Interfacial Interaction Between Polycarboxylate-based Superplasticizer and Cement Component Minerals

This paper is presented for abetter understanding of the interaction between polycarboxylate-based superplasticizer (PCA) and cement component minerals. The impact of PCA on the particle interaction among tricalcium silicate (C3S), dicalcium silicate (C2S) and the initial Portland cement hydrates ettringite (AFt) has been systematically examined. The zeta potential was highly dependent on the chemical composition of the solvent. Furthermore, it was demonstrated that adsorption always occurred between the minerals and anionic PCA in spite of their equal charge sign. For silicates (including C3S and C2S), the adsorption of high load Ca2+ formed a positive layer and subsequently adsorbed anionic PCA. For AFt, the direct adsorption onto AFt results from its strong electrostatic interaction. The high affinity of PCA to aluminate phase surface can be attributed to the high reactivity of tricalcium aluminate and its large specific surface.