Diagnosis of historic reinforced concrete buildings. A literature review of non-destructive testing (NDT) techniques

Non-destructive testing (NDT) techniques are employed by many authors as reliable and effective methodologies to investigate the current conservation state of historic buildings and to follow up its evolution in response to the surrounding environmental changes. This paper briefly reviews the scientific articles dealing with NDT techniques applied to historic reinforced concrete (RC) buildings. To this purpose, 32 articles were selected through the steps of the Preferred Reporting Items for Systematic Review and Meta- analyses (PRISMA) flow diagram and critically analysed. It emerges that Acoustic Emission and Ultrasonic techniques, Thermography, Rebound Hammer, and Electromagnetic techniques (e.g., Eddy Current and Ground Penetrating radar) are commonly employed due to their ability to detect damage in RC structures. As a result, the combined use of acoustic and mechanical methods (also known as “SonReb” Rebound Hammer and Ultrasonic Pulse Velocity) is found to be the approach more frequently used in the revised documents. This work allows to guide in the selection of NDT techniques to study the rate of decay, if any, and shows the way towards the development of new early warning approaches for historic RC structures.