EAS/PSE Seminar Series
Examining the microstructural control of the stress sensitivity of dehydration kinetics in rocks
Dr Christoph Schrank
May 19th, 2020
In previous fast in-situ synchrotron small- and wide-angle scattering (SAXS/WAXS) experiments, we showed, for the first time, that gypsum rock with randomly oriented grains dehydrates to hemihydrate twice as fast under an elastic differential pre-stress of ca. 5 MPa. We predicted that grain-scale internal stresses caused by the pre-stress load and the random microstructure explain this surprising finding. Here, we report an experimental test of this hypothesis. Using in-situ SAXS/WAXS, we examined the effect of pre-stress on the dehydration kinetics of satin spar, a natural fibrous gypsum rock with a strong crystallographically preferred orientation. The experimental results confirm our prediction: the fibrous gypsum rock displays negligible stress sensitivity of dehydration kinetics. Other new insights into the important role of local microstructure and crystallographically controlled cracks for dehydration progress are also presented.
|Start Date:||19/05/2022 [add to calendar]|