Title: Assessing Rheology of Self-Consolidating Paste Systems— A New Approach
Author(s): Usman Mahmood Raja, Thomas A. Bier, and Syed Ali Rizwan
Publication: Materials Journal
Appears on pages(s): 79-90
Keywords: Bingham and Herschel–Bulkley equations; repeatability; rheology; viscosity; yield stress
The rheology of a self-consolidating cementitious system (SCCS) is often characterized by its yield stress and viscosity. These parameters are traditionally determined through a rheometer. However, there is some variability in results obtained, which raises the question of reproducibility. The current paper proposes a simpler mechanistic approach for their determination. An optical setup, attached with a flow apparatus, is designed to map the behavior of a flowing cement paste in real time using digital image processing (DIP) techniques. To evaluate rheological parameters, a superposition principle was used with two possible cases based on whether or not the paste’s shear stresses exceed its yield strength. With the parameters obtained, Bingham’s linear and Herschel–Bulkley’s equations were modeled. The computed results showed a plausible agreement with rheometric measurements and provided a quantitative tool for assessing the rheology and stability of cementitious systems. The repeatability of results is also significantly improved.