Determination of the energy consumption during the production of various concrete recipes

This article presents a report of the mixing of concrete on the laboratory scale in a single-shaft and twin-shaft mixer. For both mixers we selected five concrete recipes that cover a broad spectrum of concrete mixing techniques. The concrete recipes differ from each other amongst other things by virtue of the aggregate-sized distribution curves, water-cement ratio, flow properties, compressive strength and mixing times. The specifically volume-related application of energy - which is necessary for the homogenization of the particular recipe in the mixer - is an essential influencing variable. The comparison of the specifically volume-related application of energy is possible only if the concrete recipes possess the same homogeneity The time curve of the homogeneity plotted against the necessary mixing time indicates the mixing efficiency, which in turn is determined by an imaging measurement process. Comprehensive mixing experiments show that the resulting application of energy, measured via the current composition, does not provide sufficient information in order to define the actual homogeneity in the mixture. A method was developed for the purpose of comparing concrete mixtures based on various recipes with the same homogeneity in relation to the specifically volume-related application of energy. The particular application of energy can be determined via the required mixing time and the power output process in terms of time. (C) 2009 Elsevier Ltd. All rights reserved.