JPS62265156A - Manufacture of pile pole - 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 producing piles and poles of excellent quality, and more specifically, the present invention relates to a method for producing piles and poles of excellent quality. Or mix concrete using cement slurry whose main component is a mixture of unpulverized cement.

This relates to a method for manufacturing piles and poles that shortens the steam curing time among centrifugal molding, steam curing, and autoclave curing methods, and has many advantages such as no slag generation, increased strength, and increased manufacturing cycle. have.

[Prior Art] In the production of secondary concrete products such as piles and poles, so-called high-performance dispersants are generally used as additives, but the cement slurry itself has not been subjected to any kind of treatment until now. It wasn't given much consideration.

The present inventors have discovered that a cement slurry obtained by wet-pulverizing cement in the presence of a dispersant etc. provides concrete with extremely high strength (Japanese Patent Application No. 59-237
No. 592) was not considered for use in secondary products.

The biggest problem in manufacturing centrifugally molded products such as piles and poles is the disposal of slag. This waste liquid is squeezed out from the inside of the product and is contaminated with cement components, laitance, etc., and its disposal has been a huge problem for secondary product factories. As a countermeasure, (1) increase the amount of cement.

(2) Reduce slump.

(3) Add silica hume.

Although methods such as these have been proposed, these methods increase costs and reduce workability, and a complete solution cannot be expected.

Normally, a strength of 300 to 400 kg/cj is required to demold the formwork, and it takes several tens of hours to reach this value, but in order to increase the rotation rate of the formwork and increase productivity, Recently, a steam curing method has been commonly used to increase the temperature of concrete during curing to 60 to 70° C. to develop strength in a short period of time. According to this method, demolding is possible in 5 to 6 hours.

[Problem that the invention seeks to solve]

By steam curing and autoclave curing method, pile
When manufacturing poles, not only equipment costs are high but also energy costs are high, so low energy and high productivity is desired. For this reason, it is desired to increase the initial strength and relax the steam curing conditions, as well as the above-mentioned slag problem.

[Means for solving problems]

As a result of various studies to solve these problems, we found that by using a cement slurry containing pulverized cement alone or a mixture with unpulverized cement as the main component, we could not only eliminate the generation of slag, but also It has been found that even if concrete is steam-cured at a lower temperature and for a shorter time than conventional methods, the same or higher strength can be obtained.

The pulverized cement used in the present invention is commercially available cement that has been pulverized to a specific surface area of approximately twice or more by a wet method.
237592) is used. Cement/water slurry is ground into extremely fine particles by using a powerful grinder.

Since the reaction between cement and water proceeds on the particle surface, as pulverization progresses, the surface area increases, creating a state in which the hydration reaction can easily proceed. As pulverization progresses, the cohesive force of cement particles increases and the viscosity rapidly increases, so a cement dispersant is added to suppress this phenomenon.6 Also, gypsum is added to suppress agglomeration and increase initial strength. It is also effective. Pulverizers include ball mills, vibration mills, and high-speed impact crushers.

Jet mills, stirring mills, etc. can be used.

Stirred mills are preferred.

In the present invention, pulverized cement is used alone or mixed with unpulverized cement, powdered silica stone is added, and the mixture is mixed with fine aggregate and coarse aggregate in a conventional concrete mixer. This kneaded material is used to manufacture products by centrifugal molding, steam curing, and further autoclave curing, but gypsum can be added to increase the strength during mixing. The preferred addition rate is 1 to 5% (based on cement).

〔Example〕

The product name Niatorita manufactured by Mitsui Miike Kakoki ■ is used as a stirring mill, and Yamaba Kokusaku Pulp is used as a cement dispersant! ! Cement was pulverized using Sunflow PS manufactured by $i under the following conditions.

Grinding conditions: Water-cement ratio: 40%, Sunflow addition rate: 2%.

Dihydrate gypsum addition rate 2%, 200 rpm, 15 minutes.

Next, concrete mixing, centrifugal molding, steam curing, and autoclave curing were performed. Centrifugal molding.

The conditions for steam curing and autoclave curing are as follows, and the conditions for concrete cross-conducting are as shown in the table. (
(The fine aggregate ratio indicates the ratio of fine aggregate in the total aggregate, and the Sunflow addition ratio indicates the ratio to the total cement added at the time of cross-tracking.) Centrifugal forming conditions: 15.5 kg of concrete in a φ200!1 x 30 cI11 formwork.

After 15 minutes of water injection, apply 3G (180 rpm) for 2 minutes.
15G (410rpm) for 1 minute, 25G (5
30 rpm) for 25 minutes.

35G (630rpm) for 8 minutes.

Steam curing conditions: Preparation, 30°C, 2 hours, temperature increase at 20°C/hr, 75°C
.

Hold for 4 hours and cool naturally.

Autoclave curing: Raise the temperature at 25°C/hr and hold at 180°C for 4 hours.

The test results are shown in the table below.

〔Effect of the invention〕

From the results of the examples, the strength of the product after steam curing and autoclave curing increases with the same formulation according to the method of the present invention,
It can also be seen that it is possible to completely prevent the occurrence of slag. In addition to 2, for the same strength, the amount of cement can be reduced and the steam curing conditions can be relaxed, compared to conventional 1.
It was confirmed that instead of one cycle per day, two cycles per day became possible, and productivity was greatly improved.

Claims (1)

[Claims] 1 Using a cement slurry whose main component is pulverized cement alone or mixed with unpulverized cement,
A method for producing piles and poles, which is characterized by shortening the steam curing time when concrete is mixed, formed, steam-cured, demolded, and then autoclaved.