Considerations on Granite Dimension Stone Porosity and Modifications from Quarry to Slabs: Fid-Bau Portal

Considerations on Granite Dimension Stone Porosity and Modifications from Quarry to Slabs

Frasca, Maria H.B.O.

This paper presents the physical and petrographic characterization of selected granitic rock types from several quarries in Brazil and aims to contribute to a better knowledge of the engineering properties of granite dimension stone, focusing on laboratory physical determinations and the possible changes that would occur along processing operations, i. e., from the quarried rock to the polished slabs or tiles. The tests – petrography and porosity determinations – led to the collection of parameters of in natura and processed rock material, respectively from specimens obtained from small cubic blocks and polished slabs, situations considered representative of the stresses to which the rock is submitted to during the several processing stages. The results indicated that porosity tends to be higher for “tiles” than for “blocks”, and that “S-type granites” have higher porosity/open-pores values than “ordinary granites”, mainly due to their conspicuous microcracking. Moreover, in spite porous configuration may be modified during stone processing, it was found that such changes are not homogeneous and intrinsically associated to the petrographic characteristics, as previous microcracking and alteration states. Finally, as the new physical conditions, acquired after processing, may influence the stone durability, it is strongly suggested that they should be taken into account, as an additional criterion, to the cladding or flooring natural stone selection and specification.