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

Fourier transform infrared spectroscopy (FTIR) was used to explore the effect of temperature (25, 40 and 65 C) and the presence of amorphous nanosilica (nSA) on the nanostructure of the C-S-H gel generated during tricalcium silicate (C3S) hydration. 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. © 2013 Elsevier Ltd.Funding from the Spanish Ministry of Education and Science (Projects MAT2006-11705 and CONSOLIDER CSD2007-00058), the Agencia Estatal Consejo Superior de Investigaciones Científicas (Grant PIE: 201160E103) and the Regional Government of Madrid (Geomaterials Programme; S2009/MAT-1629) is gratefully acknowledged. Research Fellowship BES-2007-16686 is gratefully acknowledged. The authors wish to thank the CNME of UCM for the use of its TEM.Peer Reviewe