This research investigates the incorporation of the Koradi thermal power plant’s fly ash (FA) into roller-compacted concrete pavements (RCCP). The study focuses on determining the optimum moisture content (OMC), maximum dry density (MDD), and mechanical properties of RCCP mixes with varying FA replacements. Cement was replaced with FA at 25 and 50%. A relationship between the moisture content and dry density was established, indicating a relationship between the FA content and variations in the OMC and MDD. With an increase in the FA content, the OMC rises because of the finer particle size and larger surface area of FA. At the same time, the MDD drops because of the lower specific gravity of FA particles. Compressive, flexural, and splitting tensile strength tests were performed on RCCP samples that have been cured for 7 and 28 days. The findings indicate a significant decline in strength after seven days of curing, especially with higher FA concentration, in contrast to the strength observed after 28 days of curing. This behaviour can be explained by the relatively slower pozzolanic reaction of FA particles compared to the hydration process of cement particles.