Laboratory Investigation of Concretes for Partial-Depth Link Slabs

About the report:

Bridge deck joints frequently leak, leading to the infiltration of harmful chlorides and other solutions that accelerate the deterioration of beam ends, bearings, and substructures. To mitigate this costly maintenance issue and extend the service life of conventional bridges, the Virginia Department of Transportation has been using full-depth link slabs to eliminate existing deck joints. However, these full-depth link slabs are time consuming to build and cause traffic interruptions. A possible alternate solution is the partial-depth link slab. This option presents advantages, including the elimination of bottom of deck formwork, leading to shorter construction durations. In addition, this option reduces the quantity of materials used because of the reduced thickness of the slab.

In this study, concrete mixtures, including fibers that exhibit ductility for crack control and high tensile strength for short splice lengths, were investigated to use in partial-depth link slabs. To ensure timely opening to traffic, concretes with high early strength were included. The project led to the development of two categories of fiber-reinforced concretes—one with conventional compressive strengths and the other with compressive and tensile strengths exceeding 10,000 psi and 1,400 psi, respectively. Both designs were high-performance concretes with low permeability and high ductility. Varying levels of residual strengths were present, with all the high‑strength specimens exhibiting deflection hardening. The proper strength level and fiber type and amount can be selected, depending on the needs, to control cracking and provide satisfactory splice lengths for the reinforcement in partial-depth link slabs.

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