Flexural Behavior of Basalt Fiber–Reinforced Concrete Slab Strips with BFRP Bars: Experimental Testing and Numerical Simulation

This study investigated the flexural behavior of a new one-way concrete slab system reinforced longitudinally with basalt fiber–reinforced polymer (BFRP) bars and cast with basalt fiber–reinforced concrete (BFRC). The study included experimental testing and three-dimensional finite-element (FE) modeling of eight slab strips, $500\times 175\times \mathrm{2,500}\mathrm{mm}$ each. The investigated parameters included the volume fraction of the basalt fibers added to the concrete mix (0%, 0.5%, 1%, and 2%) and the BFRP reinforcement ratios (1.4 and 2.8 times the balanced reinforcement ratio). The effect of varying the fiber volume fraction on the mechanical properties of concrete was first assessed. The test results showed that increasing the fiber volume fraction increased the compressive strength and the modulus of rupture of the concrete. Slab strips with higher dosages of fibers showed an increased number of cracks and a considerable enhancement in their cracking and ultimate capacity. A volume fraction of 0.5% of basalt fibers had an insignificant effect on the flexural performance of the specimens, and therefore 1% of basalt fibers were recommended as a minimum dosage. Increasing the fiber volume fraction led to a noticeable increase in the ductility of the slab strips at all stages of loading. The FE models provided reasonable prediction of the nonlinear structural behavior of the slab strips. The Variable Engagement Model, initially developed for steel fiber–reinforced concrete, was assessed to describe the BFRC mixes. Good correlation between the numerical and experimental results in terms of cracking loads, load-carrying capacities, deflections, and crack pattern was obtained.