Abaca fiber as an efficient reinforcement for high mechanical performance in metakaolin‐based geopolymers

Abstract This study introduces an innovative method for efficiently integrating abaca fibers into a potassium‐based geopolymer (KGP) material. Geopolymers often suffer from brittleness, and composite designs have been explored as a solution to enhance their strength and ductility. While synthetic reinforcements are commonly employed due to their consistent properties, natural fibers offer a renewable and eco‐friendly alternative. However, their widespread use has been hindered by complex and time‐consuming treatments, resulting in variable morphologies that affect fiber‐matrix adhesion. It is worth noting that previous research has primarily focused on alkali‐activated and cementitious applications, leaving a knowledge gap in understanding its interactions with calcium‐free, metakaolin‐based geopolymers. Consequently, this study aimed to simplify the conversion of raw abaca into uniformly chopped filaments, facilitating their integration into KGPs at levels of up to 7 wt%. The mechanical evaluation revealed exceptional performance, with compressive strengths reaching up to 45 MPa. A thorough analysis confirmed robust, fiber‐matrix adhesion and identified the presence of lignin and cellulose, significantly contributing to the fiber's strength. Flow table tests showcased their versatility, transitioning from high flowability (1 wt%) to complete shape retention (7 wt%). Furthermore, all variations exhibited great ductility, multiple cracking formation, and minimal variability in mechanical properties.