JPH0970812A - Mortar or concrete manufacturing method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To sufficiently and evenly disperse a fine powder which cannot be uniformly dispersed by kneading with a conventional mixer, to obtain a high-quality mortar having excellent properties such as strength development and fluidity. Produce concrete. SOLUTION: Ultrasonic vibration is applied at the time of kneading or after the kneading is completed and before the kneading is completed. [Effect] Since aggregates are loosened and uniformly dispersed, hydration proceeds smoothly, and the strength development of mortar or concrete is improved. In addition to increasing the filling rate of the constituent materials, the kneading water filling the gaps of the agglomerates becomes free water, which contributes to the improvement of fluidity. Since the amount of the water reducing agent and the kneading time by the mixer can be reduced, a high quality mortar or concrete can be efficiently provided at low cost.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing mortar or concrete, and more particularly to a method for producing high quality mortar or concrete by promoting the dispersion of powder in a kneaded product.

[0002]

2. Description of the Related Art Conventionally, mortar and concrete generally contain chemicals such as cement, aggregate, various admixtures and water reducing agents.
After kneading with water in a mixer, it is poured into a form using a concrete pump or the like.

There are three types of mixers used in the production of ready-mixed concrete: a tilting mixer, a pan-type forced kneading mixer, and a biaxial forced kneading mixer. Among them, the tilting type mixer is one in which a concrete material is put into a drum having a fixed blade therein, and the drum is rotated to scrape, drop and cut back to mix. In addition, the bread-type forced kneading mixer,
A concrete material is put into a mixing pan and kneaded with a rotating stirring blade. Further, the two-axis forced kneading mixer is a machine for horizontally and vertically moving and mixing the concrete material by rotating two horizontal shafts having stirring blades provided in the mixing pan. is there.

[0004]

Cement, admixture and fine aggregate in mortar and concrete are prone to agglomerate. However, in the above-mentioned kneading with a mixer, powder in mortar or concrete is sufficiently mixed. Cannot be evenly dispersed.

The powder referred to herein has a particle size of 100.
Although the particles have a size of μm or less, particularly the aggregation of particles having a size of 1 μm or less easily affects the quality of the mortar or concrete.

[0006] Since powders such as cement and admixtures are more hydrated as they are more uniformly dispersed without agglomerating, mortar and concrete having improved dispersibility of powders have good strength development. Further, when the powders of cement, admixture and aggregate aggregate, the gaps of the aggregates are filled with the kneading water, so that the amount of water necessary for maintaining the fluidity of the mortar or concrete is reduced and the fluidity is impaired. Therefore, the fluidity of mortar and concrete with improved dispersibility of powder becomes good.

Therefore, conventionally, in order to accelerate the dispersion of the powder, a method of lengthening the kneading time or a method of increasing the amount of the water-reducing agent is usually adopted, but the method of lengthening the kneading time is used. However, the method of lowering work efficiency and increasing the amount of use of the water reducing agent has a drawback that the manufacturing cost increases.

On the other hand, in recent years, in order to develop a high compressive strength of 60 N / mm ² or more and to secure good workability, silica fume or a brane value of 8000 cm ² / g or more is used as a mortar or concrete material. Increasingly, fine particles such as granulated blast furnace granulated slag are used as an admixture. These fine particles are particularly likely to aggregate,
It is difficult to loosen and disperse the agglomerates only by kneading with a mixer, but it is clear that if the agglomerates can be loosened and uniformly dispersed, the desired performance can be further improved.

The object of the present invention is to disperse even fine powder which cannot be uniformly dispersed by kneading with a conventional mixer, so that high-quality mortar or the like having excellent properties such as strength development and fluidity can be obtained. It is an object to provide a method for producing concrete.

[0010]

A method for producing mortar or concrete according to the invention of claim 1 is a method for producing mortar or concrete by kneading cement, aggregate and the like with water. Is added to promote the dispersion of the powder in the kneaded product.

A method for producing mortar or concrete according to a second aspect of the present invention is a method of putting mortar or concrete obtained by kneading cement, aggregate and the like with water into a mold, after kneading the materials. It is characterized in that vibration by ultrasonic waves is applied to accelerate the dispersion of the powder in the kneaded product before the completion of putting in the mold.

The method for producing mortar or concrete according to claim 3 is characterized in that the method according to claim 1 and the method according to claim 2 are combined.

When kneading cement and aggregate with water to produce mortar or concrete, at the time of kneading or between the end of kneading of materials and the end of placing in a mold,
By imparting vibration by ultrasonic waves, it is possible to effectively loosen the agglomerates of the powder and uniformly disperse them. Therefore, even with the same kneading time as in the conventional method, aggregates such as cement and admixture are loosened and uniformly dispersed, so that hydration proceeds smoothly and strength development of mortar or concrete is improved. Aggregates such as cement, admixtures and aggregates are loosened and uniformly dispersed, so that the filling rate of the constituent materials is increased. Further, the kneading water filling the gaps of the agglomerates becomes free water, which contributes to the improvement of the fluidity of the mortar and concrete, and thus the good fluidity can be obtained. That is, after the kneading is started, when the constituent material of the mortar or concrete is ultrasonically dispersed, a part of the initial hydrate of cement is peeled off from the cement particles, which become fine particles, which effectively acts to improve the filling rate of the constituent material. , Contributes to improvement of liquidity. Further, as a result, the amount of kneading water is reduced, the strength development is further improved, and the amount of water reducing agent used is reduced, so that the manufacturing cost of mortar and concrete can be reduced. Such effects are exhibited.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The method of the present invention is carried out in the same manner as in the prior art except that ultrasonic vibration is applied to the kneading material during the kneading of the material or between the completion of the kneading of the material and the completion of the kneading in the mold. can do.

In the present invention, in order to enhance the dispersion effect due to ultrasonic vibration, it is preferable to use an ultrasonic oscillator having a large output and a small frequency, specifically, an output of 0.3 to 1.2 kw. It is possible to preferably use the one having a frequency of 15 to 50 kHz.

From the viewpoints of dispersion efficiency and protection of the ultrasonic transmitter, ultrasonic vibration is preferably applied to the kneaded product after the addition of water.

Specifically, the method of the present invention comprises the following [i], [i]
i] can be implemented by one or both.

[I] An ultrasonic transmitter is attached to a conventional mixer, and ultrasonic vibration is applied during kneading. For example, after kneading with a mixer for about 0.5 to 3 minutes, ultrasonic vibration is applied while the mixer kneading is continued, and kneading is further performed for 0.5 to 2 minutes. [ii] After kneading for about 0.5 to 5 minutes with a mixer, the mixture is placed in a container equipped with an ultrasonic transmitter and ultrasonic vibration is applied for 0.5 minutes or more, preferably until the completion of casting. Although there is no particular limitation on the order of feeding the materials to the mixer, it is advantageous to feed the materials having a fine particle size first and to give ultrasonic vibrations to them, because it is easy to promote the dispersion of the powder.

[0020]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Examples 1 and 2 As the concrete material, ordinary portland cement manufactured by Mitsubishi Materials Co., Ltd., sand sand from Kisarazu, crushed stone from Hachioji (hard sandstone, 2005), and high performance water reducing agent Mighty 150 manufactured by Kao Corporation were used. Using the 50-liter pan-type forced kneading mixer having the material composition shown in Table 1, concrete was kneaded by the following method, and its fresh properties and compressive strength under standard water curing were measured, and the results are shown in Table 2. It was shown to.

[0022]

[Table 1]

Example 1: Output of 1.2 kW and frequency of 2
The concrete was kneaded using a mixer with a 6 kHz ultrasonic transmitter attached to the bottom of the pan. Kneading was carried out for 2 minutes after all materials were charged, and ultrasonic vibration was applied for 1 minute during the latter half of kneading.

Example 2: After all the materials were added and kneaded for 2 minutes, the kneaded material was placed in a container equipped with an ultrasonic transmitter having an output of 1.2 kW and a frequency of 26 kHz, and ultrasonic vibration was applied. It was given for 1 minute.

Comparative Example 1 A pan-type forced kneading mixer was used for 2
The same procedure as in Example 1 was carried out except that the kneading was carried out for 1 minute, and the results are shown in Table 2.

[0026]

[Table 2]

As is clear from Table 2, by applying ultrasonic vibration to the fresh concrete, the slump developability of the fresh concrete is improved and the slump loss is reduced, so that the workability of the concrete is improved and the hardening is achieved. The strength development of the body is improved.

Example 3 As materials for concrete, ordinary Portland cement manufactured by Mitsubishi Materials Corp., slag fine powder manufactured by Mitsubishi Materials Corp. (brain value 8100 cm ² / g), mountain sand from Kisarazu, crushed stone from Hachioji (hard sandstone, 2005), a high performance water reducing agent Mighty 150 manufactured by Kao Co., Ltd., and with the ingredients shown in Table 3, using a 50-liter pan-type forced kneading mixer, all the ingredients were added and kneaded for 2 minutes. Then, the kneaded material was put into a container in which an ultrasonic transmitter having an output of 1.2 kW and a frequency of 26 kHz was installed, and ultrasonic vibration was applied for 1 minute. The fresh properties of the obtained concrete and the compressive strength of standard curing at a specified age were measured, and the results are shown in Table 4.

[0029]

[Table 3]

Comparative Example 2 The same procedure as in Example 3 was carried out except that ultrasonic vibration was not applied after kneading for 2 minutes in a pan-type forced kneading mixer.
The results are shown in Table 4.

[0031]

[Table 4]

As is clear from Table 4, by applying ultrasonic vibration to the fresh concrete, the slump developing property and the slump loss property of the fresh concrete are improved and the strength developing property is improved.

[0033]

As described in detail above, according to the method for producing mortar or concrete of the present invention, kneading is performed at the time of kneading the constituent materials of the mortar or concrete, or after completion of kneading and before completion of placing in the mold. By applying ultrasonic vibration that promotes the dispersion of powder in the product, it is possible to improve the fluidity and strength development of mortar or concrete, and the amount of water reducing agent required to obtain the same fluidity and Since the kneading time by the mixer can be reduced, a high-quality mortar or concrete can be efficiently provided at low cost.

[Procedure amendment]

[Submission date] October 16, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

[0022]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Uemura 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Cement Research Center

Claims (3)

[Claims] 1. A method for producing mortar or concrete by kneading cement, aggregate and the like with water, wherein vibration at the time of kneading is applied by ultrasonic waves to promote dispersion of powder in the kneaded product. Method for producing mortar or concrete. 2. A method of putting mortar or concrete obtained by kneading cement, aggregate and the like with water into a mold, wherein ultrasonic waves are applied between the time when the mixing of the materials is completed and the time when the material is put into the mold. A method for producing mortar or concrete, characterized in that the dispersion of powder in a kneaded product is promoted by applying vibrations according to the above. 3. A method for producing mortar or concrete, characterized in that the method according to claim 1 and the method according to claim 2 are performed together.