JPH05154829A - Method for adjusting consistency - Google Patents

Abstract

PURPOSE:To rapidly adjust consistency on the spot by using a thickener composed of carboxy methyl cellulose in the adjustment of the consistency of concrete not hardened. CONSTITUTION:The concrete not hardened carried job the job site by an agitator truck is charged in a re-kneader and a thickener composed of carboxy methyl cellulose is added to the concrete to be mixed therewith under stirring. By this method, a proper consistency can be rapidly obtained only by adding an extremely small amount of the thickener without requiring a large amount of cement or fly ash.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the consistency of ready-mixed concrete, i.e., ready-mixed concrete, at a concrete pouring site. More specifically, it relates to a method of adjusting the fluidity and the softness of concrete according to the amount of water.

[0002]

2. Description of the Related Art The consistency of ready-mixed concrete is
It is well known that this is one of the most important requirements for concrete construction. By the way, if the consistency value is small, in other words, the slump value is small, and so-called hard-mixed concrete is used, the driving operation becomes difficult. On the other hand, when the concrete has a high consistency value and is well-mixed, the workability is improved, but there are drawbacks such as a decrease in strength and breathing.

That is, if the concrete has a high consistency and is a lightly kneaded concrete, the durability of the concrete is reduced when the mold is removed after hardening. On the other hand, if the concrete has a low consistency value and is hard-mixed, it takes time and effort to compact the concrete around the reinforcing bars and the corners of the mold, resulting in a decrease in the efficiency of the placing work and the pea board phenomenon. There are drawbacks such as occurrence of.

Particularly, in the slip-form construction method, that is, the sliding frame construction method, continuous construction of concrete barriers, circular waterways, bridge protection walls, etc., and watertightness such as U-shaped and L-shaped waterway concrete structures are required. The above tendency is remarkable when a concrete structure is manufactured. Therefore, proper adjustment of the consistency is a very important matter. For example, when placing a concrete barrier, if the consistency is hard, there will be many voids and the strength will be insufficient.If the consistency is soft, the prescribed height cannot be maintained and the crown will sink and the The part will swell. The so-called "who" is in a "flame" state.

By the way, as a means for adjusting the consistency, the following method has been conventionally used. In general, concrete does not use the on-site mixing method.
It is kneaded in a so-called concrete plant of the IS designated factory and brought to the site as redemixed concrete (hereinafter, ready-mixed concrete). That is, it is usually carried into the site by an agitator truck. Therefore, when adjusting the consistency,
At the site, cement, fly ash, stone powder, etc. are added to the fresh concrete that has been brought in for adjustment. In that case, of course, in advance,
At the test kneading stage, a slump test or the like is performed to set the amount of the additive material to be remixed.

[0006]

However, in the conventional method as described above, a large amount of the additive material to be remixed is required, and as a result, it is troublesome to manage the additive material and adjust the addition in the field such as installing a charging facility. There was a drawback that it took too much time. In addition, in the case of placing a large amount of concrete, there is a problem in maintaining the uniformity of quality due to the adjustment for each transport vehicle. It is an object of the present invention to provide a new concrete consistency adjusting method as an alternative to such a conventional adjusting method.

[0007]

As means for achieving the above object, the present invention has been attempted to be used as a sizing agent for fiber walls or plywood materials for building materials, or as a mud adjusting agent for drilling mud water. We focused on a water-soluble polymer material commonly known as CMC (carboxymethylcellulose).
As is well known, (1) this water-soluble carboxymethyl cellulose easily dissolves in both cold water and hot water to form a viscous solution. (2) There is no change in viscosity with time. (3) Emulsion dispersibility and solid dispersibility are excellent. (4) Has an adhesive action. (5) Insoluble in oil, grease and organic solvents. (6) Harmless to the touch of hands and body. (7) The quality is constant and uniform. (8) It is powdery or granular and easy to handle. It has the features of.

The present invention has succeeded in focusing on the characteristics of carboxymethyl cellulose and adding it as a thickener to green concrete to adjust the consistency. That is, carboxymethyl cellulose was added as a thickening agent to fresh concrete that did not set yet, and the consistency was adjusted on site. To be more specific, fresh concrete with a low consistency produced in a concrete plant is carried to the site by an agitator truck, and the fresh concrete is loaded into a screw feeder type re-kneader and during the transfer. In the above, the carboxymethyl cellulose consisting of the granular or powder is added as a thickener, and the consistency of the green concrete is adjusted while uniformly kneading.
That is, it is to adjust the consistency to be suitable for concrete construction such as slip form method.

[0009]

[Working] As described above, the present invention adjusts the consistency by adding carboxymethyl cellulose, which is extremely water-soluble and has the functions of viscosity and adhesiveness, to fresh concrete as a thickener. Since it does not require a large amount of additives such as cement and fly ash as in the past, it is possible to quickly obtain an appropriate consistency by adding an extremely small amount of a thickener made of carboxymethyl cellulose. You can

[0010]

EXAMPLES Next, the method of adjusting the consistency according to the present invention will be specifically described based on examples. First, ready-mixed concrete with a slump value of 8 cm manufactured in a concrete plant is manufactured. Table 1 shows the mixing ratio of the base concrete.

[0011]

[Table 1]

[0012] Next, this fresh concrete was carried into the site by an agitator truck and put into a re-kneader, and a thickener made of carboxymethyl cellulose, in the examples, (Sanyo Kasei product name Sandrock and Mitsui Siamit product Name P-502) was added and mixed with stirring. Then, the slump value and the air amount of the obtained fresh concrete were measured. Table 2 shows the measurement results of the amount of addition and the change in consistency with time.

[0013]

[Table 2]

As shown in this table, the slump value is
Adjusted by the minute order. It was confirmed that the strength development after curing was slightly improved as compared with that without addition. From this, if the slump is 3 cm or less, the slip-form method can be applied and the formwork can be omitted.

[0015]

As described above, the method for adjusting the consistency according to the present invention is extremely water-soluble,
Moreover, since the viscosity of the fresh concrete is increased and the so-called consistency is adjusted by using a thickener made of carboxymethyl cellulose having viscosity and adhesiveness, the following effects are exhibited. (1) The consistency can be adjusted on the order of minutes with an extremely small amount of addition. (2) Since the thickener to be added is in the form of powder or granules, it is easy to handle and the adjustment process is easy. Therefore, the management of the entire work is simplified. Since an agitator truck can be used, the existing ready-mixed concrete factory can be used. This does not require a special cement concrete plant to be installed. This allows the slip-form construction method to be applied, thus reducing the cost required for removing the formwork. (3) Further, by using the concrete whose consistency is adjusted according to the present invention, the work of assembling and disassembling the formwork, which was conventionally indispensable for concrete work, is eliminated, and the slip-form construction method can be quickly constructed. .. (4) It does not affect the quality of the concrete itself after curing and solidification.

Claims (1)

[Claims] 1. A method of adjusting the consistency of concrete, which comprises adding a thickener made of carboxymethyl cellulose to fresh concrete that has not yet solidified to adjust the consistency of the fresh concrete.