White cement pastes were hydrated in the presence or absence of amorphous nanosilica (nSA) and cured at 25 or 65 degrees C. The findings showed that at the higher curing temperature the initial belite hydration rate rose substantially and that this effect was more accentuated in the pastes containing nSA. The C S H gel formed in the presence of nSA was more uniform and had a consistently longer mean chain length (MCL) than in the gels formed in the absence of the addition. Moreover, the C-S-H gel formed in nSA-bearing paste cured at the higher temperature had a longer MCL and a higher Al3+ uptake than the gels in the other pastes studied. Lastly, at 65 degrees C, the presence of nSA stabilized ettringite formation during the first 28 days of paste hydration; while no calcium hemicarboaluminate, which was the sole crystalline aluminate hydrate identified in the unblended pastes, was detected in the nSA-containing pastes.