Interaction of Polycarboxylate-based Superplasticizers and Cements: Influence of Polymer Structure and C3A-content of Cement

摘要

Superplasticizers are commonly used in modern cementitious building ma- terials like self-compacting concrete. However, there are still many un- solved problems concerning cement/superplasticizer compatibility like poor flow behaviour, early slump loss or strong retardation. The objective of this study is to link the molecular structure of polycarboxy- late-ether type superplasticizers with their performance in cementitious systems in order to develop new enhanced products. Different experimental superplasticizers have been synthesized and ap- plied in cement pastes. The examined cements differed mainly in their C3A-content. Various methods have been used to characterize the ce- ment-superplasticizer interactions, like rheological measurements, con- duction calorimetry, and determination of the adsorption isotherm by TOC analysis, as well as XRD and TGA measurements. As result of this study, characteristic correlations between molecular struc- ture of the superplasticizer and C3A-content of the cement with respect to adsorption behaviour, rheology and retardation could be determined.