Cement has been used for centuries as a cost-effective construction material, as well as for the conditioning of low-level radioactive waste. The interaction of water with calcium silicate hydrate (the main component of cement paste, C-S-H) is one of the prime factors for controlling the stability of the cement paste in the environment. However, much of the material science of cement hydration, including the bonding and interaction of water with C-S-H, remains unknown. Here we used high-resolution quasi-elastic neutron scattering to investigate the water dynamics on cement pastes hydrated for more than 28 days with different levels of hydration on the nanosecond time scale.