JP2007197902A - Improved soil, improved soil manufacturing method and paper sludge - Google Patents

Abstract

The present invention provides an improved soil that is low in cost because the amount of used paper is small and has excellent strength and durability equal to or better than a fiber-solidified soil using waste paper.
The improved soil is made by adding and mixing paper sludge, waste paper crushed material, and cement-based solidified material to a high water content mud soil. The uniaxial compressive strength increases as the amount of used paper increases, the fracture strain achieves the target value when the amount of used paper is 20-50 kg / m ³ , and the deformation coefficient almost satisfies the target value with the same range as the lower limit. The PS fiber solidified soil has high durability against repeated drying and wetting, is excellent in strength, and can sufficiently withstand use as a fill material.
[Selection] Figure 10

Description

  The present invention provides an improved soil excellent in strength characteristics and deterioration durability obtained from a high water content mud soil having no uniaxial compressive strength such as construction sludge, a method for producing the same, and sludge for the production of the improved soil. The present invention relates to a paper sludge suitable as an improved material to be added.

  Despite the fact that nearly 10 million tons of construction sludge is discharged annually, the recycling rate is low, and most of the sludge is industrial waste “sludge” except for those that are reused in intermediate treatment facilities. They are either dehydrated or taken directly to the final disposal site.

  However, the shortage / remote of disposal sites is a serious problem, and the illegal dumping of construction sludge has ceased due to the burden of transportation costs, and the impact of pollution load on the global environment has become a major problem. The effective use of is currently desired.

  Therefore, the inventors of the present application, as disclosed in the following Patent Document 1, in order to recycle sludge as a banking material having sufficient quality characteristics, waste paper crushed material that is a fibrous material in sludge and sludge and We have developed a technology to recycle high water content mud with the addition of polymer improvers.

  As a result of uniaxial compression test and crushing tensile test using the improved soil produced by this construction method (hereinafter referred to as fiber-solidified soil), the fiber-solidified soil has only cement-based solidified material in the sludge. Compared with the conventional solidified soil that has been added and mixed, it was confirmed that the fracture strain and residual strength are large and have a tenacious property.

Moreover, when using the fiber solidified soil or the solidified soil as an embankment material, these sediments are affected by weather fluctuations, that is, by repeated wet and dry. According to the results of repeated wet and dry experiments using fiber-solidified soil and solidified soil, the solidified soil deteriorates with the progress of the cycle and the uniaxial compressive strength decreases. It was confirmed that even when subjected to repeated wet and dry cycles, it hardly deteriorates and exhibits high durability.
JP 2004-278045 A

A major feature of the above-described conventional method for producing a fiber-solidified soil is that a waste paper crushed material is added to a high moisture content mud and the mud is solidified without being subjected to a dehydration step. Here, the amount of waste paper added is given as a function of the water content ratio. However, for example, when it becomes a considerably high water content mud such as 500%, it is necessary to add a large amount of waste paper of 90 kg per 1 m ^{3 of} mud. Since used paper is greatly affected by fluctuations in market prices, according to the fiber-solidified soil and its manufacturing method, when the amount of used paper increases, construction costs are not stabilized due to fluctuations in the price, There is also a risk of increasing costs.

  Accordingly, the present invention does not use waste paper that is easily affected by price fluctuations, or is low cost because the amount used is small, and has excellent strength equal to or better than the fiber-solidified soil using waste paper, and An object of the present invention is to provide an improved improved soil having durability and an effect of further promoting recycling of used paper to reduce the burden on the environment, a method for producing the same, and a powdery paper sludge that can be suitably used for them. It is said.

  The improved soil described in claim 1 is characterized in that paper sludge and cement-based solidified material are added to and mixed with high water content mud soil.

  The improved soil described in claim 2 is characterized in that paper sludge, waste paper crushed material, and cement-based solidified material are added to and mixed with high water content mud soil.

The improved soil according to claim 3 is characterized in that, in the improved soil according to claim 1 or 2, the added amount of the paper sludge is 50 to 105 kg / m ³ in a ratio to the high water content mud soil. .

The improved soil according to claim 4 is characterized in that, in the improved soil according to claim 2, the amount of the waste paper crushed material is 10 to 65 kg / m ³ in a ratio to the high water content mud soil.

  The improved soil according to claim 5 is the improved soil according to claim 1, 2, 3, or 4, wherein the paper sludge removes moisture from a mixture of moisture and solid sludge discharged in the waste paper recycling process. It is characterized by being a powder obtained by pulverizing this.

  In the method for producing the improved soil according to claim 6, paper sludge is added to the high water content mud and mixed without adding the polymer-based improving material and auxiliary agent, and then the cement-based solidifying material is added. It is characterized by mixing and then curing until a desired strength is developed.

The method for producing improved soil according to claim 7 comprises adding high-water content mud soil with paper sludge and 10-65 kg / m ³ waste paper crushed material at a ratio to the high water content mud soil, and improving the polymer-based improved material and auxiliary material. It is characterized by mixing without adding an agent, then adding and mixing a cement-based solidifying material, and then curing until a desired strength is developed.

  The paper sludge described in claim 8 is an improved substance added to a high water content mud to improve the strength characteristics / deterioration durability of the mud. It is characterized by being a powdered product obtained by removing moisture from a sludge mixture.

  The improved soil described in claim 9 is obtained by adding at least one fibrous material selected from the group consisting of crushed waste paper and paper sludge and cement-based solidified material to a high water content mud soil, It is characterized by mixing without adding an auxiliary agent.

  According to the improved soil described in claim 1, a conventional fiber material in which waste paper is added at low cost without using waste paper having a large price fluctuation while effectively using paper sludge which is waste of waste paper recycling. High durability and strength characteristics equivalent to the solidified soil can be obtained.

  According to the improved soil described in claim 2, the paper sludge, which is a waste product of waste paper recycling, is effectively used, and the waste paper having a large price fluctuation is reduced, and the waste paper is added while reducing the cost. High durability and strength characteristics equivalent to those of conventional fiber-solidified soil can be obtained.

  According to the improved soil described in claim 3, it is possible to optimize the amount of the paper sludge added to the improved soil according to claim 1 or 2 and maximize the above effects.

According to the improved soil described in claim 4, in the improved soil according to claim 2, the amount of the crushed waste paper is 10 to 65 kg / m ^{3 in} a ratio to the high water content mud soil, Compared to the solidified soil, the amount of used paper can be greatly reduced to reduce costs.

  According to the improved soil described in claim 5, the paper sludge used in the improved soil according to claim 1 or 2 or 3 or 4 is a mixture of moisture and solid sludge discharged in the recycling process of waste paper. Since an easy-to-handle powder that is pulverized after removing water is used, manufacturing operations performed on site are simple and easy.

  According to the method for producing the improved soil described in claim 6, the waste paper recycling waste is effectively utilized, and the waste paper is added at low cost without using waste paper having a large price fluctuation. High durability equivalent to that of the fiber-solidified soil can be obtained, and further, since no polymer-based improving material is used, the same performance as that of the conventional fiber-solidified soil can be obtained.

  The method for producing the improved soil according to claim 7 uses the conventional fiber while reducing the cost by reducing the amount of used paper whose price fluctuates greatly while making effective use of paper sludge, which is waste of recycled paper. High durability equivalent to that of the solidified soil can be obtained. Further, since no polymer-based improving material is used, the same strength as that of the conventional fibrous solidified soil can be obtained.

  Since the paper sludge described in claim 8 is a powdered product obtained by pulverizing a mixture of water and solid sludge discharged from the waste paper recycling process, it is added to the high water content mud and improved soil. As an improved material, it is easy to transport and handle at the manufacturing site.

  The improved soil described in claim 9 is obtained by adding at least one fibrous material selected from the group consisting of crushed waste paper and paper sludge and cement-based solidified material to a high water content mud soil, Since mixing is carried out without adding an auxiliary agent, there is no inconvenience that the hydration reaction of the cement is hindered by the addition of the polymer-based improving material and auxiliary agent, and the strength of the obtained treated soil does not decrease. .

1. Experiment conducted in the embodiment of the present invention The present inventor is a paper sludge generated from a recycled paper manufacturing process as a material (improving material) for improving a high water content mud soil having no uniaxial compressive strength such as construction sludge. (Hereinafter referred to as PS).

  That is, in the embodiment of the present invention, as described in detail below, PS is added to mud instead of waste paper to be crushed, PS-containing solidified soil (hereinafter referred to as PS solidified soil), and PS and waste paper crushing PS solidified soil with PS added to both mud soil (hereinafter referred to as PS fiber solidified soil), and the strength characteristics and durability of the fiber solidified soil (recycled waste paper) An experiment was conducted to quantitatively evaluate the strength characteristics and durability compared to the strength characteristics and durability of the mud soil) and the solidified soil (mud soil added with a cement-based solidifying agent).

  In addition, experiments were also conducted for the purpose of verifying the effects of polymer modifiers and auxiliaries on the strength properties and durability of the treated soil. These agents are intended to create agglomerated structures that enable immediate transportation of the treated soil, and have been considered to be indispensable agents in the field where immediate transportation is necessary. The effects of these agents on the strength properties and durability of the treated soil have not been clarified. If these chemicals do not affect the strength characteristics and durability of the treated soil, there is sufficient temporary storage and curing period, and there is no need to add chemicals at sites that do not require immediate transportation. As a result, the construction cost may be reduced. Therefore, the present inventor also experimentally examined the difference in strength characteristics and durability depending on the presence or absence of a drug.

2. Paper sludge Paper is a consumer material that is produced, consumed, and discarded in large quantities, and is still one of the largest materials that accounts for about 25% of general waste disposal. For this reason, recycling of waste paper is becoming more and more important from the viewpoints of effective resource utilization, waste reduction, and forest resource conservation. Currently, the paper industry is working on the goal of "reducing the waste paper utilization rate to 60% by 2005" based on the Law for Promotion of Effective Utilization of Resources.

  On the other hand, when recycling pulp fiber, which is used as a raw material for recycled paper, waste paper recycling is a waste paper waste (PS) that contains inorganic fillers, short pulp fibers that do not become paper, and deinked ink components. Since it is discharged as waste, paper sludge (PS) tends to increase as the waste paper utilization rate rises. Paper sludge generated from the manufacturing process reaches more than tens of thousands of tons per year at the factory and is currently incinerated or landfilled. However, due to difficulties in securing land, increased processing costs, and environmental problems, the purpose is to recycle. Immediate measures are desired.

  Accordingly, the first object of the present invention is to establish a recycling system that uses PS as an alternative to waste paper and effectively uses construction sludge and sludge as described above. The PS used in this experiment was collected from a recycled paper factory in Miyagi Prefecture, and its safety was determined according to environmental standards related to soil contamination (standards that should be maintained in order to protect human health and protect the living environment). After confirming the sex, it was subjected to an experiment. The component mass ratio of PS used in the experiment is shown in FIG.

  As shown in FIG. 1 (a), the PS in the initial state has 65% of the mass of moisture and 35% of solid sludge. This solid sludge. Since it is thought that it is composed of organic substances (cellulose) and inorganic substances (fillers, etc.), the result of analyzing PS by drying and evaporating moisture using a thermogravimetric / differential thermal analyzer (TG-GTA) is shown in FIG. b). As shown in this figure, 45% of the total solid sludge was organic and 55% was inorganic. Further, as a result of analyzing the components by X-ray topography (XRT), it was confirmed that the inorganic substances contained components such as talc, kaolin, calcium carbonate and the like.

  By the way, since the paper sludge (PS) discharged from the recycled paper factory contains a considerable amount of moisture as shown in FIG. 1 (a) in the initial state, it cannot be used as a substitute for waste paper waste. The inventor thought. Therefore, in the present invention, the collected PS was dried in the sun, and then loosened with an iron bee to create a PS that can be used as a substitute for waste paper crushed material. The PS created by the above process is shown in FIG. Hereinafter, PS added to the mud in this example refers to powdered paper sludge generated by treating liquid paper sludge discharged from a recycled paper factory in the above-described process.

3. Preparation of each treated soil (each specimen of the present invention and comparative product) used for the experiment
3.1 Materials used Simulated muddy water was used to create the specimens. The reason for using simulated muddy water is as follows. That is, mud such as actual construction sludge and sludge may contain organic substances (humic acid, etc.) that are solidification inhibitors by the solidifying material, and the test results may vary due to the influence of this organic substance. . Therefore, simulated muddy water was used to suppress the data variation due to the organic matter. In this experiment, inorganic soil particles were used and mud made by mixing clay and silt at a certain ratio. In the mud production method, clay and silt were mixed at a ratio of 40:60 (dry mass ratio), and the mixture was adjusted with water to produce sludge having a water content of 105% and 150%. The density of the soil particles is 2,623 [g / cm ³ ].

  As the fibrous material, used was newspaper waste paper that was cut to about 1.0 cm square. Anionic polymer polyacrylamide (manufactured by Ternite Co., Ltd .: trade name Bonteran-P) was used as the polymer improver. As the auxiliary, an inorganic flocculant (manufactured by Ternite Co., Ltd .: trade name Bonteran-L) was used.

3.2 Specimen vacation creation procedure Before explaining the specimen creation procedure, the definition of each treated soil is shown.
1) Solidified soil: treated soil in which only cement-based solidified material is added to and mixed with sludge (comparative product)
2) Fibrous solidified soil: treated soil in which waste paper crushed material and polymer improver / auxiliary are added to sludge, and cement solidifier is added and mixed (comparative product)
3) PS solidified soil: treated soil with PS and polymer improver / auxiliary added to sludge, and cement solidifier added and mixed (product of the present invention)
4) PS fiber solidified treated soil: treated soil in which PS and crushed paper and polymer improver / auxiliary are added to sludge, and cement solidified material is added and mixed (this product).
5) Fibrous solidification processor (no chemicals): treated soil in which waste paper crushed material is added to sludge and cement-based solidifying material is added and mixed (product of the present invention)
6) PS solidified soil (without chemicals): treated soil with PS added to sludge and cement solidified material added and mixed (product of the present invention)
7) PS fiber solidified treated soil (no chemicals): treated soil in which PS and waste paper crushed material are added to sludge and cement solidified material is added and mixed (product of the present invention).

  Each specimen mentioned above was created using a method according to "Development of advanced treatment and utilization technology for construction sludge (banking group) final report on durability of construction sludge improved soil" (issued in March 1997). It was. Fig. 3 shows the flow of specimen preparation. Here, the details of the procedure for creating PS solidified soil and PS fiber solidified soil (without chemicals) are described.

"Procedure for creating PS solidified soil"
1. First, as described above, clay and silt are mixed at 40:60 (dry mass ratio), and the water content is adjusted by adding water.

2. Add the amount of PS, polymer modifier and auxiliary agent shown in Table 1 to the sludge whose water content has been adjusted, and stir and mix. According to the knowledge based on a separate experiment of the present inventor, the optimum addition amounts of the polymer-based modifier and the auxiliary agent are 1.0 [kg / m ³ ] and 7.0 [kg / m ³ ], respectively. However, since nonuniform stirring is unavoidable in actual on-site processing, it is better to set 20% higher. Therefore, this time, considering the field applicability, the addition amounts of the polymer modifier and the auxiliary agent were set to 1.2 [kg / m ³ ] and 8.6 [kg / m ³ ], respectively.

 3. Next, add cement-based solidifying material and mix. The solidifying material is added with a fixed addition amount for each water content ratio.

 4. As the initial curing, put the above treated soil in a container, seal it, and leave it at 20 ± 3 ℃ for 3 days.

 5. After initial curing, prepare a specimen. The specimens were prepared according to JCAS L-01: 2003 (Cement Association Standard Test Method) “Test Method for Stabilized Soil with Cement-Based Solidified Material”. For the preparation of the specimen, a standard mold (specimen preparation container) having a diameter of 5 cm and a height of 10 cm was used.

 6. Cover the mold with a sealant to prevent moisture from evaporating from the specimen and cure at 20 ± 3 ° C for 28 days. The procedure for preparing PS solidified soil (without chemicals) was changed in six ways as the blending conditions shown in Table 1 without adding the chemicals in the above step 2.

"Procedure for creating PS fiber nationalized soil (no drugs)"
1. Mix clay and silt at 40:60 (dry mass ratio) and adjust the water content by adding water.
2. Add PS and waste paper to sludge with adjusted water content, and stir and mix.
3. Next, add cement-based solidifying material and mix. In addition, the addition amount of PS, waste paper crushed material, and cementitious solidifying material was changed in 11 ways according to the blending conditions shown in Table 1 according to the water content ratio.

  The specimen preparation procedure for the solidified soil and the fiber solidified soil is different in that PS is not added in step 2 described above.

4). Dry and wet repeated test
4.1 Test method First, durability against repeated wet and dry conditions was examined. As shown in Table 2, the test method is “Advanced Construction Sludge Treatment and Utilization,” which was jointly developed by the former Ministry of Construction Civil Engineering Research Institute (currently the Public Works Research Institute), the Advanced Construction Technology Center and 22 private companies. Technology development "Construction sludge improved soil durability". In other words, a total of 3 days, 2 days at 40 ° C oven drying and 1 day at 20 ° C water immersion, is one cycle. After drying each cycle, the condition of the specimen is observed and photographed after water immersion. A compression test was conducted to examine changes in uniaxial compressive strength as the number of cycles increased. As the situation observation, the soundness of the specimen was evaluated based on the soundness rank shown in Table 3.

  In this experiment, “fibrous solidified soil” and “solidified soil” as comparative products, “PS solidified soil”, “PS solidified soil (without chemicals)” and “fibrous solidified” as products of the present invention. Three types of specimens of “treated soil (without chemicals)” were prepared and subjected to repeated wet and dry experiments. By creating these three types of specimens, the following points can be confirmed.

1. From the viewpoint of durability against repeated wet and dry cycles, whether PS can be a substitute for waste paper crushed material (results of “fibrous solidified soil” as a comparison target and “PS solidified soil” of the present invention) The effect of the invention can be verified by comparing
2. Whether the chemical contributes to the strength characteristics of the treated soil and the durability against repeated wet and dry (for comparison and comparison of “PS solidified soil” and “PS solidified soil (no chemical)” of the present invention) It can be verified by comparing the results of “Fiber solidified soil” of the present invention and “Fiber solidified soil (without chemicals)” of the present invention).

  In conducting the experiment, 12 specimens were prepared for each specimen. Since three specimens were used for the uniaxial compression test at the end of a predetermined cycle (0, 2, 6, 10 cycles), as a method for evaluating the soundness, 9 specimens were used for 3 cycles. Up to 6 cycles, 6 specimens were observed, and from 7 to 10 cycles, 3 specimens were observed, respectively, and A to H (evaluation in Table 3) were quantified into 8 stages to obtain an average rank. .

4.1 Test results Figures 4 and 5 show the relationship between the number of cycles and the uniaxial compressive strength. FIG. 4 shows the result when the initial water content is 105%, and FIG. 5 shows the result when the initial water content is 150%. In the figure, the ▲ and ● marks indicate the results of the comparison solidified soil and fiber solidified soil, and the ○, △, and □ marks indicate the PS solidified soil and PS solidified soil (no chemicals) according to the present invention. ), The result of the fiber-solidified soil (without chemicals).

  As described above, in conducting the wet and dry repeated experiment, 12 specimens were first prepared for all specimens. The numerical value (fraction) shown in the figure indicates (number of specimens subjected to the uniaxial compression test) / (number of specimens existing when performing the uniaxial compression test). That is, 3/12 means that there are 12 specimens at 0 cycle, 3 of them were subjected to a uniaxial compression test, and the average value was plotted in the figure. That is, in the case of the fiber-solidified soil, three specimens are always used for the uniaxial compression test, and the denominator value is always reduced by three. This indicates that the specimens kept their shape without collapsing through 10 cycles, and that three specimens could always be subjected to the uniaxial compression test.

  ● Comparing the results of the mark and the result of the mark ○, the strength of the fiber-solidified soil is higher than that of the PS-solidified soil throughout the number of cycles, but the PS-solidified soil is also subjected to a uniaxial compression test. It is always possible to provide three specimens, and the strength value does not decrease with the increase in the number of cycles, and after the end of 10 cycles, the value is higher than the initial strength, and there is almost no deterioration. I understand. Therefore, from the viewpoint of durability against repeated wet and dry, it can be determined that PS can be a substitute for waste paper crushed material. Note that the strength of the PS solidified soil after the 10th cycle increased from the initial strength is considered to be due to the strength of the soil being not affected by repeated wet and dry processes and the hydration reaction of the cement.

  Next, when comparing “○ and △” and “● and □”, the treated soil (△ and □) that does not use chemicals as a whole is treated with chemicals (○ and □). ● It can be seen that the strength is higher than This is thought to be because the auxiliary agent used in this experiment (Bonteran-L) has a pH of about 3 and exhibits strong acidity, so that the auxiliary agent prevents the hydration reaction of the cement when the auxiliary agent is added. Therefore, it is desirable not to add chemicals in terms of the strength of the treated soil. In addition, it was confirmed that the treated soil to which no chemical was added was highly resistant to repeated wet and dry cycles, and the drug hardly contributed to the durability to repeated dry and wet conditions.

  6 and 7 show the relationship between the soundness rank and the number of cycles. As shown in this figure, the solidified soil becomes less healthy as the number of cycles increases, but the health of other treated soils is always A rank regardless of the number of cycles, and deteriorates even after repeated drying and wetting. It can be seen that there is almost no change in appearance. That is, the reason why the fiber solidified soil and PS solidified soil exhibit high durability against repeated wet and dry is that the fibrous material is present in the treated soil, and the chemicals do not contribute to the durability. Rather, it is a factor that slightly decreases the strength.

  Considering the above results, it is better to treat mud with only fibrous materials such as PS and / or waste paper crushed material without adding chemicals at sites where there is sufficient temporary storage / curing period. It can be said that it is excellent in cost.

5). Strength characteristics of PS solidified soil From the results in the previous section, it was confirmed that PS can be a substitute for waste paper crushed material from the viewpoint of durability against repeated wet and dry conditions. Then, the optimum PS addition amount is examined from the viewpoint of the strength characteristics of the treated soil.

Here, first, a target value (reference value) that the treated soil should satisfy is set, and the optimum PS addition amount is quantitatively evaluated. Each target value and the reason for setting are described below.
5.1 Target strength qu
The following points can be cited as conditions for setting the target strength.
1) It must be strong enough to satisfy the trafficability required for running construction machinery.
2) The required strength when containing hazardous substances in place to prevent leakage.
3) The strength is required for reuse in the roadbed, road embankment, and the back of structures.

The strength necessary to achieve the above-mentioned target needs to satisfy the following uniaxial compressive strength.
1) qu = 50-100kN / m ^2
2) qu = 200kN / m 2 or more
3) qu = 100-300kN / m ²

The quality classification when using the treated soil of construction sludge as a soil material is based on the corn index qc in principle, and it is desirable to ensure that qc = 800 kN / m ² or more. In addition, since the relationship between the cone index qc and uniaxial compressive strength qu of construction sludge solidified soil is qc = 5 to 15 qu, the uniaxial compressive strength requires a strength of qu = 160kN / m ² or more from the safety side. Will be.

However, when re-digging is necessary for lifeline burial or the like, care must be taken to prevent re-digging from becoming too strong due to excessive strength. The strength that can be easily re-excavated with a hydraulic excavator is 500 to 1000 kN / m ^{2 in} terms of uniaxial compressive strength. Therefore, the uniaxial compressive strength of the treated soil needs to be kept within this range. Therefore, the target strength of PS solidification workers proposed in this study is a comprehensive judgment to ^{qu = 200kN / m 2 ~300kN /} m 2 approximately.

5.2 Target deformation factor E ₅₀
The deformation coefficient E ₅₀ is defined by the slope of a straight line connecting the point qu / 2 half the peak stress qu and the origin in the stress-strain curve in the uniaxial compressive strength test, and the larger this value, the harder the material is. When the treated soil is reused as embankment or backfill soil, it is necessary to improve the familiarity with the surrounding ground without showing extreme discontinuity with the original ground. Solidified soil shows strength characteristics like concrete and rock, so there is a difference in rigidity between the surrounding ground and existing embankment and the new embankment with solidified soil. When the foundation ground is subjected to large deformations, there is a concern that cracks due to local deformation concentration occur in highly rigid parts. Therefore, the deformation coefficient of PS solidified soil that is recycled by the method of the present invention needs to be close to the deformation coefficient of normal soil.

FIG. 8 shows the deformation coefficient when the solidified soil, the fiber solidified soil and the normal soil are solidified. Normal soil refers to masa soil, loam and mountain sand, and the deformation coefficient of normal soil shown in the figure is a value quoted from publicly known literature. Although the deformation coefficient of the fiber-solidified soil and the normal soil has the same value, the deformation coefficient of the solidified soil shows a value 3 to 5 times the deformation coefficient of the fiber-solidified soil. This indicates that the solidified soil has hard and brittle concrete properties. The deformation coefficient of the PS solidified soil proposed in the present invention becomes a target value E ₅₀ = 20 MN / m ² or less if the target strength is qu = 200 to 300 kN / m ² .

5.3 Target fracture strain ε _f
According to the inventor's knowledge based on a separate experiment, the solidified soil after the triaxial compression test shows a clear shear surface and local stress concentration, whereas the fibrous solidified soil is a barrel. Mold deformation occurs and stress concentrations are distributed throughout the fiber. This means that in the fiber-solidified soil, the fibrous material enters in a complex manner between the soil particles, and as a result, the bond strength between the soil particles is extremely high, suppressing the occurrence of cracks and leading to fracture. Shows that it can withstand large deformations. Similarly, the reason why the fiber-solidified soil exhibits high durability against repeated drying and wetting is presumed that the fiber strengthens the bond between the soil particles and suppresses the generation of cracks. It was evaluated quantitatively from the value of fracture strain. FIG. 9 shows the relationship between the uniaxial compressive strength and the fracture strain, and it can be seen that the boundary line when the bond strength between the soil particles of the fiber-solidified soil and the solidified soil is evaluated by the fracture strain is about 5%. . Therefore, the target fracture strain ε _f is 5% here.

By the way, in the previous section, it was confirmed that the absence of the chemical was superior in terms of strength, and thus the treated soil was prepared without adding the chemical. That is, the initial for the water content of 105% of the mud by changing the PS amount to ^{50kg / m 3, 70kg / m} 3 and 90 kg / m ^3, also with respect to the initial water content of 150% of the mud 65 kg / PS solidified soil (without chemicals) was prepared by changing to m ³ , 85 kg / m ³ and 105 kg / m ³ , and a uniaxial compression test was performed.

  10 and 11 show the relationship between the PS addition amount, uniaxial compressive strength, fracture strain, and deformation coefficient. 10 and 11 show the results when the initial moisture content is 105% and 150%, respectively. For reference, the values of solidified soil, fibrous solidified soil, and fibrous solidified soil (without chemicals) are also shown.

From this figure, the uniaxial compressive strength was within the range of the target strength for any PS addition amount, but the target for any PS addition amount for fracture strain and deformation coefficient. The value has not been reached. In other words, although PS solidified soil (without chemicals) has high durability against repeated wet and dry cycles, it may be evaluated that the strength characteristics are not necessarily sufficient depending on the application.
Here, the present inventor obtained a new idea of supplementing the shortage of fracture strain and deformation coefficient with waste paper crushed material, created PS fiber solidified soil (no chemical), and conducted a -axial compression test. .
The experimental results will be described in the next section.

6). Strength characteristics of PS solidified soil Here, PS is fixed at 70 kg / m ³ for mud with an initial moisture content of 105%, and PS is added for mud with an initial moisture content of 150%. Was fixed to 85 kg / m ³ , PS fiber solidified soil (without chemicals) was prepared by varying the amount of waste paper crushed material added to each mud, and a uniaxial compression test was performed. 12 and 13 show the relationship between the added amount of waste paper crushed material, uniaxial compressive strength, fracture strain, and deformation coefficient. 12 and 13 show the results when the initial moisture content is 105% and 150%, respectively. For reference, the values of solidified soil, fibrous solidified soil, and fibrous solidified soil (without chemicals) are also shown.

The uniaxial compressive strength gradually increases with the amount of used paper added. Although there is variation in data, the fracture strain generally tends to increase with an increase in the amount of used paper up to about 30 kg / m ³ , and then tends to show a constant value thereafter. On the contrary, the deformation coefficient tends to decrease as the amount of used paper increases up to about 30 kg / m ³ , and then tends to be almost constant after that. Further, when the amount of used paper added is about 30 kg / m ³ for any water content, all of the target strength, target fracture strain and target deformation coefficient are satisfied. That is, when comprehensively judging the above results, the durability if used paper to about 30kg / m ³ (if Shimese range obtained effective 20 to 50 kg / m ³⁾ added, PS fibrous solidification soil for wet and dry repeatedly It can be judged that it has high properties and is excellent in strength and can sufficiently withstand use as a banking material.

  By the way, the cost when processing high moisture content mud with the fiber solidification earthwork method is estimated considering the material cost of the waste paper mixture to be mixed, the material cost of the chemical, the material cost of the cement, the loss of heavy machinery, etc. The If the moisture content is 100%, the construction cost of the fiber solidification earthwork method of the present invention that does not use chemicals will be reduced by about 65% compared to the construction cost of the fiber solidification earthwork method using conventional chemicals. Become. Furthermore, PS is provided free of charge, and if this PS is used, the amount of waste paper crushed material can be reduced by half. The cost can be significantly reduced by about 75%.

  Furthermore, the merit of using PS is not only reduction of construction cost. In other words, if PS can be applied to the fiber-solidifying earth method, the processing cost for processing PS at the final disposal site becomes unnecessary, leading to an improvement in the recycling rate of PS, and an extremely large industrial advantage can be obtained.

7). Conclusion The present invention aims to improve the recycling rate of paper sludge (PS), which is waste generated from recycled paper mills, and to stabilize the construction cost and reduce the cost of the fiber solidification earth method already proposed by the inventor. In addition, it was confirmed that a sufficient effect can be obtained by using PS for the fiber solidification processing earth method.

From the above, the results of the above-described experiment described in the embodiment and the effects of the present invention derived therefrom are summarized as follows.
1) PS was mixed with high-moisture specific mud instead of crushed waste paper, and treated soil was created. As a result of repeated wet and dry experiments, the treated soil showed high durability against dry and wet cycles. In other words, from the viewpoint of durability against repeated wet and dry cycles, PS can be used as a substitute for waste paper crushed material, and it has been confirmed that sufficient effects can be obtained.

 2) As a result of making two types of treatment soils with and without chemicals added, and the results of repeated wet and dry experiments, the treated soil without chemicals showed higher strength. In addition, both of the durability against repeated wet and dry cycles are high, and the chemicals are not only involved in the durability, but also hinder the hydration reaction of the cement. Therefore, it is better in terms of strength and cost to treat mud with only fiber materials such as PS or crushed paper without adding chemicals at sites where temporary storage and curing periods are sufficient. Was confirmed.

3) However, it can be judged that there is still room for soil that has been regenerated only by PS, that is, PS solidified soil, in terms of strength characteristics. It added to create the PS fibrous solidification soil, the uniaxial compression test result of examining the strength characteristic of working to treated soil and approximately half 20 to 50 kg / m ³ degree about used paper crushing of the conventional used paper amount It was confirmed that when the materials were mixed, earth and sand having high durability against repeated wet and dry cycles and excellent strength characteristics could be produced. As a result, it was confirmed that the construction cost could be reduced by about 75%.

It is a figure which shows the component mass ratio of PS used for the experiment demonstrated in embodiment of this invention. It is a photograph which shows PS used in the experiment explained by the embodiment of the present invention. It is a figure which shows the preparation flow of the specimen used for the experiment demonstrated by embodiment of this invention. It is a figure which shows the relationship between the cycle number of each test body obtained by the experiment demonstrated by embodiment of this invention, and uniaxial compressive strength. It is a figure which shows the relationship between the cycle number of each test body obtained by the experiment demonstrated by embodiment of this invention, and uniaxial compressive strength. It is a table | surface figure which shows the relationship between the soundness rank of each test body and the cycle number in the experiment demonstrated by embodiment of this invention. It is a table | surface figure which shows the relationship between the soundness rank of each test body and the cycle number in the experiment demonstrated by embodiment of this invention. It is a figure which shows the deformation coefficient at the time of solidifying treatment of solidification soil, fibrous solidification soil, and normal soil. It is a figure which shows the relationship between uniaxial compressive strength and fracture strain. It is a figure which shows the relationship between PS addition amount in the experiment demonstrated by embodiment of this invention, uniaxial compressive strength, fracture strain, and a deformation coefficient. It is a figure which shows the relationship between PS addition amount in the experiment demonstrated by embodiment of this invention, uniaxial compressive strength, fracture strain, and a deformation coefficient. It is a figure which shows the relationship between the addition amount of used paper crushed material in the experiment demonstrated by embodiment of this invention, uniaxial compressive strength, fracture strain, and a deformation coefficient. It is a figure which shows the relationship between the addition amount of used paper crushed material in the experiment demonstrated by embodiment of this invention, uniaxial compressive strength, fracture strain, and a deformation coefficient.

Claims (9)

Improved soil made by adding and mixing paper sludge and cement-based solidified material to high water content mud. An improved soil made by adding and mixing paper sludge, waste paper crushed material, and cement-based solidified material with high water content mud. The improved soil according to claim 1 or 2, wherein the added amount of the paper sludge is 50 to 105 kg / m ³ in a ratio to the high water content mud. The improved soil according to claim 2, wherein the amount of the crushed waste paper is 10 to 65 kg / m ³ in a ratio to the high water content mud soil. The paper sludge is a powder obtained by removing water from a mixture of water and solid sludge discharged in the recycling process of waste paper, and then pulverizing the paper sludge. 4. Improved soil according to 4. Add paper sludge to high water content mud and mix without adding polymer improver and auxiliaries, then add cement solidifier and mix, then cure until desired strength is developed A method for producing improved soil, characterized in that the method is carried out. Add paper sludge and 10 to 65kg / m ³ waste paper crushed material to high water content mud and mix without adding polymer improver and auxiliary agent, then solidify cement A method for producing improved soil, comprising adding and mixing materials, followed by curing until a desired strength is exhibited. It is an improved substance that is added to high water content mud to improve the strength characteristics and deterioration durability of the mud, and removes water from the mixture of water and solid sludge discharged in the recycling process of waste paper and pulverizes it. Paper sludge characterized by being a powder. At least one fibrous material selected from the group consisting of crushed waste paper and paper sludge and cement-based solidified material are added to the high water content mud and mixed without adding polymer-based improving materials and auxiliary agents. Improved soil.