Mischen von Hochleistungsbetonen

The Mixing Process of High Performance Concrete

Based on the current knowledge it is feasible to develop high performance concretes with special features such as self compacting ability, a compressive strength significantly above the average of standard concrete and a noticeable increased durability. The 4-materials system, a basic principle of the standard concrete production, is substituted by a 5- or 6-materials system that is characterized by a considerable reduced amount of water. Due to their complex mix composition high performance concretes show enhanced requirements concerning the mixing process. Conventional mixing systems are able to produce a high quality outcome for standard concretes within a short time. In contrast to that, a proper prediction of high performance concretes requires a more intensive input of mixing energy in order to deliver a concrete with the desired fresh concrete properties.
Current research activities at the Department of Building Materials, Building Physics and Building Chemistry at the TU Darmstadt prove considerable advantages of higher agitator velocity concerning the fresh concrete characteristics of HPC. An intensive and fast disintegration of cement particles significantly improves rheological attributes of the concrete and sustains them over a longer period of time. The usage of a suspension mixer enables a noticeable reduction of the mixing time and simultaneously decreased energy consumption.