C.BOSCO, Turin Polytechnic
E.CADONI, CEC Joint Research Centre, ISPRA
and M.FACCHINI, CEC Joint Research Centre, ISPRA and Loughborough University

Structures require periodic inspection to verify their safety condition, for maintenance and to plan their repair. For this purpose the experimental behaviour and the characterization of materials used in buildings can be very important. Recently optical interferometric techniques have acquired more and more importance in non-destructive testing and can be used as alternative or complementary tools to classical techniques. In the paper the authors describe the application of Electronic Speckle Pattern Interferometry to the determination of the strain intensification at the tip of a crack that propagates in a. simply supported specimen of clay material loaded at its midspan.