Microstructural, chemical, mineralogical, and thermal analysis was carried out in a study to use Eraring Power Station (New South Wales, Australia) fly ash as pavement base material. The fly ash was stabilized with cement and lime separately. The effects of cement and lime stabilization were examined in terms of chemical composition, crystalline structures, and hydration products. Unconfined compressive strength of samples was also measured to observe the effect of stabilization over time. The results obtained from cement and lime-stabilized samples showed that the hydration products that account for strength gain of the stabilized fly ash are almost the same for both types of stabilizing agents. The discrepancies between the resulting strengths are due to the proportion and density of these products.