Multiple Complementary Nondestructive Evaluation Technologies for Condition Assessment of Concrete Bridge Decks

Abstract

Reinforced concrete bridge decks are exposed to several types of deterioration processes: corrosion, alkali–silica reaction, carbonation, shrinkage, freeze–thaw actions, and so forth. The most commonly found problem is corrosion-induced bridge deck delamination. Previous studies have shown that surveys of bridges relying on a single nondestructive evaluation (NDE) technology provide limited information about the condition of concrete bridge decks. To overcome limitations of individual technologies, a complementary approach using several NDE technologies should be used in bridge deck evaluation. The presented approach utilizes a suite of NDE technologies, namely, impact echo (IE), ultrasonic surface waves (USW), ground-penetrating radar (GPR), half-cell potential (HCP), and electrical resistivity (ER). The suite of NDE technologies was implemented in the evaluation of bridge decks on nine bridges in Iowa. The NDE was complemented by ground-truth measurements on the cores extracted from all nine bridge decks. Condition assessment with the five NDE technologies has clearly shown their advantages and limitations. For example, the GPR surveys provided assessment of concrete deterioration at relatively high speeds of data collection. In contrast, IE provided high accuracy in detection and characterization of delaminations in the deck but at a lower testing speed. HCP and ER tests provided assessment of the likelihood of corrosion, whereas the USW test provided accurate assessment of the effects of deterioration processes and defects on mechanical properties, primarily the degradation of the elastic modulus. Most important, the survey showed the advantages of use of multimodal NDE surveys in the comprehensiveness of condition assessment of concrete bridge decks.