JPH0770563A - Conditioner for water-containing soil - Google Patents

Abstract

PURPOSE:To provide a conditioner which can effectively condition a high-water- content residual soil which is conventionally difficultly utilizable and often unlawfully dumped. CONSTITUTION:The conditioner comprises a first component which is a mixture of a powder of a water-soluble carboxylic polymer with a powder of a substance inert to the polymer in a weight ratio of from 1:0.05 to 1:10 and a second component comprising lime.

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, see the hydrated soil, which is the construction surplus soil (hereinafter referred to as "remaining soil") that accompanies construction and civil engineering.
The present invention relates to an improving agent used when soil is improved and reused as a resource.

[0002]

2. Description of the Related Art Conventionally, most of the remaining soil generated in various places has not been reused and has been disposed of in landfills or transported to other places. Is increasing. 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 the case of road construction, sand is legally required to be used for backfilling the excavated site. 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 of the residual soil treatment using quick lime is operated. This is to dry the residual soil on a vast site in the sun and improve the residual soil with a low water content with quicklime. On the other hand, when considering an ordinary improvement plant, the site cannot be large, so the residual soil with a high water content generated at the site must be improved as it is without drying in the sun. It is highly sticky and adheres to mixers etc., making it difficult to operate and not processing. Further, there is a problem that the CBR strength cannot be expected to be sufficiently improved even if the treatment is performed.

Therefore, the present inventors have proposed, as a solution to the above problems, an agent for improving water-containing soil, which comprises fly ash, lime and / or gypsum, and a water-soluble polymer (Japanese Patent Laid-Open No. Hei 10 (1999) -58242). 5-59363).

[0005]

With the above-mentioned improver, even if it is used for the residual soil having a high water content, it can be improved in the plant without being dried in the sun as it is. Effective use of ash is also possible. However, as a result of the inventors' detailed examination of the improving agent after that, some problems to be solved became clear.

As a general use form of the improving agent, as in the example of JP-A-5-59363, a water-soluble polymer is first added to and mixed with the residual soil, and then the water-soluble polymer is used. A method of adding and mixing about 50 to 200 times as much fly ash and finally adding lime or gypsum is mentioned. In this embodiment, the effect of adding fly ash is difficult to appear unless a fairly large amount of fly ash is added to the residual soil for practical purposes, such as about 10% by weight. Also,
Actually, fly ash is a fine powder and difficult to mix, and there is a problem that it absorbs moisture and adheres to mixing equipment.In a large-scale plant, add and mix a large amount of fly ash to the residual soil with a high water content. Is actually very difficult.

[0007]

The present inventors have arrived at the present invention as a result of earnestly studying to solve the above-mentioned problems and to develop a further excellent method for improving residual soil. That is, the gist of the present invention is (1) a mixture of a powder of a carboxyl group-containing water-soluble polymer and a powder of a substance inactive to the water-soluble polymer, wherein the mixture of the powder of the water-soluble polymer and the inert substance is A first component having a powder mixture weight ratio of 1: 0.05 to 1:10, and (2)
It exists in a water-containing soil improver characterized by comprising a second component consisting of lime.

The present invention will be described in detail below. The hydrous soil to be improved by the present invention is a mud with a slump value of 4 cm or less, particularly 2 cm or less, which has low fluidity and can be carried out by a dump truck or the like. The improvement effect of the present invention can be mainly expected when the water content ratio is usually 40 to 200%, particularly 60 to
It is a soil with a high water content ratio of about 150%, specifically, it is the residual soil that accompanies general civil engineering and construction work such as domestic water and sewer construction, road construction, and residential land development.

Here, the slump value means JIS A11.
It is a scale of fluidity measured by 01 (concrete slump test method). Actually, bottom surface 20φcm, top surface 1
Place the “slump cone” with a diameter of 0φ cm and a height of 30 cm and an empty upper and lower surface on a flat plate, squeeze the soil from the top, and pull the slump cone upward to change the height from the top surface (30 cm). It is expressed in cm. The water content ratio is 1
The ratio of the mass of soil water lost by oven drying at 10 ° C to the oven dry mass of soil, expressed as a percentage.
It is a value measured by S A1203 (water content ratio test method).

The soil material includes loam layer, gravel, earth and 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. Those having a high water content include, for example, the Kanto loam layer, which usually has a water content of about 60 to 120% and has high tackiness, but is solidified and granulated by using the improving agent of the present invention. Therefore, sand-like fluidity is imparted, tackiness and swellability in water are eliminated, ground support capacity is improved, and backfilling can be reused.

Therefore, the improvement of the water-containing soil in the present invention means that the water-containing soil having softness or high stickiness is reused for backfilling, so that the penetration strength is usually increased to 10 kg / cm ² or more, and It is to impart fluidity like sand and to be solidified so as not to swell in water. Therefore, the improvement in the present invention does not mean that the water-containing soil is simply solidified into a solid state to lose fluidity.

The water-soluble polymer which is a constituent of the first component of the water-containing soil conditioner of the present invention is usually at least 100.
It is a polymer that dissolves more than 1 g in ml water. The polymer is
A monomer having a carboxyl group as a hydrophilic group, and a monomer having a carboxyl group in all monomer units constituting the polymer is usually 1 to 80 mol%, preferably 5 to 60
Mol% is included. In addition, the carboxyl group may be present in either free acid or salt form.

Examples of the salt include alkali metal salts such as sodium and potassium, alkaline earth metal salts 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 the water-soluble polymer include (meth) acrylic acid or a salt thereof and a (meth) acrylamide copolymer, maleic acid or a salt thereof and a vinyl acetate copolymer, itaconic acid or a salt thereof and (meth) Synthetic water-soluble polymers such as copolymers with acrylamide, natural water-soluble polymers such as gum arabic, karaya gum, lint gum, alginic acid, and semi-synthetic water-soluble polymers such as carboxymethyl cellulose, carboxyhydroethyl cellulose and guar gum modified products. An example is coalescence.

Of the above carboxyl group-containing water-soluble polymers, a copolymer of (meth) acrylic acid or a salt thereof and (meth) acrylamide is preferable. (Meta)
Examples of the (meth) acrylamide-based polymer containing acrylic acid or a salt thereof include those obtained by copolymerizing (meth) acrylic acid or a salt thereof with (meth) acrylamide,
A partially hydrolyzed homopolymer of (meth) acrylamide may be used.

Further, in the above-mentioned carboxyl group-containing water-soluble polymer, a monomer containing a sulfonic acid group as a hydrophilic group,
For example, vinyl sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof may be included in the copolymer. Further, a hydrophobic monomer such as an olefin, an acrylic ester, or a vinyl ester may be contained so 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. The method for producing the water-soluble polymer is not particularly limited, but is generally a radical polymerization method, and solution polymerization using water or a lower alcohol as a solvent is adopted. The concentration of the monomer is usually 10% by weight or more, preferably 15 to 60% by weight.
When the polymerization initiator is polymerized with an aqueous solvent, potassium persulfate,
Peroxides such as ammonium persulfate, and redox-based initiators, N, N'-azobis- (2-
Amidinopropane) dihydrochloride, 4,4'-azobis-
Water-soluble radical polymerization initiators such as (4-cyanovaleric acid) -2-sodium are preferred. The amount of radical polymerization initiator used is based on the weight of the copolymerizable monomer mixture.
Usually 0.005 to 5% by weight, preferably 0.05 to 0.
It is 5% by weight.

The polymerization method is not particularly limited, but if an aqueous solution polymerization is exemplified, a method of performing polymerization with stirring, a method of performing polymerization in an adiabatic state by allowing it to stand in a container, a method of performing heat removal in a sheet form, and water in oil A method of polymerizing in a type emulsion or dispersion state is exemplified. As a method of standing and polymerizing, after removing oxygen from a predetermined monomer aqueous solution through nitrogen gas, the mixture is brought to a predetermined temperature, and a radical polymerization initiator is added and uniformly mixed. 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 90 ° C.

The water-soluble polymer as described above is usually used after being dried and pulverized into a powder form. The polymer powder preferably has an average particle size of 0.05 to 0.4 mm. Furthermore, considering operability, etc., the particle size is 0.4
Particles larger than mm and particles smaller than 0.05 mm are
It is advisable to use particles having a uniform particle size distribution such that the total particle content is 15% by weight or less, preferably 10% by weight or less. In order to obtain powder within such a range, if necessary, sieving,
Mixing is performed. When the particle size exceeds 0.4 mm, it takes time to develop the improvement effect, while the particle size is less than 0.
If it is less than 05 mm, particles tend to adhere to each other due to moisture absorption to form lumps, and similarly, the improvement effect takes time, which is not preferable.

Another component of the first component of the water-containing soil conditioner of the present invention is a powder of a substance inactive to the above water-soluble polymer. The substance which is inactive to the water-soluble polymer is a fine powder mainly composed of an inorganic material which does not react with the carboxyl group of the water-soluble polymer, and is mainly fly ash, diatomaceous earth, acid clay, alumina, bentonite, kaolin, silica, Examples are talc and kaolinite. Of these, fly ash is particularly preferable. Fly ash is generally ash extracted from smoke-bearing gas of a pulverized coal combustion boiler, but normally coal ash generated in a coal-fired power plant is used. The composition of fly ash varies slightly depending on the raw coal, but as a constituent, SiO ₂ is usually 50 to 50%.
70 wt%, Al ₂ O ₃ is 10 to 40 wt%, other Fe
₂ O ₃ , CaO, MgO, etc. are contained. Further, the particle size of the powder of the substance which is inactive to the water-soluble polymer is not particularly limited, but the average particle size is usually smaller than that of the water-soluble polymer and is about several hundred μm or less.

The first component of the water-containing soil conditioner of the present invention is
A mixture of the above-mentioned carboxyl group-containing water-soluble polymer powder and powder of an inactive substance for the water-soluble polymer, wherein the mixture weight ratio of the water-soluble polymer and the inactive substance is 1:
0.05 to 1:10, preferably 1: 0.25 to 1: 4
Is. If the mixing weight ratio is out of the above range, the effect of improving the residual soil per unit water-soluble polymer decreases, which is not preferable. The powder of the substance which is inactive to the water-soluble polymer prevents the adhesion of the water-soluble polymer particles of the first component due to moisture absorption, improves the dispersibility in soil, and promotes the hardening reaction of soil with lime as the second component. It is presumed that it contributes to

In the hydrated soil improving agent of the present invention, the above-mentioned first component is usually added to and mixed with the residual soil, and then lime as the second component of the hydrated soil improving agent is added and mixed with the residual soil.
The use ratio of the first component and the second component is not particularly limited, and lime may be used in a large excess, but usually 1: 0.1 to 1: 1.
00, preferably about 1: 1 to 1:50.

The lime may be quick lime or slaked lime, preferably quick lime. As quicklime,
Usually, a commercially available product may be used, but the product obtained by burning and crushing the bone shells of fish and shellfish generated from the general food industry and household, and the shells attached to the cooling pipes of power plants, etc. It is also possible to use lime, and the lime as described above is usually powder having an average particle size of 1 mm or less.

The amount of the improving agent of the present invention to be used in the water-containing soil as described above is the water-containing soil to be improved (remaining soil).
Although it is not particularly limited, it is usually 0.2 to 20% by weight, preferably 0.5 to the residual soil.
10 to 10% by weight.

Further, if necessary, when the improving agent of the present invention is used as a treated hydrous soil in which fine aggregate is added and mixed in the residual soil, the strength of soil or the bearing capacity of the soil is synergistic. It is particularly preferable because it is improved. As fine aggregate,
Examples include crushed concrete, sand, gravel, and crushed stone, which have an average particle size of usually about 0.2 to 10 mm. In addition, the effect of improving soil can be adjusted by using gypsum, hydraulic cement, superabsorbent resin, and the like as optional components.

Next, a specific method of using the water-containing soil improving agent of the present invention will be described. Usually, it is preferable to first add and mix the first component of the improving agent of the present invention to the treated soil, then mix the second component of lime and further cure. In addition,
As the water-containing soil to be treated, as described above, one obtained by adding and mixing fine aggregate may be used. As an actual treatment operation, the first component is added to and mixed with the water-containing soil.

Specifically, for example, there is a method in which the first component is sprayed on the water-containing soil on a belt conveyor and mixed with a paddle mixer or the like. Alternatively, the water-containing soil and the first component may be directly added to a paddle mixer or the like and mixed. The mixing is preferably carried out for 0.2 to 10 minutes, preferably 0.5 to 5 minutes in consideration of the processing efficiency of the plant, preferably with gentle stirring. In the above cases, the soil will be substantially granulated, but if the stirring is too strong, the soil particles will gradually become finer, and as the mixing time becomes longer, the soil particles will gradually become finer and the strength of the improved soil will be improved. Gradually decreases. After mixing for a certain period of time, stirring may be stopped and an aging time of usually about 1 to 10 minutes may be set.

Next, a mixer is usually used also in the step of mixing the second component, lime, but it is preferable to use an impact mixer, for example, since it is possible to re-separate the associated particles simultaneously with the mixing. If necessary, sieving may be performed. Finally, curing is carried out so that the strength of the particles is expressed, but at room temperature, it is usually 1 day or longer, preferably 3 days or longer. It is preferable to have a roof as a curing method in consideration of rainy weather, but there is no problem even if it is piled open.

[0028]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. (Polymer used) Table 1 shows the polymer used in the experiment.
~ Is a self-made product, and ~ is a commercial product. Measure the amount of anion by colloid titration method, 25 ℃, 0.1g
The reduced viscosity was measured as a 1N saline solution of / dl. The average particle size was adjusted by sieving.

[0029]

[Table 1]

(Preparation of the first component of the improving agent) The powder of the polymer shown in Table-1 and the powder of the substance inactive to the polymer were sufficiently mixed at the ratio shown in Table-2 to prepare the first component of the improving agent. One component was prepared. As fly ash, Mitsubishi Kasei Co., Ltd.
It was obtained from a coal-fired power plant at the Yokkaichi Plant, and its composition was 59% SiO _{2 and} 30% Al ₂ O _3.
%, Fe ₂ O ₃ was 5%.

[0031]

[Table 2]

Example 1 30 weight of fine aggregate (sand for general mortar, average particle size 0.4 mm) was added to a Kanto loam layer having a water content ratio of 130% and a slump value of 0.0 cm collected in Machida, Tokyo. % And the water content ratio was 72%, which was used as the sample soil. Sample soil 6kg capacity 2
Adopted in 0L Hobart type, stirring 60g of Table-2
When the first component A was added and mixed at 37 rpm for 1 minute, the average particle diameter was 2-3 mm. Then 1
80 g of quicklime was added and mixed at 37 rpm for 0.5 minutes. The stirring was stopped, and the improved soil was immediately taken out, placed in a polyethylene bag and sealed.

After performing a hermetic curing at room temperature for 6 days, JI
According to S A1210 (method for compaction test of soil by tamping), mold-modified soil having an inner diameter of 15 cm was divided into 3 layers, and each was tamped 92 times with a 4.5 kg rammer to perform a compaction test. Next, JIS A1211 (CB
R test method), and prepare for the flood expansion test 4
The amount of expansion was traced by immersing in a water tank for a day. Further, after taking out from the water tank to remove water and performing a predetermined measurement after 15 minutes, CBR (California Bearing)
A load-penetration amount curve was determined by a Ratio tester.
Load at a penetration of 2.5 mm (hereinafter abbreviated as penetration strength)
Was read and CBR was calculated by the following formula. The standard load in the formula was 1,370 kg, which is the standard load for 2.5 mm penetration defined by JIS.

[0034]

[Equation 1] The larger the CBR value, the higher the strength. Moreover, the state of the improved soil was visually observed. The test results are shown in Table-3.
In addition, in Table 3, the addition amount of each component of the improving agent is shown by weight% with respect to the sample soil.

Examples 2 to 5 and Comparative Examples 1 to 7 Table 3 shows the results of the same tests as in Example 1 except that the amount of the improver used was changed as shown in Table 3. Comparative Example 1 shows the physical properties of the sample soil as it is. Comparative Examples 2 and 3
Is a mixture in which only the second component, quicklime, is added to and mixed with the sample soil. In Comparative Example 4, only the first component was added and mixed. In Comparative Examples 1 and 4, the adhesiveness was so great that the tamping tester did not apply the tampering test, so the tampering was done by hand.

In Comparative Example 5, only the polymer was first added and mixed, and then quicklime was added and mixed. In Comparative Example 6, only fly ash was first added and mixed, and then quicklime was added and mixed. Furthermore,
In Comparative Example 7, the polymer was first added and mixed, then fly ash was added and mixed, and quick lime was finally added and mixed. In Comparative Example 7, a large amount of fly ash was used, but there was almost no difference in the improvement effect of the treated soil from Comparative Example 5 in which no fly ash was used, and the improvement effect was inferior to the results of the Examples. You can see that

[0037]

[Table 3]

Examples 6 to 15 and Comparative Examples 8 to 13 Tests were carried out in the same manner as in the above examples, using Kanto loam layers having a water content of 106% and a slump value of 0.0 cm collected in Hachioji, Tokyo. The results are shown in Table-3.

[0039]

[Table 4]

[0040]

EFFECTS OF THE INVENTION By using the water-containing soil improving agent of the present invention, it is possible to efficiently improve the soil quality of the residual soil having a high water content ratio, which has hitherto been difficult to use and has been illegally dumped.
The improved residual soil can be reused as a resource for backfilling as it is. In this way, it is possible to prevent illegal dumping of residual soil and environmental destruction due to sampling of backfilling sand, and also to reduce environmental pollution due to sampling of backfilling sand.

Claims (3)

[Claims] 1. A mixture of a powder of a water-soluble polymer containing a carboxyl group and a powder of a substance inactive to the water-soluble polymer, which is a mixture of the powder of the water-soluble polymer and the powder of an inactive substance. A first component having a weight ratio of 1: 0.05 to 1:10,
(2) A hydrated soil improver, which comprises a second component made of lime. 2. The use ratio of the first component and the second component is 1:
The water-containing soil improver according to claim 1, which is 0.1 to 1: 100. 3. The fly ash as the substance inactive to the carboxyl group-containing water-soluble polymer.
Of water-containing soil.