Using Nondestructive Testing Technologies to Assist in Selecting the Optimal Pavement Rehabilitation Strategy

A comprehensive evaluation of pavement condition and an understanding of the underlying causes of pavement distress is vital in selecting the optimal rehabilitation strategy. Three projects were investigated in this study to demonstrate the application of nondestructive testing technologies in this selection process. Ground Penetrating Radar (GPR), Falling Weight Deflectometer (FWD), and Dynamic Cone Penetrometers (DCP) were successfully used on these TxDOT projects. GPR was employed successfully to locate defects in the hot mix surface layer that were responsible for the chronic distress on US 69. This roadway was rehabilitated previously but the strategy used had not addressed the root cause of the pavement problem. FWD and DCP data were also used to determine the structural capacity or layer moduli of the pavement system that allows the designer to derive the overlay thickness. Coring and trenching were utilized to verify the defects detected in the GPR data. The advantage of nondestructive testing is that it provides a comprehensive evaluation of subsurface conditions throughout the entire project, not only at locations where coring and trenching are performed. Furthermore, GPR was employed to verify a rehab design of an old JCP pavement on SH 73. Originally, the plan called for pressure grouting to fill the subsurface voids. However, GPR found no voids under the JCP slab; this was validated in subsequent coring. Therefore the GPR results helped district personnel to eliminate the cost of the pressure grouting. For comparison purposes, GPR results from IH 45 and US 82 (where there were voids under JCP slabs) were utilized.