A Preliminary Study on Application of AE Methods to Detecting Aggregation Regions of RC Bridge Decks

Nowadays, numerous “aggregation” problems are reported in existing RC bridge decks. Since aggregation is known as a main factor that decreases the serviceability and safety of the decks, it is highly demanded to detect and recover it as early as possible. However, those regions are invisible from asphalt pavement surfaces, so the aggregation parts are recognized after severely deteriorated. Facing this challenge, this study is devoted to develop a nondestructive testing method that the aggregation regions can be detected from asphalt pavement surfaces by capturing the acoustic emissions (AE) under traffic loads. As a preliminary experimental study, a laboratory-scale specimen was conducted with one end equipped with and the other end without modelled aggregation regions. From incremental cyclic loading tests, it is verified that, firstly, the aggregation regions may yield a great amount of AE activities, significantly more than the non-aggregation regions, under loads of similar order to traffic loads, and, secondly, most measured AE waves, dominated by low frequencies, are those likely caused by the frictions between aggregated particles.