Evaluation of temperature dependency of falling weight deflectometer measurements for asphalt mixes with waste low-density polyethylene

Overlay design for flexible pavements requires normalisation of surface deflections and back-calculated modulus values obtained from falling weight deflectometer (FWD) testing to a reference temperature using appropriate correction models. Existing temperature correction models are primarily calibrated for conventional asphalt mixtures without additives and reference temperatures between 20 °C and 35 °C, limiting their applicability in tropical climates. In recent years, the incorporation of waste low-density polyethylene (wLDPE) in asphalt mixtures has emerged as a sustainable solution for plastic waste management. This study investigated the temperature susceptibility of flexible pavement sections constructed with bituminous concrete (BC) wearing courses containing varying wLDPE dosages (0%, 4%, 6% and 8%) using the dry mixing process. FWD evaluations were performed at pavement temperatures ranging from 30 °C to 50 °C. The results indicate that wLDPE-modified mixes exhibit significantly lower temperature susceptibility compared to conventional mixes. Based on in-situ deflection data and mix characteristics such as air voids, layer thickness, binder content and wLDPE dosage, upgraded temperature correction models were developed to normalise FWD measurements to reference temperatures within the tropical range of 20 °C–50 °C. Statistical analysis confirmed that the proposed models more accurately capture the reduced temperature sensitivity of wLDPE-modified mixes. These models provide a practical framework for improving overlay design reliability for asphalt layers incorporating wLDPE under high-temperature conditions.