving the contamination resistance of the water retention ceramic by the purification action by the photocatalyst. be able to.

[Production method of ceramic for water retention]
Next, the suitable manufacturing method of the ceramic for water retention is demonstrated.

In order to produce this water-retaining ceramic, ceramic raw materials, alumina cement and powdered water-absorbing polymer and preferably further lithium carbonate are dry-mixed, then water is added and mixed, followed by molding, drying and firing. . The blending ratio at this time is preferably
Ceramic materials: 75-95 wt%, especially 80-95 wt%
Alumina cement: 3-15 wt%, especially 5-15 wt%
Water-absorbing polymer: 0.5 to 10 wt%, especially 1 to 5 wt%
Lithium carbonate: 10 wt% or less, especially 1-10 wt%, especially 1-5 wt%
It is.

  In addition, the mixing ratio of water is about 130 to 170 wt% with respect to the total weight of all raw materials other than water, and about 80 to 150 times that of the water-absorbing polymer is easy to handle, moldability, It is preferable from the viewpoint of the water-absorbing expansibility of the water-absorbing polymer, subsequent drying, and firing efficiency.

As the ceramic material, one or more kinds of potash feldspar, clay, silica sand and the like can be used, but are not limited thereto. These ceramic materials are selected and used so that the ratio of SiO ₂ , Al ₂ O ₃ , and Na ₂ O + K ₂ O is as described above.

  As the alumina cement, those defined in JIS can be used.

  Since this alumina cement is hardened quickly, when it is mixed by adding water and molded, a molded body that can be handled in a short time is obtained.

  As the powdery water-absorbing polymer, those having a particle size of about 10 to 50 μm, particularly about 20 to 30 μm are suitable.

  As the water-absorbing polymer, one of various kinds such as polyacrylate, saponified vinyl acetate / acrylic acid ester copolymer, starch / acrylic acid graft copolymer is used alone, or two or more kinds are mixed. Can be used.

  To form this mixture, a quantitative filling machine, a cast molding machine, an extrusion molding machine, a honeycomb molding machine, or the like can be used, but the present invention is not limited to this. Examples of the method of opening the vent hole include a method of opening using a mold or the like at the time of molding. For example, in the case of extrusion molding, an inner ball is provided for molding, and a hole can be opened simultaneously with the molding. Moreover, it is possible to open a hole in the molded body after molding with a tubular mold. Moreover, a hole can also be opened using a drill with respect to a dry body or a sintered body.

  The molded body is preferably heated and dried at 80 to 250 ° C. for 5 to 40 hours, particularly 6 to 12 hours, and then preferably at 1050 to 1200 ° C., particularly 1100 to 1150 ° C. for 0.2 to 20 hours, particularly 0.3 to. Firing for 2 hours to obtain a sintered body. A roller hearth kiln, a tunnel kiln, a shuttle kiln, etc. can be used for this baking.

[Application examples and effects of ceramics for water retention]
Ceramics for water retention are porous ceramics whose pore diameter and the ratio thereof are strictly controlled, and have a performance of controlling water by absorbing rainwater and evaporating the absorbed water by solar radiation.

  Therefore, environmental measures such as A and B below can be achieved by laying the ceramic for water retention on the roof of a building, a passage of a private house or public facility, a plaza, a garden, and the like.

A. Environmental measures for individual buildings A-1. Energy-saving · CO ₂ reduction of the building:
By laying water retaining ceramics on the building roof, the roof slab temperature can be lowered and the power consumption of the air conditioner downstairs can be reduced by rainwater control and transpiration with the water retaining ceramics.

  Moreover, the ambient temperature of the air-conditioning outdoor unit installed on the roof can be lowered, the air-conditioning operation efficiency of all floors can be improved, and the amount of power used can be reduced. In particular, it is possible to greatly reduce the amount of power used for air conditioning in the summer on the rooftop floor.

As a result, CO ₂ emission can be reduced.

A-2. Alternative to rooftop greening in buildings:
Water-retaining ceramics have the same water retention and cooling performance as plants such as lawn, and are highly durable, long-life, maintenance-free materials that use natural rainfall, and are therefore promising candidates for replacing rooftop greening.

  The current rooftop greening takes time to maintain and high management costs, but the ceramics for water retention can solve this problem.

A-3. Reducing maintenance costs for building roof waterproof layers:
Since the ceramic for water retention has a low thermal conductivity of about 0.2 W / m · K and a high heat insulating property, the roof slab temperature can be kept constant by laying it on the building roof. In addition, ultraviolet rays can be prevented.

  At present, repair of the waterproof layer is required in about 10 years, but this maintenance frequency can be reduced by applying a water retaining ceramic.

B. Urban environmental measures B-1. Heat island measures:
Water-retaining ceramics can be laid under various equipment (outdoor units, heat sources, etc.) that occupy the roof of the building. By laying the water-retaining ceramics of the present invention at various locations, the transpiration area of the city can be increased and the entire city block This temperature can be further reduced.

  Moreover, since the ceramic for water retention has a high transpiration capacity compared with lawn, the temperature reduction effect per unit area is also high compared with lawn.

B-2. Guerrilla heavy rain measures:
Water-retaining ceramics have a higher flood control capability than lawn, so if they are laid on the roof of the building as much as possible, peak cuts in guerrilla heavy rain can be expected.

B-3. Reuse of resources Ceramics for water retention can be produced using feldspar glitter, which has conventionally been regarded as waste, as a main raw material (for example, 90% of the raw material). The feldspar killer is a by-product of mining the feldspar as a raw material for tiles, and was previously considered as waste.

  Below, the experiment example thru | or the trial calculation example which show the effect of said A and B by the porous ceramics which comprise said ceramics for water retention are given.

<A-1. Energy saving and CO ₂ reduction of buildings>
As shown in FIG. 11 (a), a concrete slab 12 is laid in a box-shaped container having a bottom and four side surfaces made of a heat insulating material 11, and a porous ceramic (for example, an experimental example described later) is formed thereon. The porous ceramics manufactured in the same manner as in No. 2) was laid in a thickness of 10 cm to obtain a test body 1. The laying area of the porous ceramic is 1 m ² . A temperature sensor 14 was provided between the bottom heat insulating material 11 and the concrete slab 12.

  Separately, instead of the porous ceramics, a specimen planted with lawn was used as a test specimen 2, and a specimen without porous ceramics was used as a test specimen 3.

  These specimens 1 to 3 were placed side by side, and the time-dependent changes in the temperature and the temperature measured by the temperature sensor 14 of each specimen were examined. The results are shown in FIG. 11 (b).

  In the graph of FIG. 11 (b), the water absorption period was a period when there was rainfall, and the rest was cloudy or sunny.

  As apparent from FIG. 11 (b), the test body 1 in which the porous ceramics was laid had a temperature reduction effect of -8 ° C. at the maximum under the slab relative to the test body 3 without laying. And the transpiration | evaporation effect of the test body 1 was a bigger thing than the test body 2 which planted the lawn.

  From this result, it can be seen that rainwater control and transpiration with porous ceramics can lower the roof slab temperature and reduce the amount of power used for air conditioning downstairs.

  Next, as shown in FIG. 11 (a), the surface temperature of the roof slab is measured by the test body 1 in which the porous ceramics 13 are laid and the temperature sensor 14 is provided, and the test body 3 in which the porous ceramics are not laid. As a simulation of this change, the measured temperature of the temperature sensor 14 for 24 hours a day was examined, and the results are shown in FIG.

  The general thermal conductivity of porous ceramics, concrete slabs, and soil is as shown below.

Porous ceramics: 0.20 W / m · K
Concrete slab: 0.15 W / m · K
Sat: 0.63 W / m · K

  As is apparent from FIG. 12, the daily change in the surface temperature of the roof slab is 2 ° C. in the specimen 1 in which the porous ceramic is laid, whereas it is 15 in the specimen 3 in which the porous ceramic is not laid. It was ℃. From this result, it can be seen that the thermal load on the slab caused by solar radiation is reduced by laying the porous ceramics.

Next, as shown in FIG. 13 (a), a concrete slab 12 is laid in a box-shaped container having a bottom portion and four side surfaces made of a heat insulating material 11, and a porous ceramic (for example, described later) is laid thereon. The porous ceramics manufactured in the same manner as in Experimental Example 2) was laid in a thickness of 10 cm to obtain a test specimen 4. The laying area of the porous ceramic is 1 m ² . A temperature sensor 14 was provided at a position 1 cm above the laying surface of the porous ceramic.

  Separately, the test body 5 was not laid with porous ceramics. In this test body 5, a temperature sensor 14 was provided at a position 1 cm above the concrete slab 12.

  These specimens 4 and 5 were placed side by side, and the change in temperature measured by the temperature sensor 14 for 24 hours a day was examined. The result is shown in FIG. 13 (b).

  As is clear from FIG. 13 (b), there was a difference of 5 ° C. maximum as the atmospheric temperature above 1 cm between the test body 4 laid with porous ceramics and the test body 5 not laid.

  From this result, it can be seen that by laying the porous ceramics, the ambient temperature of the air conditioner outdoor unit installed on the roof can be lowered, the operating efficiency of air conditioning on all floors can be improved, and the amount of power used can be reduced.

<A-2. Alternative to rooftop greening of buildings and A-3. Reduction in maintenance costs for roof waterproofing layer of buildings>
Per unit area when porous ceramics are laid on the roof of the building (case 1), conventional specifications without laying this (case 2), and rooftop planting with lawn or shrub (case 3) The initial cost (laying or planting cost) and the maintenance (maintenance) cost for 20 years were estimated, and the comparison results are shown in FIG.

  As shown in FIG. 14, the porous ceramics is only an initial cost, and the subsequent maintenance is almost unnecessary. On the other hand, in the case 2 of the conventional specification in which no porous ceramic is laid, maintenance costs such as repair of the waterproof layer are required, and as a result, it is equivalent to the product of the present invention.

  In the case of rooftop greening 3, in addition to the initial cost, pruning, pruning, lawn mowing, fertilization, weeding, pest control, irrigation equipment inspection, and other comprehensive inspections are in addition to the costs shown in Fig. 14. In addition, the electricity and water costs necessary for the operation for watering by irrigation equipment will be charged.

  From these results, as mentioned above, porous ceramics are equivalent to the performance of plants such as lawns in flood control and transpiration, and are also highly durable, long-life and do not require maintenance management using natural rainfall. Compared with rooftop greening, the initial cost is ½ and the maintenance cost is much cheaper, which makes it a good candidate for rooftop greening alternative.

<B-1. Heat island measures>
By laying porous ceramics on the entire roof of the building in Tokyo's 23 wards, the transpiration area of a city that functions for flood control and transpiration can be increased by 10%.

  Currently, equipment (outdoor units, heat sources, etc.) is installed on the roof of the building, but porous ceramics can be laid under various equipment on the building roof, increasing the transpiration area of the city and increasing the entire city block The temperature can be greatly reduced.

  As can be seen from Fig. 16 which shows the results of repeated tests of water control and transpiration of porous ceramics and lawn, porous ceramics have a transpiration capacity approximately twice that of lawn. This increase in the transpiration area of the city is doubled by 20% if replaced with lawn, and further effectiveness is clear.

<B-2 guerrilla heavy rain measures>
Regarding porous ceramics and lawn, as is clear from FIG. 15 which compares the total amount of transpiration and water absorption per unit volume over a period of 15 days from October 2 to October 16, porous ceramics are lawn. More than twice the amount of water absorption and transpiration.

The building roof may be porous ceramics can lay to the 1.8 million ^{m 3} things flood an area of 50 km ² with a thickness of 10 cm, achieving peak cut guerrilla downpour of 3 mm / hr at 23 wards of Tokyo.

<B-3. Reuse of resources>
The porous ceramics can be produced, for example, with 90% by weight of feldspar glitter, which has been conventionally regarded as waste, and 10% by weight of other materials. When the weight of the porous ceramics per unit area is 40 kg / m ² , the amount of feldspar glitter necessary for laying 5000 m ² is
5000 (m ² ) × 40 (kg / m ² ) × 0.9 ÷ 1000 = 180 ton
It becomes.

That is, when producing 5000 m ² per day as the laying area of the porous ceramic, the necessary waste (feldspar killer) raw material is 180 tons / day, and the effective utilization effect of the waste is extremely large.

  Hereinafter, the experimental result which shows that the porous ceramic of the said mixing | blending is excellent in water retention and transpiration | evaporation property is demonstrated. The following Experimental Examples 1 to 5 are porous ceramics using the preferred composition of the present invention, and Experimental Examples 6 to 10 are porous ceramics having other compositions.

  The raw materials used in the following experimental examples are as follows.

Potassium feldspar: Nagasaki No. 8 from Seto, Aichi Pref. Silica: Katsuno Ceramics Nagasaki Kira: Nagao from Seto, Aichi Water-absorbing polymer: Sanyo Kasei Co., Ltd.
(Under 20 μm particle size by sieve (water-absorbing polymer A), particle size
20-50 μm (water-absorbing polymer B), particle size 50-100 μm
Classification into (water-absorbing polymer C). )
Alumina cement: manufactured by Lafarge Co., Ltd. Lithium carbonate: reagent grade CuO: reagent grade

[Experimental Examples 1 to 10]
Raw materials other than water were weighed in the proportions shown in Table 1, and mixed with a mixer (Nauta mixer manufactured by Hosokawa Micron Corporation) in a dry manner. Subsequently, water was added to the mixed powder in the ratio shown in Table 1 and kneaded. This was formed into a substantially disk shape having a diameter of 70 mm and a maximum thickness of 15 mm, and dried at 80 ° C. for 24 hours. A vent having a diameter of 10 mm was opened in the thickness direction using a drill on the dried molded body. This was fired in a roller hearth kiln (maximum firing temperature as shown in Table 1. Furnace passage time was 60 minutes) to produce porous ceramics.

  Each porous ceramic was subjected to component analysis and characteristic measurement. The results are shown in Tables 1 and 2.

  The porosity (excluding the volume of the vent) was measured using a mercury porosimeter (manufactured by Quantachrome). The pore diameter distribution of the pores is shown in FIGS.

  The water retention amount was measured as follows.

The porous ceramic is dried at 105 ° C., allowed to cool, and weighed to determine the weight (W ₁ ). Next, after being immersed in water at 20 ° C. for 24 hours, it is pulled up and the surface water is wiped off with a damp cloth to make it saturated. This sample is weighed to determine the weight (W ₂ ). In addition, this saturated porous ceramic is put into water in a graduated cylinder, and the volume (V) is obtained. The water retention amount (g / cm ³ ) is calculated by (W ₂ −W ₁ ) / V.

  The strength was measured by making a 10 cm × 10 cm × 0.5 cm sample by a three-point bending test (JT Toshi Co., Ltd., 50 kN digital bending tester).

  Freezing and thawing performance is the degree of damage by repeating the freezing and thawing cycle in which the saturated porous ceramic is frozen by holding at −20 ° C. for 75 minutes and then holding and melting at 30 ° C. for 90 minutes for 200 cycles. It was examined by observing and evaluated as very good (◎), good (○), slightly bad (△), and bad (x).

The transpiration performance is as follows. Place dry porous ceramics in a flat container with 5 mm of water and let it absorb water for 30 minutes, then pull it up. Ask. About the volume, the volume at the time of measuring the water retention amount is used. The water absorption amount (g / cm ³ ) for 30 minutes is defined as the transpiration performance.

  The transpiration effect duration was the duration of the cooling effect due to the latent heat of evaporation, and was measured as follows.

  As shown in FIG. 8, a square-shaped frame 2 made of a foamed polystyrene plate having a thickness of 100 mm is placed on a pallet 1 made of recycled polypropylene resin having a thickness of 150 mm to form a container. One side of this container is 1000 mm and the depth is 830 mm. Aluminum foil is stretched on the outer peripheral surface of the container.

In this container, the polystyrene foam plate 3 is spread over to a thickness of 500 mm, and the temperature sensors T _{1 to} T ₅ are arranged at five locations on the upper surface thereof.

  A concrete plate 4 having a thickness of 180 mm and a specific gravity of 2.2 is placed on the polystyrene foam plate 3. 50 kg of saturated porous ceramics 5 (shown only in FIG. 8 (b)) is deposited on the concrete plate 4. The deposition thickness is about 10 cm. The above work is performed indoors at an air temperature of 20 ° C. and a humidity of 60% RH. This container is left in a constant temperature and humidity chamber at 35 ° C. and 60% RH, and the number of days until the temperature detected by the temperature sensor rises to 35 ° C. is measured. This is the number of days for which the transpiration effect lasts.

  Further, in order to investigate the water absorption of the porous ceramics obtained in each experimental example, five porous ceramics 51 to 55 were prepared as shown in FIG. Then, the bottom porous ceramic 55 is stacked in five steps so that it is immersed in water by about 1 mm from the bottom, and left in this state for 1 hour. The water absorption rate of the ceramic 51 (the ratio of the weight of water absorbed to the weight of the porous ceramic before water absorption) was calculated.

[Discussion]
As shown in Table 1, the porous ceramics of Experimental Examples 1 to 5 having the above-mentioned preferred compositions are excellent in evaporation performance and evaporation effect duration days, and are excellent in freeze-thaw resistance and water absorption.

  On the other hand, Experimental Example 6 out of Experimental Examples 6 to 10, which do not belong to the above preferred composition, is inferior in evaporation performance, evaporation effect duration and water absorption because the pore diameter is excessive.

  Experimental Example 7 is inferior in freeze-thaw performance and water absorption because the pore diameter is excessively small.

  Since Experimental Example 8 has an excessively high porosity of 80%, it is inferior in freeze-thaw performance and water absorption.

  Since Experimental Examples 9 and 10 have a low water retention amount, the evaporation effect duration days are short and the water absorption is also poor.

DESCRIPTION OF SYMBOLS 1,50 Pallet 2 Enclosure 3 Styrofoam board 4 Concrete board 5,13,51,52,53,54,55 Porous ceramic 11 Heat insulating material 12 Concrete slab 14 Temperature sensor 20, 22, 24, 26, 28 Ceramic for water retention 21, 23, 25, 27, 29 Ventilation hole 40 Ground surface or building 41 Spacer 42 Ventilation plate 43 Ventilation space

Claims (11)

In ceramics for water retention made of sintered porous ceramics,
The composition of the ceramic constituting the-holding water for _{ceramics, SiO 2: 50~80wt%, Al} 2 O 3: 10~30wt%, the sum 110 wt.% Of Na ₂ O and _{K 2} O,
It has a vent hole with an inner diameter of 1 mm or more,
The total porosity of the water retaining ceramic (the porosity does not include the volume of the vent) is 55 to 80 wt%, and 53 to 70% of the total volume of the water retaining ceramic is composed of pores having a pore diameter of 1 to 100 μm. 60% or more of the pores having a pore diameter of 1 to 100 μm are pores having a pore diameter of 10 to 50 μm.   2. The ceramic for water retention according to claim 1, wherein a plurality of the air holes are provided substantially in parallel.   2. The ceramic for water retention according to claim 1, wherein vent holes extending in different directions are provided.   4. The ceramic for water retention according to claim 3, wherein at least some of the vent holes having different extending directions intersect each other.   5. The ceramic for water retention according to claim 1, wherein the ceramic for water retention has a column shape extending in a column axis direction, and the vent hole extends in a column axis direction. 6. .   The water retention ceramic according to any one of claims 1 to 4, wherein the ceramic for water retention has a column shape extending in a column axis direction, and the vent hole extends in a direction intersecting with the column axis direction. Ceramics for water retention.   A water retention structure comprising the ceramic for water retention according to any one of claims 1 to 6 distributed on a building or a ground surface.   8. The water retention structure according to claim 7, wherein at least a part of the vent holes are directed in a vertical direction.   8. The water retention structure according to claim 7, wherein at least some of the vent holes are oriented in a lateral direction.   10. The water retention structure according to claim 9, wherein the water retention ceramics are arranged so that the plurality of water retention ceramic vents are connected in a straight line.   The ventilation plate according to any one of claims 8 to 10, wherein a ventilation plate is arranged with a ventilation gap between the building and the ground surface, and the water-retaining ceramic is distributed on the ventilation plate. Water retaining structure.

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