Investigating the Effects of Mixing Time and Mixing Speed on Rheological Properties, Workability, and Mechanical Propert
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RESEARCH PAPER
Investigating the Effects of Mixing Time and Mixing Speed on Rheological Properties, Workability, and Mechanical Properties of Self-Consolidating Concretes Ali Akbar Shirzadi Javid1
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Parviz Ghoddousi1 • Sadaf Aghajani1 • Hamed Naseri1 • Sahar Hossein Pour1
Received: 14 May 2020 / Revised: 7 August 2020 / Accepted: 17 August 2020 Iran University of Science and Technology 2020
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. Keywords Mixing energy Mixing time Mixing speed Workability Rheological properties Mechanical properties
1 Introduction
& Ali Akbar Shirzadi Javid [email protected] Parviz Ghoddousi [email protected] Sadaf Aghajani [email protected] Hamed Naseri [email protected] Sahar Hossein Pour [email protected] 1
School of Civil Engineering, Iran University of Science and Technology, Narmak, P.O. Box 16765-163, Tehran, Iran
The mixing procedure can significantly impact workability, one of the critical criteria for self-consolidating concretes (SCC). The self-consolidating concretes performance is usually determined by their homogeneity. SCC mixtures require more mixing energy so as to change into a homogeneous mixture because their ingredients are different from conventional concretes [1]. Some researchers have investigated the importance of mixing time [2–5]. De Franc¸a et al. [5] theorized that inappropriate mixing conditions could be caused by inadequate short mixing times. On
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