JPH01119551A - Cement admixture - Google Patents

Abstract

PURPOSE:To prevent cracking and swelling as well as to allow cement to exhibit satisfactory strength by high-temp. short-time curing by properly blending aluminum sulfate with an alkali metal sulfate and a defoaming agent. CONSTITUTION:A cement admixture is composed of aluminum sulfate, an alkali metal sulfate such as sodium sulfate or potassium sulfate and a defoaming agent such as a silicone or nonionic defoaming agent. The amt. of the alkali metal sulfate used is about 50-300pts.wt. per 100pts.wt. aluminum sulfate and that of the defoaming agent is about 0.1-3pts.wt. per 100pts.wt. aluminum sulfate-alkali metal sulfate mixture. The admixture is used by about 2-10pts.wt. per 100pts.wt. cement. When the admixture is used, thermal cracking and swelling are not caused to mortar even by rapid curing with steam before setting, and strength is satisfactorily exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cement admixture, and particularly to a cement admixture that exhibits high early strength and is composed of aluminum sulfate, an alkali metal sulfate, and an antifoaming agent.

Conventional techniques and their problems> Conventionally, as a method for producing hardened cement with high early strength, cement is mixed with an admixture consisting of aluminum sulfate and silica thread compound particles, etc., without the need for spinning and curing.
A method was proposed in which the temperature was raised immediately and the material was cured at a high temperature (Patent Publication No. 52158/1983).

However, this method has many practical problems such as rapid setting of concrete and poor workability.Also, the strength of demolding after curing is not sufficient, and sagging and blistering may occur due to heat. It wasn't visually appealing.

As a result of various studies to solve the above problems, the present inventors have found that a certain level of workability can be achieved by using a cement admixture whose main components are aluminum sulfate, alkali metal sulfate, and an antifoaming agent. The present invention was developed based on the knowledge that a hardened cement product with excellent appearance without cracks or cracks, etc. can be obtained by developing the strength necessary for dewarming the formwork in a few hours by short-term high-temperature curing. It has been completed.

Means for Solving the Problems> That is, the present invention is a cement admixture comprising aluminum sulfate, an alkali metal sulfate, and an antifoaming agent.

The present invention will be explained in detail below.

As the cement according to the present invention, any cement can be used, such as various types of Portland cement such as normal, early strength, and super early strength, and various mixed cements mixed with island furnace slag, fly ash, etc.

The aluminum sulfate (hereinafter referred to as sulfuric acid) can be either anhydrous or hydrated, such as Al2(SO4)3.12-18H20, and can be used as a powder or an aqueous solution.

When it is in powder form, it is particularly preferable to use fine powder, for example, 100 mesh or less.

As the alkali metal sulfate (hereinafter referred to as alkali sulfate), ordinary sodium sulfate (hereinafter referred to as Na sulfate) and/or potassium sulfate (hereinafter referred to as sulfuric acid) can be used, but from the viewpoint of workability and strength development, sulfur rRNa is preferable. preferable.

The amount of alkali sulfate used is 50 to 300Xji parts, preferably 7 parts per part of sulfuric acid AJ1001.
0-200! Parts by weight, particularly preferably 80 to 150 parts by weight. If it is less than 501 parts, the solidification rate of the cement mixture will be fast, the workability will be poor, and the strength-enhancing effect will be small. When exceeding 300!31 parts, short-term strength development becomes rapid.

Examples of antifoaming agents include silicone type, nonionic type, alcohol, fatty acid, ether, fatty acid ester, phosphoric acid ester, polyether type, and fluorine type.

Specifically, silicone-based products include an oil type, a solution type in which the oil type is dissolved in a solvent such as toluene, and a silicone type in which fine inorganic powder is added to silicone oil.

Examples include emulsion dogin made from a compound made with a sulfuric acid compound, and emulsion dogin made using various emulsifiers. As the antifoaming agent, from the viewpoint of antifoaming effect and surface properties of the cured mortar, silicone-based and nonionic anti-foaming agents are preferable.

Antifoaming agents enable high-temperature curing of cement mixtures before setting, and prevent cracks on the concrete surface after high-temperature curing.
Furthermore, it is necessary for increasing the strength and improving the surface quality of the hardened cement body.

The amount of antifoaming agent used is @acid AJ1! : 0.1 to 6" x parts is preferable, more preferably 0.3 to 2 parts by weight, per 1001 parts by weight of the m-acid alkali mixture. 0.1] Li
If the amount is less than i part, the above effects will be lost, and if it exceeds 3 parts by weight, the effect will not change and it is not economical.

The amount of admixture used is 2 to 103 parts (preferably 6 to 71 parts by weight, more preferably 6 to 71 parts by weight) per 100 parts of cement. If it is less than 2 parts by weight, cracks may occur on the concrete surface after high temperature curing. There is a risk that this will occur, and the strength will develop quickly.Even if the number of parts exceeds 10, the effect of increasing strength will be small and it will not be economical.

The method of mixing the admixture is as follows: 1) Mix it with cement in advance. 2) Mix mortar and concrete cD at 11 o'clock. 3) Add at any time after (mixing mortar or concrete), for example, within 1 hour.

4) Any method can be used, such as mixing in a water bath solution. In addition, each material may be mixed simultaneously or separately as an admixture.

Furthermore, if necessary, commercially available cement water reducers, such as Eva,
The use of β-naphthalene sulfone [J[formalin condensate, melamine sulfonate, etc.] has corresponding effects.

When using the admixture of the present invention, inorganic compounds such as phosic acid, phosphoric acid, and silicofluorides or salts thereof, or oxycarboxylic acids or salts thereof such as citric acid, tartaric acid, and gluconic acid may be used as setting regulators. Can be done.

Furthermore, the appearance of the hardened cement can be improved by using silica flour, fly ash, pulverized blast furnace slag, etc.

Cement paste, mortar, and concrete (hereinafter referred to as concrete) may be formed by either casting in a formwork or centrifugal forming.

The concrete formed in this way is immediately heated at room temperature.
Preferably, after pre-curing for 20 minutes or more, the temperature is increased. The temperature increase rate should be 20 to 60°C/hour, taking into account the number of times the formwork will be used. If the temperature increase rate is faster than this range, thermal stress cracks are likely to occur on the concrete surface.

The holding temperature for curing is (peak temperature) 50°C or higher, preferably 60-90°C, and the curing time at peak temperature is 30-90°C.
It is sufficient to hold it for 90 minutes.

As a heating means, any of electricity, hot air, infrared rays, steam, etc. can be used, but steam curing is preferable from the viewpoint of developing strength.

After the hardened cement body is cured at the above-mentioned high temperature, it is immediately removed from the mold.
All 1 process is completed.

A hardened cement body obtained in a short time by such K treatment has a superior appearance and no change in durability compared to a hardened cement body using only ordinary Portland cement.

<Example> Next, the present invention will be further explained with reference to Examples.

Example 1 100 parts by weight of ordinary Portland cement (manufactured by Denki Kagaku Co., Ltd.), 200 parts by weight of fine aggregate (sand for Hime, FM=2.7),
Cement water reducer (product name: “Mighty 100” manufactured by Kao Corporation)
) A mortar consisting of a 0.51 lid part, a part placed in water 433, and 5 double wave parts of the admixture shown in Table 1 was kneaded according to JIS R5201, a mortar specimen (4 x 4 x 16 cm) was prepared, and it was aged for 20 minutes. I started taking care of myself. The temperature was raised at a rate of 40° C./hour, and when the temperature reached 80° C., it was held for 30 minutes, and the mold was demolded immediately thereafter. Observing the external appearance of concrete for 3 hours,
The compressive strength was measured on the 1st and 28th day. Experiments in history 6 and 8
A similar test was also conducted on mortar cured in a 20°C-80RH room. The results are shown in t-1-2.

Shishi-2 Experiments-16 and 17 use mortar in Experiments-6 and 8, respectively.Experiment-18 uses no admixture H, T: Handling time Example 2 Except for changing the admixture tt in the mixture of Experiment-7. was carried out in the same manner as in Example 1. The results are shown in Cloth-3.

From the results, the product of the present invention does not develop cracks such as cellulite even if it is steam-cured before condensation, and exhibits good short- and long-term strength.

<Effects of the invention> Even if rapid steam curing is performed before mortar condensation, no cracks or blisters occur due to heat, and not only does short-term and long-term strength develop well, but the surface of the cured mortar has gloss and is excellent in appearance. ing.

Patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] Cement admixture consisting of aluminum sulfate, alkali metal sulfate and antifoaming agent.