Laser ultrasonics for civil engineering : some applications in development for concrete non destructive testing

Abstract

Non destructive testing of civil engineering infrastructures is becoming of primary importance for their diagnosis, residual time life estimation and/or structural health monitoring. A particularity of civil engineering application is the large size of the survey zones and the expected low cost of inspection. In this context non contact ultrasonics may offer the possibility to built robots that can automatically scan large areas (or eventually be integrated in moving vehicles) to recover mechanical properties of material or to perform imagery for geometrical information recovery. In this paper we present two possible applications of in situ laser ultrasonics : one is the detection of voids in tendon duct with the impact echo method, the other is the use of surface waves to recover mechanical properties of the first centimetres of concrete structures (here after called cover concrete).