Experimental Simulation of Icing-Delay Capability of Asphalt Pavements Made with Wood Sawdust as an Environmentally Friendly Solution

Snow and ice accumulation on asphalt pavements constitute a critical risk to traffic safety, particularly on bridge decks and elevated structures that are highly susceptible to rapid heat loss and premature icing. This study investigated the feasibility of utilizing raw wood sawdust as a partial mineral aggregate replacement in hot-mix asphalt (HMA) to enhance thermal insulation and delay surface icing through a material-based, environmentally sustainable approach. Marshall mixtures incorporating 5%, 10%, and 20% sawdust at different aggregate size scales were produced and mechanically evaluated to determine the optimum replacement configuration. Based on stability-flow performance and volumetric criteria, filler-scale replacement emerged as the most structurally compatible configuration. Icing delay performance was examined through infrared thermographic analysis and controlled freezing simulations, designed to replicate stepwise cooling conditions on steel bridge-deck thermal behavior. Microstructural and morphological characteristics were assessed using computerized tomography (CT) imaging with image-based segmentation and scanning electron microscopy (SEM), and transient thermal analysis (TTA) was employed to quantify effective thermal conductivity. Durability and environmental resistance were evaluated through water sensitivity testing and magnesium sulfate ( MgSO 4 ) cyclic exposure to assess hydrothermal and weathering susceptibility. The results demonstrate that mixtures incorporating 20% filler-sized sawdust maintain adequate mechanical performance while exhibiting enhanced thermal insulation capacity and a remarkable delay in surface freezing relative to the control mixture. Microstructural analyses confirmed homogeneous distribution, effective binder–sawdust interaction, and increased isolated microporosity without disruption of the primary load bearing skeleton. Although bulk thermal conductivity reductions were modest, the combined effects of microstructural modification and transient heat-transfer behavior produced a statistically significant icing-delay response. Overall, the findings indicate that raw wood sawdust can function as a multifunctional ecomaterial, simultaneously contributing to waste and by-product valorization, thermal performance enhancement, and passive anti-icing capability. This study proposes a novel, low-cost, and environmentally responsible material strategy for improving winter road safety, particularly for bridge decks and other icing-prone pavement infrastructures.