Low pH exposure of hydrated cement leads to its gradual degradation by the process of leaching, which is the migration of Calcium ions to the external solution. This action increases the pore connectivity of C-SH gel and changes its equilibrium Ca/Si ratio. The effect of nanomaterials such as reduced graphene oxide (rGO), dry aluminium oxide nanopowder (n-Al2O3) and colloidal silicon dioxide nanoparticles (n-SiO2) on the Calcium leaching of cement paste was investigated in this paper. The limewater cured cement paste mixes incorporating the nanomaterials were immersed in 0.5 M HNO3 solution for 56 days. The leached samples were characterized using FTIR, OM, SEM and X-ray CT. © 2016 International Committee of the SCMT conferences. All rights reserved.