Top-down cracking (TDC) is a flexible pavement distress caused by a number of factors, including high contactstresses from truck tires, mix design characteristics, (e.g., binder type and aggregate gradation) and poorconstruction quality, (e.g., segregation and compaction methods). This paper presents the findings of a studyseeking to quantify the effect of these factors on TDC. It consists of a laboratory component involving anaccelerated Wheel Tracking device and a modeling component involving a 3-D non-linear viscoelastic finiteelement model. The laboratory component of the study involved 17 asphalt bituminous slabs, constructed tosimulate the variation in material properties observed in the field as part of an earlier forensic TDC study. Theeffect of air voids, bitumen content and type, aggregate gradation and segregation on TDC were studied under 3temperature conditions. Air voids, segregation and binder content were found to have a significant effect onTDC for all the temperatures tested. Modeling the TDC involved laboratory testing to establish the viscoelasticand tensile strength properties of the asphalt mixtures tested. It was found that the rutted surface contributessignificantly to TDC initiation.
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