Investigationinto the reuse of industrial by-products for producing eco-friendly construction materials has still received much attention from research scholars around the world. This study investigates the influence of fly ash (FA) content as a cement replacement on the fresh and hardened properties of cement paste. FA was used to substitute Portland cement at different levels of 0 –80% by weight. Results show that,increasing the FA content resulted in better flowability and longer setting time of the mixtures. However, the samples with higher FA content exhibited lower compressive strength and higher water absorption. Importantly, theinclusion of FA reduced the drying shrinkage of the hardened paste.At 28 days, the 80% FA samples had values of compressive strength, water absorption, and change in length of about 45.2, 136.82, and 55.7% of the corresponding values of the FA-free sample. Thus, the quantity of FA should be selected based on specific application purposes.