JP2002363560A - Soil-aggregative caking agent for improvement of highly hydrous soft soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil-improving agent being capable of raising strength more than the previous one to improve highly hydrous soft soil and sludgy slime in a soil-aggregative soil environment preferable for vegetation of plants as well as to suppress extremely the using amount of cement compounded to enhance soil strength while extremely suppressing harmful for a biological system of plants recycling incinerated ash such as fly ash and paper sludge ash being generated as a large quantity of wastes. SOLUTION: A soil-aggregative caking agent for improvement of highly hydrous soft soil comprises mixing 7-30 pts.wt. of Portland cement, 3-15 pts.wt. of a sulfuric acid band, 0.7-10 pts.wt. of anhydrous qypsum, 0.3-5 pts.wt. of methacrylate, 0.08-0.53 pts.wt. of lignin sulfonates, 0.07-0.40 pts.wt. of stearates, 0.04-0.27 pts.wt. of sodium tripolyphosphoric acid and 0.01-0.068 pts.wt. of sodium hydroxide, to 100 pts.wt. of powdered incinerated ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a soil for providing soft soil or sludge-like sludge having a high water content to general agricultural soil or more, and for forming aggregated soil suitable for plant growth. It relates to an improver.

[0002]

2. Description of the Related Art Soft soil and sludge-like sludge containing a large amount of water are not suitable for use in residential lands, parks, promenades, etc. because they are washed away by rainwater as they are, and it is not easy to enter. Also, the cultivation of agricultural products cannot be used as farmland because the conditions for growing plants are not established. In order to use such a highly hydrous soil, it is necessary to improve the soil and ground suitable for the purpose of use. Therefore, for the purpose of such soil improvement, soil improvement work using a cement-based or lime-based solidifying agent has been generally performed.

[0003] When a cement-based solidifying agent is used, the soil can be effectively solidified by a hydration reaction on a highly hydrated soft soil such as sandy soil and the like, thereby strengthening the ground. With respect to sludge soil, the hydration reaction of cement is inhibited by the organic matter contained in a large amount thereof, so that the solidification function is significantly reduced and it is difficult to obtain a sufficient soil improvement effect.

[0004] Further, when a lime-based solidifying agent is used, unlike the above cement, there is an advantage in that the solidifying function is exhibited even in a soil with high water content such as sludge containing a large amount of organic matter, but there is an advantage in that the alkaline There is a danger that strong lime elutes into the surrounding soil and harms crops, and that harmful heavy metal ions contained in sludge re-elute into the surrounding land.

On the other hand, a large amount of fly ash generated after burning the coal or the like is discharged from coal-fired power generation facilities and the like, and paper sludge ash is discharged from a paper mill after incineration to dispose of pulp sludge. Exhausted in large quantities. When the incinerated ash is mixed with high water content soil, it reacts with the water contained in the soil to produce ettrine guide and calcium silicate hydrate, which consumes a large amount of water. It is known that even if the soil contains a large amount of organic matter, it solidifies the soil into aggregates even if the soil contains a large amount of organic matter. Construction work is being carried out to improve the permeable agglomerated soil.

However, when only fly ash or paper sludge ash is mixed, the generated aggregates do not bond with each other, so that the compressive strength of the soil is extremely low and the soil easily collapses. For this reason, even if it is a gentle slope, there was a problem that the soil was easily washed away by rainwater or the like.

[0007] In order to solve the problem, a granulating agent and a solidifying agent for soil improvement as disclosed in JP-A-10-165920 have been proposed. This technology mainly relates to a granulating agent and a solidifying agent in which incineration ash and cement are mixed, but if this soil aggregating agent and the solidifying agent are used to improve the soil, the cement content will be reduced By using 30 to 100 parts by weight with respect to 100 parts by weight of the agent and the solidifying agent, there is a feature that the soil compressive strength can be increased as compared with the case where only incineration ash is used.

However, harmful substances such as hexavalent chromium are usually contained in cement. Therefore, if the mixing ratio of the cement is increased to increase the soil compressive strength, harmful substances such as hexavalent chromium are consequently reduced. The disadvantages of this increase and the strong alkalinity of the cement increase the factor that hinders the normal growth of plants and agricultural products.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and recycles incinerated ash, such as fly ash and paper sludge ash, generated as a large amount of waste, and has a high water content. Minimize the use of cement to improve soft soil and sludge-like sludge into an aggregated soil environment suitable for plant vegetation and to increase soil strength while minimizing the use of cement harmful to plant organisms. It is an object of the present invention to provide a soil conditioner which can suppress and increase the strength more than ever.

[0010]

In order to solve the above-mentioned problems, the present invention relates to a powdery incinerated ash of 100 parts by weight, 7 to 30 parts by weight of portland cement, and 3 to 1 parts of sulfuric acid band.
5 parts by weight, anhydrous gypsum 0.7 to 10 parts by weight, methacrylic acid ester 0.3 to 5 parts by weight, lignin sulfonates 0.08 to 0.53 parts by weight, stearates 0.07
~ 0.40 parts by weight, sodium tripolyphosphate 0.04 ~
0.27 parts by weight, sodium hydroxide 0.01 to 0.06
It is an aggregated solidifying agent for improving a high hydrous soft soil, which is obtained by mixing 8 parts by weight.

Further, in the above structure, paper sludge ash, fly ash ash or a mixed ash of paper sludge ash and fly ash is used as the incineration ash.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the aggregate solidifying agent for improving a highly hydrated soft soil of the present invention will be described in detail below.

[0013] The present invention uses powdered portland cement, a small amount of a pH adjuster, a coagulant, a water-absorbing agent, etc., using incinerated ash such as dry fly ash or paper sludge ash as a main raw material. It is a powdery aggregate-solidifying agent for soil improvement mixed with an additive.

The composition (parts by weight) is as follows. Incinerated ash 100 Portland cement 7-30 Sulfuric acid band 3-15 Anhydrite gypsum 0.7-10 Methacrylate 0.3-5 Lignin sulfonates 0.08-0.53 Stearate 0.07-0.40 Sodium tripolyphosphate 0.04-0.27 Sodium hydroxide 0.01-0.068

The properties of the raw materials to be mixed and the role in the present invention are as follows.

<Incinerated ash> Incinerated ash such as fly ash or paper sludge ash is used. The composition of paper sludge ash is as follows, for example.

Silicon dioxide (SiO ₂ ) 50% Aluminum oxide (Al ₂ O ₃ ) 24% Calcium oxide (CaO) 15.4% Magnesium oxide (NgO) 1.88% Phosphorus pentoxide (P ₂ O ₃ ) 0. 88% ferric oxide (Fe ₂ O ₂ ) 0.71% sulfur trioxide (SO ₃ ) 0.41% titanium oxide (TiO ₃ ) 0.22% potassium oxide (K ₂ O) 0.21% sodium oxide (Na ₂ O) 0.20% Zinc oxide (ZnO) 0.05% Copper oxide (CuO) 0.05%

The composition of fly ash is as follows, for example.

Silicon dioxide (SiO ₂ ) 48% Aluminum oxide (Al ₂ O ₃ ) 31% Ferric oxide (Fe ₂ O ₃ ) 5.65% Calcium oxide (CaO) 4.96% Magnesium oxide (MgO) 2 .36% Potassium oxide (K ₂ O) 1.22% Sodium oxide (Na ₂ O) 1.68% Unburned matter 1.55%

Thus, fly ash and paper sludge ash have similar compositions. Then, such incinerated ash absorbs water in the soil and causes a hydration reaction by the hydrated mineral, so that an ettrine guide is quickly generated. The production of ettrine guide proceeds while decreasing the water content of the soil. The generated ettrine guide crystals form needle-like crystals, and the needle-like crystals rapidly solidify and agglomerate while surrounding the incineration ash and the soil particles. In addition, since the incineration ash itself is porous, organic, heavy metal,
It has the property of adsorbing and absorbing odors in a short time.

<Portland cement> has hydraulic properties,
It has the property of solidifying with the aggregate contained by absorbing water,
It is generally well known as an excellent solidifying agent. As a disadvantage, it cannot exert its solidifying power on fine particles and organic substances. However, it can also be combined with other agents to improve and enhance this disadvantage and enhance the adhesive effect.

<Sulfate band> The pH is lowered to adsorb and fix dissolved pollutants (including heavy metals) eluted in sludge water.

<Anhydrite> Water absorption and solidification by hydration reaction
It has the effect of increasing the strength of the improved soil and helping the cohesive strength of the sulfate band.

<Methacrylic ester> The combination of a sulfate band and anhydrous gypsum greatly enhances cohesive strength. It also has the effect of preventing cracking of the improved soil.

<Lignin Sulfonates> When the cement particles come into contact with the cement particles, they have an effect of uniformly dispersing the cement particles of the cement aggregated particles due to their wetting, permeating and adsorbing actions. Therefore, the cement particles serve as a water absorbing agent by improving the slidability of the whole cement, and at the same time, each cement particle sufficiently comes into contact with water to promote a hydration reaction. In addition, there is an effect that during the lignining, the hydrophilicity of the organic matter / fine soil particle material is enhanced and included, and the cement material is solidified together with the hydration reaction of the cement particles.

<Stearates> The nonionic stearates, when used alone with anionic ligninsulfonates, have the effect of hydrophilizing a hydrophobic material to provide a strong wetting action and uniform dispersion, and have the effect of dispersing with other admixtures. It has the effect of increasing the viscosity by gelling and consolidating.

<Sodium tripolyphosphate> When sodium polyphosphate is added, a large amount of cations are adsorbed via a negatively charged phosphate group or the like, so that the effect of uniformly dispersing becomes large.

<Sodium hydroxide> It is strongly alkaline and serves to neutralize acidic soil. In addition, it has a significant effect on the setting when hydrating the cement, and has an effect of helping uniform dispersibility in the admixture.

Taking into account the properties of the above-mentioned raw materials, mixing is carried out so as to be suitable for the properties and conditions of the soil to be improved within the above range of the mixing weight ratio. The soil improvement work is also performed with the amount of water used to mix with soft soil or sludge-like sludge having a high water content, which is suitable for the purpose of land use.

[0030]

[Embodiment 1] An embodiment in which the land of sludge-like sludge is improved for agricultural land will be described. The mixing amount of the 1-ton aggregated solidifying agent for improvement of high water content soft soil is as follows.

Paper sludge ash 400 kg Fly ash 380 kg Portland cement 80 kg Sulfuric acid band 70 kg Anhydrite 61 kg Methacrylate 3.2 kg Lignin sulfonate 1.2 kg Stearate 0.67 kg Sodium tripolyphosphate 0.43 kg Sodium hydroxide 0 ．1kg Others 3.4kg

[0032]

Embodiment 2 An embodiment in which silt clay land is improved for use as a park sidewalk will be described. The mixing amount of the 1-ton aggregated solidifying agent for improvement of high water content soft soil is as follows.

Paper sludge ash 680 kg Portland cement 180 kg Sulfuric acid band 70 kg Anhydrite 61 kg Methacrylate 3.2 kg Lignin sulfonate 1.2 kg Stearate 0.67 kg Sodium tripolyphosphate 0.43 kg Sodium hydroxide 0.1 kg Others 3 0.4 kg

In the second embodiment, the portland cement is added and blended so as to obtain a strength to the extent that a rut of a bicycle is hardly generated, that is, a uniaxial compressive strength of about 6 kgf / cm ² . Fig. 1 shows the measured data of the amount and strength when this was mixed with silt clay soil. From this data, soil improvement work was carried out at a mixing ratio of 7% with respect to silt clay soil. For example, a uniaxial compressive strength of about 6 kgf / cm ² can be obtained.

[0035]

[Comparative Test Example 1] The present invention relates to organic sludge (A)
A comparison test was conducted between the case where the mixing was performed using the above method and the case where the conventional product (B) Palcoat (trade name of CS Chemicals) was used. The solidifying agents used in this test are as follows.

<The present invention (A)> Paper sludge ash 700 kg Portland cement 160 kg Sulfuric acid band 70 kg Anhydrite 61 kg Methacrylate 3.2 kg Lignin sulfonate 1.2 kg Stearate 0.67 kg Tripolyphosphoric acid of 1 ton in total amount Soda 0.43kg Sodium hydroxide 0.1kg Others 3.4kg

<Conventional product (B)> Paper sludge ash 700 kg of early toughness Portland cement 200 kg Inorganic additive 100 kg

The data of the organic sludge at the time of construction and after 7 days of curing taken for comparison are as follows.

At the time of construction After curing for 7 days Water content (%) 185.6 (Indoor) 180.0 (Site) 134.1 Uniaxial compressive strength (kgf / cm ² ) 0.031 0.031 Cone index (kgf / cm) ² ) 1.53 2.01

The amount of the organic sludge added after curing for 7 days was 3
%, 5%, and 7% are as follows.

<In the case of 3%> The present invention (A) Conventional product (B) Moisture content (%) (indoor) 133.17 146.9 (site) 99.28 118.2 Uniaxial compressive strength (kgf / cm ²⁾ ) 0.117 0.087 Cone index (kgf / cm ² ) 4.26 3.68

<In the case of 5%> The present invention (A) Conventional product (B) Moisture content (%) (room) 125.82 146.3 (site) 86.51 105.5 Uniaxial compressive strength (kgf / cm ²⁾ ) 0.279 0.194 Cone index (kgf / cm ² ) 5.63 4.56

<In the case of 7%> The present invention (A) Conventional product (B) Moisture content (%) (room) 107.1 116.5 (site) 73.66 88.75 Uniaxial compressive strength (kgf / cm ²⁾ ) 0.597 0.391 Cone index (kgf / cm ² ) 7.78 6.98

In the above test results, when the amount of addition to the highly hydrous clay was set to 3%, 5%, and 7%, the results after curing for 7 days were compared. The uniaxial compressive strength of the present invention (A) is about 1.7 times higher than that of the conventional product (B).

At the same time, a decrease in the water content was observed, which is considered to be the result of a significant improvement in water absorption by chemicals such as methacrylate, ligninsulfonate, stearate, and sodium tripolyphosphate. .

[0046]

The present invention is as described above. The incinerated ash such as fly ash ash or paper sludge ash as a main raw material is an excellent soil-aggregating agent for soft soil or sludge-like sludge having a high water content by itself. It is. However, there is a weak point that the strength cannot be improved because the strength is very small as it is.

In the present invention, by mixing portland cement, sulfate band, anhydrite, methacrylic acid ester, ligninsulfonate, stearate, sodium tripolyphosphate and sodium hydroxide into such a main material, Improve soft soil and sludge-like sludge with high water content to a more aggregated soil environment suitable for plant vegetation, and reduce the amount of cement harmful to plant organisms by 30%
It is possible to obtain about 1.7 times more uniaxial compressive strength than before, while suppressing the amount of cement used in this manner as much as possible. While minimizing the content of harmful substances such as harmful substances, it has become possible to avoid alkaline damage to plants and agricultural products.

In the ordinary construction, even if the soil conditioner is mechanically stirred and mixed with the highly hydrated soft soil, uneven stirring tends to occur. However, the use of the aggregated solidifying agent of the present invention realizes the hydrophilization and uniform dispersion of the soil particles by the action of the additive, so that uneven mixing during construction can be eliminated and the efficiency of the mixing operation by stirring can be improved. It has become possible to contribute to improvement and quality improvement of improved soil. In addition, the ability to reuse and consume a large amount of incinerated ash, such as fly ash and paper sludge ash, which are difficult to dispose of, is of great social benefit.

[Brief description of the drawings]

FIG. 1 is a graph showing experimental results using the present invention.

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Claims (2)

[Claims] 1. 100 to 100 parts by weight of powdered incineration ash, 7 to 30 parts by weight of portland cement, 3 to 1 parts of sulfuric acid band
5 parts by weight, anhydrous gypsum 0.7 to 10 parts by weight, methacrylic acid ester 0.3 to 5 parts by weight, lignin sulfonates 0.08 to 0.53 parts by weight, stearates 0.07
~ 0.40 parts by weight, sodium tripolyphosphate 0.04 ~
0.27 parts by weight, sodium hydroxide 0.01 to 0.06
An aggregated solidifying agent for improving a highly hydrated soft soil, comprising 8 parts by weight. 2. The granulated solidifying agent for improving a high hydrous soft soil according to claim 1, wherein the incinerated ash is paper sludge ash and / or fly ash ash.