Conception et optimisation de parapets préfabriqués avec trottoir intégré en béton renforcé de fibres pour les ponts

Bridge barriers provide safety for vehicle passengers by containing and redirecting errant vehicles. Most Canadian bridge barriers are cast-in-place concrete barriers. Concrete barriers deliver great resistance while being efficient for keeping vehicles in the roadway than other types of barriers. While structural adequacy is established for the cast-in-place barriers, there are growing durability concerns associated to their construction sequence. Early-age cracks associated to restrained shrinkage, thermal gradients and traffic vibrations are frequently observed, exposing the young concrete matrix and reinforcement to water penetration. This premature degradation is magnified by the severe freeze-thaw cycles and exposition to the high concentration of chlorides found in the de-icing salts spread on bridge surface. Many barriers require unexpected, and costly premature repairs or replacements. Furthermore, on-site installations of formwork and reinforcement, concrete casting and curing period are time-consuming sequences. Precast barriers can adequately address the aforementioned challenges. Extensive research has been carried at Polytechnique Montreal to develop precast High Performance Fiber Reinforced Concretes (HPFRC) barriers. Restraints-free shrinkage, and curing of concrete in a controlled environment eliminates early-age cracking issues, while the shorter delays associated to on-site installation time of precast barriers significantly accelerates bridge construction and reparation. Finally, the higher durability properties exhibited by HPFRC will subsequently enhance the barriers' lifespan.