Abstract:

An experiment was carried out by using phosphorus gypsum rather than natural gypsum as cement retarder in portland cement to test its physical properties such as the setting time and decide its feasibility in cement production. The result shows that phosphorus gypsum works effectively in setting time and retarding the setting process. Besides，its indexes of physical property meet the requirments of the national standard.

Key words: phosphorus gypsum, retarder, the physical property of cement