2023 Volume 77 Issue 1 Pages 44-52
In this paper, 1H-NMR Relaxometry is applied to carbonation phase and analyzes changes of chemically bound water content, mobile water content, and total water content in hardened cement paste with the progress of carbonation. The results showed that calcium hydroxide and C-S-H were carbonated at 20℃ and 85％RH. From the measurement of transverse relaxation time T2 by CPMG method, it was confirmed that the transverse relaxation time of Interlayer and Gel pore increased with carbonation. There was a positive correlation between carbonation degree of calcium hydroxide calculated by thermogravimetric/differential thermal analysis and decreasing of chemically bound water measured by Solid echo method, confirming that chemically bound water in calcium hydroxide changed to mobile water due to carbonation. Regarding mobile water, the water content of Gel pore increased and that of Interlayer decreased in C-S-H during the initial stage of carbonation.
