Effect of Alternating Current Field on Rheology of Fresh Cement-Based-Pastes (2021-12)¶

In order to further control the rheological properties of fresh cement-based pastes on demand, this paper investigated the influences of alternating current (AC) field on yield stress, plastic viscosity and thixotropic properties of fresh cement-based paste without or with mineral admixtures (including fly ash, granulated ground blast furnace slag and silica fume) by serials experiments and theoretical analysis. The results show that the yield stress greatly increased after 20min, the plastic viscosity and thixotropic area of fresh paste greatly increased after 10min with the action of applied AC field, and the rheological parameters changed more significantly with the AC voltage enlarged from 30V to 40V. Especially, the yield stress of paste increased exponentially with time under the action of AC field. The changes of the temperature of pastes were raised by the Joule heating generated by the AC field, which is the main reason for the rheology change of paste. This achievement will provide a new technical support to prevent the segregation and improve the stability of fresh concrete after casting by application of AC field.