JPS6238399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses natural organic polymers and modified products thereof, such as carboxymethyl cellulose (CMC), carboxymethyl starch (CMS), and gum tragacanth, in the foundation work of civil engineering and construction works. This invention relates to an anti-corrosion agent for polymer muddy water used in the muddy method of excavating the ground using muddy water.

Conventionally, this method has used so-called bentonite slurry, which is made by suspending bentonite in water along with other additives during ground excavation.

However, in recent years, there has been a shortage of bentonite, and there has been an urgent need to develop a substitute. This polymer slurry was developed as a substitute for bentonite, which has the characteristics of high swelling, fine particle size, and base exchangeability.

However, some of the characteristics of this polymer mud are due to the characteristics of the soil particle/polymer composite, which is a combination of soil particles and polymer.
It was found that this is fundamentally different from bentonite mud, which does not interact significantly with soil particles. For example, (1) about 5% of excavated soil is mixed into muddy water in the field, but in polymer muddy water, the wall-building property is significantly improved by the addition of a small amount of soil; (2) the construction property of polymeric muddy water is Wall properties are controlled by the polymer concentration and the ratio of the amount of mixed soil to the polymer concentration, and the amount of water removed also changes depending on the ratio of the polymer concentration. (3) Although the wall-building properties of polymer muds deteriorate due to the inclusion of cement, they do not gel like bentonite muds. Polymer mud has higher cement resistance than bentonite mud, and the cement resistance is controlled by the ratio of polymer to mixed excavated soil. However, (4) if polymer mud is left for a long period of time, its wall-forming properties and viscosity decrease and its quality changes. This alteration is remarkable at high temperatures, and the more soil is mixed in.
The cause of this is mainly due to the hydrolysis of polymers by the enzymatic action of microorganisms in the contaminated soil.
Deterioration can be prevented by adding a deterioration inhibitor. (5) The wall-building properties, cement resistance, and alteration resistance of polymer mud are all controlled by the proportion of polymer and excavated soil particles in the mud.
This suggests that the properties of the polymer mud are related to the properties of the soil particle/polymer composite, especially the thickness of the polymer coating layer.

Among the properties of polymer mud described above, the alteration of mud water, which can be called a drawback, will be described in more detail. In this construction method, the borehole is filled with this polymer muddy water, and after the completion of excavation, the muddy water is collected during concrete pouring and stored in a mud storage tank. This muddy water is reused when drilling the next hole and can be used repeatedly (although the number of times the muddy water is diverted is more than twice that of bentonite muddy water). At construction sites, muddy water has a dark tinge, gives off a putrid odor, and the performance of the muddy water, such as its ability to form mud walls and viscosity, has deteriorated.
(However, no noticeable deterioration was observed during the construction period at sites where construction was carried out from autumn to winter.) This means that, especially at high temperatures, the polymers in the soil particle-polymer complex are released by enzyme action as the mud water is stored for several days. This suggests that the molecular weight has been reduced, and it is presumed that a type of hydrolysis is occurring. It is thought that the enzyme is induced and produced by microorganisms such as bacteria in the air or contaminated soil in the presence of a polymer such as glucan as a substrate.

So far, salicylic acid has been known as an effective deterioration prevention agent for this polymer mud (according to Japanese Patent Application Laid-Open No. 125510/1983), but depending on the type of soil mixed in and the season, it may reduce the grain size of the mud, Phenomena that appeared to be alteration were observed, such as an increase in the number of viable bacteria in the muddy water.

Therefore, the present inventors investigated various deterioration prevention agents that exhibit stronger effects regardless of the type of mixed soil or the season, and found that hexahydro-1,3,5-tris-(2-hydroxyethyl)- s-triazine,
1,2-benzisothiazolin-3-one, and 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.
The present inventors have completed the invention of a preservative for muddy water construction methods, which is characterized in that it is one or more active ingredients in a mixture with 3-one. We have discovered that rot can be suppressed by adding these compounds when preparing polymer slurry (mixing and stirring CMC, granular soil, and water). The concentration of preservative added is
It is sufficient to add 0.01% or more.

When these chemicals are used, workability is extremely good without impairing the functions of muddy water (viscosity, number of viable bacteria, etc.).

Next, the gist of the present invention will be explained using examples.

1 Example of viable bacteria count measurement test Γ Sterile pipette Γ Sterile shear dish Γ Sterile dilution water (distilled water) Γ Culture medium: Glucose bouillon agar medium (PH
7)...Sterilized by autoclave.

Prepare the above items and dilute the sample solution appropriately with the pipette and dilution water. Transfer 1 ml of the diluted solution to a petri dish, add the culture medium cooled to around 40°C, and stir well to solidify.

After culturing at 37°C for 2 days, count the colonies that have developed on the shears and multiply by the dilution factor to obtain the number of viable bacteria.

2. Viscosity measurement test example Place the sample solution in a constant temperature bath at 28°C and measure using a rotational viscometer.

Example 1 0.5% CMC and 5% wet soil were added as polymers, water was added, and the mixture was sufficiently dissolved in a mixer until no joint powder was found. To this was added 0.03% hexahydro-1,3,5-tris(2-hydroxyethyl)-s-triazine as a deterioration inhibitor, and the mixture was stored at 28°C. The state of decay of muddy water during storage is examined by changes in the number of viable bacteria and viscosity over time.

Example 2 Other drugs include 1,2-benzisothiazolone-3-one 0.01% and 0.04%.

5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-
Mixtures with 3-one 0.01%, 0.02%, and examples of combinations of these drugs include hexahydro-1,
3,5-tris(2-hydroxyethyl)-s-
Similar tests were conducted with 0.015% triazine and 0.005% 1,2-benzisothiazolone-3-one.

Comparative Example As a control, a test was conducted using a sample containing 0.05% salicylic acid.

From FIG. 1 and FIG. 2, it can be seen that the preservatives of the present invention, when added in extremely small amounts, can suppress spoilage of polymer slurry and prevent a decrease in viscosity.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphical representations of the results obtained in Examples and Comparative Examples of the present invention. The horizontal axis in Figure 1 shows the number of days that have passed (days), the vertical axis shows the number of viable bacteria (cells/ml), and the horizontal axis in Figure 2 shows the number of days that have passed (days), and the vertical axis shows the viscosity (cp). show. In Figure 1, Γ-Γ: When the preservative of the present invention described in Examples 1 and 2 is added at a predetermined concentration; ●-●: When 0.05% salicylic acid is added; and ●...●: When no addition is made. . In Figure 2, Γ-Γ: 0.03% hexahydro-1,3,5-tris(2-hydroxyethyl)-s-triazine, □-□: 0.01% 1,2-benzisothiazolone-3-one, □... □: 0.04% 1,2-benzisothiazolone-3-one, △-△: 0.01% and 0.02% 5-chloro-2
-Methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazoline-
Mixture with 3-one, ×−×: 0.015% hexahydro-1,3,5-
tris(2-hydroxyethyl)-s-
A mixture of triazine and 0.005% 1,2-benzisothiazolone-3-one, ●-●: the case where 0.05% salicylic acid was added, and ●...●: the case without addition.

Claims (1)

[Claims] 1 hexahydro-1,3,5-tris(2-hydroxyethyl)-s-triazine, 1,2-benzisothiazolone-3-one, and 5-chloro-2-methyl-4-isothiazolin-3-one and 2 - A preservative for muddy water construction, characterized in that the active ingredient is one or more of a mixture with methyl-4-isothiazolin-3-one.