Composition and microstructural changes in an aged cement pastes upon two heating-cooling regimes, as studied by thermal analysis and X-ray diffraction

作者：Sabeur Hassen^*; Platret Gerard; Vincent Julien

来源：Journal of Thermal Analysis and Calorimetry, 2016, 126(3): 1023-1043.

DOI：10.1007/s10973-016-5639-8

• High temperature
• Cooling regime
• Cement paste
• Thermal analysis
• X-ray diffraction

This paper studies the microstructural changes in a 2-year-old cement paste heated up to various temperature up to 1000 degrees C in steps of 100 degrees C for a constant period of 6 h by TG/DTG and XRD. Two cooling regimes are applied: air-and desiccator-cooling regime. The impact of ageing on the microstructure of the heated specimens is analysed by comparison with a cement paste cured at 28 days. The result shows higher amounts of portlandite and carbonate calcium for the aged cement paste. The new portlandite formed during cooling continues to exist until the 1000 degrees C temperature plateau. The decomposition of the latter portlandite induces higher quantities of lime, and then higher mass loss in the case of the air-cooling regime compared to the desiccator one. Nevertheless, the XRD shows that the peak's intensity of lime is lower in the case of air-cooling regime. The CSH dehydration to beta-C2S and C3S becomes significant above 600 degrees C and the corresponding rate increases with increasing temperature. An increase in the total mass loss and in the crystallinity at 900 and 1000 degrees C, compared to 800 degrees C, is noted.

• 出版日期2016-12