JP2001226958A - Steel pipe concrete pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight steel pipe concrete pile which can be driven easily as a foundation pile. SOLUTION: A concrete portion is a steel pipe concrete pile comprising a hardened body of blended matters containing at least water, cement, pozzolan type fine powder, fine aggregates of at most 2 mm a water reducing admixture. In addition, it is desire to contain metal fibers and/or organic fibers, inorganic powder having a mean grain size of 3 to 20 μm, fibrous particles or flake type particles with mean grading of 1 mm or finer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel pipe having an outer shell,
The present invention relates to steel pipe concrete piles lined with ultra-high-strength concrete exceeding 130 MPa in compressive strength.

[0002]

2. Description of the Related Art Conventionally used steel pipe concrete piles have a steel pipe as an outer shell and a high-strength concrete with a compressive strength of about 80 MPa lining inside, so that the bending resistance and the bending rigidity are particularly large and large. It is used as a foundation pile on which a bending moment or a shear force acts, or as a foundation pile when displacement limitation is large.

[0003]

However, the above-mentioned conventional steel pipe concrete pile (having a high-strength concrete with a compressive strength of about 80 MPa lining on the inside) described above,
1) For example, in the case of a large steel pipe concrete pile with an outer diameter of 600 mm, the concrete thickness is as thick as 80 to 90 mm, the weight of the steel pipe concrete pile increases, and it takes time to transport and the like. In addition, the thickness of the pile is as thick as about 100 mm, and it takes time to drive as a foundation pile. 2) Intumescent materials are usually used to prevent drying shrinkage of the concrete and to improve the adhesion between the steel pipe and the concrete.However, care must be taken to avoid excessive chemical prestress due to the use of intumescent materials. is there. There were drawbacks such as.

[0004] Therefore, there has been a demand for a steel pipe concrete pile which can reduce the thickness of concrete and does not require the use of an expanding material.

[0005]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems, and as a result, has solved the above-mentioned problems by lining the inside of a steel pipe with a compound combining specific materials. The inventors have found that the present invention can be performed, and have reached the present invention.

That is, the present invention provides a steel pipe concrete pile in which the concrete portion is made of a hardened material of a compound containing at least cement, pozzolanic fine powder, fine aggregate having a particle size of 2 mm or less, a water reducing agent, and water. Item 1), and the composition further comprises metal fibers and / or organic fibers (Claim 2).
Inorganic powder having an average particle size of 3 to 20 μm (claim 5), an average particle size of 1
It is preferable to include fibrous particles or flaky particles having a diameter of not more than mm (claim 6) and coarse aggregate (claim 7).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The type of cement used in the present invention is not limited, and various types of Portland cement such as ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, low-heat Portland cement, etc. and mixed cements such as blast furnace cement and fly ash cement are used. can do. In the present invention, if it is intended to improve the early strength of the cured product, it is preferable to use an early-strength Portland cement, and if it is intended to improve the fluidity of the composition, a moderate heat Portland cement or a low heat Portland cement is used. It is preferred to use.

[0008] Pozzolanic fine powder includes silica fume, silica dust, fly ash, slag, volcanic ash,
Silica sol, precipitated silica and the like. Generally, silica fume and silica dust have an average particle size of 1.0
It is suitable for the pozzolanic fine powder of the present invention because it is not more than μm and does not need to be ground. The blending amount of the pozzolanic fine powder is preferably 5 to 50 parts by weight with respect to 100 parts by weight of cement from the viewpoint of reducing the strength of the cured product and the amount of drying shrinkage. When the amount of the pozzolanic fine powder is small, strength developability is reduced. When the addition amount of the pozzolanic fine powder increases, the unit water amount increases, so that the strength developability also decreases.

In the present invention, fine aggregate having a particle size of 2 mm or less is used. Here, the particle size of the fine aggregate in the present invention is an 85% weight cumulative particle size. When the particle size of the fine aggregate exceeds 2 mm, the strength of the concrete decreases. In the present invention, it is preferable to use fine aggregate having a maximum particle size of 2 mm or less, and it is more preferable to use fine aggregate having a maximum particle size of 1.5 mm or less. As fine aggregate, river sand, land sand, sea sand, crushed sand, silica sand, and a mixture thereof can be used. The amount of the fine aggregate is preferably 50 to 250 parts by weight, more preferably 80 to 180 parts by weight, based on 100 parts by weight of cement, from the viewpoint of reducing the strength of the cured product and the amount of drying shrinkage.

As the water reducing agent, a lignin-based, naphthalene-sulfonic acid-based, melamine-based, polycarboxylic acid-based water reducing agent, an AE water reducing agent, a high performance water reducing agent or a high performance AE water reducing agent can be used. Among these, it is preferable to use a high performance water reducing agent or a high performance AE water reducing agent having a large water reducing effect. The compounding amount of the water reducing agent is preferably 0.5 to 4.0 parts by weight in terms of solid content based on 100 parts by weight of cement. If the amount of the water reducing agent (in terms of solid content) is less than 0.5 part by weight with respect to 100 parts by weight of cement, kneading becomes difficult, and the fluidity of the composition is low, and work such as molding is also difficult. Cement 100
If the amount of the water reducing agent (in terms of solid content) exceeds 4.0 parts by weight, the strength is reduced. The water reducing agent can be used in either liquid or powder form.

The amount of water is 10 to 3 parts per 100 parts by weight of cement.
The amount is preferably 0 parts by weight, more preferably 15 to 25 parts by weight. If the amount of water is less than 10 parts by weight with respect to 100 parts by weight of cement, kneading becomes difficult, and the flowability of the composition is low, and work such as molding is also difficult. If the amount of water exceeds 30 parts by weight with respect to 100 parts by weight of the cement, the strength decreases and the amount of drying shrinkage increases.

In the present invention, from the viewpoint of greatly increasing the bending strength of the cured product, it is preferable that the composition contains metal fibers and / or organic fibers. Examples of the metal fiber include a steel fiber and an amorphous fiber. Among them, the steel fiber is excellent in strength, and is preferable from the viewpoint of cost and availability. Metal fiber has a diameter of 0.01
~ 1.0mm, length 2 ~ 30mm is preferred. When the diameter is less than 0.01 mm, the strength of the fiber itself is insufficient, and the fiber tends to be cut when subjected to tension. If the diameter is more than 1.0 mm, the number of pieces with the same compounding amount decreases, and the effect of improving the bending strength decreases. If the length exceeds 30 mm, fiber balls tend to be formed during kneading. If the length is less than 2 mm, the effect of improving the bending strength decreases. The blending amount of the metal fiber is preferably less than 4%, more preferably less than 3% of the volume of the blend. When the content of the metal fiber increases, the unit water amount also increases in order to ensure workability during kneading, and the like, so that the above-mentioned amount of the metal fiber is preferable.

Examples of the organic fiber include vinylon fiber, polypropylene fiber, polyethylene fiber, aramid fiber, carbon fiber and the like. Organic fibers are 0.005-1.0m in diameter
m and a length of 2 to 30 mm are preferred. The blending amount of the organic fiber is preferably less than 10% of the volume of the blend, more preferably less than 8%. In the present invention, it is possible to use metal fibers and organic fibers in combination.

In the present invention, from the viewpoint of increasing the packing density of the cured product, the composition preferably contains an inorganic powder having an average particle size of 3 to 20 μm, more preferably 4 to 10 μm. Examples of the inorganic powder include quartz powder, limestone powder, carbide, and nitride. Among them, quartz powder is preferable from the viewpoint of cost and the stability of the quality of the cured product. Quartz powder, quartz or amorphous quartz,
Opal and cristobalite silica-containing powders and the like can be mentioned. The amount of the inorganic powder is determined based on the strength of the cured product.
50 parts by weight or less is preferable for 100 parts by weight of cement, and 2
0 to 35 parts by weight is more preferred.

In the present invention, from the viewpoint of increasing the toughness of the cured product, it is preferable that the composition contains fibrous particles or flaky particles having an average particle size of 1 mm or less. Here, the particle size of a particle is the size of its maximum dimension (in particular, its length for fibrous particles). Examples of the fibrous particles include wollastonite, bauxite, and mullite, and examples of the flaky particles include mica flake, talc flake, vermiculite flake, and alumina flake.
The blending amount of the fibrous particles or flaky particles is preferably 35 parts by weight or less, more preferably 10 to 25 parts by weight, based on 100 parts by weight of cement, from the viewpoint of the strength and toughness of the cured product. From the viewpoint of increasing the toughness of the cured product, it is preferable to use fibrous particles having a needleiness expressed by a length / diameter ratio of 3 or more.

In the present invention, the composition may contain coarse aggregate. For coarse aggregate, the particle size range
2.5 to 40 mm of gravel, crushed stone, mixtures thereof, and the like. The blending amount of the coarse aggregate is preferably 60 vol% or less in the blend, from the viewpoint of workability during kneading and the strength of the cured product,
% Or less is more preferable.

In the present invention, the method of kneading the compound is not particularly limited. For example, when coarse aggregate is not used, 1) materials other than water and water reducing agent are previously mixed (premix). The premix, water, and a water reducing agent are charged into a mixer and kneaded. 2) Materials other than water are mixed in advance (a premix, but a water reducing agent of a powder type is used), and the premix and water are charged into a mixer and kneaded. 3) Each material is individually charged into a mixer and kneaded. When using coarse aggregate: 1) Water, water reducing agent, materials other than coarse aggregate are previously mixed (premix), and the premix, water, water reducer, and coarse aggregate are put into a mixer, Knead. 2) Mix materials other than water and coarse aggregate in advance (premix, but use powder type water reducing agent)
The premix, water and coarse aggregate are put into a mixer and kneaded. 3) Each material is individually charged into a mixer and kneaded. And the like.

The mixer used for kneading may be of any type used for ordinary kneading of concrete, for example, an oscillating mixer, a pan-type mixer, a twin-screw mixer, or the like.

In the present invention, the method for forming the steel pipe concrete pile is not particularly limited. For example, 1) the compound may be poured into the outer shell of the steel pipe and centrifugally molded.2) The core is installed inside the steel pipe and the compound is poured between the steel pipe and the core to form. You may. In the present invention, a composition containing no coarse aggregate is referred to as JIS R
5201 (Physical test method of cement) 11. Flow test ”, the flow value measured without performing 15 dropping motions is 200 mm or more, which is excellent in fluidity, Pouring can be performed easily.
In the present invention, curing conditions are not particularly limited, and steam curing or the like may be performed.

Since the cured product of the composition of the present invention exhibits a compressive strength exceeding 130 MPa, the concrete thickness can be reduced and the steel pipe concrete pile can be reduced in weight.
In addition, since the pile can be made thinner, it can be easily driven as a foundation pile. Furthermore, since the amount of drying shrinkage of the cured product of the composition of the present invention is extremely small, it is not necessary to use an expanding material in order to enhance the adhesion between the steel pipe and the concrete.

[0021]

The present invention will be described below with reference to examples. 1. Materials used The following materials were used. 1) Cement; Low heat Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) 2) Pozzolanic fine powder; silica fume (average particle size 0.7 μm) 3) Fine aggregate: 2: 1 of silica sand 4 and silica sand 5 (weight ratio) 4) Metal fiber; steel fiber (diameter: 0.2 mm, length: 15 mm) 5) High-performance AE water reducing agent; polycarboxylic acid-based high-performance AE water reducing agent 6) Water; tap water 7) inorganic powder; quartz Flour (average particle size 7 μm) 8) Fibrous particles; wollastonite (average length 0.3 mm, length / diameter ratio 4) 9) Coarse aggregate; crushed stone 1505

Example 1 Low heat Portland cement 100 parts by weight, silica fume 3
2.5 parts by weight, 120 parts by weight of fine aggregate, 1.0 part by weight of a high-performance AE water reducing agent (solid content with respect to cement), and 22 parts by weight of water were charged into a twin-screw mixer and kneaded. The flow value of the formulation
In the method described in "JIS R 5201 (Physical test method for cement) 11. Flow test", the measurement was carried out without performing the falling motion 15 times. As a result, the flow value was 270 mm. Further, the composition was poured into a mold of φ50 × 100 mm, placed at 20 ° C. for 48 hours, and then steam-cured at 90 ° C. for 48 hours.
The compressive strength (average value of three strands) of the cured product was 210 MPa. Further, the composition was poured into a mold of 10 × 10 × 40 cm, placed at 20 ° C. for 48 hours, and then steam-cured at 90 ° C. for 48 hours.
The bending strength (average value of three pieces) of the cured product was 25 MPa. Further, the composition was poured into a mold having a size of 10 × 10 × 40 cm, placed at 20 ° C. for 48 hours, and then steam-cured at 90 ° C. for 48 hours.
Then, after cooling to 20 ° C., the mold was removed. The specimen was heated at 20 ° C.
It was stored at a humidity of 60% for 91 days, and the amount of drying shrinkage from the time of demolding was determined. The amount of drying shrinkage of the cured product (average value of three) is 50 μm
Met.

Example 2 100 parts by weight of low heat Portland cement, silica fume 3
2.5 parts by weight, fine aggregate 120 parts by weight, high-performance AE water reducing agent 1.0 part by weight (solid content with respect to cement), water 22 parts by weight, steel fiber
(2% of the volume in the formulation) was charged into a twin-screw kneading mixer and kneaded. The flow value of the formulation was measured as in Example 1. As a result, the flow value was 250 mm. Further, the compression strength and the bending strength were measured in the same manner as in Example 1. As a result, the compressive strength was 210 MPa and the bending strength was 47 MPa. Further, the amount of drying shrinkage was measured in the same manner as in Example 1. As a result, the drying shrinkage was 50 μm.

Example 3 100 parts by weight of low heat Portland cement, silica fume 3
2.5 parts by weight, fine aggregate 120 parts by weight, high-performance AE water reducing agent 1.0 part by weight (solid content with respect to cement), water 22 parts by weight, quartz powder
30 parts by weight, 24 parts by weight of wollastonite, and steel fiber (2% of the volume in the composition) were put into a twin-screw mixer and kneaded. The flow value of the formulation was measured as in Example 1.
As a result, the flow value was 250 mm. Further, the compression strength and the bending strength were measured in the same manner as in Example 1. As a result, the compression strength was 230 MPa and the bending strength was 47 MPa. Further, the amount of drying shrinkage was measured in the same manner as in Example 1. As a result, the drying shrinkage was 47 μm.

Example 4 Each material was charged into a twin-screw kneading mixer and kneaded so that the volume ratio of the mixture used in Example 3 and the coarse aggregate was 7: 3. The compression strength and bending strength of the composition were measured in the same manner as in Example 1. As a result, the compressive strength is 135 MPa and the bending strength is 13
MPa. Further, the amount of drying shrinkage was measured in the same manner as in Example 1. As a result, the drying shrinkage was 48 μm.

Example 5 Low heat Portland cement 100 parts by weight, silica fume 3
2.5 parts by weight, fine aggregate 180 parts by weight, high-performance AE water reducing agent 1.0 part by weight (solid content with respect to cement), water 22 parts by weight, quartz powder
30 parts by weight, 24 parts by weight of wollastonite, and steel fiber (2% of the volume in the composition) were put into a twin-screw mixer and kneaded. The mixture is put into a steel pipe (outer diameter 600 mm × length 10 m) (steel pipe thickness 9 mm) (the amount of concrete becomes 40 mm) and centrifugal molding (low speed 2 G × 2 minutes, low speed 5 G × 5 minutes, medium speed 15 G) × 5 minutes, high speed
35G x 15 minutes). No slag was found after centrifugal molding.

[0027]

As described above, since the steel pipe concrete pile of the present invention is manufactured using a compound having a compressive strength exceeding 130 MPa, the concrete thickness can be reduced, and the weight of the steel pipe concrete pile can be reduced. Is possible.
In addition, since the pile can be made thinner, it can be easily driven as a foundation pile. Furthermore, since the amount of drying shrinkage of the cured product of the composition of the present invention is extremely small, it is not necessary to use an expanding material in order to enhance the adhesion between the steel pipe and the concrete.

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Claims (7)

[Claims] 1. A steel pipe concrete pile, wherein the concrete portion is made of a hardened material of a compound containing at least cement, fine pozzolanic powder, fine aggregate having a particle size of 2 mm or less, a water reducing agent, and water. 2. The steel pipe concrete pile according to claim 1, wherein the composition contains metal fibers and / or organic fibers. 3. The metal fiber has a diameter of 0.01 to 1.0 mm and a length of 2 to 30.
The steel pipe concrete pile according to claim 2, which is a steel fiber of mm. 4. An organic fiber having a diameter of 0.005 to 1.0 mm and a length of 2
The steel pipe concrete pile according to claim 2, wherein the steel pipe concrete pile is at least one fiber selected from vinylon fiber, polypropylene fiber, polyethylene fiber, aramid fiber, and carbon fiber of up to 30 mm. 5. The steel pipe concrete pile according to claim 1, wherein the composition contains an inorganic powder having an average particle size of 3 to 20 μm. 6. The steel pipe concrete pile according to claim 1, wherein the composition contains fibrous particles or flaky particles having an average particle size of 1 mm or less. 7. The steel pipe concrete pile according to claim 1, wherein the composition contains coarse aggregate.