Polymeric fibers pull-out behavior and microstructure as cementitious composites reinforcement

Bonding strength is an important factor which affects the performance of fiber reinforced cementitious composites. The present work describes the bonding strength between three polymeric fibers (polypropylene (PP), nylon6,6 (N66), and acrylic (AC)) embedded in a cement paste. Also, the pull-out behavior of fibers from cement matrix along with their tensile behavior was studied. The specimens were tested after 7, 14, and 28 curing days with cement to water ratio of 0.5. It was found that although the higher bonding strength to the cement matrix was achieved for AC and PP fibers, the energy absorption capacity of the fibers during composite fracture is obtained for fiber with lower bonding to the cement matrix (N66). Scanning electron micrographs were used to characterize the fiber surface before and after the pull-out tests.