# On the Thermal Stresses Due to Weathering in Natural Stones
## 4 Conclusions  
Natural thermal weathering has challenged engineers to develop resistant materials for application in external environments and to provide models for predicting their long-term behavior. In this paper, we proposed a new methodology by coupling the evaluation of thermal exchanges in building-covering systems to compute the thermal stresses due to daily variations in temperature. The sol-air temperature, which was calculated with parameters measured at the Pescara airport, presented a good correlation with the temperature, which was measured on the external face of a slab at the Pescara Justice Court, even knowing that these two concepts are related, but have different meanings. The peak of the tensile stresses occurred on 10 August at 14:30, and it was of the same order of magnitude as the one proposed by [PERSON] et al. [40], who considered in situ measurements of temperature; however, in our methodology, the stress along the slab presents an almost symmetrical distribution. For gradual changes in temperature, the induced thermal stresses approach those found in almost-steady-state conditions. A non-symmetrical distribution of stress would occur if the temperature changed suddenly. The type of stress (compressive or tensile) and its magnitude depend on the rate with which the gradient of temperature changes between the two sides. The thermal load acting on the facade of the Pescara Justice Court on 8-13 August 2007 was small in comparison with the failure stress of Carrara marble, but it was sufficient to cause the decohesion of calcite grains and deformation, as the bowing phenomenon was verified by previous authors. It must be highlighted that the peak of stress presented in this work was calculated for a specific time, which means that the thermal load floats continuously according to the daily variations in temperature, which would result in continuous loading and unloading cycles throughout the day. In short, the methodology proposed in this paper was efficiently applied for external facades using Carrara marble as the building material, but it can also be applied to evaluate stresses in other structures, such as pavements or roofs, if corrections of the heat exchanges are made. Conceptualization, W.H.I. and T.S. ; Methodology, W.H.I., T.S., J.R., and P.I.B.d.Q. ; Validation, W.H.I., T.S., and P.I.B.d.Q. ; Formal analysis, W.H.I., T.S., and J.R.; Investigation, A.M.F. and M.R.M. ; Data curation, W.H.I., T.S., and J.R.; Funding acquisition, A.M.F. ; Writing--original draft preparation, W.H.I. and T.S; Writing--review and editing, F.V., A.M.F., M.R.M., and P.I.B.d.Q. ; Supervision, A.M.F. and P.I.B.d.Q. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Figure 5: Thermal stresses calculated at 09:15 and at 14:00 on 10 August. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Restrictions apply to the availability of these data. Data was obtained from the Division of Meteorological Services of the Italian Air Force and are available [[http://clima.meteoam.it/RicercaDati.php](http://clima.meteoam.it/RicercaDati.php)]([http://clima.meteoam.it/RicercaDati.php](http://clima.meteoam.it/RicercaDati.php)) with the permission of the Division of Meteorological Services of the Italian Air Force. **Acknowledgments:** The authors are indebted to the Division of Meteorological Services of the Italian Air Force, which provided the meteorological data measured at the Pescara airport in August 2007 used in this paper. Additionally, the corresponding author would like to thank the University of Turin for the financial support during this research. **Conflicts of Interest:** The authors declare no conflict of interest. **Abbreviations**  
The following abbreviations are used in this manuscript: