Experimental evaluation of the effect of recycled cross-linked polyethylene on the performance of grouted macadam mixtures

Abstract

ABSTRACT Grouted Macadam (GM) mixtures – recognized as semi-flexible pavement (SFP) materials – offer strong stability in high temperatures, good durability and high load-bearing capacity. However, these materials are prone to environmental and traffic-induced cracking. Cross-linked polyethylene (XLPE), a common high-voltage cable insulation, faces disposal challenges due to limited recycling technology, often leading to burning or burial of these waste materials. In this study, to enhance GM mixture crack resistance and mitigate the environmental impact of XLPE waste accumulation, XLPE material was used in GM mixtures in two methods. In the first group, 15%, 30%, and 45% of 4.75 to 9.5 mm natural aggregates were replaced in volume, with XLPE pseudo-aggregates of the same size. In the second group, XLPE pseudo-fibers (1.9–2.2 cm in length, 1.5 mm thickness) were incorporated as additives in 0.5, 0.7, and 1 volume percentages. The results of mechanical tests on treated GM mixtures showed that adding recycled XLPE improved durability, with a 24.5% and 29.9% enhancement in samples with the most pseudo-aggregates and pseudo-fibers contents. The fracture strain tolerance (FST) index in low-temperature bending tests also increased by 53.8% and 108.9% in mixtures containing XLPE, highlighting its potential to enhance GM mixture performance in various service conditions.