These data are supplemental data that include digital holographic microscopy measurements of nanoscale surface topography changes occurring during the dissolution of beta-dicalcium silicate in water and in water-ethanol mixtures. The dissolution flux in flowing solutions depends on the water activity to an empirically determined power of 1.7. The heterogeneous distribution of reactive surface sites (e.g., crystalline defects) at the surface leads to a distribution of local fluxes. Accounting for the nominally non-reactive and slowly reactive surface sites, the median of the macroscopic dissolution flux distribution is -0.64 umol m-2 s-1. Ex situ X-ray photoelectron spectroscopy indicates that the calcium-to-silicon ratio near the surface decreases by about 10 % after dissolution has taken place for more than 30 minutes.