Flexural behaviour of concrete slabs reinforced with thermoplastic FRP grids: A design-oriented experimental evaluation

Fibre-reinforced polymer (FRP) reinforcement offers corrosion resistance and a high strength-to-weight ratio, making it attractive for concrete elements exposed to aggressive environments. This paper investigates the flexural behaviour of concrete slabs reinforced with thermoplastic FRP (TP-FRP) grids and evaluates the implications for design checks in current FRP provisions. Eight one-way slabs were tested under four-point bending with variations in grid layer count and transverse cross-tape configuration. Increasing reinforcement ratio improved stiffness retention after cracking, load-carrying capacity, and crack control. Cracking moments were generally over-predicted by CSA S806–12 and ACI 440.1R−15, while ultimate moments were predicted with average experimental-to-predicted ratios of approximately 0.95. Among several effective moment-of-inertia formulations, a tri-linear moment–curvature approach provided the best overall deflection prediction. A field application at a precast facility confirmed the placement feasibility and constructability of TP-FRP grids at full scale. Overall, FRP rupture or serviceability limits governed capacity across the tested range, supporting design-oriented use of existing FRP checks for TP-FRP grid-reinforced slabs, with noted caveats for deflection prediction at very low reinforcement ratios.