The production of asphalt concrete generates asphalt waste dust particles that harm the environment. In this study, asphalt waste dust and fly ash were combined in different ratios to serve as cement replacement material. With replacement ratios of 20–30 wt% asphalt waste dust with fly ash, the maximum strength of a mixed-cement sample meets the industrial requirement after 7 days of curing. Compared to a cement concrete sample, a higher strength than the industrial requirement was achieved after prolonged curing under plastic wrap. This curing condition allows the retention of Ca2+ ions and moisture, contributing to the hydration and pozzolanic reactions in the mixed-cement sample. The strengthened microstructure with the C–S–H phase was clearly seen, while Ca(OH)2 disappeared in the mixed-cement sample. This finding indicates that upcycled asphalt waste dust in a cement-based material is a potential method for utilizing asphalt waste dust in the construction sector.