Response of hybrid concrete incorporating eco-friendly waste PET fiber: Experimental and analytical investigations

High Strength Concrete (HSC) has the ability to strengthen deteriorated concrete members. The performance of HSC incorporating waste polyethylene terephthalate (PET) fibers as a repair material for concrete structures has not been examined extensively in current literature. Thus, more investigations are considered essential in this direction. This endeavor is devoted to examining the flexural behavior of hybrid reinforced concrete beams (HRCB) made with normal concrete (NC) repaired by or bonded to HSC containing waste PET fibers (FRC). The workability and mechanical properties of fresh and hardened FRC were investigated. Moreover, the efficiency of HSC overlay as a repair material for NC substrate was evaluated through a slant shear test (SST) which considered four modes of roughening of the NC interfacial surface. A third-point load test was used to evaluate the structural behavior of the HRCB. The results of the slant shear and flexural tests indicated that the highest bond strength among all of the members was achieved by employing sandblasted and grooved interfacial surfaces between NC and HSC. The flexural capacity for the beams was also predicted via modification of the ACI 318-19 and Jarquio's models, using regression analysis of present experimental records. Good matching was observed between the predicted and experimental ultimate load of the hybrid beams. Finally, the testing observations are noteworthy in the direction of using FRC as a repair material.