## 1 Introduction  
Thermal damage in cementitious composites represents a topic of key interest for controlling strength, durability and serviceability conditions of concrete structural components [1]. The most relevant thermo-physical and mechanical properties of cement-based composites (i.e., cohesion, friction, stiffness, strength, cracked configurations and durability parameters) suffer severe degradation as a result of long-term exposure to high temperatures [2; 3]. Many factors influence the thermo-hygro-chemo-mechanical response of cement-based composites, which can be grouped in two main categories [4]: (i) the material or composite factors and (ii) the environmental (conditioning) factors. The first one deals with the dehydration processes in the hardened cement paste due to high temperatures [5] and with the characteristic meso-structure of the composites under investigation, such as presence of inclusions (aggregates), aggregate-matrix bonds, air bubbles/voids, fibers, etc., which leads to incompatibility of strains among components under a thermal process [6]. The second one deals with environmental and/or conditioning factors such as rate, duration, i.e., thermal history, exposure and distribution of the heating/cooling process together with the considered loading conditions which also influence the thermal effects and induced damages [7]. Many researches have already been performed with focus on the thermo-hygro-mechanical properties of cementitious composite materials affected by high temperature at several scales of applications. Recent works investigated the effect of using by-products for modifying the residual strength after high temperature exposure [8; 9; 10]. Some works also highlight how the addition of (nano- [11], micro- [12] and macro- [13; 14]) fibers can improve the residual strength of components and structures after high temperatures exposures. In the literature, numerical procedures are also available for describing the physico-mechanical processes resulting from the exposure to high temperatures in cement-based composites like different types of concretes and mortars. The most classical examples in this field are those based on a further development of the well-known smeared crack procedure to deal with the thermo-mechanical behavior of concrete [15; 16; 17]. Advanced models dealing with meso-scale descriptions [18; 19; 20], multi-physics [21] and multiscale approaches [22] are also available in this matter. It should be mentioned that, so far, only a few of the mentioned models are capable to accurately describe the complex response of cementitious materials under high temperatures. In this sense, it is imperative the need for an extensive experimental database that covers not only the thermo-hygro behavior of cement-based compounds but also their mechanical response when subjected to a complete spectrum of stress states including the effect of high temperatures and documenting the strain response including pre and post peak behavior. Regarding mortars, it is well known that their mechanical response is highly dependent on the applied confinement level and this is a crucial factor to be included into constitutive relationships [23] even more they are under high temperatures, particularly over 300 \({}^{\circ}\)C. The most recent works are related, on one hand, to the study of mechanical response of mortars under different confinement levels at ambient temperature [24; 25] and, on the other hand, to residual peak strengths at different levels of high temperatures but they rarely present the complete stress-strain curves including lateral and/or volumetric strains [4; 26; 27; 28; 29; 30; 31]. The main objective of this work is to contribute with additional experimental data involving the incidence of temperature on cement mortars having different qualities. Therefore, the results of an experimental campaign aimed at investigating the damage caused by the action of elevated temperatures on the physical and mechanical properties of normal and high strength mortars are presented.