Minimizing Reflective Cracking 3 Minimizing Reflective Cracking With Applications of the Rolling Dynamic Deflectometer

Since reflective cracking is related to both the existing pavement condition and the properties of the overlay material, quantitative methods are required to assess both the vertical movements of the cracks (or joints) for the entire project and the reflection cracking resistance of the over-lay material. Since 2000, the rolling dynamic deflectometer (RDD) has been used in Texas to provide 100 percent coverage of existing joint conditions of concrete pavements being consid-ered for asphalt overlays. The RDD assesses the vertical movements of each joint and identifies the weak support areas and locations where the slabs are rocking. The continuous deflection profiles produced are used to locate areas with high potential for reflective cracking due to poor load transfer and high slab movements. The overlay tester (OT) has been developed as a mix design tool to characterize the ability of an asphalt mix to resist reflective cracking. OT results have not yet been integrated with RDD results to predict the exact extent of reflective cracking that will occur. However, OT results are still good for ranking various mixtures in terms of crack performance, and some guidelines based on OT and RDD results have been developed. This paper presents a series of case studies illustrating the relationship between the RDD de