  Analysis of the mechanical properties of key phases of cementitious systems
during hydration at the nanoscale is vital for a better understanding of the
type and formation of key cement hydration phases. In this work,
nanoindentation technique has been employed to calculate the volume fraction
and elastic modulus of key hydrated phases, calcium silicate hydrate and
calcium hydroxide during the hydration of nanosilica incorporated C3S and
\b{eta}-C2S at certain intervals for 50 days. The comparative analysis shows
\b{eta}-C2S has more dominant low-density calcium silicate hydrate, especially
in the early stage of hydration. While in the case of C3S, the dominant
hydrated phase is high-density calcium silicate hydrate. Furthermore, the
effect of nanosilica incorporation in the matrix of these cement constituents
has also been demonstrated which shows a greater decrease of LD C-S-H and
formation of more HD C-S-H for both C3S and \b{eta}-C2S. By tracking the
mechanical properties of the other hydrated phase, calcium hydroxide, the
pozzolanic activity of nanosilica has also been demonstrated. From the
comparative analysis, it can be observed that the overall mechanical property
of the constitutive phases is fairly similar.
