Journal Article

Optimization of Activator Modulus to Improve Mechanical and Interfacial Properties of Polyethylene Fiber-Reinforced Alkali-Activated Composites

Zhu, Yingcan, Yang, Heng, Jia, Mingkui, Guo, Yu, Liu, Dong, Zhang, Junfei

2026

Overview

With the growing demand for sustainable and high-performance construction materials, alkali-activated materials (AAM) have attracted significant interest as eco-friendly al-ternatives to cement-based systems. Nevertheless, the tensile ductility and AAM–concrete interfacial bonding of polyethylene fiber-reinforced AAM remain insufficiently understood, and systematic knowledge on how activator modulus governs these multi-scale properties is still limited. This study aims to clarify how activator modulus (Ms = 0, 0.5, 0.8, 1.1, 1.4) influences the mechanical, interfacial, and microstructural behavior of an engineered AAM reinforced with polyethylene fibers. The effects are investigated through uniaxial tensile tests, single-fiber pull-out experiments, bond tests with concrete, and microstructural analyses (SEM, XRD, CT). Results show that an activator modulus of 1.1 yields the best overall performance, achieving a 28-day tensile strength of 3.77 MPa and ultimate tensile strain of 3.68%, representing increases of 231% and 64.6% compared with a modulus of 0. Microstructural observations confirmed that the optimized modulus promotes extensive gel formation, improves fiber–matrix interfacial bonding, and enhances strain-hardening with multiple microcracks. Interfacial tests further demonstrated that Ms strongly affects bond performance between AAM and concrete, with 1.0–1.1 providing balanced adhesion and matrix ductility, while excessive activation (Ms = 1.4) caused interfacial defects and bond deterioration. These findings deepen the understanding of the micromechanical role of activator modulus and provide guidance for the mix design of durable, high-ductility AAM suitable for sustainable infrastructure.

• Publisher: MDPI AG
• Subject: alkali-activated materials (AAM) / alternative to cement / Bonding / Building materials / By products / Carbon / Caustic soda / Cement / Chemistry / Concrete / Corrosion / Design / Ductility / Fiber composites / Fiber pullout / Fiber reinforced polymers / fiber–matrix interfacial bond / Green buildings / Green infrastructure / Interfacial properties / Investigations / Mechanical properties / Microcracks / Polyethylene / polyethylene fiber reinforcement / Polyethylenes / Raw materials / Sodium / Strain hardening / strain-hardening tensile behavior / sustainable development in building materials / Tensile strain / Tensile strength / Tensile tests