AbstractIn fiber-reinforced cementitious composites, the fiber/matrix interfacial bonding is a governing factor for bridging cracks, load transfer, and toughening mechanisms. Basalt fiber pellets (BFP) are a novel form of macrofibers consisting of basalt fiber strands encapsulated by a polymeric resin, with textured microgrooves, which can be used to produce high-performance fiber-reinforced cementitious composites (HPFRCC). Hence, the current study focused on the synergetic evaluation of the flexural performance and single pellet pull-out of BFP in homogenized nano-modified [nano-silica (NS); nano-crystalline cellulose (NCC)] cementitious matrices, without/with micro [polyvinyl alcohol fibers (PVA)], or nano-fibers [nano-fibrillated cellulose (NFC)]. Integrated experimental and modeling studies were conducted to evaluate the effect of BFP interfacial bonding with various nano-modified cementitious matrices. Key results showed that NS-modified matrices led to improvement by 17% and 5%, respectively, in terms of bonding strength with BFP and debonding energy, compared with matrices comprising NCC. Reduction of BFP interfacial bond strength and debonding energy by 11% and 10% was observed for cementitious matrices comprising NCC and reinforced with NFC, relative to mixture G-NCC. Conversely, using PVA fibers in matrices comprising NS led to noticeable enhancement of bonding with BFP (highest bonding strength and debonding energy), which suggests their promising potential for field applications requiring HPFRCC.