JP2529785B2 - Hydrous soil improver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-containing soil conditioner. For details, improve the soil quality of construction surplus soil (hereinafter referred to as "remaining soil") that accompanies construction and civil engineering, etc.
The present invention relates to a water-containing soil improver suitable for reuse as a resource.

[0002]

2. Description of the Related Art Conventionally, most of the soil left in various places is
Although it cannot be reused, it is disposed of in landfills or taken to other places, but due to considerable illegal dumping, it has been highlighted as a problem of environmental destruction. This is because the amount of residual soil is increasing rapidly due to active redevelopment projects, etc., while landfill work is decreasing, making it difficult to secure a place to receive residual soil.

In addition, for backfilling the dug up site,
It is legally required to use sand. Therefore, in general, it is necessary to bring sand and sand from other places for backfilling, and the problem of environmental destruction is also occurring here. Regarding the reuse of the residual soil generated in such a situation, there is an example in which a test plant for the residual soil treatment using quick lime is operated.

[0004]

The method of the test plant described above is intended only for high-quality residual soil, and is improved for the residual soil with sun-dried and low water content because the site is vast. When considering an improved plant, since the site cannot be large, it is necessary to improve the residual soil generated at the site with a high water content without drying it in the sun, and such soil with a high water content has a large stickiness. However, there is a problem in that it adheres to a mixer or the like and is difficult to operate and cannot be processed.

[0005]

Means for Solving the Problems The inventors of the present invention have made diligent studies to solve the problems of the prior art and obtain an excellent improving agent for reusing the residual soil, and as a result, (meth) acrylic acid or a salt thereof was contained. The present inventors have found that by using a water-soluble polymer having a carboxyl group, such as a (meth) acrylamide-based polymer, and lime in combination, water-containing soil such as residual soil can be reused for backfilling, and arrived at the present invention.

[0006] That is, the gist of the present invention lies in a water-containing soil improver comprising a water-soluble polymer having a carboxyl group and lime. Hereinafter, the present invention will be described in detail. The improvement of the present invention is to reuse soft or highly tacky water-containing soil for backfilling, etc., while improving the strength, it imparts fluidity like sand, and to the extent that it does not swell in water. It is to solidify. Therefore, the improvement in the present invention does not mean that the water-containing soil is simply solidified in a solid state to lose fluidity.

The water-soluble polymer used in the present invention is usually a polymer which dissolves in 1 g or more in at least 100 ml of water. The polymer has a carboxyl group as a hydrophilic group, and among all the monomers constituting the polymer,
The monomer having a carboxyl group is usually contained in an amount of 1 to 80 mol%, preferably 5 to 60 mol%. In addition, the carboxyl group may be present in either free acid or salt form.

Examples of the salt include salts of alkali metals such as sodium and potassium, salts of alkaline earth metals such as calcium and magnesium, ammonium salts, amine salts such as alkylamines having 1 to 18 carbon atoms and alkanolamines. , And a mixture of two or more thereof, but an alkali metal salt is preferable. Examples of such water-soluble polymers include (meth) acrylic acid-based polymers containing (meth) acrylic acid or salts thereof, copolymers of maleic acid or its salts with vinyl acetate, itaconic acid or its salts, and (meth) Although there are copolymers with acrylamide, etc., a (meth) acrylamide polymer containing (meth) acrylic acid or a salt thereof is preferable. Examples of the acrylamide polymer containing (meth) acrylic acid or a salt thereof include those obtained by copolymerizing (meth) acrylic acid or a salt thereof with (meth) acrylamide, and partially hydrolyzing a polymer of (meth) acrylamide. It may be one. Further, a copolymer obtained by combining the above-mentioned monomers may be used.

Further, in the above polymer, a monomer containing a sulfonic acid group as a hydrophilic group, such as vinyl sulfonic acid,
It may be a copolymer containing allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof. Further, a hydrophobic monomer such as an olefin, an acrylic acid ester, or a vinyl ester may be contained as long as it does not impair the water solubility.

The molecular weight of the water-soluble polymer used in the present invention is usually 1,000,000 or more, preferably 5,000,000 or more. Although the production method is not particularly limited, it is generally a radical polymerization method, of which solution polymerization using water or a lower alcohol as a solvent is particularly adopted. The concentration of the monomer is usually 10% by weight or more, preferably 15 to 60% by weight. When the polymerization is carried out in an aqueous solvent, the polymerization initiator is a peroxide such as potassium persulfate or ammonium persulfate, and a redox-based initiator using them, N, N′-azobis-
Water-soluble radical polymerization initiators such as (2-amidinopropane) dihydrochloride and 4,4'-azobis- (4-cyanovalerate) -2-sodium are preferable. The amount of the radical polymerization initiator used is usually 0.005 to 5% by weight, preferably 0.05, based on the weight of the copolymerizable monomer mixture.
~ 0.5% by weight.

The polymerization method is not particularly limited, but if an aqueous solution polymerization is exemplified, a method of polymerization with stirring, a method of polymerization in an adiabatic state by leaving it in a container, a method of polymerization while removing heat in a sheet form, in oil A method of polymerizing in an aqueous emulsion or dispersion state is exemplified. As a method of standing and polymerizing, after removing oxygen through a predetermined monomer aqueous solution through nitrogen gas, a predetermined temperature and no radical polymerization initiator are added and uniformly mixed, then under a nitrogen gas stream, at a predetermined temperature. A holding method is exemplified. The polymerization temperature is usually selected in the range of 10 to 150 ° C. according to the molecular weight of the desired polymer, but is preferably 40 to 80 ° C.

The polymer thus obtained is directly dried in a drier or treated with a dehydrating agent, dried and pulverized before being used as a sample. The lime used in the present invention is quick lime or slaked lime, and in any case, it is preferably added as a powder. The mixing weight ratio of water-soluble polymer and lime is usually 1:
It is 1 to 1: 500, preferably 1: 2 to 1: 250.

The soil to which the present invention is applied is usually a soil having a water content ratio of 20% or more. In particular, the use of the improving agent of the present invention can be expected in soil having a high water content of 40 to 200 % , and further 60 to 150 % of water content. It is the residual soil (construction residual soil) that accompanies general civil engineering and construction work such as road construction and residential land development. The water content ratio is a ratio of the mass of soil water lost by oven drying at 110 ° C. to the oven dry mass of soil, which is expressed as a percentage, according to JIS A1203.
It is a value measured by (water content test method).

The soil includes loam layer, gravel, sand and the like, which is usually a mixture of these, but concrete fragments may be mixed depending on the site of occurrence. Since the water content depends on the soil type, it depends largely on the site where the water is generated. The one having a high water content ratio is, for example, the Kanto loam layer, which usually has a water content ratio of about 100 to 120 % and has high tackiness, but is solidified and granulated by using the improving agent of the present invention. Fluidity is imparted, there is no adhesiveness and no swelling in water, the ground support capacity is improved, and backfilling can be reused.

The amount of the improving agent of the present invention added is not particularly limited because it varies depending on the water content of the treated soil, but the water-soluble polymer is usually 0.001 to 1% by weight based on the water-containing soil,
It is preferably 0.01 to 0.5% by weight, and the amount of lime is
It is usually 0.2 to 20% by weight, preferably 0.5 to 10% by weight. The method of adding the improving agent of the present invention is not particularly limited, but it is preferably a method of adding lime after adding the water-soluble polymer, but it does not matter at all even if it is used by addition mixing or premixing. In addition, the mixing with the soil is carried out by a usual method, for example, a method of spraying the improving agent on the water-containing soil on a belt conveyor and mixing with a backhoe. Lime is usually added as a powder, but the water-soluble polymer may be added in the form of powder or an aqueous solution.

In the improving agent of the present invention, other cement-based solidifying agents, superabsorbent resins and the like can be added in any proportions, and these may be added separately during soil mixing.

[0017]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Production Example of Water-Soluble Polymer 9.60 g of 20 wt% sodium acrylate (hereinafter abbreviated as “ACA-Na”) aqueous solution and 13.60 g of water in a 100 ml separable flask equipped with a stirrer, a nitrogen introducing tube, and a cooling tube.
08 g of acrylamide (hereinafter abbreviated as “AAM”) and 32.82 g of demineralized water were added and uniformly dissolved. The system was degassed while introducing nitrogen into the container while stirring.

Next, the inside temperature is 50 ° C. by immersing in a 50 ° C. water bath.
Then, 4.50 g of 0.2 wt% N, N'-azobis- (2-amidinopropane) .dihydrochloride aqueous solution was added to bring the total amount to 60 g. The stirring was stopped when the polymerization was started. While introducing nitrogen, 4 in a constant temperature water bath at 50 ° C
When polymerized for a time, the polymer concentration was 25% by weight of A
Polymer A having a molar ratio of CA-Na / AAM = 10/90 was obtained.

Polymers B to H were obtained in the same manner except that the monomer composition was changed to that described below. Each of the obtained 25% by weight polymer was left with about 10 g for measuring the polymerization rate, wet-ground and dehydrated in acetone or methanol, dried under reduced pressure at room temperature, and further ground by a coffee mill grinder to obtain fine powder. did.

The polymerization rates measured by the bromine method were all about 100%. Also, regarding the reduced viscosity ηsp / c,
The dried polymer was dissolved in 1 N saline to a concentration of 0.1 g / dl and measured at 25 ° C. using an Ostwald viscometer. The monomer composition (molar ratio) and the reduced viscosity of the polymers A to H are shown below. (Composition) (Reduced viscosity) Polymer A: ACA-Na / AAM = 10/90 28.1 〃 B: 〃 = 20/80 31.2 〃 C: 〃 = 30/70 26.9 〃 D: 〃 = 60/40 19.6〃 E: MCA-Na / AAM = 20/80 26.9〃 F: AAM = 100 29.6〃 G: AMPS-Na / AAM = 10/90 28.9〃H : 〃 = 20/80 27.8 Polymers A to D are ACA-Na / AAM type, E is sodium methacrylate (hereinafter abbreviated as "MCA-Na") / AAM type, and F is AAM homopolymer. , G, H is 2
-Sodium acrylamido-2-methylpropanesulfonate (hereinafter abbreviated as "AMPS-Na") / AAM system. Examples 1 to 5 and Comparative Examples 1 to 5 An improvement test was performed using a Kanto loam layer having a water content ratio of 115 % (collection place: Minamiotani, Machida City, Tokyo) as a raw material soil.

The raw material soil was subdivided into plastic bags of 7 kg each and subjected to an improvement treatment. The improvement treatment was carried out by sprinkling 7 g of each water-soluble polymer powder in a plastic bag and mixing them, and then 210 g of quicklime powder was added and stirred.
Further, it was immediately sealed so that the water content would not fly off. After 6 days of sealed curing, according to JIS A1210 (method for compaction of soil by compaction), divide the improved soil into 3 layers in a mold with an inner diameter of 15 cm and compact it 92 times with a 4.5 kg rammer.
A tamping test was performed.

Next, according to JIS A1211 (CBR test method), preparation for a water immersion expansion test was carried out and the amount of expansion was traced by immersing in a water tank for 4 days. Further, after taking out from the water tank to remove water and performing a predetermined measurement after 15 minutes, C
BR (CaliforniaBearing Rati)
o) A load-penetration amount curve was obtained using a tester. The load (hereinafter referred to as "penetration strength") at a penetration amount of 2.5 mm is read, and the CBR is calculated by the following formula. As the standard load in the formula, a standard load of 1,370 kg at 2.5 mm penetration defined by JIS was used.

CBR = (penetration strength / standard load) × 100 (%) The larger the CBR value, the higher the strength. Moreover, the state of the improved soil was visually observed. Table 1 summarizes the test results
It was shown to. Further, the expansion ratios obtained from the simultaneously measured expansion amounts after 4 days of immersion in water were all good at 1% or less.

[0024]

[Table 1] *) As it was a soft clay, it did not hang on the tamping tester, so I tamped it by hand for reference.

Examples 6 and 7 and Comparative Examples 6 to 8 Polymer B was used and treated in the same manner as in Example 1 except that the amount of lime was changed, and the test was conducted.

The results are shown in Table 2. Comparative Examples 6 to 8 were all treated with lime alone. The results of the water immersion expansion test were all swelling ratios of 1% or less. In addition, Table 2 also includes Example 2 for comparison.

[0027]

[Table 2]

[0028]

EFFECTS OF THE INVENTION The residual soil having a high water content ratio, which has been conventionally difficult to use and is a subject of illegal dumping, can be improved in a plant without being directly dried in the sun by using the water-containing soil improving agent of the present invention. , It can be reused as a resource for backfilling. In this way, it contributes to the local community by preventing the illegal dumping of residual soil and the environmental destruction caused by the extraction of sand for backfilling.

Claims (5)

(57) [Claims] 1. A water-containing soil improving agent comprising a water-soluble polymer having a carboxyl group and lime. 2. A water-soluble polymer having a monomer composition
Containing 5 to 60 mol% of a monomer having a carboxyl group.
The improvement of the hydrous soil according to claim 1, characterized in that
Agent 3. A water-soluble polymer, (meth) Improvement of water-containing soil according to claim 1 or 2, wherein the acrylic acid or its salt is (meth) acrylamide-based polymer copolymerized structure Agent 4. The weight ratio of water-soluble polymer to lime is 1: 1 to 1.
1: of claims 1 to 3 characterized in that it is a 500
Remediation agent for hydrous soil according to any one of 5. A water-containing soil having a water content ratio of 40 to 200.
And the inclusion according to any one of claims 1 to 4.
Water soil improver