Kurzfassung

The general purpose of this project is to attain a deeper understanding of the interaction properties of cement lime (CAC) with other aggregates in the formulation. This knowledge is indispensable to understand or predict the performance of refractory castables. This topic is already a priority field of investigation as long as hydraulic bond systems are in use. However most research work published in literature put focus on details (e.g. solely the temperature dependence of the setting...The general purpose of this project is to attain a deeper understanding of the interaction properties of cement lime (CAC) with other aggregates in the formulation. This knowledge is indispensable to understand or predict the performance of refractory castables. This topic is already a priority field of investigation as long as hydraulic bond systems are in use. However most research work published in literature put focus on details (e.g. solely the temperature dependence of the setting velocity, the setting velocity strength evolution as a function of time etc.). Very often the basic conditions how the tests were performed are not commented. Therefore the objective of this project is to control all known influences that affect the setting behaviour, the strength evolution, the drying behaviour and the high temperature performance. Beside the typical parameters temperature, relative humidity, workability (viscosity, compactibility), and CAC- microfines-additive combinations a key issue of this project is how the water-to-cement ratio (wcr) affects the strength evolution and in consequence the material performance at service conditions. To date the influence of wcr for CAC containing refractory castables was only evaluated as an issue for the adjustment of consistency of castables but not systematically in connections with their high temperature properties. Therefore wcr is a key value for calcium silicate products from the civil engineering industry but the influence was neglected for CAC containing refractory castables. This is because the CAC in refractory castables loses its functionality after the first heat-up and therefore is always seen as a temporary binder. The importance for the high temperature performance was always neglected or even worse in that case that it is often accused to reduce the refractoriness of the product.
It is expected that the proper adjustment of the wcr will significantly enhance the performance of refractory castable. It will be possible to determine the precise cement concentration for any ambient condition. During the project it will be carefully evaluated how the adjusted cement concentration affects the setting, hardening, drying and high temperature properties. For a proper material development it is indispensable to investigate every step of the whole lifecycle.» weiterlesen» einklappen