Condition Evaluation of Concrete Bridges Relative to Reinforcement Corrosion.Volume 3. Method for Evaluating the Condition of Asphalt-Covered Decks

摘要

State highway agencies need a nonintrusive means of evaluating the condition ofasphalt-covered concrete bridge decks for reinforcement corrosion. Information on the condition of the concrete deck is needed in order to estimate service life, to program rehabilitation and maintenance activities, and to estimate quantities for rehabilitation contracts. This volume describes the development of a technique for nondestructively determining the presence of delaminations at the top and bottom reinforcement levels. This technique employs the use of short pulse, ground-penetrating radar. Extensive radio frequency modeling of the bridge deck scenario was carried out to establish theoretical limits of parameters and capabilities. Field testing on 22 bridges in Virginia, New York, and Vermont provided the empirical data for the evaluation of various deterioration discriminants in order to identify those providing optimum prediction capabilities. Ground truth data in the form of cores (in the cases where the asphaltic concrete was subsequently removed for repair purposes), chain drag sounding, and actual repair areas were also collected on the bridge sites. The best descriminant for delamination at the top reinforcement level is signal attenuation, and at the bottom level, increase in the amplitude of the bottom reinforcement bar signal. Advanced radar data acquisition and signal processing equipment and software were also developed to provide a useable system at the practical level.