Digital construction has recently become the subject of very rapidly growing research activities all over the world. In this regard, our current research demonstrates the possibility of using high volume fly ash mortar, modified with micro silica for 3D concrete printing application. To assess the effect of the micro silica on rheological performance, a rotational rheometer was used to measure yield stress, viscosity and reversible stiffening behavior of ternary blends of fly ash–cement–micro silica. Since, the disposal of fly ash from coal power plants has increased rapidly due to the feed-in tariff established by the government, this research will pave a way to utilize high volume of fly ash for digital construction application.