Author(s): Parisa Khodadadi

Abstract: This study presents an experimental investigation on the mechanical performance, bond behavior, and flexural response of basalt fiber-reinforced polymer (BFRP) bars for structural strengthening applications. The research aimed to evaluate the tensile, bond, and flexural characteristics of BFRP-reinforced concrete members under different environmental exposures, including alkaline, freeze-thaw, and seawater conditions. BFRP bars of ribbed and sand-coated types were embedded in concrete beams and cubes to assess tensile strength, bond-slip performance, and flexural capacity compared to conventional steel reinforcement. The results demonstrated that BFRP bars possess high tensile strength (approximately 1000 MPa) and an elastic modulus of 50 GPa, with only moderate strength reductions under adverse exposure conditions. Sand-coated bars consistently achieved higher bond strength (10-12 MPa) and smaller slip at peak load than ribbed bars, attributed to improved interfacial adhesion and frictional resistance. Flexural testing of BFRP-reinforced beams revealed enhanced load-bearing capacity exceeding steel controls by up to 30% although with higher service deflections and crack widths due to lower stiffness. Statistical analyses using one-way ANOVA confirmed significant effects of exposure condition and surface treatment on both bond and flexural responses. The estimated bond-dependent coefficient (kbk_bkb) ranged between 0.76 and 0.84, aligning with current design recommendations. Overall, the study establishes that BFRP bars, particularly with sand-coated surfaces, can effectively replace or supplement steel reinforcement in corrosive or durability-critical environments. However, design modifications are necessary to address serviceability and environmental degradation effects. The findings provide a scientific basis for refining existing FRP design codes and support the broader use of BFRP reinforcement in sustainable structural engineering applications.

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