Development of a Rainfall Simulator to Evaluate Moisture Sensitivity of Static Loading in Airfield Pavements

It is well known that water intrusion in a pavement system weakens the underlying layers and reduces the overall service life. Water intrusion could be the result of typical rainfall events or catastrophic natural disasters such as hurricanes or flooding conditions. While the case study analysis of in-service pavements or robust modeling efforts can provide insight to infrastructure resiliency, these efforts should be validated through scaled experimentation. To that end, a rainfall simulator was developed to apply controlled, repeatable rainfall to a laboratory-scale plate load test setup for the evaluation of model pavements. A model pavement was constructed that consisted of a clay subgrade layer and a high-quality granular layer. A variety of static loads (0.1, 0.3, 1.0, 3, 5, 10, and 13 kip) were applied to a circular plate in a dry condition and after one of two rainfall events that simulated a rainfall intensity of 1 in./h over either a 1 h duration or a 2 h duration. Instrumentation, including earth pressure cells, linear variable displacement transducers, volumetric moisture sensors, and pore water pressure transducers, was monitored during dry and wet loading conditions. The data highlighted the reduction in performance attributed to the loss of layer stiffness from the simulated rainfall event. The rainfall simulator and modifications made to the plate load test apparatus were found to be successful and could be leveraged to understand pavement drainage modifications and stiffness impact under a variety of conditions.