JP2007016395A - Manufacturing method for bank construction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a bank construction material for a reservoir bank, river bank, etc. , which method uses construction sludge that is discharged when fine aggregate for concrete are refined from weathered granites and pit sand. <P>SOLUTION: According to the manufacturing method for the bank construction material, construction surplus soil containing clay and silt is dewatered with pressure into a caked state to produce pressed soil, which is mixed with pit sand or clay. In the mixing process, a mixing ratio between the pressed soil and the pit sand is adjusted to adjust the viscosity of the mixed soil, and the water content is also adjusted to adjust the water content ratio of the mixed soil. The pressed soil, which is construction surplus soil produced in a process of extracting and fining pit sand or decomposed granites, is obtained by depositing and dewatered with pressure the construction surplus soil produced in a process of refining fine aggregates for concrete from weathered granites. The above water content adjustment is carried out by adjusting the dewatered volume upon dehydration of the construction surplus soil. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for producing embankment materials such as reservoirs and river dikes using construction sludge discharged when refining concrete aggregates from weathered granite or mountain sand.

Mountain sand (weathered granite) is often used in some regions as aggregate for concrete (fine aggregate). Mountain sand, which is weathered granite, varies depending on the degree of weathering, but contains approximately 20% of silt and clay. This has an adverse effect on the quality of concrete. There is.
Therefore, in the sand production factory of mountain sand, sand is removed to remove this silt and clay, and the waste water is solidified using a filter press and disposed of. However, if this pressed soil is treated in the factory, it is considered that there is no legal problem. However, if it is taken out of the factory, it will be handled as industrial waste, which requires a lot of processing costs and is a source of trouble for sand mills.
On the other hand, when rehabilitating ponds, it is becoming difficult to collect on-site materials due to environmental problems.

On the other hand, as a construction method when using only soil materials for embankment construction,
(1) Uniform mold method (uniform material occupies 80% or more),
(2) Zone type construction method (material consists of water-impervious material and semi-permeable material or permeable material)
There is. For the embankment material, the material (mountain area) as close as possible to the economy is judged by soil investigation and testing to determine the suitability, and the embankment material is built by the method (1) or (2) above.

The embankment material must have the following properties (a) to (d).
(A) A particle size distribution giving a high density, a high shear strength, and stability.
(B) The water permeability should be within the allowable range of the body for the maximum head.
(C) The shrinkage ratio is small, suitable plasticity, and does not become soft mud when saturated with water.
(D) Mineral components are insoluble without containing organic substances.
Table 1 below shows suitability as a material having the above properties.

  Selection of embankment materials is considered to select the most economical (near) and safe (high shear strength) material with reference to Table 1, but if natural materials are used economically, Table 1 The more suitable the material, the harder it is to secure in quality (2 to 3 times the planned quantity), and it is often a highly weathered clay or silt (CH, MH) material depending on the nearby soil material. It was a material with a low degree of appropriateness.

  Such materials with low suitability are impermeable soils but have low shear strength. Compared with other materials (high suitability), the slope of the levee tends to have a gentle slope and the amount of embankment tends to increase. It becomes. In embankment construction, depending on the type, weight, and number of rolling operations of the compaction machine, kneading may occur, causing problems of softening of the embankment and trafficability of the construction machine (the ability of the soil to withstand the running of the machine). . In addition, the water permeability, which is important for preventing leakage as a dike, depends on the construction machine, but the layer boundary becomes a smooth surface when constructed with a roller that makes the finished surface after compaction particularly smooth. It is difficult to ensure the prescribed water permeability. Therefore, it is necessary to improve the familiarity of the layer boundary by scratching the finished surface (depth 1 to 3 cm) with a backhoe etc. for each layer, which is a problem in terms of time and work (requires training for operations). there were.

  In addition, the number of days waiting for work after rainfall on the embankment is short in summer when the temperature is high and easy to dry, and long in winter. This is because the strength changes remarkably as the water content increases or decreases. Compared to sandy soil, generally 3 to 5 times the number of work suspension days are required. In this way, earthworks made of materials that are significantly affected by rainfall and snowfall required countermeasures against rainfall and snowfall.

  In addition, the embankment material is mostly collected from nearby forests, and it is necessary to secure an amount of soil that is 2 to 3 times the amount of embankment and a suitable earth catch. In that case, compensation for standing trees will occur, and felled wood from standing trees must be treated as industrial waste. In addition, construction costs such as the construction of hypothetical roads to the pit and the problems of post-processing after collecting the embankment materials were required. Recently, such destruction of nature has been perceived as a very serious problem as part of environmental and resource problems.

  In the present invention, about 20% of silt / clay sludge produced when refining concrete fine aggregate from weathered granite or mountain sand is discharged with press soil (industrial waste) and mountain sand. By mixing and transporting with a dump truck while changing the mixing ratio, materials necessary for levee materials (impermeable material, semi-permeable material, permeable material), providing materials with higher suitability, and nearby It is intended to provide a method for producing embankment materials that contributes to environmental and resource problems by preventing natural destruction of forests.

  The manufacturing method of the embankment material of the present invention for solving the above-mentioned problem is as follows. First, a press soil obtained by pressurizing and dehydrating a construction residual soil containing clay and silt to form a cake, and solid sand or clay. And mixing the clay in the mixed soil by adjusting the mixing ratio of the pressed soil and the mountain sand, and adjusting the water content ratio by adjusting the water content.

  Second, it is characterized by mixing pressed soil, which is construction residual soil generated in the process of collecting and refining mountain sand or masa soil, and mountain sand or masa soil refined through the sampling and refining process.

  Thirdly, the press soil is characterized by sedimentation and pressure dewatering of construction residual soil generated in the process of refining fine aggregate for concrete from weathered granite.

  Fourthly, it is characterized in that the moisture adjustment is performed by adjusting the amount of dewatering during the pressure dewatering of the construction soil.

  The embankment material of the present invention configured as described above is a uniform, coarse and fine-grained material that is appropriately mixed by mixing two types of soil materials with a sand mixer or the like according to the needs of the ordering side. It becomes a new embankment material with good particle size distribution and high suitability. The embankment material has good workability, high shear strength, and is stocked as mixed improved soil that can clear the specified water permeability after construction. And it is supplied to the desired new embankment embankment work by dump truck etc. and can match the needs of embankment material in the embankment construction, so the construction sludge in the refining process of concrete fine aggregate is not just industrial waste but effective Can be reused as embankment material.

  Also, by mixing mountain sand, particle size adjustment (mixing ratio) and water content ratio adjustment (press soil) can be optimized, and the water permeability (water-impervious, semi-permeable, water-permeable material) and strength as a dike structure are sufficient It can be supplied as a satisfactory mixed material with a high degree of abstraction. Therefore, the third type of application standards (see Tables 2 and 3 below) of the guidelines of the Ministry of Land, Infrastructure, Transport and Tourism are cleared, the backfill of the work, the road bed and road body embankment, the backfill of the structure, the river embankment It can also be used for land development.

Hereinafter, a method for refining a fine aggregate for concrete and a method for producing a levee material will be sequentially described with reference to the drawings.
(1) Method of refining fine aggregate for concrete As shown in FIG. 1, the raw stone (weathered granite) A is divided into the one containing silt and the one not containing silt, and put into buckets 1 and 1 ', respectively. The raw stone A is separated by the screen 2 and the bar screen 2 '. And the thing which does not contain a silt part or few is selected with a bar screen 2 'and a thing with a particle size of 20 mm or less, and the mountain sand B is obtained. On the other hand, the one with a lot of silt is separated by the screen 2 and then crushed by the rod mill 3. After the separation by the screen 4 again, the powder is removed by the classifier 5, the water is removed by the dewatering screen 6, and the sand is removed. Sand is removed on the screen 7 to obtain processed sand C which is fine aggregate for concrete. Moreover, the waste soil containing the silt content removed in the classifier 5 is precipitated in the settling tank 8 and pressed by the high pressure dewatering press 9 to obtain a pressed soil D.

  Here, the pressed soil will be described. Usually, sandstone mills use weathered granite as raw stone when refining fine aggregate for concrete. This weathered granite contains about 20% silt (debris with a particle size intermediate between sand and clay) and clay, although it varies depending on the production area and the degree of weathering. What is commonly called mud contains silt and clay.

This silt and clay content adversely affects the concrete quality, such as decreasing the strength of concrete, increasing the unit water volume, and generating cracks. Therefore, its content (lost in the washing test) is included in the Ready Mixed Concrete (JISA 5308) appendix. Defined as 3% or less. For this reason, sand mills try to ensure the quality required for fine aggregates for concrete by removing the silt and clay content by washing the grain-adjusted mountain sand with water. This sand-washed sewage solidified with a high-pressure filter press is pressed soil (dehydrated cake), and the water content is approximately 30%.
(2) Manufacturing method of embankment material As described above, the press soil D from which the construction sludge of about 20% silt / clay produced when refining the fine aggregate for concrete is discharged by the high-pressure filter press machine 9 is solid liquid The separated particle size is uniform. And since the moisture content can be adjusted by the moisture adjusting device installed in the high-pressure filter press machine 9, it is used as a soil material in the “Generation and Use Standards (draft), Construction Sludge Recycling Technical Standards (draft)” by the Ministry of Land, Infrastructure, Transport and Tourism. Appropriate blending ratio and moisture content can be set to match the quality classification, quality standard value and each soil condition as a dike.

  The press soil D discharged from the high-pressure filter press 9 is stored in a predetermined stock yard (not shown), and sandy components such as mountain sand B are also stored in another stock yard (not shown). As shown in FIG. 2, each of them is distributed by a backhoe or the like to a press soil hopper 21 and a mountain sand hopper 25 that also serve as a screen and temporarily stored. The hopper 25 also has a function of discharging smoothly while loosening the press soil, which is also used as a loosening machine.

  The press soil D and mountain sand B are uniformly discharged from the hoppers 21 and 25 based on the blending ratio. A belt feeder machine (transportation supply device) 22 is installed on the discharge side of the press soil hopper 21, and a belt feeder machine (transportation supply device) 26 is also installed on the discharge side of the mountain sand hopper 25. By controlling the number of rotations of the belt feeders 22 and 26 with the inverter by the system control panel 30, the press soil D and the mountain sand B corresponding to the needs (mixing ratio) from the ordering side are discharged.

  The belt feeder 22 that receives the press soil D is provided with a load cell (load sensor) 23 for quantitatively controlling the press soil D, and a loader (feed device) 24 for discharging the cake (press soil D). Is installed. The load speed of the loader 24 is also controlled by the system control panel 30.

  The press soil D discharged by the belt feeder 22 and the cake discharge loader 24 and the mountain sand B discharged by the belt feeder 26 are conveyed by a belt conveyor (conveying device) 27 and mixed by a mixer (mixer) 28. Is done. And the mixed soil (embankment material) E is conveyed by the belt conveyor 29, and is stored in predetermined places, such as a stockyard.

  The mixed soil E, which is a mixture of two types of soil by the above method, is a uniform material with a good particle size distribution in which coarse and fine particles are appropriately mixed, has good workability, high shear strength, and is designated. It is a mixed improved soil whose water permeability can be cleared after construction. The stocked mixed soil (embankment material) E is supplied to a desired new embankment embankment work by a dump truck or the like and matched with the needs of the embankment material in the embankment construction. Therefore, the construction sludge in the process of refining concrete fine aggregate can be reused as an effective resource, not industrial waste.

  Moreover, even when these two types of mixing determine the mixing ratio and mix in a uniform particle size distribution, it may be difficult to meet the needs from the ordering side depending on the water content ratio of the material after mixing. Therefore, the shear strength (adhesive strength, internal friction angle), water permeability (water permeability coefficient), and compaction degree (water shielding material—more than 95% of the maximum dry density, other materials—90% of the maximum dry density) after compaction The numerical value may vary depending on the water content of the mixed soil E, and the prescribed order may not be satisfied. Therefore, it is necessary to clear various restrictions and regulations in the process of adjusting the water content of the press soil D by the high-pressure filter press 9 and in the process in which the two materials are fed into the mixer 28 at a set mixing ratio. This mixed soil E is a new embankment material that has fully and reliably cleared the standard value of construction generated soil that is more than the third type (see Tables 2 and 3 above) of the usage standards outlined in the Ministry of Land, Infrastructure, Transport and Tourism guidelines. .

The construction sludge discharged for refining the concrete fine aggregate (processed sand C) by the high-pressure filter press 9 is designated as dewatered press soil D having a cone index of 400 kN / m ² or more. In that case, it can be used for backfilling of works, road bed / road body embankment, backfilling of structures, river embankments, land preparation, etc. in order to clear the third type of application standard of the guidelines of the Ministry of Land, Infrastructure, Transport and Tourism. is there. By mixing the mountain sand B, particle size adjustment (mixing ratio) and water content ratio adjustment (press soil) can be optimally performed, and the water permeability (water-impervious, semi-permeable, water-permeable material) and strength as a bank structure are sufficient. Can be supplied as mixed soil E having a high degree of abstraction. The mixed soil E is transported from the production plant to a new embankment by a dump truck as needed. It will be able to meet the needs of construction measures such as rainfall measures and the relationship between embankment and hydraulic conductivity.

  Mixing ratio and moisture content of pressed soil D and mountain sand B discharged by high-pressure filter press 9 for construction sludge discharged when refining concrete aggregate (processed sand C) from weathered granite (raw stone A) While changing the ratio, the shear strength, compaction degree, construction moisture content, and water permeability coefficient of the mixed soil E shown in the specially specified specifications are sufficiently satisfied as a fill material.

  The target is a material with a high degree of suitability as an embankment material, and a mixture ratio in which a coarse particle size (mountain sand B) and a fine particle size (press soil D) are mixed appropriately is obtained, and a uniform particle size distribution is obtained. Before putting the press soil D and the mountain sand B into each of the hoppers 22 and 25, the natural moisture content of each material is measured, and the mixed soil is manufactured with the mixing ratio set by each process. After production, measure the natural moisture content and confirm that it is within the specified construction moisture content range.

  If the natural moisture content is out of the range, it is adjusted by the process of adjusting the moisture content of the press soil D with the high-pressure filter press 9 and the natural moisture content is measured after the mixed soil E is manufactured again by each process, and the designated construction water content Repeat until the ratio is within the range. If the natural water content of the mixed soil E is within the range of the specified water content after the work of each process is performed, the mixed soil E is clearly indicated in the special specification, the shear strength (C: adhesive strength, Φ : Internal friction angle), compaction degree (maximum dry density ρdmax 95% to 90% or more), construction water content (optimum water content to wet side), water permeability (water-impervious material, semi-water-permeable material, water-permeable material) If these can be cleared, the mixed soil E is produced in each process and transported to a new embankment by a dump truck or the like as needed.

  When embankment is made of nearby natural materials, there is almost no highly suitable material with moderately mixed coarse and fine particles, and it becomes a fine-grained material (silt, clay) of strongly weathered soil with an emphasis on water shielding. There is a tendency. In this fine-grained material, it is particularly important to take measures against rainfall as compared with a material having a high degree of suitability in which a coarse particle size and a fine particle size are appropriately mixed. If the embankment is carefully rolled using fine-grained material and the surface drainage is good, the increase in moisture content due to rain is only observed on the surface layer within 10 cm, but if there is rain in the unrolled state Further, the water content ratio increases from 30 to 50 cm from the surface, the construction becomes difficult, and the construction start after the rain is delayed for several days.

  In addition, when the surface after raining is not dry, if it is constructed, it will be twisted and softened, making it difficult. Therefore, after raining, once the construction machine's trafficability (the ability of the soil to withstand the running of the machine) can be secured, the construction is restarted, or the embankment is stripped about 10 cm from the surface where the influence is observed by the rain. Either take off or resume construction. In that case, the removed soil is treated as a residual soil.

  Even if there is no rain, the soil has a high moisture content, and if the compaction energy of the construction machine is increased, the surface after rainfall will dry out even if the energy is small and the number of rolling is increased. There is a possibility of twisting in the same way as when not, and if twisted, leaving it for several days will restore strength and reduce the moisture content, greatly improving machine trafficability can do.

  Thus, it is necessary to take measures against rainfall, but the energy of the construction machine and the number of rolling times are also important points. Similarly, the soil collection site (fine-grained soil) needs to be protected against rain, and a shoulder ditch (water stop) is placed at the site to prevent inflow of surface water. At the same time, it is necessary to provide a drainage ditch to reduce the groundwater.

  In the mixed soil produced this time, by mixing coarse and fine-grained soils in a highly suitable mixing ratio, if the specified compaction is applied to this material, an increase in the moisture content due to rainfall is recognized on the surface layer. However, compared to fine-grained soil, the start of work is quicker and the work can be performed even when the surface is slightly moistened, so that sufficient trafficability of the construction machine can be secured. Moreover, even if the energy of the construction machine is increased and the number of rolling operations is increased, the twist does not occur and the strength is increased and the water impermeability becomes stronger as it is compacted. Therefore, it is possible to obtain a mixed soil that is very easy to construct and fast.

  The method for producing a levee material according to the present invention is not limited to construction sludge in the refining process of fine aggregate for concrete, but is also an effective embankment material or other construction material for industrial waste that has been disposed of as industrial waste in the past. Can be reused as

It is a flowchart which shows the refinement | purification method of the fine aggregate for concrete. It is a flowchart which shows the manufacturing method of embankment materials.

Explanation of symbols

1 Bucket 1 'Bucket 2 Screen (sorting device)
2 'Bar screen (sorting device)
3 Rod mill (pulverizer)
4 screen (sorting device)
5 Classifier (sorting device)
8 Sedimentation tank 9 Press 21 Hopper 22 Belt feeder
23 Load cell (load sensor)
24 Loader
25 Hopper 26 Belt feeder
27 Belt conveyor (transport device)
28 Mixer
29 Belt conveyor
30 System control panel A rough (weathered granite)
B Mountain sand C Processed sand (fine aggregate for concrete)
D Press soil E Mixed soil

Claims (4)

  Pressed dewatered construction soil containing clay and silt is mixed into cake and solidified by mixing with sand and clay, and mixing is performed by adjusting the mixing ratio of pressed soil and mountain sand. A method for producing embankment materials that adjusts the moisture content by adjusting the soil clay and moisture.   The method for producing a levee material according to claim 1, wherein the pressed soil, which is construction residual soil generated in the step of collecting and refining mountain sand or masa soil, and the mountain sand or masa soil refined through the extraction and refining step are mixed.   3. The method of producing a levee according to claim 1 or 2, wherein the pressed soil is obtained by precipitating and dewatering the construction residual soil generated in the step of refining concrete fine aggregate from weathered granite.   4. The method for producing a bank embankment according to claim 1, wherein the moisture adjustment is performed by adjusting the amount of dewatering during the pressure dewatering of the construction residual soil.

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