Flexural Performance of Sustainable Engineered Cementitious Composites with Recycled Polyethylene Terephthalate Fibers

Strain-hardening/engineered cementitious composites (SHCC/ECC) are fiber-reinforced concrete with outstanding tensile performance, but its widespread application is constrained by the high initial material cost primarily comes from high-performance polymer fibers like polyvinyl alcohol (PVA). This study explores partial replacement of PVA fibers with recycled polyethylene terephthalate (PET) fibers (with and without surface treatment) to reduce the cost and environmental impacts of ECC without compromising its flexural performance. Nine ECC mixes with a constant total fiber content of 2.0 vol% were tested under four-point bending. With 50% PET replacement, ultimate tensile strain decreased from 4.63% (control) to 1.83%–2.16%, whereas flexural strength only decreased from 11.40 MPa (control) to 10.10–10.19 MPa, and curvature capacity remained 79%–82% of the control. At 100% PET replacement, surface treatment improved the flexural ductility by about 70%. Finite element analysis confirmed the test results in terms of both flexural strength and deformation with good alignments. Additionally, overall performance evaluation of the developed ECC was assessed through a five-dimensional mechanical performance assessment framework and breakdown analysis of embodied energy, CO 2 emission, and material cost. The results support the hybrid PVA/PET fiber system as a feasible means of creating sustainable ECC for structural applications.