Nondestructive Evaluation of Rigid Pavements Using Road Rater Deflections

Road Rater deflections have been used to determine in-place structural conditions of rigid and composite pavements, based on modifications of principles and experience with the structural evaluation of flexible pavements. Details of the use of elastic layer theory to simulate deflection measurements associated with loadings for the Kentucky Road Rater are presented. Included is an illustration of the use of field deflection measurements to "back calculate'" in-place moduli. The procedures are generally iterative and involve matching measured deflections with theoretical deflections. Elastic layer principles have been used to simulate deflections only at the midslab position. Relationships regarding deflections at other locations on the slab currently involve empirical analyses. Evaluations involving the effects of pavement temperature, time of day, season, etc. are still empirical. In summary, major aspects of this paper will be twofold. One will be related to procedures and principles applied to the use of deflections and layer elastic theory to estimate effective parameters representative of existing in-place pavement conditions. The second will be related to the application of deflection measurements and evaluation methodologies to determine appropriate recommendations of rehabilitation strategies and scheduling for rigid pavements.