## 4 Conclusions  
This paper presented an experimental study about the effects of exposure to elevated temperature on the remaining properties of mortars produced with different insulating aggregates. In general, the physical and mechanical behavior of the thermal mortars was influenced by such exposure: the results obtained, together with the properties of the aggregates (reported in the literature), show that the variation of the mechanical behavior of the thermal mortars (increase and decrease of mechanical strength) is mainly due to the effect of temperature on the cement paste. In addition, the changes in aggregate porosity due to temperature exposure may cause changes in the mechanical strength of the mortars, as is the case of expanded clay.  
The results obtained also show that the most sensitive mortars to the effect of temperature are the ones with admixtures (C\({}^{\text{AERO}}\) and E\({}^{\text{AD}}\)). Regarding aerogel mortar (C\({}^{\text{AERO}}\)), despite incorporating an aggregate that resists to high temperatures _per se_, its binder paste, which incorporates admixtures, led to a worse performance after exposure to high temperatures. This behavior is confirmed by the worse performance of the sand mortar with admixtures (E\({}^{\text{AD}}\)), when compared to the reference mortar (D\({}^{\text{ref}}\)) without admixtures. Even so, mortar with aerogel was the one that showed the lowest variation in thermal conductivity with increasing temperature.  
The exposure to high temperatures had a reduced influence on the correlations between different physical and mechanical properties of the mortars studied; this shows that in general exposure to elevated temperature affects the properties of the mortars in a similar way.  
Overall, the results obtained show that the mortars with thermal insulation properties studied in this paper are suitable for application in exterior and interior wall coverings. Although they tend to maintain their insulating characteristics when exposed to high temperatures, they undergo internal changes that affect their mechanical strength when exposed to temperatures of 100 \({}^{\text{C}}\) and above.  
In summary, after being exposed to elevated temperatures, the thermal mortars were able to maintain their insulating characteristics, but experienced internal damage and reduction of their mechanical properties. Therefore, in the case of current exposure to elevated temperatures (e.g., in specific industrial applications), it may be necessary to incorporate specific materials (e.g., additions) in these mortars in order to guarantee enhanced resistance to high temperatures.  
Figure 16: Relationship between compressive strength and thermal conductivity.  
**Author Contributions:** [PERSON] did the experimental program and wrote the first draft of the paper; [PERSON] improved the paper, namely the literature review and the discussion of results; [PERSON]-[PERSON] supervised the experimental work, reviewed and edited the paper; [PERSON] supervised the work and reviewed the paper. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by FCT grant PTDC/ECM/118262/2010, NANORENDER research project.  
**Acknowledgments:** The authors acknowledge the financial support provided by CERIS research center, FCT (Foundation for Science and Technology) and COMPETE 2020: FCT Project PTDC/ECM/118262/2010, NANORENDER (2012-2015); FCT PhD Grant SFRH/BD/97182/2013; COMPETE 2020 Project \"PEP--Parede Efficiente Plus\" (POCI-01-0247-FEDER-017417). The authors also acknowledge the following manufacturers and companies: Weber, Argex, Corticeira Amorim and SECIL.  
**Conflicts of Interest:** The authors declare no conflicts of interest.