Assessment of compositional changes of carbonated cement pastes subjected to high temperatures using in-situ Raman mapping and XPS

TY - JOUR

T1 - Assessment of compositional changes of carbonated cement pastes subjected to high temperatures using in-situ Raman mapping and XPS

AU - Li, Yongqiang

AU - Mi, Tangwei

AU - Ding, Xiaobo

AU - Liu, Wei

AU - Dong, Biqin

AU - Dong, Zhijun

AU - Tang, Luping

AU - Xing, Feng

N1 - Copyright: © 2021 Elsevier Ltd. All rights reserved.

PY - 2022/1

Y1 - 2022/1

N2 - This paper presents a new method for assessing the compositional changes of carbonated cement pastes subjected to high temperatures. In this new method, in-situ Raman mapping combined with X-ray photoelectron spectroscopy (XPS) was used to monitor the phase transformation in carbonated cement pastes subjected to various high temperatures from 30 to 950 °C. Two kinds of carbonated areas, i.e., vaterite dominated and calcite dominated, were found in the in-situ Raman measurements. With the elevation in temperature, most of the vaterite was converted to calcite at 500 °C and completely decomposed at 600 °C, while the decomposition of calcite started at 600 °C and finished at 720 °C. Meanwhile, the depolymerization of the calcium modified silica gel to the silicate phases with a lower degree of polymerization was initiated at 500 °C, which led to the crystallization of β-C2S at 600 °C. The generation of β-C2S was found to increase with the elevation in temperature and became the dominant phase at 950 °C. In conclusion, the high temperature could affect the stability of carbonated cement pastes at 500 °C and above. The in-situ Raman mapping measurement has provided an extraordinary view of the spatial distribution of interesting phases subjected to high temperatures in a non-destructive way, which should be more consistent with the true condition in the material.

AB - This paper presents a new method for assessing the compositional changes of carbonated cement pastes subjected to high temperatures. In this new method, in-situ Raman mapping combined with X-ray photoelectron spectroscopy (XPS) was used to monitor the phase transformation in carbonated cement pastes subjected to various high temperatures from 30 to 950 °C. Two kinds of carbonated areas, i.e., vaterite dominated and calcite dominated, were found in the in-situ Raman measurements. With the elevation in temperature, most of the vaterite was converted to calcite at 500 °C and completely decomposed at 600 °C, while the decomposition of calcite started at 600 °C and finished at 720 °C. Meanwhile, the depolymerization of the calcium modified silica gel to the silicate phases with a lower degree of polymerization was initiated at 500 °C, which led to the crystallization of β-C2S at 600 °C. The generation of β-C2S was found to increase with the elevation in temperature and became the dominant phase at 950 °C. In conclusion, the high temperature could affect the stability of carbonated cement pastes at 500 °C and above. The in-situ Raman mapping measurement has provided an extraordinary view of the spatial distribution of interesting phases subjected to high temperatures in a non-destructive way, which should be more consistent with the true condition in the material.

KW - Carbonation

KW - Cement pastes

KW - High temperature

KW - In-situ Raman mapping

KW - XPS

UR - https://www.scopus.com/pages/publications/85122614114

U2 - 10.1016/j.jobe.2021.103454

DO - 10.1016/j.jobe.2021.103454

M3 - Article

AN - SCOPUS:85122614114

SN - 2352-7102

VL - 45

JO - Journal of Building Engineering

JF - Journal of Building Engineering

M1 - 103454

ER -