This study predicts the ultimate expansion of mortar bars (UME) due to alkali-silica reactivity (ASR). The experimental expansión data utilized in this study were obtained from two previous studies. The experimental expansion data over the test duration of 28 days was fitted with the existing proposed decay model to predict the UME and time required to reach at 50%, 75% and 90% of UME. Finally, aggregates susceptible to alkali-silica reactivity were determined based on the existing proposed limit of UME, and were compared with the results obtained by the aggregate geology and expansion limits at the test durations of 14 and 28 days. The study showed that the ultimate mortar expansion and time required reaching various percentages of UME varied on aggregate mineralogy.