کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1457343 | 989255 | 2009 | 7 صفحه PDF | دانلود رایگان |
Diffuse Reflectance Infrared DR-FTIR spectroscopy is employed to monitor chemical transformations in pastes of Portland limestone cement. To obtain a sufficient time resolution a freeze-dry procedure is used to instantaneously ceasing the hydration process. Rapid re-crystallization of sulphates is observed during the first 15 s, and appears to be complete after ~ 30 min. After ~ 60 min, spectroscopic signatures of polymerizing silica start to emerge. A hump at 970–1100 cm− 1 in conjunction with increasing intensity in the water bending mode region at 1500–1700 cm− 1 is indicative of the formation of Calcium Silicate Hydrate, C-S-H. Simultaneously with the development of the C-S-H signatures, a dip feature develops at 800–970 cm− 1, reflecting the dissolution of Alite, C3S. Setting times, 180 (initial) and 240 (final) minutes, are determined by the Vicat technique. Combining DR-FTIR, SEM and Vicat measurements it is concluded that the setting is caused by inter-particle coalescence of C-S-H.
Journal: Cement and Concrete Research - Volume 39, Issue 5, May 2009, Pages 433–439