Cement setting accelerator and method of manufacturing the same

Details Cement setting accelerator and method of manufacturing the same Cement setting accelerator and method of manufacturing the same

1990-10-15

1992-11-03

Dixon, Jr., William R.

Compositions: coating or plastic

Materials or ingredients

Additive materials for inorganic cements which contain a...

106692, 106695, 106792, 106796, 106799, C04B 732, C04B 736, C04B 4000, C04B 200

Patent

active

051603764

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a cement setting accelerator and a method of manufacturing the same, particularly, to a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, and also permits controlling the cement setting and hardening time as desired by increasing the addition amount of the accelerator.


PRIOR ART

Cement setting accelerators which permit accelerating the setting and hardening of a cement composition mixed with water are disclosed in Published Examined Japanese Patent Applications 56-27457 and 55-11635. The accelerator disclosed in Application 56-27457 noted above comprises calcium aluminate, sodium aluminate and sodium carbonate. The accelerator is certainly satisfactory in its capability of accelerating the setting of a cement composition. Specifically, a cement composition mixed with the cement setting accelerator disclosed in this prior art begins to set 30 seconds to 3 minutes after mixing of the composition with water, and the cement setting is substantially completed in about 10 minutes. However, it is difficult to retard as desired the initial setting time of the cement composition containing the cement setting accelerator disclosed in this prior art and mixed with water.
To be more specific, a cement paste having the setting accelerator added thereto begins to set promptly. Therefore, there is the defect that the cement paste begins to set before actual use when it is transported to a preferred position from the mixed position. It should also be noted that the cement setting accelerator disclosed in Application 56-2745 noted above certainly permits producing the particular effect in the case of a so-called "dry method", in which the accelerator is mixed previously with a cement composition and a cement paste is prepared by adding water to and mixing the composition. However, the setting acceleration effect is less than about half the level in the dry method in the case of a so-called "wet method", in which the cement setting accelerator is added to a cement paste prepared first without using the accelerator.
The technique disclosed in the other prior art, i.e., Application No. 55-11635, also gives rise to problems similar to those inherent in the Application No. 56-27457. In addition, the cement setting accelerator disclosed in Application No. 55-11635 is defective in that the initial setting time and the hardening performance are greatly changed depending on the kind of cement composition to which the accelerator is added.
Under the circumstances, it is very important in this technical field to develop a cement setting accelerator which permits promptly setting a cement composition mixed with water with a small amount of addition, which permits controlling the cement setting time as desired by increasing the addition amount of the accelerator, and which also permits sufficiently promoting the setting and hardening of a cement composition even in the case of the wet method.


DISCLOSURE OF THE INVENTION

According to the present invention, there is provided a cement setting accelerator consisting of a composition comprising 100 parts by weight of a sintered powdery material containing 4.25 to 85% of 3CaO.2Na.sub.2 O.5Al2O.sub.3, 0.75 to 15% by Weight of Na.sub.2 SO.sub.4, and at most 95% of Na.sub.2 O.Al.sub.2 O.sub.3 ; 5 to 70 parts by weight of an alkali metal carbonate powder; and at most 170 parts by weight of a lime powder (described embodiment 1).
The present invention also provides a method of manufacturing a cement setting accelerator defined in claim 1, characterized by comprising the steps of sintering at 1150.degree. C. or more a raw material containing 19.7 to 36.9% of Na.sub.2 O, 54.0 to 61.8% of Al.sub.2 O.sub.3, 0.9 to 17.8% of CaO, and 0.4 to 8.5% of SO.sub.3 so as to obtain a sintered body; pulverizing the sintered body; and adding 5 to 70 parts by weight of an alkali metal carbonate powder and at most 170 parts by weight of a lime powder to 100 parts by weight of the po

REFERENCES:
patent: 4650523 (1987-03-01), Kikuchi et al.
patent: 4798628 (1989-01-01), Mills et al.

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