ABSTRACT
Recent advances in Laser Ultrasonics have the potential to solve this problem on account of higher magnitude of energy (≈1 Joule) and non-contact delivery of energy. This technique have been used to generate ultrasound (Jacobs and Whitcomb, 1997) and study attenuation properties of ultrasound (Owino and Jacobs, 1999). Non-contact detection of ultrasound using Laser Interferometry also have been attempted (Abraham et al., 2011). There is a
1 INTRODUCTION
Civil infrastructure require consistent assessment to maintain their integrity. OECD countries are facing the challenge of maintaining their ageing infrastructure with ever shrinking budgets (Stevens and Schieb, 2007). Traditionally, the monitoring of infrastructure and civil engineering assets have been undertaken through visual inspections (Moore et al., 2001). Surveys on these practices have highlighted their lack of reliability due to a paucity of qualified inspectors. Wave based techniques like ultrasonics can be perused as scientific and accurate alterative to these methods. These technologies rely on the pulses emanating from a site of damage to detect it (Achenbach, 2012). Structures of large lengths can be potentially monitored through this technique (Raghavan and Cesnik, 2007). Using contact type Piezoelectric (PZT or Lead zirconate titanate) transducers and waveguide based ultrasonic techniques, characteristics such as the type(Sharma and Mukherjee, 2015) and setting characteristics of concrete (Sharma and Mukherjee, 2014)can be discerned.
