Nanosilica is a nano-sized material (1–100 nm) that can be used as a partial substitute for cement to improve the mechanical properties of mortar. This study aims to analyze the effect of nanosilica synthesized by fly ash using the hydrothermal method and variations in curing temperature on the compressive strength of mortar. Nanosilica was used at 12% with curing temperatures of 40°C, 60°C…