Geophysical and Geotechnical Investigation of Pavement Structures and Bridge Foundations

Research Article

Austin J Earth Sci. 2014;1(1): 6.

Geophysical and Geotechnical Investigation of Pavement Structures and Bridge Foundations

Reda Amer1*, Ahmed Saad2, Tharwat Abd Elhafeez2, Hassan El Kady2 and Mohamed Madi3

1Department of Earth & Environmental Sciences, Tulane University, USA

2Department of Geology, Al Azhar University, Egypt

3Orascom Construction Industries, Egypt

*Corresponding author: :Reda Amer, Department of Earth & Environmental Sciences, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118, USA

Received: April 27, 2014; Accepted: May 12, 2014; Published: May 14, 2014


This paper presents the results of the integration of conventional investigation methods (visual condition survey, boreholes, asphalt coring, and Standard Penetration Test) with Ground Penetrating Radar (GPR) to generate detailed pavement condition information for a section of the Cairo-Alexandria desert highway and evaluation of the Janaklis bridge deck. Comparison and correlation of the different data types demonstrated that the effectiveness of the GPR as a supplementary tool to conventional pavement condition investigations in identifying anomalies in the buried pavement structure and bridge deck. GPR results indicated that the block cracking of the highway section is related to the presence of moisture and/or clay in the subgrade soils which induces stress in the hot mix asphalt (HMA) layer due to elasticity and volume change between wet and dry states. GPR image shows deterioration in the middle of the Janaklise bridge deck which could be due to changes in concrete material properties associated with the delamination process, or to moisture infiltration into the delaminated area from the water canal. Low strain Pile Integrity Testing (PIT) was performed using Pile Echo Tester (PET) and indicated that there are no detected defects of the Janaklis bridge piles. GPR and PET provide a time and cost-effective means of obtaining high resolution data required for the design and rehabilitation of airport runways, highways, and bridges.

Keywords: Geotechnical; Ground penetrating radar (GPR); Pavement structures; Bridge deck; Bridge foundations


The most common flexible pavement distresses are cracking, roughness, weathering, raveling, rutting and bleeding. Pavement maintenance is required to improve the quality of the pavement surface, extend pavement life and enhance pavement performance in a costeffective and efficient way. If the distresses identified in a pavement are related to structural deficiencies, the pavement section is most likely not a candidate for preventive maintenance treatment, and should be scheduled for rehabilitation or reconstruction. Conventional methods of pavement failure investigation include visual observation of base course condition, extraction and examination of core samples from rutted sections and analyzing lab test results from the cores. These methods are expensive and required a lot of work and time to be performed. Geophysical and geotechnical methods have been lately used as nondestructive, time and cost-effective tools to provide information about the pavement structures [1-4]. Ground penetrating radar (GPR) has been used for pavement layer thickness evaluation, bridge deck condition assessment, measurement of depth of rebar, and dowel location [5-9]. The results of these studies show that GPR can be a useful tool for estimating total repair quantities and general areas of deterioration, but less capable of pinpointing specific repair locations. The accuracy of GPR results depend on the availability of supporting information, such as from underside inspections, cores, and other measurements. In other applications, GPR was used to detect and measure moisture accumulation in hot-mix asphalt layers [10]. GPR was also used to evaluate the effectiveness of geosynthetic as a moisture barrier or as a layer separator to prevent migration of fines between layers [11]. Several conventional methods (e.g. excavation, coring, and probing with a hammer and rod) have been used to determine bridge foundation depths and to detect the extent and location of serious flaws to prevent failures under service conditions. These methods are expensive, time consuming, destructive, and limited in their application to the unknown foundation problem. Pile Integrity Testing (PIT) provide the most reasonable, inexpensive, nondestructive, and fastest alternative available to assess the bridge foundations [12-15].

Herein, we integrated the conventional investigation methods (visual condition survey, boreholes, asphalt coring, and standard penetration test) with GPR to evaluate the pavement condition, subgrade moisture damage and assessment of bridge deck deterioration. Study sites are 33 km of the Cairo-Alexandria desert highway (from Kilometer 127 to 160) and Janaklise bridge which located at Kilometer 157 of the highway (Figure 1). We also used the Pile Integrity Test (PIT) to evaluate the bridge foundation. Results of this study used in developing nondestructive and cost-effective measures for pavement rehabilitation, bridge deck deterioration, and bridge pile integrity (Figure 1).