TY - JOUR

T1 - Influence of low-pressure treatment on the morphological and compositional stability of microscopic ettringite

AU - Kißling, Patrick A.

AU - Lübkemann, Franziska

AU - von Bronk, Tabea

AU - Cotardo, Dario

AU - Lei, Lei

AU - Feldhoff, Armin

AU - Lohaus, Ludger

AU - Haist, Michael

AU - Bigall, Nadja C.

N1 - Funding Information: Funding: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, projects BI 1708/5-1 and LO 751/26-1 in the framework of SPP 2005 priority program ‘Opus Fluidum Futurum–Rheology of reactive, multiscale, multiphase construction materials’ [41], as well as by the project BI 1708/4-1. In addition, the project leading to these results has received funding in part from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 714429).

PY - 2021/5/21

Y1 - 2021/5/21

N2 - The impact of low-pressure treatment on the crystal structure, morphology, and chemical composition of ettringite, due to their major importance with respect to processability (i.a., dry-ing conditions) and to the analysis of ettringite-containing samples, is examined utilizing X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and environmental scanning electron microscopy. Synthetic ettringite was treated for various durations (5 min up to 72 h) and at two different levels of low-pressure (4.0 mbar and 60 µbar). Evaluation showed a correlation between the procedural parameters (time and pressure), the chemical composition, and the morphology of ettringite. The experiments reveal that, when exposed to 4 mbar pressure, nearly no changes occur in the ettringite’s morphology, whereas the crystals undergo swelling and slight deformations at very low pressures (60 µbar and 35.3 nbar), which is attributed to the loss of bound water and the partial transformation from ettringite to quicklime, anhydrite, and calcium aluminate. Furthermore, the strongly dehydrated ettringite shows the same morphology.

AB - The impact of low-pressure treatment on the crystal structure, morphology, and chemical composition of ettringite, due to their major importance with respect to processability (i.a., dry-ing conditions) and to the analysis of ettringite-containing samples, is examined utilizing X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and environmental scanning electron microscopy. Synthetic ettringite was treated for various durations (5 min up to 72 h) and at two different levels of low-pressure (4.0 mbar and 60 µbar). Evaluation showed a correlation between the procedural parameters (time and pressure), the chemical composition, and the morphology of ettringite. The experiments reveal that, when exposed to 4 mbar pressure, nearly no changes occur in the ettringite’s morphology, whereas the crystals undergo swelling and slight deformations at very low pressures (60 µbar and 35.3 nbar), which is attributed to the loss of bound water and the partial transformation from ettringite to quicklime, anhydrite, and calcium aluminate. Furthermore, the strongly dehydrated ettringite shows the same morphology.

KW - Chemical composition

KW - Ettringite

KW - Low-pressure

KW - Morphology

KW - Pawley fit

UR - http://www.scopus.com/inward/record.url?scp=85106968026&partnerID=8YFLogxK

U2 - 10.3390/ma14112720

DO - 10.3390/ma14112720

M3 - Article

AN - SCOPUS:85106968026

VL - 14

JO - Materials

JF - Materials

SN - 1996-1944

IS - 11

M1 - 2720

ER -