Quasielastic neutron scattering (QENS) has been used to investigate the single-particle dynamics of interfacial water in dicalcium silicate (C2S)/water paste. Our previous neutron-scattering studies on interfacial water have focused attention on the translational dynamics of the center of mass of water molecules. In this paper, we have collected QENS data on a wider range of wave-vector transfer so that both translational and rotational motions of water molecules are detected. The data have been analyzed by models for translation and rotation we recently proposed for supercooled water. The evolution of the parameters describing the relaxational dynamics of water embedded in the C2S matrix is given at temperature T=303 K as a function of the curing time.