Vibrorheology of fresh cement-based materials with different compaction energy

Abstract

Vibration is commonly applied to the placement of cement-based materials to improve their fluidity and compactness. Appropriate compaction could ensure the designed performance by preventing the formation of voids and cavities within a structure. In recent years, the application of vibration has been extended to the rheology control of 3D printable concrete as well. While previous studies have reported on the effective radius of compaction and rheological changes in cement-based materials induced by poker-type vibrators, there has been limited in-depth research on the rheological behavior beyond this effective radius, particularly in relation to the compaction energy. This study investigates the rheological behavior of a cement-based material under controlled vibration energy across a wide range of shear rates. A novel device is proposed for the precise control of compaction energy, in terms of the energy transfer rate per unit volume (power density) of vibration, and the vibrorheology under various power densities is measured. Experimental results reveal that viscosity at a low shear rate decreases proportionally to power density, while vibration has negligible effects on viscosity at a high shear rate. Furthermore, a correlation between power density and normalized yield stress is established, along with the effects of varying water-to-cement ratios. The study also discusses the influence of the vibration frequency on the effective radius of the poker-type vibrator.