Exactly how one can prepared the cement sample for XRD and TG/DTA? how can stop the hydration of cement?
Please check:
Article Report of TC 238-SCM: hydration stoppage methods for phase a...
Article RILEM TC-238 SCM recommendation on hydration stoppage by sol...
https://www.crcpress.com/A-Practical-Guide-to-Microstructural-Analysis-of-Cementitious-Materials/Scrivener-Snellings-Lothenbach/p/book/9781138747234
Please check:
Article Report of TC 238-SCM: hydration stoppage methods for phase a...
Article RILEM TC-238 SCM recommendation on hydration stoppage by sol...
https://www.crcpress.com/A-Practical-Guide-to-Microstructural-Analysis-of-Cementitious-Materials/Scrivener-Snellings-Lothenbach/p/book/9781138747234
The most convenient and easy way to do so is by drying your samples under a high temperature (ranges between 105 and 110 °C) for 48 hours. Remember to test them under XRD straight after the drying process so cement will not absorb moisture !
Sorry to say this, but the stoppage method suggested in the previous answer should not be used at all. Drying at 105°C will cause partial dehydration especially of ettringite and the AFm phases. The result will be that you cannot identify them by XRD anymore. The recommended practise is hydration stoppage by solvent exchange using isopropanol as highlighted in the documents I provided above. There you will find also results of a round robin test comparing solvent exchange with drying at 105°C.
Would you think freeze drying is also considered as a relevant method for hydration stoppage (wrt. its convenience and fast drying) Frank Winnefeld? Thanks.
Freeze drying can be used for certain applications, as it has the advantage that contact to CO2 (and thus carbonation) is limited. However, a part of the chemically bound water from C-S-H and AFm and AFt phases will be removed (depending on the exact drying conditions). As a result, e.g. ettringite might not be detected by XRD anymore as shown e.g. in the RILEM TC SCM round robin test on hydration stoppage. Please consult the above mentioned papers and the book for further details.
Please study paper "Quantitative characterization of pore morphology in hardened cement paste via SEM-BSE image analysis by Kai Lyu ... " section 2.3.1. Sample preparation.
I think that booking the XRD machine and doing the experiment at 28-day is the best.
I usually use acetone or ethanol to stop the hydration process before the XRD.
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