JP2023021750A - Spray material composition and method for spraying construction - Google Patents

Abstract

To provide a spray material composition that can reduce a spatial dose of radiation and can maintain a thickness of a soil cover for a long time.SOLUTION: There is provided a spray material composition including a spray base material, a joint agent, a thickener, and a thickening accelerator, and water. The spray base material includes a vegetation base material, a specific gravity improvement material thicker than the vegetation base material, and an absorbent for absorbing a radiation material. The spray material composition is mixed with a physical characteristics adjusting material so that the composition can function effectively as a soil cover material for an inclined surface. The spray material composition can absorb a radioactive material and can shield radiation effectively.SELECTED DRAWING: None

Description

The present invention relates to a spraying material composition and a spraying method.

Conventionally, in order to reduce air doses in forests contaminated with radioactive materials that have come flying in, soil-covering agents that are sprayed on the surface of the soil in the forest to absorb the radioactive materials contained in the soil and block radiation have been used. It has been proposed (Patent Document 1).

JP 2014-142251 A

However, depending on the materials used and the condition of the target soil, it may not be possible to cover the soil sufficiently to shield radiation. For example, a material with a low specific gravity has an insufficient shielding effect. In addition, it is difficult to ensure the thickness of the cover soil in the spraying of a water-containing material that exceeds the liquid limit, and even if the thickness of the cover soil is secured, there is a risk that the cover soil will be washed away due to the passage of time or rainfall. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a spray material composition capable of reducing the air dose of radiation and maintaining the soil covering thickness over a long period of time. Another object of the present invention is to provide a spraying method using this spraying material composition.

The present invention includes a spray base material, a binder, a thickener, a densification accelerator, and water, and the spray base material includes a vegetation base material and a specific gravity improvement that is denser than the vegetation base material. A spray material composition is provided that includes a material and an adsorbent that adsorbs radioactive materials.

This spraying material composition can function effectively as a soil covering material by being mixed with a physical property-adjusting material, which will be described later. This soil covering material can adsorb radioactive substances and has a high radiation shielding effect. And even if it sprays to an inclined surface, sufficient covering soil thickness can be ensured and the covering soil thickness can be maintained over a long period of time.

In this spraying material composition, the content ratio of the vegetation base material, the specific gravity improving material and the adsorbent may be 10-60:30-89.9:0.1-10 on a volume basis. As used herein, the term "volume" refers to the volume of a substance to be measured, which is measured by putting it twice in a graduated container, tapping it 10 times, and scraping it off. Also, the weight per volume at this time is defined as the bulk density.

In this spraying material composition, 0.1 to 10 parts by volume of a bonding agent, 0.01 to 5 parts by volume of a thickening agent, and 0.01 to 0.01 part of a solidification accelerator are added to 100 parts by volume of a base material to be sprayed. 2 parts by volume, and may contain 30 to 100 parts by volume of water.

In this spray material composition, the binder may be polyvinyl acetate, the thickener may be a polysaccharide, and the seed-filling accelerator may contain a polymeric soil conditioner.

In this spraying material composition, the vegetation base material contains at least one selected from the group consisting of bark compost, peat moss, coconut fiber, fermented coconut shells and leaf mulch, and the specific gravity improving material contains sand, gravel, clay, silt, At least one selected from the group consisting of black earth, barium and titanium may be included, and the adsorbent may include at least one selected from the group consisting of zeolite, smectite, weathered mica, vermiculite and illite.

The spray material composition may further include physical property modifiers. The physical property-adjusting material includes at least one selected from the group consisting of sawdust, bean curd refuse, rice husk charcoal, corn cobs, biochar, coffee husks, tea husks, used paper, cellulose, cotton, coconut husks and coconut fibers. things are mentioned.

The present invention provides a method of spraying, in which the above-mentioned spraying material composition and physical property-adjusting material are discharged from different discharge ports and simultaneously sprayed onto the ground. Alternatively, the spraying may be performed by spraying a spraying material composition containing a physical property modifier onto the ground.

When this spraying material composition is sprayed onto the ground, a soil covering thickness can be ensured at the sprayed location due to the absorption and retention of water by the physical property-adjusting material. Then, the soil particles are concentrated in the lower portion due to the function of the densifying accelerator, and the concentrations of the bonding agent and the thickening agent form a gradient in the depth direction of the soil. In the vicinity of the surface of the covering soil, where the concentration of the binder and the thickener increases, as the covering soil dries, the binder forms a coating and the thickener strengthens the coating, thereby preventing raindrop erosion. In the interior of the covering soil where the concentration of the binder and the thickener is low, the bonding agent causes the soil particles to adhere to each other, but the soil is not as hard as the surface of the covering soil and is relatively soft.

ADVANTAGE OF THE INVENTION According to this invention, while being able to reduce the space dose of radiation, it is possible to provide the spraying material composition which makes it possible to maintain the soil covering thickness over a long period of time. Also, a spraying method using this spraying material composition can be provided.

It is a graph which shows the relationship between the elapsed time from the time of mixing of material, and viscosity. It is a graph which shows the diameter and soil thickness in a pseudo slump test. It is a graph which shows the relationship between the elapsed time from the time of mixing of material, and viscosity. It is a graph which shows the diameter and soil thickness in a pseudo slump test. It is a graph which shows Yamanaka type soil hardness.

Hereinafter, a spraying material composition and a spraying method using this spraying material composition will be described as preferred embodiments of the present invention. This spraying material composition and spraying method can be used to reduce air doses in forests contaminated with radioactive substances. In particular, the spraying material composition of the present embodiment is effective as a covering material after stripping off the surface layer of soil for decontamination of radioactive substances.

Conventionally, forest decontamination was carried out mainly on forest edges, and the main method was to remove sediments such as fallen leaves. Radioactive substances circulate in forests through plant growth and litter, and exist in soil and plant bodies. In order to decontaminate radioactive substances from the soil, it is necessary to strip the surface layer of the soil up to 5 cm (up to about 15 cm at maximum). When the soil is stripped, it is desirable to cover it with soil in order to reduce adverse effects on vegetation and shield remaining radiation.

There are vegetation base spraying methods and additional soil spraying methods as soil covering methods, but both of them have problems in terms of materials and construction methods. In other words, issues related to materials include radiation shielding effects and adsorption of radioactive substances. In general, the radiation shielding effect increases as the cover soil becomes thicker and has a higher specific gravity. In addition, some of the radioactive substances in the forest are absorbed by plants from the soil and re-diffuse into the environment through fallen leaves and branches. It is conceivable to mix materials.

On the other hand, as a construction method issue, in order to form a thick cover soil of 5 cm or more, vegetation base spraying is selected by pneumatically spraying a material below the liquid limit, but a large compressor that cannot be easily moved is selected. It is difficult to work in confined spaces or in forests because it requires the installation of a dedicated plant. In addition, since it is essential to construct a lath net to fix the cover soil and prevent it from being washed away, artificial objects remain in the soil. In addition, the soil spraying work can be carried out in confined spaces by on-vehicle equipment, but since the material is a slurry containing a lot of water, the spraying thickness is at most 3 cm. can't Also, if a material with a large specific gravity is mixed in order to enhance the radiation shielding effect, the material may settle in the mixing tank, resulting in insufficient mixing of the materials or separation of the materials during spraying.

The spraying material composition of the present embodiment has been devised in view of the above points, and by spraying it onto the ground as additional soil, it is possible to reduce the spatial dose of radiation and to ensure the thickness of the soil cover. is. Radioactive substances of primary interest are radioactive cesium and radioactive strontium. Among them, cesium-137 and cesium-134, strontium-89 and strontium-90 are targeted.

The spraying material composition of this embodiment comprises a spraying base material, a bonding agent, a thickener, a compacting accelerator, and water. Among these, the water may be any tap water or the like. The content of water may be 30 to 100 parts by volume, or may be 40 to 80 parts by volume with respect to 100 parts by volume of the base material to be sprayed.

(spray base material)
The spray base material includes a vegetation base material, a specific gravity improving material, and an adsorbent for radioactive substances. The sprayed base material absorbs radioactive substances by means of an adsorbent, and its specific gravity is increased by means of a material for improving the specific gravity, thereby enhancing the radiation shielding effect. In addition, since it contains a vegetative substrate, it also works as a growth base for plants. The sprayed base material may have a dry bulk density of 0.5 to 2.0 g/cm ³ , and may be 0.6 to 1.4 g/cm ³ .

The vegetation substrate preferably has water retention necessary for plant growth, and is preferably an organic material. The vegetation base material preferably contains at least one selected from the group consisting of bark compost, peat moss, coconut fiber, fermented coconut shells and leaf mulch. The specific gravity of the vegetation substrate is preferably 0.05 to 0.45 g/cm ³ and more preferably 0.15 to 0.3 g/cm ³ .

The specific gravity improving material is added to increase the specific gravity of the spraying material composition, and has a higher specific gravity (density) than the vegetation base material. The specific gravity improving material is preferably an inorganic material, and preferably contains at least one selected from the group consisting of sand, gravel, clay, silt, black soil, barium and titanium. The specific gravity of the specific gravity improving material is preferably 0.6 to 4.6 g/cm ³ and more preferably 0.8 to 3.0 g/cm ³ . The particle size of the specific gravity-improving material is preferably less than 10 mm when measured by a sieving method and a pipette method, and preferably accounts for 90% or more by weight of the particles. At the same time, the content by weight of particles less than 0.075 mm is preferably less than 50%, more preferably less than 15%, even more preferably less than 5%.

As the adsorbent, one having a property of adsorbing radioactive substances is used. From the viewpoint of targeting radioactive cesium, it is preferably a layered silicate clay mineral, and preferably contains at least one selected from the group consisting of zeolite, smectite, weathered mica, vermiculite, and illite. The particle size of the adsorbent is preferably 0.005 to 8 mm, preferably 0.075 to 2 mm, and more preferably 0.5 to 1 mm when measured by a sieving method or a pipette method. preferable.

The content ratio (blending ratio) of the vegetation base material, the specific gravity improving material and the adsorbent may be 10-60:30-89.9:0.1-10 on a volume basis. Here, the content ratio of the vegetation substrate may be 15-55, or 20-50. The content ratio of the specific gravity improving material may be 40-80, or may be 50-70. The content ratio of the adsorbent may be 1-8, or 3-6.

(bonding agent)
Binders serve to bond soil particles together after spraying and to form a film on the surface of the soil. The bonding agent is preferably an organic polymer, and particularly preferably polyvinyl acetate, ethylene-vinyl acetate copolymer, or polyvinyl alcohol. The content of the bonding agent may be 0.1 to 10.0 parts by volume, 0.5 to 5.0 parts by volume, or 1.0 to 10.0 parts by volume relative to 100 parts by volume of the base material to be sprayed. It may be 3.0 parts by volume. The bulk density of the bonding agent may be 0.8-1.2 g/cm ³ , or 0.9-1.1 g/cm ³ .

(thickener)
The thickener increases the viscosity of the spraying material composition during mixing and prevents the separation of materials having different specific gravities. After spraying, it works to strengthen the coating structure on the soil surface and also prevents raindrop erosion. Thickeners may be biodegradable and are preferably polysaccharides. Polysaccharides include guar gum, gum arabic, xanthan gum, carboxymethylcellulose, tamarind seed gum, carrageenan, karaya gum, succinoglycan, locust bean gum, soybean polysaccharides, pullulan, psyllium seed gum, curdlan, alginic acid/PGA, gellan gum, glucomannan, agar, pectin and the like. Among these, guar gum containing galactomannan as a main component is preferred. The content of the thickener may be 0.01 to 5.0 parts by volume, 0.1 to 3.0 parts by volume, or 0.2 parts by volume with respect to 100 parts by volume of the base material to be sprayed. It may be up to 1.0 parts by volume. The bulk density of the thickener may be 0.4-0.9 g/cm ³ , or 0.6-0.7 g/cm ³ .

(Dense-enhancing agent)
The densification accelerator promotes the agglomeration of the sprayed base material and the separation of the sprayed base material from water after spraying, and functions to promote early densification of the soil by sedimentation of the sprayed base material. is. In addition, the compacting accelerator also functions to increase the viscosity when mixing the materials of the spray material composition and to prevent the separation of materials having different specific gravities. The densifying accelerator is preferably a polymeric soil conditioner, and preferably contains optional components. The polymer soil conditioner may be either an anionic polymer soil conditioner or a cationic polymer soil conditioner, and may function as a flocculant. Optional components include aluminum sulfate, carbonates, organic acids, and the like.

The anionic polymer soil conditioner is not particularly limited, but examples include copolymers of acrylamide and (meth)acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid or salts thereof, poly A partial hydrolyzate of acrylamide or the like can be used. Among them, it is preferable to use a compound having a molecular weight of several hundred thousand to several million. Moreover, from the viewpoint of improving the aggregation effect of soil particles, it is preferable to use a compound having a strong acid group such as a sulfonic acid group or a carboxylic acid group. These can be used individually by 1 type or in combination of 2 or more types.

The cationic polymer soil conditioner is not particularly limited, but for example, acrylamide and dialkylaminoalkyl (meth)acrylate, dialkylaminoalkyl (meth)acrylamide, or a cationic monomer such as a salt or quaternary product thereof or a homopolymer or copolymer of these cationic monomers. From the viewpoint of improving the effect of aggregating soil particles, it is preferable to use a compound having a strong base such as an amino group. These can be used individually by 1 type or in combination of 2 or more types.

From the viewpoint of enhancing the effect of aggregating soil particles, it is preferable that 50% by mass or more of the total amount of aluminum sulfate contained in the additive have a particle size of 0.15 mm or less. In addition, 60% by mass or more of aluminum sulfate preferably has a particle size of 0.15 mm or less, more preferably 80% by mass or more has a particle size of 0.15 mm or less, and the total amount has a particle size of 0.15 mm or less. is most preferred.

Whether the particle size of aluminum sulfate is 0.15 mm or less is confirmed by using a 100-mesh sieve (opening 0.15 mm), and the particles that have passed through the 100-mesh sieve are treated as particles with a particle size of 0.15 mm or less. and That is, of the aluminum sulfate in the additive, it is preferable that the particles passing through a 100-mesh sieve account for 50% by mass or more of the total amount of aluminum sulfate.

The content of aluminum sulfate in the additive is preferably 10 to 85% by mass, preferably 28 to 85% by mass, based on the total amount of the additive, from the viewpoint of obtaining an excellent aggregation effect and an excellent aggregation rate. more preferably 35 to 50% by mass. Aluminum sulfates having different particle sizes can be used in combination.

If the additive optionally contains aluminum sulphate, it preferably contains a carbonate at the same time. Since aluminum sulfate becomes acidic when dissolved in water, the additive tends to precipitate when alkaline. Therefore, when the additive contains an alkaline carbonate, the effect of aggregating soil particles can be quickly obtained. From the viewpoint of obtaining this effect more sufficiently, the content of carbonate in the additive is preferably 10 to 75% by mass, more preferably 28 to 70% by mass, based on the total amount of the additive. More preferably, it is up to 57% by mass. As the carbonate, one containing an alkali metal ion is preferred, and sodium carbonate is preferred.

The organic acid functions to prevent the anionic polymeric soil conditioner and the cationic polymeric soil conditioner from hardening together. That is, the anionic polymeric soil conditioner and the cationic polymeric soil conditioner react with each other to form polymer clumps, which is suppressed by the presence of the organic acid. From the viewpoint of sufficiently obtaining this effect, the content of the organic acid in the additive is preferably 15% by mass or less, more preferably 1.5 to 7% by mass, based on the total amount of the additive.

The organic acid preferably contains at least one selected from the group consisting of malic acid, sulfamic acid, oxalic acid, citric acid and tartaric acid.

Other optional components of the densification accelerator include antifreeze agents, preservatives, thickeners, and the like.

The content of the densifying accelerator is 0.01 to 2.0 parts by volume with respect to 100 parts by volume of the sprayed base material when the bulk density of the sprayed base material is 1.0 g/cm ³ . It may be from 0.05 to 1.5 parts by volume, or from 0.1 to 0.8 parts by volume. This lower limit may be 0.18 volume parts or 0.23 volume parts. The bulk density of the densifying accelerator may be 0.5 to 1.0 g/cm ³ or 0.7 to 0.8 g/cm ³ .

(physical properties adjusting material)
The physical property modifier functions to absorb excess water contained in the spray material composition and to ensure spray thickness. Even when the spray material composition is applied to an inclined surface, the spray material composition remains in place without dripping. The physical property-modifying material is preferably an organic material, the group consisting of sawdust, bean curd refuse, rice husk charcoal, corn cobs, biochar, coffee husks, used tea lees, waste paper, cellulose, cotton, coconut husks and coconut fibers. It is preferable to include at least one selected from. The physical property modifier may be an artificial water absorbent material, such as a superabsorbent polymer. Examples of superabsorbent polymers include polyacrylamide, sodium polyacrylate, polyacrylic acid, and natural polymers obtained by processing natural polysaccharides such as starch, chitosan, and cellulose. The bulk density of the physical property modifier may be from 0.1 to 0.7 g/cm ³ , or from 0.2 to 0.4 g/cm ³ .

The physical property modifier may be mixed with each of the above materials as a component of the spray material composition, or may be separate from each of the above materials. If it is different from each of the above materials, then two materials are sprayed: a spray material composition that does not contain the physical property modifier and the physical property modifier.

The content of the physical property-adjusting material in the spraying material composition, or the amount of the physical property-adjusting material used for two-material spraying with the spraying material composition, is 0.01 to 0.01 with respect to 100 parts by volume of the base material to be sprayed. It may be 60 parts by volume, 0.05 to 50 parts by volume, or 0.1 to 40 parts by volume.

(Construction method)
As a procedure for spraying, there are two-material spraying, in which the physical property-adjusting material is treated separately, and single-material spraying, in which the physical property-adjusting material is preliminarily mixed with the spraying material composition. As a procedure for spraying two materials, first, the base material to be sprayed, the bonding agent, the thickener, the compacting accelerator, and water are put into the tank of the hydroseeder, and mixed and stirred. As the stirring is continued, the viscosity gradually increases and the spray material composition is adjusted.

Here, it is preferable that the viscosity of the spraying material composition is such that material separation does not occur and spraying can be easily performed. For example, the viscosity measured with a Brookfield viscometer may be 1000 to 5000 cP (centipoise), 1500 to 4500 cP, or 2000 to 4000 cP after 50 seconds from the start of mixing the materials. may

The spraying material composition and the physical property-adjusting material are pumped and discharged from separate nozzles and sprayed onto the soil. The soil to be sprayed may be soil from which the surface layer has been stripped for decontamination of radioactive substances. Further, the soil may be horizontal or may be an inclined surface. In the case of an inclined surface, the inclination angle may be up to 45°. Spraying is aimed at the same place with two materials at the same time. Then, the two materials are mixed at the sprayed portion, and the physical property-adjusting material immediately absorbs the water contained in the spraying material composition, and the fluidity of the spraying base material is lowered to form a thick layer. This allows the target soil to be covered. The soil covering thickness may be greater than 3 cm, or even greater than 5 cm.

As a single material spraying procedure, the spraying base material, bonding agent, thickener, solidification accelerator, physical property adjusting material, and water are put into the tank of the Hydro Seeder, and mixed and stirred. I do. Since the physical property modifier absorbs water even during agitation, it is desirable to shorten the time interval between spraying. Also, a pump with a higher pumping force than in the case of two-material spraying is used. In this case, the viscosity of the spray material composition should not exceed the limit that can be pumped. For example, the viscosity measured with a Brookfield viscometer may be 4500 to 8000 cP, or may be 5000 to 7000 cP.

(Effect)
The spraying material composition sprayed onto the soil forms a soil cover at the sprayed location due to absorption of water by the physical property modifier. Then, due to the function of the densifying accelerator, the soil particles aggregate and settle, and are concentrated in the lower part. As a result, separation of the solid content and water of the spray material composition progresses, and a gradient occurs in the concentrations of the binder and the thickener in the depth direction of the cover soil. Near the surface of the cover soil (about 1 to 1.5 cm deep) where the concentration of the binder and thickener increases, the formation of a film by the binder and the strengthening of the film by the thickener occur as the cover soil dries. This can prevent raindrop erosion. On the other hand, inside the covering soil where the concentrations of the binder and the thickener are low, the soil particles aggregated by the seed-packing accelerator adhere to each other by the binder, but the gap is kept moderately, and the plant roots grow. It is prone to hardness that does not pose a problem. Therefore, vegetation is often possible in the cover layer formed by spraying.

Since the spraying material composition of the present embodiment contains an adsorbent that adsorbs radioactive substances, it is possible to immobilize the radioactive substances in situ by adsorption, thereby stopping the circulation of the radioactive substances in the forest. can. Further, since the spraying material composition of the present embodiment contains the specific gravity improving material, the effect of shielding radiation is high, and the air dose of radiation in the forest can be reduced.

The spraying material composition of the present embodiment and its application method can simultaneously compensate for the shortcomings of the conventional soil covering method. That is, in the conventional vegetation base spraying work, it was necessary to install a dedicated plant in order to form a thick cover soil exceeding 5 cm, and it was difficult to work in narrow places or in forests, but the construction method of this embodiment. Then, it is enough if there is a place where the hydro seeder can be installed. In addition, since construction of a lath net to prevent the cover soil from being washed away is unnecessary, no man-made objects remain in the soil. In addition, in the soil spraying work, since the material is a slurry containing a lot of water, the spraying thickness is at most 3 cm, and it was not possible to secure the covering soil thickness. Therefore, even when a water-containing material exceeding the liquid limit is sprayed, it is possible to secure a covering soil thickness exceeding 5 cm immediately after spraying.

In addition, conventionally, if a material with a large specific gravity is mixed in order to enhance the radiation shielding effect, there is a risk that the material will settle in the mixing tank and separate during spraying. In , the viscosity of the mixture is increased due to the action of the thickener and the compacting accelerator, and material separation is prevented.

EXAMPLES The content of the present invention will be more specifically described below with reference to examples and comparative examples. In addition, the present invention is not limited to the following examples.

<Materials used>
Spraying base material: "Fujimi Soil" (trade name) (manufactured by Fujimi Kogyo Co., Ltd., the main component is bark compost, bulk density 0.18 g / cm ³ ) as a vegetation base material 40% by volume, mountain sand ( Particle size: 90% or more of 2.0 to 0.075 mm) 55% by volume, 5% by volume of zeolite (particle size: 0.5 to 1.0 mm) as an adsorbent. Vinyl acetate copolymer (bulk density 1.1 g/cm ³ )
・Thickening agent: a mixture of galactomannan and polyethylene glycol (bulk density 0.6 to 0.7 g/cm ³ )
・Densification accelerator: a mixture of sodium carbonate, aluminum sulfate and a polymer (bulk density 0.7 to 0.8 g/cm ³ )
・Physical property adjusting material: Sawdust (bulk density: 0.17 g/cm ³ )

<Measurement of viscosity and pseudo-slump test>
Each material was mixed according to the formulation shown in Table 1 to prepare spray material compositions of Comparative Examples 1 to 8 and Example 1, respectively. The viscosity of each spray material composition was measured over 140 seconds with a Brookfield viscometer. The results are shown in FIG.

Next, 300 ml of the spray material compositions of Comparative Examples 1 to 7 were filled in a 250 ml plastic bottle (3.2 cm in diameter), and the plastic bottle was turned upside down at a height of 10 cm and dropped into the vat. The height (soil thickness) of the dropped spray material composition and the spreading diameter (diameter) in plan view were measured. Since it was clear that the spray material compositions of Comparative Example 8 and Example 1 had lower fluidity than those of Comparative Examples 1 to 7, 300 ml of the spray material composition was placed in a 300 ml beaker (diameter: 9.0 cm). After filling, the plastic bottle was turned upside down at a height of 2 cm and dropped into the vat. The height (soil thickness) of the dropped spray material composition and the spreading diameter (diameter) in plan view were measured. The results are shown in FIG.

From these results, sufficient soil thickness cannot be obtained by simply increasing the concentration of binders and thickeners, and sufficient soil thickness can be obtained by blending compacting accelerators and physical property modifiers. Do you get it.

<Study of blending amount of thickener and densifying accelerator>
Each material was mixed according to the formulation shown in Table 2 to prepare spray material compositions of Examples 2 to 7, respectively. The viscosity of each spray material composition was measured over 120 seconds with a Brookfield viscometer. The results are shown in FIG.

Next, the spray material compositions of Examples 2 to 7 were subjected to a pseudo-slump test using a 300 ml beaker (diameter 9 cm) in the same manner as described above. ) and the spread diameter (diameter) in plan view were measured. The results are shown in FIG.

Furthermore, the Yamanaka soil hardness was determined for the spray material compositions of Examples 2 to 7. As a method for determining the Yamanaka soil hardness, a Yamanaka soil hardness tester was inserted into the dry spray material composition. The results are shown in FIG. Here, the determination of the Yamanaka soil hardness as a planting base is as follows (Japanese Institute of Landscape Architecture Greening Environmental Engineering Committee (2000), Planting Base Maintenance Manual in Greening Project, Landscape Research, 63, 224-241 ).
27mm< …difficult to penetrate many roots 24mm～27mm …inhibition of root system development 20mm～24mm …some tree species inhibiting root system development )

From these results, it was found that the viscosity varies depending on the formulation, but sufficient soil thickness can be obtained with any formulation. In addition, it was found that depending on the amount of the thickener and the seed-packing accelerator added, the hardness of the soil may become so high that the development of the plant root system is inhibited.

<Actual machine test>
A spray material composition of Example 8 was prepared by mixing each material (excluding sawdust) according to the formulation shown in Table 3. When the viscosity was measured with a Brookfield viscometer from the time the materials except the physical property modifier were mixed, the viscosity was maintained at 2000 to 4000 cP after 50 seconds from the start of mixing. Using a hydro-seeder mounted on a vehicle, this spraying material composition and sawdust were sprayed onto four types of inclined planes of 0°, 15°, 30° and 45°. The inclined surface was prepared by tilting a water-resistant lauan plywood plate and placing a non-woven fabric mat on the surface, and sprayed to a thickness of more than 5 cm.

Although there was rainfall of about 30 mm/day (maximum 5 mm/h) on the next day after spraying, the sprayed soil did not wash away. The soil hardness exceeded 1.5 kg/cm ² after 5 days of spraying, exceeded 5 kg/cm ² after 8 days, and exceeded 10 kg/cm ² after 12 days. After 12 days, no material separation or washout occurred in the soil on any of the slopes, maintaining a soil thickness of over 5 cm.

The invention can be used for spraying soil material onto sloped surfaces.

Claims (9)

comprising a spray base material, a binder, a thickening agent, a compacting accelerator, and water;
A spraying material composition, wherein the spraying base material includes a vegetation base material, a specific gravity improving material having a higher density than the vegetation base material, and an adsorbent that adsorbs radioactive substances. 2. The spraying material composition according to claim 1, wherein the content ratio of said vegetation base material, said specific gravity improving material and said adsorbent is 10-60:30-89.9:0.1-10 on a volume basis. 0.1 to 10 parts by volume of the bonding agent, 0.01 to 5 parts by volume of the thickening agent, and 0.01 to 2 parts by volume of the compacting accelerator for 100 parts by volume of the base material to be sprayed. , 30 to 100 parts by volume of water. The spray material composition of any one of claims 1 to 3, wherein the binder is polyvinyl acetate, the thickener is a polysaccharide, and the compacting enhancer comprises a polymeric soil conditioner. thing. The vegetation base contains at least one selected from the group consisting of bark compost, peat moss, coconut fiber, fermented coconut shells and leaf mulch,
The specific gravity improving material contains at least one selected from the group consisting of sand, gravel, clay, silt, black soil, barium and titanium,
The spray material composition according to any one of claims 1 to 4, wherein the adsorbent contains at least one selected from the group consisting of zeolite, smectite, weathered mica, vermiculite and illite. The spray material composition of any one of claims 1-5, further comprising a physical property modifier. The physical property-adjusting material includes at least one selected from the group consisting of sawdust, bean curd refuse, rice husk charcoal, corn cobs, biochar, coffee husks, tea husks, waste paper, cellulose, cotton, coconut husks and coconut fibers. 7. A spray material composition according to claim 6. A spraying method, wherein the spraying material composition according to any one of claims 1 to 5 and the physical property-adjusting material are discharged from different discharge ports and simultaneously sprayed onto the ground. A spraying method, comprising spraying the spraying material composition according to claim 6 or 7 onto the ground.

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