Paste Rheological Thresholds of Self-Compacting Concrete: Influence of Cement and Tuff Powder from Xizang, China

The paste rheological threshold theory has been proven to effectively predict the workability of self-compacting concrete (SCC). The paste rheological thresholds of SCC are influenced by the properties of cement and other powders. The properties of the powders are represented by the powder fitting coefficient (n) and the intrinsic viscosity ([η]), which appear in the formula for determining the rheological thresholds of paste. However, the powder parameters are unknown for various brands of cement and tuff powder (TP). Therefore, a parameter model expressing the relationships between powder parameters and the powder’s properties was proposed in the research. The specific surface area (SSA) and zeta potential (ζ) were chosen as indicators of the powder’s characteristics. Three commonly used brands of cement and one type of TP in the Xizang region of China were employed to produce SCCs based on the paste rheological threshold theory. The iterative calculation method was employed to determine the powder parameters. Binary linear regression analyses were conducted on the n and [η] values of the eight powders concerning their SSA and ζ. As a result, the n and [η] values can be calculated with greater accuracy using the established relationships. Finally, the parameter model was validated using a different brand of cement. A mortar and three SCCs were tested to assess the accuracy of the parameter model. The validation experiments confirmed the robust reliability of the parameter model. This research significantly enhances the precision of the paste rheological threshold theory.