Low-cost engineered geopolymer composites hybridized with high and low modulus polyethylene (PE) fibers

Engineered geopolymer composite (EGC), which has the advantages of high ductility of engineered cementitious composites (ECC) and low carbon of geopolymers, has received increasing attention. However, the high cost of fibers used to enhance the ductility of EGC hinders its engineering applications. In this study, economical EGCs with hybrid PE fibers were developed to meet this challenge by utilizing low-cost, low-modulus PE fibers (PE40) to partially or fully substitute for the conventional high-cost, high-modulus PE fibers (PE110). Compressive, uniaxial tensile and single fiber pull-out tests were performed on EGCs with different PE40 fiber replacement ratios (0 %, 30 %, 50 %, 70 % and 100 %) to investigate the mechanical properties. Scanning electron microscopy (SEM) was further employed to examine the bridging effect between the fiber and matrix. Additionally, the sustainability and economic potential of EGCs at various PE40 fiber replacement ratios were also evaluated. The results indicate that replacing PE110 fibers with PE40 fibers can enhance the compressive strength of EGCs. Notably, EGCs with PE40 replacement ratios ranging from 30 % to 100 % demonstrated typical strain-hardening behavior. It is noteworthy that the EGC with 100 % replacement ratio of PE40 fibers still retains a high tensile strain capacity of 5.81 %, exhibiting 43 cracks with a well-controlled crack width of approximately 108 μm. The environmental impact of EGC with hybrid fibers is extremely low, and the cost is significantly lower compared to EGCs/ECCs with the same fiber volume fraction. The research findings provide valuable insights for the design and application of the low-cost, high-performance EGC.