Interactions Between Comb-Type Superplasticizers and Slag Cement Pastes

This paper describes how comb-type superplasticizers are widely used for producing self-compacting or high-strength concrete. Recently, slag cement binders have been developed for their contribution to sustainable development and for their capacity to improve the durability of concrete. In order to enhance the use of slag cements in concrete formulation, it appears important to progress in the knowledge of their interaction with comb-type superplasticizers. The paper discusses about the polymer adsorption capacity on blast furnace slag and laboratory prepared mixes of slag and cement compared with portland cement. The authors observed that the substitution of cement with a very slow reactive binder like slag at early age, which induces then a different polymer adsorption capacity, allows to obtain a polymer adsorption less sensitive towards sulphate ions concentration. Besides, the authors observed that the dispersing effect of polycarboxylate polymer (PCP) was higher on slag cement paste than on portland cement paste. Therefore, slag cements seem to be interesting in concrete formulation because their interactions with superplasticizer seem to be less affected by the chemical composition of cement, and the superplasticizer effect is enhanced.