Nano-silica accelerates C3S hydration in 3 d but reduces hydration rate after 3 d.
Nano-silica increases C–S–H content but reduces growth rate of C–S–H after 3 d.
Denser C–S–H with low Ca/Si ratio is formed in the presence of nano-silica.
Nano-silica reduces the total porosity of C3S and optimizes the pore structure.