Characterization and Modeling of Axial Slab-Support Restraint

Slab-support interaction has long been established as an important consideration in the design and construction of concrete pavements for streets, highways, and airfields. With the current interest in design features such as open-graded permeable bases, unbonded concrete overlays, and whitetopping pavements, the need for an accurate and standard means for characterizing this behavior is evident. With respect to conventional concrete pavements, previous studies have concluded that excessive restraint between the slab and the support layers of a pavement structure can lead to pavement distresses that are ultimately detrimental to the per formance of the pavement. These studies have indicated that undesirable restraint characteristics typically are caused by improper subbase design or construction. The consequences of underestimating or neglecting the support restraint characteristics have been shown to result in uncontrolled slab cracking, excessive joint movements, and underdesigned reinforcement. However, in some cases a high degree of slab-support restraint is desired, such as for whitetopping pavements, especially ultrathin white-topping. Recent developments in characterizing and modeling axial slab-support restraint characteristics of concrete pavements are presented. Test procedures that have been developed to accurately assess the level of axial slab-support restraint present are identified, as are future enhancements to characterization and modeling of this phenomenon.