Investigating the Effects of Mixing Time and Mixing Speed on Rheological Properties, Workability, and Mechanical Properties of Self-Consolidating Concretes

Abstract

The mixing process performs a critical role in the concrete microstructure, which defines the final product’s quality. Optimizing mixing time and mixing speed during the mixing process can reduce the unit price and energy consumption without impacting product quality. Furthermore, the energy consumption to manufacture self-consolidating concretes (SCC) is more than that of conventional concretes due to their compositions and structures. Due to the fact that rheological and mechanical properties assess the performance of concrete, the effects of mixing energy on the mentioned properties of self-consolidating concretes are taken into consideration simultaneously in the current investigation. Accordingly, different mixtures contained polysaccharide-based viscosity modifying agent and limestone powder are made under different mixing speeds and mixing times. Drawing on the results of mixing time, the optimum time for mixing is 8 min in this study in order to improve the workability and to provide ideal levels of rheological features such as minimum yield stresses (static and dynamic). In the aspect of mixing speed, double increasing from 20 to 40 rpm rises the slump flow by 5%. Besides, accelerating mixing speed increases dynamic yield stress by 37% for 11 min mixed mixtures, which is more than that of other mixing times mixtures’ dynamic yield stress increment. In the aspect of mechanical properties, mixing time increment increases the concrete’s compressive strength. Nevertheless, other mechanical characteristic criteria do not significantly depend on mixing energy.