JPH11278911A - Solidifying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solidifying material capable of providing a high strength and effectively utilizing wastes. SOLUTION: This solidifying material is obtained by mixing 100 pts.wt. of a baked material made from one or more kinds selected from a municipal refuse incinerated ash and a sewage sludge incinerated ash as a raw material and containing 10-40 wt.% of one or more kinds of C11 A7 CaCl2 , C11 A7 CaF2 and C3 A and further containing C2 S and/or C3 S with 5-50 pts.wt. of a gypsum and 10-60 pts.wt. of quicklime and/or slaked lime.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fired material (hereinafter referred to as "eco-cement clinker") produced from waste such as incinerated ash of municipal waste and incinerated ash of sewage sludge, and a solidified material using gypsum and lime. In particular, the present invention relates to a solidified material suitable for improvement of residual soil and solidification of volcanic ash clayey soil.

[0002]

2. Description of the Related Art A large amount of residual soil is generated in large-scale earthworks such as underpasses, subways, and common ditches, underground excavation work for buildings, and laying work for electricity, telephone, gas, water and sewage. Of these, the cohesive soil is poorly handled due to its properties and is treated with a solidifying material or the like. Also, from the viewpoint of effective use of construction-generated soil, the cases of improving the remaining soil with a solidifying material or the like and effectively utilizing it for various applications are increasing for other sandy soils including cohesive soil.

[0003] In Japan, there are many volcanoes, and soils of volcanic ash origin are distributed in various places. In Japan, where the land is narrow, roads, factories, residential lands and the like are being developed regardless of the nature of the ground. Volcanic ashy clay soil forms a solid soil layer in its natural state, but once it is disturbed by earth-moving machinery etc., it becomes soft and not only difficult to construct, but also greatly reduces the bearing capacity of the ground Therefore, improvement with a solidifying material or the like is generally performed.

As these solidifying materials, general cement or cement-based solidifying materials are also used, but quick lime and slaked lime are said to be effective for the treatment of residual soil and improvement of volcanic ash clay.

[0005] However, quicklime reacts with water in the soil to generate violent heat and accompanying water vapor.
The use in urban areas is limited by the fine powder of quicklime and the scattering of dry soil. Furthermore, since quick lime is usually used in a lump, it needs to be mixed with the target soil and digested again, and then mixed again, which takes a lot of work. On the other hand, slaked lime is
Although the strength increases due to the pozzolanic reaction between soil and lime, this reaction occurs over a long period of time, which is inconvenient for achieving a predetermined strength in a short period of time. Further, when high strength is required, a large amount of slaked lime is required as compared with quick lime, which is uneconomical. In order to solve these problems, there has been disclosed a solidified material that uses powdered lime, reduces the lime content, and mixes Portland cement and gypsum (for example, Japanese Patent No. 8-2503771). Further, other solidifying materials mainly containing cement, lime, and gypsum have been proposed (for example, Japanese Patent Publication No. 63-45276,
JP-B-58-57379, etc.). However, limestone and clay, which are the raw materials of cement used for these, are limited resources.

On the other hand, in recent years, general waste and industrial waste such as municipal waste and sewage sludge have increased remarkably, and effective use and recycling of waste have been attempted in various fields. There is no traditional method, and at present, it depends on landfill. However, recently, in the field of cement production, in order to effectively use and recycle waste, fired products made from waste such as incinerated ash from municipal waste and incinerated ash from sewage sludge (hereinafter referred to as “Eco-cement clinker”) ) Is manufactured.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an eco-cement which has satisfactory performance as a solidifying material, and in which a limited amount of resources is cherished so that waste can be effectively used and recycled. An object of the present invention is to provide a solidifying material that can utilize clinker.

[0008]

Means for Solving the Problems In view of such circumstances, the inventors of the present invention have conducted intensive studies, and as a result, a solidified material obtained by mixing a certain amount of gypsum and lime with the above-mentioned eco-cement clinker has an effect of reducing the water content. The present invention was found to be high and effective for organic soils such as volcanic ash clayey soil, and to exhibit high strength at an early stage, and completed the present invention.

That is, the present invention uses one or more of municipal waste incineration ash and sewage sludge incineration ash as raw materials, and comprises one of C ₁₁ A ₇ CaCl ₂ , C ₁₁ A ₇ CaF ₂ and C ₃ A.
10 to 40% by weight of at least one species or two or more species, and C ₂ S
And / or 100 parts by weight of the calcined material containing C ₃ S, 5 to 50 parts by weight of gypsum, and quicklime and / or slaked lime 10
And to 60 parts by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The eco-cement clinker used in the present invention is composed of at least one material selected from municipal garbage incineration ash and sewage sludge incineration ash.
Al ₂ O ₃ .CaCl ₂ (C ₁₁ A ₇ CaCl ₂ ), 11Ca
_{O · 7Al 2 O 3 · CaF} 2 (C 11 A 7 CaF 2), and 3
One or more of CaO.Al ₂ O ₃ (C ₃ A)
Containing 40 wt%, and _{2CaO · SiO 2 (C 2 S} )
And / or 3CaO.SiO ₂ (C ₃ S). In addition, what added gypsum to this is called ecocement.

The raw material of this eco-cement clinker is sewage sludge dry powder obtained by mixing quicklime with shells and sewage sludge, other general wastes and industrial wastes, and limestone, clay, silica stone, aluminum ash, and other ordinary cement raw materials. It may be a raw material whose components are adjusted by mixing with bauxite, iron or the like.

[0012] The solidified material of the present invention is obtained by mixing the above raw materials with 1200
It is manufactured by pulverizing clinker (eco-cement clinker) fired at １1500 ° C. and then mixing gypsum and lime.

C ₁₁ A ₇ CaCl ₂ , C ₁₁ A ₇
The aluminum sources of CaF ₂ and C ₃ A are mainly derived from incinerated ash, but their content in the fired product is 10%.
When the amount is less than% by weight, the amount of incinerated ash used is small, which is not preferable from the viewpoint of effective utilization and recycling. On the other hand, if it exceeds 40% by weight, excessive swelling may occur due to the progress of hydration, which is not preferable.

It is necessary that the calcined product contains C ₂ S and / or C ₃ S. This is because C ₂ S and / or C ₃
This is because S forms calcium silicate hydrate by hydration and provides stable strength in the long term.

As the gypsum used in the present invention, any of anhydrous gypsum, gypsum dihydrate and hemihydrate gypsum can be used, but anhydrous gypsum having a low dissolution rate is preferred from the viewpoint of the development of strength and the stability of the improved body. Gypsum is preferably added in an amount of 5 to 50 parts by weight based on 100 parts by weight of Ecocement Clinker. If the amount is less than 5 parts by weight, the strength expression is poor. If the amount exceeds 50 parts by weight, not only the strength expression is reduced, but also the stability of the improved product may be reduced due to expansion. A particularly preferred range is 10 to 40 parts by weight based on 100 parts by weight of Ecocement Clinker.

The quick lime and / or slaked lime used in the present invention is 10 parts by weight per 100 parts by weight of Ecocement Clinker.
It is preferable to add 〜60 parts by weight. If the amount is less than 10 parts by weight, the effect of reducing the water content is small and the strength developability is also reduced. On the other hand, if the amount exceeds 60 parts by weight, not only problems such as the case where lime is used alone occur, but also if it is used for improving the remaining soil, the strength development of soil other than the clayey soil is reduced. A particularly preferred range is 20 to 50 parts by weight based on 100 parts by weight of Ecocement Clinker.

Quick lime reacts with water in the soil to become slaked lime and absorbs water, and at the same time, evaporates the water due to heat generated by the digestion reaction, thereby reducing the water content. In addition, the volume expansion due to digestion exerts a consolidation effect on the surrounding soil.
Further, in quicklime and slaked lime, calcium ions generated by dissolution in water are adsorbed on the surface of soil particles to promote aggregation, and in the long term, contribute to increase in strength by a pozzolan reaction between the soil particles and lime. Therefore, although quick lime is more effective than slaked lime, slaked lime is suitable when slurry is used by adding water to the solidified material.

[0018]

EFFECT OF THE INVENTION C ₁₁ A ₇ C in Ecocement Clinker
aCl ₂ , C ₁₁ A ₇ CaF ₂ and C ₃ A form ettringite as a hydrate with the added gypsum. Further, C ₂ S,
Ca (O) produced by hydration of C ₃ S and digestion of quicklime
H) also produces ettringite in the form of consuming ₂ ; Since ettringite has about 45% of its own weight as water of crystallization, it has an effect of reducing the apparent water content and exhibiting high strength. In addition, since the ettringite formation reaction proceeds smoothly even in the presence of organic matter, it is very effective for organic soil. Further, C ₁₁ A ₇ CaCl ₂ , C ₁₁ A ₇ CaF ₂ , C ₃ A in ecocement clinker
The reaction that produces ettringite is much faster than other cement minerals, and is effective for early strength development. In addition, long-term strength can be stably secured by the generation of calcium silicate hydrate by hydration of C ₂ S and C ₃ S. Lime also contributes to an increase in strength in the long term. Therefore, the solidified material of the present invention not only can effectively utilize resources but also has excellent performance as a solidified material.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

EXAMPLE 1 A rotary kiln was prepared using 29.7% by weight of dried municipal incineration ash, 68.6% by weight of limestone powder, 1.5% by weight of aluminum ash and 0.2% by weight of clay shown in Table 1. Was used to fire Ecocement Clinker at 1300-1450 ° C. The obtained clinker was pulverized by a vertical mill so that the Blaine specific surface area became 4000 cm ² / g. Table 2 shows the mineral composition.

[0021]

[Table 1]

[0022]

[Table 2]

The pulverized product of the eco-cement clinker (eco-pulverized product), quicklime having a particle size of 3 mm or less, and a specific surface area of 4.00
A solidified material having the composition shown in Table 3 was trial-produced using anhydrous gypsum of 00 cm ² / g.

Using the sandy soil and the Kanto loam having the properties shown in Table 4, the respective solidifying materials shown in Table 3 were added to the sandy soil by 4% and the Kanto loam by 12% (all in terms of percentage by weight based on the wet sample). Mixed. The kneaded material is 5φ × 10cm and CBR
After being molded into a mold, it was cured at 20 ° C. to a predetermined material age, and the uniaxial compressive strength and the amount of water immersion expansion were determined. The kneading was performed with a Hobart mixer for 5 minutes. The uniaxial compressive strength was determined according to the Japan Geotechnical Society standard (JGST 511), and the amount of water immersion and expansion was determined according to the Japanese Geotechnical Society standard (JGS T 721). Table 3 shows the results.

[0025]

[Table 3]

[0026]

[Table 4]

From the above results, it can be seen that if the amount of gypsum is small, the expansion amount is small, but the strength development is poor, and in the case of sandy soil, the fluctuation width of the strength according to the amount is larger than that of loam. On the other hand, when the amount of the gypsum is large, the strength is reduced, and in addition, the expansion amount is increased. In addition,
Sandy soils with a low water content show greater expansion. On the other hand, if the amount of quick lime is small, the strength development is low, and particularly, the loam is more affected by the effect. When the amount of quick lime is large, the strength tends to be high in the loam, but greatly decreases in the sandy soil. In addition, the amount of swelling is increased by increasing the amount of quicklime, but it can be seen that the degree is smaller than when gypsum is increased.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // (C04B 28/14 B09B 3/00 304G 7:28 22:06) (C04B 28/02 7:28 22:14 22:06) C09K 103: 00

Claims (1)

[Claims] 1. A method comprising using one or more selected from municipal refuse incineration ash and sewage sludge incineration ash as a raw material, and comprising C ₁₁ A ₇ CaC
one or more of l ₂ , C ₁₁ A ₇ CaF ₂ and C ₃ A
Contains 0 to 40 wt%, and with respect to the calcined product 100 parts by weight containing C ₂ S and / or C ₃ S, was mixed with the gypsum 5-50 parts by weight quicklime and / or slaked lime 10 to 60 parts by weight A solidified material characterized by the following.