JP4139787B2 - Test method of bentonite content in bentonite mixed soil - Google Patents

Description

  The present invention relates to a method for verifying the amount of bentonite in bentonite mixed soil, and more specifically, used as a soil impermeable layer in the construction of general industrial waste disposal sites, agricultural irrigation ponds, and scenic ponds such as golf courses, The present invention relates to a method for measuring and verifying the amount of bentonite mixed in bentonite mixed soil such as water-impervious structure soil mixed with locally generated soil.

  Bentonite mixed soil is frequently used in water-impervious constructions such as industrial waste disposal sites and agricultural irrigation ponds to ensure poor water permeability. The water-imperviousness of bentonite mixed soil depends on the amount of bentonite mixed, the water content and the compaction density. The most important point when using bentonite mixed with locally generated soil or the like is that the generated soil and bentonite must be uniformly mixed throughout the construction. It is desirable to prove that the bentonite mixed soil produced by stirring and mixing with a mixer is uniformly mixed before the completion of the formation of the water-impervious structure soil. However, since there is a risk of non-uniformity due to conditions at the construction site, etc., it is required to quickly and accurately determine the amount of bentonite in the bentonite mixed soil for production management and construction management of the bentonite mixed soil.

  Conventionally, as a method for measuring the amount of bentonite mixed, a methylene blue adsorption amount measuring method has generally been used. The methylene blue adsorption amount measurement method is based on the adsorption of methylene blue by montmorillonite, which is the main component mineral of bentonite, and some clay minerals contained in the soil. (JBAS-107-91) and has been widely used.

However, when testing the amount of bentonite mixed in the bentonite mixed soil using the methylene blue adsorption amount measurement method, this method takes time, and in the case of mixed soil mixed with relatively large particles of coarse sand or more, finely pulverized. In addition, it is also necessary to dry in advance.
In addition, an instrument is required for dispersion in the dispersion medium after sampling, and there is a point that skill is required in the measurement and the results are likely to vary. For this reason, there is a method of estimating in a relatively short time using viscosity, electrical conductivity, electrolyte, etc. using various measuring devices because it is not affected by the nature and particle size of the soil mixed with bentonite. However, a special measuring device is required, and it is easily affected by the temperature at the time of measurement and the soil generated in the field (for example, see Patent Documents 1 to 4). As described above, it has been difficult to measure the mixing rate quickly and accurately in a short time and at the place where the mixed soil is manufactured by the methods proposed so far.
JP-A-8-110290 JP-A-11-64206 JP 2000-346819 A JP 2001-4619 A

  The present invention has been made in view of the above circumstances, and aims to provide a method for examining the amount of bentonite in bentonite mixed soil that is quickly and accurately obtained and does not require skill or special equipment or chemicals. To do.

As a result of intensive investigations to solve the above problems, the present inventors made use of the fact that the water-imperviousness of bentonite is remarkably superior to that of general soil. It was found that the amount of bentonite in the bentonite mixed soil can be verified from the amount of filtered water using the. The present invention has been made based on this finding.
That is, the present invention
(1) A method for testing the amount of bentonite in a bentonite mixed soil obtained by mixing soil and bentonite, wherein the bentonite mixed soil is dispersed in water and allowed to stand to separate into a suspension and a precipitate layer. The amount of filtered water when it is filtered for a certain period of time, and the amount of bentonite mixed soil is verified from the amount of filtered water,
(2) A calibration curve for the amount of filtered water and the amount of bentonite mixed is prepared, and the method for testing the amount of bentonite in the bentonite mixed soil according to (1),
(3) Provided is a method for testing the amount of bentonite in bentonite mixed soil according to (1) or (2), wherein the filtration is performed at a pressure of 0.5 to 5 kg / cm ² .

  The assay method of the present invention, although the conventional methylene blue adsorption amount measurement method has high measurement accuracy, requires special skill and skill, and takes time. It is possible to test the amount of bentonite admixture with the same high accuracy as the adsorption amount measurement method.

  In the present invention, bentonite mixed soil is dispersed in water, separated into a suspension and a precipitate layer by standing, the amount of filtrate when the suspension is filtered for a certain period of time is determined, and the amount of bentonite mixed is verified from the amount of filtered water. To do. Preferably, a test curve for the amount of filtered water and the amount of bentonite mixed is prepared, and the amount of bentonite in the bentonite mixed soil is tested from the above test curve. By dispersing and standing the bentonite mixed soil, substantially all bentonite mixed in the mixed soil is contained in the suspension.

  In the present invention, the soil mixed with bentonite is not particularly limited. For example, the soil generated locally at a construction site such as a general industrial waste disposal site, an agricultural irrigation pond, and a scenic pond such as a golf course. Applicable. When the bentonite mixed soil is made with locally generated soil and bentonite at the site of preparation, the amount of bentonite mixed in the bentonite mixed soil is measured quickly and reliably at the site or in an adjacent test room, etc. The uniformity of the mixed soil can be tested and managed, and the reliability of the bentonite mixed soil as a structure can be improved.

  When the bentonite mixed soil is dispersed in water, a dispersion stabilizer such as sodium hexametaphosphate, sodium pyrophosphate or sodium polyacrylate may be added to the water. The addition of this dispersion stabilizer is effective for bentonite mixed soil which is difficult to disperse.

The amount of bentonite mixed in the bentonite mixed soil in which the method of the present invention is used is not particularly limited, but bentonite is preferably 25% by weight or less, more preferably 3 to 20% by weight.
Also, the ratio of the mixed soil and water when dispersing the bentonite mixed soil is not particularly limited, but water is preferably 300 to 500 ml with respect to 50 g of the mixed soil. The bentonite mixed soil is dispersed in water. The time, the pressure filtration time of the suspension, and the pressure of pressurization can be arbitrarily determined. For example, in the case of 50 g of mixed soil and 300 ml of water, the time for dispersing the bentonite mixed soil in water is preferably 5 to 10 minutes. At this time, it is preferable to stir at 300-500 rpm with a stirrer. It is sufficient that the dispersion is allowed to stand for 2 to 10 minutes for a sufficient time to separate into a suspension and a precipitate layer, for example, in the case of 50 g of the above mixed soil and 300 ml of water.
In the filtration of a suspension containing the subsequent bentonite, pressure is preferably carried out at 0.5 to 5 kg / cm ^2, more preferably 0.5~3kg / cm ^2. The time is preferably 5 to 15 minutes. These measurement conditions are the same for the measurement for preparing the calibration curve and the measurement of the target mixed soil.
Moreover, as a filtration apparatus, any thing can be used if it is equipped with a container, packing, and filter paper. For example, a normal pressurizable dehydration tester can be used. Moreover, 4 types, 5 types B, 5 types C, and 6 types based on JIS P3801 are preferable.
What is necessary is just to measure the amount of filtered water, for example using a general graduated cylinder.

In the method of the present invention, complicated instruments are not required, and since there are no difficult operations, the occurrence of personal errors is reduced.
In addition, measurement can be performed in a short time, and the amount of measurement sample can be increased. Also, there is no limitation on the soil generated in the field, and even if there is gravel contamination in the actual mixed soil, it can be measured without drying or crushing, unlike the method for measuring the amount of adsorbed methylene blue. Furthermore, even if the moisture content of the locally generated soil fluctuates, the bentonite mixing amount is hardly affected.

Moreover, when calculating | requiring the test curve of the amount of filtrate water and bentonite mixing in the mixed soil performed previously, a test curve can be obtained by producing mixed soil, stirring, leaving still, and measuring.
Among these, preparation of mixed soil can be performed, for example, by adding bentonite to the site-generated soil in a set blending amount and sufficiently mixing. The set amount of bentonite may be, for example, a normal electronic balance. The on-site generated soil and bentonite can be mixed by, for example, putting the amount measured with an electronic balance into a plastic bag or the like and vibrating.
Further, the stirring may be performed by, for example, setting a container containing distilled water in a stirrer, charging the sample of the above mixed soil, and stirring. After stirring, the mixture is allowed to stand for a certain period of time, and the supernatant liquid (suspension) is almost entirely put into a cell, set in a dehydration tester, pressurized at a constant pressure, and the amount of filtered water can be measured. The measured amount of filtered water and the amount of bentonite mixed can be regressed by a normal method to obtain a test curve between the amount of filtered water and the amount of bentonite mixed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.

Example 1
Known bentonite mixture comprising 3% by weight, 5% by weight, 7% by weight, 10% by weight, 15% by weight and 20% by weight of bentonite (Kunimine V2 manufactured by Kunimine Industry Co., Ltd.) with respect to the soil (A) The amount of pressure filtered water of the soil suspension was measured, and a test curve for the amount of bentonite mixed and the amount of filtered water was determined.
The measurement was performed according to the flowchart shown in FIG. Specifically, 50 g of bentonite mixed soil with a known bentonite mixing amount was accurately measured using an electronic balance and put into a 1000 ml container containing 300 ml of distilled water. Then, it stirred and disperse | distributed for 10 minutes with the rotation speed of 300 rpm of the stirring blade with the turbine type stirrer with a stirring blade (three one motor).
Thereafter, the mixture was allowed to stand for 2 minutes, and the suspension was collected in almost the entire cell and set in a filtration tester (fan filter press Model 12BL: manufactured by FANN Instrument Company). The amount of filtrate which flowed out under pressure for 10 minutes at a pressure of 1 kg / cm ² was determined. The amount of filtered water was as shown in Table 1. FIG. 2 shows a test curve obtained from the amount of filtered water and the amount of bentonite mixed. Moreover, the particle size distribution of soil (A) is shown in FIG.

Example 2
Known bentonite mixture comprising 3% by weight, 5% by weight, 7% by weight, 10% by weight, 15% by weight and 20% by weight of bentonite (Kunimine Industry Co., Ltd., Kunigel V2) with respect to the soil (B) The amount of pressure filtered water in the soil suspension was measured, and the relationship between the amount of bentonite mixed and the amount of filtered water was determined.
The measurement procedure was the same as in Example 1. The value of the amount of filtrate obtained was as shown in Table 2. FIG. 4 shows a test curve obtained from the filtered water amount and the bentonite mixed amount. Moreover, the particle size distribution of soil (B) is shown in FIG.

Example 3
Known bentonite mixture comprising 3% by weight, 5% by weight, 7% by weight, 10% by weight, 15% by weight and 20% by weight of bentonite (Kunimine Industry Co., Ltd., Kunigel V2) with respect to the soil (B) The amount of pressure filtered water in the suspension of the soil was measured, and the amount of bentonite determined in the test curve of the amount of bentonite mixed and the amount of filtered water prepared in Example 2, and methylene blue adsorption according to the above (JBAS-107-91) Table 3 and FIG. 6 show the relationship between the amount of bentonite determined by the amount measuring method.

  Table 3 and FIG. 6 show that the values obtained by the methylene blue adsorption amount measuring method, which is a standard method often used in the past, are almost the same as the values obtained by the present invention.

It is a flowchart of the test | inspection method in an Example. FIG. 3 is a diagram showing a test curve obtained in Example 1. It is a figure which shows the particle size distribution of the soil (A) used in Example 1. FIG. 6 is a diagram showing a test curve obtained in Example 2. FIG. It is a figure which shows the particle size distribution of the soil (B) used in Example 2. FIG. It is a figure which shows the relationship of the amount of bentonite calculated | required with the test amount by the method of this invention, and the methylene blue adsorption amount measuring method.

Claims (3)

  A method for testing the amount of bentonite in a bentonite mixed soil obtained by mixing soil and bentonite, wherein the bentonite mixed soil is dispersed in water and allowed to stand to separate into a suspension and a precipitate layer, and the suspension is separated for a certain period of time. A method for verifying the amount of bentonite in a bentonite mixed soil, wherein the amount of filtered water is determined and the amount of bentonite mixed is determined from the amount of filtered water.   The test method of the bentonite amount in the bentonite mixed soil according to claim 1, wherein a test curve of the filtered water amount and the bentonite mixed amount is prepared. The method of assay according to claim 1 or 2 Bentonite amount of bentonite mixed soil wherein said filtration is performed at a pressure 0.5 to 5 kg / cm ^2.

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