Selection and Lab Research of Retarder for Phosphoaluminate Cement

For now, the compressive strength of Portland set-cements which have been eroded by formation fluids for many years would decline to some extent. Therefore, we have taken into account that phosphoaluminate cement with better performance has a possibility of applying to cementing engineering. The thickening time of phosphoaluminate cement paste is too short; hence, this article has studied on the influence of several commonly used retarders for Portland cement. The research shows that the same retarder has greatly different effects on Portland cement and phosphoaluminate cement. At 75°C and atmospheric pressure, the thickening times of phosphoaluminate cement slurry with different retarders and various added amounts have been tested. By comparison, we conclude that citric acid has the most efficient retarding effect. In the tested range, the thickening time and added amount of citric acid demonstrate a regular linear relationship. As a hydroxyl acid, citric acid can be used as a retarder for phosphoaluminate cement.