INVESTIGATION OF HYDRATION AND POZZOLANIC REACTION IN REACTIVE POWDERCONCRETE (RPC) USING SI-29 NMR

Hydration of RPC (Reactive Powder Concrete) and pozzolanic reaction we re 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 velo city).... Two RPC formulations were tested. Samples having undergone h eat treatment at temperatures between 20 degrees C and 250 degrees C w ere investigated in order to gain a better understanding of the influe nce of temperature on hydration and pozzolanic activity. It was shown that silica fume consumption was highly dependent on heat treatment te mperature and duration. Crushed quartz reactivity was also clearly dem onstrated. It was proved to be dependent on heat treatment temperature and duration. Q(3) peaks attributed to the presence of a crystal hydr ate, xonotlite were identified at 250 degrees C. Microstructural chang es in hydrates structure were also observed. Average C-S-H chain lengt h was shown to increase with increasing heat treatment temperature.