Behavior of SCC One-Way Bridge Deck Slabs Reinforced with Basalt FRP Bars under Concentrated Wheel Loads

Fiber-reinforced polymer (FRP) bars have gained significant attention in fabricating bridge deck slabs—particularly in harsh environments—owing to their superior corrosion resistance. Because of the comparatively low modulus of elasticity of FRP bars, controlling deflection and crack width under service conditions is a key concern in flexural design. This investigation evaluated the effect of fiber addition on the serviceability of one-way bridge deck slabs made of self-consolidating concrete (SCC) reinforced with basalt fiber–reinforced polymer (BFRP) bars. Six full-scale one-way bridge deck slabs—representing typical North American slab-on-girder bridges—were tested. The tested slabs were 3,700 mm long, 1,000 mm wide, and 200 mm thick. They were loaded to failure using a concentrated 87.5 kN load, representing the contact area configuration of a CL-625 truck wheel as prescribed in the current design codes. The study variables included longitudinal reinforcement ratio (1.17% and 0.81%), reinforcement type (BFRP and steel), polypropylene fiber volume (0%, 0.5%, and 0.75%), and fiber combinations [macro polypropylene fibers and a hybrid of macro polypropylene and micro basalt (Ba) fibers]. The test results, including failure modes, cracking behavior, deflection responses, crack widths, along with strain measurements in both concrete and reinforcement, were presented and analyzed. The results revealed that adding fibers to the concrete matrix effectively reduced crack widths and deflections at both service and ultimate load conditions. At service load conditions, the inclusion of polypropylene fibers led to a reduction in crack width by 6.1%–14.3% and in midspan deflection by 6.7%–22.1% compared to the reference slab without fibers. Furthermore, using hybrid reinforcement consisting of macro polypropylene and micro basalt fibers at the same fiber volume (0.75%) resulted in further performance gains, reducing midspan deflection by 11.2% and crack width by 42.8% relative to slabs containing only polypropylene fibers. In contrast, the fibers had a negligible impact on the ultimate load-carrying capacity of the slabs. Conversely, raising the BFRP reinforcement ratio from 0.81% to 1.17% improved the ultimate capacity by nearly 29%. Lastly, the experimental cracking load, deflection, and crack widths were evaluated against current design codes and guidelines.