Abstract This study proposes using sodium silicate-based nano-silica (SS) in cement composites. The effect of the addition of the proposed nano-silica on cement composites was compared to that of conventional ethyl silicate-based nano-silica (ES) and silica fume (SF). This study found that the inclusion of SS in cement composites has mainly two effects on their properties: one is a fast pozzolanic reaction, and the other is a pore-filling effect in a cement matrix. As a result, SS dramatically improves the early-age strength of cement composites by up to 184% and 152%, compared to a control specimen and the specimen with ES inclusion, respectively. Calorimetry, X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) tests were conducted to monitor the effects of these nano-silicas.