This study investigated the durability performance of fresh and hardened geopolymer mortars with and without synthetic fibers. To examine two separate durability tests, one group of samples was first exposed to acid exposure, and the other group was subjected to freeze-thaw cycles in seawater. Additionally, a third group was left unexposed for comparison. Fiber-containing and fiber-free geopolymer samples were examined for their fresh and hardened properties before and after durability testing. Physical, mechanical, and microstructural analyses were performed for this purpose. The effect of fiber on the geopolymer samples differed before and after durability testing. The highest pre-durability compressive strength was obtained from the geopolymer sample with 1.5% fiber, recording a 21.62% increase compared to the samples without fiber. On the other hand, after acid exposure and freeze-thaw cycles in seawater, the samples with 1.5% fiber had the lowest compressive strengths, with reductions of 24.07% and 11.51%, respectively, compared to the fiber-free samples. Thus, this study emphasizes that the effect of fiber in geopolymer mortar samples may show differences before and after durability exposures.

Keywords: Metakaolin, Macro synthetic fiber, Freeze-thaw, Sulfuric acid.