JP3208537B2 - Grain preparation and stabilization method using solidified cement made from sewage sludge incineration ash - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to sludge incineration ash by-produced in the terminal treatment step of municipal sewage, which has a carbon content of a certain amount or less, and mixes and solidifies the sludge incineration ash with cement. It is related to cement solidified material, and it is used as it is as construction material or as granular aggregate for stable treatment by having a certain level of strength, and it is an environmental business called sewage treatment On waste recycling methods.

[0002] In recent years, the amount of sludge generated due to the spread of sewerage has also increased drastically, and technological development using a melting system has been promoted from the viewpoint of using this sludge as a construction material in order to treat it in large quantities. . That is, 1300 ° C.-14
It melts the inorganic substances in the sludge at a high temperature of 00 ° C. to produce a molten slag which can be easily used as construction material.

However, the physical properties of the molten slag vary greatly depending on the method of taking it out, and in order to satisfy the strength to withstand the granulation due to compaction or the like as a roadbed material alone, it is necessary to keep cold (the amount of heat released by controlling the temperature). Slow cooling while suppressing) or reheating (water-cooled / air-cooled slag at 900 ° C to 1000 ° C)
It is necessary to promote crystallization by curing within a temperature range of ° C. for a certain period of time. This molten slag is expensive, cannot be used for general road business and the like in terms of cost, and is not suitable for the purpose of mass treatment of sludge because mass production is difficult.

[0004]

2. Description of the Related Art Conventionally, a stabilized soil obtained by adding lime or cement as a ground stabilizing treatment for a roadbed or the like has been widely adopted because its effect has been recognized. The applicant of the present application has further enhanced this effect, and is a soil stabilizer (hereinafter referred to as “Fe lime”) in which lime (quick lime, slaked lime and limestone powder) is mixed with fine powder of iron oxide by-produced during iron making. ), And treated soil mixed with natural soil and the like (hereinafter sometimes referred to as “Fe lime treated soil”).
He has been conducting research on improving soft ground for many years.

As a result of the research, the inventor of the present application has found that the main component composition of the sewage sludge incineration ash is similar to the main component relating to the reaction mechanism in the case of Fe lime (SiO2, Al2).
Focusing on the fact that O3, Fe2 O3, etc. are common), we developed a soil stabilizing material in which sewage sludge incineration ash and Fe lime were mixed and applied for a patent (see Japanese Patent Application Laid-Open No. 8-3552).

[0006] In the above invention, sewage sludge incineration ash by-produced in a sewage treatment plant in Fukuoka City, Fukuoka Prefecture, is used, and the effects as disclosed in the application have been confirmed. However, when sewage sludge incineration ash produced as a by-product at Saga City Saga Sewage Purification Center was used, the incineration ash (hereinafter sometimes referred to as "Saga City A") is used as shown in Table 1 and Table 1. Not only has no effect on increasing the strength, but also inhibits the reaction mechanism of the Fe-lime treated soil. That is, the CBR strength of the treated soil obtained by adding and mixing 6.5% (by weight) of Fe lime stabilizer to the soil prepared by adding the incinerated ash to the soil is inversely proportional to the amount of the incinerated ash added to the soil. Decrease.

[0007] Table 2 shows the results of a similar experiment in which ordinary cement was used in place of Fe lime. In the cement stabilized soil, the incinerated ash (A, Saga City) was used similarly to the Fe lime treated soil. It has been clarified that the addition not only has no effect on increasing the strength but also inhibits the reaction mechanism.

[0008]

The components of the sewage sludge ash from Saga City A and the sewage ash from Fukuoka City were analyzed, and the reason for such a difference was examined. Table 3 shows the results of component analysis of sewage sludge incineration ash from Saga City A. When compared with the results of component analysis of sewage sludge incineration ash in Fukuoka City (see Table 1 in JP-A-8-3552), the most different points are as follows. It was found that the carbon content (hereinafter, also referred to as “carbon”) considered to be due to incomplete combustion was contained at a value as high as 8.5 (weight)%.

This carbon is agglomerated and contained in the incinerated ash. However, when it is loosened with a fingertip, the carbon is very fine particles, and since it is an organic material in the form of soot, which is used as a raw material for black ink, it is lime-based or cement-based. Was considered to be an inhibitory factor of the reaction mechanism.
Tables 4 and 5 show the physical properties and chemical composition of the target soil (land medium) used in the experiment.

Therefore, in order to remove carbon from sewage sludge incineration ash of Saga City A, the set temperature in the furnace is set to 8 using an electric furnace.
Experiments were performed at 00 ° C. and 1200 ° C. and the burning time was changed to 10, 30, and 60 minutes, and the following results were obtained.

When the set temperature is set to 800 ° C., most of the carbon remains black as it is when the temperature returns to room temperature after burning for 10 minutes, but most of the carbon remains unchanged after burning for 30 minutes. After burning and returning to room temperature, brown and black particles were mixed. In addition, in the case of burning for 60 minutes, even if carbon almost burned and returned to room temperature, the carbon as a whole exhibited the same light brown color as the incineration ash of Fukuoka City used as a comparative example, and a very small amount of black particles was mixed.

When the set temperature is 1200 ° C., 10
In the case of burning for 30 minutes, when returning to room temperature, most of the carbon remains in the black state as it is and remains in the molten state at the bottom of the container, and in the case of burning for 30 minutes, the melting progresses further and some vitrification progresses Fused with and adhered to the bottom of the container.
Further, in the case of combustion for 60 minutes, melting and vitrification further proceeded, and when the temperature returned to room temperature, it was fused with the container and damaged.

From the results of the above visual observations, it was considered that carbon was the most removed at a set temperature of 800 ° C. for a burning time of 60 minutes.
As shown in Table 2, the carbon content (carbon) was 0.07 (weight)%, and it was confirmed that the other components did not change significantly but the carbon content was extremely reduced as compared with Table 3.

Next, the CB of the Fe-lime treated soil obtained by mixing the incinerated ash burned in the electric furnace with the soil and adjusting the material quality is described.
An experiment on the effect on R intensity was performed. The results are shown in Table 7, and it was confirmed that the carbon contained in the sewage sludge incineration ash can be used as a stabilizer for Fe-lime-treated soil by removing the carbon by burning.

Next, various experiments were conducted with the aim of improving the operation method and reducing the carbon content (carbon) at the existing facility of the Saga Sewage Purification Center. Table 8 shows the results of component analysis of the sewage sludge incineration ash (hereinafter sometimes referred to as “Saga city B”) obtained as a result. The carbon content (carbon) was 2.28 (weight)%. The electric furnace 8
Compared to 0.07% (weight)% in the case of burning at 00 ° C for 60 minutes, it is much larger than that of the conventional incinerated ash of Saga City A.

An experiment was conducted on the effect of the sewage sludge incineration ash from Saga City B on the CBR strength of the Fe-lime treated soil when the material was adjusted by mixing it with the soil. The results are shown in Table 9, which shows that the use of the incinerated ash of Saga City B as a material adjuster for the soil of Fe-lime treated soil does not have a reinforcing effect on the treated soil, but rather is a hindrance to the reaction mechanism. all right. Therefore, it has been found that it is impractical to use sludge incineration ash having this level of carbon content (more than 2%) by mixing it with Fe lime as it is.

Therefore, an experiment was conducted at the Saga Sewage Purification Center to further reduce the water content of the dewatered cake by using a coagulant such as polyiron chloride to increase the combustion efficiency and burn off the carbon contained. Table 10 shows the resulting sewage sludge incineration ash (hereinafter sometimes referred to as "Saga City C").
3 shows the results of component analysis of the electric furnace 80 shown in Table 3 with the carbon content (carbon) being 0.21 (weight)%.
A product considerably approaching 0.07% by weight in the case of burning at 0 ° C. for 60 minutes was obtained.

From the above experiment, it was found that the carbon content can be considerably reduced even in the existing facilities, but in consideration of the actual operation state and the like in the facilities,
Nearly practically impossible at present is to reduce the carbon to a state of Saga C, it is the practical to run it plans a state of about Saga B.

[0019]

Accordingly, sludge incineration ash having a carbon content of about B (more than 2%) of Saga city is directly converted to Fe
Instead of mixing with lime, various experiments were conducted on the premise that solidified cement with this incinerated ash could be used as granular aggregates and other construction materials, and will be described in detail below. Thus, the present invention was completed after confirming its practicality.

That is, cement solidified from sewage sludge incineration ash used in the present invention (hereinafter referred to as “the cement of the present invention”)
Solidified matter ”or“ sewage sludge incineration ash of the present invention
Solidified cement ". ) Is to adjust the carbon content of the sewage sludge incineration ash to 3% by weight or less, and to mix the sewage sludge incineration ash and cement in a weight ratio of incineration ash: cement of 1: 1 to 1: 3. An appropriate amount of water is added to solidify, and the uniaxial compressive strength is 100 to 200 kgf / cm.
2 (March 28th).

[0021] Then, the sewage sludge incinerated ash according to the present invention
The grain preparation material using the solidified cement as a raw material is a mixture of a granular aggregate obtained by crushing the solidified cement and a natural soil, and a fine powder of iron oxide and an Fe lime-based stabilizer made of slaked lime. is there.

On the other hand, in the stabilization method according to the present invention, a roadbed is laid with the above-mentioned grain-conditioned material, and after the compaction, individual granular aggregates are embedded in a matrix of Fe-lime-based treated soil. It is like that.

[0023]

[Function] Sewage sludge incineration ash, in which carbon (carbon) is suppressed to a certain amount or less, undergoes a chemical reaction similar to Fe lime, and when this is mixed with cement and solidified, relatively low-strength lightweight porous cement is obtained. It becomes a solid.

When the crushed granular aggregate is used by mixing it with Fe lime and natural soil, the granular aggregate is embedded in the matrix of the Fe lime treated soil and the contact surface between the surface of the granular aggregate and the matrix is formed. Hydrates are produced by the Fe-lime-based stabilizer, and the strength of the stabilized base is increased by the increase in the bonding force and the frictional resistance at the contact surface.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The solidified cement of the present invention does not require a high strength as a granular aggregate alone as in the case of using it alone as a granular roadbed material. However, since the strength of the granular aggregate and the strength of the solidified cement for producing the granular aggregate are unknown, the following various experiments were conducted to clarify this, and the applicant's past various Based on experience, the strength of cement solids and granular aggregates that can be used practically were determined.

First, an experiment was conducted on the setting of a cement solidified material containing incinerated ash as a main raw material. Based on the compounding setting, several types of cement solidified materials were mechanically crushed and mixed with a granular aggregate to mix Fe-lime-based stable treatment. An experiment was conducted on the setting of the roadbed material (hereinafter sometimes referred to as “grain-finished Fe-treated material”).

The Fe lime method referred to in the present application is based on natural soil such as sandy loam or sandy clay which can be obtained on a soft subgrade at the present position or near the site (masa soil in northern Kyushu, white sand in southern Kyushu). The standard is to construct a stabilizing layer (impervious constrained layer) to which Fe lime stabilizers are added and mixed as shown in Table 11 as shown in Table 11 as shown in FIG.

In order to improve the durability of this standard type granular roadbed due to fatigue, a grain-finished Fe-treated material has been applied to the roadbed. This is excellent in water resistance and vibration damping properties, and as a single granular roadbed material, 40 to 5 granular aggregates due to construction waste materials or the like, for which fine graining is a concern.
As it is used at a high rate of 0 (weight)%, as shown in Fig. 2, water-resistant pavement on low-lying terrain where underpasses and roads at graded intersections are flooded, or longevity in urbanized areas Applied to pavement subbase. The method of using the granular aggregate obtained by crushing the solidified cement made from sewage sludge incineration ash as a raw material of the present invention as a reinforcing material for the grain-treated Fe-treated material has been researched and developed based on this long-standing empirical technology. is there.

First, a carbon content of about 2.3 (weight)%
Using sludge incineration ash of Saga City B and sludge incineration ash of Saga City C having a carbon content of about 0.2 (weight)%, a cement solidified product was prepared by changing the mixing ratio of incineration ash and cement. In addition, by increasing the roughness of the surface of the granular aggregate, it is expected that the strength of the grain-like Fe treated layer will increase due to the increase in frictional resistance between the compacted matrix and the surface of the aggregate. A solidified cement was also prepared from a mixture of the above screenings (SC) at a dry weight ratio of 5: 2. Tables 12 to 15 show the results of both.
3 and 4 show the relationship between the unit cement amount and the unconfined compressive strength (age of 28 days).

As is clear from Tables 12 and 14, if the incinerated ash and the cement are mixed at a ratio of 1: 1, the uniaxial compressive strength is 100 kgf / cm 2 regardless of which incinerated ash is used.
It can be seen that it is possible to produce a degree of solidified cement. And, as the amount of cement increases, the uniaxial compressive strength increases accordingly. Also, as is clear from FIGS. 3 and 4, there is no significant difference in strength improvement when the incineration ash alone and the incineration ash are mixed with natural mountain crushing screenings at a ratio of 5: 2. Screening of natural mountain crushing is effective in order to obtain high-strength cement solidified material.However, for the purpose of the present invention, high strength is not required, and it is necessary to utilize more incineration ash. Is more effective.

Therefore, from the viewpoint of strength, the incinerated ash alone had a uniaxial compressive strength of 50, 100, 150. Screening of incinerated ash and natural crushed stones from the four types of 200 kgf / cm2 and from the viewpoint of increasing the frictional resistance by increasing the surface roughness of the aggregate:
The experiment was conducted with a total of five types of materials mixed at a ratio of 2 and having a uniaxial compressive strength of 100 kgf / cm 2 on the 28th day of the material.

The purpose of this experimental study can be summarized as follows. That is, in the grain-finished Fe-treated material after compaction, the low-strength granular aggregate that cannot be applied to the roadbed material by itself when mixed is completely embedded in the matrix of the Fe-lime-based treated material, thereby reducing the grain size. Is prevented and 10-7
The purpose is to determine an aggregate particle size range and a basic compounding ratio that ensure the following water permeability (cm / s).

More specifically, it is as follows. Regarding the grain-treated Fe-treated material in which four types of incinerated ash cement solidified materials with different strengths were mixed in the soil, the relationship between the strength of the granular aggregate and the CBR strength was obtained for each material age,
Calculate the optimum strength of cement solidified material. Granulated Fe treatment mixed with cement aggregate (uniaxial compressive strength of 100 kgf / cm @ 2 on 28 days old) obtained by mixing incineration ash with natural mountain crushing screenings at a ratio of 5: 2 (dry weight) The values for the timber are displayed in the above relationship diagram to evaluate the screenings of natural mountain crushing. As a comparative example, when natural mountain crushing is applied in place of the above-mentioned granular aggregate made of cement solidified material, and F
e When lime stabilizer is added C in each material age
BR intensity is obtained and compared with the case according to the present invention. In the present invention, it is confirmed that the particle size of the aggregate is coarsened immediately after the compaction or at an early stage by the agglomeration action based on the ion exchange reaction of the Fe-lime-based stabilizer on the surface of the granular aggregate by the solidified cement. To verify this, the specimens immediately after compaction and 4 days of age were subjected to an aggregate sieving test to determine the difference in the strength of the solidified cement, or the case where natural mountain crushing was applied, or
A comparative study is made with the case where no lime stabilizer is added. In addition, a comparative experiment is performed on a sample crushing adjustment method in a sieving test, and a particle size test in a case where agglomeration is dispersed using a dispersant (sodium hexametaphosphate) is performed to verify the effect of the present invention.

As a preliminary test, in order to determine the particle size range and the basic compounding ratio of the grain-finished Fe-treated material, the granular aggregate (Table 17) obtained by natural crushing shown in Table 16 was applied to the masa soil shown in Tables 4 and 5.
The curve connecting the median of the particle size range of M-25 shown in
6.0 (dry weight)% standard F relative to the mixture spiked at 0, 20, 40, 60, 80, 100 (dry weight)%.
e) Lime was added, and the compacted test, CBR test and water permeability test of the treated soil were performed.

In this test, the standard aggregate was used as the granular aggregate instead of the solidified cement made from sewage sludge incineration ash, which is the subject of the present invention, for the following two reasons. Since the difference in specific gravity between the masa soil and the granular aggregate by the standard mountain crushing is 0.2 or less, the difference in dry density mainly indicates the degree of compaction of the masa soil as a matrix, and it is easy to confirm the result. This is because even if the aggregate amount of the granular aggregate increases and the granular aggregate is directly subjected to the impact load due to the compaction, the analysis is easy because there is no fine graining in the case of the standard mountain crushing.

Tables 18 and 19 are calculation tables of the mixing ratio of the grain-treated Fe-treated material and the synthetic particle size of the masa soil and the standard crushing. Here, the coagulation action by the ion exchange reaction by the stabilizer (Fe lime) is shown. And hydrated compounds affect the aggregate particle size (Tables 20 to 22 and FIGS. 5 to 7).
eCalculation is performed by adding lime.

The following can be understood from the results shown in Table 23 and FIGS. In the relationship between the mixing ratio of the granular aggregate and the compacted dry density (however, the compaction frequency is 67 times for each layer × 3 layers), the density increases linearly with the mixing ratio of the granular aggregate up to the mixing ratio of about 50%. , 60% or more, the density does not increase or decrease so much. Since there is not much difference in specific gravity between the masa soil and the aggregate, the degree of compaction of the matrix is increased by the aggregate at first, but when the aggregate mixing ratio exceeds 60%, the aggregate and the aggregate come into contact and the matrix is tightened. This is probably due to the inhibition of compaction. The relationship between the mixing ratio and CBR (4 days after tamping)
Even when the mixing ratio is 0%, the strength is relatively high due to the reaction mechanism. However, when the mixing ratio is 20%, the strength is further increased by about 20%.
A relatively high value is shown. However, at a mixing ratio of 40% or more, the strength decreases linearly with an increase in the mixing ratio, and the mixing ratio 1
In the case of 00% (standard mountain crushing 94% + Fe lime 6%), the value is lower than that in the case of the granular aggregate alone. In relation to the mixing ratio and water permeability, the mixing ratio is 0% (masa soil 94% +
Fe lime 6%) shows a value of 5.5 × 10 -7, and the mixture ratio of 20% shows a slightly lower value, but a mixture ratio of 40% shows a value of 8.4 × 10 -7. As the mixing ratio increases, the hydraulic conductivity increases linearly. However, mixing ratio 1
8.0% for 00% (standard crushed rock 94% + Fe lime 6%)
It shows a value of 10 @ -5, which is much lower than the water permeability of the granular aggregate alone without the addition of Fe lime stabilizer.

From the results of the above preliminary test, it is considered that the desirable particle size range and the basic compounding ratio in the present invention are as follows. The lower limit of the desirable particle size range in the present invention is a particle size curve with an aggregate mixing ratio of 60% in FIG. 11, and the upper limit is similarly a particle size curve with an aggregate mixing ratio of 0%. The basic blending ratio is the blending of the synthetic particle size of 40% shown in Table 18,
That is, [mass earth 56.4% + granular aggregate 37.6% + F
e-lime 6.0%]. Therefore, in the tests described below, the particle size range and the basic compounding ratio were used as a reference. The test procedure and results are as follows. However, from the results of FIGS. 8 to 10 described above, it is practically feasible at an aggregate mixing ratio of 20% to 60%.
It seems that the best results are obtained at around 5% to 45%.

1) Adjustment by Specific Gravity and Water Absorption 1-1) Adjustment of Volume Ratio by Correction of Specific Gravity The granular aggregate obtained by mechanically crushing the cement solidified material from sewage sludge incineration ash of the present invention is shown in Table 24. The specific gravity is very small and the water absorption is very large as compared with ordinary aggregate such as natural mountain crushing. In the grain-base Fe-treated roadbed using this as a granular aggregate, the mixing ratio is corrected according to the specific gravity of the aggregate used as shown in Table 25, and the volume of each material with respect to the total volume of the compacted grain-base Fe-treated layer is corrected. It is important to control the volume. Since this is similar to the fact that the basic properties of the asphalt mixture are greatly affected by the volume of the material used, the method of adjusting the volume ratio by the specific gravity correction conforms to the asphalt pavement outline.

1-2) Adjustment to Water Absorption As shown in Table 24, the granular aggregate made of cement solid has a very high water absorption.
In the production of the e-treated material, the granular aggregate is sufficiently mixed with water in advance and mixed in a dry state on the surface. Not only for the purpose of adjusting the compaction water content ratio, but also for the replenishment of water essential for promoting the coagulation action by the ion exchange reaction by the Fe-lime-based stabilizer at the contact surface between the surface of the above-mentioned granular aggregate and the matrix. Because it has a purpose. However, since the basic blending is performed in all dry weight percentages (%), the dry weight is converted to the wet weight based on the definition of the water content of the soil in the production of the treatment material.

2) Test method for grain-treated Fe-treated material Masasa soil shown in Tables 4 and 5 (however, adjusted to the grain size shown in Table 18) and the target obtained from FIGS. 3 and 4 and Tables 12 to 15 Uniaxial compressive strength (March 28th: kgf / cm2) 5
A target unconfined compressive strength of 100 kgf is obtained by using as an aggregate a cement solidified material using 0,100,150,200 incinerated ash as an aggregate, and a mixture of incinerated ash mixed with natural mountain crushing screenings at a ratio of 5: 2. / Cm2 (however, M-
25 adjusted to a particle size of 25) and Table 11
The standard Fe lime shown in (1) is added and mixed. Table 16 shows comparative examples of granular aggregates using these cement solids.
A natural Fe-crushed material was tested using natural mountain crushing (M-25) shown in Table 2 and recycled concrete aggregate (RM-25) shown in Table 26.

2-1) CBR test The CBR test of the grain-treated Fe-treated material is almost in conformity with the CBR test of the stabilized mixture of the pavement test method handbook (published by the Japan Road Association). Only use the soil available at the current location or near the site, and use Fe on a soft subgrade.
On the premise that it is constructed on a constrained layer with lime-treated soil,
It was as follows. The number of times of compaction is 67 for each layer.
e The amount of lime stabilizer added was 6.0 (dry weight)%.
The compacted water content is determined by adding a predetermined amount of F
(e) It depends on the water content when the lime stabilizer is added. The specimens were cured immediately after compaction without water infiltration and continuously immersed immediately after compaction.
The standard date is 28 days.

2-2) Screening test of compacted specimens In general, when granular aggregate is applied to the granular roadbed method or the grain size adjusting method, there is a concern that the strength may be reduced due to the reduction in grain size due to compaction or the like. The test specimen sieving test after compaction is performed. Therefore, in the present invention, an aggregate sieving test is carried out by the following method in order to confirm that the aggregate particle size is coarsened by the agglomeration effect of the ion exchange reaction on the surface of the granular aggregate immediately after compaction or in the initial stage. Was done. Immediately after compaction, loosen the specimen after non-flooding and CBR penetration test of 4 days of age, put about 1 kg in a plastic bag, tie it with a string, and drop it 30 times onto a concrete floor from a height of 1.5 m. After that, the loosened sample is oven-dried at a constant temperature of 100 ° C. to a constant mass, and the sample is rinsed with water on a standard mesh sieve 75 μm to wash out fine particles, and then oven-dried to conduct a sieving test. . Similarly, about 1 kg of a furnace-dried sample dropped from a height of 1.5 m and loosened was sampled, and collected by the Japan Society of Soil Engineers (JS
FT 131-1990) According to the soil particle size test method, a saturated solution of sodium hexametaphosphate was used as a dispersant in a dispersing apparatus, followed by washing with water, drying, and a sieving test.

3) Test Results and Consideration of Grain-Fe Treated Material 3-1) Test on Material Age and CBR of Grain-Fe Treated Material Tables 27 and 28 show sewage sludge incineration ash (Saga B) and the same (Saga) Age 0, 4 and 7 of grain-like Fe-treated material with reinforcing cement granulated aggregate obtained by mixing screenings at a ratio of 5: 2 with simple substance of city C) and incineration ash
A list of CBR test results on days 14, 14 and 28 is shown.
In addition, as a comparative example of the granular aggregates using these cement solidified products, CBR tests using natural crushed rocks (M-25) and recycled concrete aggregates (RM-25) as shown in Table 29, and the case of using masa earth alone. The result list is shown. However, in the experiment of the comparative example, material age 7 days was omitted.

The following can be seen from the results of Tables 27 to 29. The solidified cement of incinerated ash is shown in FIGS.
From Table 15, the indicated composition was determined for each of the target strengths, and was manufactured. The treated material using natural mountain crushing has the lowest compaction water content of 8.2% and the highest compacted dry density of about 2.07 g / c.
m3, and the highest tamped water content is about 23% in the treated material using the granular aggregate by the cement solidified incineration ash.
The compacted dry density was about 1.59 g / cm3. Nevertheless, the increase in water content due to immersion was at most about 3.5% in the 28-day immersion. This is considered to indicate that the mixed granular aggregate is completely embedded in the Fe-lime treated soil and is in an impermeable layer. In addition, the treated material of masa earth alone in the portion passing through the standard sieve 13.2 mm without the addition of the coarse aggregate performed as a comparative example shows high strength.
As shown in Fig. 5, the plasticity index is about 12, and the fine-grained portion is relatively weathered, but contains a relatively large amount of coarse aggregate of 2 mm or more, about 25%, in terms of grain size.

FIG. 12 shows granular aggregates of cement sewage sludge incineration ash (Saga City B) and the same (Saga City C) in which screenings are mixed with incineration ash alone and incineration ash at a ratio of 5: 2. Shows the relationship between the CBR strength at each material age and the target strength of the reinforcing material from the grain-tone Fe-treated material CBR test using as a reinforcing material, and the following can be seen from the results. The reinforcing effect differs depending on the strength of the solidified cement of incineration ash, and the difference increases with the progress of the age of the treated material. As the age of the treated material advances, the CBR strength of the treated material increases in proportion to the strength of the cement solidified material to be mixed. That is, as is apparent from FIG. 12, the slope of the curve representing the relationship between the strength of the cement solid to be mixed and the CBR strength of the treated material becomes steeper as the material age advances. As an overall tendency, as the age of the treated material progresses, the unconfined compressive strength of the cement solidified material (age 28 days: kgf / cm
The gradient changes depending on whether 2) is 100 or less or 100 or more. Therefore, the target strength of the solidified incinerated ash cement as a reinforcing material for the grain-finished Fe-treated material is preferably as large as 100 kgf / cm 2 or more. It is sufficient if the unconfined compressive strength on the 28th is about 100 kgf / cm2 to 150 kgf / cm2. In addition, same as sewage sludge incineration ash (Saga City B) (Saga City C)
So there is not much difference. Therefore, it can be said that if the carbon content (carbon) is 3.0 (weight)% or less, it can sufficiently withstand practical use without completely removing carbon. As for natural mountain crushing screenings, a tentative effect is recognized in increasing the strength of the treated material, but the required strength can be obtained without mixing natural mountain crushing, and the sewage sludge incineration ash can be recycled. For the purpose of the present invention to utilize, it is not necessary to basically use natural mountain crushing screenings.

3-2) Test on Coarse Graining of Grain-Fed Treated Material Table 20 shows the cement solidified product using sewage sludge incineration ash (B, Saga City) immediately after compaction of the grain-treated Fe-treated material and on the 4th day of material age. It is a list of the sieving test of the compacted specimen. Table 21 shows the same results for sewage sludge incineration ash (C, Saga City), and Table 22 shows the same results for those using natural mountain crushing and cement concrete recycled aggregates performed as comparative examples. The following can be seen from the results. Granular aggregate made of solidified incineration ash cement mixed with grain-like Fe treated material has a uniaxial compressive strength (28 days old) of 50 kg.
Even with a strength as low as f / cm 2, no crushing and fine graining due to CBR compaction has occurred. Conversely, immediately after the mixing and compacting, or very early, agglomeration occurs due to the ion exchange reaction of the Fe lime stabilizer on the surface of the granular aggregate and the contact surface using the Fe lime-treated soil as a matrix, resulting in agglomeration. (Coarsening) has occurred.

FIG. 5 shows the grain size curves immediately after and 4 days after CBR compaction of the grain-treated Fe-treated material using granular aggregates made of cement solidified sewage sludge incineration ash, and FIG. FIG. 7 shows a grain size curve as a comparison for the grain-finished Fe-treated material in the case where crushing was used and in the case where recycled concrete aggregate was used. From this, the following can be understood. There is almost no difference in the particle size after compaction when using granular aggregates of solidified cement of sewage sludge incineration ash (Saga City B) and the same (Saga City C). However, compared with conventional natural mountain crushing and recycled concrete aggregate, aggregates due to agglomeration are large as a whole, and the difference between the particle size before the test and the particle size of 4 days old is a standard sieve of 2.36 m.
Approximately 18% in the comparative example, and cement solidified incineration ash (target uniaxial compressive strength 50 kgf / cm 2)
There is a difference of less than twice at about 30%. Further, the present invention is characterized in that there is a great difference in agglomeration due to the agglomeration action of fine particles. In particular, with a standard sieve of 0.075 mm, the granular aggregate of natural crushing and concrete is almost the same as before the test or slightly increased to 1
In contrast to 0 to 13%, the granular aggregate made from the solidified incinerated ash cement has 2 to 4%, and there is a large difference in the coagulation action due to the ion exchange reaction. It can be considered that this difference in the agglomeration action is the water retention effect of the solidified incinerated ash cement on the grain-like Fe-treated material. In other words, granular aggregates from incinerated ash cement solidified
This is because, as shown in Table 24, the grain-finished Fe-treated material is mixed and manufactured with a high water absorption amount of 35 to 50% and a state of containing water in a saturated state (surface dry saturated state). On the other hand, the water absorption of the natural mountain crushing of the comparative example is 0.82% as shown in Table 16, and the water absorption of the recycled concrete aggregate shown in Table 26 is at most 7.38%. In addition, the unitary cement amount (kg / m3) of the cement solidified product is the target uniaxial compressive strength (material age 2) as shown in Tables 12 to 15.
8th: qu = kgf / cm2) 310-34 at qu50
0, qu100 = 410-450, qu150 = 520
It is not small at ２００560, qu200 and 600-650 at qu200. Therefore, the water content is a source of water indispensable for the ion exchange reaction, and the water contains reactive components such as free lime, which may be involved in the reaction mechanism of the subsequent Fe lime. .

From the above results, the reaction mechanism of the grain-treated Fe-treated material is considered as a reinforcing material using a granular aggregate made of cement solidified from sewage sludge incineration ash having a low strength that cannot be used alone as a roadbed material. It was confirmed that it was promoted. In addition, the solidified cement of the present invention can be used for various purposes by itself because it is porous, and when it is used as a granular aggregate, it is completely embedded in Fe-lime-treated soil as a matrix. Thus, it was confirmed that the hydraulic conductivity can be extremely reduced.

[0050]

Next, an embodiment of the present invention will be described. [Example 1] Method for producing cement solidified product using sewage sludge incineration ash as raw material Sewage sludge generated at Saga City Sewage Purification Center is dewatered to a water content of about 490%, and this is incinerated at Saga City Sewage Purification Center. After being kept at an incineration temperature of 820 ° C. for 3 seconds, hot air drying was performed, and granular incineration ash having a carbon content (carbon) of about 2% and a diameter of about 0.7 mm was collected by a dust collector. Then, the recovered incineration ash, cement and water were mixed and solidified by almost the same weight to produce a solidified cement.

The unconfined compressive strength of the cement solid measured on 28 days of age was about 110 kgf / cm 2. The solidified cement has a specific gravity of about 1.6 and a water absorption of about 47.
%, The specific gravity is about 2/3 that of natural aggregate and recycled concrete aggregate, and the water absorption is about 7 to 50 times, which is extremely large. Therefore, this cement solidified material can be used as a raw material for the following grain preparation materials, and can also be used as a substitute for volcanic debris, etc. by utilizing its light weight and high water retention, and when used for a ground or athletic field, a well drained ground, etc. Can be provided.

Example 2 Method for Producing Grain-Treated Material The solidified cement produced in Example 1 was mechanically crushed into granular aggregate. Table 17 shows the particle size range of this granular aggregate.
The particle size is adjusted so as to be in the range of the coarse aggregate (M-25). Then, the granular aggregate, slaked lime and fine powder of iron oxide by-produced during iron making were mixed at a dry weight ratio of 5: 5: 3 to obtain a grain-treated material. This granular material has already been mixed with a granular aggregate, and can be used as a roadbed material or the like after being mixed with an appropriate amount of natural soil.

[Example 3] Method of applying the stabilization treatment method The granulated material produced in Example 2 and masa earth are mixed at a dry weight ratio of 6: 4. The incinerated ash was rolled so as to be about 170 kg (dry weight) per 1 m <3> of the processed volume of the stabilized layer, and the compacted and stabilized ground was obtained. The CBR value of this stabilized roadbed was measured to be about 260% on 4 days and about 570% on 28 days. The specific gravity was around 1.6.

[0054]

As described above, the cement solidified from sewage sludge incineration ash used in the present invention has a carbon content of the sewage sludge incineration ash of 3 (weight)% or less. The sewage sludge incineration ash and cement are mixed at a weight ratio of incineration ash: cement in a ratio of 1: 1 to 1: 3, an appropriate amount of water is added thereto, and the mixture is solidified to have a uniaxial compressive strength of 100 to 200 kgf / cm.
2 (March 28th), the sludge incineration ash of a normal sewage treatment plant can be easily recycled for the following uses without special treatment.

[0055] Then, the sewage sludge incinerated ash according to the present invention
Since the grain preparation material using the cement solidified material as a raw material is a mixture of the granular aggregate and the natural soil obtained by crushing the cement solidified material, a fine powder of iron oxide and an Fe lime-based stabilizer made of slaked lime are mixed. Sewage sludge incineration ash can be used in large quantities.

Further, according to the stabilization method according to the invention of the present invention, a roadbed is laid with the above-mentioned grain-conditioned material, and after the compaction, the individual granular aggregates are embedded in Fe-lime-based treated soil. As a result, the granular aggregate can be used as a roadbed material even if the strength is not so high, and the strength (particularly, the strength (particularly, Initial strength) can be greatly increased.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

[Table 4]

[0061]

[Table 5]

[0062]

[Table 6]

[0063]

[Table 7]

[0064]

[Table 8]

[0065]

[Table 9]

[0066]

[Table 10]

[0067]

[Table 11]

[0068]

[Table 12]

[0069]

[Table 13]

[0070]

[Table 14]

[0071]

[Table 15]

[0072]

[Table 16]

[0073]

[Table 17]

[0074]

[Table 18]

[0075]

[Table 19]

[0076]

[Table 20]

[0077]

[Table 21]

[0078]

[Table 22]

[0079]

[Table 23]

[0080]

[Table 24]

[0081]

[Table 25]

[0082]

[Table 26]

[0083]

[Table 27]

[0084]

[Table 28]

[0085]

[Table 29]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a standard pavement structure of the Fe lime method.

FIG. 2 is a cross-sectional view showing an example of a pavement configuration in which a grain Fe-treated material is applied to a roadbed.

FIG. 3 is a graph showing the relationship between the unit cement amount of cement solidified sewage sludge incineration ash of Saga City B and the uniaxial compressive strength.

FIG. 4 is a graph showing the relationship between unit cement amount of cement solidified sewage sludge incineration ash of Saga City C and unconfined compressive strength.

FIG. 5 is a graph showing a change in the particle size of a grain-treated Fe-treated material using a granular aggregate of a solidified cement of sewage sludge incineration ash (target unconfined compressive strength = 50 kgf / cm 2, material age).

FIG. 6 is a graph showing a change in particle size of a grain-like Fe-treated material using natural mountain crushing (M-25).

FIG. 7 is a graph showing a change in particle size of a grain-like Fe-treated material using recycled concrete aggregate (RM-25).

FIG. 8 is a graph showing a relationship between a granular aggregate mixing ratio and a compaction density.

FIG. 9 is a graph showing a relationship between a granular aggregate mixing ratio and CBR.

FIG. 10 is a graph showing a relationship between a granular aggregate mixing ratio and a hydraulic conductivity.

FIG. 11 is a graph showing the mixing ratio of granular aggregates and the composite particle size curve in the grain-treated Fe-treated material by masa soil and standard mountain crushing.

FIG. 12 is a graph showing CBR test results of a grain-like Fe-treated material in which granular aggregate made of cement solidified sewage sludge incineration ash is used as a reinforcing material.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09K 17/02 C09K 17/06 P 17/06 17/10 P 17/10 E01C 5/06 E01C 5/06 E02D 3/02 103 E02D 3/02 103 3/12 102 3/12 102 (C04B 28/02 // (C04B 28/02 18:10 Z 18:10 14:10 Z 14:10 22:06) Z 22:06) 111: 40 111: 40 C09K 103: 00 C09K 103: 00 B09B 3/00 ZAB (56) Reference JP 9-47741 (JP, A) JP 8-3552 (JP, A) JP 9-235151 (JP, A) JP-A-9-301750 (JP, A) JP-A-11-322401 (JP, A) JP-A-10-226556 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C04B 18/10 C09K 17/02 C09K 17/06 C09K 17/10

Claims (2)

(57) [Claims] 1. The sewage sludge incineration ash has a carbon content of 3% by weight.
The sewage sludge incineration ash and the cement are mixed in a ratio of 1: 1 to 1: 3 by weight of the incineration ash: cement, and an appropriate amount of water is added to solidify the ash and the uniaxial compressive strength to 1
Seme was a 00~200kgf / cm2 (wood age 28 days)
Acid mixture into a mixture of granular aggregates
Fe-lime-based stabilizer consisting of fine powder of iron fossil and slaked lime
Grain halftone processing material sewage sludge incineration ash using cement solidified product as a raw material, characterized in that the engagement. 2. A stable base characterized by laying a roadbed with the grain-conditioned material according to claim 1 , and after rolling, each granular aggregate is embedded in a matrix of Fe-lime-based treated soil. Processing method.