Experimental Study on Concrete with Recycled PET Fibers for Structural Application

This study investigates the mechanical behavior of concrete reinforced with recycled polyethylene terephthalate (PET) fibers at volume fractions of 0.2% and 0.4%, aiming to assess their potential for enhancing structural performance and sustainability. Although the compressive strength showed a slight reduction, 9.7% for 0.2% recycled PET content and 38.57% for 0.4%, the flexural performance improved significantly. The first-peak flexural strength increased from 5.21 MPa (control) to 5.58 MPa with 0.2% recycled PET fibers. Most notably, the residual flexural strength at a deflection of L/600 rose from 0.62 MPa in the control to 1.82 MPa for the 0.4% fiber mix, an enhancement of nearly 200%. Crack mouth opening displacement (CMOD) analysis confirmed this trend, showing that the fiber-reinforced concrete maintained over 0.20 MPa of residual strength at 3.5 mm crack width, whereas the control failed before 2.5 mm. These results demonstrate that incorporating recycled PET fibers not only improves ductility and postcracking behavior but also contributes to better crack control and energy absorption. This enhancement in flexural toughness, combined with the environmental benefit of reusing plastic waste, supports the application of PET fibers as a promising, sustainable alternative for improving the ductility and serviceability of concrete structures.