Mechanical Performance of Epoxy Polymer Concrete with Fly Ash and Hybrid Fiber Reinforcement

This study presents an experimental and statistical investigation into tailoring the mechanical properties of epoxy polymer concrete through the synergistic addition of fly ash, Barchip fibers, and Forta fibers. A series of 15 unique mixture compositions were fabricated into cylindrical specimens and subjected to compression testing to determine their peak force and energy absorption. The results demonstrated that the additives have distinct and conflicting effects on performance. The addition of fly ash alone proved most effective for enhancing compressive strength, increasing the peak force by a maximum of 17.5% to 111,393 N. Conversely, fiber reinforcement was the primary driver for toughness, with a combination of fly ash and Forta fibers yielding the highest energy absorption of 704.0 J, a 107.5% improvement over the baseline. The inclusion of fibers fundamentally transformed the failure mode from brittle fragmentation to a cohesive, ductile response. Analysis of Variance (ANOVA) confirmed a significant trade-off between compressive strength and toughness, driven by the competing mechanisms of matrix densification from fly ash and crack-bridging from fibers. This work provides a framework for optimizing polymer concrete for specific engineering applications, identifying distinct compositions for maximizing either compressive strength, energy absorption, or achieving a balanced performance profile.