Influence of Fiber Reinforcement on the Mechanical Properties and Durability of 3D Printed Concrete

Introduction: Three-dimensional concrete printing (3DCP) has emerged as a transformative construction technology capable of reducing material wastage, labor requirements, and construction time while enabling complex architectural designs. However, the layer-by-layer deposition process introduces anisotropy, weak interlayer bonding, and brittle failure, which limit the structural performance and long-term durability of printed elements. Fiber reinforcement has been proposed as an effective material modification strategy to overcome these challenges by enhancing crack resistance, ductility, and mechanical performance.

Methodology: The investigated materials, basalt, polypropylene (PP), glass, carbon, polyvinyl alcohol (PVA), polyethylene (PE), and hybrid fiber systems, were systematically analyzed. The comparison focused on fresh-state printability, compressive strength, flexural strength, tensile behavior, interlayer bonding, toughness, and durability-related parameters, including crack resistance and long-term structural stability. Quantitative performance values reported in experimental investigations were compiled to identify optimum fiber types and dosages.

Results and Discussion: The study demonstrates that reinforcement materials significantly improve both mechanical and durability performance when incorporated at optimized dosages. Steel fibers exhibited the highest mechanical enhancement: approximately 0.7% fiber content increased compressive strength by 22.5% and flexural strength by 71.1%, while 2% steel fibers produced excellent deflection-hardening behavior. Basalt fibers showed optimum performance at 0.3–0.5%, improving compressive strength by 28%, interlayer shear strength by 61%, and flexural strength by 21%. Polypropylene fibers at 0.2% enhanced buildability, crack resistance, and interlayer bonding, whereas 0.75–1.0 vol% PP fibers significantly increased fracture energy and ductility. Glass fibers improved flexural strength by 75–82%, although compressive strength decreased by 22–35% at higher dosages because of increased porosity. Advanced reinforcement systems, including carbon, PE, and PVA fibers, achieved compressive strengths approaching 80 MPa, flexural strengths of approximately 30 MPa, tensile strengths of 5.7 MPa, and tensile strain capacities of 11.4%, demonstrating exceptional toughness and crack resistance.

Conclusion: Fiber reinforcement substantially enhances the structural reliability and durability of 3D printed concrete; however, its effectiveness depends on the appropriate selection of fiber type and optimized dosage. Steel fibers provide the greatest strength enhancement, basalt fibers improve interlayer performance, polypropylene fibers maximize durability and printability, while glass and hybrid fibers significantly improve flexural and tensile behavior. The findings indicate that optimized low-to-moderate fiber contents provide the best balance between printability, mechanical performance, and long-term durability.