Drilling resistance measurement as innovative testing method for strength assessment of concrete structures

In civil engineering, the assessment of concrete structures is essential for ensuring safety, guiding maintenance, and extending service life. The traditional destructive testing method, i.e. core extraction, although accurate, damages the structure, and is time-consuming and expensive. Non-destructive testing (NDT) methods like ultrasonic pulse velocity and rebound hardness tests have addressed some of these issues but often fall short in detecting subsurface degradation and characterising in-depth concrete properties. Drilling resistance (DR) has emerged as a promising semi-destructive testing technique capable of generating high-resolution resistance profiles with depth. This review consolidates the current state of research on DR applied to concrete structures, examining its operational principles, influencing parameters, and sensitivity to material and environmental conditions. Comparative analysis with established NDT methods is provided to highlight DR advantages and limitations. Applications in structural condition monitoring, particularly for ageing concrete structures, are discussed. Finally, the review identifies current research gaps and outlines potential future directions for advancing DR technology. By analysing existing knowledge, this work aims to position DR as a promising method within the broader context of concrete diagnostics.