JP2005336232A - Soil solidification agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a soil solidification agent which is effective for the solidification of organic/inorganic soft soils produced by dredging or at construction sites, confines heavy metals or malodors in the solidified soil, does not re-elute them, prevents secondary environmental contamination, is applicable for a spray seeding work which is water resistant and not washed away by rain and improves soils for reutilization. <P>SOLUTION: This soil solidification agent comprises 60-90 wt.% of [agent A] a base component of the solidification agent which is a homogeneous mixture of 60-90 wt.% of paper making sludge ash or flyash and 10-30 wt.% of blast furnace cement or Portland cement and 10-40 wt.% of [agent B] as a reactive agent of the solidification agent which is a mixture of 10-20 wt.% of aluminum sulfate, 20-30 wt.% of blast furnace slag, 40-60 wt.% of calcium sulfate, 10-20 wt.% of silicon dioxide (silica), 10-20 wt.% of sodium carbonate and 10-20 wt.% of sodium sulfate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is effective for solidifying organic / inorganic soft soil generated from dredging / construction sites, containing heavy metals and odors in solid products, preventing secondary environmental pollution without re-elution, It is related with the soil solidification processing agent which improves and enables reuse.

  Conventionally, cement-based solidifying agents, lime-based solidifying agents and the like are often used for solidifying soft soil generated from dredged soil from rivers and lakes or construction sites. Lime-based solidifying agents are limited to sludge and organic soils. However, when these solidifying agents are used, the pH becomes strongly alkaline and adversely affects the ecosystem of the natural environment. Also, cement solidifying agents have a solidification reaction due to the solidification mechanism, and if there is organic matter in the target soil. It may be hindered or sometimes not effective at all. On the other hand, the application range of the lime-based solidifying agent is wide, but the problem that the alkaline component leaches out from the solidified soil for a long time remains. Cement-based solidifying agents have a drawback that the curing period required for solidification is about 4 to 7 days, and they cannot be carried out or worked immediately after mixing with soft soil. The Japanese curing reaction is inhibited, and the function as a solidifying agent may be lost. There is also a problem that hexavalent chromium may be eluted. On the other hand, the lime-based solidifying agent has problems such as high heat, water vapor and bad odor, etc., and there is a problem that alkali is eluted from the treated product after solidification treatment, which is a big problem from the viewpoint of environmental conservation. Have Further, these solidifying agents cannot adjust the solidification strength and cannot be dug up, so that they cannot be reused, and when they are dug up, there is a problem that industrial waste must be treated. Since conventional solidifying agents cannot fix heavy metals dissolved in soft soil or the like, odor sources, etc., it can be said that these harmful substances are likely to be eluted from the treated product after the solidification treatment.

In addition, Patent Document 1 is seen as being similar to the one intended by the present invention. Paper sludge ash is used as a raw material, 50 to 70% by weight, blast furnace slag 10% by weight, lime or quick lime 10 to 20% by weight, A soil solidifying agent mixed with 10 to 20% by weight of calcium sulfate is used, but it takes 2 hours to be able to work with heavy machinery, and continuous work is not possible. Not suitable for.
JP2002-88362

  The present invention is effective for solidifying organic / inorganic soft soil generated from dredging / construction sites, etc., containing heavy metals and odors in the solidified product, preventing re-elution, preventing secondary environmental pollution, It is intended to provide a soil solidification treatment agent that is resistant to water and that can be applied for greening spraying that does not flow out into the rain, etc., and that can improve soil and reuse it.

  Here, the present inventor, as a soil solidifying agent, solidified main agent [agent A] 60-90 wt% in which paper sludge ash or fly ash 60-90 wt% and blast furnace cement or Portland cement 10-30 wt% were uniformly mixed. %, Aluminum sulfate 10-20 wt%, blast furnace slag 20-30 wt%, calcium sulfate 40-60 wt%, silicon dioxide 10-20 wt%, sodium carbonate 10-20 wt%, sodium sulfate 10-20 wt% As a result, a solidifying agent reactant [B agent] mixed with 10 to 40% by weight was found.

The soil solidification treatment agent of the present invention does not solidify itself, absorbs bad odors, has good water permeability, is easy to dig up, has very good vegetation, and does not run away even in strong rain, Even after improvement, it can be reused as good soil.
Since the main raw material of the present invention is paper sludge ash and fly ash, the amount of industrial waste can be reduced by reusing what was conventionally treated as industrial industrial waste at paper mills and power companies. In other words, it contributes to extending the life of the final disposal site.

  The soil solidifying agent of the present invention does not elute alkali, does not affect vegetation, and does not affect the surrounding environment. In addition, the input amount is as small as 3 to 7% as compared with cement-based and lime-based materials, and it becomes possible to work with heavy machinery immediately after the completion of stirring. In addition, the soil stabilizer of the present invention fixes a large amount of water as crystal water inside the porous structure, and at the same time, promotes absorption and solidification of harmful components, further encloses harmful heavy metals and exerts a deodorizing effect.

  The soil solidification treatment agent of the present invention is mainly composed of the incinerated ash, and contains aluminum sulfate, calcium sulfate, sodium sulfate, silicon dioxide, sodium carbonate, and blast furnace slag, and is hydrated with coexisting water. The reaction proceeds with certainty, producing ettringite and exhibiting excellent water absorption. As a result, a large amount of water is consumed by the hydration reaction itself, and a large amount of organic matter, harmful heavy metals, etc. are taken into the hydrate produced by the reaction.

  Furthermore, in the present invention, by absorbing water into a porous structure, the odor in the sludge caused by the components dissolved in the sludge moisture is reduced in a short time by water absorption solidification, and there is almost no odor at the end of solidification. There is a nature to change. In addition, the physical water absorption action has an action of taking in harmful substances such as heavy metals existing in an ionic state, and further has an action to prevent re-elution of the taken-in substances.

  For this reason, the soil solidification treatment agent of the present invention is effective in a site where rapid solidification is required or a site containing a large amount of organic matter. In addition, if there are harmful substances or odorous substances in the target soil, it is applicable to containment and treatment of these substances. Furthermore, by adjusting the compaction, the hydraulic conductivity is maintained, and it is effective for the greening of the application area after improvement.

  The soil solidification treatment agent of the present invention can exhibit a stable function in various soils containing inorganic and organic materials, for example, high moisture content sludge, inorganic and organic silt, and improved treatment of corrosive soils. Contain toxic substances and prevent re-elution. Moreover, since the pH of the soil after the stabilization treatment is maintained in a neutral range by the buffering action of the solidification aid, it is extremely advantageous for environmental protection. Moreover, since the water permeability of the treated soil is maintained, it is optimal for a place where greening after soil improvement is required. In addition, various properties such as water permeability, containment of the treated soil, fusion with general soil, and excavation are possible, and sludge can be reused.

  Thus, since the application range is wide, there is no significant change in the amount of addition due to changes in the soil to be treated, which is extremely advantageous for process management. The specific gravity is small and it can be said that there is an advantage in terms of the transportation cost of the soil after the treatment as compared with the cement-based solidifying agent.

  The soil solidification treatment agent of the present invention is a gray powder having a relatively small specific gravity, which is produced by blending a papermaking sludge ash or fly ash as a main component with an alkali preparation agent, a buffering agent, and a solidifying agent. It can be said that one of the features of the soil solidifying agent of the present invention is the physical structure of papermaking sludge ash and fly ash which are the main components. Since paper sludge ash and fly ash are fine inorganic products produced by high-temperature combustion, the porosity of the particles is high, and this shows adsorption performance for organic and inorganic substances similar to the action of activated carbon. Therefore, it absorbs odors and malodorous components (hydrogen sulfide, volatile organic acids, lower amines, ammonia, etc. that are decomposed and generated under anaerobic conditions of organic matter) present in the sludge, stronger water absorption and subsequent physicochemical reaction Re-elution of adsorbate is prevented by the action of hydrate produced in This action is not limited to organic substances, but it is contained in a clathrate by physicochemical reactions that appear in the process of solidification proceeding simultaneously with dissolved harmful substances of inorganic heavy metals. In the case of the lime-based solidifying agent, it was said that alkali elution continued and adversely affected vegetation. Can be kept good.

  The characteristics of curing are described below. [Initial curing] The soil solidifying agent of the present invention is different from a cement-based solidifying agent that takes in water as part of a chemical reaction. Water absorption and subsequent chemical reactions are involved in increasing the initial strength early. With regard to [Medium-term curing], the coagulation effect of the coagulation aid that dislikes the dissolution of organic substances is increased by the organic substance adsorption effect of papermaking sludge ash and fly ash, and the medium-term strength is increased. With regard to [long-term altitude], by incorporating colloidal particles in the soil into the long-term solidification reaction process, the increase in strength and the familiarity with the surrounding soil are realized in a balanced manner over time.

  Hereinafter, the construction method of the soil solidification treatment agent of the present invention will be described more specifically. The machines used include backhoes, stabilizers, and tillers. The backhoe will be described as an example. Multiply the specific volume (usually 1.6) by the volume of the soil to be treated and use it at 3-7% depending on the quality of the soil. In the [spreading], the soil solidifying agent of the present invention is placed on the ground and the backhoe is turned sideways, and the bottom of the flexible container bag is cut and scattered without crossing, but there is also a method using a cement spreader or the like.

When using a backhoe, it is important to use the back side of the bucket and stir frequently so that no large particles are lost and do not form dumplings. The trick is to stir so that the soil color is uniform. There is also a method of using a stirrer for stirring.

In the [rolling pressure], although it varies depending on the required compaction, it is desired to roll the rolling force about every 30 cm. Rolling is performed by agitation on the back of the backhoe bucket after stirring. Then step on the backhoe and use a vibrating roller for finishing. When the soil surface needs to be flattened, it may be leveled using a grader or bulltozer.

Using the following soil solidification treatment agent of the present invention, the target strength of the soil to be solidified is set to 5 kgf / cm ² from the corn index at which the 15-ton bulldozer can work, and the uniaxial compression strength is determined. Since the strength is 1.0 kgf / cm ² , the target addition amount is 2.1%. Table 1 shows the test results of the uniaxial compression test as the basis.

  The contents of the soil solidifying agent used above are as follows. 60-90% by weight of paper sludge ash, 10-30% by weight of blast furnace cement, 60-90% by weight of solidifying agent (A), 10-20% by weight of aluminum sulfate, 20-30% by weight of blast furnace slag , Calcium sulfate 40-60 wt%, silicon dioxide 10-20 wt%, sodium carbonate 10-20 wt%, sodium sulfate 10-20 wt% mixed solidifying agent reactant [B agent] 10-40 wt% Become.

The soil solidification treatment agent of the present invention can be used in the following fields.
(B) Fields of soil treatment generated during the development of water resources regardless of public or private sector (b) Fields of soil and sludge treatment related to agriculture, farmland, and livestock industry (c) Water treatment, sewage, and industrial water treatment Fields of sludge treatment generated in related fields (d) Fields of application such as slope construction and restoration (e) Fields utilizing the water permeability function of soil treated with the soil solidifying agent of the present invention (f) Greening project, ground, Sports facilities maintenance business field (G) Fields that take care of natural roads such as promenades, parks, riverbeds, etc.

Claims (1)

60-90% by weight of solidifying agent [agent A] in which paper sludge ash or fly ash 60-90% by weight, 10-30% by weight of blast furnace cement or Portland cement are uniformly mixed, 10-20% by weight of aluminum sulfate, blast furnace Solidifying agent reactant [B agent] mixed with 20-30 wt% slag, 40-60 wt% calcium sulfate, 10-20 wt% silicon dioxide, 10-20 wt% sodium carbonate, 10-20 wt% sodium sulfate 10 A soil solidification treatment agent consisting of -40% by weight.