Geotechnical Investigation of Urban Roads with Composite Pavement Structures Using Destructive and Non-destructive Testing

Effective assessment of bearing capacity of the existing pavement structure as well as proper characterization of materials used in the construction of pavement layers provides critical inputs for rehabilitation design of urban roads. This study presents the findings from a comprehensive pavement geotechnical investigation that was performed on approximately 2300 ft of composite pavement (AC on top of PCC) located on Curtis road in Savoy, Illinois. Non-destructive testing program included falling weight deflectometer (FWD) as well as ground penetrating radar (GPR) at both center and transverse joint locations. Additionally, destructive testing program including pavement borings, pavement coring at crack locations, deep and shallow soil borings, dynamic cone penetration (DCP) testing on aggregate base, and subgrade as well as soil sampling and laboratory testing was performed. GPR scans obtained at three different antenna's frequencies including 2 GHz, 900 MHz, and 400 MHz were analyzed and calibrated by pavement cores to generate pavement layer thickness profiles. Statistical analysis methods were used to identify trends and develop correlations between the laboratory and field test results. This includes finding linkage between the pavement thicknesses obtained through coring and what was estimated using GPR. The findings from this study showed that strength, bonding status, and thickness variability of pavement layers as well as groundwater table and in-situ moisture condition of the subgrade soil significantly affect the surface pavement deflections.