CRCP: Improved Transition Designs (FHWA-HIF-13-026)
A transition between a continuously reinforced concrete (CRC) pavement and any other type of pavement or structure needs to accommodate a gradual change in either the configuration or the structural capacity of the pavement cross section to maintain rideability, minimize or facilitate slab end movements, and minimize the potential for drainage-related issues to be a factor in performance. In CRC pavements, transitions are design measures to accommodate a uniform or gradual change in slab thickness, width, restraint, or movement (either vertically or horizontally) at a specific location with the intent of preventing early deterioration and minimizing the need for maintenance over the design life.
The junction between a CRC pavement and any other type of pavement such as jointed concrete (JC) or asphalt concrete (AC) pavement or a bridge structure (figure 1) all require a reconfiguration of the pavement typical section to provide an acceptable transition (particularly in light of the magnitude of movements that potentially can take place). A variety of joint configurations and movements can be included in transitions, but those such as jointing details, tie bars, and dowels, along with other details of each transition type, are discussed in this document, which addresses the important factors that must be considered for transition design.
The objective of a transition involving segments of CRC pavement is to maintain uniformity of both support and cracking across the transition segment. Performance-wise, one function of reinforcing steel in CRC pavement is to maintain the stiffness and tightness of transverse cracks, as well as, for instance, transverse header joints (as one type of transition). The capability of maintaining the necessary aggregate the basis for a wide variety of joints when associated with combinations of modifiers that define them with respect to specific design features included in the transition. Elaborating further, deformed bars tie the transition components together and provide load transfer, while smooth dowels transfer load without restraining the opening of the joint. Thickened edge, wide flange, and sleeper slabs are used in cases where wide-opening joints are expected at such transitions as between CRC and bridge approach slabs, where it is important to ensure a minimum level of load transfer. As an example of how these designations can be used, a header joint with deformed bars only would be designated as “Transverse Type A (DB),” a header joint with dowels would be “Transverse Type B (SD),” and a transverse isolation joint with a wide flange would be “Transverse Type C (WF).”
Authors: Dan Zollinger, Ph.D., P.E., and Youn su Jung, Ph.D.