In-depth defect inspection of precast double walls using non-destructive techniques

Precast double walls are frequently used for building applications and consist of a pair precast reinforced concrete shells connected by lattice girder creating an inner cavity. Once placed at its final position this cavity is filled with freshly cast compacted concrete. Aside from benefits such as increased ease in installation, reduced cost shorter construction time also some pitfalls recognized. Due to the restrained space presence truss undesired defects (e.g. voids, honeycombing, etc.) might occur without being noticed, outer wall elements act formwork. This actually reduce load capacity jeopardize structural integrity structure. Therefore, different non-destructive tests order assess filling degree localize defects, varying success ratio (i.e. detectability). Different techniques were applied on test intentionally embedded (polystyrene blocks) diameter: rebound hammer, ultrasonic pulse velocity via direct transmission, shear-wave tomography, ground penetrating radar active infrared thermography. The limits these depth defect localization discussed paper. effect selected detection method surface-on-depth itself has detectability.