Some aspects of cement chemistry regarding self-compacting concrete

The rheological behaviour of SCC during the very first hours of hydration is influenced by the formation of syngenite and ettringite and consequently depends on the alkali- and sulfate content of the liquid phase. The probability of phase formations was determined by thermodynamic calculations.
Powdered limestone and fly ash as well acting as nucleation sites for C-S-H. Hence, the early stage of hydration is accelerated and the retarding effect of several superplasticisers is partially compensated.
Due to the slow hydration of fly ash of merely 10 % after 3 month, for sec with high fly ash content durability testing procedures should be carried out at later ages than intended for normal concretes.

Author: J. Stark, M. Friebert

Section: Application of cement

Keywords: test