Evaluation of permanent 3D printed formwork of a bridge pier using non-destructive testing methods

In recent years, 3D concrete printing (3DCP) has emerged as a promising method for automated construction. One of the main challenges of 3DCP today is the problematic placement of rebars, which complicates the creation of load-bearing structural elements. One way to address this problem is to use 3DCP elements as permanent concrete formwork. Although this method has been utilized in several engineering projects, there remains a very limited number of studies on the quality control and evaluation of structures with 3DCP permanent formwork. In the study presented, we applied several elastic-wave-based methods of Non-Destructive Testing (NDT) for the evaluation of 3DCP permanent formwork of a bridge pier, whose footing was constructed using such formwork. The results showed that, using methods of NDT, it is possible to detect and evaluate defects in the 3DCP formwork and the quality of bonding between the 3DCP permanent formwork and the post-cast concrete. • The degree of internal deterioration in 3DCP formwork panels was evaluated using elastic wave methods. • Delamination was detected within cracked panels using these methods. • The findings were consistent with results from hammering tests and endoscopic inspections. • Elastic wave methods can effectively visualize internal deterioration in 3DCP.