Assessment of pavement structures using non-invasive imaging and geotechnical testing

The emphasis of this research was to assess the properties of existing road and airport pavement structures in Beirut using geotechnical and geophysical techniques. A total of three sections, consisting of Portland Cement Concrete and Asphalt-Concrete pavement, were tested: two segments of road way approximately 250 m long and, one segment of runway of approximately 250 m. Electrical Resistivity (ER), Multichannel Analysis of Surface Waves (MASW) and Ground Penetrating Radar (GPR) surveys were conducted on the three segments. Geotechnical testing, (i.e. dynamic cone penetration test), was also conducted to assess the subgrade of these pavements. Soil and core samples were collected for laboratory testing. Obtained data, to date, showed three non-invasive techniques (i.e., ER tomography, Vs 1D and 2D soundings, GPR) correlated reasonably well and generated reliable and comprehensive information about the types of soils and pavement conditions. The results showed that ER, MASW and GPR are effective techniques for investigating any anomalies and distress within pavement structures. Geotechnical results and Penetration Index (PI) showed significant correlations with the geo-electric characteristics of pavement materials. ER, shear—wave velocity and penetration index showed also significant correlations among each others. Findings from this study demonstrate the effectivenessof non-invasive imaging (ER tomography, Vs 1D and 2D soundings and GPR) as an alternative to dynamic cone penetration test for assessing pavement structures and an effective approach to improve the accuracy/reliability of imaging/inspecting pavememt conditions.