Influence of 3D-printed fiber geometry and content on the mechanical and fracture behavior of cemented sand

This study assessed the influence of geometry and dosage of 3D-printed PLA + fibers on the mechanical and fracture behavior of cemented sand stabilized with silica fume. Four fiber geometries—straight (S), enlarged-end (E), indented (I), and hooked-end (H)—were manufactured via Fused Deposition Modeling (FDM) and incorporated into sand specimens stabilized with 7% Portland cement and 0.5% silica fume (by dry weight). After 42 days of curing, compressive strength, tensile strength, and flexural strength tests were conducted according to ASTM standards. The addition of 5% silica fume enhanced compressive strength by 15%, contributing to improved particle bonding and matrix cohesion. Moreover, the incorporation of 3D-printed fibers enhanced mechanical performance, with gains of up to 30% in compressive strength, 18% in tensile strength, and 25% in flexural strength compared to unreinforced specimens. The stiffness increased significantly with silica fume (E₅₀ = 285.7 MPa) and with indented 3D-printed fibers at 0.6% content (E₅₀ = 236.8 MPa), indicating the contribution of silica fume in refining the soil matrix and enhancing particle bonding through pozzolanic activity. Specimens with enlarged-end fibers (E) exhibited the best overall performance. The energy absorption capacity (EAC) increased by 45%, with values rising from 128.1 MJ/m3 to 209.6 MJ/m3 for specimens containing 0.6% fiber, indicating enhanced toughness and crack resistance. Failure mode analysis revealed a transition from brittle to more ductile and progressive behavior in fiber-reinforced composites. Statistical analyses confirmed the significance of these improvements. Overall, the study highlights the promising role of 3D-printed fibers combined with silica fume as a sustainable and effective reinforcement strategy for improving the strength, ductility, and durability of cemented soils in geotechnical and civil construction applications. © 2025 Elsevier B.V., All rights reserved.