Combined while-drilling techniques for the assessment of deteriorated concrete cover

In this paper the idea of monitoring the resistance encountered while taking a sample from a concrete structure and to combine this data with the analysis of the extracted material has been regarded as a method for detecting the possible deterioration of the concrete cover. In the common case of core drilling, the time spent for a unit penetration proved to be a good indicator of the local material response. Hence, the laboratory analyses can be easily integrated with this preliminary scan of the material quality, which comes at no cost once the acquisition of samples has been planned. On the other hand, hammer-drilling of small holes is a definitely faster and less invasive alternative for inspecting the mechanical response at increasing depth within the cover. Although this method is not intended to provide a material sample, the analysis of the ground-concrete powder and the visual inspection of the remaining hole proved to be a viable alternative to the traditional examination of cores.