Pullout Properties of PET and Polypropylene Fibers for Concrete Reinforcement

Abstract

Fiber reinforced concrete (FRC) or mortar (FRM) is one of the future promising composite materials and suits, for example, today's rapid excavation by a tunnel boring machine, a boom header or a continuous miner. It is well known that FRC or FRM is improved in toughness and crack resistance mainly by the pullout resistance of fibers. Though some pullout tests have been published, fundamental data concerning pullout resistance are still insufficient and pullout process of fibers is not clear.
In this study, pullout test was conducted pulling a single PET or polypropylene fiber out of the mortar sample at a constant displacement rate by a servo-controlled testing machine. The maximum pullout resistance of PET / polypropylene fiber was considerably lower than that of steel fiber. The displacement at the peak value was larger than that of steel fiber. The coefficient of variation of the maximum pullout resistance was smaller than that of steel fiber. After the peak pullout resistance, pullout resistance-displacement curve was decreasing linearly with displacement though undulations synchronized with the indent interval were observed.