Rapid Inductive Heating of Asphalt Concrete to Hot Mix Temperatures for All-Season Pothole Patching: Feasibility Study

Potholes are a common pavement distress, a nuisance to roadway users, and a maintenance problem for state and local agencies. Patching materials are typically cold mix asphalt (CMA), generic or proprietary, in winter seasons and, ideally, hot mix asphalt (HMA) in warm seasons. Although proprietary CMAs generally perform better than generic CMAs, winter repairs with any CMA are usually considered temporary until semi-permanent repairs can be made. However, re-repairing is cost-ineffective to the point the mantra “do it right the first time” has been adopted by some states and researchers. Induction heating has the potential to rapidly heat standard-size containers (e.g., 19 L) of inductive asphalt mixtures to hot mix temperatures (e.g., 150°C) in a matter of minutes (e.g., 5 min), which would allow patching to be conducted with high-quality materials even in winter when conventional HMA is unavailable. The objective of this paper is to investigate the feasibility of this concept. A laboratory investigation evaluated multiple steel aggregates for inclusion in the inductive HMA (iHMA) and designed an iHMA mix that was field-validated by patching simulated potholes. Containers of iHMA were successfully heated in cold weather (–11 to 0°C) to 160°C in 5 min with 15% steel aggregate by volume. During full-scale trafficking tests, iHMA patches exhibited comparable rutting characteristics to control HMA patches.