JPS628561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for preventing ground damage caused by frost heave phenomenon in winter on roads, playgrounds, courts, etc. in cold regions, and its purpose is to improve frost heave prevention performance. The objective is to provide a ground insulation method that improves work efficiency and improves work efficiency.

In cold regions, when the temperature drops below 0°C in winter, water in the ground freezes, and the ground lifts unevenly due to the growth of ice crystals, causing cracks to occur. Furthermore, as the temperature rises, the ice crystals melt from the surface side, which significantly reduces the supporting capacity of the surface layer, eventually leading to the destruction of the ground.

Measures to prevent the above-mentioned frost heaving phenomenon include replacement methods, insulation methods, chemical treatment methods, water-blocking methods, and the like. Among these methods, the replacement method involves replacing the subgrade soil within the frozen depth with a material that is less likely to cause frost heave, which poses problems in terms of excavation time and disposal of leftover soil. Additionally, chemical treatment methods that lower the freezing temperature by adding cryogens such as calcium chloride, and methods that lower the groundwater level by installing drainage channels, are ineffective unless the construction is done on a relatively large scale and carefully. Although it is temporarily effective, it has various drawbacks, such as not lasting for a long period of time, and cannot be said to be a fundamental frost heaving prevention method.

On the other hand, the insulation method involves providing a heat insulating layer between the surface layer and the ground or roadbed to prevent outside air temperature from being conducted into the ground, thereby preventing underground moisture from freezing. This construction method uses a foamed plastic molded plate as described in Japanese Patent Application Laid-open No. 17245/1983.
Methods of forming a heat insulating layer are known. In this method, a sand layer is built on the roadbed dug 10cm to 100cm underground, and then foamed plastic molded boards are laid down.
This is then covered with sand again, sprinkled with roadbed material such as crushed stone, and finished with asphalt, concrete, etc. However, with this method, it is essential to provide a layer of sand on top of the molded plastic plate because the foamed plastic molded board is susceptible to misalignment due to impact during construction and is easily damaged by sharp edges of crushed stone. Furthermore, cutting and joining operations are required to suit the shapes of drainage ditches, exposed pipes, manholes, etc. in the excavated roadbed, making the actual operations extremely complex.

In addition, as belonging to the same insulation method,
Japanese Patent Publication No. 43-2025 describes a method of forming a heat insulating layer using a cement mortar layer mixed with particles of a foamed synthetic resin such as expanded polystyrene, and Japanese Patent Publication No. 48-25974 describes a method of forming a heat insulating layer using a foamed polyurethane composition. A method of forming a heat insulating layer of polyurethane foam by spraying is described. However, since the former idea is limited to providing heat insulation to concrete, the thermal conductivity of the cement mortar layer does not become as low as expected. In addition, the latter must satisfy the foaming conditions for foamable polyurethane compositions when working on the road, and in order to carry out room temperature foaming in cold regions where frost heaving occurs, facilities for this purpose,
There are still problems with practical application, such as the need for equipment and the problem of fluorocarbon gas in foamed polyurethane.

The present invention belongs to a heat insulation method, in which at least one type of flocculent material selected from asbestos, rock wool, mineral wool, glass wool, and cellulose fiber having water repellency and antiseptic properties is applied to the ground or roadbed in a liquid form. It is characterized in that it is sprayed together with a binder and compacted to form a heat insulating layer, and then a surface layer of asphalt, crushed stone, gravel, sand, concrete, etc. is formed thereon. This method has many advantages over the above-mentioned conventional construction methods in terms of frost heaving prevention performance and work efficiency.

In the present invention, as a material for forming the heat insulating layer, asbestos, rock wool, slag, glass wool, and cellulose fiber having water repellency and antiseptic properties are used singly or in combination of two or more. Asbestos is a natural mineral fiber represented by chrysotile. Rock wool is made from natural rock, while slag cotton is made by blending natural ore with iron slag, and both are made into fibers by melting them at high temperatures. Glass wool is a fiber made from glass raw material. On the other hand, cellulose fiber is a plant fiber such as crushed or defibrated pulp. Since the materials used in the present invention described above are all cotton-like, they can be used as heat insulating materials, and are particularly suitable for spraying because they can be blown through hollow piping.

In the present invention, a spraying machine is used to spray the cotton-like heat insulating material onto the roadbed or roadbed. still,
By spraying the liquid binder at the same time as spraying the heat insulating material and immediately compressing it, the heat insulating layer can be efficiently formed.

In this case, organic binders include asphalts such as straight asphalt and blown asphalt, rubber compounds such as natural rubber, butadiene rubber, butadiene styrene rubber, nitrile rubber, and chloroprene rubber, vinyl chloride, vinyl acetate, Examples include polyvinyl alcohol, polyvinyl compounds such as vinylidene chloride, acrylic compounds such as methacrylic acid and acrylic acid resins, cellulose compounds such as carboxymethyl cellulose and hydroxyethyl cellulose, phenolic resins, and unsaturated polyester resins.

Additionally, depending on the conditions at the construction site, prior to forming the heat insulating layer, measures may be taken to prevent moisture from entering from the surrounding area by using films, sheets, etc. on the bottom and surrounding surfaces of the dug-out ground, or by removing sand. It is desirable to correct unevenness on the bottom surface by laying it all over the place.

Use a road roller, vibrating compactor, etc. to compact the sprayed cotton-like insulation material. The heat insulating layer after compaction should be at least 1 cm thick, and when using bulky materials such as cellulose fiber or glass wool, it is desirable to compact the layer to a density that is three times or more when sprayed.

In the present invention, if a heat insulating material having water repellency and antiseptic properties is used, the frost heaving prevention effect can be maintained for a long period of time.

Therefore, when using cellulose fiber, it is desirable to subject it to water repellent treatment and antiseptic treatment.
In this case, the water repellent treatment involves treating the heat insulating material by dipping or spraying using an aqueous solution or dispersion of an organic silica compound, an organic fluorine compound, paraffin, zirconyl stearate, aluminum stearate, asphalt, etc. be. For antiseptic treatment, boron compounds, copper compounds, benzimidathiazole, creosote oil, tars, etc. are used.

Furthermore, in the present invention, a surface layer is formed on the above-mentioned heat insulating layer, and the surface layer herein refers to a paved portion such as a roadbed or surface layer made of asphalt, crushed stone, gravel, sand, concrete, etc. It is called
It can be formed using conventional construction methods.

As mentioned above, in the ground insulation method of the present invention, a cotton-like insulation material is sprayed together with a liquid binder to form a heat insulation layer, so molded boards of foamed resin are laid down, or foamed compositions are sprayed while foaming. There is no risk of leaving gaps or voids that could cause poor insulation. Moreover, since it is cotton-like, it is easily bonded by the entanglement of the fibers themselves, and does not require a large amount of binder unlike expanded polystyrene grains. In this way, the material's shape characteristics and heat insulation performance can be effectively utilized to provide excellent frost heaving prevention effects. Furthermore, by using a spraying machine, the work efficiency is much higher than that of conventional construction methods.

The present invention will be explained in detail with reference to Examples below.

Example 1 A water-repellent and antiseptic cellulose fiber blowing machine was used to spray cellulose fiber at an area density of 5 kg/m ² onto a roadbed dug 40 cm underground. At the same time, asphalt emulsion was sprayed onto the cellulose fiber at a solid content of 5%.
Thereafter, it was rolled with a road roller to form a 2 cm heat insulating layer. Crushed stone was spread on top of this and rolled with a road roller to form a 30cm thick layer of crushed stone, and the pavement was finished with asphalt. In addition, for the insulation test, the same cellulose fiber as above was sprayed to an areal density of 5 kg/m ² and then compressed to a thickness of 2 cm, and its thermal conductivity was measured.
It was 0.05kcal/mhr℃.

Example 2 Slag was used in place of cellulose fiber, the area density of spraying was 10 Kg/ ^m2 , butadiene styrene rubber was used in place of asphalt emulsion, and the thickness of the heat insulating layer after compaction was changed. Construction was carried out in the same manner as in Example 1 except that the thickness was 2.5 cm.

Example 3 In Example 1, rock wool was used instead of cellulose fiber, and the area density of spraying was 7 kg/
The construction was carried out in the same manner as in Example ¹ , except that the thickness of the heat insulating layer after rolling was 2 cm.

Example 4 Construction was carried out in the same manner as in Example 1, except that a mixture of cellulose fiber and mineral wool at a ratio of 7:3 was used.

In all of the above examples, construction workability was excellent. When excavated for sampling after 3 days of construction, no cracks were found in the heat insulating layer and the heat insulating performance was good.

Claims (1)

[Claims] 1. On the ground or roadbed, at least one flocculent material selected from asbestos, rock wool, mineral wool, glass wool, and cellulose fiber with water repellency and antiseptic properties is sprayed together with a liquid binder and compressed for insulation. A ground insulation method characterized by forming a layer and then forming a surface layer of asphalt, crushed stone, gravel, sand, concrete, etc.