JP3438499B2 - Solidified material for fluidized backfill and fluidized treated soil using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is suitable for use in a fluidized backfilling method for excavating a sewage pipe, a gas pipe, an electric wiring, a telephone line or the like in an urban street in the Kanto region or for excavating a repair work. The present invention relates to a solidifying material for fluidized backfilling and a fluidized treated soil using the solidified material.

[0002]

2. Description of the Related Art Conventionally, the backfilling of excavation points caused by the burial and repair work of water and sewer pipes, gas pipes, electric wiring, telephone lines, etc. has been carried out by using a good quality soil such as mountain sand with a rammer. It is done by the method of pressing. However, with non-viscous materials such as sand and sand, it is difficult to fill complicated pipes, and insufficient filling may cause road collapse. In addition, in particular, not only the cost burden becomes large when procuring and carrying in mountain sand, etc. into the urban area and unloading and discarding excavated soil from the urban area, but also at the point where the mountain sand is collected and the excavated soil is discarded. Since there are problems from the viewpoint of environmental protection, it is necessary to review the conventional construction method. One method of solving the problems of this conventional method is to use the excavated soil itself as a backfill material, and the excavated soil was mixed with water and a solidifying material to give fluidity and solidification. A fluidization backfilling method is being studied in which a compaction-free slurry is prepared and used as a backfill material. For the treated soil slurry used for backfilling,
Fluidity that can be filled in the lower part of buried pipes and gaps between congested pipes, quick hardening and human excavation that enables restoration work such as compaction of sand or crushed stone on the backfilled treated soil in the shortest possible time after placing In general, the fluidity at the time of driving is 150-200 mm by the Kodan 305 cylinder method (Road Standards), and the uniaxial compressive strength is 0.1-hour within 1 hour after driving. 0.3 kgf / cm ² , 2 after placing
Values of 3-8 kgf / cm ² are required after 8 days.

In such a fluidized backfilling method, the use of a solidifying material containing calcium aluminate, a calcium sulphoaluminate compound, hemihydrate gypsum, etc. as a main component and various additives has been studied. For example, JP-A-1-299913, JP-A-5-17771, JP-A-7-26542, JP-A-7-292356, JP-A-6-298553 and JP-A-8-109377.
It is disclosed in each publication of the issue.

On the other hand, the fluidization backfilling method is being studied mainly in urban areas, and particularly in urban areas in the Kanto region including the Tokyo metropolitan area. The main excavated soil in this area is volcanic ash cohesive soil called Kanto loam, but as a solidifying material for this volcanic ash cohesive soil, the effect of lime and gypsum has been known for a long time. Also, for example, Japanese Patent No. 2503
771 specification etc. are disclosed.

[0005]

However, the solidifying material composed of calcium aluminate or calcium sulphoaluminate is expensive, and the conventional solidifying material for lime-based volcanic ash cohesive soil is the above-mentioned fluidized material. Not only is it impossible to ensure the necessary fluidity for special construction such as the backfilling method, especially the effect on general coarse-grained soil and fine-grained soil other than volcanic ash cohesive soil. It has the drawback of being small. The object of the present invention can be particularly suitably used for the fluidized backfilling method of volcanic ash cohesive soil, but is applicable to other than volcanic ash cohesive soil, that is, volcanic ash cohesive soil is the main component of soil. (EN) It is possible to provide a novel solidified material which can be suitably used for a fluidization backfilling method in the Kanto region and is inexpensive, and a fluidized soil using the same.

[0006]

In the present invention, a solidifying material containing Portland cement, gypsum, quick lime, and alkali metal salt or alkaline earth metal salt components in a specific ratio is a soil containing volcanic cohesive soil. The inventors have found that they exhibit excellent properties for use in the fluidized backfilling method, and have solved the above problems. That is, the present invention relates to Portland cement 30.
~ 60 wt%, gypsum 20-40 wt%, quicklime 10-4
The present invention relates to a solidifying material for fluidized backfilling, which comprises 0% by weight and 0.2 to 7% by weight of an alkali metal salt or an alkaline earth metal salt. In addition, the present invention provides a fluidized soil in which the solidifying material for fluidization backfilling is added to volcanic ash cohesive soil having an adjusted water content ratio of 160 to 220%, or an adjusted water content ratio of 30 to 80.
%, And volcanic ash cohesive soil on a dry weight basis of 10 to
It relates to fluidized soil added to coarse-grained soil containing 30%. The present invention will be described in detail below.

Examples of Portland cement that can be used in the solidifying material of the present invention include early-strength, normal, moderate heat cements and sulfate resistant Portland cement. Among these, the early-strength cement is used. Is preferred.
The amount of Portland cement in the solidifying material is 30 to 60% by weight, preferably 40 to 50% by weight. When the amount of Portland cement is less than 30% by weight, sufficient medium / long-term strength cannot be obtained when applied to coarse-grained soil, and when it is more than 60% by weight, it has sufficient rapid hardening property against volcanic ash clay soil. Can't get

As the gypsum component, crushed products of anhydrous gypsum, gypsum dihydrate, and gypsum hemihydrate can be used singly or as a mixture regardless of the kind. The amount of gypsum in the solidified material is 2
It is 0 to 40% by weight, preferably 25 to 35% by weight.
If the amount of gypsum is less than 20% by weight, the long-term strength will be excessive when applied to coarse-grained soil, making re-drilling difficult and obtaining the required initial strength when applied to volcanic cohesive soil. I can't. On the other hand, if the amount of gypsum is more than 40% by weight, not only the necessary initial strength cannot be obtained, but also
The treated soil may undesirably expand excessively.

As quick lime which is another constituent of the solidifying material of the present invention, soft burned quick lime granular products and powdered products, and hard burned quick lime powdered products can be preferably used.
As soft-burnt quick lime granular products, which are generally used for ground improvement, etc., 1 mm, 3 mm and 5 mm under products, and powdered products, both soft-baked and hard-baked 200 (74 μm), 100 (14
9 μm) Mesh under products can be mentioned,
It is most preferable to use a powdered product of hard-baked quicklime because it has an excellent balance of fluidity and rapid hardening.

The proper amount of quicklime in the solidified material is 10-40.
% By weight, but it may be adjusted according to the degree of firing and particle size of quicklime, for example, 25 for soft-burnt quicklime granules.
-40, 10 to 20 for soft burned lime powder, and 15 to 30 for hard burned lime powder. If the amount of quick lime is too small, the desired initial strength cannot be obtained, and if it is too large, it becomes difficult to secure the fluidity of the treated soil. If the particle size of quicklime is made finer than the above, or conversely coarser, the desired fluidity and initial strength may be obtained even if the amount is out of the range of 10 to 40% by weight, but the traffic can be opened. It is not preferable because the short and medium-term strength cannot be obtained, or the long-term strength becomes high to the extent that re-drilling is impossible.

The solidifying material of the present invention includes sodium sulfate or
Uses magnesium sulfate . This is because it has no deliquescent property and has little effect on short-term strength when a large amount is added. As magnesium sulfate, any of anhydrous salt, monohydrate, and heptahydrate can be used, but it is preferable to use heptahydrate which is easily available. The amount of sodium sulfate or magnesium sulfate added was 0.
The amount is 2 to 7% by weight, but is appropriately determined within this range in consideration of the effects of the molecular weight, the amount of water of crystallization and the dissolution rate. 0.2% by weight of sodium sulfate or magnesium sulfate
If it is less, it is difficult to secure the required fluidity, and if it is more than 7% by weight, not only the short-term strength decreases but also the excavation soil treatment cost increases.

The solidifying material of the present invention treats volcanic ash cohesive soil or soil containing volcanic ash cohesive soil as a main component, but volcanic ash cohesive soil is classified into volcanic ash cohesive soil type I, It is classified into three types: volcanic ash clay type II and organic volcanic ash soil. The solidifying material of the present invention can be applied to any of the three types as long as the water content ratio is adjusted within the range of the present invention. Among them, the natural water content is 80 to 130%,
It can be used particularly suitably for Kanto loam classified as volcanic ash type II. Water content ratio of the soil to be processed is 160 to 220 percent in the case of ash quality cohesive soil, is good to adjust the 30% to 80% in the case of coarse soil volcanic ash quality cohesive soil is mixed
Yes . If the water content ratio is smaller than this range, the fluidity of the treated soil cannot be secured, and if it exceeds this range, the solidification is insufficient and the desired initial strength cannot be obtained, which is not preferable.

[0013] The amount of the solidifying material of the present invention, soil solidification target soil, it will be determined in consideration of the target specification to comprise the treated soil, treated soil 1 m ³ per volcanic ash quality Clay 100 to 150 kg, and 70 to 120 kg for coarse-grained soil mixed with volcanic ash cohesive soil. If the amount of the solidifying material used is too small, the solidification is insufficient and the desired initial strength cannot be obtained, and if it is too large, it becomes difficult to secure the fluidity of the treated soil, which is not preferable.

The coarse-grained soil has a coarse-grained content of 50% or more, which is defined by the Japan Unified Classification prescribed by the Geotechnical Society. The amount of the volcanic ash cohesive soil mixed with the coarse-grained soil is 10 to 30% based on the dry weight of both the coarse-grained soil and the volcanic ash cohesive soil. If it is less than 10%, the required rapid hardening cannot be obtained, and if it exceeds 30%, not only the effect of improving the solidification property corresponding to the added amount is not exhibited, but conversely the strength is lowered and the excavated soil treatment cost is increased.

In using the solidifying material of the present invention, a high-performance water reducing agent and a fluidizing agent may be used in combination for the purpose of improving the fluidity of the treated soil and the soil recovery rate. Further, when it is necessary to maintain the fluidity for a long time, a known set retarder can be used in combination.

The quicklime existing in the solidified material of the present invention reacts with volcanic ash cohesive soil to form ettringite and the like in the presence of gypsum, and contributes to the development of initial strength. In addition, the heat generated by consumption of quick lime increases the reaction rate of the entire system.
On the other hand, Portland cement mainly contributes to the development of moderate and long-term strength, and its hydration reaction is also accelerated by quicklime. Alkali metal salts such as magnesium sulfate and alkaline earth metal salts control the rapid reaction between quick lime and volcanic ash cohesive soil to impart appropriate fluidity to the treated soil.

The fluidity and the initial strength development required for the fluidized backfilling method mainly depend on the reaction rate of quicklime.
The reaction rate of this quick lime varies depending on the firing degree and particle size, and depending on it, the optimum addition amount exists as described above. Since the solidifying material of the present invention regulates the amounts of gypsum, Portland cement and alkali metal or alkaline earth metal salt in accordance with the reaction characteristics of quicklime, it exhibits excellent fluidity, rapid hardening and moderate long-term strength. It is supposed to do. Further, the solidifying material of the present invention has a small effect on excavated soil other than volcanic ash cohesive soil, but for coarse-grained soil, not only can it be solidified by adding an appropriate amount of volcanic ash cohesive soil, but the required amount of solidifying material Is also a major feature.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to specific examples. (1) Preparation of tone made solidifying material solidifying material used the ingredients shown below. Portland Cement: Early Strength Portland Cement Quick Lime: Soft Calcined Lime 0 to 1 mm Product and 100
Mesh under product Hard baked lime 100 Mesh under product Anhydrous gypsum: Thai natural type II anhydrous gypsum magnesium sulfate: commercial product 7 hydrate sodium sulfate: commercial product reagent special grade 10 hydrate prescribed amount of cement, gypsum, quicklime and magnesium sulfate or 3 min <br/> placed sodium sulfate in a polyethylene bag, hand mixed, shown in Table 2 (example 15 species) and Table 3 (Comparative example 10 species), a different 25 types of solidifying material composition Obtained.

(2) Soil treatment with solidifying material The two types of test soil used are shown in Table 1.

[0020]

[Table 1]

Examples 1 to 15 and Comparative Examples 1 to 10 In a thermostatic chamber at 20 ° C., 40 parts by weight of tap water was added to 100 parts by weight of Kanto loam, and the mixture was stirred and mixed to obtain a water content of 180%.
Was prepared. 14 parts by weight of solidifying material (130 kg / m ³ ) having the composition shown in Tables 2 and 3 was added to this slurry.
Was added and mixed by stirring for 1 minute with a Hobart mixer to obtain treated soil. Examples 16 and 17 and Comparative Examples 11 to 13 Coarse-grained soil shown in Table 1, Kanto loam and tap water were mixed in a thermostatic chamber at 20 ° C., and the amount of tap water was changed according to the mixing ratio of the two soils. The water content of the slurry was adjusted by adjusting the water content. The same solidifying material as that used in Example 2 in Table 2 was added to the produced slurry at a rate of 100 kg / m ³ , and the mixture was stirred and mixed with a Hobart mixer for 1 minute to obtain a treated soil.

(3) Characteristic Measurement of Treated Soil Flowability: The treated soil immediately after kneading and after 3 minutes was measured by the Kodan 305 cylinder method which is a standard of the Highway Public Corporation. Uniaxial compressive strength: 50 mm inside diameter of treated soil, 100 mm height
Pour into the cylindrical formwork of 30 ℃ considering the heat of the treated soil
Then, the uniaxial compressive strength was measured in accordance with JCAS L-01 "Test method for stable treated soil by cement-based solidifying material". Measurement of adiabatic temperature rise: For Examples 3 and 4, the adiabatic temperature rise of the treated soil after addition of the solidifying material was measured. Adiabatic calorimeter [Tokyo Riko Co., Ltd., ACM-126]
Was performed using. The measurement results of fluidity and uniaxial compression strength are shown in Table 2 (Examples 1 to 15), Table 3 (Comparative Examples 1 to 10) and Table 4 (Examples 16 and 17, Comparative Examples 11 to 13), and the heat insulation The temperature rise measurement result is shown in FIG.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

As shown in the examples of Table 3, the fluidized soil obtained by adding the solidifying material of the present invention to the volcanic ash clay soil,
Immediately after kneading and 3 minutes after kneading, the flow value is 150
It is in the range of up to 200 mm and has sufficient fluidity for filling around a buried pipe such as a gas pipe. The uniaxial compressive strength after molding is 30 minutes later: about 0.2 to 0.6 kgf / c.
m ^2, 4 hours later: a 0.9~1.4kgf / cm ^2, the recovery operation by short time leveling laid sand surface compaction after backfilling the processing soil showed fast curing possible . Also 28
The uniaxial compressive strength after day is about 3 to 6 kgf / cm ² , which is within the re-excavable strength. In addition, in the adiabatic temperature rise curves for Examples 3 and 4 shown in FIG. 1, rapid heat generation ends within 1 hour after kneading, and solidification by the treatment material of the present invention is effective within a short time after kneading. And it shows that it progresses efficiently. On the other hand, the fluidized treated soil to which the solidifying material having the composition outside the scope of the claims of the present invention, which is shown in the comparative example of Table 3, does not show the necessary fluidity or is treated for 30 minutes or 4 hours. The subsequent uniaxial compressive strength is too small to show favorable results.

On the other hand, as for the coarse-grained soil, as shown in the examples of Table 4, the fluidized soil in which the volcanic ash cohesive soil was added and the water content ratio was adjusted and then the solidifying material of the present invention was added,
The flow value is 170 immediately after the end of kneading and 3 minutes after the end of kneading.
The uniaxial compressive strength after molding is 30 minutes: about 0.2 to 0.3 kgf / cm, in addition to having fluidity that allows filling around gas pipes and the like. ^Two , four
After time: 0.9 to 1.4 kgf / cm ² , which showed rapid hardening that enables restoration work such as compaction of the sand layer on the treated soil in a short time after placing. The uniaxial compressive strength after 28 days is about 7
It remained within the re-excavable strength of ~ 8 kgf / cm ² .
On the other hand, the fluidized soil having a composition in which the addition amount or water content of the volcanic ash cohesive soil shown in Comparative Example has a composition outside the scope of the claims of the present invention shows sufficient fluidity, but 30 minutes after the treatment. Even after 4 hours, not only does not develop sufficient uniaxial compressive strength to withstand the subsequent process, but also the uniaxial compressive strength after 28 days becomes too high to make re-drilling difficult, which does not show favorable results. .

[0028]

EFFECTS OF THE INVENTION The solidifying material of the present invention has excellent fluidity and quick-hardening property for solidifying soil containing volcanic ash cohesive soil, and exhibits long-term strength that allows re-excavation even after hardening. Therefore, it can be suitably used for a fluidized backfilling method for excavation sites associated with burying and repairing water and sewer pipes, gas pipes, electric wiring, telephone lines, etc. in city streets in the Kanto region whose main component is volcanic ash soil. Also, for coarse-grained soil, fluidized soil having a rapid hardening property can be obtained by mixing an appropriate amount of volcanic ash cohesive soil. Further, since expensive special materials such as calcium aluminate and calcium sulfaluminate are not used, the cost of the solidifying material can be greatly reduced.

[Brief description of drawings]

FIG. 1 shows an example of an increase in adiabatic temperature associated with solidification of soil treated with the solidifying material of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI // E02D 3/00 101 E02D 3/00 101 C09K 103: 00 C09K 103: 00 (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 28/14 C04B 22/06 C04B 22/10 C04B 22/14 C09K 17/02 C09K 17/06 C09K 17/10 E02D 3/00

Claims (5)

(57) [Claims] 1. Portland cement 30 to 60% by weight,
Gypsum 20-40% by weight, quick lime 10-40% by weight and sulfur
Sodium acid salt or magnesium sulfate 0.2 to 7% by weight
Ri More forming, is inevitably introduced mixed thereto or the like material
Do not include aluminum compounds other than aluminum compounds
Volcanic ash cohesive soil or volcanic ash soil
Fluidized landfill for soil containing 10 to 30% of dry soil based on dry weight
Solidifying material for return. 2. A fluidizing backfill solidifying material according to claim 1,
Fluidized soil added to volcanic ash cohesive soil with adjusted water content of 160-220%. 3. The fluidized soil according to claim 2, wherein the amount of the fluidizing and backfilling solidifying material added to the volcanic ash clay soil is 100 to 150 kg / m ³ . 4. The solidifying material for fluidized backfill according to claim 1,
Fluidized soil having an adjusted water content ratio of 30 to 80% and added to coarse-grained soil containing 10 to 30% of volcanic cohesive soil on a dry matter basis. 5. The fluidized soil according to claim 4, wherein the amount of the fluidizing and backfilling solidifying material added to the coarse-grained soil is 70 to 120 kg / m ³ .