Investigation of hydration and pozzolanic reaction in reactive powder concrete (RPC) using Si-29 NMR

Hydration of RPC (Reactive Powder Concrete) and pozzolanic reaction were studied by Si-29 NMR using SPE/MAS technique. Industrial cement and materials (silica fume, crushed quartz) constitutive of RPC imposed a careful study of spectra acquisition (relaxation times, spinning velocity).... Two RPC formulations were tested. Samples having undergone heat treatment at temperatures between 20 degrees C and 250 degrees C were investigated in order to gain a better understanding of the influence of temperature on hydration and pozzolanic activity. It was shown that silica fume consumption was highly dependent on heat treatment temperature and duration. Crushed quartz reactivity was also clearly demonstrated. It was proved to be dependent on heat treatment temperature and duration. Q(3) peaks attributed to the presence of a crystal hydrate, xonotlite were identified at 250 degrees C. Microstructural changes in hydrates structure were also observed. Average C-S-H chain length was shown to increase with increasing heat treatment temperature.