Concrete Non Destructive Characterisation is one of the important stakes to evaluate the life duration in the present and future civil engineering structures. The damaging modes of the structures often imply the phases of the appearance and after growth of the cracks. We have to detect, identify and characterise them. The characterisation result must lead to a diagnosis of the criticality of a crack regarding the integrity of the structure and its ability to full fill its function. The aim of the present study is to determine the nature of a macro-crack (open or close) visible in surface and to give information on its depth. Two approaches are developed. The first one, based on diffuse ultrasound, provides information about the presence and the depth of an opened crack. The last, based on nonlinear ultrasound, gives information about the presence and the depth of a closed crack.