GROUND-SOURCE BRIDGE DECK DEICING SYSTEMS USING ENERGY FOUNDATIONS

Bridges are an integral part of the highway infrastructure and deterioration of the bridge substructure is a major concern that presents significant economic and engineering challenges. The application of deicing salts and chemicals is the major factor that leads to accelerated deterioration of reinforced concrete bridge decks. Ground-source heating can be used to deice bridge decks during the winter and help reduce the use of salts and chemicals. The constant temperature and thermal storage capacity of the ground can be utilized to create a renewable heat source, which can be exploited to heat bridge decks in the winter. In this concept, the foundation system of the bridge substructure and the approach embankment are designed to access this renewable energy source. Heat energy can be collected in the summer through circulation tubes embedded in the asphalt pavement and/or concrete bridge deck. The collected heat energy is injected into the ground through the geothermal loop system, which can be either integrated into the deep foundation elements or embedded in the approach embankment or shallow trenches. During the winter, stored heat energy is extracted from the ground and can be circulated as warm fluid through the tubing system within the bridge deck slab to prevent icing and freezing of the bridge deck. This technology can potentially eliminate and/or drastically reduce the need for chemical deicing agents. Similarly, it can be used to regulate the bridge deck temperature and reduce the intensity of straining due to the sometimes severe heating/cooling cycles between day and night in the summer. This study focuses on concept of ground-source bridge deck deicing with a specific focus on the thermal processes involved in the extraction of heat energy from the ground and heating the bridge deck in the winter. It also presents the results of a model-scale testing program performed using a 2.4-m x 3-m reinforced concrete slab connected to thermal piles. Numerical analyses were conducted to simulate the heating of the bridge deck slab through the circulation tubes. Recommendations are provided for designing ground-source bridge deck deicing systems at a range of environmental conditions.