The purpose of this study was to identify the currently available nondestructive evaluation technology that holds the greatest potential to detect moisture in flexible pavements and then apply the technology in multiple locations throughout Virginia. Ground-penetrating radar (GPR) was chosen for use in a field investigation because of its ability to measure large areal extents and reports of successful implementation by other researchers. This technology was used to determine the moisture content of the subgrade beneath five flexible pavement sections in Virginia. The GPR survey was conducted at normal driving speeds, and data were collected at a sampling rate of 1 scan per foot. For each site, three scans were collected in the travel lane (in the right wheel path, the center of the lane, and in the left wheel path). Existing passing lanes were also scanned. Initial data processing subdivided each pavement section into a three-layer system composed of the hot-mix asphalt layers, the aggregate base layers, and the subgrade. The processing also included calculating the dielectric constant of each layer. These raw data were used to conduct further analyses considering data from only the subgrade. The data were normalized to highlight those areas with the highest dielectric constants since it is known that moisture will have the greatest influence on the dielectric properties of the material. This study showed that GPR can identify areas of varying dielectric constant attributed to variations in the moisture content of the subgrade of various pavement sections. The use of the GPR offered a safe and rapid means for nondestructively surveying large areas of pavement as the survey was conducted at normal driving speeds. In addition, the use of a statistically based data normalization procedure allowed GPR to be used to assess qualitatively the moisture condition of the subgrade of flexible pavements. Two advantages of GPR testing are that it can be used to provide a continuous reading of subgrade moisture conditions (rather than a point location) and can be performed at highway speeds with no traffic control. A typical network-level study involving one subgrade bore per mile would cost $1,200 per location. The cost for the current study averaged $0.04 per data point. Assuming one data point every foot and three scans per lane, the resultant cost was approximately $680 per mile. VDOT maintains approximately 225 lane-miles of flexible pavement with subsurface drainage layers and does not routinely inspect the condition of the outlet pipes. In approximately 1 workday, a two-person crew could use a push camera to inspect approximately 5 lane-miles worth of outlet pipes for subsurface drainage layers or the GPR system could scan approximately 330 lane-miles (assuming operation at 55 mph for 6 hours). Thus, the entire system of flexible pavement with subsurface drainage could be inspected in approximately 2% of the time.

In the recent past, new materials, laboratory and in-situ testing methods and construction techniques have been introduced. In addition, modern computational techniques such as the finite element method enable the utilization of sophisticated constitutive models for realistic model-based predictions of the response of pavements. The 7th RILEM International Conference on Cracking of Pavements provided an international forum for the exchange of ideas, information and knowledge amongst experts involved in computational analysis, material production, experimental characterization, design and construction of pavements. All submitted contributions were subjected to an exhaustive refereed peer review procedure by the Scientific Committee, the Editors and a large group of international experts in the topic. On the basis of their recommendations, 129 contributions which best suited the goals and the objectives of the Conference were chosen for presentation and inclusion in the Proceedings. The strong message that emanates from the accepted contributions is that, by accounting for the idiosyncrasies of the response of pavement engineering materials, modern sophisticated constitutive models in combination with new experimental material characterization and construction techniques provide a powerful arsenal for understanding and designing against the mechanisms and the processes causing cracking and pavement response deterioration. As such they enable the adoption of truly "mechanistic" design methodologies. The papers represent the following topics: Laboratory evaluation of asphalt concrete cracking potential; Pavement cracking detection; Field investigation of pavement cracking; Pavement cracking modeling response, crack analysis and damage prediction; Performance of concrete pavements and white toppings; Fatigue cracking and damage characterization of asphalt concrete; Evaluation of the effectiveness of asphalt concrete modification; Crack growth parameters and mechanisms; Evaluation, quantification and modeling of asphalt healing properties; Reinforcement and interlayer systems for crack mitigation; Thermal and low temperature cracking of pavements; and Cracking propensity of WMA and recycled asphalts.

"TRB's National Cooperative Highway Research Program Report 747: Guide for Conducting Forensic Investigations of Highway Pavements explores a process for conducting forensic investigations of pavements that is designed to help understand the reasons behind premature failures or exceptionally good performance. The process also allows for the collection of data for use in developing or calibrating performance-prediction models. The report includes example forms and checklists for use during the conduct of an investigation. These forms can be modified to suit the particular requirements and procedures for the agency. The example forms are included with the print version of the report in CD-ROM format." --Publisher description.

Ground penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in non-destructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR for NDT has been successfully introduced in a wide range of sectors, such as mining and geology, glaciology, civil engineering and civil works, archaeology, and security and defense. In recent decades, improvements in georeferencing and positioning systems have enabled the introduction of synthetic aperture radar (SAR) techniques in GPR systems, yielding GPR-SAR systems capable of providing high-resolution microwave images. In parallel, the radiofrequency front-end of GPR systems has been optimized in terms of compactness (e.g., smaller Tx/Rx antennas) and cost. These advances, combined with improvements in autonomous platforms, such as unmanned terrestrial and aerial vehicles, have fostered new fields of application for GPR, where fast and reliable detection capabilities are demanded. In addition, processing techniques have been improved, taking advantage of the research conducted in related fields like inverse scattering and imaging. As a result, novel and robust algorithms have been developed for clutter reduction, automatic target recognition, and efficient processing of large sets of measurements to enable real-time imaging, among others. This Special Issue provides an overview of the state of the art in GPR imaging, focusing on the latest advances from both hardware and software perspectives.

"TRB's National Cooperative Highway Research Program Report 747: Guide for Conducting Forensic Investigations of Highway Pavements explores a process for conducting forensic investigations of pavements that is designed to help understand the reasons behind premature failures or exceptionally good performance. The process also allows for the collection of data for use in developing or calibrating performance-prediction models. The report includes example forms and checklists for use during the conduct of an investigation. These forms can be modified to suit the particular requirements and procedures for the agency. The example forms are included with the print version of the report in CD-ROM format." --Publisher description.

Ground-penetrating radar (GPR) is a rapidly developing field that has seen tremendous progress over the past 15 years. The development of GPR spans aspects of geophysical science, technology, and a wide range of scientific and engineering applications. It is the breadth of applications that has made GPR such a valuable tool in the geophysical consulting and geotechnical engineering industries, has lead to its rapid development, and inspired new areas of research in academia. The topic of GPR has gone from not even being mentioned in geophysical texts ten years ago to being the focus of hundreds of research papers and special issues of journals dedicated to the topic. The explosion of primary literature devoted to GPR technology, theory and applications, has lead to a strong demand for an up-to-date synthesis and overview of this rapidly developing field. Because there are specifics in the utilization of GPR for different applications, a review of the current state of development of the applications along with the fundamental theory is required. This book will provide sufficient detail to allow both practitioners and newcomers to the area of GPR to use it as a handbook and primary research reference.*Review of GPR theory and applications by leaders in the field*Up-to-date information and references*Effective handbook and primary research reference for both experienced practitioners and newcomers

Recognized and advocated as a powerful tool, the role of remote sensing in identifying, mapping, and monitoring soil salinity and salinization will continue to expand. Remote Sensing of Soil Salinization: Impact on Land Management delineates how to combine science and geospatial technologies for smart environmental management. Choose the Right Tech