## 6 Conclusions  
In this work, the results of an extensive experimental campaign aimed at evaluating some relevant physical and mechanical properties of normal (MNS) and high strength (MHS) cement mortars after the exposure to high temperatures were presented. The considered mortar types are related with normal and high strength concretes with compressive strengths of 30 and 80 MPa, respectively. Prior to the physical and mechanical tests, mortar samples were thermally treated considering seven levels of temperature, ranging from 20 to 600 \({}^{\circ}\)C. Then, weight loss and capillary water absorption were measured. Finally, uniaxial compression, splitting tensile and flexural tests were performed in residual state. In the following, the main obtained conclusions are pointed out, which are certainly limited to the considered materials and conditions.  
* Physical properties: Specific weight loss was similar for both mortar types at low temperatures (100 \({}^{\circ}\)C and 200 \({}^{\circ}\)C). However, for mid-to-high ranges of temperature exposures, MHS achieved higher relative weight losses than MNS. In turn, MNS showed a much higher capillarity water absorption than MHS samples. Increasing temperatures produced increasing water absorption coefficients, evidencing the thermal damage causing an increase in the accessible porosity. However, that increase was almost linear for MNS, while for MHS it was substantially more evident from low-to-medium temperatures (up to 300\({}^{\circ}\)).
* General conclusions regarding physical tests: The results demonstrated the fundamental role of the \(w/b\) ratio in the absorption response of cement composites and consequently, in durability. At ambient temperature, the smaller accessible porosity of high strength mortars indicates a higher performance in comparison to normal strength mortar. However, under the action of increasing temperatures, the thermal damage causes the formation of micro cracks, generating further connection of the closed porosity and consequently, allowing the water, initially trapped in closed porosity, to emigrate and evaporate. As result, the internal porosity structure of lower \(w/b\) ratio mixtures are more affected by the action of temperature.
* Compressive and tensile strengths: In all cases, strengths suffered a progressive degradation due to temperature. While at low to medium temperatures, strength loss resulted similar for both mortar types, at the highest temperature, MNS presented a higher relative loss of strength than that of MHS. It was also observed that the loss of tensile strength after the exposure to the highest temperatures was higher in comparison to the loss of compressive strength.
* Uniaxial compression: The action of temperature caused in all cases a decrease of Young's Modulus and an increase in the strain corresponding to peak load. The MHS showed a much more brittle behavior in comparison with that of the MNS, for all the considered temperatures. Samples of both mortar types that were not exposed to temperature, almost did not show a critical stress where volume begins to increase instead of decrease. On the contrary, after the action of temperature, the corresponding stress-volumetric strains curves did present a turning point, showing a behavior similar to that of concrete.  
Future works related with the experimental results presented in this paper include the numerical analysis of the mesoscopical behavior of concrete considering the mortar relevant properties and taking into account the mortar quality.  
Conceptualization, A.C., M.R., H.X. and P.F.; experimental tests: H.X. and M.R.; data processing: M.R., I.L, K.B. and P.F.; writing--original draft preparation, A.C. and P.F.; project administration, P.F. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Universidad de Buenos Aires, UBA, grant number UBACyT 2018 20020170200382 BA.