With the increasing demand for sustainable and eco-friendly materials in the twenty-first century, identifying locally sourced substitutes for cement has become crucial for reducing CO2 emissions, minimizing environmental impact, and advancing the principles of circular economy in civil engineering. This study investigates the chemical properties and heavy metals content of biomass ashes derived from agricultural residues in the Vojvodina region of Serbia. The chemical properties of the ashes were analyzed to assess their potential for pozzolanic activity, a key characteristic for their use as supplementary cementitious materials (SCM). Results indicated that several biomass ashes exhibited a favorable chemical composition for pozzolanic reactions, suggesting their potential use in cement-based composites. However, high alkali content was detected, raising concerns about the risk of alkali-silica reaction (ASR) in the hardened cement-based composites. Experimental testing of the ASR mechanism revealed that the expansion due to the reaction between alkalis in the ashes and reactive aggregates remained within acceptable limits. A catalog has been developed to assist potential users in evaluating the biomass ashes for practical applications, featuring comprehensive data on their physical and chemical properties, heavy metal content, alkali-silica reaction (ASR) potential, and environmental impact. This resource provides essential information for assessing their suitability in cement-based composites and other construction materials. These findings underscore the potential of utilizing biomass ashes as a sustainable alternative in cement production, supporting waste valorization, conserving natural resources, and advancing eco-friendly practices in construction, in line with the principles of circular economy and sustainable development.