Assessing Flooding Effect on Flexible Pavement Serviceability Using AASHTO 1993 Method and FWD Testing: Case Study in Florida

This study aims to evaluate the effect of flooding on flexible pavement serviceability utilizing the American Association of State Highway and Transportation Officials 1993 design method and falling weight deflectometer (FWD) testing based on a case study in Florida. The modulus of pavement layers was back-calculated from FWD deflections and used to calculate the changes in pavement serviceability (ΔPSI) because of flooding. The results showed that the post-flooding pavement conditions can be categorized into three distinct periods. The first period represents an initial weakening phase in which the base, subgrade, and asphalt layers were all compromised, with the ΔPSI increasing by nearly six times. The second period corresponds to a partial recovery phase, during which the base layer recovered, while the subgrade and asphalt layers remained weakened. Therefore, the ΔPSI increase was reduced to 2.8 times, underscoring the critical role of base recovery. The third period is the post-recovery phase, during which both the base and subgrade layers fully recovered, but the asphalt layer continued to have permanent surface damage, with its modulus reduced by an average of 40%. During this phase, the ΔPSI increased by 2.6 times, exceeding the magnitude observed during the moisture recovery period, highlighting the long-term flooding effect. To mitigate flooding-induced pavement deterioration, traffic control can be an effective strategy to maintain acceptable ΔPSI levels in the short-term, while rehabilitation might be necessary to ensure long-term pavement performance. The proposed method provides a practical and efficient approach for quantifying flooding-induced pavement damage and informing transportation agencies of roadway resilience considerations.