Multicriteria Decision Making Guided Optimization of Recycled HDPE Fiber Content for Sustainable Utilization in Concrete

The transformation of plastic waste into structural concrete presents a promising avenue for reducing environmental impacts while enhancing material performance in alignment with global sustainability frameworks. This study examined the integration of recycled high-density polyethylene (rHDPE) fibers sourced from postconsumer plastic ropes into M30 grade concrete as a sustainable reinforcement strategy. Fibers measuring 30 mm in length and 0.4 mm in diameter were incorporated at volume fractions ranging from 0.3% to 0.8% to assess their effects on the fresh, mechanical, and durability properties of the concrete. The optimal compressive strength (50.36 MPa) was achieved at a fiber content of 0.4%, indicating a 12.5% increase over that of the control. The maximum enhancements in the splitting tensile strength, flexural strength, and shear strength were observed at a fiber content in the range of 0.4%–0.7%. Although the workability decreased by 66%, the durability was significantly enhanced as water absorption, sorptivity, and carbonation depth were reduced by 43.9%, 36.6%, and 28.9%, respectively, at a range of 0.7%–0.8% fiber dosage. The impact resistance increased by 59.4%, indicating an improved energy dissipation. A multicriteria decision-making (MCDM) framework was employed to determine the optimal fiber content based on the performance criteria. The utilization of rHDPE fibers fosters a circular economy by repurposing plastic waste into value-added construction materials. This approach supports sustainable development goals (SDG) 12 and 13 by mitigating plastic pollution and advancing ecoefficient concrete technology.