Analysis of the condition of conservation and the forms of alteration in the stone monuments in São Paulo City

Abstract

There are countless monuments and buildings made of stone material in the São Paulo City mainly in the downtown area, which was a small village until the beginning of the 20 th century. It was only after the progress resulting from sugar and coffee that São Paulo became a modern city. The rocks used were mainly granites and some sedimentary and metamorphic rocks, displaying a wide variety of stones. Due to the fact that the monuments are placed outdoors, they are mostly affected by weathering, with the additional contribution of microorganisms and pollution. Several forms of alteration are identified, such as: deposit, encrustation, discolouration, spot, alveolization, biological colonization, efflorescence, concretion, exfoliation, missing part, chipping, soiling, fracture and hairline crack. Besides the weathering, there is another kind of deterioration, vandalism, in the form of graffiti, which promotes severe damage to them. For the characterization of the alteration present in the stone monuments, in addition to the traditional methods, the use of non-destructive methods, such as ultrasonic velocity determination, spectrophotometry, sclerometry and water absorption, is very helpful because they allow the data to be obtained directly on the monument without causing them any damage, thus preserving their integrity and esthetic. For this reason, these methods are the most suitable for studying heritage preservation.