Rock Alteration and its Relation to Surface Finishing

Abstract

Rock finishing is a valuable tool used by architects to improve contrasts in decoration pattern in walls or building façades as they exhibit textures and color differences on their surfaces according to the type of finishing. When exposed to aggressive environment, these finishing impose different rate of alteration in the rocks as their ability to absorb humidity is also different for each type of finishing. Special types of silicate rocks underwent experiments in order to test their response to salt fog atmosphere. The study was centered on surface aspects of polished and honed finishing and their mass loss during seven salt fog cycles. All rocks studied are identified in the rock industry as granites although some are differently classified according to their petrography. They are: Blue Bahia, Belfast, Amazonite, Baltic Brown, Imperial Brown and Blue Labrador “Granites”. Each one has a particular feature to justify its inclusion in the study, as texture, mineral composition or specific occurrence and mineral association.