"The present study is comprised of two separate GPR case studies on a bridge deck and a concrete pavement respectively. These typical concrete structures were investigated using GPR with several objectives: 1) to find the reason of discrepancies between GPR results and the results of the other tests through bridge deck inspection, 2) to investigate the bridge deck under various weather conditions, 3) to determine the relative spatial locations of the imbedded dowel bars in the new concrete pavement, and finally 4) to evaluate the present capabilities of GPR technology including survey scheme and analysis through these two case studies."--Abstract, p. iii.

" TRB's second Strategic Highway Research Program (SHRP 2) Report S2-R06A-RR-1: Nondestructive Testing to Identify Concrete Bridge Deck Deterioration identifies nondestructive testing technologies for detecting and characterizing common forms of deterioration in concrete bridge decks.The report also documents the validation of promising technologies, and grades and ranks the technologies based on results of the validations.The main product of this project will be an electronic repository for practitioners, known as the NDToolbox, which will provide information regarding recommended technologies for the detection of a particular deterioration. " -- publisher's description.

More than a third of America's bridges are considered substandard--either structurally deficient, functionally obsolete or both. Offers first-rate, practical guidance regarding the inspection and rehabilitation of aging bridge infrastructure including all elements involving structure, various materials and design types. Features seismic retrofit and coverage of environmental issues. Each chapter is written by an authority on the subject. Contains top-quality, detailed line illustrations plus photographs of actual rehab projects.

Discusses techniques that require physical measurement for inspection, and/or monitoring of structures.

Advanced nondestructive inspection techniques like stress wave timing and resistance microdrilling have been used to successfully inspection timber bridges, but it is most effective on girder style bridges. There is a noted need to develop additional inspection techniques for longitudinal deck/slab timber bridges, which comprise about 20% of the national bridge inventory. One technique that holds potential is ground penetrating radar, a recognized nondestructive testing technique that has been used effectively for many different environmental and transportation applications. It has been utilized successfully to identify buried objects, internal defects and material changes. The objective of this research was to assess the potential for using GPR to identify and assess simulated deterioration in longitudinal timber deck timber bridges. GPR scans were completed in the longitudinal and transverse directions of a screw laminated timber bridge deck before and after a bituminous layer was added to assess embedded defects that simulated voids, decay, insect damage and horizontal shear splitting. Assessment of the GPR wave energy signal was completed using visualization software that was provided with the commercial GPR unit used for the testing. The radar signal was analyzed in both the longitudinal direction (antenna front to back) and the transverse direction (antenna side to side). Interpretation of the radar signals allowed for the identification of various internal defects present in the deck. Based on the results, GPR has the potential to identify internal defects in timber bridge decks before and after a bituminous layer was added. Large, rectangular void defects (at least 6‐ by 12‐ by 5 in. (15.2‐ by 30.4‐ by 12.7 cm)) that were hollow, filled with foam, or filled with sawdust/adhesive were most easily identified under all scanning conditions. The addition of a bituminous layer, common to slab bridge construction, damped the signal response and made it more difficult to identify defects. Several smaller defects that were found in the deck without a bituminous layer were not identified in scanning completed after the bituminous layer was added.

An objective view of the relative advantages and limitations of the nondestructive testing and evaluation methods that are currently used in the inspection of bridge decks is presented and discussed. The three main nondestructive testing technologies that were evaluated are impact-echo, ground penetrating radar, and infrared thermography. Nondestructive testing and evaluation procedures, including methodology and equipment to evaluate concrete bridge decks with asphalt overlays, are also presented and discussed. Current results indicate that a combination of ground penetrating radar and infrared thermography would provide the best methodology for evaluating the structural integrity, e.g., delaminations, of concrete bridge decks with overlays. Furthermore, current results also indicate that the impact-echo method shows promising future development towards the nondestructive evaluation of bridge superstructures.

During the week of June 14, 1982, Donohue & Associates, Inc. performed an infrared thermographic scan of 19 bridges and 1 section of continuously reinforced concrete pavement. The bridges and pavement were located throughout the northwest quarter and central portion of. Iowa. The scanning was undertaken under various environmental conditions to evaluate the technique under typical conditions. During the data collection phase surface temperatures were measured with a digital contact thermometer. Temperature measurements were taken in delaminated and solid areas. The ability to detect delaminations accurately is dependent upon the temperature differential between the solid and delaminated pavement. The larger the temperature differential the easier it will be detected by the infrared scanner. The temperature differential is dependent upon the depth of the delamination, amount of separation at the delamination, and environmental conditions. The environmental conditions under which the data was collected is summarized on Table 2 along with the temperature differentials between the solid and delaminated pavement. The environmental conditions varied on each of the five days that data was collected. These conditions together with the range of temperature differentials are shown in Table 3.

The Iowa Department of Transportation initiated this research to evaluate the realiability, benefit and application of the corrosion detection device. Through field testing prior to repair projects and inspection at the time of repair, the device was shown to be reliable. With the reliability established, twelve additional devices were purchased so that this evaluation procedure could be used routinely on all repair projects. The corrosion detection device was established as a means for determining concrete removal for repair. Removal of the concrete down to the top reinforcing steel is required for all areas exhibiting electrical potentials greater than 0.45 Volt. It was determined that the corrosion detection device was not applicable to membrane testing. The corrosion detection device has been used to evaluate corrosion of reinforcing steel in continuously reinforced concrete pavement.