<p>Civil engineering practices are being directed towards a sustainable approach by incorporating the use of recycled waste aggregates. However, structural safety still remains the utmost concern. Under seismic loading, the most vulnerable region of a building is its beam-column joints. Recent innovative practices point towards using non-identical concrete mixes in the three elements of the joint region in a frame structure: beam, column, and joint. In the present study, a thorough in-depth investigation is carried out to assess the seismic performance of beam-column joints by replacing traditional coarse aggregates (stone chips and brickbat) in the concrete of beam-column joints. The replacements are done by using recycled wastes (recycled concrete and steel slag) as substitutes for conventional coarse aggregates in each of the three elements. The performance of the specimens using non-identical concrete mix cast with recycled waste aggregates is compared against the control specimens made entirely of traditional coarse aggregate concrete. Their performance is also compared against specimens using non-identical concrete mixes in the three elements of a joint but using conventional coarse aggregates in each of the mixes. The outcomes of the experiment reveal that replacement with non-identical concrete mixes made of recycled materials in joints increased the energy dissipation capacity and ductility. Furthermore, results indicated a decrease in the percentage loss of stiffness degradation of the specimens. These findings provide an experimental and scientific basis for the practical application of non-identical mixes of steel slag aggregate and recycled aggregate concrete in the elements of a joint.</p>