ên13th International Conferenceon Fracture June 16–21, 2013,Beijing, China -2- 2. Fatigue The degradation process by fatigue is linked to deterioration under cyclic loading which leads to the emergence and development of microcracks or microfissures on the pre-existing material, and may cause rupture of the structure. The higher the stress level used, the lower the number of cycles achieved, and thus more rapidly deteriorate the mortar by fatigue, for the same frequency of loading. Coating systems are subject to an increase of stress due to temperature differences between the top and bottom of the wall and the coating system, causing large thermal differential that origin the warpage of the coating. For the static fatigue analysis breakthrough curves are usually used that can be adapted to cyclic loading. In the analysis of fatigue strength material such as mortar which is a brittle material a classical curve that may be used is the Mohr-Coulomb curve. This curve defines the fatigue resistance of the material and the expected life of the material can be used with the stresses generated by the thermal shock on the system, and indicate whether there is a risk of collapse due to fatigue mortar. 3. Characterization of mortar In this work the mortar ACII Votomassa was used, prepared according to the manufacturer's recommendations. 3.1. Definition of the body-of-evidence Fatigue tests in compression, body-of-proof cylindrical 10x20cm were chosen according to the study by SUELEN, 2009. Figure 1 - Mechanism to support the fatigue test and compression test specimen. 3.2 Fatigue Testing The fatigue test consists in applying a cyclic compression load on a body-of-evidence in order to measure how many cycles the body-of-evidence resists before rupturing. Thus, we obtain the Wöhler curve or SN curve. This assay is also capable of supplying a characteristic alternated stress for each material, below which the body of the test piece no longer breaks. The main results of this assay are: Narrow fatigue resistance (σRf), ie the alternating stress value below which the body of
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