Mechanical Performance of Fly Ash Blended Cement Mortar: An Experimental Investigation

The increasing environmental burden associated with ordinary Portland cement (OPC) production has encouraged the exploration of supplementary cementitious materials for sustainable construction. Fly ash, a by product of coal based thermal power plants, has shown considerable potential as a partial replacement for cement due to its pozzolanic characteristics. This study experimentally evaluates the compressive strength development of cement mortar incorporating varying proportions of fly ash as a cement substitute. Mortar specimens were prepared with fly ash replacement levels ranging from 15% to 50% by weight of cement, while a conventional OPC mortar served as the control mix. Standard cube specimens of size 70.6 mm × 70.6 mm × 70.6 mm were cast and tested for compressive strength at curing ages of 3, 7, 14, 21, and 28 days. The results indicate that mortar containing 30% fly ash achieved optimum performance, attaining nearly 94% of the compressive strength of the control mix at 28 days. The findings confirm that fly ash can be effectively used as a partial cement replacement in mortar without significant loss of strength, contributing to environmentally responsible construction practices.