Impacts of Birds Droppings and Deicing Salts on Highway Structures: Monitoring, Diagnosis and Prevention

Transportation structures are crucial to the sustainable development of economy and life supporting facilities. Yet, it is estimated that approximately $46.8 billion dollars are spent on the maintenance, prevention and improvement of current transportation systems through 2009, due to the deterioration of highway infrastructures (SAFETEA-LU 2005, FHWA 2005). The common mechanisms for the deterioration of transportation structures include corrosion, sulfate attack, alkali-aggregate reaction, freeze-thaw cycling, creep and shrinkage, and temperature related effects. Corrosion caused by various salts, e.g., bird droppings and deicing, has contributed greatly to the deterioration of transportation structures and brought huge economic and societal loses. Salts can diffuse into the construction materials and thus lead to corrosion, concrete cracking and structures damages. Bird droppings are extremely acidic and contain high concentration of various salts that can significantly penetrate the concrete or steel structure. It is suspected that several bridge damages, including the 2007 Minnesota bridge collapse, were related partially to bird dropping corrosion. It is agreed that the high acidic nature of bird droppings can accelerate the corrosion process of highway structures. Deicing salts that the Delaware Department of Transportation (DelDOT) used on transportation structures during cold-weather periods to promote highway safety, is another major contributing source to the corrosion of transportation structures. Once the run-off from the birds droppings and deicing salts migrate to the surrounding environment, it can post long-term corrosion potential to existing transportation structures and drainage systems. The proposed project will develop decision-making criteria and tools useful to DelDOT in monitoring, diagnosis and corrosion prevention brought by bird droppings and deicing salts. The information to be established in this proposed research will be valuable to life cycle cost modeling of transportation structures.