JP4390767B2 - Clay ground subsoil material and clay ground construction method - Google Patents

Description

  The present invention relates to a clay ground underlayer material capable of suppressing the generation of dust in the clay ground and a construction method thereof.

Conventionally, as a means for suppressing the generation of dust in a clay ground, a method has been adopted in which inorganic salts having hygroscopicity and deliquescence such as calcium chloride, magnesium chloride, or bitter juice are sprayed on topsoil (for example, patent documents). 1).
Japanese Patent Publication No.8-9847

  However, inorganic salts such as calcium chloride, magnesium chloride, or bitter juice run away every time it rains or sprinkles, so it is necessary to spray them repeatedly, and there is a problem that it is very expensive to maintain and manage. It was.

  In addition, the above-mentioned salts dissolved in water promote oxidation (rust generation) of iron playground equipment, benches, goals, fences, etc. installed on the ground, so that the service life of these equipment and facilities is shortened. It was a problem from the viewpoint of safety management.

In addition, if salts that flowed out from the ground flow into rivers or groundwater, they may act as environmental pollutants, and there is a concern that they may become a social problem in the future.
Against this backdrop, the present inventor has conducted intensive studies on a new technology for suppressing the generation of dust, not limited to the conventional topsoil treatment technology of spraying hygroscopic and deliquescent inorganic salts onto the ground topsoil. It was. As a result, by improving the ground subsoil using a new soil material prepared from a specific raw material, it is possible to guarantee moisture retention of the topsoil by supplying water from the subsoil and to suppress the generation of sand dust I found.

  This invention is completed based on the said knowledge, The objective is to provide the lower earth material for clay ground which can suppress generation | occurrence | production of the dust in a clay ground, and its construction method.

The characteristic configuration employed in the present invention will be described below.
The subsoil material for clay ground according to claim 1 is “pulverizing and sieving a water purification cake obtained by pressurizing, dewatering, or sun-drying a precipitate generated in a water treatment process at a water purification plant. According to the above, with respect to the water-purified cake powder having a particle size of 3 cm or less, any one or more selected from “activated carbon, zeolite, bentonite, clinker ash, perlite, and vermiculite” The water content per unit weight that can be held against gravity is greater than that of the water-purified cake powder particles ” It is characterized in that the blending amount of the high water retention capacity material is adjusted so that the CBR value (Carifornia Bearing Ratio) exceeds the design CBR value of 3.

The lower earth material for clay ground according to claim 2 is “pulverizing and sieving a water purification cake obtained by pressurizing and dewatering a precipitate generated in a water treatment process at a water purification plant or drying in the sun. By the above, “starch-based biodegradable superabsorbent resin, cellulose-based biodegradable superabsorbent resin, chitin-based biodegradable high Water-absorbing resin, polyamino acid-based biodegradable superabsorbent resin, polyacrylic acid-based non-biodegradable synthetic superabsorbent resin, polyvinyl alcohol-based non-biodegradable synthetic super-absorbent resin, polyacrylamide-based non-biodegradable synthetic It consists of a superabsorbent resin or a polyoxyethylene non-biodegradable synthetic superabsorbent resin, and any one or a mixture of two or more selected from water, and the water contained in the resin structure is not separated by gravity. Material The water content per unit weight that can be included is mixed with a high water absorption material that is larger than that of the water purification cake powder, and the amount of the high water absorption material to the water purification cake powder is determined. The CBR value (Carifornia Bearing Ratio) is adjusted so as to exceed the design CBR value 3 .

The subsoil material for clay ground according to claim 3 is "pulverizing and sieving a water purification cake obtained by pressurizing and dewatering a precipitate generated in a water treatment process at a water purification plant or drying in the sun. According to the above, with respect to the water-purified cake powder having a particle size of 3 cm or less, any one or more selected from “activated carbon, zeolite, bentonite, clinker ash, perlite, and vermiculite” A water-retaining material having a water content per unit weight that is greater than that of the water-purified cake powder particles, and “starch-based biodegradable superabsorbent resin, cellulose” Biodegradable superabsorbent resin, chitin biodegradable superabsorbent resin, polyamino acid biodegradable superabsorbent resin, polyacrylic acid non-biodegradable synthetic superabsorbent resin, polyvinyl Any one or two selected from a rucol-based non-biodegradable synthetic superabsorbent resin, a polyacrylamide-based non-biodegradable synthetic super-absorbent resin, and a polyoxyethylene-based non-biodegradable synthetic superabsorbent resin It is a material that consists of a mixture of seeds or more and does not release the water contained in the resin structure by gravity, and the water content per unit weight that can be contained is higher than that of the purified water cake powder. CBR value (Carifornia Bearing Ratio) is the design CBR value for the blending amount of the high water retention capacity material and the high water absorption capacity material to the water purification cake powder. It is characterized by being prepared to exceed 3.
Moreover, the lower earth material for clay ground according to claim 4 is the lower earth material for clay ground according to claim 2 or 3, wherein the high water absorption material is a starch-based biodegradable high water absorbent resin. A material comprising any one or a mixture of two or more selected from cellulose biodegradable superabsorbent resin, chitin biodegradable superabsorbent resin, and polyamino acid biodegradable superabsorbent resin It is characterized by being.

Furthermore, the clay ground construction method of the present invention is characterized in that the clay soil ground clay material according to any one of claims 1 to 4 is expanded , and ground surface soil is spread on the ground material to level the ground . .

  The lower ground material for clay ground of the present invention configured as described above has a higher water retention capacity than the water purification cake powder, and the water retention capacity of the water purification cake powder and the water purification cake powder. By mixing at least one of the high water-absorbing materials with high water-absorbing capacity, the water as retained by the lower soil is grounded by the action of raising the capillary while ensuring the same function as the lower soil material for the clay ground. It is characterized by being able to supply topsoil.

  The water purification cake, which is the raw material for the water purification cake powder, is a product of pressure, dewatered or sun-dried precipitates generated during the water treatment process at a water purification plant, and is generally disposed of as industrial waste. ing. In the present invention, the water-purified cake is pulverized and sieved and used as a powder particle having a particle size of 3 cm or less.

  Capillary water can be raised from the lower soil material to the ground surface soil simply by overlaying the ground surface soil and the lower soil material, but a non-woven fabric having water absorption capability may be sandwiched between the ground surface soil and the lower soil material. Thereby, the capillary rise can be performed uniformly and rapidly.

In the present invention, the high water retention capacity material means a material in which the amount of water that the material can hold against gravity (the amount of water per unit weight) is larger than that of the purified water cake powder. In the case of an inorganic substance, the porosity and the size of the void are important factors that determine the water retention capacity. On the other hand, in the present invention, the high water-absorbency materials, include water in the structure as the polymer resin, the aqueous a material that never let the force of gravity, the water content (= water content per unit weight ) Means a material that is larger than the purified cake powder.

The high water retention capability materials and high water-absorbency materials, as long as materials having the respective functions, it is possible to use various substances. If a specific example is given, for example, various highly porous materials having fine voids can be used as the high water retention capacity material. More specifically, activated carbon, zeolite, bentonite, clinker ash, perlite, Use inorganic porous materials such as vermiculite.

As the high water-absorbency materials, starch-based biodegradable superabsorbent polymers, cellulosic biodegradable superabsorbent polymers, chitin-based biodegradable superabsorbent polymers, polyamino acid-based biodegradable superabsorbent polymer, Polyacrylic acid-based non-biodegradable synthetic superabsorbent resin, polyvinyl alcohol-based non-biodegradable synthetic super-absorbent resin, polyacrylamide-based non-biodegradable synthetic super-absorbent resin, and polyoxyethylene-based non-biodegradable synthetic Use highly water-absorbing resin.

These high water retention capacity materials and high water-absorbency materials can be used alone or in combination depending on the purpose. In addition, as the high water retention capacity material that can be used in the present invention, for example, industrial waste such as ALC (Autoclaved Lightweight Aerated Concrete) powder and industrial by-products can be used.

Upon application of clay ground subsoil material of the present invention, the maximum mixing and the addition amount of the high water retention capacity materials and high water-absorbency materials are mixed or the high water-holding capacity materials and high water-absorbency material in water purification cake powder or granular material In consideration of the earth bearing capacity of the ground topsoil when added, the CBR value (Carifornia Bearing Ratio) is adjusted to exceed the design CBR value of 3, which is the limit value of the ground bearing capacity. .

  Furthermore, the lower earth material for clay ground of the present invention may be a mixture of either one of a highly water-retaining material and a highly water-absorbing material with respect to the water purification cake powder, It is more preferable if these are mixed.

When the ground construction is performed using the lower ground material for clay ground of the present invention as described above, the following actions and effects are exhibited.
First of all, the water content of the lower ground material for clay ground of the present invention rises by capillary action, and it becomes possible to keep the ground surface soil in a wet state for a long period of time. It can be shortened.

  Second, unlike the conventional technique in which deliquescent salts are sprayed on the ground topsoil, the ground play iron equipment and physical equipment are not corroded, so that it can be used for a long time and is economical.

Thirdly, since salt does not run away or leach due to rainfall or watering, salt damage to planted plants around the ground can be prevented, and water environmental pollution due to outflow salts can be prevented.
Fourthly, in the conventional technique in which deliquescent salts are sprayed, the salt tends to run away or leach out, so that it is often necessary to perform a spraying process in order to maintain the dust generation suppression effect. However, in the method using the lower soil material for clay ground of the present invention, construction is performed only at the time of ground maintenance or ground renewal. It is.

  Fifth, since the ground temperature of the ground surface is kept low, it is possible to provide a comfortable environment for the ground user. It also helps to mitigate the heat island phenomenon around the ground.

  Sixth, it leads to the recycling of water purification cake, which is an industrial waste, which can secondarily reduce the amount of waste, thereby contributing to the extension of the life of the final waste disposal site.

Next, an embodiment of the present invention will be described with an example.
In the following description, “basic soil material” refers to a “pulverized water cake obtained by pulverizing and sieving the water-purified cake into a powder particle having a particle size of 3 cm or less (= water-purified cake particle according to the present invention)”. Called. In addition, “one with either a high water retention capacity material or a high water absorption capacity material added to the basic subsoil material alone” has a higher water retention capacity than the basic subsoil material. This is called “mat”. Furthermore, what added both the high water retention capacity material and the high water absorption capacity material with respect to the basic subsoil material has a higher water retention capacity compared with the said water retention mat | matte, Therefore This is called "improved water retention mat | matte."
(1) Production Example [Example 1]
By crushing and sieving the purified water cake discharged from the water purification plant, a basic lower layer soil material adjusted to a particle size of 3 cm or less was obtained. 50 to 100 parts by weight of clinker ash was mixed well with 100 parts by weight of this basic lower layer soil material to obtain a water retaining mat.

[Example 2 (modified example of Example 1)]
In place of the clinker ash, a water retention mat having the same performance as in Example 1 can be obtained by using activated carbon having high voids as in the clinker ash, inorganic materials containing activated carbon, zeolite, bentonite, perlite, and vermiculite. Obtainable.

[Example 3]
By crushing and sieving the purified water cake discharged from the water purification plant, a basic lower layer soil material adjusted to a particle size of 3 cm or less was obtained. To 100 parts by weight of the basic lower layer soil material, 0.1 to 2.0 parts by weight of a polyacrylic acid superabsorbent resin was added to obtain a water retaining mat.

[Example 4 (Modification of Example 3)]
Instead of the above polyacrylic acid-based superabsorbent resins, synthetic superabsorbent resins such as polyvinyl-based, polyacrylamide-based, and polyoxyethylene-based materials, and starch-based, cellulose-based, chitin-based, and polyamino acid-based raw materials Even when a degradable natural superabsorbent resin is used, a water retention mat having the same performance as in Example 3 can be obtained.
(2) Example of construction In the place where the ground topsoil and its subsoil were removed due to devastation, the above water retention mat was extended to a depth of 4-10 cm, and after leveling and rolling, the ground topsoil was placed on it. Lay down 5-10cm and level the ground.
(3) Performance test [Test Example 1]
In order to examine how much the water retention capacity of the water retention mat is enhanced by clinker ash kneading, the following test was performed.

  Large grain water purification cake (particle size 1.5-3.0 cm), basic lower layer soil material (water purification cake powder with a particle size of 3 cm or less), water retention mat (equal volume ratio of basic lower layer soil material and clinker ash) 4 kinds of materials were prepared, and each material was filled in a bifunnel funnel having a diameter of 8.5 cm (inner diameter: 7.3 cm) and a height of 4 cm.

  After sufficiently absorbing water from the bottom of the funnel, the gravity water was removed by leaving it in the room for 24 hours. The water retention amount of each material filled at that stage was measured. Next, the funnel filled with each material was left in the room and the weight was measured over time. The water retention capacity of each material was calculated by subtracting the initial filling weight from the weight one day after water absorption per 100 g of the actual material.

[Results and discussion of the above test]
Table 1 below shows the water retention capacity after 24 hours of standing after water absorption.

  The water retention ability was remarkably different depending on the material, and was in the order of clinker ash> water retention mat> basic subsoil material> large grain water purification cake. As is clear from this result, it was possible to increase the water retention capacity of the lower layer soil by mixing clinker ash with a basic lower layer soil material composed of 3 cm or less water purification cake grains.

  FIG. 1 shows the daily water loss of each material. The water retention after 1 day of treatment indicates the water retention capacity in Table 1 above. The water content of the clinker ash was significantly higher than that of the basic subsoil material (particle size of 3 cm or less water purification cake powder), and the water content of the water retaining mat was located between the basic subsoil material and the clinker ash. The cause is considered to be due to the mixing of clinker ash having a high water retention ability.

  In addition, although the water retention amount until 7 days after the treatment was maintained higher in the water retention mat than in the basic lower layer soil material, the period during which the moisture content before the treatment was lowered to the moisture state before the treatment was 13 days later. On the other hand, when clinker ash was used as the lower soil material, it took about 18 days to reach the initial moisture state of the material filling. This suggests that the water retention capacity of the subsoil can be improved by mixing clinker ash in the water retention mat. Therefore, it is suggested that if the mixing ratio of clinker ash with respect to the basic subsoil material is increased, the water retention capacity of the water retention mat is further increased.

  However, if the mixing amount of the clinker ash is too high, the soil strength of the topsoil is lowered and falls below the design CBR value 3 which is a standard of the ground strength of the ground, and there is a limit to the mixing. Therefore, the upper limit of the mixing ratio of the clinker ash with respect to the basic lower layer soil material is equal mixing that does not fall below the above-mentioned reference value.

[Test Example 2]
Next, in order to investigate how much the water retention capacity of the basic lower layer soil material is improved by the addition of the superabsorbent resin, the following test was performed.

  An acrylic column having a diameter of 5 cm and a height of 10 cm is filled with a basic lower layer soil material (water-purified cake powder having a particle size of 3 cm or less), and the water is sufficiently absorbed by raising the capillaries from the bottom of the column. did.

  Further, instead of the above water, a 250-fold and 100-fold dilution of a polymer water retention agent (polyacrylic acid, trade name: ESPEC (registered trademark) L, manufactured by Toyobo Co., Ltd.) Treatment zones for absorbing water (250 times and 100 times) were provided.

  After completion of water absorption, these acrylic columns were allowed to stand indoors for 24 hours to remove gravity water, and the moisture content of the lower layer soil material was measured. Furthermore, it was allowed to stand for 2 weeks to investigate the state of moisture evaporation.

[Results and discussion of the above test]
Table 2 below shows the water retention after 24 hours of standing after water absorption. In the chart, the amount of water retained per 100 g of the actual product is displayed.

  In the treatment group in which the diluted liquid of the superabsorbent resin was absorbed, the water retention amount was higher than that in the control group (basic lower layer soil material). The effect was slightly higher in the 100-fold dilution group with a small dilution factor, but the difference from the 250-fold group was negligible.

  FIG. 2 shows the state of evaporative disappearance of moisture over time after treatment. In the control plot (basic subsoil material), after 10 days of treatment, the water content returned to the same level as when the material was filled. However, in the treated plot where the superabsorbent resin diluted solution was absorbed, 3 more before returning to the same moisture status. It took a day. From this, it has been clarified that the moisture retention amount of the basic lower layer soil material can be maintained high for a longer period of time by subjecting the basic lower layer soil material to wet treatment with a superabsorbent resin.

[Test Example 3]
Next, in order to investigate how much the water retention capacity of the water retention mat is enhanced by the addition amount of the superabsorbent resin, the following test was performed.

  A water retention mat was obtained by mixing the basic lower layer soil material (water purification cake powder having a particle size of 3 cm or less) and clinker ash in an equal volume ratio. In addition, with respect to 100 parts by weight of the obtained water retention mat, polyacrylic acid-based superabsorbent resin (trade name: Glass Power (registered trademark), granules corresponding to 0.1, 0.5, 1.0 part by weight) And Kurita Industry Co., Ltd.) were added to obtain three types of improved water retention mats.

  These four kinds of materials were packed in an acrylic column (diameter 5 cm, height 10 cm) to prepare a 5 cm long soil column. Thereafter, water was sufficiently absorbed from the bottom surface. After removing the gravity water by allowing to stand for 24 hours, the amount of water retained was measured.

Furthermore, the treated section (improved water retaining mat) and the untreated section (water retaining mat) to which 0.1% polyacrylic acid resin was added were allowed to stand for 14 days, and the water loss state was measured.
[Results and discussion of the above test]
Table 3 below shows the water retention amount of each treatment section. The chart is converted to 100g of actual product.

  As is clear from Table 3 above, the water retention capacity increased with the increase in the amount of the superabsorbent resin added, and the water retention capacity of the water retention mat was greatly enhanced. However, the addition of 0.1% or more markedly increased the soil column length with resin swelling. This suggests the possibility of reducing the earth bearing capacity by inducing a decrease in earth bearing capacity. It is obliged to maintain the ground strength of the ground topsoil at a design CBR value of 3 or more. For this purpose, it is considered necessary to keep the amount of the superabsorbent resin added to 0.1% or less.

  FIG. 3 shows the state of evaporation and disappearance of water after standing in a modified water retaining mat section to which 0.1% of a polyacrylic acid-based superabsorbent resin is added and an additive-free water retaining mat section. The water retention capacity at the beginning of filling in the water retention mat section was about 30 g, while the improved water retention mat section increased to about 50 g. The content decreased. Since the water loss pattern in both wards was almost the same, the water condition at the time of filling the material was about 10 days after standing in the water retention mat area, but until the water condition at the time of filling was lowered in the improved water retention mat area. It took about 14 days.

[Test Example 4]
Next, a water retention mat C was obtained by mixing an equal volume of a basic lower layer soil material (water purification cake powder having a particle size of 3 cm or less) and clinker ash in a volume ratio. In addition, polyacrylic acid-based superabsorbent resin (trade name: Glass Power (registered trademark), granular, Kurita Kogyo Co., Ltd.) with respect to 100 parts by weight of the basic subsoil material (water purification cake powder having a particle size of 3 cm or less). A water retention mat D was obtained by adding 0.1 part by weight of the product.

  The basic lower layer soil material, the water retention mat C, and the water retention mat D were each packed into an acrylic column having a diameter of 5 cm to a depth of 5 cm, and the ground top soil was overlaid at a depth of 5 cm. After sufficiently absorbing water from the bottom, gravity water was removed by standing for 24 hours. Then, the moisture evaporation state from the soil surface was investigated by measuring the weight of the acrylic column which stood still. In this test, the amount of water lost due to surface evaporation was displayed per column.

[Results and discussion of the above test]
FIG. 4 shows the state of water evaporation after standing in each treatment section. Water evaporation from the acrylic column occurs mainly from the surface of the topsoil, but in the water retention mat C section where the clinker ash is mixed with the basic lower layer soil as the lower soil material and the water retention mat D section where the superabsorbent resin is added, the basic lower layer It was more than the soil material ward. This suggests that the retained water in the lower layer has risen well in the capillaries, and that more water is transferred in the water retaining mat section.

  FIG. 5 shows the transition of the water content on the topsoil surface. The moisture content fluctuated by synchronizing with the atmospheric humidity, but the content was always higher in the water retention mat C and water retention mat D where the clinker ash and the superabsorbent resin were treated than the basic subsoil. Therefore, it became clear that mixing and addition of these materials to the lower soil material work effectively to maintain the humidity of the surface soil surface.

[Test Example 5]
0.1 parts by weight of a polyacrylic acid superabsorbent resin (trade name: Glass Power (registered trademark)) with respect to 100 parts by weight of a water retaining mat formed by mixing an equal amount of a basic subsoil material and clinker ash in a weight ratio. ), Granular, Kurita Kogyo Co., Ltd.) was added to obtain an improved water retention mat.

  The obtained improved water retention mat, basic subsoil material, jari, and clay mineral soil, and the above four materials are each packed in a 5 cm diameter acrylic column to a depth of 5 cm, and the ground surface soil is then deepened to a depth of 5 cm. Layered. The bottom 1 cm of each acrylic column was immersed in water to absorb water from the bottom, and the time for water to reach the soil surface was measured (first survey). Then, the acrylic column which left still for 24 hours and removed the gravity water investigated the evaporative disappearance state of water | moisture content over time by measuring a weight over 10 days. Then, the bottom surface water absorption situation was investigated again by making the bottom surface water-absorbed again (second investigation).

[Results and discussion of the above test]
Table 4 below shows the time required for moisture to reach the topsoil surface.

  In the first survey, when the improved water retention mat was used as the lower soil, it took 30 minutes for the moisture to reach the topsoil surface. On the other hand, when the basic lower layer soil was used as the lower layer soil, it took 3 hours and 30 minutes for the moisture to reach the surface soil surface. In the other treatment sections, those using viscous mineral soil took 45 minutes, and those using jari took 1 hour 20 minutes.

  In the second survey, which used an acrylic column that had been once water-absorbed and then dried again, the time required to reach was shortened to 20 minutes when the improved water retention mat was used. It took a long time.

The wetting rate of bottom surface water absorption calculated from the average time required for both surveys was 2 minutes 46 seconds for the improved water retention mat, which was significantly shorter than the other treatment areas.
The water retention after 1 day shown in FIG. 6 indicates the maximum water retention capacity of each soil column. When the improved water retention mat was used, the maximum water retention capacity was the highest at 46 g / column. Even when viscous mineral soil was used, a high value was shown, but it took a long time to reach the maximum water retention (see Table 4 above).

  On the other hand, when the basic lower layer soil material was used, the water retention capacity was 20 g / column and less than half of the improved water retention mat. Subsequent disappearance of water did not differ greatly between the materials, but the basic subsoil returned to the water state at the time of column filling 4.5 days after the treatment. On the other hand, in the improved water retention mat material, it took 10 days to return to the moisture state at the time of filling the lower layer soil material.

  Thus, it was judged that if the improved water retention mat was filled in the subsoil, the moisture content of the ground topsoil could be maintained high for a long period of time, and therefore a good clay ground that would not easily generate dust could be created.

[Test Example 6]
An acrylic column with the same diameter was connected to the upper part of the acrylic column filled with soil prepared in Test Example 5 above, and the gap was sealed with vinyl tape so as not to leak water from the connecting portion. After the soil in the acrylic column was wetted in advance, 100 ml of water was gently poured from the top of the acrylic column (corresponding to water depth: 6.02 cm). After standing, the time required for surface water to permeate into the soil and disappear was measured (first survey). Further, after the column was air-dried, the same test was repeated (second investigation).

[Results and discussion of the above test]
Table 5 below shows the water permeability coefficient calculated from the time until water permeates and disappears from the topsoil surface in each treatment section.

  In Table 5 above, the results were obtained using a wetted column (first survey), performed after the column was air-dried and returned to the moisture state immediately after filling (second survey), and the average of both. Values are shown.

The permeability coefficient of each soil column was the highest at 10 ^-2 in the treatment section using jari as the subsoil, and was as low as 10 ^-3 in the other treatment sections. Comparing the average values, the improved water retention mat section had the lowest value after the treatment section with the clay mineral soil as the subsoil. However, the value maintained a value of 10 ⁻³ , and was within the range of allowable values as a ground subsoil. From this, it can be said that the improved water retention mat has not only water retention but also desirable properties as a subsoil material for clay grounds in terms of drainage.

[Test Example 7]
Air-dry clay ground soil, which has become susceptible to sand dust due to aging, and add water to 0, 0.5, 1.0, and 2.0% of the 200g And mixed well. The treated soil was applied to a simple flying sand measuring device shown in FIG. 7 (a) and FIG. 7 (b).

  This simple flying sand measuring instrument scatters the test soil under a constant wind speed and compares the scattering distribution to determine the difficulty of dust generation. The wind source 1 and the wind blowing of the wind source 1 It consists of a sample introduction unit 2 for dropping the test soil from the upper part of the mouth, and a sand collecting mass unit 3 for capturing the test soil scattered by the wind from the blowout port.

  The wind source 1 has one end of a 10 cm long PVC cylindrical tube 12 at the inlet of a sirocco fan 11 (maximum air volume: 650 liters / minute, inlet: diameter 4.5 cm, MB6ZB2 type, manufactured by Oriental Motor Co., Ltd.). The PVC plate 13 is attached to the opening at the other end of the PVC cylindrical tube 12 so as to control the wind speed by adjusting the degree of opening and closing.

  The sample introduction unit 2 is formed by adhering the lower end of an acrylic pipe 22 (30 cm long) having an inner diameter of 3 cm to the upper part of an acrylic cube 21 (4 cm cube) open on both left and right sides, and a polystyrene funnel on the upper end of the acrylic pipe 22. 23.

  The sand collecting mass unit 3 is made of a vinyl sand collecting mass 32 (10 cm square mass, 10 by 10 cm, covered with a hood 31 at the opening on the side of the acrylic cube 21 at the bottom of the sample introduction unit 2. 60 cm).

In addition, the fine sand dust which jumps out from the front-end | tip of the said sand collection mass part 3 was collected using what attached the dust collection hood to the tip of the vacuum cleaner which is not illustrated.
The above-mentioned treated soil was put into the simple flying sand measuring device configured as described above. At the time of charging, each treated soil (about 200 g) is dropped little by little from the polystyrene funnel 23 over about 1 minute, and the scattered dust is collected in each sand collecting mass 32. The weight was measured.

[Results and discussion of the above test]
FIG. 8 shows the scattering distribution of the test soil to which water was added. In air-dried soil (control), there are few things that fall on the sand collection mass 32 with a short sand distance. On the other hand, in the test soil to which water is added and mixed, sand collection with a short sand distance as the amount of water added increases. The amount of sand falling on the mass 32 increased. This suggests that dust generation from the ground can be suppressed by adding a small amount of water.

On the other hand, in the case of using the water retaining mat (clinker ash mixing or Ko吸water soluble resin added basic subsoil material) as a sub-soil material in the above test example 4 was observed that the water content of the surface soil surface is increased.

  Therefore, it is considered that a clay ground with less dust generation can be created by using a water retention mat as a lower layer soil material or an improved water retention mat in which both are mixed and added.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.
For example, in Test Examples 1 to 7, various verifications were performed using a specific high water retention material (clinker ash) and a specific high water absorption material (polyacrylic acid superabsorbent resin). Similar results can be obtained even when tests equivalent to those of Test Examples 1 to 7 are performed using the high water retention materials and high water absorption materials shown in Examples 2 and 4. Therefore, the highly water-retaining material and the highly water-absorbing material shown in Examples 2 and 4 can also be used as the highly water-retaining material and the highly water-absorbing material in the present invention.

The graph which shows the daily water | moisture-content loss | disappearance condition of each material in the test example 1. FIG. The graph which shows the evaporative loss state of the water | moisture content of the daily passage after the process in Experimental example 2. FIG. The graph which shows the evaporation loss | disappearance condition of the water | moisture content after standing of each material in the test example 3. FIG. The graph which shows the water | moisture-content evaporation state after stationary of each process area in Test Example 4. FIG. The graph which shows transition of the moisture content of the topsoil surface in Test Example 4. The graph which shows the water retention ability of the improved water retention mat | matte in Experiment 5, and the water | moisture-content loss | disappearance condition. It is a figure which shows the structure of a simple flying sand measuring device, (a) is the elevation view, (b) is the top view. The graph which shows the scattering distribution of the test soil which added the water in the test example 7. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wind power source, 2 ... Sample introduction part, 3 ... Sand collection mass part, 11 ... Sirocco fan, 12 ... Cylindrical pipe made of PVC, 13 ... PVC board, 21 ..Acrylic cube, 22 ... acrylic pipe, 23 ... polystyrene funnel, 31 ... food, 32 ... sand collection mass.

Claims (5)

"Purified water that has been made into powder particles with a particle size of 3 cm or less by crushing and sieving the water-purified cake obtained by pressurizing, dehydrating, or drying the sun, which is generated during the water treatment process at the water purification plant For `` cake powder granules ''
“Made of activated carbon, zeolite, bentonite, clinker ash, perlite, vermiculite, and ALC (Autoclaved Lightweight aerated Concrete) powders, which can be held against gravity. The water content per unit weight is mixed with the high water retention capacity material that is larger than the purified water cake powder,
Clay, wherein; (subgrade soil bearing capacity ratio Carifornia Bearing Ratio) that is prepared as above design CBR value 3 the amount of the high water retention capacity materials for the water purification cake powder or granular material, CBR value Lower soil material for ground. "Purified water that has been made into powder particles with a particle size of 3 cm or less by crushing and sieving the water-purified cake obtained by pressurizing, dewatering, or sun-drying the precipitate generated during the water treatment process at the water purification plant For `` cake powder granules ''
`` Starch-based biodegradable superabsorbent resin, cellulose-based biodegradable superabsorbent resin, chitin-based biodegradable superabsorbent resin, polyamino acid-based biodegradable superabsorbent resin, polyacrylic acid-based non-biodegradable Choose from synthetic superabsorbent resin, polyvinyl alcohol non-biodegradable synthetic superabsorbent resin, polyacrylamide non-biodegradable synthetic superabsorbent polymer, and polyoxyethylene non-biodegradable synthetic superabsorbent polymer It is a material that consists of any one kind or a mixture of two or more kinds, and does not separate the water contained in the resin structure by gravity, and the water content per unit weight that can be contained is the water purification cake powder. "High water absorption material that is larger than"
The amount of the high water-absorbing material blended in the water-purified cake powder is adjusted so that the CBR value (Carifornia Bearing Ratio) exceeds the design CBR value of 3. Lower soil material for ground. "Purified water that has been made into powder particles with a particle size of 3 cm or less by crushing and sieving the water-purified cake obtained by pressurizing, dehydrating, or drying the sun, which is generated during the water treatment process at the water purification plant For `` cake powder granules ''
“Made of activated carbon, zeolite, bentonite, clinker ash, perlite, vermiculite, and ALC (Autoclaved Lightweight aerated Concrete) powders, which can be held against gravity. High water-retaining capacity material whose water content per unit weight is larger than that of the water-purified cake powder, ”“ starch-based biodegradable superabsorbent resin, cellulose-based biodegradable superabsorbent resin, chitin-based biomaterial ” Degradable superabsorbent resin, polyamino acid-based biodegradable superabsorbent resin, polyacrylic acid-based non-biodegradable synthetic superabsorbent resin, polyvinyl alcohol-based non-biodegradable synthetic super-absorbent resin, polyacrylamide-based non-biodegradable Any one or more selected from degradable synthetic superabsorbent resin and polyoxyethylene non-biodegradable synthetic superabsorbent resin Is a material that does not separate the water contained in the resin structure by gravity, and the water content per unit weight that can be included is larger than that of the water-purified cake granule. ”
The amount of the high water-holding capacity material and the high water-absorbency materials for the water purification cake powder or granular material, CBR value (Carifornia Bearing Ratio; subgrade soil bearing capacity ratio) is prepared as above design CBR value 3 A subsoil material for clay ground characterized by that. The high water-absorbing material is a starch-based biodegradable superabsorbent resin, a cellulose-based biodegradable superabsorbent resin, a chitin-based biodegradable superabsorbent resin, or a polyamino acid-based biodegradable superabsorbent resin. The lower earth material for clay ground according to claim 2 or 3, wherein the material is made of any one or a mixture of two or more selected from. 5. A clay ground construction method, comprising: spreading the lower soil material for clay ground according to any one of claims 1 to 4;

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