Towards Safer Roads Post-flooding: Moisture-Induced Pavement Behaviour and Recovery Times

Road infrastructure in Australia is susceptible to aggressive damage caused by excessive rainfall and floods, particularly affecting unbound granular pavements. Annual expenditures by road agencies for rehabilitating damaged roads amount to billions of dollars. Research indicates that maintaining the compaction state of granular materials, specifically Moisture Content and Dry Density, within the dry side of the Line of Optimum (LOO) is crucial for minimizing pavement damage caused by traffic and moisture changes. However, intense rainfall and flooding events can push saturation levels beyond this optimum range. Hence, understanding the moisture variation during and after flood events is of utmost significance. Real-time pavement moisture monitoring employing sensors presents itself as one of the most effective methods to assess moisture variations in pavements during and after flood events. In this study, a road section featuring unbound granular pavement prone to frequent flooding was selected for the installation of moisture sensors to facilitate monitoring. A total of nine sensors were installed, with three sensors per pavement layer, including the base, subbase, and subgrade. Hourly moisture readings were recorded. This paper discusses the moisture variations observed following a flood event, emphasizing the need for a comprehensive evaluation of moisture changes in the post-flood stage to inform pavement management and rehabilitation strategies.