Abstract
Coal bottom ash (CBA) is increasingly investigated as a replacement for natural fine aggregates in concrete, addressing resource depletion and waste management. However, bibliometric analysis focused specifically on CBA as fine aggregate remains limited. This study integrates bibliometric mapping with a synthesis of experimental evidence to evaluate 147 publications from 2015 to 2025. Together, these perspectives connect research trends with performance outcomes and help explain inconsistencies observed in CBA-concrete behavior. Bibliometric results indicate rapid growth in studies emphasizing mechanical performance, particularly compressive strength, while sustainability and methodological issues remain underexplored. Experimental evidence indicates that CBA can partially or fully replace sand, with replacement levels around 20–25% consistently yielding acceptable mechanical performance across multiple studies, though higher replacement levels are achievable under specific conditions. Key research gaps are identified, including inconsistent particle size grading, variable moisture conditioning protocols, and unclear replacement metrics. Such variation in experimental designs limits comparability across studies and contributes to conflicting conclusions. Integrating bibliometric and experimental perspectives highlights the need for more standardized experimental practices to support the sustainable use of CBA in concrete.