Using Cross-Linked Polyethylene Waste in the Production of Concrete: A Durability Assessment

This paper investigates the durability of concrete with stone aggregates partially replaced with hard-to-recycle cross-linked polyethylene (XLPE) waste derived from used electric cables. Specifically, the effects of XLPE content and water-to-cement (W/C) ratio on the water absorption, volume of permeable voids (VPV), permeability, and freeze–thaw resistance of concrete were investigated. Twelve concrete mixes were considered by varying the XLPE content and the W/C ratio. The water absorption and VPV of the concrete specimens were assessed in accordance with ASTM guidelines, and the permeability of the concrete specimens was evaluated by subjecting them to a water pressure of 500 kPa for 72 h and then splitting them in half to measure the (maximum) penetration depth of water. The results indicate that incorporating more XLPE leads to an increase in the water absorption, VPV, and permeability (water penetration depth) of concrete. This is mainly due to the weaker bonding between the XLPE and the binder than that between the stone aggregate and the binder and thus a more porous structure of the concrete at a higher XLPE content. Rapid freeze–thaw test was also conducted following ASTM guidelines to study the freeze–thaw resistance of the concrete by monitoring the surface scaling, mass loss, relative dynamic modulus of elasticity (RDME), and ultrasound pulse velocity (UPV) at intervals of 12 freeze–thaw cycles. It was found that the freeze–thaw resistance of the concrete decreases with the incorporation of more XLPE. This is due to the differential expansion and contraction between the XLPE and the surrounding materials and the higher porosity and thus larger water absorption and more ice formation at a higher XLPE content, leading to higher stresses and more damage to the concrete during the freeze–thaw cycles. However, the results also show that the decrease in the freeze–thaw resistance is insignificant, even with 15 vol.% XLPE incorporated in the concrete, further showing the potential of using XLPE waste in the production of concrete.