In the past century, precast reinforced concrete has become the most widely used construction material in infrastructure engineering, especially for long-span structures. Nowadays, a growing research area concerns the assessment of concrete strength degradation due to environmental exposure and reinforcement corrosion. This paper reports an experimental campaign on some prefabricated concrete elements that were exposed to atmospheric agents for approximately 20 years. The campaign took the uncommon opportunity to access the full inspection and sampling of rebar. The included activities had different invasiveness and encompassed inspections, core sampling, corrosion potential mapping, compressive strength tests, as well as neutralization depth assays on cored surfaces, on chisel-split surfaces, and on drilling powders. The results bring together a global diagnostic picture of very limited degradation and of elements that are fully able to attend their design service life; the latter is estimated to be considerably higher than 20 years and to exceed 75 years if the concrete mix does not show quality issues. Results also permit drawing considerations on a hierarchy of diagnostic reliability in the evaluation of RC degradation, in which concrete core sampling plays the role of golden standard.
1 January 2019 in International Journal of Masonry Research and Innovation
The masonry have been studied with idealistic model, for historical masonry of a centuries-old building, it is really difficult to apply the above said simplifications, the intriguing rules deduced from laboratory studies and also the numerical patterns are more and more sophisticated. Below are some considerations made in reference to a specific case study: Palazzo Ducale in Parete, of Caserta province. In this palace, it was quite impossible to imagine a model which could faithfully reflect the masonry history of over a thousand years. Some extremely simplified approaches are able to provide information about the capacity of the structure. Furthermore, results from nonlinear static analyses are presented. Indications on the congruence between codes rules and results from numerical analyses performed according to the Italian seismic code are supplied. The results show that generally imposing the best approach for the generic case could not be satisfying for the particular one.
Acoustic Emission is a non-invasive technique with potential applications in Structural Health Monitoring (SHM), particularly for assessing historic masonry structures. However, its use in this field is complex due to the heterogeneous nature of masonry, where variations in density, mortar joints, and internal discontinuities influence signal propagation, leading to attenuation and distortion that complicate damage detection and localization. Nonetheless, AE can offer qualitative insights into damage initiation and progression, serving as a complementary approach to traditional monitoring methods. This study explores the feasibility of AE through an in-field test conducted on the historic Santa Maria delle Grazie complex, assessing its ability to capture qualitative indicators of structural behaviour. By integrating AE results with data from conventional monitoring instruments, a comprehensive interpretation of the load test outcomes was developed despite the challenges posed by the irregularities of ancient masonry. The findings contribute to the ongoing evaluation of AE as a diagnostic tool and highlight its potential role in heritage conservation strategies.