The suitability of a calcined kaolinitic filter cake arising from the pro-duction of high quality silica sand as SCM was tested as a promising field of application. The investigation comprises two different grades of materials. The first one represents a cross-section from one week of production. The other sam-ple has been subsequently prepared by sedimentation on a laboratory scale in order to investigate the impact of a lower sand content. The chemical and miner-alogical composition of both samples was determined by means of ICP-OES, XRD and FTIR. The laboratory sample yielded a higher kaolinite and a lower quartz content in comparison to the industrial product. The dehydration behavior was determined using TG/DTG. After thermal activation, the reactivity was in-vestigated by measuring the solubility of Al- und Si-Ions in alkaline solution. It turned out that a calcination temperature of at least 650 °C is required for a com-plete dehydroxilation. Heat of hydration was studied by isothermal calorimetry using a substitution rate of 20 wt%. The same substitution rate was chosen for the determination of strength activity index on mortar bars. Both materials provide a significant acceleration of the early hydration by pro-moting the aluminate reaction. After 28 days the higher kaolinite content of the laboratory sample leads to a higher activity index of 121 % in comparison to 102 % of the industrial product.    «

The suitability of a calcined kaolinitic filter cake arising from the pro-duction of high quality silica sand as SCM was tested as a promising field of application. The investigation comprises two different grades of materials. The first one represents a cross-section from one week of production. The other sam-ple has been subsequently prepared by sedimentation on a laboratory scale in order to investigate the impact of a lower sand content. The chemical and miner-alogical composition of both sa...    »