Durability of GFRP bars subjected to the combined effect of high sustained load and industrial wastewater

This study evaluates the durability of glass fiber-reinforced polymer (GFRP) bars under sustained loading combined with industrial wastewater. Towards this, twenty-four concrete beams (150 × 200 × 1800 mm) were cast, five with steel reinforcement and the rest with GFRP bars. The beam specimens were subjected to sustained loading at 40% of ultimate flexural capacity and immersed in wastewater for 3, 6, and 12 months at 25°C, 40°C, and 60°C. Subsequently, four-point bending tests were conducted to assess flexural behavior, including load-displacement response, ultimate capacity, deflection, cracking, and failure modes. Concurrently, bare GFRP bars exposed under identical conditions to assess degradation of the mechanical properties. Results showed up to 12% capacity loss in steel-reinforced beams, whereas GFRP-reinforced beams maintained superior performance. Bare GFRP bars exhibited strength and stiffness reductions of 6% and 9%, respectively, after 12 months at 60°C. Experimental findings were compared with analytical models available in design codes. • Longevity of GFRP rebars was assess under industrial waste water and sustained load. • Deteriorating process was accelerated by elevating conditioning temperature. • Test specimens include both reinforced beams and bare GFRP bars. • Results indicated enhanced performance of GFRP reinforced beams. • Tensile properties of bare GFRP rebars were reduced after conditioning.