JPH10146823A - Cement for manufacturing ae concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a way to add a mixture as is under the state in its pulverulent body to a mixer at the kneading of an AE concrete by a method wherein the mixture is prepared by mixing powdered AE agent, water reducing agent, AE water reducing agent or high-efficiency water reducing agent as is under powdered state to cement powder at a desired mixing ratio in advance. SOLUTION: A cement for AE concrete consists of a mixed powder of a powdered chemical admixture selected from a group consisting of AE agent, water reducing agent, AE water reducing agent or high-efficiency water reducing agent, inorganic powder selected from a group consisting of stone dust, blast furnace slag powder and fly ash and cement powder. By mixing the mixed powder and the cement powder with a mixing machine such as a ribbon blender or the like after the mixed powder is prepared by mixing the powdered admisture and the inorganic powder in advance, the dispersion of the admixture becomes favorable. Further, when its mixing ratio is set to correspond to the ratio of admixture to cement to be mixed at the kneading of an AE concrete, no measurement of the adding ratio at a ready-mixed concrete factory becomes necessary, resulting in realizing a practical operational convenience.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement for producing AE concrete.

[0002]

2. Description of the Related Art Almost all concrete manufactured in ready-mixed concrete plants specified by JIS is AE concrete. In order to manufacture this AE concrete, an AE agent, a water reducing agent and AE are added to the basic materials of cement, water, fine aggregate and coarse aggregate.
Chemical admixture selected from water reducer or high performance water reducer (A
E concrete admixture) and kneaded in a batcher plant.

At this time, since the admixture is usually in a powder form, the powdery product is once dissolved in water to be in a liquid state, and then added. For this reason, the ready-mix plant has a dedicated measuring tank for the admixture, where the mixing amount of the admixture and the mixing water are measured and adjusted to achieve the target mixing amount and water amount. .

[0004]

As described above, the operation of dissolving the powdery admixture in water and adjusting the blending amount of the admixture and water is, to some extent, a routine work. Each time the type changes or the concrete mix changes, adjustments are required, which is a troublesome task.
However, if this is omitted and the admixture is added to the mixer in powder form, the admixture will not be uniformly mixed, and the effect of the admixture cannot be spread evenly throughout the concrete.
The present invention is intended to solve such a problem.

[0005]

According to the present invention, a powder of a chemical admixture selected from an AE agent, a water reducing agent, an AE water reducing agent or a high performance water reducing agent and a cement powder are provided to solve the above-mentioned problems. And a cement for producing AE concrete, comprising a mixed powder of:

Further, according to the present invention, a cement for AE concrete production comprising a powder mixture of the above-mentioned powder of the chemical admixture, an inorganic powder selected from stone powder, blast furnace slag fine powder or fly ash, and a cement powder is provided. provide.

Further, according to the present invention, there is provided a cement for producing AE concrete, comprising a powder mixture of the above-mentioned powder of the chemical admixture, the powder of the thickener, and the cement powder.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above-mentioned problems, the present inventors have attempted to premix and store an AE concrete admixture and cement powder. Then, it was examined how the powder mixture chemically changed. Initial predictions suggested that the powder of such admixture and the cement would react during storage and become unstable, degrading the original properties of the admixture, but the change was the most AEs containing lignin sulfonic acid compounds predicted to occur
Even when the water reducing agent is mixed for about half a year with the powder and cement powder mixed, the properties of the powder hardly change. It was found that the same quality as that of the concrete to which the admixture was added in a liquid state could be obtained.

Accordingly, the cement for producing AE concrete according to the present invention is a powdery AE agent, a water reducing agent, an AE water reducing agent or a high performance water reducing agent (including a high performance AE water reducing agent) used for the production of ordinary AE concrete. Is mixed powder in a desired ratio with a cement powder in a powdered state in advance, and this mixed powder can be added to a mixer as it is when the AE concrete is kneaded.

The admixture for AE concrete targeted in the present invention is, for example, a "chemical admixture for concrete" specified in JIS A6204. If the specified admixture satisfies the specified performance, a commercially available powdered AE admixture is used. , Water reducing agent, AE water reducing agent or high-performance water reducing agent.

The mixing ratio between the powdery admixture for AE concrete and the cement powder is not particularly limited, but it is assumed that it corresponds to the ratio of the admixture to the cement mixed in the AE concrete kneading. If the cement of the present invention is used as it is, the intended AE concrete can be manufactured, and it is not necessary to measure the ratio of the admixture to the cement added in the ready-mixed concrete plant, which is convenient in actual operation.

Conventionally, for example, AE containing an AE water reducing agent
In concrete, 0.2% by weight to cement
An AE water reducing agent of 5% to 0.375% (in terms of powder) is added (actually dissolved in water and added), but in the cement of the present invention, this powdery AE water reducing agent is added. May be added to and mixed with cement in an amount of 0.25% to 0.375%.

In order to mix and uniformly disperse the powdery admixture and the cement powder, a mixing machine such as a ribbon blender, a V-type mixer, and a double cone type mixer may be used.

Further, a powdery admixture and an inorganic powder such as stone powder,
If a mixed powder in which blast furnace slag fine powder or fly ash or the like is preliminarily mixed is mixed with the cement powder, the dispersion of the admixture is further improved. The mixing ratio (weight ratio) between the powdery admixture and the inorganic powder is 1: 5 to 1:
The range may be set to 20. Therefore, in this case, the cement for AE concrete according to the present invention is selected from AE agent, powder of chemical admixture selected from water reducing agent / AE water reducing agent or high performance water reducing agent, stone powder, blast furnace slag fine powder or fly ash. It consists of mixed powder with inorganic powder and cement powder.
What is necessary is just to correspond to the ratio with respect to cement mix | blended at the time of concrete manufacture.

The limestone powder as the inorganic powder is preferable because limestone powder can be used stably in terms of quality and supply. This limestone powder is standardized in JIS A 5008 and is widely used as a filler for asphalt pavement, but it is preferable to use this in the present invention. The cement of the present invention containing such stone powder, furthermore, fly ash or blast furnace slag fine powder can further improve the fluidity of AE concrete.

A high-performance water reducing agent (including a high-performance AE water reducing agent) is used in AE concrete with further improved water-reducing properties. According to the present invention, the powder of the high-performance water-reducing agent and the cement powder are used. May be mixed to obtain a desired ratio. High performance water reducing agent powders include aminosulfonic acid type, naphthalenesulfonic acid type, polycarboxylate, melaminesulfonic acid and its ether type, alkyl allylsulfonic acid type, ligninsulfonic acid type,
A maleic acid copolymer or a natural resin acid can be used.

Further, when a powder of a thickener such as methylcellulose (MC) or HEC (hydroxyethylcellulose) or a biopolymer of microbial fermentation such as welan gum is added to the cement of the present invention, the material separation resistance of AE concrete is improved. be able to. Welan gum has a cell number of Alcaligens ATCC
Microbial fermentation polysaccharide produced by 31555 species.

In general, when such a thickening agent (particularly welan gum) is added to concrete, the thickening agent may not mix well and may be in the form of a stick (lump). When the powder is mixed with the powder mixture of the powdery admixture and the cement, the thickener can be dispersed relatively well. Therefore, according to the present invention, as cement for producing AE concrete having material separation resistance, A
Provided are a powder of a chemical admixture, a powder of a thickener, and a powder mixed with a cement powder selected from E agents, water reducing agents, AE water reducing agents and high performance water reducing agents.

Hereinafter, as a typical example, a test example of the cement of the present invention obtained by mixing powder of a lignin sulfonate-based AE water reducing agent and cement powder will be described.

To ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) was added 0.25% by weight of a lignin sulfonate-based AE water reducing agent (trade name: Pozzolith No. 8) as powder, and the mixture was thoroughly mixed with a ribbon blender. Stirred. The resulting admixture-dispersed cement is packed in a normal cement bag,
Saved for 6 months.

Using the stored admixture-dispersed cement, tap water, fine aggregate (river sand) and coarse aggregate (crushed stone), slump: 8 ± 2.5 cm, water-cement ratio: 55
%, Fine aggregate ratio: 48%, and kneaded with a mixer.

The obtained concrete had a slump of 9.
0cm, air volume = 3.8%, concrete temperature = 20.3
° C.

For comparison, instead of adding the admixture-dispersed cement to a mixer, instead of mixing the same amount of cement and the same amount of the same AE water reducing agent (dissolved in water), separate Was added. The concrete mixing conditions are exactly the same as in the above case. The obtained concrete had a slump of 8.5 cm, an air amount of 4.2%, and a concrete temperature of 20.2 ° C.

From this test, it can be seen that even when the mixed powder of the AE water reducing agent and the cement is stored for 6 months, the performance on concrete is almost deteriorated as compared with the case where a fresh AE water reducing agent is added immediately before kneading. It can be seen that good AE concrete can be obtained without performing.

The same test was carried out for other admixtures for AE concrete, but almost no admixture whose performance was so deteriorated that it could not be used was found.

[0026]

As described above, the cement for producing AE concrete according to the present invention can be used in the production of AE concrete in a ready-mixed concrete plant without deteriorating the quality of AE concrete. The effect is that the troublesome operation of melting and measuring can be omitted. Further, according to the present invention, it is possible to supply a brand-specific AE concrete cement product according to the properties of the intended AE concrete to the market.

Continuation of front page (72) Inventor Masato Yoshizaki 1-29 Kitahama Higashi, Chuo-ku, Osaka-shi, Osaka

Claims (4)

[Claims] 1. A cement for producing AE concrete, comprising a powder mixture of cement powder and a powder of a chemical admixture selected from an AE agent, a water reducing agent, an AE water reducing agent or a high performance water reducing agent. 2. Powder of chemical admixture selected from AE agent, water reducing agent / AE water reducing agent or high performance water reducing agent, inorganic powder selected from stone powder, blast furnace slag fine powder or fly ash, and mixed powder with cement powder A cement for producing AE concrete comprising: 3. A cement for the production of AE concrete, comprising a powder of a chemical admixture selected from an AE agent, a water reducing agent, an AE water reducing agent or a high performance water reducing agent, a powder of a thickener, and a mixed powder with a cement powder. 4. The cement for producing AE concrete according to claim 3, wherein the thickener is welan gum.