Building demolition waste has a significant Environmental impact (EI) including waste generation, CO₂ emissions and land use alteration. Recycling and reutilizing these materials possess the potential to alleviate the strain on landfills and diminish the dependence on natural resources. Recycled concrete aggregates (RCA) from demolished structures were used in producing concrete masonry blocks (CMBs). The mechanical characteristics of the CMB were evaluated and life cycle assessment (LCA) calculations were conducted to assess the environmental implications of the materials employed in the manufacturing process of CMB. Incorporating 25% RCA into CMB resulted in a 1.8% decrease in compressive strength (CS). Subsequently, as the RCA content increased to 50%, 75%, and 100%, CS exhibited a consistent decreasing pattern, with reductions of 2.9%, 10.9%, and 16.4%, respectively. Ultrasonic pulse velocity (UPV) results showed a replicating trend in the CS. Substituting RCA with natural aggregates reduced carbon emissions by 10% but high volumes of RCA were ineffective in reducing emissions due to their adverse impact on CS. When comparing the EI of coarse aggregates only, RCA shows 84% less impact than natural coarse aggregates.