JPH0827462A - Refilling material having fluidity - Google Patents

Abstract

PURPOSE:To obtain a refilling material effectively using surplus soil, capable of readily refilling even in a narrow place to be refilled and refilling in uniform and proper strength without compaction such as rolling. CONSTITUTION:This refilling material having fluidity is obtained by blending 30-70kg hydraulic substance comprising cement and fly ash in the blending ratio of 8:2-3:7 by weight with 1m<3> of slurry of surplus soil and water and has >=10cm flow value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid backfill material that uses excavated soil left over from civil engineering works, buried pipe works and the like.

[0002]

2. Description of the Related Art Unearthed soil produced during civil engineering work, burial work for sewer pipes and box culvert pipes generally contains various miscellaneous soils, and because of excavation, etc., soil strength is deteriorated. Cannot be used as a backfill material. For this reason, it has been attempted to use sand as a backfill material after mixing sand with excavated soil after adjusting the soil quality, but it is difficult to obtain high-quality sand and the treatment cost increases, so most of the soil is discarded. Abandoned in the field. However, recently, it has become difficult to secure a dumping site for the remaining soil, and therefore, after adjusting the soil quality by mixing cement and lime, or industrial waste such as inexpensive sludge incineration ash, with the excavated remaining soil. There are many cases of backfilling.

[0003]

Generally, when backfilling the residual soil mixed with a soil conditioner such as sand, compaction by compaction by water compaction or water tightening is indispensable, and if the compaction is not uniform, it causes collapse and industrial disposal. Even if an inexpensive material such as a material is used, there is a problem that the backfill cost eventually becomes high due to repair of the depression. In addition, there is a problem in that when the area to be backfilled is small, the work such as rolling compaction is restricted and cannot be carried out.

The present invention provides a fluidity backfilling material that solves the above-mentioned problems of the prior art. It effectively utilizes the residual soil and can be easily put in even when the location to be backfilled is narrow,
Moreover, it is an object of the present invention to provide a fluid backfilling material that can be uniformly backfilled without performing compaction such as rolling compaction.

[0005]

That is, according to the present invention, there is provided a fluid backfill material having the following constitution: (1) Cement: per 1 m ³ of slurry of residual soil and water:
The weight mixing ratio of fly ash (hereinafter, the weight mixing ratio is simply referred to as a mixing ratio) is 8: 2 to 3: 7.
A fluid backfill material with a flow value of 10 cm or more mixed with 0 to 70 kg. (2) The fluid backfill material as described in (1) above, wherein the residual soil is excavated residual soil. (3) The fluid backfill material according to (1) above, wherein the mixing ratio of cement: fly ash of the hydraulic material is 7: 3 to 5: 5. (4) The fluid backfill material according to (1) above, wherein the slurry has a flow value of 18 cm or more and a water content ratio of 80% or less.

[0006]

[Detailed Description] The present invention is a fluid backfill material obtained by blending residual soil with a hydraulic material made of a mixture of cement and fly ash and water. Excavation residual soil is generally used as the residual soil, and the following description uses the residual excavated soil as an example, but the scope of application of the present invention is not limited to the residual excavated soil. The present invention can be implemented as long as the soil has the same soil quality as the excavated soil.

The fluidity backfill material of the present invention has fluidity with a flow value of 10 cm or more measured by the cylinder method immediately after kneading so that it can be filled in the working area without any gap during backfilling. By the way, the flow value above 10 cm,
It has been empirically confirmed by the present inventors that if it is 12 cm or more, the backfilled portion will flow well under the pipe or into the narrowed portion and no void will be generated in the filled portion.

The method for making a slurry is not limited, but according to a method in which water is added to the residual soil to make a slurry, and a hydraulic material made of a mixture of cement and fly ash is mixed with the slurry, a fluidity having a desired flow value is obtained. It is preferable because a backfill material can be easily obtained. The amount of water to be added to the remaining soil is appropriately determined depending on the type of the remaining soil, the water content ratio, the particle size distribution, etc., the characteristics required for backfilling, the construction conditions, etc.

In the method of obtaining a fluid backfill material by adding water to the residual soil to form a slurry and then mixing the hydraulic material, water is added to the residual soil to form a slurry having a flow value of 18 cm or more, and a predetermined mixing ratio is added thereto. By mixing a predetermined amount of the hydraulic material described above, a backfill material having a flow value of 10 cm or more and having a high fluidity can be obtained. In this case, the water content of the slurry is 80
When it becomes larger than wt% (hereinafter, wt% is simply referred to as%),
Even if a predetermined amount of hydraulic material is added, breathing remarkably occurs, which is not preferable.

The fluidity backfilling material of the present invention contains a hydraulic material prepared by mixing cement and fly ash. The strength of the backfill material is secured by the hydration hardening action of cement. The mixing ratio of cement: fly ash (hereinafter referred to as S: FA ratio) is 8: 2 to 3: 7, preferably 7: 3 to 5: 5.

When cement alone and fly ash alone were blended, the fluidity immediately after kneading was relatively good, but the one using cement alone was immediately fluidized as the hydration reaction proceeded. This is not preferable, because the workability deteriorates sharply, the workability deteriorates, the breathing rate increases, and uniform backfilling becomes difficult. Furthermore, the long-term strength after the 28-day age does not improve. On the other hand, fly ash is a substance having a slow pozzolanic reaction, and the use of fly ash alone has slightly higher fluidity immediately after kneading than that of cement alone. This is because the particles of fly ash are finer and more spherical than the cement particles, so that they exert a bearing action. However, fly ash alone is not preferable because early strength development due to hydration hardening reaction like cement cannot be obtained and the strength of the backfill material becomes insufficient.

When a hydraulic material in which fly ash is mixed with cement is used and the S: FA ratio is in the range of 8: 2 to 3: 7, the flow value does not decrease even after 30 minutes of kneading and the flowability is reduced. Rich and low breathing rate. In particular, the breathing rate of a hydraulic material having an S: FA ratio of 7: 3 to 5: 5 is extremely low at 1% or less, which is the most preferable.

In the fluid backfill material of the present invention, the mixing amount of the hydraulic material is 30 per 1 m ³ of the slurry of the residual soil and the water.
~ 70 kg. When the compounding amount is less than 30 kg, the strength development is small, and when it exceeds 70 kg, the fluidity is lowered and the workability is deteriorated, which is not preferable.

[0014]

Examples of the present invention will be described below. It should be noted that the present embodiment is merely an example and does not limit the scope of the present invention. 1) Materials used: The materials used in this example are as follows. Remaining soil: Excavation remaining soil of Ariake silt Cement (S): Ordinary Portland cement Fly ash (FA): JIS standard equivalent water: Tap water 2) Test method: Water is added to the remaining soil to form a slurry with a specified water content ratio, and then cement A hydraulic material prepared by mixing a predetermined amount of ash and fly ash was added, and its flow value, breathing rate and uniaxial compressive strength were measured. The flow value was measured by the cylinder method among the consistency test methods of KODAN-305-1985.

3) Experimental Results Mixture 50 in which the mixing ratio of cement and fly ash was changed per 1 m ³ of the slurry of the residual soil and water in which the water content ratio was changed
FIG. 1 shows the breathing rate after 24 hours, even though kg was blended. Slurry of residual soil with water content of 75% and water 1m ³
FIG. 2 shows the relationship between the elapsed time after kneading and the flow value, although 50 kg of a mixture of cement and fly ash was blended. Slurry of residual soil and water with different water content ratio 1
FIG. 3 shows the flow value after 30 minutes of kneading, in which 50 kg of a mixture having a different mixing ratio of cement and fly ash was mixed per m ³ . Cement: fly ash = 7: 3 per 1 m ³ of slurry of residual soil with water content of 75% and water
FIG. 4 shows the relationship between the uniaxial compressive strength and the elapsed time after molding of the specimen of the hydraulic material of 20-80 kg. Cement: fly ash = 7: 3 hydraulic material 30-80 per 1 m ³ of a slurry of 75% water content and residual soil
FIG. 5 shows the relationship between the elapsed time after kneading and the flow value, although kg was blended.

As shown in FIG. 1, breathing occurs in a slurry having a water content of 60% only when fly ash alone is blended. A slurry with a water content of 75% has a high breathing ratio when cement alone and fly ash alone are mixed, and the S: FA ratio is 8: 2.
Breathing does not occur in the range of to 3: 7. Further, in a slurry having a water content ratio of 80%, the S: FA ratio is 7: 3 to 5: 5.
Within the range, the breathing rate is as low as 1% or less. On the other hand, the slurry having a water content ratio of 87% has a remarkably high breathing rate at any S: FA ratio. Therefore, the water content of the slurry is 80%
The following are appropriate:

As shown in FIG. 2, in the case where the cement alone is added to the slurry, the flow value is drastically decreased 10 to 30 minutes after the kneading and the fluidity is deteriorated, so that uniform backfilling cannot be performed. . On the other hand, the fly ash alone and the mixture of the mixture of cement and fly ash did not lower the flow value even after 30 minutes from kneading, and maintained good fluidity.

FIG. 3 shows that, in the case of a slurry having a water content of 70 to 80%, the flow rate of the slurry containing cement alone has a flow value at any water content as compared with the case of adding the mixture of cement and fly ash. descend. On the other hand, the fly ash alone and the mixture of the mixture of cement and fly ash show a flow value higher than that of the cement alone in any of the slurries having a water content ratio of 70 to 80%.

As described above, according to the results shown in FIGS. 1 to 3, the flow rate of the slurry obtained by adding the cement alone to the slurry sharply decreases after 30 minutes of kneading, and a backfill material having high fluidity is obtained. I can't. Fly ash alone and a mixture of cement and fly ash do not cause a decrease in fluidity like cement alone, but the S: FA ratio is 8 :.
Those outside the range of 2-3: 7 are not suitable because the breathing rate becomes high. On the other hand, the S: FA ratio is 8: 2 to
The 3: 7 hydraulic material has a low breathing rate, especially S:
Those having an FA ratio of 7: 3 to 5: 5 have a breathing rate of 1% or less. Therefore, as a backfill material having a high fluidity and a low breathing rate, a hydraulic material obtained by mixing fly ash with cement and having S:
An FA ratio of 8: 2 to 3: 7, preferably 7: 3 to 5: 5 is suitable.

According to FIG. 4, in any case, the strength of 2 hours to 28 days increases in proportion to the compounding amount of the hydraulic material. However, if the hydraulic material is 20 kg, the 28-day strength is 1 kgf /
It is less than cm ² and has insufficient strength as a backfill material.

On the other hand, according to FIG. 5, 80 kg of hydraulic material is used.
In the blended product, the flow value sharply decreases after 30 kneading. Therefore, from the results of FIGS. 4 and 5, it is appropriate that the mixing amount of the hydraulic material added to the slurry is ^{30 to} 70 kg per 1 m ³ of the slurry.

[0022]

INDUSTRIAL APPLICABILITY The fluidity backfilling material of the present invention is capable of effectively utilizing the residual soil, and even when the location to be backfilled is narrow, it has excellent fluidity and can be easily backfilled. Backfilling with uniform and moderate strength can be achieved without compaction.

[Brief description of drawings]

Fig. 1 Slurry of residual soil and water with different water content 1m ³
Fig. 5 is a graph showing the breathing rate after 24 hours when 50 kg of a mixture having different mixing ratios of cement and fly ash was blended.

[Fig. 2] 1 m ³ of slurry containing 75% water content and residual soil
A graph showing a relationship between the elapsed time after kneading and the flow value, although 50 kg of a mixture of cement and fly ash was blended.

FIG. 3 is a graph showing a flow value after 30 minutes of kneading, in which 50 kg of a mixture of cement and fly ash having a different mixing ratio was blended per 1 m ³ of a slurry of residual soil and water having a different water content ratio.

[Fig. 4] 1 m ³ of slurry of residual soil and water having a water content of 75%
A graph showing the relationship between the elapsed time after molding of the specimen and the uniaxial compressive strength of a mixture of 20-80 kg of cement: fly ash = 7: 3 hydraulic material.

FIG. 5: Slurry of residual soil with water content of 75% and water 1 m ³
A graph showing the relationship between the elapsed time after kneading and the flow value, although 30 to 80 kg of cement: fly ash = 7: 3 hydraulic material was blended.

Claims (4)

[Claims] 1. A flow value of 10 to 30 kg of a hydraulic material having a cement: fly ash weight mixing ratio of 8: 2 to 3: 7 per 1 m ³ of a slurry of residual soil and water.
Fluidity backfill material of cm or more. 2. The fluid backfill material according to claim 1, wherein the residual soil is excavated residual soil. 3. The fluid backfill material according to claim 1, wherein the hydraulic material cement: fly ash has a weight mixing ratio of 7: 3 to 5: 5. 4. The fluid backfill material according to claim 1, wherein the slurry has a flow value of 18 cm or more and a water content ratio of 80% or less.