Flexural behavior of a hybrid FRP and lightweight concrete sandwich bridge deck

This paper presents a new concept for a lightweight hybrid-FRP bridge deck. The sandwich construction consists of three layers: a fiber-reinforced polymer composite (FRP) sheet with T-upstands for the tensile skin, lightweight concrete (LC) for the core and a thin layer of ultra high performance reinforced concrete (UHPFRC) as a compression skin. Mechanical tests on eight hybrid beams were performed with two types of LC and two types of FRP/LC interface: unbonded (only mechanical interlocking of LC between T-upstands) and bonded with an epoxy adhesive. The ultimate loads of the beams increased by 104% on average due to bonding. However, the beam failure mode changed from ductile to brittle. The beams using a LC of 44% higher density exhibited an 81% increase in the ultimate load. The manufacturing of the beams proved to be economic in that epoxy and concrete layers were rapidly and easily applied wet-in-wet without intermediate curing times. The experimental results showed positive results regarding the feasibility of the suggested hybrid bridge deck.