JP2018062455A - Water retentive block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water retentive block having improved water absorption performance and ensuring to have adequate water absorption performance.SOLUTION: The present invention provides the water retentive block in which 90% or more of the cavities storing water is composed of capillary tubes having a diameter of 10 μm or less, and the block has a water retention amount of 0.25 g/cmor more and a water absorption amount of 3 mm or more measured by a capillary tube water absorption test. The test is carried out by using a capillary tube water absorption testing device in which: a lower container 1 having water and an upper container 2 having a sand layer of 30 mm thick are arranged vertically; both containers have a larger surface area than a bottom surface of a water retentive block for which water absorption from the sand layer 4 is measured; the block is placed on the upper container 2; an absorption band made of cotton 5 passing through a slit opened on the bottom surface of the upper container 2 connects a lower portion of the sand layer 4 in the upper container 2 and the water in the lower container 1 to suck up and send the water in the lower container 1 into the sand layer 4; and the block absorbs water supplied by capillary tube water absorption through the sand layer 4. The water absorption amount is determined as the amount of water absorbed by the block for 30 minutes after the start of the absorption from the sand layer which is measured in terms of increased weight of the block.SELECTED DRAWING: Figure 2

Description

    The present invention relates to a water retention block such as a high water absorption, high water retention interlocking block (hereinafter abbreviated as ILB), a ceramic block, a floor plate, and the like that absorbs water in laid sand.

Conventionally, water retention blocks aim to contribute to prevention of urban heat island phenomenon by lowering the temperature of the pavement surface by evaporating the water stored in the block body through the block surface, but existing water retention concrete blocks There is little water storage in the block body. ILB standard 0.15 g / cm ³ or more, typically ^{0.15g / cm 3 ~0.22g / cm 3} , the case of 0.15 g / cm ³ 60 mm thick block with 9 mm (indication of the amount not the length, the rainfall The same, the same applies hereinafter), and in summer clear weather, about 5 mm / day evaporates. Therefore, the evaporation duration is short. Furthermore, because the capillaries in the main body are thick, the suction speed of the water below the block (water that holds sand, crushed stones, etc.) is slower than the evaporation rate in summer, and the capillaries are thick, so the surface layer part is easily dried. The evaporation surface falls immediately below the surface, and in both cases, the surface temperature reduction effect does not last long (evaporation on the surface has the effect of lowering the surface temperature most. If the evaporation surface is lowered by 5 mm or more, the effect is 1) Drastically reduced to / 4 or less). From the above, the water-reducing performance from the sand is especially low, so the temperature-reducing effect of existing water-retaining concrete blocks is about a day after rain. Therefore, it is not only popularized, but at present, the effect will not continue unless there is always an artificial supply of water.

Therefore, the inventors have developed a fired block using the unused resource glitter, which is a fine powder having a median diameter of 20 μm, in order to further improve the water retention amount. The fine powder fired product forms a large number of thin capillaries in the main body, has a large water storage capacity, and has a water retention amount of 0.20 to 0.25 g / cm ³ . The thin capillary tube not only retains water but also absorbs water on the ground side, such as laying sand provided for laying (water tends to move from the thicker side of the capillary to the thinner side, usually the sand on the ground side, The crushed capillaries are thicker than this developed product). Since the water in the block body and the water on the ground side can be used together, evaporation on the surface lasts for a long time. If the water retention amount is 0.25 g / cm ³ and the block thickness is 60 mm, the main body is 15 mm and the sand retention amount is about 0.3 g / cm ^3. There is 9mm water storage. In addition, the crushed stone under the laying sand can retain water of 0.15 g / cm ³ if it is a particle size-adjusted crushed stone, and if it is a sidewalk, it is laid 10 cm thick. Therefore, 15 mm of water can be stored in this part. . Therefore, a total of 39 mm of water can be stored immediately after rainfall. The pavement surface where this block was laid using appropriate crushed stones and laid sand, the block surface remains moist even in the summer and after four days of fine weather after raining, it becomes a normal ceramic block that does not retain water. In comparison, the surface temperature is low at 12 to 7 degrees in midday when the sunlight is strong (surface temperature difference from the non-absorbing block = temperature reduction effect). This is a great effect in itself, but after 5 days, the effect decreases rapidly. This effect must last longer.

    In the evaluation of water retention, the water retention ILB is JIS A 5371 (Non-Patent Document 1), and the water retention amount is defined as water retention, and the suction height after 30 minutes is defined as water absorption. The water retention amount is obtained by immersing the block in water for 24 hours and dividing the water absorption amount by volume, and the standard is 0.15 g / cm 3 or more. The sucking height after 30 minutes. It is stipulated that the amount of water absorbed for 30 minutes from the bottom of the block is 70% or more of the amount of water retained, and the water absorption speed is required to be a certain level or higher. All of the water is in a free state (gravity is applied, but there is no restriction of capillaries, etc.).

  The water retention block is evaluated by measuring the surface temperature of the laid block in the summer and calculated by the temperature difference from the non-absorbent block (= temperature reduction effect). There is no test method, and the relationship between this effect and JIS standards is unclear. Established an evaluation test method and device for determining the properties of the block in conjunction with the effects seen in this summer laying product, set the criteria for the test, and developed a block that matched it with raw material blending and manufacturing methods. This is the present invention.

In order to secure the temperature reduction effect, it is necessary to have the ability to store water, absorb and move, and evaporate, and the block must have the following properties.
(1) Water holding capacity of at least 0.25 g / cm ³ or higher, high water holding capacity (2) Water in the laid sand can also be absorbed (3) This water moves to the surface of the block, near the surface in the block The water movement speed is superior to the summer evaporation speed. (4) The evaporation amount is appropriate.
The conventional block developed by the inventor achieves a water retention amount of 0.20 to 0.25 g / cm ³ with an appropriate amount of glitter for (1). For (4), it is possible to use water repellents and glazes, but (2) to (3) differ considerably depending on the raw material composition, water absorption is fast, but fast evaporation, water absorption is slow, evaporation There is a thing with little temperature, and a thing with a large temperature reduction effect with the amount of evaporation at an appropriate speed and the amount of evaporation. This water absorption and movement is all possible due to the presence of capillaries. Therefore, since this difference seemed to be in the diameter of the capillary, the capillary phenomenon was investigated. It has been already known that the water absorption height of the capillary tube is affected by the tube diameter, and the thinner the capillary, the higher the water rises, but what happens to the movement speed of the water in the capillary tube and the movement of the interface where the different capillary diameters touch? I didn't know. Therefore, a block with a different pipe diameter was made as a prototype, and the water absorption state was examined by two methods: water absorption directly from water and water absorption from laying sand. This is a commonly performed method in which a prototype block is placed in a container filled with water at a depth of 5 to 10 mm directly from water, and the water is absorbed from the lower part of the block to check the water absorption status. As a result, the following was found.
As it has been said in the past, if the capillary diameter is large, the water will not rise high, and if the capillary is thick, the water will absorb and rise quickly, while if it is thin, the water will absorb and move slowly.
This is a case where free water (water that is not subjected to a force other than gravity) is absorbed. It is necessary to test the relationship between the pipe diameter and the water absorption when absorbing water confined by the capillary in the sand, but there is no established test method, equipment, or standard.

In view of this, the inventors have developed a firing block using the unused resource glitter, which is a fine powder, in order to further improve the water retention amount (Patent Document 1). The fine powder fired product forms a large number of thin capillaries in the main body, has a large water storage capacity, and has a water holding capacity of 0.25 g / cm ³ or more. A thin capillary tube not only retains water but also absorbs water on the ground side, such as laid sand provided for laying (water moves from the thicker side of the capillary to the thinner side, usually the ground side-laid sand and crushed stone Capillary tube is thicker than this developed product). Since the water in the block body and the water on the ground side can be used together, evaporation on the surface lasts for a long time. If the water retention amount is 0.25 g / cm ³ and the block thickness is 60 mm, the main body is 15 mm and the sand retention amount is about 0.3 g / cm ^3. There is 9mm water storage. Immediately after rainfall, 24mm water storage is possible. If the crushed stone is laid about 100 mm thick under the laying sand, and the particle size-adjusted crushed stone is used for this, the amount of stored water can be further increased. Pavement surface using this appropriate laying sand, the paved surface laying the block surface in the summer, even after four days of fine weather after rain, remains moist, compared to a ceramic block that does not retain water. The surface temperature is low (= temperature reduction effect) at 12 to 7 degrees in midday with strong solar radiation. This is a great effect in itself, but after 5 days, the effect decreases rapidly. This effect must last longer.

  In addition, as described above, a method and apparatus for evaluating the water absorption performance of a block having a high water retention amount has not been established, but the water absorption distribution in the depth direction of concrete can be evaluated nondestructively. As an example, Japanese Patent Application Laid-Open No. 2014-32126 (Patent Document 1) discloses a center chamber having a circular shape in plan view having an opening surface having the same planar position, an intermediate chamber as a first annular chamber surrounding the center chamber in an annular shape, and the An outer peripheral chamber as a second annular chamber that annularly surrounds the intermediate chamber, and a reservoir provided in each of these chambers for supplying water to each of the chambers. To detect the amount of water absorbed by the concrete in each chamber after the water is stored and supplied to each chamber It has been proposed those, but can not be applied to the water-holding block, which may be further large scale.

  JP 2014-32126 A

  JIS A 5371 Precast unreinforced concrete products

The urban summer heat island phenomenon is partly due to non-water retentive asphalt and concrete pavement, and water retentive blocks are commercially available to prevent it. In ILB, there is a standard for water retention of 0.15 g / cm ³ or more in ILB, but with this amount of water retention (for example, 0.2 g / cm ³ ), the duration of the summer temperature reduction effect is extremely short. Most commercial products have a water retention amount of 0.22 g / cm ³ or less, the water absorption from the lower part of the block laying, the sand, etc. is slow, and the temperature reduction effect is small. Accordingly, the inventor has developed a fired block using the unused resource glitter, which is a fine powder having a median diameter of 20 μm, in order to further improve the water retention amount. The pavement surface where this block was laid is 12 degrees in the midday when the sun is strong in the sun, compared to a ceramic block that does not retain water, even in the summer, when the weather continues for 4 days after raining, the block surface remains moist. To 7 degrees, the surface temperature is low (surface temperature difference from the non-absorbing block = temperature reduction effect). This is a great effect in itself, but after 5 days, the effect decreases rapidly. This effect must last longer.

  In order to reduce the temperature by evaporating from the block surface, in addition to the water retention of the block body, the water absorption capacity from the lower part of the block laying (the crushed stone and the sand in the lower part have more water than the block) It is important to secure the movement speed of the water in the block (especially the movement speed near the block surface) while water absorbs and replenishes the water lost by evaporation, and absorbs the water below the block. This ability can be solved by setting the capillary volume and capillary diameter in the block, so that the evaporation from the block continues as long as possible, and the temperature reduction effect due to water evaporation lasts long, and the urban summer heat island phenomenon I want to help prevent dryness in winter. Capillary tube setting requires a capillary water absorption test device that absorbs water from the sand, and the development and establishment of this method is required.

In the present invention, as shown in the micrograph of the water retention block of FIG. 1, 90% or more of the voids storing water in the block are capillaries having a tube diameter of 10 μm or less, and the water retention amount is 0.25 g / cm ^3. Above, the lower container containing water, which is larger than the bottom of the water retaining block for measuring water absorption from the sand, and two upper containers containing the same 30 mm thick sand are stacked, and the upper container has a block. Water is applied to the bottom sand by the water absorption band of the cotton cloth that connects the bottom sand of the upper container and the water of the lower container through a slit provided in the bottom of the upper container. Water absorption in the sand that is supplied and supplied by capillary absorption is absorbed by the block, and water absorption from the capillary water absorption test device that measures the water absorption from the sand of the block by changing the weight of the block. Amount A water retention block, characterized in that not less than mm. If it is 3 mm or more, it is desirable that water can be retained up to an allowable amount, but in reality, at least 3 mm or more is sufficient.
I want to measure water absorption from the sand. Lay sand on a box-shaped container that is larger than the bottom of the block to a thickness of 30 mm, place a block on it, and measure the amount of water absorbed from the sand, but it is necessary to preliminarily absorb the sand. If water is poured from the laying sand, water will also enter the gaps other than the capillaries, and free water will increase, so that the water bound by the laying sand capillaries will not be absorbed. Further, if the block has a large amount of water absorption, water is insufficient and the water absorption conditions are not constant. I want to supply water constantly to the sand by capillary absorption. Next to the laying sand container, place a container filled with water so that the water surface is below the bottom of the sand, connect the water and the bottom of the laying sand with a cotton towel, spread the water with capillary water absorption into the sand. A method of supplying water can be considered. With this, water can be regularly supplied to the laid sand by capillary absorption, but it is not compact, and the evaporation amount of water from the block, which will be described later, could not be measured. . Accordingly, the capillary water absorption test apparatus shown in FIGS. Capillary water absorption test device A stacks a lower container containing water, which is larger than the bottom of the water retention block for measuring water absorption, and two upper containers containing the same 30 mm-thick sand, and blocks the upper container. Place the water in the lower part of the water by the water absorption band of the cotton cloth that connects the lower part of the upper container and the water in the lower container through the slit established in the bottom of the upper container. In addition, this is a capillary water absorption amount test apparatus for measuring the water absorption amount from the block sand by changing the weight of the block by causing the block to absorb the water in the sand supplied by capillary water absorption. The outer dimensions of the containers 1 and 2 are 220 mm × 120 mm, and although not shown, two slits of 5 mm × 50 mm are provided along the side wall of the container. The amount of water in the lower container 1 is preferably 20 to 30 mm in depth in the container. Furthermore, the size of the block placed on the upper part of the spread sand is general, and is 200 mm × 100 mm × 60 mm. The spread sand is sand having a particle size of 4.75 mm or less and a 75 μm sieve passing amount of 5% or less.

With this capillary water absorption test device, the degree of water absorption from the sand was measured. As a result, graphs as shown in FIGS. 4 and 5 were obtained, and the relationship between the water absorption time and the water absorption amount became clear. The water absorption from the sand was as follows.
(1) The water absorption rate of water is much slower than that of free water, and there are some that do not slow down.
(2) Those that are slow are those with a large capillary diameter, and those that are not changed are those with a small tube diameter.
(3) The amount of water absorption does not change although there is a difference in time.
Thus, the result is not the same as from free water. If the capillary diameter of the block is large, the water absorption speed becomes slow. Of the three brands of water retaining ILB examined as a comparison, two brands were about 10% faster than water, one brand was extremely slow, and water absorption from water increased 60 mm within one hour. It took 3 days from the sand to reach it. If it is determined at 24 hours, it is a delay that is determined not to absorb water. The inventor's block is about 50% to 60% of the water absorption rate from water. Capillary water that separates the interface is easy to move from the thicker to the thinner capillary, but harder to move from the thinner to the thicker. When the block tube diameter is large, the movement of the interface becomes rate-limiting, and the water absorption speed becomes slow. If it is slow, the movement speed in the block also becomes slow. On the other hand, the water absorption speed does not change for the thin block pipe diameter even if there is an interface in contact with the sand. When the capillary is thick, the moving speed at the interface is rate-limiting. However, when the capillary is thin, the moving speed is originally slow, so the interface is not rate-limited and the speed inside the capillary is reached.
Therefore, if the quality of the block is judged based on the result of free water absorption, the result of laying will be mistaken. The type of block and the amount of water absorbed (mm) for 30 minutes after the start of water absorption are shown in the table of FIG. It can be seen that there is a difference depending on the type of block.

  FIG. 7 shows the degree of water absorption rate (water absorption amount per hour) from the spread sand. FIG. 7 shows whether the temperature reduction effect increases as the amount of evaporation increases for blocks where evaporation occurs on the block surface, except for blocks such as ILB where the tube diameter is too thick and evaporation does not occur on the surface. It has been investigated. After absorbing water by the water absorption test method shown above, the side of the block and the exposed surface of the exposed sand are covered with aluminum tape (Fig. 10). As a result of investigating the relationship between the surface temperatures of these days, it was found that when the evaporation amount was 4 mm or less, the evaporation amount affected the temperature. This is an August experiment in hot Nagoya. FIG. 7 of the experimental example is data for 5 days of three test specimens. Therefore, the amount of evaporation needs to be 4 mm or more per day, and the effect does not change even if it is evaporated more than that. The water absorption test device devised this time can also measure evaporation.

  For this reason, it is necessary that the rising speed of water from the laying sand and the amount of movement of water near the block surface have an ability to exceed the evaporation amount of 4 mm. Even if it is 4 mm per day, it evaporates mainly for 8 hours in the daytime, so when considering the amount of evaporation per hour, this point is taken into consideration and an evaporation capacity of 0.5 mm or more per hour is required. . The amount of water movement near the surface can be determined from the amount of water absorbed from the sand for 30 minutes.

That is, the amount of water moving near the block surface is such that the amount of water absorbed from the sand is a function relationship with the water absorption time, Y = aX ^1/2 (Y is the amount of water absorption, X is the water absorption time, and a is a constant by the block). As shown in FIG. 5, the amount of water absorption is proportional to the square root of the water absorption time. This is already known in the case of water absorption from water, and it has been found that the block of the inventor is also in this relationship even from the sand, so the ascending flow rate near the surface is determined from this (differentiated). Using this, the flow rate on the surface when the water absorption from the sand was 30 mm for 30 minutes was 0.6 mm / hr. Thus, it can cope with evaporation of 0.5 mm for 1 hour. If the amount of water absorption for 30 minutes from the sand is obtained, the moving speed of capillary water near the surface can be estimated. Conversely, the amount of water absorbed for 30 minutes from the sand can be obtained from the required moving speed near the surface. This can be used as a reference. If the block thickness is the same, the moving speed near the surface (surface flow rate) is proportional to the square of the water absorption amount for 30 minutes and inversely proportional to the water retention amount.

The table of FIG. 8 shows the results of the water absorption amount mm (amount) for 30 minutes measured by this test apparatus and the temperature reduction effect of the actually laid blocks. The fact that the commercially available water-retaining ceramic block in the table is 3.6 mm has almost no effect due to the fact that the water retention amount is small and the capillary diameter is large, so that the evaporation is fast. The same can be seen from the graphs of FIGS. The water retention amount is a value according to a JIS test method in which a block is placed on a water surface having a depth of 5 mm to 10 mm, and the water absorption amount for 24 hours is divided by the block volume (cm ³ ). The temperature reduction effect is the temperature difference from the non-absorbing block (block of the same shape without water absorption) by laying the block with a normal construction method, measuring the surface temperature every day after noon every day after raining in the summer. . The greater the negative value, the greater the effect.

  The amount of water absorbed for 30 minutes represents the amount of water absorbed. Therefore, along with the size of the capillary diameter, the water retention amount = capillary gap amount affects. If the tube diameter is the same, the amount of water absorption increases for 30 minutes as the number of capillaries increases. The water content of the inventor's conventional product is 0.20 to 0.25 g / cm 3, but this should be increased to 0.25 g / cm 3 or more. When the water retention amount increases, the water absorption amount for 30 minutes increases, and the flow rate of the block surface in conjunction with this increases. Even if evaporation occurs more than necessary, this can be adjusted with a surface glaze or the like, so that the temperature reduction effect can be prolonged.

From these results, in order to prolong the temperature reduction effect of the block, it was considered that the water retention amount of the block was 0.25 g / cm ³ or more and the water absorption amount mm (amount) for 30 minutes was 3 mm or more.

  In order to increase the amount of water retained and to increase the rate of water rise, the particle size of the raw material is made finer, conversely, chamotte and sand coarser than glitter are added, the firing temperature is adjusted, or molding is performed. There are methods such as adjusting the moisture content of the clay to lower the bulk density and changing the molding method. However, it has been found that if these are used to increase the rising speed, these blocks do not last long for the temperature reduction effect. This is because if the capillary diameter is increased, the water absorption from the sand becomes slower. Further, if the tube diameter is large, the evaporation speed is fast, the movement speed of water in the block cannot catch up with the evaporation amount, and the evaporation surface is retracted into the block. On the other hand, in the block where the capillary diameter is reduced by adding clay (2 μm or less) finer than the glitter, the water absorption speed is slow, but the temperature reduction effect continues. However, this also has a limit. For example, a clay-based blending block finer than Kira has a small temperature reduction effect and does not last long. This is due to the fact that even though water can be absorbed from the sand, the pipe has a small diameter and the water movement speed in the block is slow, and the amount of evaporation cannot be caught up. Thus, even if the speed of capillary water absorption in the water absorption test is too fast or too slow, the effect does not last long. If it is too early, it is difficult to use the sand water, and if it is too late, replenishment cannot catch up with evaporation. These are all due to the capillary diameter. Therefore, the capillary diameter may be within a range suitable for the temperature reduction effect, but it is not easy to measure the pipe diameter. It is necessary to consider the rules based on the properties linked to the pipe diameter.

  Although the results of water absorption from free water and water from laying sand are different, it is important to know the capillary diameter because the capillary diameter affects both. However, it is difficult to measure the capillary diameter. Although it can be seen with an electron microscope, it is only partially visible, expensive, and unusable on a daily basis. Therefore, instead of directly measuring the capillary diameter, it is conceivable that the water absorption amount for 30 minutes from the above-mentioned laid sand is set to 3 mm or more as a scale.

  As another method, a method of measuring the rate of water rising when free water is absorbed is also considered, and the relationship between this rate and the property that the capillary diameter seems to influence was observed. As a result, if water absorption from water is 5 cm to 18 cm in the first 30 minutes (here, the height to absorb water, the block is placed vertically in the longitudinal direction of the surface, and the normal height is 200 mm), the effect of temperature reduction continues for a long period of time. I understood that.

At 18cm or more, the capillaries are thick, and even if it is early from free water, the presence of the block-laying sand interface (because capillary water is difficult to move from thicker to thinner pipes), the water in the sand is absorbed. Is slow, and therefore the movement of water on the block surface is slow and the effect is small.
Below 5 cm, the capillaries are narrow, and the movement of water from the sand is not different from that of free water. This is because the moving speed in a thin capillary tube is originally slow (this is rate limiting). Since the movement of water on the block surface is slow, the effect is small.

  This makes it possible to determine which block has the effect of reducing the temperature, but it is easier and more convenient to define the block more directly by the water absorption method from the sand.

The most effective method for evaluating the temperature reduction effect of a block is to look at the surface temperature in the summer of the actually laid block, but the evaluation can only be done in the summer in one year.
Since this proved to be a measure of the amount of water absorption from the above-mentioned water or from the laid sand measured using the test apparatus of FIG. 2, the water absorption from the laid sand was further increased. Improvements were made in an increasing manner. In order to increase the water absorption amount for 30 minutes, the water retention amount is increased and the tube diameter is reduced. As a means, the conventional method of granulating and shaping the glitter is not used, but a method of using the cake discharged from the filter press as it is in the purification process of silica sand and feldspar is examined. The diameter is reduced and the cost can be reduced. This is the product developed by the inventors in the previous table, and has the effect of reducing the temperature for 10 days after the summer rain. If the capillary tube becomes too thin, the water absorption amount for 30 minutes becomes small. In such a case, it is effective to mix and adjust with chamotte or the like. About 20% is mixed in the raw material. When the amount of water absorption for 30 minutes is large, evaporation increases, so a glaze layer or the like that suppresses evaporation is provided on the surface. This makes the cost last longer.

Considering these, it is the present invention that the water retention amount of the block is 0.25 g / mm ³ or more and the water absorption mm (amount) for 30 minutes is 3 mm or more.

As apparent from the above ^description, in the conventional block of the inventors of the water retention capacity of ^{0.20g / cm 3 ~0.25g / cm 3} , the temperature reduction effect lasts 4-5 days, then the effect is Decreases rapidly. In order to solve this, in the present invention, 90% or more of the voids of the block are capillaries having a tube diameter of 10 μm or less, and the water retention amount of the block that has absorbed water from the spread sand is 0.25 g / cm ³ or more and 30 minutes. As a result of water absorption amount mm (quantity) of 3 mm or more, the movement speed of water in the block is superior to the evaporation rate, the amount of stored water is increased, and the water absorption performance of the water below the laying sand is increased. Even if there is a layer, the temperature reduction effect is sufficient. The effect is shown in Fig. 9 in an experiment example in the summer of 2016 as compared with the conventional product, and if it is a conventional water-retaining concrete product, the effect is lost on the second day (in this experiment, The effect of the conventional block invented by the inventor is reduced after 7 days, but the effect continues for about 10 days (glazed moist paper in the figure). It is a measurement after 34 mm of rain. It can be seen that the performance is improved and the effect can be prolonged by 2 to 4 days. The effect of the glazed block lasts for a long time because water evaporates through the glazed surface (having pores through which water vapor passes), but the amount of evaporation is suppressed. The glazed surface also has an effect of preventing dirt. At present, there is no other block that has a temperature reduction effect even after rain for 10 days without artificial water supply.

  In addition, it was found that the water movement speed near the block surface can be estimated from the water absorption amount for 30 minutes after the start of water absorption from the spread sand, in order to obtain the required movement speed near the surface from the evaporation amount in summer. The required amount of water absorption for 30 minutes after the start of water absorption from the spread sand can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the present invention, as shown in the micrograph of the water retention block of FIG. 1, 90% or more of the voids storing water in the block are capillaries having a tube diameter of 10 μm or less, and the water retention amount is 0.25 g / cm ^3. Above, the lower container containing water, which is larger than the bottom of the water retaining block for measuring water absorption from the sand, and two upper containers containing the same 30 mm thick sand are stacked, and the upper container has a block. Water is applied to the bottom sand by the water absorption band of the cotton cloth that connects the bottom sand of the upper container and the water of the lower container through a slit provided in the bottom of the upper container. Water absorption in the sand that is supplied and supplied by capillary absorption is absorbed by the block, and water absorption from the capillary water absorption test device that measures the water absorption from the sand of the block by changing the weight of the block. Amount A water retention block, characterized in that not less than mm. If the amount of water absorption for 30 minutes is less than 3 mm, the desired effect cannot be obtained. If the amount of water absorption for 30 minutes greatly exceeds 3 mm or more, the moving speed of water and the amount of evaporation increase and the effect increases, but it is necessary. The above evaporation amount is not necessary (FIG. 7), and the adjustment is necessary for the effect to last long. If a water absorption of 3 mm or more can be achieved for at least 30 minutes, a temperature reduction effect can be obtained. In the figure, singles 1, 24, and 39 are block types.
In order to obtain a block with this performance, the cake-shaped glitter that is discharged from the filter press at the time of refining ceramic raw materials is used as it is, and if necessary, clay, sand and chamotte are blended and molded. Then, it is glazed and fired at a firing temperature such that a predetermined void amount is obtained.

  The water-retaining block according to claim 1, wherein a spotted glaze layer having a thickness of 1 mm or less that allows water vapor to pass through is provided on the surface of the water-retaining block, for suppressing evaporation of the water-retaining block and improving aesthetics. is there.

  It is necessary to test the water absorption state of water confined to the capillaries in the sand. The apparatus used as this test method will be described with reference to the perspective view of FIG. 2 and the configuration diagram of FIG. 3. The capillary water absorption test apparatus A used in the present invention has two containers 1 larger than the bottom surface of the water retention block for measuring water absorption. 2 is composed of a lower container 1 containing water 3 and an upper container 2 containing 30 mm thick sand 4, a block is placed on the upper container 2, and the lower water 3 is added to the upper container 2. The bottom of the sand 4 of the upper container 2 and the lower part through the slits opened on the bottom surface of the container (in the configuration diagram of FIG. 3, the right side of the cloth connects the sand of the upper container 2 to the water 3 of the lower container 1) By means of a change in the weight of the water-retaining block, water is absorbed into the sand by the water absorption zone 5 of the cotton fabric that connects the water 3 of the container 1 and water is absorbed in the sand 4 supplied by capillary water absorption. Hair from laying sand to measure Tube is a water testing apparatus. Here, the spread sand is sand having a particle size of 4.75 mm or less and a 75 μm sieve passing amount of 5% or less.

  The present invention is used in an industry for producing a water retaining block with extremely high water retention.

  It is a microscope picture of the water retention block of this invention.   It is a perspective view which shows the structure for implementing this invention.   It is a structure sectional view showing capillary water absorption measurement of the water retention block of the present invention.   It is a graph which shows the water absorption time and amount of water absorption from the spread sand measured with the apparatus of this invention.   It is a graph which shows the square root of the water absorption time from the spreading sand measured by the apparatus of this invention, and the amount of water absorption.   It is a table | surface of the kind of the implementation block explaining this invention, and the amount of water absorption (mm) for 30 minutes after a water absorption start.   It is a graph which shows the evaporation amount and surface temperature of the Example explaining this invention.   It is a table | surface which shows the amount of water absorption of 30 minutes and the temperature reduction effect of the Example explaining this invention.   It is a graph which shows the kind of block and temperature reduction effect by the field test of the Example explaining this invention. In the figure, “moist page” is a product name of a block developed by the inventor.   It is a structure sectional view in case this invention is used for evaporation amount measurement.

A Capillary water absorption test device 1 Lower container 2 Upper container 3 Water 4 Laying sand 5 Water absorption zone (cloth)

Claims (3)

90% or more of the voids for storing water in the block are capillaries with a tube diameter of 10 μm or less, the water retention amount is 0.25 g / cm ³ or more, and the water is larger than the bottom surface of the water retention block for measuring water absorption from the spread sand. Stack the lower container containing the two upper containers with the same 30mm thick sand, place a block on the upper container, and put the water in the lower part through the slit established on the bottom of the upper container. In addition, the water absorption band of cotton cloth that connects the lower sand of the upper container and the underwater of the lower container supplies water to the sand and also absorbs the water in the sand supplied by capillary water absorption to the block. A water retention block characterized in that the water absorption amount for 30 minutes from the start of water absorption by a capillary water absorption amount test apparatus that measures the water absorption amount from the sand of the block by changing the weight of the block is 3 mm or more.   The water retention block according to claim 1, wherein a glaze layer having a thickness of 1 mm or less having pores through which water vapor passes is provided on the surface of the water retention block.   The water retention block according to claim 1, wherein a spotted glaze layer having a thickness of 1 mm or less through which water vapor passes is provided on the surface of the water retention block.