JP3222040B2 - Mixing method of concrete for centrifugal force forming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile, a steel pipe composite pile, and a concrete using sludge reducing material.
The present invention relates to a method of mixing concrete for producing a centrifugal force molded product of a pole, a fume pipe, and a steel pipe-concrete, and more particularly to a method of mixing concrete for centrifugal force forming which improves workability and compressive strength.

[0002]

2. Description of the Related Art Conventionally, a concrete pile manufactured by centrifugal force molding generates sludge by centrifugal force at the time of manufacturing. This sludge contains 20 to 40% by weight of fine powder such as cement and sand, and is strongly alkaline. Therefore, it cannot be disposed of outside the factory as it is for preventing pollution. The supernatant is neutralized and drained, and the sediment is discarded as industrial waste.In recent years, however, it is difficult to discard it as industrial waste due to the tightening of various regulations. It has become. In order to reduce the generation of this sludge, the present inventors have proposed a slag reducing material containing bentonite as a main component, a centrifugal force molded article using the same, and a method for producing the same (Japanese Patent Laid-Open No. 3-247543). Such) . JP-A-59-215808 also proposes a method for producing a concrete column for reducing sludge using silica fume, and further includes a method of adding a flocculant such as polyacrylamide (JP-A-51-215808). JP-A-68621), and a method using ultra-fine powder such as fly ash fume, iron hydroxide and the like. And it is marketed as a partly admixture.

[0003] However, concrete containing an admixture for reducing the generation of sludge is in a plastic state having a strong water retention capacity, or is a concrete having an extremely viscous property. When concrete with a small slump is incorporated, it is difficult to work through a reinforcing bar and workability is remarkably poor. In addition, since the slump becomes large when pumping or the like, the unit water volume increases, and especially in piles etc., the control strength is 900 kgf / cm ² or more. There were two problems that it was difficult to obtain high strength.

[0004] The present inventor has found that when manufacturing a centrifugal force molded body such as a concrete pile manufactured using concrete to which a sludge reducing material is added, concrete can be easily incorporated and concrete can be mixed to improve compressive strength. As a result of intensive research from the viewpoint of
The inventors have found that two problems can be solved by blending an appropriate amount of fine aggregate of 5 to 5 mm, and have completed the present invention.

[0005]

That is, the present invention relates to a method of manufacturing a centrifugally formed body using concrete containing a sludge reducing material, which is generally used in concrete.
2.5-5 more for fine aggregate and coarse aggregate used for cleats
This is a method for mixing concrete, characterized by mixing 50 to 500 kg / m ^{3 of} aggregates of mm.

Hereinafter, the present invention will be described in detail. The fine aggregate having a size of 2.5 to 5 mm in the present invention is an aggregate generally called No. 7 crushed stone or bill, and is used when backfilling a tunnel or rolling a roadbed under asphalt pavement. Aggregate. Usually, fine aggregate (sand) and coarse aggregate (crushed stone, gravel) used for concrete are prepared to be within the standard particle size range prescribed by the civil engineering and architectural society so that they can be packed closely, or Those which do not greatly deviate from the range are used, and in the present invention, 2.
A fine aggregate of 5 to 5 mm is blended.

The aggregate of the present invention in the range of 2.5 to 5 mm is mixed at 50 to 500 kg / m ^{3 in} 1 m ³ of concrete. If the amount is less than 50 kg / m ³ , the workability when embedding concrete cannot be improved. If the amount exceeds 500 kg / m ³ , the strength is low even if a slump is prepared with a water reducing agent or the like so that the unit water amount does not increase. Is not preferred. Is preferably of from both viewpoints to 80~450kg / m ³ formulation, 100~400kg / m ³ and more preferably. When these are mixed with concrete, they may be replaced with coarse aggregates or may be arbitrarily mixed in consideration of the balance between fine aggregates and coarse aggregates.

[0008] The reason that the aggregate in the range of 2.5 to 5 mm improves workability is that the surface area of the whole coarse aggregate is increased by mixing such fine aggregate in an appropriate amount, and the aggregate is wrapped. Since the thickness of plastic or extraordinarily high viscosity mortar to which sludge reducing material is added is considered to be thin, it is thought that concrete will pop and fall apart when it hits the rebar, making it easier to pass through the rebar cage. Can be

The sludge reducing material in the present invention is an admixture that reduces or prevents the generation of sludge by resisting centrifugal force. As described above, a material containing bentonite or silica fume as a main component, or a mixture of these, Any of those containing a coagulant such as acrylamide as a main component, fly ash fume having a specific surface area similar to that of silica fume, iron hydroxide, and a polymer which dissolves in water and becomes fibrous can be used.

[0010] Bentonite is a general name of a clay mineral mainly composed of montmorillonite, and silica fume has a surface area of 150,000 generated from a ferrosilicon furnace or the like.
It is an ultra-fine powder mainly composed of amorphous SiO _{2 of up} to 3,000,000 cm ² / g. Fly ash fume is ash recovered from a pulverized coal-fired thermal power plant, which is further vaporized by high temperature and collected to have a surface area of 300,00.
Although it is an ultrafine powder of 0 to 700,000 cm ² / g, it is not limited to these as long as it has an effect of reducing or preventing sludge.

Commercial products include "Denka Plus Merit", a trade name of Denki Kagaku Kogyo Co., Ltd., "Asano NS", a trade name of Nippon Cement Co., Ltd., and "Onoda Slurry Rock", a trade name of Onoda Cement Co., Ltd. Any one of the above-mentioned components is used as a main component.

In addition, in the case of mixing concrete in the production of a centrifugal compact, the present invention uses a specific range of 2.5 to 5 mm of aggregate and sludge reducing material and commonly used fine aggregate and coarse aggregate. Other materials used may be those commonly used in the production of each type of centrifugal molded product. For example, as cement, various types of Portland cement, moderate heat, high strength, ultra high strength, admixture As high-strength admixture mainly composed of silica powder, blast furnace slag powder, fly ash and anhydrous gypsum, expanded material mainly composed of calcium sulfoaluminate or quicklime and magnesium oxide, and polyalkylallyl sulfone as water reducing agent High-performance water reducing agents such as acid salts, melamines, and polycarboxylates, and mixed water such as tap water and groundwater are used. .

[0013] In the present invention, concrete is also produced by kneading using a conventional mixer, and the method of putting concrete into a mold is also a conventional method of directly incorporating a concrete into a mold, a pump or a belt conveyor. Is adopted. Also, the centrifugal force forming method in the present invention may be a conventional method, and may be performed at a low speed (low speed I,
II), medium speed (medium speed I, medium speed II), and three to five stages using high speed.

[0014]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 As shown in Table 1, using a commercially available sludge reducing material,
As a method of judging workability of embedding, concrete having a varied amount of 2.5 to 5 mm of aggregate of various amounts of aggregate is mixed, and 15 kg of concrete is placed in a 10-liter plastic container, and the height of 1.5 m is determined. Then, it was dropped on a 40 mm mesh sieve, and the amount passed through the sieve was measured. In addition, to examine the degree of increase in compressive strength, a centrifugal force specimen having an outer diameter of 20 × length 30 × thickness 5 cm (n = 2) was prepared, and the compressive strength was measured 7 days after steam curing. did. The centrifugal force forming method is as follows.
Minutes, medium speed II was 3 minutes at 15G, and high speed was 5 minutes at 25G. Steam curing conditions: 4 hours in advance, 3 hours in temperature, 75 ° C
, And naturally cooled in a curing tank until the next day, and after demolding, cured in a room at 20 ° C. Table 2 shows the test results.

[0015]

[Table 1]

<Material used> Aggregate of 2.5 to 5 mm: No. 7 crushed stone, crushed stone from Himekawa basin, Niigata prefecture (specific gravity 2.64) Cement: Ordinary Portland cement (specific gravity 3.16) Sand: River sand from Himekawa basin, Niigata prefecture Specific gravity 2.6
2) Crushed stone: Crushed stone from the Himekawa basin, Niigata Prefecture (specific gravity 2.6)
4) High performance water reducing agent: β-NS type (specific gravity of stock solution 1.20) High strength admixture: Denka No. 10 manufactured by Denki Kagaku Kogyo Co., Ltd.
00 ", gypsum-based, specific gravity 2.85 Sludge preventive material: trade name" Plus Merit ", manufactured by Denki Kagaku Kogyo Co., Ltd., inorganic fine powder, specific gravity 2.27 water: tap water (specific gravity 1.00) water cement ratio: ( Water + high performance water reducing agent) / cement

[0017]

[Table 2]

<Measurement method> Slump value: compliant with JIS A1101 Compressive strength: compliant with JIS A1108

As shown in Table 2, the compression strength exceeds 900 kgf / cm ² by mixing 50 to 500 kg / m ³ of the fine aggregate of 2.5 to 5 mm according to the present invention.
-450 kg / m ³ is more preferable, and 100-400 k
It turns out that g / m ³ is more preferable. Further, peaking at While workability is judged to be the more the percentage passing through a 40mm mesh, weight passing larger the fine aggregate of 2.5~5mm is often indicated, 500 kg / m ³ or more Is shown. In any case, generation of sludge after centrifugal force forming was not recognized.

Example 2 Using the same materials as in Example 1, kneading the concrete mix for pumping shown in Table 3 to prepare a specimen similar to that of Example 1, and curing under the same curing conditions. Then, the compressive strength at the age of 7 days was measured. Table 4 shows the results. From Table 3, even in the case of pumping, 900% by mixing fine aggregate of 2.5 to 5 mm of 50 kg / m ³ or more as in the present invention.
It is shown to exceed kgf / cm ² . In each case, generation of sludge after centrifugal force forming was not observed.

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

As described above, in producing a centrifugal molded body using the concrete to which the sludge reducing material of the present invention is added, the concrete is used for ordinary concrete.
2.5 to 5 mm of aggregate to fine aggregate and coarse aggregate
By adding 0 to 500 kg / m ³ , the workability and the compressive strength of the centrifugal molded product can be improved.

Claims (1)

(57) [Claims] When producing a centrifugal force molded body using concrete to which a sludge reducing material is added, fine aggregate or coarse aggregate used for ordinary concrete in concrete is provided.
And further add 2.5 to 5 mm of aggregate to 50 to 500 kg / m ³
A method for blending concrete, characterized by blending.