  A Monte Carlo based computer model is presented to comprehend the contrasting
observations of Mazumder et al. [Phys. Rev. Lett. 93, 255704 (2004) and Phys.
Rev. B 72, 224208 (2005)], based on neutron-scattering measurements, on
temporal evolution of effective fractal dimension and characteristic length for
hydration of cement with light and heavy water. In this context, a theoretical
model is also proposed to elucidate the same.
