Location and timing of fatigue cracks on jointed plain concrete pavements

The prediction of fatigue cracking in jointed concrete pavements has traditionally focused on transverse cracking initiating from the bottom of the slab and propagating both up and across the slab width. However, field surveys of several locations, particularly in the Western United States indicate that alternative fatigue cracking mechanisms, such as top-down and bottom-up longitudinal cracking, top-down transverse cracking, and corner cracking, exist in substantial quantity. To better understand these alternative cracking mechanisms and to account for such mechanisms in both the analysis and design of jointed concrete pavements, a mechanistic analysis software program named RadiCAL was developed. Mechanistic parameters such as built-in and cyclical curling, axle spacing effects, load transfer, etc. was utilized to predict the critical fatigue crack location using the method of linear fatigue damage accumulation. Several sites in California that have exhibited both traditional and alternative fatigue cracking mechanisms were examined using RadiCAL to validate the proposed mechanistic analysis principles for stress and fatigue damage development.