JPH069256A - Production of centrifugally molded material - Google Patents

Abstract

PURPOSE:To improve the strength by centrifugally molding a cement mixture material containing a high performance water-reducing admixture and a thiosulfate, subsequently carrying out precuring and atmospheric-pressure steam curing, compacting the inside surface of the pipe, preventing generation of slag and increasing the amount of dehydration. CONSTITUTION:To 100 pts.wt. cement, e.g. 0.2 to 5 pts.wt. high performance water-reducing admixture (a highly condensed material between a polyalkylallysulfonic acid salt and a triazine derivative) and, e.g. 0.001 to 4 pts.wt. thiosulfate are added and the resultant mixture is kneaded together with water so as to prepare ready mixed concrete. After centrifugal molding, the molded material is precured, e.g. for 1 to 4hr, then kept, e.g. at 40 to 100 deg.C for 2 to 6hr for atmospheric-pressure steam curing and subsequently allowed to cool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a centrifugal force molded body of concrete, more specifically, concrete piles, poles, piles such as steel pipe composite piles, fume pipes such as fume pipes and steel pipe linings, and In addition, the present invention relates to a method for manufacturing a centrifugal force molded body that can be molded by utilizing centrifugal force.

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

[0003]

2. Description of the Related Art Conventionally, piles, fume pipes and the like have been manufactured by subjecting concrete to centrifugal force forming or vibration centrifugal force forming.

[0004] Since centrifugal molded products such as piles require high strength of, for example, 500 kgf / cm ² or more or 800 kgf / cm ² or more, generally, a high-performance water reducing agent is used, for example,
Add a large amount of solid content of 0.65 to 1.0% by weight to cement to reduce the water-cement ratio, and if necessary, add gypsum or a high-strength admixture containing gypsum as a main component, silica fume, or expander. Each of them is used alone or in combination to prepare concrete, which is put into a formwork, and the rotational speed is gradually increased to low speed, medium speed, and high speed to perform centrifugal molding.

However, in the case of producing piles, there is a problem that a large amount of a high-performance water reducing agent is added, so that the mortar layer on the inner surface of the pipe is not tightened and a large amount of slag is easily generated.

That is, when centrifugal molding is performed, fine powder such as cement, cement admixture, and sand is easily squeezed out as slag with water, but slag is generated as the amount of the high performance water reducing agent is increased. The amount tends to increase and the tightness of the mortar layer on the inner surface of the pipe tends to deteriorate.

Further, since a large amount of various cement admixtures added in addition to the cement are contained in the mortar layer and noro on the inner surface of the pipe, their performance cannot be sufficiently exhibited by piles. Therefore, in anticipation of the amount of various cement admixtures that will be separated and become invalid, it will often be uneconomically used by adding about 20% by weight to the cement from the beginning. .

On the other hand, the processing of the generated slag has been developed into a pollution problem.

In addition, the concrete using the high-performance water reducing agent is poor in water drainage, and in the extreme case, the centrifugal force molded body using the water retains water within 1 to 2 cm from the inner surface of the pipe, and the water drains out. It becomes a staying layer without forming a porous layer, so that it is easy to form a so-called junker layer, so that strength is likely to be reduced.

According to the experiments conducted by the present inventor, if the high-performance water-reducing agent is 0.2% by weight with respect to the cement and the slump is 5 cm or less, the occurrence of slag is small. If the slump is 2 to 3% by weight and the slump is 5 to 10 cm, it cannot be compacted at all.
There is also an extreme case where the mortar part separated on the inner surface flows out of the tube after centrifugal force molding. It was also confirmed that even if the high-performance water reducing agent was 0.2% by weight, slump would cause slag if it was 5 cm or more.

On the other hand, the finish of the inner surface of the fume pipes is more important than the piles, and the quality of the moldability including the finish affects the molding time and the product yield, that is, the production efficiency. Therefore, apply new mortar at the end of finishing, or apply an inner surface peeling agent to prevent partial peeling of the mortar layer on the inner surface of the pipe after steam curing for about 30 to 40 minutes. It is the current situation that the pipes are produced.

In addition, in the production of fume pipes, when general water reducing agents are used, not limited to high-performance water reducing agents, compaction will be poor, so it is normal not to use them in principle, and the required strength is obtained. However, it is uneconomical to increase the unit cement amount. In particular, if high external pressure strength is to be obtained, such as JIS A 5303 type 2 pipes and National Hume Pipe Association standard 3 type pipes, using an expansive material, the unit cement amount will increase, Along with this, the amount of expandable material tends to increase.

For this reason, expansion cracks and thermal cracks occur, and it is impossible to constantly manufacture the type III pipe. Even though measures have been taken such as introducing reinforcing bars for the type II pipe, cracks are completely prevented. There was a problem such as not being able to do it.

Further, with the recent development of the propulsion method, a fume tube having a large axial force, which is the compressive strength in the axial direction, that is, a so-called propulsion tube is demanded, and the amount of the high performance water reducing agent used for piles is about half or less. Although various cement admixtures have come to be used together, the use of high-performance water-reducing agents deteriorates centrifugal force moldability as described above, resulting in longer pipe manufacturing time, poor product yield, and high cost. There were challenges.

An attempt to solve these problems is the vibration centrifugal force molding method.

In the vibrating centrifugal force molding method, a high-performance water reducing agent is added in a large amount of, for example, 2 to 4% by weight with respect to cement, and W /
This is a method in which C is reduced to 25% or less as much as possible, hard concrete with a slump of 0 cm is made, and centrifugal force and longitudinal vibration are combined. However, in this method, dehydration is difficult to occur in spite of no separation of Noro.

Originally, centrifugal force molding is to arrange the materials from the outer side to the inner side of the pipe in descending order of the particle size of each material in the concrete, so to speak, to separate the materials. Is lower than the vibration molded body, and
Since it is hard concrete, it is not easy to handle.

Further, as a technique for improving centrifugal force molding with the addition of a high-performance water-reducing agent, gypsum and alum, which is a sulfate, are mixed, and about 1.5% by weight is added to the cement, whereby the inner surface of the fume pipe is added. A method was proposed to prevent the floating of the mortar layer by the generated ethrin guide, but the problem of not being able to prevent the occurrence of slag and improving the drainage of water and improving the centrifugal force moldability remained.
(JP-A-54-161627).

On the other hand, thiosulfate is well known as an inorganic compound for promoting setting and hardening of cement together with various chlorides, nitrates, sulfates and the like.

As a result of various studies on the above-mentioned problems of the prior art, the present inventor has found that among the above-mentioned inorganic compounds that accelerate the setting and hardening of cement, only thiosulfate is used in combination with a superplasticizer. The present invention has been completed based on the knowledge that the force moldability can be improved.

[0021]

Means for Solving the Problems That is, according to the present invention, concrete is mixed with a cement admixture for centrifugal force molding containing a high-performance water reducing agent and a thiosulfate as an active ingredient, and after centrifugal force molding,
It is a method for producing a centrifugal force molded body of concrete, which comprises performing pre-curing and steam curing.

The present invention will be described in detail below.

The high-performance water reducing agent according to the present invention does not cause excessive setting delay or air entrainment action even when added in a relatively large amount,
It is a water-reducing agent exhibiting high dispersibility, and the effect of the present invention can be obtained only when used in combination with thiosulfate. In addition to concrete not using a high-performance water reducing agent, it is not effective to use an ordinary water-reducing agent and thiosulfate in combination, and the effect cannot be observed even if the high-performance water reducing agent is used alone.

The high-performance water reducing agent is a concrete library No. 47 “High-strength concrete design implementation guideline” issued by Japan Society of Civil Engineers.
According to the (draft), the chemical structure of the main component is roughly classified into two types, that is, a polyalkylallyl sulfonate type and a highly condensed type of a triazine derivative.

Here, those belonging to the polyalkylallyl sulfonate group are those whose main component is naphthalene sulfonic acid or its derivative, or a highly condensed product of formalin, which is a related substance. Specifically, specifically, Kao Soap Company Product name "Mighty 100", "Mighty 150", "Mighty HS", "Mighty"
150R "," Mighty 150RA ", Sanyo Kokusaku Pulp Co., Ltd. product names" Sunflow PS "and" Sunflow PSR ", Takemoto Yushi Co. 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 system of triazine derivatives are those containing melamine formalin resin sulfonate as a main component, and specifically, trade name "Melment F-10" manufactured by Showa Denko KK and The product name “NL-4000” manufactured by Nisso Master Builders, Inc. can be used.

As the commercial products, those belonging to the polyalkylallyl sulfonate type are mainly used, but in the present invention, both polyalkylallyl sulfonate type and highly condensed triazine derivative type can be used. . Details of these high-performance water reducing agents are published in "Cement and Concrete" No. 427 (1982) issued by Cement Association.

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

The thiosulfate used in the present invention is Na
Examples thereof include alkali metal salts such as K and K, alkaline earth metal salts such as Mg and Ca, and ammonium salts. Usually, industrially produced salts of Na, K and ammonium, Na salt is most preferred from the economical viewpoint.

The amount of thiosulfate used is preferably 5 parts by weight or less, based on 100 parts by weight of cement, calculated as an anhydride, and 0.0
01 to 4 parts by weight is more preferable, and 0.003 to 2 parts by weight is the most preferable. When it exceeds 5 parts by weight, the occurrence of slag is small, but
The dehydration is poor and the compacted state is poor, and the mortar layer on the inner surface of the pipe tends to be a soft state of about 1 to 2 cm.

The method of using the superplasticizer and thiosulfate according to the present invention in concrete is not particularly limited, and even if the concrete is mixed after mixing with cement, it is added when kneading concrete with a mixer. Good. It is also possible to dissolve it in kneading water in advance.

In the present invention, in addition to the superplasticizer and the thiosulfate, a gypsum or a high-strength admixture containing gypsum as a main component, silica fume, and an expansive material can be added to concrete. The combined use of chemical admixtures is effective, and their performance can be fully exhibited.

The concrete according to the present invention is poured into a formwork by a usual method and is subjected to a centrifugal force by a method which is carried out on site, for example, by accelerating the rotation speed in steps of low speed, medium speed and high speed. Molded or vibrated by centrifugal force.

In the present invention, the centrifugal force molded body is subjected to pre-curing after centrifugal force molding, and then to normal pressure steam curing. For example, after centrifugal molding, pre-curing for 1 to 4 hours, 40 to 100
It is possible to carry out curing by holding at 2 ° C. for 2 to 6 hours for steaming under normal pressure, and then naturally cooling.

[0035]

EXAMPLES The present invention will be further described below with reference to examples.

Example 1 Concrete was prepared using the concrete mix No. I shown in Table 1, and thiosulfate and a high-performance water reducing agent were added as shown in Table 2 to obtain 17 kg of concrete. Outside diameter 20c
A test tube of m, length 30 cm, and thickness 5 cm (shown as 20φ × 30 L × 5 cmt) was centrifugally molded. Centrifugal force molding conditions are 6G and 4
Minutes, 5 minutes at 20G, and 3 minutes at 30G. Then, the mixture was left for 4 hours, heated at room temperature for 2 hours and kept at 65 ° C. for 4 hours under normal pressure steam curing, and then naturally cooled. The amount of dehydration during centrifugal force molding and the thickness of the mortar layer were measured, and the actual water-cement ratio after centrifugal force molding in consideration of the amount of dehydration was calculated from the following formula.

[0037]

[Equation 1]

Also, make a vibration molded body of 10φ × 20 cmL,
It was aged in the same manner as the centrifugal force-molded body, demolded the next day, and the compression strength after 24 hours was compared. The results are also shown in Table 2.

<Materials used> Cement: ordinary Portland cement, manufactured by Denki Kagaku Kogyo Fine aggregate: Himekawa river sand, specific gravity 2.65 Coarse aggregate: Himekawa crushed stone, specific gravity 2.68 Thiosulfate A: sodium thiosulfate anhydrous, industrial Thiosulfate B: calcium thiosulfate anhydrous, reagent thiosulfate C: potassium thiosulfate anhydrous, industrial thiosulfate D: ammonium thiosulfate anhydrous, industrial thiosulfate E: lithium thiosulfate anhydrous, reagent Water reducing agent F: High performance water reducing agent, product name "Mighty 100" powder manufactured by Kao Soap Company

[0040]

[Table 1]

[0041]

[Table 2]

As is apparent from the table, by using the method for producing a centrifugal force molded body of the present invention, compaction of the molded body is improved, the dehydration amount during molding is large, and the strength is higher than that of the vibration molded body. It is clear that the effect is large, and there is no great difference in the effect depending on the type of thiosulfate, and even if a small amount of thiosulfate is added, the effect is extremely large. The optimum amount of thiosulfate added is 100 parts by weight of cement,
It is 0.003 to 2 parts by weight.

Example 2 Concrete mix Nos. II to X shown in Table 1 were used, and 0.1 parts by weight of sodium thiosulfate was constantly added to 100 parts by weight of cement to prepare concretes.
The same procedure as in Example 1 was carried out except that the kind and addition amount of the superplasticizer were changed as shown in FIG. A liquid high-performance water reducing agent was added in terms of solid content, and water was used as a part of kneading water. Because the slump varies slightly depending on the brand of high-performance water reducing agent,
The slump was kept constant by adjusting the amount of water. In addition, in order to improve the water reduction rate = (unit water amount of plain concrete-unit water amount of concrete using water reducing agent) x 100 / unit water amount of plain concrete) for the concrete of the same slump, compound No. IX is 24.0 kg / m ³ , Formula No. X is 38.4k
Silica fume of g / m ³ was used. The results are also shown in Table 3.

<Materials used> Silica fume: By-product in ferrosilicon production, 0.1
μ High-performance water-reducing agent G: trade name “Cell Flow 1” manufactured by Daiichi Kogyo Yakuhin
10P ", powder High-performance water reducing agent H: Showa Denko's trade name" Melment F-1 "
0 ”, powder High-performance water reducing agent I: Kao Soap Co., Ltd. product name“ Mighty 150 ”solid content conversion High-performance water reducing agent J: Kao Soap Co. product name“ Mighty 150R ”solid content conversion High-performance water reducing agent K: Kao Soap product Product name “Mighty HS” solid content conversion high-performance water reducing agent L: Sanyo Kokusaku Pulp Co., Ltd. product name “Sunflow PS” solid content conversion high-performance water reducing agent M: Sanyo Kokusaku Pulp Co., product name “Sunflow PSR” Solid content conversion high-performance water reducing agent N: Trade name "Pole Fine 5" manufactured by Takemoto Yushi Co., Ltd.
10N "solid content conversion high-performance water reducing agent O: Nisso Master Builders' product name" NL-1450 "solids conversion high-performance water reducing agent P: Nisso Master Builders product name" NL-4000 "solids conversion other Is the same as that used in Example 1.

[0045]

[Table 3]

As is apparent from the table, by using the method for producing a centrifugal force molded body of the present invention, compaction of the molded body is improved, the dehydration amount during molding is large, and the strength is higher than that of the vibration molded body. It is clear that a large amount of the high-performance water-reducing agent exhibits a large effect, and the most practically or economically preferable amount is 0.2 parts with respect to 100 parts by weight of cement.
~ 5 parts by weight.

Example 3 In Example No. 2-6 of Example 2, the same procedure as in Example 2 was carried out except that 0.003 parts by weight and 0.01 parts by weight of sodium thiosulfate were added to 100 parts by weight of cement. . The results are shown in Table 4.

[0048]

[Table 4]

As is clear from the table, by using the method for producing a centrifugal force molded body of the present invention, compaction of the molded body is improved, the amount of dehydration during molding is large, and the strength is higher than that of the vibration molded body. Is large.

Example 4 Ingredient Nos. XI to XII of concrete shown in Table 1 and an expansion material of 60 k were used.
Compounding g / m ³ , compounding No. XII is a high performance water reducing agent I
Is 0.7 parts by weight, compound No. XIII is 0.7 parts by weight of the high-performance water reducing agent I and 0.1 parts by weight of thiosulfate C, and is an actual fume tube of JIS type 2 pipe, inner diameter 60 cm, length 243 cm, thickness An actual machine of 5 cm was manufactured. Reinforcement ratio of spiral is 0.86%, pitch 45
mm, straight reinforcement ratio is 0.23%, and the thickness of each spiral and straight reinforcement is 5 cmφ. Centrifugal molding was carried out by the usual method, and steam curing and water spray curing were performed. An external pressure strength test and a compressive strength test of the core of an actual pipe were conducted on the 14th day of the material. In the compression test of the core, a 30 cmφ core is extracted from the fume tube, and a sample with a width of 10 cm, a length of 20 cm, and a thickness of 5 cm is cut out so that the tube axis direction is the compression direction, and the eccentric load is obviously excluded. Then, the test was performed at n = 5. The results are shown in Table 5.

<Materials used> Expansion material: Product name “Denka CSA # 20” manufactured by Denki Kagaku Kogyo Co., Ltd. Other materials used in Example 1 or 2 are used.

[0052]

[Table 5]

As is clear from the table, the fume tube molded by the method for producing a centrifugal force molded body of the present invention has a larger dehydration amount than the comparative example, and even in the compacted state, there is no mark even if it is pressed with a finger. It can be seen that it is possible to obtain the one that is tightly tightened, the tube strength is large, and the external pressure strength is about 1 t / m larger than the standard value.

Example 5 Using concrete mix Nos. XIV to XVII shown in Table 1,
The admixtures are 47 kg / m ³ for compound Nos. XIV to XVI, and compound No. XVII for compound No. XVII.
45kg / m ^{3 is} compounded, and compound No. XIV is a high performance water reducing agent N
Was mixed with 0.1 parts by weight of thiosulfate D for the compound Nos. XV to XVII to produce RC pile of 30φ × 300 L × 6 cmt. Eight 12 mmφ PC steel rods were used, and 5 mmφ iron wire was used as a spiral bar at a pitch of 50 mm. Centrifugal molding and steam curing were performed by the usual method, and the mold was removed the next day. At the time of centrifugal molding, both ends of the pile were capped to prevent slag and dewatered water from leaking, and the amount of dewatering, the state of slag, and the pipe-making state were observed during demolding. Also, from this RC pile, 30φ x 100cmL
Two specimens of No. 3 were cut out, the cut surface was capped with cement paste, and the strength on the 3rd day of age was measured. further,
Vibration-molded concrete of the same composition, 10φ x 20 cmL
A test piece was prepared, cured the same, and similarly measured for strength. The results are shown in Table 6. In addition, compound No.XIV is 800kgf / cm
It is a general formulation in the production of high strength piles of ² or more.

<Materials used> Admixture: Denka Chemical Co., Ltd. trade name “Denka Σ1000” main component gypsum Others are the same as in Example 1 or Example 2.

[0056]

[Table 6]

As is clear from the table, the concrete pile molded by the method for producing a centrifugal force molded body of the present invention has a larger dehydration amount than that of the comparative example, its strength is higher than that of the vibration molded body, and the slump The effect is exerted regardless of the degree, and it can be carried out with an economical composition.

Example 6 Using concrete mix Nos. XVIII to XX shown in Table 1,
40kg / m ^{3 of} admixture, 3 parts by weight of high-performance water reducing agent G,
Furthermore, compound No.IXX and compound No.XX contain thiosulfate A at 0.2
By blending parts by weight, vibrating centrifugal force molding method, inner diameter 60 cm, length 24 c
A fume tube of m and 6 cm thick was made. Reinforcing bars were the same as in Example 4, first, concrete was added while rotating the form at a low speed of about 5 G, and then medium speed rotation of about 25 G was performed, and at the same time, a vibration width of 4 mm and a longitudinal vibration of 2700 vibrations / min. 90 seconds was added, and then centrifugal force molding was performed at 40 G rotation. Age 28
The internal pressure test by water pressure was conducted every day, and the maximum value and the maximum water pressure were measured when the water pressure did not rise because the pipe was broken or cracked due to water pressure. Further, using a concrete of the same composition, a test piece of 10φ × 20 cmL was vibration-molded, and the compressive strength on the 28th day after the same curing was measured. The results are shown in Table 7.

<Materials Used> Admixture: Osaka Cement Co., Ltd., trade name “NONCLAVE”, Main ingredient type II anhydrous gypsum Others are the same as in Example 1 or Example 2.

[0060]

[Table 7]

As is apparent from the table, the maximum fume pressure of the fume tube molded by the method of manufacturing a centrifugal force molding of the present invention is higher than that of the comparative example. This is considered to be because the comparative example was not dehydrated at all during pipe making, while the fume tube of Example had a large amount of dehydration and improved strength.

[0062]

INDUSTRIAL APPLICABILITY As described above, by using the method for manufacturing a centrifugal force molded body of the present invention, 1. The mortar layer on the inner surface of the pipe can be compacted to reduce or prevent the occurrence of slag, and the performance of the cement admixture can be fully exhibited. 2. Increase the amount of dehydration, promote the solidification of the centrifugal force molded body,
The strength can be improved. 3. Regardless of the amount of high-performance water reducing agent or the size of the slump, centrifugal moldability is improved, and the unit cement amount or cement admixture amount is reduced by using the high-performance water reducing agent for fume pipes, etc., and economic efficiency is achieved. be able to. 4. Also in vibration centrifugal force molding, dehydration is promoted, strength is improved, soft concrete can be sufficiently molded, and physical properties are not deteriorated. And so on.

Claims (1)

[Claims] 1. A concrete admixture comprising a high-performance water reducing agent and a cement admixture for centrifugal force molding containing a thiosulfate as an active ingredient, and after centrifugal force molding, pre-curing and normal-pressure steam curing are performed. Method for manufacturing centrifugal force molded body of concrete.