This document summarizes an experimental study on the use of fly ash as a partial replacement for cement in concrete. Fly ash is a byproduct of coal combustion that can be used to reduce the environmental impacts of coal use and lower the cost of concrete production. The study tested concrete mixtures where cement was replaced with fly ash at levels of 0%, 5%, 10%, 15%, and 20% by weight. The compressive strength of concrete cubes was tested at 7 and 28 days. The results showed that compressive strength generally increased as the level of fly ash replacement increased up to 20%, indicating that fly ash can improve concrete strength properties while providing environmental and economic benefits.