JPS61268406A - Manufacture of concrete molded shape through centrifugal-force molding method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for forming concrete using a centrifugal force forming method. It is designed to solidify and adhere to the inner wall surface of the concrete molded product by adding one or more additives selected from among the substances, so that no slurry is discharged.

<Conventional technology> When manufacturing concrete molded products using the centrifugal force forming method, when the concrete is compacted by centrifugal force, a slurry (also called slag) consisting of excess water and fine powder such as cement is used to form the concrete. It was oozing from the inside of the product tube. Conventionally, as a measure to deal with this discharged slurry.

l) Disposal; 2) Reduction and prevention of discharged slurry; and 3.
) Reuse of discharged slurry. In the case of 1), if the discharged slurry is disposed of as it is, it will cause environmental pollution and pollution, so the method is to collect the solid content by sedimentation and dispose of it, and neutralize the supernatant water before discharging it, or to filter the discharged slurry using a filter press. Methods such as disposing of waste in the form of cakes have been used, but these methods have problems such as requiring vast dumping sites and large amounts of money. In the case of 2), there is a method to prevent the discharged slurry from being reduced by adding fine powder etc. to the concrete material mixture in advance to increase water retention, but this method increases the amount of cement per unit, increases the unit water drainage, and shortens the curing time. There are problems such as increase in cost and difficulty in controlling product strength. Also, in recent years,
By adding a so-called cement setting accelerator,
A method for reducing the amount of slurry produced and the solids content in the slurry (JP-A-58-181108), or a setting accelerator used to solidify the solids in the slurry generated during centrifugal molding on the inner surface of concrete. and a surfactant for slurry processing under centrifugal force and for improving trowel finishing (Japanese Patent Application Laid-Open No. 58-180358
No. 3) have been proposed, but these still have the problem of requiring post-treatment and internal troweling treatment due to the generation of slurry. In addition, in the case of 3), there are many documents on the use of exhaust slurry, blast furnace slag, and flue gas desulfurization gypsum in concrete as binders, as well as partial replacement use in concrete, but most of them are at the research stage. However, since the water-cement ratio and slurry components of the slurry discharged during centrifugal molding vary greatly, it is extremely difficult to handle. Currently, of these measures, method 1) seems to be the majority.

(Problems to be Solved by the Invention) As described above, in the past, the slurry discharged during centrifugal compaction has been processed by a method that is problematic in that it involves complicated post-processing and costs. Therefore, there has been a strong desire for a method for manufacturing concrete molded products by centrifugal molding that does not have these problems.

In view of the above-mentioned problems, an object of the present invention is to provide a method for producing a concrete molded product using a centrifugal molding method, which can prevent discharged slurry from coming out and obtain a concrete molded product with excellent performance.

<Means for Solving the Problems> The configuration of the present invention for achieving the above-mentioned object is to provide a method for manufacturing a concrete molded product by rotating a formwork filled with concrete and compacting the conocrete by centrifugal force. An additive consisting of one or more selected from quick-setting agents and water-absorbing substances is added to the slurry generated in the molded product during or after centrifugal molding, and the slurry is applied to the inner wall surface of the concrete molded product. It is characterized by solidifying Φ to adhere.

Hereinafter, the configuration of the present invention will be explained in detail.

The mix of concrete to which the method of the present invention is applied may be the mix used for conventional centrifugal molding, such as a unit cement amount of 300 to 700 kg/rn', a unit water amount of 120 to 180 kg/m', Fine aggregate ratio 30-4
5%, water reducing agent 0.3-4.0% (relative to cement) Slump 2-20 using various admixtures as necessary
There is one with c+n. Further, the conditions for centrifugal molding are not particularly limited, and are under a so-called predetermined centrifugal force load, that is, a conventional normal centrifugal force load condition, for example, 2.0
A total of about 5 to 10 minutes at G to 40 G may be used.

The additive consisting of one or more of the quick-setting agent and the water-absorbing substance used in the present invention can be used within a few minutes, preferably for 1 to 2
It has the ability to solidify and adhere to the inner wall surface of concrete 1 and molded products within minutes. To further comment on these things, the quick-setting agent reacts with the cement components in the discharged slurry, rapidly producing a hardened product, and converting this slurry into
It solidifies and adheres to the inner wall surface of a concrete molded product within 2 minutes. On the other hand, the water-absorbing substance absorbs the water contained in the slurry and swells to some extent, eliminating the fluidity of the slurry. It also integrates with the cement composition in the slurry, which has a reduced water-to-cement ratio, and solidifies on the inner wall surface of the molded product.・It is something that is attached.

These curing agents and water-absorbing substances can be used as additives in any combination as appropriate.

Here, as the quick setting agent, 15 to 65% by weight of calcination gun or calcination rock, 15 to 65% by weight of alkali metal aluminate
-30% by weight, 10-30% alkali metal carbonate and 10-30% quicklime (trade name: T
-Ro, ck), water glass No. 1, No. 2, No. 3, silica lithium, baking bread, sodium aluminate, soda carbonate, jet cement, alumina cement, etc. Among these, T -Rock, Mizu Glass No. 1, No. 2, and No. 3 have high quick setting performance.

In addition, as water-absorbing substances, ultrafine silica powder, Ben I
- Night, diatomaceous earth, xonotlite, sepiolite, water-absorbing mica, wood flour, shirasu balloon, pulp, paper powder, etc. are used.

The amount of the additive consisting of one or more of these quick-setting agents and water-absorbing substances may be as long as it is necessary and sufficient to solidify and adhere the slurry produced during centrifugal molding within a desired time. It is appropriately selected depending on the type of binder and water-absorbing substance, the concrete composition, the quality of the slurry produced, the water-cement ratio, etc. In other words, if there is little slurry generation or if the water-cement ratio in the slurry is small,
By adding a small amount, it is possible to solidify and adhere more firmly. Naturally, it also varies depending on the type of quick-setting agent and water-absorbing substance used. In the case of a general concrete mix, the amount of slurry produced is approximately 3% by weight of the amount of concrete used, so the amount of additive added is determined by the amount of T-Rock in the quick-setting agent, as shown in the experimental example later. , lithium silicate, water glass No. 1, No. 2, or No. 3 is used, it is 0.1% by weight or more based on the amount of concrete used, preferably 0.2 to 0.
．． In the range of 5% by weight, 0.3 when using other quick-setting agents
It is at least 0.4% by weight, preferably from 0.4 to 0.6% by weight.

If the value is less than the lower limit of this range, sufficient effect will not be obtained.
Moreover, even if it is used beyond the upper limit of the preferable range, the increase in effect is small. Also, in the case of water-absorbing substances, the amount added varies greatly depending on the type.
In short, it reduces the fluidity of the slurry, integrates with the cement composition in the slurry, and solidifies and forms on the inner wall surface of the molded product.
Just use the amount that will be deposited.

In addition to these quick-setting agents and water-absorbing substances, water in ordinary Portland cement, early strength Portland cement, ultra early strength Portland cement, moderate heat Portland cement, sulfate-resistant cement, blast furnace cement, fly ash cement, silica cement, etc. Hard cement and ALC
Inorganic powders such as powder, clay powder, and silica powder may be used in combination.

The timing of adding the additive is not particularly limited, and may be added during or after centrifugal molding. If it is added after centrifugal molding under the above-mentioned molding conditions, it is necessary to further rotate under the same conditions or at a somewhat slower speed of about 2 to IOG. In this case, the smaller the centrifugal force load is, the more economical it is, but if it is smaller than 2G, it becomes difficult to uniformly disperse the additive, which is not preferable. The additive may be dispersed or sprayed in powder or liquid form for 5 to eO seconds.

As explained above, in the molded product to which this method is applied, the slurry generated during centrifugal force molding is uniformly distributed, solidified, and adhered to the inner surface of the molded product.

Therefore, the slurry is not discharged after centrifugal molding.
The slurry treatment step after molding, which was essential in conventional centrifugal molding, is eliminated.

The centrifugally molded product then undergoes a normal curing process to become the final product. That is, if necessary, atmospheric pressure steam curing at a temperature of about 65°C and/or 180°C
The final product is cured in an autoclave at a high temperature and pressure of about 000 atmospheric pressure. In this way, the final product obtained has the slurry fixed uniformly on the inner surface, and cracks are also seen in the fixed slurry layer, which is equivalent to the concrete product obtained by the conventional centrifugal forming method. It has the above performance. In addition, since the generated slurry is uniformly distributed and solidified on the inner surface of the product, there is no need to consider deformation or eccentricity of the product during movement during the manufacturing process, product transportation and stocking process, and handling can be the same as conventional products.

Note that the method of the present invention can be applied to the production of all concrete products that are formed using centrifugal force. For example, RC<
Yes, PC < Yes, Post tension PC < Yes, High strength PC
It can be suitably used for manufacturing composite stakes such as steel pipes, and poles such as PC balls and colored balls.

The present invention will be explained in more detail below along with experimental examples and examples.

<Experimental Examples> Experimental Example 1 Eight types of rapid setting agents were added and mixed to 125 g of slurry with a water-cement ratio of 1.5, and the coagulation properties were tested. Measure the time until the solidified contents do not move even if the container is tilted, and
It was determined that the time was within 0.18 to 30 seconds, 0.131 to 60 seconds Δ, and 61 seconds or more ×. The results are shown in Table-1. In addition, the ratio to concrete (%) is 3% of the concrete weight.
It is assumed that a slurry equivalent to

Margin table below - 1 *1) Product name: Manufactured by Onoda Semen L', a quick-setting agent whose main ingredient is a calcination block or a calcination block stone.

As shown in Table 1, in this experiment, T-lock, water glass No. 1, No. 2, No. 3, and lithium silicate solidified within 1 minute if 0.1% by weight or more was added to concrete. , it can be seen that these exhibit excellent rapid setting properties for slurry. (1) In the case of other quick-setting agents, if 0.3% by weight or more is added, solidification can be achieved within 1 minute.

Experimental Example 2 Various water-absorbing substances were added and mixed to 125 g of slurry with a water-cement ratio of 1.5. Here, O indicates that the sample no longer flows out even if the container is tilted.

Table 2 (Example) Example 1 Crushed stone from Iwase, Ibaraki Prefecture with a maximum size of 20 mm was used as the coarse aggregate, and river sand from Ogasa, Shizuoka Prefecture with a maximum size of 5 cm was used as the fine aggregate.
Cement weight 480kg/rri2, water amount 1301, g/
Sample concrete (slump 188 layers) was prepared by mixing 1.6% of the water reducing agent Mychy 150 (trade name, Kao Soap ■) with respect to the weight of cement. 15 kg of this fresh concrete is 20φ×30c+
s into a centrifugal molding mold, compacted at 2.5G to 34G for 7 minutes, and then placed 25cc of water glass No. 3 (manufactured by Nippon Kagaku Kogyo Co., Ltd.) in the mold rotating at 5G. with water
A diluted solution of :1 was sprayed for 20 seconds and rotated for 45 seconds. There was no residual slurry in the obtained centrifugal compact, and the slurry was uniformly solidified on the inner surface. This molded body was cured in an autoclave (heated at 30°C/hour, 180°C, 10
(maintained at atmospheric pressure for 5 hours). The compressive strength of the obtained product is l
1143 kg/cm".

For reference, the fresh concrete was molded and compacted under the same conditions, the resulting slurry was discharged, and then cured in the same manner to obtain a molded body. The compressive strength of the molded article according to this prior art was 927 kg/cm'.

Example 2 After forming and compacting the ready-mixed concrete prepared in Example 1 under the same conditions, a rapid setting agent mainly composed of calcining rock was placed in a form rotating at 3G. T = Rock (
30 g of Onoda Cement (trade name) was added and rotated for 1 minute. This molded body was dried under the same conditions as in Example 1.
・The product obtained by crepe curing has a compressive strength of 951 kg/
crn', and no peeling of a layer of slurry uniformly formed on the inner surface of the strength test diameter was observed.

Example 3 Fresh concrete prepared in Example 1) 15 kg was 20φ
It was put into a centrifugal molding frame of cm x 30cm, and during centrifugal molding, it was heated at high speed with a diameter of 1 minute.
45 g of an additive consisting of 25% lye and 65% lye was added, and the mold was stopped at the specified centrifugal molding time. The obtained centrifugally molded product had no residual slurry at all, and the slurry, along with the additive, was solidified and adhered to the inner wall surface of the molded product. Furthermore, when this molded product was cured in the same manner as in Example 1, its strength was the same as that without additives.
Not a single layer of slurry was observed to peel off.

Example 4 The same procedure as in Example 3 was carried out except that 45 g of an additive consisting of 10% T-Rock, 15X paper powder, 75% paper powder, and 75% was used. As a result, there was no residual slurry inside the molded product. Furthermore, when this molded product was cured in the same manner as in Example 1, the strength was the same as that without additives.
Not a single layer of slurry was observed to peel off.

Example 5 The same procedure as in Example 3 was carried out except that 40 g of an additive consisting of 25% T-Rock and 75 pieces of Zonotlite was used, and there was no residual slurry inside the molded product.

In addition, when this molded product was cured in the same manner as in Example 1,
The strength was the same as that without additives, and no peeling of the slurry layer was observed.

<Effects of the Invention> According to the method of the present invention, the slurry generated during the centrifugal force forming process can be solidified and adhered to the inner surface of the product. The treatment or disposal process and its costs can be reduced, and the problems of environmental pollution and pollution can be solved. Furthermore, since the generated slurry is uniformly solidified and adhered to the inner wall surface of the concrete molded product, there is no need to consider deformation or eccentricity of the product during movement during the manufacturing process and during the process of transporting and stocking the product.

Claims (1)

[Claims] In a method of obtaining a concrete molded product by rotating a formwork filled with concrete and compacting the concrete by centrifugal force, the slurry generated in the concrete molded product contains an accelerating agent and a water-absorbing substance powder selected from the group consisting of: A method for producing a concrete molded product by a centrifugal force forming method, characterized in that one or more additives are added during or after centrifugal molding, and the slurry is solidified and adhered to the inner wall surface of the concrete molded product. .