Degradation of granitic rocks used as construction material in historic building of A Coruña (NW Spain)

Abstract

Granitic rocks are exposed to weathering processes determined by intrinsic and extrinsic factors. That weathering process increases the granite porosity and is the main forerunner of erosion. The research of weathering and decay of rocks used as construction material in buildings belonging to the Monumental Heritage also implies the consideration of factors related to each building and their environment, as well. In this work, decay of two types of granitic rocks (San Pedro leucogranite and Bregua granodiorite) used in the building of historic monuments from A Coruña (NW Spain) is studied. The field study of decay of ahslars of the buildings and the quarry surfaces, and the later research of the surface mechanical strength and porosity of both rock types suggest that the high decay of ashlars in monuments is related to the use of rock types weathered in the natural massifs. Also, there exist different factors related to the building of those monuments that increase the decay process.