Relative Behavior of Carboxylic and Phosphorous-Based Dispersants

摘要

The development of carboxylie-based PCE superplasticizers in the last 10 to 15 years has prompted the development of concrete applications which would have been of difficult accomplishment without such materials. The main difference between PCE superplasticizers and the products which were used before lie in the long slump retention which can be obtained with such products. Another important characteristic of PCE superplasticizers is that their efficiency is obtained at low dosage, and consequently they alter in a minimal way the chemistry of cement hydration. However PCE superplasticizers show a high sensitivity to small changes of the chemistry of the hydrating cement paste. A range of phosphorous-based superplasticizers have been developed that show greater robustness of performance, still having the characteristics of long slump retention, low hydration and hardening retardation and low dosage efficiency. In the present paper we investigate the particle-particle interactions in the presence of PCE and phosphorous-based superplasticizers.