Design and Field Demonstration of ECC Link Slabs for Jointless Bridge Decks

The poor durability of concrete bridges throughout the US is an increasingly large concern for highway transportation authorities. With decreasing budget allocations for infrastructure maintenance, rehabilitation, and replacement, the need for greater durability is apparent. A main source of this poor durability is leaking mechanical expansion joints between adjacent simple spans of multi-span bridges. These joints typically require a large number of expensive maintenance or replacement projects over the service life of the bridge. Using micromechanically designed ECC (Engineered Cementitious Composite) with a tensile ductility four hundred times that of normal concrete, expansion joints can be replaced by ECC link slabs, forming a jointless multi-span bridge. Utilizing the large tensile strain capacity and inherently tight microcracking properties of ECC, these link slabs maintain the simple span performance of the bridge while accommodating mechanical and environmental (i.e thermal) loads typically accounted for by the expansion joints. ECC link slabs allow for a joint free bridge deck, eliminating leaking problems which lead to low durability while creating a smoother riding surface. Design procedures and experimental testing of link slabs is reviewed and an ongoing field demonstration in conjunction with the Michigan Department of Transportation is discussed.