PURPOSE: To provide a cement admixture, cement compositions for quick-setting the concrete used in the fields of general civil engineering and construction, and a quick-setting process therefor.

CONSTITUTION: This cement admixture is characterized by containing a cement quick-setting agent, a setting retarder and an alkali aluminate in which the amount of the retarder is 3 to 30 pts.wt. per 100 pts.wt. of the cement quick- setting agent. The composition consists of cement and this cement admixture. The quick-setting process is characterized by separately force-feeding (A) the concrete which is composed of cement, the cement quick-setting agent, the setting retarder, when needed, the aggregates, and (B) a liquid containing an alkali metal aluminate, then mixing them and casting the mixture to the site. The use of the cement admixture shortens the gelation time and concrete setting time and improved the operation environments and workability.