Interfacial Enhancement of Polyethylene Fiber-Reinforced ECC via Multi-Walled Carbon Nanotubes Functionalization

Polyethylene (PE) fibers are promising reinforcements for engineered cementitious composites (ECC); however, their highly hydrophobic nature and inherent chemical inertness limit their reinforcing effectiveness. This study investigated the use of different types of multi-walled carbon nanotubes (MWCNTs) to modify PE fibers under varying immersion times. Microstructural characterizations were conducted to investigate the effects of MWCNTs type and immersion time on the surface properties of PE fibers, while mechanical testing was undertaken to evaluate the mechanical performance of the resulting fiber-reinforced cementitious composites. MWCNTs were found to form a uniform coating on the surface of the reinforced PE fibers, resulting in a reduction in water contact angle from 164.2° to 118.4° and an increase in oxygen contents by 242.27%. With increasing immersion time, the single-fiber pull-out strength improved by up to 40.48%, with an optimal modification duration of 8 h. The MWCNTs modified PE fibers were found to increase the 28-day uniaxial tensile strength and three-point bending strength of the cementitious composites by up to 16.17% and 6.96%, respectively, while exhibiting negligible effects on compressive strength. This study implies that MWCNTs can effectively enhance surface wettability and mitigate surface inertness of PE fibers, thereby enhancing the overall performance of ECC.