JPH045317A - Civil engineering work method using foaming resin - Google Patents

Abstract

PURPOSE:To increase thickness and density in a foaming unit at its surface layer part and internal part by arranging a pipe in the ground, scattering a sand layer and a predetermined amount of foaming resin in the periphery of the pipe thereafter, coating it with a form, and applying a load to four corners and a central part of the form on the halfway of foaming work. CONSTITUTION:Foaming resin beads 5 are scattered on a sand layer 4 in the periphery of a pipe 3 after arranging it in the bottom of a hollow 2 on the original ground 1. A form 6 is arranged in a level equal to the surface of the ground 1. After the resin beads 5 are scattered in about 2.3cm thickness by using styrene resin of 0.9mm mean grain size, the pipe is covered by the form 6 of about 1mX1m size and 5cm in thickness. Next, steam of about 100 deg.C is blown from the pipe 3 at a flow rate of about 0.1m<3> per minute, and after 14min, a load 7 of about 20kg is uniformly applied respectively to four corners and the center of the mold form 6. In this way, thickness and density of the foaming unit at its surface layer part and internal part can be increased.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a civil engineering method for easily forming an artificial ground embankment 9, widening a road, etc. by foaming a foamable resin into a required shape on site.

[Conventional technology]

Attempts have been made to take advantage of the lightweight nature of foamed resin to fill depressions or use it as part of artificial ground. For example, foamable resin is molded into foam blocks of a predetermined shape in a factory, the foam blocks are piled up on the original ground that is to be embanked, and the surface layer is finished with concrete floor plates, wall protection materials, etc. Additionally, reinforcing materials such as reinforcing bars are placed inside to improve structural strength. When forming a foundation by stacking foams in this manner, misalignment is likely to occur between the foam blocks. Therefore, Japanese Utility Model Application Publication No. 81941/1986, Utility Model Application No. 63-81941,
In order to eliminate this misalignment, JP-A No. 81942 and the like introduces the method of forming irregularities on the surface of the foam block and interlocking the irregularities. However, the method of transporting foam blocks that have been foamed in a factory to the site and stacking them into a predetermined shape requires time and effort to transport and handle. For example, a large block of about 2XIX 0.5 m is used as this type of block, but such a large block requires manpower to transport, although it is lightweight. Furthermore, the transportation is essentially like transporting air, which is wasteful. Moreover, as the blocks become larger, it becomes necessary to flatten the original ground on which work such as embankment is to be performed so that no gaps are formed between the blocks and the laid blocks. Furthermore, Japanese Patent Application Laid-open No. 47-19617 discloses that after spraying an unfoamed resin such as urethane, vinyl chloride, or styrene onto a depression or roadbed, a foaming reaction is caused to fill the depression. ing. However, this publication does not specifically teach how to foam the resin. By the way, if the resin is simply foamed, the surface of the resin body after foaming often does not have the required contour due to non-uniform foaming or the like. In addition, when foaming occurs at the free interface,
The surface strength of the foam is insufficient, and dents are likely to occur when treading pressure is applied.

[Problem to be solved by the invention]

The inventors took advantage of the advantages of on-site construction. As a construction method to form the ground with the required strength, beads of foamed resin are scattered on the original ground separated by formwork.
We have developed a method for constructing the ground by foaming resin beads using heated gas. By the way, when constructing an artificial ground by foaming resin beads, if the foamed resin bodies are in the form of independent particles, the ground is likely to collapse when a large tread pressure is applied. On the other hand, it is known that lowering the expansion ratio improves the strength of the resulting resin foam. However, if the foaming ratio is excessively reduced, it will not be possible to fully utilize the advantage of foamed resin, which allows a large volume of ground to be constructed using a small amount of raw material. Therefore, the purpose of the present invention is to construct a foamed resin base with the required strength by applying pressure just before the end of the foaming reaction without substantially reducing the foaming ratio of the resin beads. shall be.

[Means to solve the problem] In order to achieve this objective, the civil engineering method of the present invention, when constructing the ground by foaming the foamable resin beads sprinkled on the original ground in the internal space of the formwork, immediately before the foaming reaction ends, It is characterized by pressurizing the beads. [For production]

In the present invention, beads of foamable resin are foamed in an internal space surrounded by a mold. After the heated gas such as water vapor injected into the formwork or beads is sufficiently used for the foaming reaction, it is released to the outside through the gap between the original soil and the formwork. Immediately before this foaming reaction ends, pressure is applied to the foamed resin beads. Due to the load at this time, the resin beads, which are still in a high temperature state, fuse together,
Strongly integrated. Various foamable resins used in the present invention are commercially available, such as styrene resins, phenol resins, urea resins, and urethane resins. Departure? N! Although the temperature is appropriately determined depending on the type of resin, a sufficient foaming reaction can normally proceed at about 70 to 200°C. *Ta,
The strength of the foam can be adjusted by changing the expansion ratio. The formwork that partitions the foaming atmosphere can be placed on the raw surface with a certain appropriate gap as long as the heated gas does not escape excessively. This formwork preferably has an internal space that is slightly smaller in volume than the volume obtained by foaming the resin in a free state, in order to apply appropriate pressure to the resin during foaming. The formwork can also be used in a state where it is buried as an oval member in the ground without being removed after the foaming reaction is completed. Alternatively, the foundation can be constructed by removing the formwork after foaming, scattering unfoamed resin beads thereon, and stacking foam layers in multiple stages. Further, the surface of the ground thus formed may be compacted using topsoil.

[Example 1] The present invention will be specifically explained below with reference to the drawings by way of an example applied to embankment of a depression. In this embodiment, as shown in FIG. 1, a predetermined embankment is placed in a depression 2 with a depth of 80 cm that has occurred in the original ground 1. At this time, the pipe 3 is arranged at the bottom of the depression 2, and the pipe 3 is
Fill the surrounding area with sand 4. Then, an appropriate amount of unfoamed styrene resin beads 5 are sprinkled on the sand layer 4. Next, the formwork 6 is placed at the same level as the ground level of the original ground 1 so as to cover the sand layer 4 and the #sn beads 5. Formwork 6
It is not necessary to seal the gap between the base and the original ground 1, and it is preferable that a slight gap be formed between the base and the original ground 1. As the resin beads, styrene resin with an average particle size of 0.9 mm was used. As shown in Figure 2, this resin starts a foaming reaction depending on the temperature and time, and at the end of the reaction it expands into a foam with an expansion ratio of about 30 to 45 times, and the density after foaming is about 0.015 g. /cm3. The effects of temperature and time on this foaming reaction are determined by the type of resin beads. The resin beads 5 were spread on the sand layer 4 to a thickness of 2.3 cm, and a concrete formwork 6 (weight 100 kg) having an area of 1 m x 1 m and a thickness of 5 cm was covered. Then, water vapor at a temperature of 100'C is pumped from pipe 3 every minute at 0.
．． The foaming reaction was carried out by blowing at a flow rate of 1 m3 for 15 minutes. During this foaming stage, 14 minutes after the start of steam injection.
After 5 minutes, a load 7 of 20 kg per location was applied equally to a total of 5 points in the center and four corners of the formwork 6. After the reaction was completed, the foamed resin filled the interior space of the depression 2 without any gaps. The foaming ratio at this time is approximately 35
It was double that. Moreover, the surface of the obtained foam was dense with foam particles integrally welded to each other. In contrast, the foam obtained without applying pressure during the later stages of the foaming reaction exhibited a surface layer with several cracks. Moreover, the inside of the foam was also thickened due to the weight of the mold and the pressurized atmosphere during foaming. The time to apply the load 7 is set after the time when the foaming reaction progresses somewhat rapidly as shown in the graph of FIG. This point in time is predetermined depending on the type of resin beads used. At this time, since the foamed resin is still in a high viscosity state at high temperature, the particles are easily fused together by pressurization. Depending on the magnitude of the load including the weight of the formwork 6, the degree of foaming of the foamed resin changes, which in turn changes the strength of the foam. FIG. 3 is a graph showing the effect of this load on the strength of the foam. The test was conducted at 20'C, 55
The strength was determined by the compressive stress value when applying a compressive strain of 4% to a 5OX50X50 mm test piece in an atmosphere of %RH. In addition, the strength of the surface layer was measured on a test piece cut 5 cm from the surface of the foam. As is clear from FIG. 3, the strength of the foam increases as the load increases. This compressive strength is determined by the stress generated under the pavement under normal traffic loads of 0.5k.
g/cm" or less, this indicates that the ground has sufficient treading strength.The magnitude of the load depends on the type of resin beads used. Although it cannot be generally specified, the desired effect can be obtained with a load of about 5 to 30 kg/cm2. Although a load is applied, the present invention is not limited to this.For example, by airtightly sealing between the material surface 1 and the formwork 6, and increasing the pressure of the steam injected into the depression 2, The foamed resin may be pressurized with this water vapor pressure.Furthermore, in the embodiment, the embankment of a depression is used as an example, but the present invention can be applied to the creation of sloped land, expansion of road width, etc. using a similar method. [Effects of the Invention] As explained above, in the present invention, when foaming resin beads is carried out on-site to construct the ground, by applying pressure to the resin before the end of the foaming reaction, The surface layer and interior of the foam are made thicker to improve its strength.Although the ground obtained in this way is lightweight,
It has sufficient strength to withstand the running of vehicles, etc. As a result, workability is significantly improved compared to the conventional construction method using foam blocks, and because the formed ground is lightweight, there is no foundation ground subsidence caused by embankment.
There will be no negative impact on surrounding structures. Furthermore, since the load on the side walls and the like is reduced, it becomes possible to protect the ground wall surface using a simple wall surface protection material.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the embodiment of the present invention, Fig. 2 is a graph showing the foaming state of resin beads in relation to temperature and time, and Fig. jI3 shows the strength of the foam in relation to load. This is a graph. 1... Original ground 2... Depression 3... Pipe 4... Sand layer 5... Resin beads 6.
...Formwork 7...Load

Claims (1)

[Claims] When constructing the ground by foaming the foamable resin beads scattered on the original ground in the internal space of the formwork, the foamed resin is characterized in that the beads are pressurized immediately before the foaming reaction ends. Civil engineering method.