Investigation of Deterioration of Stainless Steel Dowel Tubes Under Repeated Loading

Project summary:

The Minnesota Department of Transportation (MnDOT) has selected a new dowel bar to be used as a bid alternative for its high performance Portland Cement Concrete (PCC) pavements. This dowel bar is a 316L stainless steel schedule 40 pipe, with a finished (polished) surface, conforming to ASTM A312. In this study, long-term performance of the new dowel bar was investigated by subjecting a doweled joint to accelerated repeated loads through the use of the Minnesota Accelerated Loading Facility (MinneALF-2).

Although this dowel bar should provide sufficient shear transfer capacity and low concrete bearing stresses, there is a concern that lack of a solid core may not provide sufficient resistance of the cross-section to distortion under a heavy axle loading. Assessment of the new dowel bar performance was performed based on comparison with the standard 1.5 inch diameter epoxy -coated round steel dowel.

The following tasks were accomplished: redesign, assembly, and calibration of a new version of Minne-ALF; development of experimental design matrix; conduct of accelerated full-scale testing; and post-testing evaluation. The results from the MinneALF-2 tests illustrated that while the LTE for the stainless steel dowel tubes was lower than the LTE for the epoxy-coated dowels, the stainless steel tubes are capable of providing over 70% LTE in the long-term when installed in concrete pavement joints. The ability to withstand deformation and corrosion while providing sufficient long-term performance suggests that the stainless steel tube dowel is an attractive alternative to the solid epoxy-coated dowel for use in long-life pavements.