Petrophysical characterization of both original and replacement stone used in architectural heritage of Morelia (Mexico)

Abstract

One of the requirements for the construction of new buildings and restoration of historic ones in the centre of the Morelia city (Michoacán state, México) should be the aesthetical homogeneity of the used materials. Color of new rocks must be similar to the pink original stone used. Currently, three rock varieties have been employed for building restoration: Cointzio, Jamaica and Tlalpujahua stones. These rocks have been used during the last decades, but the selection criterion was exclusively limited to their similar color to the original rock and no petrophysical criterion was taken into account. A complete petrographic and petrophysical characterization of each rock was carried out in this paper. This study was focused on porosity, hydric and durability tests (capillarity, water absorption, water desorption, and salt crystallization test). According to the results, the original rock (Piedra Vieja variety) presents the best characteristics to be used as building material due to its relative low porosity (around 26%), its medium capillary coefficient and its low water absorption and desorption coefficients. The Jamaica Stone is revealed as the most suitable replacement rock in the Morelia’s Heritage due to its similar petrophysical behaviour. Finally, the use of the Cointzio Stone is not recommended in outdoor areas due to its low durability and its water absorption facility.