The bond between concrete and steel rebar is one of the most crucial parameters in the construction of reinforced concrete structures. The load-bearing capacity and serviceability of these structures depend heavily on bond strength. The rib pattern of the rebar plays a significant role in enhancing bond behaviour. The impact of different rebar patterns on bond studies in the concrete mix is found to be limited. In the study, six concrete mixes were prepared and tested. Three of these mixes incorporated fly ash in varied amounts to partially replace cement, while the other three mixes had no fly ash. Three different rib patterns of steel bars were embedded into these six grades of concrete. The pull-out tests were used to assess the bond strengths of various combinations in accordance with RILEM recommendations. The findings show that the ribs in rebars significantly increase mechanical interlocking whereas the presence of fly ash improves chemical adhesion in bond behaviour. Particularly, pattern 2 rebar (transverse rib thickness, 0.797 mm; transverse rib width, 2.06 mm; rib spacing (inner to inner), 6.428 mm; longitudinal rib thickness, 1.04 mm; longitudinal rib width, 2.312 mm; rib inclination angle, 66.39o; nominal diameter, 16 mm; length of transverse rib, 25 mm) exhibited notably superior bond strength, reaching a maximum of 17.21 MPa in M30 grade concrete in which 95 kg/m³ of fly ash was used as a replacement for cement.