Evaluation of NDT Methods for In Situ Documentation of Concrete for Reuse: Laboratory Studies

Concrete production has significant environmental impacts due to extensive raw material use and high CO₂ emissions. Reusing structural concrete elements can potentially reduce these environmental impacts by reducing the demand for new production. However, reliable and practical documentation of concrete properties is needed for safe and scalable reuse. Although several non-destructive testing (NDT) methods show promise for in situ assessment of concrete properties, a clear gap remains in implementing them into a comprehensive approach for reuse documentation. This study investigates the potential of combining ultrasonic pulse velocity (UPV), rebound hammer (RH), and electrical resistivity (ER) methods for documenting concrete properties for reuse. Several parameters relevant to reuse scenarios, such as saturation level and aggregate type and size, were systematically evaluated to understand their impact on NDT documentation of concrete for reuse. NDT documentation of compressive strength and chloride migration coefficient was assessed on 120 cylindrical specimens. Fifteen concrete mixtures were used with three aggregate compositions and five water-cement ratios. The experimental results are discussed in the context of in situ documentation of structural elements in donor buildings to ensure the practical applicability of the findings. The findings show that these NDT methods can potentially document the properties of concrete reliably and practically, thereby addressing the lack of in situ documentation procedures needed to enable the safe and scalable reuse of structural elements.