Chemical and mineralogical characteristics of carbonated and uncarbonated cement pastes subjected to high temperatures
Journal article, 2021

The fire-resistance of carbonated concrete under high temperatures is significant due to its direct exposure during an accidental fire. To evaluate the carbonation effect on fire-resistance of concrete, the chemical and mineralogical changes of uncarbonated and carbonated cement pastes subjected to high temperatures were thoroughly investigated in this research by employing micro-measurement methods including thermal-gravimetric analysis (TGA), X-ray diffraction (XRD) and Si nuclear magnetic resonance ( Si NMR). Uncarbonated cement paste results showed the decomposition of portlandite at 400 °C with the formation of lime, whilst the depolymerization of C–S–H happened simultaneously to generate monomeric silicon tetrahedron. Above 720 °C, all the C–S–H depolymerized to crystalline C S. Carbonated cement pastes on the other hand showed that amorphous calcium carbonate and part of vaterite decomposed between the range of 400–600 °C, while the rest of the vaterite and calcite were decomposed at 600–720 °C. The individual content of calcium carbonate polymorph could not be obtained using a TGA curve. Besides, the calcium-modified silicate gel was significantly decomposed at 500 °C and completely depolymerized to crystalline C S at 950 °C. In summary, carbonated pastes show better resistance to high temperatures with its heat absorption capacity 3.3 times as high as the uncarbonated sample, which delays the temperature development in the inner layer. Therefore, a reasonable carbonation process could help to improve the fire resistance of concrete to some extent.

Calcium-modified silica gel

Fire resistance

Cement paste



High temperature


Yongqiang Li

China Earthquake Administration

Shenzhen University

Tangwei Mi

Shenzhen University

W. Liu

Shenzhen University

Zhijun Dong

ShenZhen Institute of Information Technology

Biqin Dong

Shenzhen University

Luping Tang

Chalmers, Architecture and Civil Engineering, Building Technology

F. Xing

Shenzhen University

China Earthquake Administration

Composites Part B: Engineering

1359-8368 (ISSN)

Vol. 216 108861

Subject Categories

Inorganic Chemistry


Materials Chemistry



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