JP2016112540A - Water sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide water sealing material capable of improving strength by a fiber addition amount less than conventional one, and a having high deformation following property.SOLUTION: Water sealing material is obtained by mixing viscous soil (at inner split volume ratio of 70 to 90%) adjusted to moisture ratio of 100 to 300% and steel-making slag (at inner split volume ratio of 10 to 30%) of a particle diameter of 26.5 mm or less, and further adding fibrous material at outer split volume ratio of 0.1 to 1.0%.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a water shielding material applicable to a water shielding work such as an industrial waste disposal site.

  Conventionally, as a water shielding material for water shielding works such as industrial waste disposal sites, low-strength, high-deformability soil-based water-insulating materials consisting of viscous soil, bentonite, fibers, or viscous soil, cement-based solidified material, A high-strength and low-deformability solidified soil impervious material composed of fibers has been proposed. Patent Document 1 proposes a water shielding material made of a fibrous material such as marine clay suspension, bentonite, silicates, etc. as a deformation-following water shielding material. It has been pointed out that this water shielding material is excellent in deformation followability but lacks stability when applied to a water shielding structure because of its low strength.

In order to solve the above problem, Patent Document 2 proposes a water shielding structure using a water shielding material having both strength and deformation followability. This water shielding material is made by adding solidified material (50 to 150 kg / m ³ ) and short fibers (volume ratio 0.2 to 2.0%) to viscous soil containing water, and is weakly deformed to solidified soil with high water barrier properties. Follow-up is given.

JP 2002-336811 A JP 2006-326392 A

The deformation follow-up water shielding material of Patent Document 1 has a high deformation follow-up property, but has a weak point that the strength is small. The water shielding structure of Patent Document 2 has the following problems as a result of imparting strength to the water shielding material.
(1) In order to impart sufficient toughness, it is necessary to increase the amount of short fibers added, leading to high costs.
(2) If large strain occurs due to ground deformation due to earthquakes during construction and operation, subsequent strength recovery cannot be expected.

  An object of this invention is to provide the water shielding material which can improve an intensity | strength with the fiber addition amount smaller than before, and has a high deformation followability in view of the problem of the above prior art.

  In order to achieve the above objectives, the water shielding material consists of viscous soil (70-90% by internal volume ratio) with a moisture content adjusted to 100-300% and steelmaking slag with a particle size of 26.5mm or less (by internal volume ratio). 10 to 30%) and a fibrous substance is further added in an external volume ratio of 0.1 to 1.0%.

  According to this water shielding material, strength can be improved by mixing steelmaking slag with cohesive soil, and even when subjected to large strains due to ground deformation due to earthquakes, etc. during construction and in service The strength can be recovered with the increase of. In addition, since the fibrous substance is easily entangled with the steelmaking slag, which is a granular material, high deformation followability can be imparted with a small addition amount of the fibrous substance. As described above, the strength can be improved with a smaller amount of fibrous material than in the prior art, and high deformation followability can be obtained. The water shielding material is a material suitable for a water shielding work such as an industrial waste disposal site.

  If the moisture content of the cohesive soil is 100% or more, workability with steelmaking slag and fibrous materials is good without deterioration, and if the moisture content is 300% or less, strength and water impermeability are not lowered. It is. When the steelmaking slag is mixed at a volume ratio of 30% or less, the workability is good without decreasing, and when the volume ratio is 10% or more, an improvement in water shielding can be expected. Further, when the addition amount of the fibrous substance is 0.1% or more by volume, preferably when the volume ratio is 0.2% or more, an effect of imparting deformation followability can be obtained, and the addition amount is 1.0% by volume. If it is below, the amount of addition is not increased and the cost is not so high.

  In the water shielding material, it is preferable to add a small amount of a dispersant for the purpose of improving fluidity.

  In addition, the water shielding material may have a characteristic that the compressive stress does not decrease when the compressive strain is 5% or 5% or more in the uniaxial compression test. By having such characteristics, it can be said that the water shielding material has high deformation followability.

  According to the present invention, it is possible to provide a water shielding material that can improve the strength with a smaller amount of fiber addition than before and has high deformation followability.

It is sectional drawing which shows roughly the principal part of the sea surface industrial waste disposal site to which the water-shielding material by this embodiment is applied. It is a graph which shows the stress-strain diagram obtained from the uniaxial compression test for the confirmation of a deformation | transformation followability in a present Example. For comparison with this example in FIG. 2, quoted from “Kotake / Urayama / Matsubara“ Bending / Tensile Strength Properties of Solidified Soil ”, Geosynthetics, 27, 133-140, 2013)”. It is a graph which shows the stress-strain diagram of the uniaxial compression test of the cement solidification processing soil which mixed the short fiber. It is a graph which shows the stress strain diagram obtained from the uniaxial compression test for confirmation of the intensity | strength recoverability in Example 7. FIG. It is a graph which shows the stress-strain diagram obtained from the uniaxial compression test in the comparative example 2 for comparing with the Example 7 of FIG. It is a graph which shows the stress-strain diagram obtained from the uniaxial compression test in the comparative example 3 for comparing with Example 7 of FIG. It is a graph which shows the relationship between the steelmaking slag addition amount obtained from the flow test for confirmation of the workability in a present Example, and a flow value.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a main part of an industrial waste disposal site to which a water shielding material according to this embodiment is applied.

As shown in FIG. 1, the revetment 1 of the sea surface industrial waste disposal site of this embodiment includes a mound 2 constructed from rubble on the bottom G, a caisson 3 installed on the mound 2 and facing the sea water A side. The backfill 4 constructed from rubble on the back side (inside water B side) of the caisson 3, the water shielding layer 5 provided on the back side (inside water B side) of the backfill 4, and the inside of the water shielding layer 5 And a steel pipe sheet pile 6 placed on the water B side from the bottom G to the ground. The water-impervious layer 5 and the steel pipe sheet pile 6 constitute a side water-impervious construction for a sea surface industrial waste disposal site. A water-impervious layer 7 is provided on the bottom G1 of the internal water B, and constitutes a bottom impermeable work for a sea surface industrial waste disposal site. The water-impervious layer 5 and the water-impervious layer 7 are made of the water-impervious material according to the present embodiment. In addition, in FIG. 1, when the water bottom ground is a continuous water-impermeable formation with a thickness of 5 m or more and a water permeability coefficient of 1.0 × 10 ⁻⁷ m / s or less, for example, Can be omitted.

  The water-impervious material according to the present embodiment has a viscous soil (internal volume ratio 70-90%) adjusted to a moisture content of 100-300% and a steelmaking slag having a particle size of 26.5 mm or less (internal volume ratio 10-30). %) And fiber (fibrous substance) is added in an external volume ratio of 0.1 to 1.0%, and a small amount of a dispersant is added for the purpose of improving fluidity.

  In addition to dredged soil, purchased materials such as mountain clay and bentonite can be used as the clay. Use with water content adjusted to 100-300%.

  The steelmaking slag described above has a particle size of 26.5 mm or less, and the mixing amount of the steelmaking slag is adjusted in the range of 10 to 30% (volume ratio) according to the target strength and water shielding. In addition, it is preferable to use the converter system steelmaking slag which is a granular material produced | generated at the process of refining pig iron manufactured with the blast furnace with a converter as steelmaking slag. Further, the steelmaking slag may contain gravel having a particle size of 26.5 mm or less.

  The type of the above-mentioned fibers is arbitrary, and for example, synthetic fibers such as polyester, polypropylene, polyethylene, and vinylon, glass fibers, and carbon fibers can be used. The fiber dimensions are also arbitrary. The addition amount is adjusted in the range of 0.1 to 1.0% by volume ratio.

  As the above-mentioned dispersant, for example, a polyacrylic acid, carboxymethylcellulose, hydroxypropylmethylcellulose or the like as a main component can be used, but is not limited thereto.

  Next, an example of the construction method of the water shielding layer 5 and the water shielding layer 7 of FIG. 1 is demonstrated. However, the construction method is not limited to this example, and may be another method.

(1) Mud control Add a predetermined amount of seawater or fresh water to clay soil such as dredged soil, and adjust the moisture content to the desired level.

(2) Kneading The adjusted mud is sent to a mixer, and steelmaking slag / short fibers are added and kneaded at a predetermined volume ratio to produce a water shielding material.

(3) Pressure feed The manufactured water-impervious material is transported to a placement site by a pressure feed pipe using a pressure feed pump.

(4) Placing a water shielding material at a predetermined position using a tremely pipe. That is, the water shielding layer 5 and the water shielding layer 7 are constructed by placing a water shielding material at positions corresponding to the water shielding layer 5 and the water shielding layer 7 in FIG.

  According to the water shielding material according to the present embodiment, high deformation followability can be imparted with a smaller amount of added fiber than in the prior art. In Patent Document 2, the strength and toughness of the water shielding material is improved by cement-based solidified material (fine powder) and short fibers (volume ratio 0.2-2% added), whereas the water shielding material according to the present embodiment. In addition to improving strength by mixing steelmaking slag, deformation followability is improved by making fibers easily entangled with steelmaking slag, which is a granular material, and high deformation followability with a small fiber addition amount of 0.1 to 1.0% in volume ratio Can be granted.

  In addition, the water shielding material according to the present embodiment recovers its strength as the material age increases even when it is subjected to a large strain due to ground fluctuation due to an earthquake or the like during construction and operation. The material mixed with steelmaking slag and cohesive soil increases in strength over the long term, but the water shielding material according to this embodiment is a material that exhibits an internal restraint effect by adding fibers and does not brittle fracture, so it is large. Even when subjected to strain, it is possible to draw out the long-term strength development characteristics of steelmaking slag and to promote an increase in strength over time (strength recovery). On the other hand, when the fiber is not added, the strength does not recover because the contact force on the fracture surface is lost due to brittle fracture.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to a present Example. In this example, the deformation following property, strength recovery property, workability by flow test, and water shielding property of the water shielding material were confirmed.

[Deformability tracking]
The mixed impervious material for fiber and steelmaking slag of this example is made of steelmaking slag (particle size for laboratory tests) on clay (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a moisture content of 160%. 9.5 mm or less) and polyester short fibers (fiber length 20 mm, fiber diameter 14.8 μm, specific gravity 1.38 g / cm ³ ) mixed at a predetermined volume ratio. In Examples 1 to 6, the blending ratio of the short fibers was changed in six steps from 0.1 to 1.0% by volume, and in Comparative Example 1, no short fibers were blended. The formulations for Examples 1-6 and Comparative Example 1 are shown in Table 1 below.

  As shown in Table 1, a fiber / steel slag mixed water-insulating material with the amount of added fiber as a parameter was prepared, and a uniaxial compression test was carried out 7 days after curing. A stress strain diagram obtained from this uniaxial compression test is shown in FIG. The uniaxial compression test was performed based on JIS A 1216.

  From the results of FIG. 2, in Comparative Example 1 in which the short fibers were not mixed, the compressive stress decreased before reaching 5% compressive strain, whereas the short fibers were 0.2% or more by volume as in Examples 2-6. It can be seen that when added, the material does not decrease in compressive stress even at a large strain level of 5% or more. Moreover, in Example 1 which added 0.1% of short fibers by volume ratio, when a compressive strain is 5%, it turns out that a compressive stress does not fall. In Examples 2 to 6 in which the fiber addition amount is 0.2 to 1.0% by volume, it can be seen that the compressive stress retention effect is increased at a large strain level of 5% or more depending on the fiber addition amount. That is, when the amount of added fiber is increased, the deformation followability is improved.

  From the above, the fiber / steel slag mixed water-insulating material of Examples 1 to 6 is obtained by adding 0.1 to 1.0% of short fibers by volume ratio, preferably by adding 0.2 to 1.0% of short fibers by volume ratio. It can be seen that the compressive strain is 5% or 5% or more and the compressive stress does not decrease and has high deformation followability.

  For comparison, the results of a uniaxial compression test of cement-solidified soil mixed with short fibers are shown in Fig. 3 (Kotake, Urayama, Matsubara "Bending and tensile strength characteristics of solidified soil", Geosynthetics papers 27, 133-140, 2013). From Fig. 3, in the case of cement-solidified soil, even when 1.0 vol% of short fibers are added, the compressive stress decreases with increasing axial strain after showing the maximum compressive stress at about 2% axial strain. It can be seen that there is a tendency to deform and the deformation followability is reduced.

[Strength recovery]
The mixed water-impervious material for fiber and steelmaking slag of Example 7 was made of steelmaking slag (particle size for laboratory tests) in clay (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a moisture content of 160%. 9.5 mm or less) and polyester short fibers (fiber length 20 mm, fiber diameter 14.8 μm, specific gravity 1.38 g / cm ³ ) mixed at a predetermined volume ratio. In Comparative Example 2, short fibers are not mixed. In Comparative Example 3, in order to investigate the strength recovery of cement-solidified soil mixed with fibers, blast furnace cement type B (75 kg / m ³ ), polyester short fibers (fiber length) were adjusted to a moisture content adjusted to 160%. 20 mm, fiber diameter 14.8 μm) is added to the fiber-mixed cement solidified soil with a predetermined volume ratio. The following Table 2 shows each formulation.

Here, in Example 7, the added amount of fiber is close to the median value of the added amount of fiber (0.1 to 1.0% by volume) defined by the water shielding material, and the deformation followability has already been evaluated in FIG. Since it has been completed, the volume ratio was set to 0.5%. In addition, in order to compare the recoverability of strength depending on whether or not the fiber was added, the case where the fiber addition amount of Comparative Example 2 was set to 0% was also evaluated. On the other hand, for the amount of cement added when the cement of Comparative Example 3 was used, the result of the fiber addition volume ratio 0.5% in FIG. 2 was referred to. In other words, the maximum value of compressive stress at the fiber addition volume ratio of 0.5% (age 7 days) in Fig. 2 is 170 kN / m ^2. A cement amount of about 200 kN / m ² was added.

  Strength recovery was evaluated by a uniaxial compression test according to JIS A 1216. In the evaluation method, a specimen cured for 28 days was uniaxially compressed (virgin compression) to a strain level of 5%, and then the loading was temporarily stopped, the specimen was taken out, exposed for 85 days, and then subjected to a uniaxial compression test again. The exposure method is based on a method (air exposure) that wraps the specimen with a wrap to prevent drying. The reason for setting the virgin compression strain level to 5% is that for a specimen with 0% added fiber, if a compressive strain exceeding 5% is applied, the specimen collapses when the specimen is removed and prepared for exposure. This is because there is a risk of doing so.

  Stress strain diagrams obtained from the uniaxial compression test as described above are shown in FIGS. In addition, the compressive stress of the vertical axis | shaft of FIGS. 4-6 is normalized (compressive stress ratio) with the maximum value of the compressive stress in 5% or less of compressive strain. 4 showing the result of Example 7 and FIG. 5 of Comparative Example 2 in which short fibers are not mixed, by adding steelmaking slag and short fibers to the clay, the uniaxial compressive strength during virgin compression is increased. It can be seen that the strength recovery exceeds the limit, and that the strength is not recovered only by mixing the steelmaking slag (without mixing the short fibers).

  Moreover, when FIG. 4 which shows the result of Example 7 and FIG. 6 of the comparative example 3 of the cement solidification material which mixed the short fiber are compared, even when the fiber is added, the cement solidification treated soil is subjected to virgin compression after recompression. It can be seen that no strength recovery exceeding the uniaxial compressive strength occurs.

[Workability by flow test]
The fiber / steel slag mixed water-insulating material of Examples 8, 9, 10 and Comparative Example 4 is made of steel (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a moisture content of 160%. Slag (adjusted to a particle size of 9.5 mm or less for laboratory tests) and polyester short fiber (fiber length 20 mm, fiber diameter 14.8 μm, specific gravity 1.38 g / cm ³ ) are mixed at a specified volume ratio, In order to improve, 2 kg / m ^{3 of} a dispersant mainly composed of polyacrylic acid is added. A flow test was conducted on these water shielding materials to examine the workability of the materials. The flow test was performed based on the cylinder method specified in JHS313-1999 (Japan Highway Public Corporation Standard Air Mortar and Air Milk Test Method). The formulation is shown in Table 3 below.

  FIG. 7 shows the result of the flow test. From FIG. 7, it can be seen that as the amount of steelmaking slag added increases, the flow value decreases and the workability decreases. Here, in this water-impervious material, the flow value is defined as 85 mm or more as an index of good workability, but in Examples 8 to 10, the flow value is 87 mm or more and is the specified value or more. On the other hand, in Comparative Example 4 with a steelmaking slag volume ratio of 40% blended with a flow value of 81 mm, it was confirmed that the sample was hard and kneading was difficult. From the above results, it can be said that the upper limit value of the steelmaking slag addition amount in the water shielding material is 30% by volume from the viewpoint of ensuring good workability.

[Waterproof]
The fiber / steel slag mixed water-insulating material of Examples 11, 12, 13 and Comparative Example 5 is made of steel (soil particle density 2.633 g / cm ³ , liquid limit 101.3%) adjusted to a moisture content of 160%. Slag (adjusted to a particle size of 9.5 mm or less for laboratory tests) and polyester short fibers (fiber length 20 mm, fiber diameter 14.8 μm, specific gravity 1.38 g / cm ³ ) are mixed at a predetermined volume ratio. We measured the permeability coefficient of these fiber / steel slag mixed impervious materials, and evaluated the applicability as a water impervious material for waste disposal sites. For this purpose, a water level permeability test was carried out based on JIS A 1218, and three methods were referred to the description of “Ground material test method and explanation, page 525, issued on November 25, 2009 (Geotechnical Society)”. A water permeability test using an axial compression test apparatus was performed. The former was applied in the case where the specimen was not self-supporting because of insufficient shear strength, and the latter was applied otherwise. Table 4 below shows the formulation and test results.

The conditions for the impervious material at the waste disposal site are “layer thickness of 5 m or more, permeability coefficient of 1.0 × 10 ⁻⁷ m / s or less” for bottom impermeable construction, and “layer thickness of 0.5 m for side impermeable construction” As mentioned above, it is said that the permeability coefficient is 1.0 × 10 ^-8 m / s or less. ”(Portrait of Port Space Advancement Center“ Management Waste Landfill Revetment Design, Construction and Management Manual (Revised Version) ”, pages 36-37 , 2008). From these regulations, it can be seen that if the required layer thickness is ensured according to the hydraulic conductivity, it will be established as a water shielding material, but here, assuming a bottom water shielding material, `` layer thickness 5 m or more, hydraulic conductivity 1.0 × “10 ^-7 m / s or less” is considered as one target value.

From the results in Table 4, it can be seen that the water permeability of the water shielding material is improved when the amount of steelmaking slag added is increased. In Comparative Example 5 in which the amount of steelmaking slag added is 5% by volume, it can be seen that the target water shielding property cannot be achieved. On the other hand, in Examples 11, 12, and 13 in which the amount of steelmaking slag added was 10% or more by volume ratio, the water permeability coefficient was 1.0 × 10 ⁻⁷ m / s or less, which satisfies the target water barrier property. Recognize. From the above results, it can be said that the lower limit value of the steelmaking slag addition amount in the water shielding material is 10% by volume ratio.

  As mentioned above, although the form and Example for implementing this invention were demonstrated, this invention is not limited to these, A various deformation | transformation is possible within the range of the technical idea of this invention. For example, the structure of the revetment and the impermeable construction of the sea surface industrial waste disposal site in FIG. 1 is an example, and the water shielding material of the present invention can of course be applied to other structures.

  Further, the water shielding material according to the present invention can be applied as a water shielding material for a water shielding work at an industrial waste disposal site (land and sea surface), but is not limited thereto, and can be appropriately applied to other facilities and structures. Of course, for example, it can be used as a water-blocking material filling the joints of vertical water-blocking walls and as a containment material for contaminated soil. Applicable to.

  According to the present invention, it is possible to realize a water shielding material that can improve strength and have high deformation followability with a smaller amount of fiber addition than in the past. Water material can be provided.

DESCRIPTION OF SYMBOLS 1 Revetment 2 Mound 3 Caisson 4 Backfill 5 Water shielding layer 6 Steel pipe sheet pile 7 Water shielding layer A Sea water B Inside water G, G1 Bottom

Claims (3)

  Cohesive soil with a water content adjusted to 100-300% (70-90% by internal volume ratio) and steelmaking slag with a particle size of 26.5mm or less (10-30% by internal volume ratio) are mixed, and fiber Water shielding material with 0.1 to 1.0% added by volume ratio.   The water shielding material according to claim 1, further comprising a dispersant added for improving fluidity.   The water shielding material according to claim 1 or 2, which has a characteristic that a compressive strain does not decrease when a compressive strain is 5% or 5% or more in a uniaxial compression test of the water shielding material.

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