This paper presents a study in wear tests with a gneiss from Santo Antônio de Pádua/RJ/BR and includes analysis of the rotation increase by testing Slake Durability (SD) and Micro-Deval (MD) tests. To evaluate the influence of the rotation in these tests was set up laboratory equipment that allows varying the speed of 7 rpm to 238 rpm. This study could be implemented in wide variety of rock materials and thus target it according to their lifetime in the project. With varying the wear levels it was observed increasing weight loss until the inertia moment holding the specimens in the wall of the machine. The results indicate an increase in linear mass loss. These procedures allow a more precise analysis of durability at a range approximately from various regions of the world.
The civil engineering studies to evaluate of the durability characteristics in rock materials are common to use wear tests. In these test there is a relationship between the rotation speed of the degradation drum and the material durability characteristics. The determination of this relationship is fundamental for characterization a material in the long term, considering that the rotation speed is related to the energy of environmental degradation.
Among the existing building materials, highlight particular deserve the rocks by the frequent use in the projects. According to Salles & Maia (2004), these materials before they are extracted from mines or quarries, it presents in a balanced alteration state with the environment, which was achieved in a geological time-interval, that is, from hundreds to thousands of years. After extraction and application in a work, change occurs in the middle. Then, the rock begins to undergo transformations seeking a new equilibrium condition. The speed of change in the new environment depends on the rock susceptibility to alteration, in the others words, the alterability. Thus, the rock alterability will depend on the material characteristics, the external environment and the exposure time. Depending on the alterability characteristics, the rock can change it in an interval of time that can vary from thousands of years to a few months.
This paper presents the wear results of gray gneiss, from an ornamental stone extraction region in Santo Antônio de Padua, which is a Brazilian city that is located in the Northwest of the Rio de Janeiro state (Fig. 1).