Evolution of ordinary Portland cement hydration with admixtures by spectroscopic techniques

The various waterproofing admixtures may prevent water from penetrating concrete in different ways, but primarily by rendering it hydrophobic. Spectroscopic techniques have proved to be the appropriate tools for studying cement hydration in the presence of different admixtures. A combination of Fourier Transform-Raman and ²⁹ Si nuclear magnetic resonance (NMR) spectroscopy were used here to monitor OPC hydration and C-S-H gel formation with two different waterproofing admixtures. The Q¹/Q⁰ ratio was determined with the former technique to evaluate the influence of the waterproofing substances on C-S-H gel formation rate and intensity, whereas ²⁹Si NMR was employed to establish the relative amount of C-S-H gel formed at different hydration times as well as to calculate the main chain length.