JP4011069B2 - Test method of bentonite content in bentonite mixed soil - Google Patents

Description

  The present invention relates to a method for testing the amount of bentonite in bentonite mixed soil, and more specifically, used as a soil impermeable layer in the construction of 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.

In the case of constructing industrial waste disposal sites and agricultural irrigation ponds, bentonite mixed soil has been increasingly used in recent years to ensure poor water permeability. Normally, bentonite mixed soil is produced by stirring and mixing with a mixer. However, when construction is performed, whether the locally generated soil and bentonite are uniformly mixed is regarded as the most important.
Therefore, it is required to quickly and accurately determine the amount of bentonite in the bentonite mixed soil at the site or in an adjacent test room, and to determine the uniformity of the bentonite mixed soil in the pre-construction stage.

  As a conventional method for measuring the mixing amount of bentonite, a methylene blue adsorption amount measuring method (JBAS-107-91) generally defined by the Japan Bentonite Industry Association has been used. This method utilizes the fact that montmorillonite, which is the main component of bentonite, and some minerals contained in soil adsorb methylene blue. However, this method requires a special instrument, takes time for measurement and pretreatment, and requires a skillful technique, so it is very difficult to perform measurement on site. Further, as other methods, there are methods for estimating in a relatively short time using viscosity, electrical conductivity, electrolyte, etc., but all of them require a measuring device and are not easy to manage (for example, , See Patent Literatures 1 to 4.)

On the other hand, there have been methods for obtaining the viscosity from a viscometer until now, but they are inferior in accuracy, are easily affected by the temperature at the time of measurement, and only take a relatively long time to measure (for example, (Refer nonpatent literature 1.).
JP-A-8-110290 JP-A-11-64206 JP 2000-346819 A JP 2001-4619 A Hiroki Kato et al. “Evaluation of the addition rate confirmation test of bentonite mixed soil” Proceedings of the 14th JSME Conference, 958-960, 2003

  The present invention has been made in view of the above problems of the conventional measurement method, and is not complicated in the laboratory or on-site, and the amount of bentonite mixed can be obtained quickly and accurately. It is an object of the present invention to provide a method for examining the amount of bentonite in a bentonite mixed soil which is not required.

As a result of studying to solve the above-mentioned problems, the present inventors have obtained a treatment of the suspension after the dispersion of the prepared bentonite mixed soil by utilizing the fact that the viscosity is expressed when the bentonite is dispersed in water. It was found that the amount of bentonite in the bentonite mixed soil can be verified from the flow time measured by a capillary viscometer using the obtained supernatant. 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, which is stirred at 300 to 500 rpm with a stirrer to disperse the bentonite mixed soil in water and has an opening of 0.1 mm to 0.5 The coarse particles in the soil particles are separated and removed through a sieve of mm, and the separated suspension is allowed to stand to separate into a supernatant liquid and a sedimented layer, and the supernatant liquid is allowed to flow down by a capillary viscometer. The bentonite mixed soil is characterized in that the bentonite mixed amount is measured by using a calibration curve of the flow-down time of the supernatant and the bentonite mixed amount prepared in advance. The method of testing the amount of bentonite in the
( 2 ) The method for assaying the amount of bentonite in the bentonite mixed soil according to (1 ), wherein the capillary viscometer has a capillary diameter of 0.5 mm to 1.75 mm ;
(3) The method for testing the amount of bentonite in the bentonite mixed soil according to (1) or (2), wherein the measured flow-down time is corrected by a correction coefficient relating to the liquid temperature. Is.

  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 mixed with the same high accuracy as the adsorption amount measurement method.

In the present invention, the bentonite mixed soil is dispersed in water, the coarse particles in the soil particles are separated through a sieve, separated into a suspension and a sedimented layer by standing, and a certain amount of the supernatant liquid flows down. The flow-down time is obtained, and the bentonite mixture amount is verified from the flow-down time. At this time , a test curve for the flow time and the bentonite mixture is prepared, and the amount of bentonite in the bentonite mixed soil is tested from the test curve. By the dispersion and sieving of the bentonite mixed soil, substantially all of the bentonite mixed in the mixed soil is contained in the supernatant.

  In the present invention, the soil mixed with bentonite is not particularly limited, and can be applied to, for example, locally generated soil at a construction site such as a general waste disposal site. 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 amount of the dispersion stabilizer added is preferably 0.03 to 0.2 mass% with respect to 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 assay method of the present invention is used is not particularly limited, but bentonite is preferably 25% by mass or less, and more preferably 3 to 20% by mass.
Moreover, there is no restriction | limiting in particular also in the ratio of the mixed soil at the time of disperse | distributing a bentonite mixed soil, It is preferable that water is 300-500 ml with respect to 100-300 g of mixed soil.
The time to disperse the bentonite mixed soil in the water, after the bentonite mixed soil is dispersed in the water, the sieve opening when removing coarse particles in the suspension by sieving, and the capillary viscometer capillary The diameter and the capacity of the capillary viscometer can be arbitrarily determined. The time for dispersing the bentonite mixed soil in water is preferably 5 to 15 minutes in the case of 150 g mixed soil and 300 ml water, for example. In this case, it stirred at 300~500rpm by stirrer.
The mesh of the sieve required to remove the coarse particles in the dispersion is 0 .1mm~0.5mm, more preferably through a sieve having a mesh opening 0.2 mm. In the case of sufficient time for separating the suspension that has passed through the sieve into a supernatant and a sedimented layer, for example, 150 g of the above mixed soil and 300 ml of water, it may be allowed to stand for 2 to 10 minutes.
There is no particular limitation on the capillary viscometer for measuring the flow-down time of the subsequent supernatant containing bentonite, but any vertical capillary viscometer is preferable, and among them, the Ostwald capillary viscometer is more preferable. The capillary viscometer preferably has a capillary diameter of 0.5 mm to 1.75 mm, more preferably 1.O mm to 1.5 mm. The length of the capillary is not particularly limited, but is preferably 50 to 100 mm.
The amount of the supernatant for measuring the flow-down time is not particularly limited, but is preferably 1 to 5 ml, more preferably 3 ml.
These measurement conditions are the same for the measurement for preparing the calibration curve and the measurement of the target mixed soil.

In the verification method of the present invention, complicated instruments are not required, and since there are no difficult operations, the occurrence of personal errors is reduced. Moreover, the assay method of the present invention is highly accurate and can also detect segregation of the bentonite content in the bentonite mixed soil.
Furthermore, measurement can be performed in a short time, and the amount of measurement sample can be increased. In addition, there is no limitation on the locally generated soil used, and even if there is gravel mixed 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 varies, the bentonite mixing amount is hardly affected, and even when the room temperature or the liquid temperature varies, the flow time can be easily corrected by the coefficient. For example, capillary diameter 1.0 mm, when using an Ostwald capillary viscometer capillary length 100 mm, a flow time t ¹⁵ of the liquid temperature 15 ° C., when the correction coefficient alpha, flow time at any temperature is represented as [alpha] t ¹⁵ be able to.
Table 1 below shows the correction coefficient α of the flow down time for a liquid temperature of 15 ° C.

Moreover, when calculating | requiring the test curve of the flow-down time and bentonite mixing amount performed previously in mixed soil, a test curve can be obtained by preparing mixed soil, stirring, sieving, standing, and measuring. .
Among these, preparation of mixed soil can be performed, for example, by adding bentonite to a locally generated soil and mixing it sufficiently. The set amount of bentonite may be, for example, a normal electronic balance. The locally 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 tap water in a stirrer, adding the sample of the above mixed soil, and stirring. After stirring, sieving is performed, coarse particles are removed, the mixture is allowed to stand, and the flow-down time of the specified amount of the supernatant liquid can be measured with a capillary viscometer. The measured flow-down time and bentonite mixture amount are regressed by a conventional method, and a test curve of the flow-down time and bentonite mixture amount can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited to this.
Example 1
Known bentonite mixture consisting of 6 mass%, 8 mass%, 10 mass%, 12 mass% and 15 mass% of bentonite (trade name Kunigel U, manufactured by Kunimine Industries Co., Ltd.) with respect to the soil (A) anhydrous weight The flow time of the soil supernatant was measured, and the test curve for the bentonite mixture and flow time was obtained.
The measurement was performed according to the flowchart shown in FIG. Specifically, 150 g of bentonite mixed soil having a known bentonite mixing amount was accurately measured using an electronic balance and put into a 1000 ml container containing 300 ml of tap water. Subsequently, the mixture was stirred and dispersed for 10 minutes at a rotation speed of the stirring blade of 350 rpm with a turbine-type stirring blade equipped with a stirring blade (three-one motor).
Thereafter, the dispersion was passed through a sieve having an opening of 0.2 mm, and the suspension was sufficiently stirred and allowed to stand for 2 minutes. 10 ml of the supernatant was collected and Ostwald capillary viscometer (capillary diameter 1.0 mm, capillary length 100 mm) ; Manufactured by SIBATA), and the flow time of 3 ml of the suspension was measured. The flow-down time was as shown in Table 2. FIG. 2 is a diagram showing a test curve obtained from the flow time and the amount of bentonite mixed. This test curve is represented by y = 0.2293 × ^1.2975 , R ² = 0.9726. X and y are the horizontal and vertical axes, respectively, and R is a correlation coefficient. (The same applies hereinafter).
FIG. 3 shows the particle size distribution of soil (A), and Table 3 shows the liquid / plastic limit and plastic index.
As is apparent from Table 2 and FIG. 2, it can be seen that there is a correlation between the bentonite mixing amount and the flow-down time, and the bentonite mixing amount can be tested from the flow-down time.

Example 2
The supernatant of a known bentonite mixed soil consisting of 6% by mass, 8% by mass, 10% by mass, 12% by mass and 15% by mass of bentonite (made by Kunimine Kogyo Co., Ltd., trade name Kunigel U) with respect to the anhydrous weight of the soil (B) The flow time of the liquid was measured, and the relationship between the amount of bentonite mixed and the flow time was determined.
The measurement procedure was the same as in Example 1. The values of the flow time obtained were as shown in Table 4. FIG. 4 shows a test curve obtained from the flow time and the bentonite mixing amount. The calibration curve is y = 0.0596x ^1.6934, represented by R ² = 0.9602.
FIG. 5 shows the particle size distribution of soil (B), and Table 5 shows the liquid / plastic limit and the plasticity index.
As is apparent from Table 4 and FIG. 4, it can be seen that there is a correlation between the bentonite mixing amount and the flow-down time, and the bentonite mixing amount can be verified from the flow-down time.

Example 3
The supernatant of a known bentonite mixed soil composed of 6% by mass, 8% by mass, 10% by mass, 12% by mass and 15% by mass of bentonite (trade name Kunigel U, manufactured by Kunimine Industries Co., Ltd.) with respect to the anhydrous weight of the soil (C) The flow time of the liquid was measured, and the relationship between the amount of bentonite and the flow time was determined.
The measurement procedure was the same as in Examples 1 and 2. The values of the flow time obtained were as shown in Table 6. FIG. 6 shows a test curve obtained from the flow time and the amount of bentonite mixed. The calibration curve is y = 0.0015x ^2.9241, represented by R ² = 0.9816.
FIG. 7 shows the particle size distribution of soil (C), and Table 7 shows the liquid / plastic limit and plastic index.
As is apparent from Table 6 and FIG. 6, it can be seen that there is a correlation between the bentonite mixing amount and the flow-down time, and the bentonite mixing amount can be verified from the flow-down time.

Example 4
Bentonite (Kunimine Kogyo Co., Ltd., trade name Kunigel U) content of 6 mass%, 8 mass%, 10 mass%, 12 mass% and 15 mass% of the known bentonite mixed soil with respect to the soil (A) For the suspension, the flow time was measured on the one hand, and the bentonite content was determined from the bentonite mixing amount and flow time calibration curve created in Example 1, and on the other hand, the methylene blue adsorption according to the above (JBAS-107-91) The amount of bentonite was determined by an amount measuring method.
Table 8 and FIG. 8 are a table and a graph showing the results obtained thereby, respectively.

As can be seen from Table 8 and FIG. 8, it can be seen that the value obtained by the conventional method for measuring the amount of adsorbed methylene blue and the value obtained by the present invention are substantially the same.
Example 5
A known bentonite mixed soil comprising bentonite (Kunimine Kogyo Co., Ltd., trade name Kunigel U) content of 6 mass%, 8 mass%, 10 mass%, 12 mass% and 15 mass% with respect to the soil (B) For the suspension, the flow time was measured on the one hand, and the bentonite content was determined from the bentonite mixture and the flow time calibration curve prepared in Example 2, and on the other hand, the methylene blue adsorption according to the above (JBAS-107-91) The amount of bentonite was determined by an amount measuring method.
Table 9 and FIG. 9 are a table and a graph showing the results obtained thereby, respectively.

As is apparent from Table 9 and FIG. 9, it can be seen that the value obtained by the methylene blue adsorption amount measurement method and the value obtained by the present invention are almost the same for soil (B).
Example 6
Bentonite (Kunimine Kogyo Co., Ltd., trade name Kunigel U) content of 6 mass%, 8 mass%, 10 mass%, 12 mass% and 15 mass% of the known bentonite mixed soil with respect to the soil (C) For the suspension, the flow time was measured on the one hand, and the bentonite amount was determined from the bentonite mixture amount and flow time calibration curve prepared in Example 3, and on the other hand, the methylene blue adsorption according to the above (JBAS-107-91) The amount of bentonite was determined by an amount measuring method.
Table 10 and FIG. 10 are a table and a graph showing the results obtained thereby, respectively.

  As is clear from Table 10 and FIG. 10, it can be seen that for soil (C), the value obtained by the methylene blue adsorption amount measurement method and the value obtained by the present invention are substantially the same.

FIG. 1 is a diagram showing a flowchart of the test method of the present invention in the embodiment. FIG. 2 is a diagram showing a test curve obtained in Example 1. FIG. FIG. 3 is a diagram showing the particle size distribution of the soil (A) used in Example 1. FIG. 4 is a diagram showing a test curve obtained in Example 2. FIG. 5 is a diagram showing the particle size distribution of the soil (B) used in Example 2. FIG. 6 is a diagram showing a test curve obtained in Example 3. FIG. 7 is a diagram showing the particle size distribution of the soil (C) used in Example 3. FIG. 8 is a diagram showing the relationship between the test amount of soil (A) by the test method of the present invention and the amount of bentonite determined by the methylene blue adsorption amount measurement method. FIG. 9 is a diagram showing the relationship between the test amount of soil (B) by the test method of the present invention and the amount of bentonite determined by the methylene blue adsorption amount measurement method. FIG. 10 is a diagram showing the relationship between the amount of assay for soil (C) by the assay method of the present invention and the amount of bentonite determined by the methylene blue adsorption amount measurement method.

Claims (3)

A method for testing the amount of bentonite in a bentonite mixed soil obtained by mixing soil and bentonite, which is stirred with a stirrer at 300 to 500 rpm to disperse the bentonite mixed soil in water, and has a sieve having an opening of 0.1 mm to 0.5 mm. When the coarse particles in the soil particles are separated and removed, the suspension after the separation is allowed to stand to separate into a supernatant and a sediment layer, and the supernatant is allowed to flow down by a certain amount with a capillary viscometer. The bentonite in the bentonite mixed soil is characterized by measuring the flow down time and verifying the bentonite mixed amount by the flow down time using a previously prepared calibration curve of the flow down time of the supernatant and the bentonite mixed amount. Quantity testing method. Assay method of claim 1 Bentonite amount of bentonite mixed soil, wherein the capillary diameter of the capillary viscometer is 0.5Mm～1.75Mm. 3. The test method for the amount of bentonite in the bentonite mixed soil according to claim 1 or 2, wherein the measured flow-down time is corrected by a correction coefficient relating to the liquid temperature.

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