STUDY ON WEIGHT LOSS OF CEMENT SLURRY DUE TO PRECIPITATION

The simulation experiment results of a number of typical weight loss under conditions of non-existence of filtration were presented. The time before the first increase of weight loss rate on the weight loss curve was defined as the precipitation period. The data analysis shown that the weight loss in the precipitation period can not be explained by the points of view of gelation alone or of the complex action of gelation and contraction of hydration volume. Therefore a concept of derivation of weight loss due to instability of cement slurry was figured out. The mechanism, the characteristics and the law of weight loss were described and the experimental data in the precipitation period were explained. The correlation between stability of cement slurry and its weight loss was revealed and the enhancing cement slurry stability was taken as a principle measure for control of the preliminary weight loss and prevention of gas channeling.