Abstract
This report has two purposes：one is to ascertain the relationship between the dynamics of water molecular in Calcium Silicate Hydrate（C-S-H）which is the main component of harden cement and curing conditions such as relative humidity（RH）. The other is to verify the availability of 2H-NMR for cementisious materials comparing the result of differential scanning calorimetry（DSC）. For the first purpose, deuterium（2H or D）quadrupolar echo NMR spectra, longitudinal relaxation time T1 and rotational correlation time τc were obtained from white portland cement and D2O mixture with different curing conditions such as RH11, 33, 60 and 98％ for 91days. 2H-NMR spectra show two signals：a sharp central signal which contributes ‘mobile’ deuterium and the outer symmetric signal which contributes ‘rigid’ deuterium. The water located on the surface of pore in C-S-H can be divided into two layers by analyzing center signal：one is the ‘First layer’ which is strongly absorbed on the surface of pore and consists of one molecular layer. The other is ‘Transition layer’ which is semi-absorbed layer and consists of several molecular layers. The absorbed water thickness of water molecular on the surface of pore can be calculated by the fraction of First layer and Transition layer. These calculated thicknesses of water layer show water state and structural change of C-S-H at each RH condition. Furthermore, the result elucidate that the sensitivity of 2H NMR is quite high because mobility of water molecular oflow RH samples such as RH11 and 33％ can be analyzed even though these samples do not show any DSC signals,.
