Title: Acceleration Of Cement Blended with Calcined Clays with CaCl2, Microlimestone and CSH Seeds
Author(s): Claudiane Ouellet-Plamondon, Sebastian Scherb, Mathias Köberl and Karl-Christian Thienel
Publication: Symposium Paper
Appears on pages(s): 71-83
Keywords: accelerators, calcined clay, calcium chloride, calorimetry, CSH seeds, in-situ X-ray diffraction, microlimestone, mortar, thermogravimetric analysis
Supplementary cementitious materials (SCM) are needed to reduce the carbon impact of cementitious materials. Especially calcined clay mixtures are a sustainable alternative which is available abundant worldwide. Although strength of binders containing calcined clays may exceed at 28 days the reference cement, there is still one shortcoming: The early strength development is too slow for many applications. In order to overcome this obstacle calcium chloride, microlimestone and CSH seeds were tested in different dosages as hydration accelerator and the most promising dosage was determined by calorimetry and mortar tests. The accelerators increased the amplitude of the maximum heat flow and shortened the time when Qmax occurred compared to the blended binder made with calcined clay. They also acted as a strength accelerator. The reactivity index slightly increased with the calcium chloride and the microlimestone; with CSH seeds it was on the level of the blended binder.