Mechanical Performance of M25 concrete incorporating basalt and limestone as coarse aggregate replacements

This study systematically evaluates the influence of progressively replacing natural coarse aggregates with basalt, supplemented by a limited proportion of limestone, across a range of substitution levels. A comprehensive analysis of mechanical performance demonstrates that the mixture composed entirely of basalt achieves the highest strength and overall structural efficiency, while the hybrid composition containing 75% basalt and 25% limestone also delivers notably strong performance. These findings underscore the superior mechanical characteristics of basalt relative to conventional aggregates and confirm its suitability for demanding structural concrete applications. In addition to quantifying strength improvements, the results provide deeper insight into the synergistic behavior between basalt and limestone within the concrete matrix, particularly in terms of load transfer mechanisms, particle interlocking, and overall matrix densification. This enhanced understanding contributes to the broader body of knowledge on aggregate optimization in concrete technology. From a practical perspective, the study offers valuable guidance for engineers and practitioners by identifying optimal mixture proportions that balance performance and material efficiency. Furthermore, the adoption of basalt, especially when locally available, presents a viable pathway toward producing stronger, more durable, and environmentally sustainable concrete, thereby supporting ongoing efforts to reduce the environmental footprint of construction materials.