Treatments on Polypropylene Macro Synthetic Fibers for Improving Adhesion in Structural Concrete Reinforcement: A Systematic Review

ABSTRACT Concrete is the most used higher compressive strength‐building material, albeit brittle to tensile, and flexural loads. Polypropylene (PP) synthetic polymeric macrofibres are commonly employed as reinforcement material to prevent this situation from occurring because of their low weight, chemical resistance, and enhancing crack control and durability. Nevertheless, the inertness and hydrophobic nature of PP limit the bond between the fibers and the cement matrix, thus leading to inefficient stress transfer via the interfacial transition zone (ITZ). The efficiency of surface treatment approaches enhancing the adhesion between PP fibers and concrete is evaluated. The effect of chemical modification and physical treatment on fiber wettability and resulting ITZ microstructure are analyzed, showing the improvement of mechanical properties (post‐crack energy absorption, flexural toughness, pullout resistance) as a result of concrete performance in which interface ITZ is modified. Issues related to treatment scale‐up, sustainability of process and long‐term durability in aggressive environments are also addressed. Directions for future research are finally suggested as chemical–physical hybrid treatments, aging acceleration processes, and computational models for stress transfer and optimum treatment parameters as a function of microstructure. Processing methods are integrated with microstructure development and evolution and mechanical response in this review, providing a roadmap for designing next‐generation fiber‐reinforced concretes with enhanced performance and durability.