JPH089498B2 - A method for retarding the hardening of cement containing lime aluminate. - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for delaying the hardening of a hydraulic cement-based material containing a lime aluminate salt having a high hydration rate by ozone-containing water. According to the present invention, the curing rate can be reduced without degrading other properties of the cementitious material.

[Conventional Technology and Problems Thereof] Aluminate lime salt contained in hydraulic cement (eg, alumina cement) has high adhesive strength, base / acid resistance,
It is known that it has excellent properties such as high heat resistance and low temperature curing property, and has a high hydration rate and high fastness. This early strength is a desirable property depending on the application, but for example (a) sufficient adhesion or use as a grout material,
(B) About the setting speed, with respect to the precision driving-in construction, (c) the adjustment of foam hardening time in the production of heat-insulating foam cement material, and (d) the approximation or adjustment of the hardening time with other hardening components in cement. It is desired to be easily adjusted and delayed.

Typical setting retarder for lime aluminate salt is gypsum, and many other retarders have been proposed.
However, since their actions are complicated and have side effects, there is a problem that an accurate delaying effect cannot be expected for a cement paste mixture. Furthermore, the conventional retarder tends to deteriorate the quality and strength of the cement-based cured product, because the components remain after the action.

The main object of the present invention is to overcome the above-mentioned problems and to propose a curing retardation method which is easy to work and control.

[Means for Solving Problems] According to the present invention, in a cementitious admixture containing hydraulic cement containing lime aluminate salt and water, ozone is allowed to be present together with the water. A method of retarding the cure of a base material is provided. In this case, the action of ozone can be adjusted by allowing the reducing substance to be present in the admixture in an amount smaller than that of ozone.

[Detailed Description of the Invention] (1) Example of cement containing lime aluminate The lime aluminate is CaO (hereinafter represented by C) and A.
It means a binary compound with l ₂ O ₃ (hereinafter represented by A). _{Typically, CA, C 3 A, C} 12 A 7, C 11 A 7 · CaX 2, CA 2, CA 6 and the like are known. As the hydraulic cement to which the present invention is normally applied, alumina cement having CA as a main component,
Portland cement containing about 7% or more (preferably 10% or more) of C ₃ A, modified Portland cement prepared by blending ordinary Portland cement with lime aluminate salt (for example, jet cement containing C ₁₁ A ₇ · CaX ₂ ), synthetic Examples include lime aluminate-based cement, and mixtures thereof. It should be noted that the present invention is considered to be particularly effective for alumina cement and / or jet cement, or a mixture of this and other hydraulic cement.

(2) Ozone As ozone used in the present invention, ozone obtained from an ozone generator utilizing silent discharge or electrolysis can be advantageously used. For example, ozone is inexpensively obtained by silently discharging oxygen or dry air with an AC voltage. O ₃ water used (may be an aqueous or supersaturated aqueous solution of ozone or ozone containing water such as ozone containing steam)
The concentration (% by weight) is about 0.01% or more, and generally about 0.
It is in the range of about 02 to 3%, usually about 0.05 to 2%, and even higher concentration is possible in the case of ozone-containing water vapor. The ozone supersaturated aqueous solution is obtained by introducing ozone or an ozone-containing gas into water under pressure. The ozone-containing water vapor is obtained by mixing ozone or an ozone-containing gas with, for example, saturated water vapor.
When ozone water containing about 0.3% by weight or more of ozone is used, it is generally preferable to knead by substantially sealing the mixer container for cement mixing.

In one embodiment, it is also desirable to use a small amount (for example, 2/3 or less equivalent to ozone equivalent of ozone of O ₃ water) of a reducing compound (for example, sulfite or nitrite) in order to reduce the action of O _3. is there. Further, the effect of ozone can be temporarily interrupted by adding the reducing substance to the cementitious mixture, and the effect of ozone after the consumption of the reducing agent can be achieved.
When the base-reactive aggregate is used as the aggregate in the cementitious mixture according to the present invention, the presence of ozone water also achieves a side effect of suppressing the alkali-silica reaction of the aggregate. .

(3) Specific Examples 1 to 3 of alumina cement and ordinary Portland cement
2 parts by weight of river sand was added and mixed with 1 part by weight of the mixture having a ratio of 1: 1. 3 parts by weight of the cement composition was placed in a mortar, 0.6 part by weight of water or the following O ₃ water was added, and the mixture was kneaded in a mortar to give a viscous duration (time until kneading becomes substantially impossible). ) Was measured. The results are shown in the table below. No cement additives were used for the purpose of detecting the effect of ozone.

As mentioned above, it was demonstrated that the presence of ozone in the miscible water effectively retarded the hardening of the cementitious material. That is, it was demonstrated that the hydration hardening property of the lime aluminate salt in the cement was reduced or substantially lost (stopped) by the action of ozone.

[Action and Effect] According to the present invention, setting delay of a hydraulic cement-based material containing a lime aluminate salt having a high hydration rate by ozone-containing water is achieved. The effect of ozone has not been sufficiently clarified, but ozone in the water mixed with the cement-based composition acts on the aluminate lime salt fine particles to modify the gel structure involved in the hydration reaction to improve the water content. It is thought to delay or stop the Japanese speed.

The lime aluminate salt contained in hydraulic cement (eg, alumina cement) has excellent properties such as high adhesive strength, base / acid resistance, high heat resistance, and low temperature curing property, and its hydration rate is large and fast. It is strong. In the present invention, only the hydration hardening rate of the aluminate lime salt is delayed or stopped, while other properties are retained. As a result, for example, (a) sufficient adhesion or use as a grout material, (b) precision driving construction, (c) adjustment of foam curing time in the production of heat-insulating foam material, (d) other delay in cement. With respect to the approximation or adjustment of the curing time with the hard curing component, an excellent effect can be achieved by easily adjusting and delaying the curing rate. Further, the conventional setting retarder tends to remain in the cement hardened product after its action to deteriorate the quality and strength, but in the present invention using ozone, such adverse effect does not exist.

 ─────────────────────────────────────────────────── --Continued from the front page Examiner Hideo Tokunaga (56) Reference JP-A-4-74740 (JP, A)

Claims (3)

[Claims] 1. A method for retarding the hardening of a cementitious material, characterized in that ozone is present together with water in a cementitious admixture containing hydraulic cement containing lime aluminate salt and water. 2. The method according to claim 1, wherein the action of ozone is regulated by the presence of a reducing substance in an amount smaller than that of ozone in the cementitious mixture. 3. The method of claim 1 or 2 wherein the cementitious admixture comprises alumina cement and / or jet cement.