FTIR study of the effect of temperature and nanosilica on the nano structure of C-S-H gel formed by hydrating tricalcium silicate

Rising temperatures were shown to modify the nanostructure of C-S-H gel. The bands at around 1076 cm−1, 909 cm−1 and 540 cm−1 that appeared on the FTIR spectrum for C3S paste with rising temperatures were attributed to the formation a jennite-like structure. Moreover, irrespective of temperature, as the reaction progressed, the initial tobermorite-like C-S-H gel changed to a jennite-like structure. With the addition of nSA, the band generated at 960-970 cm−1 appeared from the first day of hydration, an indication that nanosilica accelerates C3S hydration. The presence of nSA induced no narrowing of the bands at 1076 cm−1 or 909 cm−1 at any curing time, a sign that these gels had a smaller proportion of jennite-like species than the gels in the nSA-free pastes. Finally, compositional date of C-S-H was provides.