Caracterização e comparação macro e microscópica, físico-mecânica e de alterabilidade de calcários ornamentais das Bacias Lusitaniana (Portugal) e Potiguar (RN – Brasil)

Abstract

Brazil and Portugal are among the ten largest producers of ornamental rock in the world. Filstone Beije limestones MF and Filstone Blue belong to the Member of Pedreira da Pedreira of the Lusitaniana Basin (Portugal), while the Paraná Crema belongs to the Jandaíra Formation of the Potiguar Basin (Rio Grande do Norte). This research aims at characterizing and comparing the macro and microscopic characteristics, physico-mechanical, surface friction, porous medium and alterability of the three above-mentioned carbonate rocks in order to evaluate its better application. For this purpose, the following tests were performed: determination of physical indices, resistance to uniaxial compression, modulus of rupture, flexion at four points and freezing and thawing, ultrasonic wave propagation velocity, hard body impact and coefficient of expansion under the ABNT, ASTM and experimental methods of the author; wear of amsler, knoop microhardness, slip and roughness, under ABNT, CEN and experimental methods of the author; porosity and gas permeability, porosity by mercury intrusion, computed tomography, ultrasonic wave velocity and scanning electron microscopy, following the own laboratory methodologies and the ISO standard; chemical resistance, staining resistance, Soxhlet extractor, salt fog and salt crystallization, following the ABNT, CEN norms and experimental methods of the author. Macro and microscopic analyzes of three limestones were carried out to compare with the results of the tests, in particular: composition, quantity and grain size, compaction and porosity. These analyzes are in agreement with the tests performed and the results of these tests, in general, satisfy the expected values. It is concluded that Paraná Cream can be applied as a structural and coating element (interior and / or exterior), while Filstone Beije MF and Filstone Blue limescale should be waterproofed and / or resins, mainly in wet and ice. The three limestones can be applied as a coating to floors that are subject to falling objects, and the plates of the Parana Cream should have a thickness greater than conventional (3 cm), and subject to heavy traffic, avoiding humid places and with high rates rainfall. The three carbonate varieties can be applied in environments with large thermal amplitudes, but Filstone limestones should only be applied in dry and / or indoor environments and without the formation of ice, especially Filstone Blue. In general, the Parana Cream is the less porous limestone and less likely to be deformed, contrary to Filstone Beije MF. Filstone Beije MF and Filstone Blue limestones have the greatest changes in color and brightness because they are the most porous and of the largest granulations. Application of Filstone Blue limestone should be avoided in saline environments or with strong acids (HCl, HNO3 and sodium sulfate), as well as Filstone Beije MF limestone in humid environments or with strong acid H2SO4. Waterproofing should be used to avoid reactions causing color change, loss of brightness and mass, generating pathologies and loss of aesthetic function.