JP2007023137A - Method for conditioning grain size of soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inexpensively conditioning the gain sizes of various soils and for fully utilizing surplus ready mixed concrete which currently gives rise to a serious problem. <P>SOLUTION: The method comprises mixing soil whose grain size is to be conditioned with that portion of a crushed product obtained by dehydrating and crushing ready mixed concrete sludge which has such a particle size that 5 to 100 mm particles account for 90 wt.% of the entire particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for improving the particle size of soil.

Conventionally, when a building is constructed on a soft ground or used as a road, the soft ground is removed and discarded. And the soil whose particle size and intensity are predetermined values was put in the place. The removed ones have been used for land reclamation.
However, due to the decrease in landfills, it has become difficult to dispose of such unnecessary soil, and various improvements to soft ground have been devised due to the fact that soil with excellent particle size and strength cannot be obtained at low cost. .

For example, there are methods of mixing cement and lime to solidify or improving strength. This is expensive. Moreover, it is not necessarily the purpose only to obtain the strength by curing, and it may be better not to harden.
A slight improvement in grain size may be sufficient for embankments and dikes.

  In addition, clay is water and clay and is not easy to transport. Furthermore, it is said that a liquefaction phenomenon is likely to occur when soil particles do not have an appropriate particle size distribution, for example, when the particle sizes are very uniform. Therefore, it is necessary to improve the particle size of such soil.

  Apart from this, the surplus of ready-mixed food is one of industrial waste and cannot be discarded as it is. Therefore, usually, after separating the aggregate and the like, it is naturally dried and treated as waste. This was very laborious and expensive. For example, all of the surplus of concrete mixer truck, washing water, etc. are included.

  Therefore, the surplus processing of the raw food is also a big problem.

  Thus, the present invention provides an effective utilization method for surplus raw kon which can improve the particle size of various soils at low cost and is currently a big problem.

  In view of the situation as described above, the present inventor has completed a method for improving the particle size of the soil of the present invention as a result of intensive studies. The feature of the present inventor is that 90 wt. It exists in the point which mixes the crushed material whose% is 5-100 mm (size as a grain) with the soil which should improve particle size.

Here, the raw consludge is obtained by removing aggregates (crushed stone and sand) from surplus concrete. Since this raw consludge is liquid (emulsified) as it is, it is dehydrated by a filter press or the like, further naturally dried and discarded.
Dehydration as used in the present invention refers to one or more actions such as water evaporation, forced removal by a filter press, etc., consumption by a hydration reaction, and the like.

  In the present invention, the dehydrated material is crushed. Here, the feature of the present invention is not to make it all powder or small particles but to make particles of various sizes of 5 to 100 mm. Preferably, it is desirable that the sizes of 5 to 10, 10 to 20, 20 to 30, and 30 to 40 are included to some extent.

  Such a particle size distribution is not constant because it varies depending on the particle size distribution and water content of the soil to be mixed (to be improved). For example, if there is only a lot of clay and the drainage is poor, mix a large one with an appropriate particle size distribution, and if the soil contains a lot of specific particles, avoid the size and mix a lot of the others. You can do that.

  In the present invention, after crushing, particles having a size of 5 to 100 mm are selected. Of course, since it is practically impossible to be 100% of this size, 90% or more needs to be in this size. The reason for this size is that such a large one is usually insufficient in the case of improving the particle size. The most necessary one is 5-40 mm, which is usually sufficient.

  For example, in the case of removing 40 mm or more, there is no need to remove the method unless 40 mm or more comes out from the crushing device. The method only needs to be passed through a 40 mm sieve. The method of crushing, that is, the degree of particle size of crushing is arbitrary, and may be determined according to the particle size distribution of the soil to be mixed, the purpose of use, and the like.

  Such crushing and sorting may be performed by a conventional crushing device, a sieve, or the like, and need not be special.

  Here, the soil whose particle size should be improved is the one with too much clay content and cannot be embanked, the one with too much moisture to be transported by truck, the other with too much gravel and the poor particle size distribution, etc. Any soil may be used as long as it has a problem with the particle size distribution.

  The mixing method and amount may be determined appropriately each time, and there is no numerical limitation. The present invention is new in that dehydrated raw consludge, which has been conventionally industrial waste, is crushed again and mixed with soil. As an example, 10-30 weight part is mixed with respect to 100 weight part of soil.

  Other than these may be added to the dehydration of the soil and the raw consludge and the mixing with the crushed material. For example, solidifying materials, pigments, other soils, and the like.

  Further, as a method for curing the green consludge, there is a method of passing the green consludge through a pipe wound with a cable capable of energizing the green consludge.

  This is because a magnetic field is generated through a cable (coil) through a current of 1 to 2 A and 100 to 12000 Hz, and sludge is passed through the magnetic field. By passing through such a magnetic field, although the reason is not clear, aggregation is promoted, and the water content is clearly reduced as compared with the case of dehydration by a conventional filter press. In the experiment, 100 to 12000 Hz was effective, but about 100 to 500 Hz was particularly preferable. Although the current value depends on the amount of sludge to flow, it may be 1 to 2 A in a normal case.

The method of winding the cable around the pipe is not particularly limited, but it may be wound several times to several tens of times (or more). One location or multiple locations may be used. The winding method may be a method of winding the cables almost in contact with each other, or a method of winding a little open.
The wound cable is connected to a frequency converter such as an inverter, a high-frequency current generator, or the like.
As such a generator, an AC 100V power source is used, and it is preferable that the frequency can be converted to a frequency of 100 to 12000 Hz, and the frequency can be automatically changed periodically or can be changed manually.

  That is, the frequency of the current sent to the cable may be constant or varied. Also, there are a method of changing the change gently and a method of changing it abruptly.

The method for improving the particle size of the soil of the present invention has the following effects.
(1) Waste treatment is reduced because raw consludge can be used effectively. This is a huge advantage for the concrete industry.
(2) Since the soil particle size can be improved, there are significant advantages such as compaction and prevention of liquefaction.
(3) Since the hardened components still remain in the dehydrated and crushed material of raw consludge, mixing this improves the strength of the soil and also has a water absorption effect, so that soil that cannot be transported by truck is It can be transported.
(4) In particular, in the method of dehydrating after passing through a tube in which a cable that can be energized is wound, the dehydration is fast, and a larger amount of the curing component remains.

  Hereinafter, based on an Example, this invention is demonstrated in detail.

Example 1
The dehydrated cake was produced by a filter press for producing ordinary dehydrated cake on the day of ordinary raw consludge. Its water content was about 25%. This was divided into appropriate sizes, put into a crusher and crushed. This crusher crushes to about 40 mm, and most of the crushed material is 50 mm or less. Of these, particles having a size of 5 to 40 mm were selected. The method was only selected with a 5 mm sieve remaining and falling with a 40 mm sieve. Therefore, the thing of 5-40 mm is contained appropriately.

20% of this was mixed with clayey soil. The mixture was sprayed on the soil surface and mixed with a stabilizer. With this alone, the surface particle size was improved.
In addition, about 20% of the dug up clay was mixed with a mixer and used as a completely new embankment, but there was no problem. The compaction was especially good.

  Next, another example of the present invention will be shown. FIG. 1 is a cross-sectional view schematically showing an apparatus used in the present invention. First, normal raw sludge 1 is stored in a storage tank 2. From here, it transfers to the adjustment tank 3 with the pump 4. FIG. A cable 6 capable of energizing the transfer pipe 5 is provided. Therefore, during the transfer from the storage tank 2 to the adjustment tank 3, it is affected variously by the high-frequency current. The sludge 7 is made into a dehydrated cake by a normal filter press 8.

  FIG. 2 is a detailed view of the cable 6. Although the cable 6 is wound around the pipe 5, it is wound not at one place but at a plurality of places. The cable 6 is connected to a high frequency current generator 9.

Next, the effective frequency of the energized current was examined. In the method, raw consludge that was passed through a pipe wound with a cable energized with currents of various frequencies was placed in a 1000 ml graduated cylinder, and the amount of sedimentation (in mm) was examined. The time is after 2 and 3 minutes.
Frequency (Hz) 2 minutes later 3 minutes later 50 4mm 6mm
100 6mm 14mm
700 7mm 12mm
1500 8mm 12mm
5000 6mm 10mm
10000 6mm 9mm
15000 4mm 6mm
No energization 4mm 6mm

  From the above results, it was found that there was an effect at about 100 to 12000 Hz.

It is sectional drawing which shows the outline | summary of the apparatus used for this invention. 3 is a detailed view of a cable 6. FIG.

Explanation of symbols

1 Raw consludge 1
2 Storage tank 3 Adjustment tank 4 Pump 5 Transfer pipe 6 Cable 7 Sludge 8 Filter press 9 High frequency current generator

Claims (4)

A method for improving the particle size of a soil, comprising mixing 90% by weight of the crushed dehydrated raw consludge with a size of 5 to 100 mm (size as a particle) into the soil to be improved in particle size. The method for improving the particle size of soil according to claim 1, wherein the dehydrated raw consludge is one in which an uncured cement remains. The method for improving the particle size of soil according to claim 1 or 2, wherein, when dewatering the raw consludge, the raw consludge is passed through a pipe wound with a cable that can be energized. The method for improving the particle size of soil according to claim 3, wherein the frequency of the energized current is 100 to 12000 Hz.

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