Non-Destructive Inspection of Concrete Structures Using an Acceleration Pickup

The present paper proposes a method for detecting cracks or honeycombs in concrete structures using an acceleration pickup. The sensor on the concrete surface observes the stationary waves which are generated inside the structures depending on the depth of the crack (if there is a crack) or the bottom of the structure (if there are no cracks or honeycombs). The method measures the depths of the reflection planes (such as cracks or honeycombs) accurately by modeling the sensor output as an output of a linear dynamic system with unknown parameters and by applying a maximum likelihood method. The method is shown to be quite effectively applied to measure the depths of cracks and honeycombs