Coal fly ash (CFA) and coal bottom ash (CBA) are coal combustion's primary solid waste products. This solid waste management is a substantial challenge for power plants and local authorities. In order to apply coal ash as a pavement base material, the relationship of the mixture's mechanical properties with structural design pa-rameters for pavement design and analysis must be explored. No study has investigated the mechanical behavior of the 100% coal ash cement stabilized material (CACSM) as a pavement base layer. Therefore, this study aimed to investigate the structural layer coefficient of CACSM used in the American Association of State Highway and Transportation Officials (AASHTO) 1993 pavement design guide. The study consisted of laboratory material characterization and field evaluation. The mechanical property test revealed that CACSM has a self-healing ability; coal ash appeared to influence the secondary curing of the specimens significantly. Strength towards the ends of stage I and stage II showed the influence of high pozzolanic on the CACSM, which resulted in improved long-term performance. The layer coefficients of the locations in the field test ranged from 0.22 to 0.24. By contrast, for the granular base and cement-treated base, these values were 0.07 to 0.14 and 0.17-0.20, respectively. The study findings show that CACSM as a pavement base is a viable solution that can help develop transportation infrastructure with enhanced concrete durability and lower carbon footprint emissions.