Evaluating Potential for Reflection Cracking with Rolling Dynamic Deflectometer

A common rehabilitation strategy used for repairing aged concrete pavement is to place a hot-mix asphalt (HMA) overlay on the existing concrete pavement. However, reflection cracks are often found to propagate from the underlying cracks and joints through the HMA layer. As such, much reflection cracking is believed to be caused by differential vertical and horizontal movements in the concrete pavement. A common method of determining the differential vertical movements is by measuring the load transfer efficiency (LTE) at the joints by using nondestructive deflection testing devices. A study was conducted with a rolling dynamic deflectometer (RDD) to evaluate the movement of joints in concrete pavements. Evaluation of joint movements by RDD testing permits estimation of the LTE of each joint or transverse crack. On the basis of the assumption that reflection cracks are more likely to form at joints or cracks with low LTE than with high LTE, pavement engineers can use the results to identify areas with low LTE and perform necessary repairs at these locations to reduce the potential for creating reflection cracking. Field data collected before rehabilitation work on US-82 near Gainesville, Texas, are presented as a case study, and the benefits of continuous deflection profiling for use in the district’s rehabilitation strategy are discussed.