JPH078737B2 - Method of manufacturing centrifugal force molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a method for producing a centrifugal force molded body, more specifically, concrete piles, poles, piles such as steel pipe composite piles,
The present invention relates to a method for producing a Hume pipe such as a heme pipe or a steel pipe lining, and a centrifugal force molded body that can be molded by utilizing centrifugal force.

The concrete used in the present invention is a general term for mortar or concrete.

[Prior Art and its Problems] Conventionally, a high-performance water reducing agent has been indispensable for increasing the strength of concrete, and has been frequently used in the production of centrifugal force molded bodies.

However, the concrete to which the high-performance water reducing agent is added has poor tightness on the inner surface of the pipe in centrifugal molding. A large amount of glue is generated. Also, the drainage is poor. As a result, the strength of the tubular body is smaller than that of the normal vibration-compacted test piece, and when various admixtures are used together, part of them becomes slag and separates, so it was used sufficiently. High performance water reducing agents are not used except in special cases because the performance of the admixture is difficult to be exhibited, and in addition, fume pipes requiring an inner surface finish have poor moldability, so it is difficult to obtain the required strength. The problem is that the concrete mix is economical.

As a method for improving these problems, it has been proposed to add an organic acid such as an oxycarboxylic acid to a high-performance water reducing agent (Japanese Patent Publication No. 53-31888 and Japanese Patent Publication No. 59-69457).

However, the combination of high performance water reducing agent and organic acid alone,
Even if the water-cement ratio of concrete is 30%, the actual water-cement ratio of the tube after centrifugal force molding does not drop below 25%, the tube strength does not rise so much, and the organic acid strongly delays the setting and hardening. Since there is a function to do so, there are many variations in the strength of the concrete itself depending on the concrete temperature, curing before steam curing, that is, pre-curing time, etc.
In particular, there were problems such as large fluctuations in the strength of the test piece due to vibration compaction of 10φ x 20 cm for strength control, and this was not sufficient.

On the other hand, thiosulfate is well known as an inorganic compound of a setting hardening accelerator of cement together with sulfate, nitrate, nitrite and the like.

The inventors of the present invention, in improving the method for producing a centrifugal force molded product using a high-performance water-reducing agent and an organic acid in combination, among the above-mentioned setting and hardening accelerators, only thiosulfate has a high-performance water-reducing agent and an organic acid. Therefore, the inventors have found that the combined use of the above improves markedly the centrifugal force moldability and also the strength property, and thus completed the present invention.

[Means for solving problems]

That is, the present invention is characterized in that concrete is mixed with a cement admixture for centrifugal force molding containing a high-performance water reducing agent, organic acids, and thiosulfate as active ingredients, and centrifugal force molding is performed while dehydrating. This is a method for manufacturing a centrifugal force molded body.

Hereinafter, the present invention will be described in detail.

The high-performance water-reducing agent according to the present invention is a water-reducing agent that exhibits high dispersibility without excessive retardation of setting or air entrainment even when added in a relatively large amount, and is used in combination with thiosulfate. For the first time, the effect of the present invention can be obtained.

And, not to mention concrete not using a high-performance water reducing agent, even if a normal water reducing agent is used in combination with thiosulfate, no effect is seen.

According to the Japan Society of Civil Engineers Concrete Library No. 47 “Guideline for High-Strength Concrete Design and Construction (Draft)”, the high-performance water-reducing agent can be used as a high-performance water-reducing agent because of the chemical structure of its main components. Condensate system 2
They are roughly classified into types.

Here, those belonging to the polyalkylallyl sulfonate system are those containing naphthalene sulfonic acid or a derivative thereof, or a highly condensed formalin of a related substance as a main component, and specifically, a product name manufactured by Kao Soap Co., Ltd. "Mighty 10
"0", "Mighty 150", "Mighty HS", "Mighty 15"
0R "," Mighty 150RA ", Sanyo Kokusaku Pulp Co., Ltd. product names" Sunflow PS "and" Sunflow PSR ", Takemoto Yushi Co., Ltd. product name" Pole Fine 510N ", Nisso Master Builders product name" NL " -450 "and" NL-1440 "as well as the trade name" Cellflow 110P "manufactured by Dai-ichi Kogyo Kabushiki Kaisha can be used.

Further, those belonging to the highly condensed product system of the triazine derivative are
It is mainly composed of melamine formalin resin sulfonate. Specifically, trade name "Melment F-10" manufactured by Showa Denko KK and trade name "NL-4 manufactured by Nisso Master Builders" are used.
For example, "000" can be used.

Most of the commercially available products are those belonging to the polyalkylallyl sulfonate system, but in the present invention, both polyalkylallyl sulfonate system and highly condensed triazine derivative system can be used.

Details of these high-performance water reducing agents are published in "Cement / Concrete" No. 427 (1982) issued by Cement Association.

The use amount of the high-performance water reducing agent is preferably 0.2 to 5 parts by weight, and more preferably 0.4 to 3 parts by weight in terms of solid content, based on 100 parts by weight of cement, in view of economical efficiency and actually required strength properties. If it is less than 0.2 part by weight, the effect of improving centrifugal moldability is small, and if it exceeds 5 parts by weight, centrifugal moldability is deteriorated and improvement in physical properties is not expected so much.

The present invention is an improvement for further improving the centrifugal force formability of concrete using a high-performance water reducing agent and an organic acid in combination, and concrete not containing the high-performance water reducing agent, for example, lignin sulfonate system Even if thiosulfate is used in combination with concrete in which other general water reducing agents such as or polyol type are used in combination with organic acid, no effect can be obtained.

The organic acids according to the present invention are oxypolycarboxylic acids, oxymonocarboxylic acids, carboxylic acids, polycarboxylic acids and the like, or salts thereof.

Specifically, examples of the oxypolycarboxylic acid include malic acid, tartaric acid, and citric acid, and examples of the oxymonocarboxylic acid include heptonic acid, gluconic acid, glycolic acid, and the like. Further, as the carboxylic acid,
Oxidizing acids of saturated or unsaturated carboxylic acids, malonic acid, succinic acid, glutanoic acid, adipic acid, maleic acid, fumaric acid, and heptanoic acid, and the like.Polycarboxylic acids include acrylic acid and maleic anhydride. A cocondensate is mentioned.

And as these salts, oxypolycarboxylic acid, oxymonocarboxylic acid, and alkali metal salts of carboxylic acids, alkaline earth metal salts, and zinc, copper, lead,
And metal salts such as iron, and alkali metal salts or ammonium salts of polycarboxylic acids.

Commercially available products of polycarboxylic acid include "Work 500" manufactured by Nippon Zeon Co., Ltd. and "Aron 6001" manufactured by Toagosei Kagaku Kogyo Co., Ltd.

These organic acids are well known as setting hardening retarders for cement, and some are used as retarders for rapid hardening cement, but when these organic acids are added alone, strength hardening is completely expected. It cannot be done.

The amount of organic acids used is preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, and most preferably 0.01 to 0.2 parts by weight, based on 100 parts by weight of cement in concrete.
If it is more than 0.5 parts by weight, the strength effect tends to be small.

Examples of the thiosulfate according to the present invention include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as magnesium and calcium, and ammonium salt.

Usually, sodium, potassium, and ammonium salts are industrially produced, and the sodium salt is preferable from the economical viewpoint.

The amount of thiosulfate to be used is preferably 4 parts by weight or less, more preferably 0.003 to 2 parts by weight, based on 100 parts by weight of cement in concrete, calculated as an anhydride. If it exceeds 4 parts by weight, no slag is generated, but the dehydration property is poor and the compacted state is poor, and the mortar layer on the inner surface of the tube tends to be a soft state of about 1 to 2 cm.

As described above, by using the high-performance water-reducing agent, organic acids, and thiosulfate in combination, a centrifugal force molded body with a larger dehydration amount, a solid strength, and a higher strength than the conventional one can be obtained, and variations in strength etc. Reduced and stable strength is obtained.

Furthermore, silica fumes of ultrafine powder amorphous silica produced as a by-product from a ferrosilicon alloy furnace, and various admixtures such as fibers can be used together, and their performance can be sufficiently brought out.

In the practice of the present invention, thiosulfate, like high-performance water-reducing agents and organic acids, may be premixed with cement, or may be directly added to a mixer when kneading concrete,
It may be dissolved in a part of the kneading water or in a liquid superplasticizer, and the method is not particularly limited.

Also, centrifugal force molding is not a problem because it is a commonly used method,
It is not particularly limited.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 Using the concrete mix No. I shown in Table-1, the types and addition amounts of thiosulfates and organic acids were changed as shown in Table-2,
Centrifugal molding was performed at room temperature of 20 ° C.

Centrifugal force molding is performed with a 20φ x 30L x 5tcm test tube, the concrete amount is fixed at 17kg, and after centrifugal force molding, the amount of dehydration and the thickness of the soft inner mortar layer without tightening (hereinafter referred to as mortar thickness) Was measured, and the water-cement ratio after molding was calculated from the dehydration amount.

Centrifugal molding takes 5 minutes at low speed 6G, 5 minutes at medium speed 20G, high speed 3
3 minutes at 0G, 4 hours before molding, 70 ℃ for 3 hours
The temperature was raised up to and maintained for 3 hours to carry out steam curing.

After that, the mixture was naturally cooled, demolded the next day, and allowed to stand in the room for 6 days, and the compressive strength on the 7th day was measured.

The amount of thiosulfate or organic acid added is parts by weight based on 100 parts by weight of cement. The results are also shown in Table-2.

<Materials used> Cement: Denki Kagaku Kogyo Co., Ltd., ordinary Portland cement Sand: Niigata Prefecture Himekawa river sand, specific gravity 2.65 Crushed stone: 〃 Crushed stone, specific gravity 2.68 Water-reducing material e: High-performance water-reducing agent Cell Flow 110P "powder type thiosulfate α: sodium thiosulfate, anhydrous salt, 〃 β: potassium thiosulfate, 〃, 〃 γ: ammonium thiosulfate 〃, 〃 〃 δ: calcium thiosulfate, 〃, 〃 As is clear from Table 2, in the examples of the present invention, a centrifugal force molded body having a large dehydration amount and high strength can be manufactured as compared with the comparative examples in which organic acids are added alone.

Further, thiosulfate shows the effect of improving centrifugal moldability even when used alone, but when used in combination with an organic acid, dehydration is also improved and high strength is obtained.

Example 2 Using concrete mix Nos. II to VIII shown in Table-1,
Example 1 except that 0.5 and 0.1 parts by weight of sodium thiosulfate and citric acid were added to 100 parts by weight of cement, respectively, and the type and addition amount of the superplasticizer were changed as shown in Table 3. I went the same way. The results are also shown in Table-3.

The high-performance water reducing agent was added in terms of solid content, and the water content of the liquid high-performance water reducing agent was added to the kneading water.

Example 3 Using the concrete mix No. I shown in Table-1, potassium thiosulfate, sodium citrate, and high-strength cement admixture were respectively combined, and the room temperature was 13 ° C and the concrete temperature was 15 as shown in Table-4. As in Example 1, a test tube for centrifugal force molding and a test piece with a capless 10φ × 20 cm frame filled with vibration were prepared at a temperature of ℃, and the pre-positioning time was 4
The latter, the latter was 2, 4, 6, and 8 hours, was aged in the same manner as in Example 1 and the compressive strength on the 1st day of the age was measured.

With respect to the centrifugal force molding test tube, the mortar thickness and dehydration amount after molding were measured. The results are also shown in Table-4.

<Materials used> Admixture: High-strength cement admixture, product name "Nonclave" manufactured by Osaka Cement Co., main component type II anhydrous gypsum pulverized product As is clear from Table 4, the centrifugal force molding property is good in the organic acid alone system, but due to its retarding effect, the centrifugal force molding test tube strength is smaller than that of the examples of the present invention, and the vibration packed test piece is also placed in front. As the absolute strength varies depending on time, the performance of the high-strength cement admixture cannot be fully exhibited.

Further, according to the present invention, the centrifugal force moldability is exerted more than the organic acid alone system, the centrifugal force molding test tube and the vibration packed test piece also have high strength, and the variation of the strength due to the pre-introduction time is small.

〔The invention's effect〕

In summary, the dehydration amount can be further increased by using the method for producing a centrifugal force molded body of the present invention.

 The centrifugal force molded body can be made more solid.

 Stable high strength can be obtained.

And other effects.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C04B 24/26 E H 24/30 B

Claims (1)

[Claims] 1. A concrete admixture comprising a high-performance water-reducing agent, an organic acid, and a cement admixture for centrifugal force forming, which contains thiosulfate as an active ingredient, and performing centrifugal force forming while dehydrating. Method of manufacturing centrifugal force molded body