Revista Egitania Sciencia - Volume 9 | ARTICLE


Author: Ana Antão (

Publication: Revista Egitania Sciencia - Volume 9

Rock weathering brings deep changes in their physical, chemical, mineralogical and textural properties which will be reproduced in their mechanical behavior. In order to assess this influence on the Guarda granite that appears in central Portugal with different weathering grades, several index tests, and capillarity and permeability tests were done. The samples were obtained in the field by coring, and prepared in the laboratory, the cylindrical samples having a height to diameter ratio around 2. Big samples were used in all tests in all grades of weathering, due to the coarse fabric of the rock. Correlations were established for this granite, between is uniaxial compression and point load resistance and some physical properties (porosity, dry density and ultrasonic velocity), and related whit the alteration presented by the rock samples. Those tests have confirmed that the grain size, the texture, namely the pores and fissures, and the weathering are responsible for the variation of the strength and deformation properties of the granite. We have found that the increase of porosity above 2% is marked by a significant reduction of the mechanical properties of the granite. Good correlations were established between porosity, dry density, ultrasonic velocity, capillarity, weathering grades and the uniaxial and point load tests, and some equations were proposed between those properties. It is also proposed a correlation coefficient between point load strength and uniaxial compressive strength specific for each weathering grade presented by the rock.

Keywords: Granite, weathering, mechanical behavior, index tests

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