JPS63162562A - Admixing agent for cement - 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 (Field of Industrial Application) The present invention relates to an admixture for cement, and more particularly to an admixture for cement comprising a dispersant for cement contained in an organic hydrogel.

(Conventional technology) Generally, concrete, mortar, etc. using cement,
When manufacturing pastes and the like, cement dispersants called water reducers, high performance water reducers, or superplasticizers are used. Dispersion 4" is suitable for use in high-strength concrete because it significantly reduces the amount of water used, resulting in a cured product with high strength, and even with a reduced amount of water used, sufficient workability can be obtained. It has also been praised for use in fluidized concrete and other applications.

However, the cement composition mixed with this dispersant is
Immediately after kneading, it exhibits excellent fluidity, but it has the disadvantage that initial consistency is poorly maintained and the fluidity rapidly decreases over time. This decrease in fluidity is called slump loss, and for this reason, when producing fluidized concrete, a method is adopted in which a dispersant is added at the pouring site to raise the slump to a predetermined value, and then the concrete is poured immediately. For this purpose, equipment and quality control personnel are required.

Furthermore, after the dispersant is added to the truck agitator, the drum of the truck agitator must be stirred and mixed at medium or high speeds, which generates noise and exhaust gas, which poses health problems for nearby residents and field workers in urban areas. becomes.

Several methods have been proposed to address these problems. For example, (1) a method in which the dispersant is added in several portions (Japanese Patent Publication No. 19856/1985), (2) a method in which four spreading agents are used together, (3) a method in which the dispersant is added in the form of whole particles (
t# Publication No. 54-139929, Publication No. 221/1982
354 Publication), etc., but method (1) may complicate the process and is impractical, method (2) does not have a sufficient effect of preventing slump loss, and method (3) ) method requires a granulation operation, which is disadvantageous in terms of cost, and also has drawbacks such as the occurrence of localized pleating caused by undissolved dispersant.

(Problems to be Solved by the Invention) Therefore, as a result of intensive research in order to solve the above-mentioned drawbacks, the present inventors found that by incorporating a dispersant into the organic hydrogel, it is possible to prevent the decline in fluidity due to slump loss and maintain a constant flowability. It was discovered that the fluidity of the liquid can be maintained, and based on this knowledge, the present invention was completed.

(Means for Solving the Problems) According to the present invention, there is provided a cement admixture characterized by containing a cement dispersant in an organic hydrous gel.

The cement admixture of the present invention consists of an organic hydrogel containing a cement dispersant.

Specific examples of such water-containing gels include, for example, dengun-acryloni) IJ Ruglat copolymer system, carboxymethyl cellulose system, polyacrylonitrile system, polyethylene oxide system, vinyl acetate-acrylate copolymer system, vinyl alcohol-acrylic acid system. Hydrogels obtained by absorbing an aqueous dispersant solution into superabsorbent polymers such as salt copolymers, polyacrylates, and olefin-maleic anhydride copolymers; polyacrylates and olefin-maleic anhydride copolymers; Polymers such as polymer salts.

Examples include a hydrogel obtained by reacting a carboxylic acid salt with a crosslinking agent in the presence of an aqueous dispersant solution.

The above highly absorbent yl” IJ mama-polycarboxylic acid b
There are no particular restrictions on the type, and any commercially available products may be used.

The fU of the dispersant and water contained in the organic hydrogel is not particularly limited, but is usually 1 to 20 times the solid content of the superabsorbent polymer or polycarboxylic acid, and 1 to 4 times the amount of water.
00 times.

Further, the shape of the organic hydrous gel may be granular, plate-like, Zen-like, etc., and is not particularly limited depending on the method of use, but it is preferable to use it as a granular gel from the viewpoint of ease of dissolution.

The drainage used is not particularly limited, but usually tap water,
Groundwater etc. are used.

The cement dispersant used in the present invention may be any dispersant that is generally used as a cement dispersant, and specific examples include resinates, lignin sulfonates, oxycaldates, polyol complexes, and melamine. (AE) Water reducing agents, fluidizing agents, or polymers such as sulfonic acid formalin condensates or their salts, creosote oil sulfonic acid formalin condensates or their salts, naphthalene sulfonic acid formalin condensates or their salts, polycarboxylic acids or their salts, etc. A performance water reducing agent is exemplified.

Among these, when a fluidizing agent or a high performance water reducing agent is used, the effect of the present invention to prevent slump loss is remarkable.

Mighty FD (
(manufactured by Kako Co., Ltd.), NP-10, NP-20 (manufactured by Hiduru Master Builders Co., Ltd.), Work SOO (manufactured by Nippon Zeon Co., Ltd.), and Sunflow FBF (manufactured by Yamaba Kokusaku Pulp Co., Ltd.). In addition, a high performance water reducing agent has a high water reducing function and usually reduces the amount of kneading water by about 20 to 30%.A typical commercially available product is Mighty 150 (Kakosha M).
, Mailment F-10 (manufactured by Showa Denko) 1M-10 (
manufactured by Nippon Zeon Co., Ltd.).

In the present invention, the organic hydrogel is mixed in an amount sufficient to supply the required amount of the dispersant.

The amount of such a dispersant to be used is appropriately selected depending on the type of dispersant and the required performance of the target object, but it is usually 0.01 to 5 mm by weight, preferably 0.02 mm based on solid content, based on the cement.
It is used in a proportion of ~3% by weight.

There are no particular limitations on the type of cement to which the cement admixture of the present invention can be applied. For example, '
IIA Portland cement, early strength I Rutland cement, moderate heat? Rutland cement, alumina cement,
Examples include fly asche cement, blast furnace cement, silica cement, various mixed cements, and slag cement.

The timing of addition to the cement mixture can be selected as appropriate depending on the intended use. Examples include a method of adding it to cement in advance, and a method of adding it after kneading a mixture in advance. Although the cement admixture of the present invention may be used alone, it is generally used in combination with other dispersant* solutions.

Due to the calcium hydroxide in the cement, the dispersant contained in the cement is gradually released from the water-containing gel added in this manner, and a certain level of fluidity can be maintained.

The release rate can be controlled by changing the water absorption capacity of the dispersant solution contained in the hydrogel.

(Effect of the invention) Thus, according to the non-invention, the slan f is lower than that of the prior art.
A cement mixture with low loss and good fluidity can be obtained.

(Example) The present invention will be described in more detail with reference to Examples below. In addition, parts and units in Examples, Comparative Examples, and Reference Examples are based on weight unless otherwise specified.

Reference Example 1 Organic hydrogels (1) to (■) were obtained by making a super absorbent resin absorb water of various dispersant solutions shown in Table 1.

-1: Kakosha Mighty FD Umbrella 2: 8f Master Builders 1NP-10 Umbrella 3
:
NP-20 Umbrella 42 Made by Nippon Zeon Co., Ltd. Work 500 Umbrella 5 Made by Sanyo Kokusaku Pulp Co., Ltd. Sunflow FBF Medium 6 - Made by Seitetsu Kagaku Co., Ltd. Aqua Keep Umbrella 7: Sanyo Kasei Co., Ltd. Sun Wet Umbrella 8: Made by Kuraray Soderen Co., Ltd. KI gel implementation Example 1 The performance of the organic hydrous gels (1) to (Tsukasa) obtained in Reference Example 1 as admixtures for cement was evaluated according to the following concrete test conditions.

The following ingredients were weighed so that the amount of kneading was 401 kg, and the mixture was kneaded for 3 minutes using a variable mixer with a capacity of 501 kg. Thereafter, the rotation speed of the mixer was set to 2 rpm, and the slump value after a certain period of time was measured according to JIS A11ot.

The results are shown in Table 2.

Concrete composition component: Cement: Kotong? Fine aggregate mixed with 3 brands of Rutland cement: Oiyo Kagawa sand, Tohoku 2.61 Coarse aggregate: Seishin crushed stone, Tohoku 2.64 Admixture: Water-containing gel (I) ~ (■) Dispersion grinding secondary As shown in Table 3, the example of the present invention has a significant reduction in slump loss.
I understand that.

Claims (1)

[Claims] A cement admixture characterized by containing a cement dispersant in an organic hydrous gel.