JP2001181005A - Concrete or filling steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a concrete having sufficient fluidity, capable of sufficiently filling various kinds of shapes of steel pipes, providing a hardened product having both of high strength and toughness, and suitable of filling the interior of the steel pipe. SOLUTION: This concrete consists of a formulate comprising at least a cement, a pozzolanic fine powder, fine aggregate, water and water reducing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete for filling a steel pipe in a steel pipe concrete structure used for a building or the like.

[0002]

2. Description of the Related Art A steel pipe concrete structure has attracted attention as a driving structure of a high-rise building or a large structure because of its excellent mechanical properties and design properties and its easy construction. In a steel pipe concrete structure, concrete bears a compressive stress acting in the axial direction, and a steel pipe bears a tensile stress in a circumferential direction generated when a compressive stress is exerted, so that a strong proof stress against external stress can be exhibited. The extent of the development is particularly affected by the mechanical properties of the concrete filled into the steel pipe, and the proof stress is improved by improving at least either the compressive strength or the toughness of the concrete. On the other hand, the properties of concrete suitable for filling steel pipes must have high fluidity during filling, excellent separation resistance, and almost no shrinkage or expansion after hardening.

[0003]

However, in the conventional concrete, concrete with good filling properties generally has low strength and toughness. For example, high-strength concrete and high-toughness concrete tend to have low fluidity. As a result, poor construction is likely to occur and formability is likely to decrease.
In general, in these concretes, the flowability can be improved by using a high-performance water reducing agent, but it is difficult to secure desired strength and / or toughness if high fluidity is to be imparted. Therefore, the present invention aims to create concrete suitable for filling steel pipes, which has sufficient fluidity and has both high strength (corresponding to compressive strength) and toughness (corresponding to bending strength) after hardening. It is an issue.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the concrete for filling steel pipes represented by the following (1) to (6) has been found to have an improved filling property into steel pipes. The present invention has been completed because it is particularly excellent and has high strength and toughness after filling and curing.

That is, the present invention provides (1) a concrete for filling steel pipes, characterized by comprising at least a compound containing cement, fine pozzolanic powder, fine aggregate, water and a water reducing agent. (2) The concrete for filling a steel pipe according to the above (1), wherein the composition contains one or more of metal fibers, organic fibers, and carbon fibers. (3) The concrete for filling a steel pipe according to (2), wherein the metal fiber is a steel fiber having a diameter of 0.01 to 1.0 mm and a length of 2 to 30 mm. (4)
Organic fiber, diameter 0.01 ~ 1.0mm, length 2 ~ 30m
m, which is one or more fibers selected from vinylon fiber, polypropylene fiber, polyethylene fiber, and aramid fiber. (5) The concrete for filling a steel pipe according to (2), wherein the carbon fiber has a diameter of 0.01 to 1.0 mm and a length of 2 to 30 mm. (6) The composition contains quartz powder having an average particle diameter of 3 to 20 μm.
The concrete for filling a steel pipe according to any of (5). (7) The concrete for filling steel pipes according to any of (1) to (6), wherein the composition contains needle-like particles and / or plate-like particles having an average particle size of 1 mm or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, cement used for concrete production is not particularly limited, and any cement can be used. Preferably, the shape of the steel pipe
The use of medium heat Portland cement or low heat Portland cement is recommended if a particularly high filling property is required due to its dimensions, and the use of early-strength Portland cement is recommended if particularly high early strength is required due to construction and application places. Is done.

The pozzolanic fine powder contained as a component in the concrete of the present invention includes silica fume, silica dust, fly ash, slag, volcanic ash, silica sol, precipitated silica and the like. In general, silica fume and silica dust are preferable because the average particle size is 1.0 μm or less, and there is no need to pulverize by pulverization.
A pozzolanic substance having a relatively large particle diameter is pulverized to adjust the average particle diameter to 1.0 μm or less.

[0008] By mixing the pozzolanic fine powder, the concrete is densified by the microfiller effect and the cement dispersing effect, and the compressive strength is improved. On the other hand, when the amount of pozzolanic fine powder added increases, the unit water volume increases.
The amount is preferably 5 to 50 parts by weight based on 00 parts by weight.

The concrete of the present invention contains fine aggregate as a constituent, and the fine aggregate preferably has a particle size of 2 mm or less. In this case, the particle size of the fine aggregate is 85% (weight)
It is a cumulative particle size, and thus may contain some aggregate exceeding 2 mm in particle size. When the amount of fine aggregate having a particle size of 2 mm or less with respect to the total aggregate amount is reduced, the strength is reduced. Therefore, the fine aggregate amount is preferably 50% by weight or more of the total aggregate amount.

As the fine aggregate, any one of river sand, land sand, sea sand, crushed sand and silica sand or a mixed sand of two or more kinds can be used. The amount of fine aggregate is determined based on workability and separation resistance of concrete, strength after hardening and resistance to cracks, etc.
It is preferably 50 to 250 parts by weight, more preferably 80 to 180 parts by weight, based on 100 parts by weight of cement.

The concrete of the present invention contains a high-performance water reducing agent or a high-performance AE water reducing agent as a component, and the high-performance water reducing agent or the high-performance AE water reducing agent includes lignin, naphthalenesulfonic acid, melamine, and the like. Any of the polycarboxylic acid-based components can be used. In particular, a polycarboxylic acid-based high-performance water reducing agent or a high-performance AE water reducing agent can be suitably used. The amount of the high-performance water reducing agent or the high-performance AE water reducing agent to be added is 0.5 to 3. 4 in terms of solid content with respect to the cement, depending on the fluidity and separation resistance of the concrete, the strength after hardening, and the cost. 0% by weight is preferred.

The water / cement ratio in the concrete of the present invention is preferably from 10 to 35% by weight in view of the fluidity and separation resistance of the concrete, the strength and durability of the cured product, and the like.
15-30% by weight is more preferred.

In the present invention, it is preferable to use a compound containing at least one of metal fibers, organic fibers, and carbon fibers from the viewpoint of increasing the bending strength of the cured product, and particularly improving the toughness. Examples of the metal fiber include a steel fiber and an amorphous fiber. However, it is particularly recommended because a steel fiber having a high strength is easily obtained and the cost is advantageous. The metal fiber has a diameter of 0.01 to 1.0 mm and a length of 2
Those having a thickness of up to 30 mm are preferred. If the diameter is less than 0.01 mm, it is easily cut by tension, and the diameter is 1.0 mm
If the amount exceeds the above range, the number of fibers contained in the concrete decreases with the same amount, and the strength and especially the toughness are remarkably reduced. The fiber length is 30m
If it exceeds m, fiber balls are liable to be produced during kneading, and if the fiber length is less than 2 mm, the adhesive strength to the matrix is reduced, so that the bending strength is reduced. The compounding amount is preferably an amount corresponding to less than 4% of the concrete volume after setting, more preferably an amount corresponding to less than 3.5%. If the blending amount is 4% or more, the fluidity tends to decrease, so it is necessary to increase the unit water amount, which results in coagulation and a decrease in strength, which is not preferable.

The organic fibers include vinylon fibers, polypropylene fibers, polyethylene fibers, and aramid fibers. The organic fibers and carbon fibers preferably have a shape and a diameter of 0.01 to 1.0 mm and a length of 2 to 30 mm. The compounding amount of the organic fibers and / or carbon fibers is preferably an amount corresponding to less than 10% of the concrete volume after setting, and more preferably an amount corresponding to less than 7%. If the blending amount is 10% or more, the fiber dispersibility decreases,
In addition, the fluidity of the concrete tends to decrease, which is not preferable.

The concrete of the present invention preferably contains quartz powder having an average particle size of 3 to 20 μm, more preferably 4 to 10 μm, from the viewpoint of increasing the packing density of the cured product. As the quartz powder, a powder mainly composed of silica may be used in addition to quartz which is a natural mineral source. The amount of the quartz powder is 50 parts with respect to 100 parts by weight of the cement.
It is preferably not more than 20 parts by weight, more preferably 20 to 35 parts by weight. If the amount is more than 50 parts by weight, the fluidity of the concrete is lowered and the strength after curing is lowered, which is not preferable.

Further, the concrete of the present invention preferably contains needle-like and / or plate-like particles having an average major axis diameter of 1 mm or less in order to enhance the toughness of the cured product. Examples of the acicular particles include those composed of natural or synthetic ores such as wollastonite, bauxite, and mullite, and examples of the plate-like particles include mica flake, talc flake, vercurite flake, and aluminum flake. Can be mentioned. The amount of the acicular and / or plate-like particles is preferably at most 35 parts by weight, more preferably 10 to 25 parts by weight, based on 100 parts by weight of cement. If the amount is more than 35 parts by weight, the fluidity of the concrete may be lowered or the curability may be lowered, which is not preferable. The shape and size of the acicular particles are preferably those having an acicularity, that is, a value of (major axis diameter / minor axis diameter) of 3 or more.

The concrete for filling steel pipes of the present invention may optionally contain components other than those described above, for example, coarse aggregates and other admixtures as required.

In producing the concrete, the order of mixing the components is not particularly limited. The kneading of the compound may be carried out by using any kneading machine generally used in concrete production, for example, using an oscillating mixer, a pan-type mixer, a biaxial kneading mixer, a tilting mixer and the like. be able to. Also, the method of filling the kneaded material into the steel pipe may be such that the kneaded material is poured so as to fill the upper end of the steel pipe.
Vibration and the like need not be applied unless the steel pipe has a rather complicated internal shape. The shape and dimensions of the fillable steel pipe are not limited. After filling, desirably sealed, about 3-4
By curing at normal temperature and pressure for a week, strong steel pipe concrete can be obtained.

[0019]

[Examples 1 to 4] Low heat Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) as cement A, silica fume having an average particle diameter of 0.7 μm as pozzolanic fine powder, and silica sand Nos. 4 and 5 as fine aggregate C No. 2: 1 weight ratio mixture, limestone crushed stone having a maximum particle diameter of 20 mm as coarse aggregate, steel fiber 0.2 mm in diameter and 15 mm in length as fiber E, 0.6 mm in diameter and 15 mm in length as fiber F Vinylon fiber, commercially available polycarboxylic acid-based AE water reducing agent as a high-performance AE water reducing agent, natural quartz powder having an average particle diameter of 7 μm as quartz powder, and long axis diameter / short axis diameter of 0.3 mm as long axis diameter as acicular particles = About 4 wollastonites and a material selected from water were collectively charged into a twin-screw kneading mixer so as to have the compounding amounts shown in Table 1, and kneaded. The kneaded material was poured into a cylindrical steel mold having an inner diameter of 10 cm and a height of 20 cm up to the upper end, sealed in the mold, and cured at room temperature and pressure for 28 days. JIS based on compressive strength and flexural strength of cured concrete after curing
It measured by the method according to R5201. The results are shown in Table 1. The quality of the flow characteristics of the kneaded material was determined by JSCE.
Evaluation was made by observing the state by a test according to F503-1990, and the quality of separation resistance was evaluated by observing the breathing state. The results are also shown in Table 1.

[0020]

[Table 1]

[Comparative Examples 1-2] Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) as cement B, limestone crushed sand having a maximum particle size of 5 mm as fine aggregate D, limestone crushed stone having a maximum particle size of 20 mm as coarse aggregate, A material selected from a commercially available polycarboxylic acid-based AE water reducing agent as a high-performance AE water reducing agent and water was collectively charged into a twin-screw kneading mixer so as to have a compounding amount shown in Table 1 and kneaded. The kneaded material has an inner diameter of 10
The resin was poured into a cylindrical steel mold having a height of 20 cm and a height of 20 cm, sealed in the mold, and cured at room temperature and pressure for 28 days.
The same properties were evaluated for the kneaded material and the cured concrete in the same manner as in the above example. The results are also shown in Table 1.

[0022]

The steel pipe-filled concrete of the present invention has excellent filling properties based on high fluidity and can exhibit high strength and toughness, so that the yield strength of the steel pipe concrete structure can be improved without impairing the workability. Can be. For this reason, in addition to being applicable to a super-high-rise building, etc., the cross section of the steel pipe can be reduced, so that the effective space of the building can be increased and the weight and weight of the building can be sufficiently contributed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C04B 16:06 C04B 16:06 B 14:38 14:38 A 14:06 14:06 Z 24:26) 24:26) E 103: 32 103: 32 111: 20 111: 20

Claims (7)

[Claims] 1. A concrete for filling steel pipes, which comprises at least a compound containing cement, fine pozzolanic powder, fine aggregate, water and a water reducing agent. 2. The concrete for filling steel pipes according to claim 1, wherein the blend contains one or more of metal fibers, organic fibers and carbon fibers. 3. The metal fiber has a diameter of 0.01 to 1.0 mm,
The concrete for filling a steel pipe according to claim 2, which is a steel fiber having a length of 2 to 30 mm. 4. An organic fiber having a diameter of 0.01 to 1.0 mm,
The concrete for filling steel pipes according to claim 2, which is at least one fiber selected from vinylon fiber, polypropylene fiber, polyethylene fiber, and aramid fiber having a length of 2 to 30 mm. 5. The carbon fiber has a diameter of 0.01 to 1.0 mm,
The concrete for filling a steel pipe according to claim 2, which has a length of 2 to 30 mm. 6. The concrete for filling steel pipes according to claim 1, wherein the composition contains quartz powder having an average particle size of 3 to 20 μm. 7. The concrete for filling steel pipes according to claim 1, wherein the blend contains needle-like particles and / or plate-like particles having an average particle size of 1 mm or less.