Micromechanical design based on microscale fiber/matrix interactions for single PE fiber pullout

A modified model is established for hydrophobic polyethylene (PE) fibers during the pullout process in the ultra-high-strength and high-ductility cementitious composites (UHS-HDCCs). Single fiber pullout tests with different embedded lengths and embedded inclination angles were tested to determine the fiber/matrix interaction characteristics. All curves of the single fiber pullout exhibited slight pseudo-strain hardening behavior. Based on these fiber pullout curves, slip hardening strengthening coefficient μ= 0.62 and inclination hardening factor ω= 35 N/(m·rad) were proposed to capture a new mechanism of single PE fiber pullout from a dense matrix, and to modify the single fiber pullout mathematical model in the classical high-ductility cementitious composites (HDCCs). The potential fiber debonding and the slip rupture was considered to achieve explicit expressions of the design derivation process based on the principle of micromechanics and fracture mechanics. The results of the single fiber pullout test verify the feasibility of the proposed theoretical model. This work illustrates a better understanding of PE fibers being pulled out of a high-density matrix and provides a foundation for a more accurate evaluation of bridging stress versus crack opening width at the macro level.