Nanosilica is a nano-sized silica that ranges from 1-100 nm and has a function to increase the compressive strength of concrete. Nanosilica can be produced by synthesizing fly ash. The material used in this research is fly ash. This study uses a variation of the ratio between mentanol : precursor, namely 23: 1, 30 : 1, and 37: 1 in units (ml). In this study using microstructure testing to analy…